Pig bedding biochar(PBBC)and Cd-enriched Perilla frutescenswere used for joint remediation of Cd-contaminated soil.Cd-contaminated soil was treated with different concentration of PBBC.The physiological and biochemica...Pig bedding biochar(PBBC)and Cd-enriched Perilla frutescenswere used for joint remediation of Cd-contaminated soil.Cd-contaminated soil was treated with different concentration of PBBC.The physiological and biochemical indicators of P.frutescens was evaluated under different Cd stress,including biomass,antioxidant system.Meanwhile Cd bioavailability,enzyme activity and nutrient bioavailability of the soil were monitored.Results revealed that PBBC at 1%and 5%levels led to decreased diethylenetriaminepentaacetic acid-extractable Cd(DTPA-Cd)content in soil by 19.09%-20.05%and 30.10%-47.08%,respectively.Moreover,PBBC promoted the transformation of exchangeable Cd(EXC-Cd)into a more stable form,enhanced soil enzymes(peroxidase,acid phosphatase,urease,and sucrase)activities,and alleviated P.frutescens's oxidative stress.PBBC increased its biomass,consequently enhancing Cd accumulation in the plant's,thereby improving Phytoextraction rate(PER).1%PBBC showed the best effect,with a total biomass increased 21.42%-26.94%,PERwas enhanced by 39.83%-54.82%.This study justifies that the combining PBBC with P.frutescens enhances Cd removal fromsoil,making the PBBC-P.frutescens a promising choice for treating Cd-polluted soil.展开更多
Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of...Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of bedding slopes,each with different weak interlayers:one with a homogeneous weak layer and another with discontinuous interfaces.Shaking table tests were conducted to compare their seismic performance.The results show that the peak ground acceleration(PGA)values above the weak interlayer in model A were significantly higher than those in model B,with the differences increasing as the input wave amplitude increased.The peak earth pressure(PEP)values at the tensile failure boundary at the rear edge of model A were also higher,whereas those within the weak layer at the toe of model A were lower than those in model B.Deformation analysis revealed that the maximum principal strain in model A initially appeared at the upper part of the tensile failure boundary,while the maximum shear strain was concentrated near the rear edge within the weak layer.In contrast,model B exhibited the opposite strain distribution.These findings provide insight into the impact of weak interlayers on the dynamic response and deformation of bedding slopes,highlighting the importance of considering this factor in seismic landslide investigations and failure mode predictions.展开更多
Shale reservoirs have abundant bedding structures,which deeply alter the mechanical properties of rocks,and thus affect the reservoir stimulation performance.Previous research mostly focuses on the effects of parallel...Shale reservoirs have abundant bedding structures,which deeply alter the mechanical properties of rocks,and thus affect the reservoir stimulation performance.Previous research mostly focuses on the effects of parallel bedding on fracture propagation,while the mechanical properties and mechanisms of fracture propagation remain unclear for rocks with complex wavy bedding(e.g.China’s continentalorigin Gulong shale).Herein,a mixed phase-field fracture model of the wavy-bedding shale was applied,based on the local tension-compression decomposition phase field method(PFM)and geometric structure generation algorithm for the bedding with controllable morphological features.The parametric analysis of fracture propagation behaviors in the case of abundant complex bedding structures showed that with wavy bedding,the vertical fracture propagation rate is far higher than the horizontal propagation rate.Moreover,the development of branch fractures is suppressed during the fracturing process of the wavy-bedding sample,and the stimulated volume is limited,which is different from the characteristic of parallel bedding that promotes horizontal fracture initiation and propagation.The results showed that larger amplitudes,higher frequencies,higher inclination angles,and larger strengths of wavy bedding all promote the formation of vertical penetrating fractures and suppress the growth of branch fractures.Under such circumstances,it is hard to create a well-connected fracture network after fracturing.This research may provide a theoretical basis for understanding fracture behaviors in rocks with such complex wavy bedding.展开更多
The increasing demand for mineral resources has significantly deepened the excavation depths of open-pit mines.Large-scale deformation disasters caused by landslides on open pit mine slopes occur frequently,posing sev...The increasing demand for mineral resources has significantly deepened the excavation depths of open-pit mines.Large-scale deformation disasters caused by landslides on open pit mine slopes occur frequently,posing severe threats to human safety and mine operations.Therefore,research on monitoring and early warning technologies for openpit mine landslides is of utmost importance.The emergence of the Newtonian force monitoring and early warning system has introduced an effective new approach for landslide monitoring in open-pit mines and has been successfully applied in the Nanfen openpit mine,where it monitored landslides and issued early warnings up to 16 hours in advance.This study focuses on the bedding rock slope on the footwall of the Nanfen open pit mine,analyzing the geological conditions of the mining area.Through laboratory experiments,the mechanical parameters and mineral composition characteristics of the regional rock mass(greenschist)are obtained.A geological mechanical model of the landslide was then constructed,and the NPR anchor cable numerical analysis model was developed using FLAC3D numerical simulation software to analyze the variation patterns of Newtonian force during landslides.Based on this analysis,the influence of different NPR anchor cable parameters(including anchor cable inclination angle,spacing,and pre-tension force)on the Newtonian force was investigated.Comparative results indicate that the optimal design parameters for the NPR anchor cables are a 25°inclination angle,40 m anchoring spacing,and a 400 kN pre-tension force.Additionally,it was found that the sensitivity of these three key parameters to the Newtonian force load,from highest to lowest,is as follows:pre-tension force,spacing,and inclination angle.This optimal configuration provides practical guidance for the design of NPR anchor cables in Newtonian force monitoring applications,offering theoretical and technical support for future landslide monitoring and early warning.展开更多
Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects...Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects as static loads often underestimates rock slope stability.The development of a practical stability analysis approach for ABRSs,particularly in slope engineering design,is imperative.This study proposes a stability evaluation model for ABRSs,incorporating the viscoelastic properties of rock,to quantitatively assess the safety factor and failure surface under seismic conditions.The mathematical description of the pseudo-dynamic method,derived in this study,accounts for the viscoelastic properties of ABRSs and integrates the HoekeBrown failure criterion with the Kelvin-Voigt stress-strain relationship of rocks.Furthermore,to address concurrent translation-rotation failure in ABRSs,upper bound limit analysis is utilized to quantify the safety factor.Through a comparison with existing literature,the proposed method considers the effect of harmonic vibration on the stability of ABRSs.The obtained safety factor is lower than that of the quasi-static method,with the resulting percentage change exceeding 5%.The critical failure surface demonstrates superior positional accuracy compared to the Aydan and Adhikary basal planes,with minimal error observed between the physical model test and the numerical simulation test.The parameter sensitivity analysis reveals that the inclination of ABRSs exhibits the highest sensitivity(Sk)value across the three levels of horizontal seismic coefficient(kh).The study aims to devise an expeditious calculation approach for assessing the stability of ABRSs during seismic events,intending to offer theoretical guidance for their stability analysis.展开更多
In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefo...In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.展开更多
The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were ca...The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.展开更多
The fracture network of hydraulic crack is significantly influenced by the bedding plane in coalbed methane extraction.Under mode Ⅱ loading,crack deflection holds a key position in hydraulic cracking,especially in hy...The fracture network of hydraulic crack is significantly influenced by the bedding plane in coalbed methane extraction.Under mode Ⅱ loading,crack deflection holds a key position in hydraulic cracking,especially in hydraulic shearing.This study first analyzed the crack deflection theory of layered rock.The semi-circle bending test under asymmetric loading is performed,and the four-dimensional Lattice Spring Model(4D-LSM)is established to examine how the bedding parameters affect coal crack propagation under mode Ⅱ dominant loads.The 4D-LSM results are comparable to the coal loading test results under quasi-mode Ⅱ and the analytical prediction of crack deflection theory.During mode Ⅱ loading,the coal crack propagation is greatly influenced by the angle,strength,and elastic modulus of the bedding plane,while the effects of thickness and spacing of bedding are insignificant.The crack of coal tends to propagate towards the bedding,following a decrease in bedding angle,a decrease in bedding strength,and an increase in elastic modulus.With higher bedding strength,spacing,and thickness,the peak load on the coal sample is higher.The influences of bedding strength,elastic modulus,spacing,and thickness on the peak load of coal samples and its anisotropy gradually decrease.It is proved that compared with the tangential stress ratio and traditional energy release ratio theories,the corrected energy release ratio criterion can more accurately predict the direction of crack deflection of coal,especially under mode Ⅱ loading.The results can provide assistance in the design of initiation pressure and fracturing direction in coal seam hydraulic fracturing.展开更多
Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in p...Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in plains due to multi-seam coal mining and the instability of natural bedding slopes, yet the cumulative impact of different mining sequences on bedding slopes has been less explored. This study combines drone surveys and geological data to construct a comprehensive three-dimensional model of bedding slopes. Utilizing FLAC3D and PFC2D models, derived from laboratory experiments, it simulates stress, deformation, and failure dynamics of slopes under various mining sequences. Incorporating fractal dimension analysis, the research evaluates the stability of slopes in relation to different mining sequences. The findings reveal that mining in an upslope direction minimizes disruption to overlying strata. Initiating extraction from lower segments increases tensile-shear stress in coal pillar overburdens, resulting in greater creep deformation towards the downslope than when starting from upper segments, potentially leading to localized landslides and widespread creep deformation in mined-out areas. The downslope upward mining sequence exhibits the least fractal dimensions, indicating minimal disturbance to both strata and surface. While all five mining scenarios maintain good slope stability under normal conditions, recalibrated stability assessments based on fractal dimensions suggest that downslope upward mining offers the highest stability under rainfall, contrasting with the lower stability and potential instability risks of upslope downward mining. These insights are pivotal for mining operations and geological hazard mitigation in multi-seam coal exploitation on bedding slopes.展开更多
Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying expl...Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying explosion loads remains unclear.In this study,prefabricated perforated shale samples with parallel and vertical bedding are fractured under five distinct explosion loads using a MISEF experimental setup.High-frequency explosion pressure-time curves were monitored within an equivalent perforation,and computed tomography scanning along with three-dimensional reconstruction techniques were used to investigate fracture propagation patterns.Additionally,the formation mechanism and influencing factors of explosion crack-generated fines(CGF)were clarified by analyzing the morphology and statistics of explosion debris particles.The results indicate that methane explosion generated oscillating-pulse loads within perforations.Explosion characteristic parameters increase with increasing initial pressure.Explosion load and bedding orientation significantly influence fracture propagation patterns.As initial pressure increases,the fracture mode transitions from bi-wing to 4–5 radial fractures.In parallel bedding shale,radial fractures noticeably deflect along the bedding surface.Vertical bedding facilitates the development of transverse fractures oriented parallel to the cross-section.Bifurcation-merging of explosioninduced fractures generated CGF.CGF mass and fractal dimension increase,while average particle size decreases with increasing explosion load.This study provides valuable insights into MISEF technology.展开更多
Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining wal...Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.展开更多
Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This...Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This phenomenon has become a focal point in landslide research.Yet,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding slopes.This study investigated the Shanyang landslide in Shaanxi Province,China.Using field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such slopes.The findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of gravity.The landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip angle.The slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more pronounced.Notably,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the landslide.This study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure mechanism.These insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.展开更多
Shale reservoirs contain numerous bedding fractures,making the formation of complex fracture networks during fracturing a persistent technical challenge in evaluating shale fracture morphology.Distributed optical fibe...Shale reservoirs contain numerous bedding fractures,making the formation of complex fracture networks during fracturing a persistent technical challenge in evaluating shale fracture morphology.Distributed optical fiber sensing technology can effectively capture the process of fracture initiation and propagation,yet the evaluation method for the initiation and propagation of bedding fractures remains immature.This study integrates a distributed optical fiber sensing device based on optical frequency domain reflectometry(OFDR)with a large-scale true tri-axial fracturing physical simulation apparatus to conduct real-time monitoring experiments on shale samples from the Lianggaoshan Formation in the Sichuan Basin,where bedding is well-developed.The experimental results demonstrate that two bedding fractures in the shale sample initiated and propagated.The evolution characteristics of fiber-optic strain in a horizontal adjacent well,induced by the initiation and propagation of bedding fractures,are characterized by the appearance of a tensile strain convergence zone in the middle of the optical fiber,flanked by two compressive strain convergence zones.The initiation and propagation of the distal bedding fracture causes the fiber-optic strain in the horizontal adjacent well to superimpose,with the asymmetric propagation of the bedding fracture leading to an asymmetric tensile strain convergence zone in the optical fiber.Utilizing a finite element method coupled with a cohesive element approach,a forward model of fiber-optic strain in the horizontal adjacent well induced by the initiation and propagation of hydraulic fracturing bedding fractures was constructed.Numerical simulation analyses were conducted to evaluate the evolution of fiber-optic strain in the horizontal adjacent well,confirming the correctness of the observed evolution characteristics.The presence of a"wedge-shaped"tensile strain convergence zone in the fiber-optic strain waterfall plot,accompanied by two compressive strain convergence zones,indicates the initiation and propagation of bedding fractures during the fracturing process.These findings provide valuable insights for interpreting distributed fiber-optic data in shale fracturing field applications.展开更多
The perforating phase leads to complex and diverse hydraulic fracture propagation behaviors in laminated shale formations. In this paper, a 2D high-speed imaging scheme which can capture the interaction between perfor...The perforating phase leads to complex and diverse hydraulic fracture propagation behaviors in laminated shale formations. In this paper, a 2D high-speed imaging scheme which can capture the interaction between perforating phase and natural shale bedding planes was proposed. The phase field method was used to simulate the same conditions as in the experiment for verification and hydraulic fracture propagation mechanism under the competition of perforating phase and bedding planes was discussed.The results indicate that the bedding planes appear to be no influence on fracture propagation while the perforating phase is perpendicular to the bedding planes, and the fracture propagates along the perforating phase without deflection. When the perforating phase algins with the bedding planes, the fracture initiation pressure reserves the lowest value, and no deflection occurs during fracture propagation. When the perforating phase is the angle 45°, 60°and 75°of bedding planes, the bedding planes begin to play a key role on the fracture deflection. The maximum deflection degree is reached at the perforating phase of75°. Numerical simulation provides evidence that the existence of shale bedding planes is not exactly equivalent to anisotropy for fracture propagation and the difference of mechanical properties between different shale layers is the fundamental reason for fracture deflection. The findings help to understand the intrinsic characteristics of shale and provide a theoretical basis for the optimization design of field perforation parameters.展开更多
A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests wer...A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.展开更多
The existence of high-density bedding planes is a typical characteristic of shale oil reservoirs.Understanding the behavior of hydraulic fracturing in high-density laminated rocks is significant for promoting shale oi...The existence of high-density bedding planes is a typical characteristic of shale oil reservoirs.Understanding the behavior of hydraulic fracturing in high-density laminated rocks is significant for promoting shale oil production.In this study,a hydraulic fracturing model considering tensile failure and frictional slip of the bedding planes is established within the framework of the unified pipe-interface element method(UP-IEM).The model developed for simulating the interaction between the hydraulic fracture and the bedding plane is validated by comparison with experimental results.The hydraulic fracturing patterns in sealed and unsealed bedding planes are compared.Additionally,the effects of differential stress,bedding plane permeability,spacing,and the friction coefficient of the bedding plane are investigated.The results showed that a single main fracture crossing the bedding planes is more likely to form in sealed bedding planes under high differential stress.The decrease in bedding plane permeability and the increase in the friction coefficient also promote the fracture propagating perpendicular to the bedding planes.Shale with high-density bedding planes has a poorer fracturing effect than that with low-density bedding planes,as the hydraulic fracture is prone to initiate and propagate along the bedding planes.Moreover,higher injection pressure is needed to maintain fracture propagation along the bedding.An increase in bedding density will lead to a smaller fracturing area.Fracturing fluid seepage into the bedding planes slows shale fracturing.It is recommended that increasing the injection flow rate,selecting alternative fracturing fluids,and employing multi-well/multi-cluster fracturing may be efficient methods to improve energy production in shale oil reservoirs.展开更多
To explore the effect of bedding and initial confining pressure on the energy evolution characteristics of shale during the unloading process,samples were drilled with different bedding angles,unloading tests were con...To explore the effect of bedding and initial confining pressure on the energy evolution characteristics of shale during the unloading process,samples were drilled with different bedding angles,unloading tests were conducted under different initial confining pressures,and the me-chanical and energy evolution characteristics of shale during the unloading process were analyzed.The results show that the stressestrain curve of the unloading test can be divided into the linear elasticity stage,the stable crack growth stage,the accelerated crack growth stage,and the post-failure stage.Critical confining pressure can show the relative strength of the rock samples.The elastic modulus and Poisson's ratio increase with an increase in axial preset load.The elastic modulus increases with the bedding angle,and the effect of the bedding angle on the Poisson's ratio is insignificant.The energy evolution of the unloading test can be divided into three stages:energy accumulation,energy dissipation,and energy release.The larger the axial preset load,the higher the critical confining pressure,the higher the elastic modulus,and the higher the Poisson's ratio.The total energy,elastic energy,and dissipation energy all increase with the increase in the initial confining pressure,and the correlation is high.Confining pressure enhances the ability of the shale sample to store elastic energy and improves the ability of the shale sample to resist internal crack propagation.The total energy,elastic energy,and dissipated energy of the samples in the failure point decrease first and then increase with the increase in the bedding angle.The maximum value can be obtained when the bedding angle is 0°.The elastic energy and dissipated energy of shale are highly heterogeneous due to bedding,and the effects of bedding should be taken into account when exploring the law of rock deformation and failure from an energy perspective.展开更多
This paper aims to explore innovative bedding designs within the artistic home concept by studying the paintings of Mark Rothko,focusing on the application of his color and form.Rothko’s Abstract Expressionism style ...This paper aims to explore innovative bedding designs within the artistic home concept by studying the paintings of Mark Rothko,focusing on the application of his color and form.Rothko’s Abstract Expressionism style and his unique approach to color usage provide a rich source of inspiration for modern bedding design.The study begins with an analysis of the historical background and developmental stages of Rothko’s painting style,clarifying the core values of his art and the formative characteristics and color usage across different periods.Subsequently,the paper proposes four bedding design schemes,themed around the four seasons-Spring,Summer,Autumn,and Winter.Each scheme attempts to translate the visual elements and emotional ambiance of a specific Rothko work into the color and pattern of bedding design.By utilizing modern design software,the color blocks,lines,and textures from the art are meticulously replicated and adjusted according to the color atmosphere and design needs of each season,ensuring each bedding set possesses a unique artistic aesthetic and practical value.This interdisciplinary application not only enhances the artistic atmosphere of home environments but also provides new perspectives and creative spaces for modern home design,showcasing the perfect integration of art and everyday life.This research is expected to bring fresh inspiration to the field of artistic home design,promote further integration of art and design,and provide more personalized and artistically valuable home options for consumers who appreciate Rothko’s works.展开更多
[Objective] The study was conducted to optimize the operation parameters of water control equipment for deep-litter beddings. [Method] A four-factor three-level orthogonal design was adopted to optimize experimental t...[Objective] The study was conducted to optimize the operation parameters of water control equipment for deep-litter beddings. [Method] A four-factor three-level orthogonal design was adopted to optimize experimental temperature, stopping time of aeration, aeration time and aeration rate by 9 groups of experiments, so as to improve the water removal efficiency of adopted mixed and reduce operation energy consumption. [Result] The average water contents in the mixed bedding under 3 temperatures decreased by 4.58% ±2.91%, 13.17% ±3.77% and 10.8% ±7.72%, respectively; the highest water removal efficiency could be achieved under an experimental temperature at 45 ℃, stopping time of aeration of 15 min, aeration time of 7 min, and an aeration rate at 4 m^3/min, which formed the optimal factor combination mode of the operation parameter of the water control equipment; the effects of various experimental factors on water content in the bedding were in order of aeration ratetemperatureaeration timestopping time of aeration; and the effects of various experimental factors on water removal efficiency in the bedding were in order of temperatureaeration rateaeration timestopping time of aeration. [Conclusion] After the optimization of operation parameters of the water control equipment for the deep-litter bedding, water removal efficiency of the mixed bedding could be improved, and the operation energy consumption of the equipment could be reduced.展开更多
The selection and compatibility of the microbial strains and bedding materials in a deep-litter system is the primary issues for this ecological breeding technology. In this paper, we analyzed and summarized the categ...The selection and compatibility of the microbial strains and bedding materials in a deep-litter system is the primary issues for this ecological breeding technology. In this paper, we analyzed and summarized the categories of microbial strains and bedding materials suitable for a deep-litter system, the fermentation properties of different microbes, the parameter requirements of bedding materials, and the fermentation process led by functional microbial flora in a deep-litter system, with the objective to provide theoretical bases and practical guidance for the promotion of deep-litter breeding method nationwide.展开更多
基金supported by the Science and Technology Innovation of Fujian Agriculture and Forestry University(Nos.KFB23079 and KFB23065).
文摘Pig bedding biochar(PBBC)and Cd-enriched Perilla frutescenswere used for joint remediation of Cd-contaminated soil.Cd-contaminated soil was treated with different concentration of PBBC.The physiological and biochemical indicators of P.frutescens was evaluated under different Cd stress,including biomass,antioxidant system.Meanwhile Cd bioavailability,enzyme activity and nutrient bioavailability of the soil were monitored.Results revealed that PBBC at 1%and 5%levels led to decreased diethylenetriaminepentaacetic acid-extractable Cd(DTPA-Cd)content in soil by 19.09%-20.05%and 30.10%-47.08%,respectively.Moreover,PBBC promoted the transformation of exchangeable Cd(EXC-Cd)into a more stable form,enhanced soil enzymes(peroxidase,acid phosphatase,urease,and sucrase)activities,and alleviated P.frutescens's oxidative stress.PBBC increased its biomass,consequently enhancing Cd accumulation in the plant's,thereby improving Phytoextraction rate(PER).1%PBBC showed the best effect,with a total biomass increased 21.42%-26.94%,PERwas enhanced by 39.83%-54.82%.This study justifies that the combining PBBC with P.frutescens enhances Cd removal fromsoil,making the PBBC-P.frutescens a promising choice for treating Cd-polluted soil.
基金funding support from the National Nature Science Foundation of China(Grant No.41931296)the Open Research Project of Sichuan Provincial Key Laboratory for Major Hazard Source Monitoring and Control(Grant No.KFKT2023-4)the 57#Project(Grant No.JH2024015).
文摘Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of bedding slopes,each with different weak interlayers:one with a homogeneous weak layer and another with discontinuous interfaces.Shaking table tests were conducted to compare their seismic performance.The results show that the peak ground acceleration(PGA)values above the weak interlayer in model A were significantly higher than those in model B,with the differences increasing as the input wave amplitude increased.The peak earth pressure(PEP)values at the tensile failure boundary at the rear edge of model A were also higher,whereas those within the weak layer at the toe of model A were lower than those in model B.Deformation analysis revealed that the maximum principal strain in model A initially appeared at the upper part of the tensile failure boundary,while the maximum shear strain was concentrated near the rear edge within the weak layer.In contrast,model B exhibited the opposite strain distribution.These findings provide insight into the impact of weak interlayers on the dynamic response and deformation of bedding slopes,highlighting the importance of considering this factor in seismic landslide investigations and failure mode predictions.
基金supported by the Technology Project of CNPC(Grant No.2023ZZ08)the National Natural Science Foundation of China(Grant No.52274058)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2090002025).
文摘Shale reservoirs have abundant bedding structures,which deeply alter the mechanical properties of rocks,and thus affect the reservoir stimulation performance.Previous research mostly focuses on the effects of parallel bedding on fracture propagation,while the mechanical properties and mechanisms of fracture propagation remain unclear for rocks with complex wavy bedding(e.g.China’s continentalorigin Gulong shale).Herein,a mixed phase-field fracture model of the wavy-bedding shale was applied,based on the local tension-compression decomposition phase field method(PFM)and geometric structure generation algorithm for the bedding with controllable morphological features.The parametric analysis of fracture propagation behaviors in the case of abundant complex bedding structures showed that with wavy bedding,the vertical fracture propagation rate is far higher than the horizontal propagation rate.Moreover,the development of branch fractures is suppressed during the fracturing process of the wavy-bedding sample,and the stimulated volume is limited,which is different from the characteristic of parallel bedding that promotes horizontal fracture initiation and propagation.The results showed that larger amplitudes,higher frequencies,higher inclination angles,and larger strengths of wavy bedding all promote the formation of vertical penetrating fractures and suppress the growth of branch fractures.Under such circumstances,it is hard to create a well-connected fracture network after fracturing.This research may provide a theoretical basis for understanding fracture behaviors in rocks with such complex wavy bedding.
基金supported by collaborative innovation center for prevention and control of mountain geological hazards of Zhejiang province(Project number:PCMGH-2022-06)。
文摘The increasing demand for mineral resources has significantly deepened the excavation depths of open-pit mines.Large-scale deformation disasters caused by landslides on open pit mine slopes occur frequently,posing severe threats to human safety and mine operations.Therefore,research on monitoring and early warning technologies for openpit mine landslides is of utmost importance.The emergence of the Newtonian force monitoring and early warning system has introduced an effective new approach for landslide monitoring in open-pit mines and has been successfully applied in the Nanfen openpit mine,where it monitored landslides and issued early warnings up to 16 hours in advance.This study focuses on the bedding rock slope on the footwall of the Nanfen open pit mine,analyzing the geological conditions of the mining area.Through laboratory experiments,the mechanical parameters and mineral composition characteristics of the regional rock mass(greenschist)are obtained.A geological mechanical model of the landslide was then constructed,and the NPR anchor cable numerical analysis model was developed using FLAC3D numerical simulation software to analyze the variation patterns of Newtonian force during landslides.Based on this analysis,the influence of different NPR anchor cable parameters(including anchor cable inclination angle,spacing,and pre-tension force)on the Newtonian force was investigated.Comparative results indicate that the optimal design parameters for the NPR anchor cables are a 25°inclination angle,40 m anchoring spacing,and a 400 kN pre-tension force.Additionally,it was found that the sensitivity of these three key parameters to the Newtonian force load,from highest to lowest,is as follows:pre-tension force,spacing,and inclination angle.This optimal configuration provides practical guidance for the design of NPR anchor cables in Newtonian force monitoring applications,offering theoretical and technical support for future landslide monitoring and early warning.
基金funding support from the National Natural Science Foundation of China(Grant No.42072303)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(Grant No.SKLGP2021Z004).
文摘Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects as static loads often underestimates rock slope stability.The development of a practical stability analysis approach for ABRSs,particularly in slope engineering design,is imperative.This study proposes a stability evaluation model for ABRSs,incorporating the viscoelastic properties of rock,to quantitatively assess the safety factor and failure surface under seismic conditions.The mathematical description of the pseudo-dynamic method,derived in this study,accounts for the viscoelastic properties of ABRSs and integrates the HoekeBrown failure criterion with the Kelvin-Voigt stress-strain relationship of rocks.Furthermore,to address concurrent translation-rotation failure in ABRSs,upper bound limit analysis is utilized to quantify the safety factor.Through a comparison with existing literature,the proposed method considers the effect of harmonic vibration on the stability of ABRSs.The obtained safety factor is lower than that of the quasi-static method,with the resulting percentage change exceeding 5%.The critical failure surface demonstrates superior positional accuracy compared to the Aydan and Adhikary basal planes,with minimal error observed between the physical model test and the numerical simulation test.The parameter sensitivity analysis reveals that the inclination of ABRSs exhibits the highest sensitivity(Sk)value across the three levels of horizontal seismic coefficient(kh).The study aims to devise an expeditious calculation approach for assessing the stability of ABRSs during seismic events,intending to offer theoretical guidance for their stability analysis.
基金Projects(52208369,52309138,52108320)supported by the National Natural Science Foundation of ChinaProjects(2023NSFSC0284,2025ZNSFSC0409)supported by the Sichuan Science and Technology Program,ChinaProject(U22468214)supported by the Joint Fund Project for Railway Basic Research by the National Natural Science Foundation of China and China State Railway Group Co.,Ltd.
文摘In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.
基金supported by the National Natural Science Foundation of China (Grant No.52109125)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK20231217)the Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Chinese Academy of Sciences (Grant No.SKLGME023001).
文摘The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52225402,U1910206)the National Key Research and Development Project of China(Grant No.2022YFC3004602).
文摘The fracture network of hydraulic crack is significantly influenced by the bedding plane in coalbed methane extraction.Under mode Ⅱ loading,crack deflection holds a key position in hydraulic cracking,especially in hydraulic shearing.This study first analyzed the crack deflection theory of layered rock.The semi-circle bending test under asymmetric loading is performed,and the four-dimensional Lattice Spring Model(4D-LSM)is established to examine how the bedding parameters affect coal crack propagation under mode Ⅱ dominant loads.The 4D-LSM results are comparable to the coal loading test results under quasi-mode Ⅱ and the analytical prediction of crack deflection theory.During mode Ⅱ loading,the coal crack propagation is greatly influenced by the angle,strength,and elastic modulus of the bedding plane,while the effects of thickness and spacing of bedding are insignificant.The crack of coal tends to propagate towards the bedding,following a decrease in bedding angle,a decrease in bedding strength,and an increase in elastic modulus.With higher bedding strength,spacing,and thickness,the peak load on the coal sample is higher.The influences of bedding strength,elastic modulus,spacing,and thickness on the peak load of coal samples and its anisotropy gradually decrease.It is proved that compared with the tangential stress ratio and traditional energy release ratio theories,the corrected energy release ratio criterion can more accurately predict the direction of crack deflection of coal,especially under mode Ⅱ loading.The results can provide assistance in the design of initiation pressure and fracturing direction in coal seam hydraulic fracturing.
基金funded by the Sichuan Science and Technology Program (grant number 2022NSFSC1176)the open Fund for National Key Laboratory of Geological Disaster Prevention and Environmental Protection (grant number SKLGP2022K027)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (SKLGP2022Z001)。
文摘Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in plains due to multi-seam coal mining and the instability of natural bedding slopes, yet the cumulative impact of different mining sequences on bedding slopes has been less explored. This study combines drone surveys and geological data to construct a comprehensive three-dimensional model of bedding slopes. Utilizing FLAC3D and PFC2D models, derived from laboratory experiments, it simulates stress, deformation, and failure dynamics of slopes under various mining sequences. Incorporating fractal dimension analysis, the research evaluates the stability of slopes in relation to different mining sequences. The findings reveal that mining in an upslope direction minimizes disruption to overlying strata. Initiating extraction from lower segments increases tensile-shear stress in coal pillar overburdens, resulting in greater creep deformation towards the downslope than when starting from upper segments, potentially leading to localized landslides and widespread creep deformation in mined-out areas. The downslope upward mining sequence exhibits the least fractal dimensions, indicating minimal disturbance to both strata and surface. While all five mining scenarios maintain good slope stability under normal conditions, recalibrated stability assessments based on fractal dimensions suggest that downslope upward mining offers the highest stability under rainfall, contrasting with the lower stability and potential instability risks of upslope downward mining. These insights are pivotal for mining operations and geological hazard mitigation in multi-seam coal exploitation on bedding slopes.
基金funded by the National Key Research and Development Program of China(No.2020YFA0711800)the National Science Fund for Distinguished Young Scholars(No.51925404)+2 种基金the National Natural Science Foundation of China(No.12372373)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_2909)the Graduate Innovation Program of China University of Mining and Technology(No.2024WLKXJ134)。
文摘Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying explosion loads remains unclear.In this study,prefabricated perforated shale samples with parallel and vertical bedding are fractured under five distinct explosion loads using a MISEF experimental setup.High-frequency explosion pressure-time curves were monitored within an equivalent perforation,and computed tomography scanning along with three-dimensional reconstruction techniques were used to investigate fracture propagation patterns.Additionally,the formation mechanism and influencing factors of explosion crack-generated fines(CGF)were clarified by analyzing the morphology and statistics of explosion debris particles.The results indicate that methane explosion generated oscillating-pulse loads within perforations.Explosion characteristic parameters increase with increasing initial pressure.Explosion load and bedding orientation significantly influence fracture propagation patterns.As initial pressure increases,the fracture mode transitions from bi-wing to 4–5 radial fractures.In parallel bedding shale,radial fractures noticeably deflect along the bedding surface.Vertical bedding facilitates the development of transverse fractures oriented parallel to the cross-section.Bifurcation-merging of explosioninduced fractures generated CGF.CGF mass and fractal dimension increase,while average particle size decreases with increasing explosion load.This study provides valuable insights into MISEF technology.
基金supported by the Fujian Science Foundation for Outstanding Youth(Grant No.2023J06039)the National Natural Science Foundation of China(Grant No.41977259 and No.U2005205)Fujian Province natural resources science and technology innovation project(Grant No.KY-090000-04-2022-019)。
文摘Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.
基金jointly supported by the projects of the China Geological Survey(DD20230092,DD20201119)。
文摘Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This phenomenon has become a focal point in landslide research.Yet,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding slopes.This study investigated the Shanyang landslide in Shaanxi Province,China.Using field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such slopes.The findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of gravity.The landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip angle.The slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more pronounced.Notably,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the landslide.This study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure mechanism.These insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.
基金the financial support by National Natural Science Foundation of China(No.52334001)。
文摘Shale reservoirs contain numerous bedding fractures,making the formation of complex fracture networks during fracturing a persistent technical challenge in evaluating shale fracture morphology.Distributed optical fiber sensing technology can effectively capture the process of fracture initiation and propagation,yet the evaluation method for the initiation and propagation of bedding fractures remains immature.This study integrates a distributed optical fiber sensing device based on optical frequency domain reflectometry(OFDR)with a large-scale true tri-axial fracturing physical simulation apparatus to conduct real-time monitoring experiments on shale samples from the Lianggaoshan Formation in the Sichuan Basin,where bedding is well-developed.The experimental results demonstrate that two bedding fractures in the shale sample initiated and propagated.The evolution characteristics of fiber-optic strain in a horizontal adjacent well,induced by the initiation and propagation of bedding fractures,are characterized by the appearance of a tensile strain convergence zone in the middle of the optical fiber,flanked by two compressive strain convergence zones.The initiation and propagation of the distal bedding fracture causes the fiber-optic strain in the horizontal adjacent well to superimpose,with the asymmetric propagation of the bedding fracture leading to an asymmetric tensile strain convergence zone in the optical fiber.Utilizing a finite element method coupled with a cohesive element approach,a forward model of fiber-optic strain in the horizontal adjacent well induced by the initiation and propagation of hydraulic fracturing bedding fractures was constructed.Numerical simulation analyses were conducted to evaluate the evolution of fiber-optic strain in the horizontal adjacent well,confirming the correctness of the observed evolution characteristics.The presence of a"wedge-shaped"tensile strain convergence zone in the fiber-optic strain waterfall plot,accompanied by two compressive strain convergence zones,indicates the initiation and propagation of bedding fractures during the fracturing process.These findings provide valuable insights for interpreting distributed fiber-optic data in shale fracturing field applications.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52074315&U19B6003)。
文摘The perforating phase leads to complex and diverse hydraulic fracture propagation behaviors in laminated shale formations. In this paper, a 2D high-speed imaging scheme which can capture the interaction between perforating phase and natural shale bedding planes was proposed. The phase field method was used to simulate the same conditions as in the experiment for verification and hydraulic fracture propagation mechanism under the competition of perforating phase and bedding planes was discussed.The results indicate that the bedding planes appear to be no influence on fracture propagation while the perforating phase is perpendicular to the bedding planes, and the fracture propagates along the perforating phase without deflection. When the perforating phase algins with the bedding planes, the fracture initiation pressure reserves the lowest value, and no deflection occurs during fracture propagation. When the perforating phase is the angle 45°, 60°and 75°of bedding planes, the bedding planes begin to play a key role on the fracture deflection. The maximum deflection degree is reached at the perforating phase of75°. Numerical simulation provides evidence that the existence of shale bedding planes is not exactly equivalent to anisotropy for fracture propagation and the difference of mechanical properties between different shale layers is the fundamental reason for fracture deflection. The findings help to understand the intrinsic characteristics of shale and provide a theoretical basis for the optimization design of field perforation parameters.
基金supported by the National Natural Science Foundation of China (Grant No.52364004)the Basic Research Project of Guizhou University (Grant No.[2023]40)support by the Helmholtz Association’s Initiative and Networking Fund for the Helmholtz Young Investigator Group ARES (Contract No.VH-NG-1516).
文摘A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.
基金The authors wish to acknowledge the financial support from Key Laboratory of Deep Earth Science and Engineering(Sichuan University),Ministry of Education(DESE202202,H.Y)State Energy Center for Shale Oil Research and Development(33550000-22-ZC0613-0365,H.Y)+2 种基金National Natural Science Foundation of China(42307209,X.Y)China Postdoctoral Science Foundation(2022M712425,X.Y)Shanghai Pujiang Program(2022PJD076,X.Y).
文摘The existence of high-density bedding planes is a typical characteristic of shale oil reservoirs.Understanding the behavior of hydraulic fracturing in high-density laminated rocks is significant for promoting shale oil production.In this study,a hydraulic fracturing model considering tensile failure and frictional slip of the bedding planes is established within the framework of the unified pipe-interface element method(UP-IEM).The model developed for simulating the interaction between the hydraulic fracture and the bedding plane is validated by comparison with experimental results.The hydraulic fracturing patterns in sealed and unsealed bedding planes are compared.Additionally,the effects of differential stress,bedding plane permeability,spacing,and the friction coefficient of the bedding plane are investigated.The results showed that a single main fracture crossing the bedding planes is more likely to form in sealed bedding planes under high differential stress.The decrease in bedding plane permeability and the increase in the friction coefficient also promote the fracture propagating perpendicular to the bedding planes.Shale with high-density bedding planes has a poorer fracturing effect than that with low-density bedding planes,as the hydraulic fracture is prone to initiate and propagate along the bedding planes.Moreover,higher injection pressure is needed to maintain fracture propagation along the bedding.An increase in bedding density will lead to a smaller fracturing area.Fracturing fluid seepage into the bedding planes slows shale fracturing.It is recommended that increasing the injection flow rate,selecting alternative fracturing fluids,and employing multi-well/multi-cluster fracturing may be efficient methods to improve energy production in shale oil reservoirs.
基金supported by the Provincial Geological Exploration Projects in Guizhou Province(Grant Nos.52000024P0048BH10174 M)National Natural Science Foundation of China(Grant Nos.U1262209).
文摘To explore the effect of bedding and initial confining pressure on the energy evolution characteristics of shale during the unloading process,samples were drilled with different bedding angles,unloading tests were conducted under different initial confining pressures,and the me-chanical and energy evolution characteristics of shale during the unloading process were analyzed.The results show that the stressestrain curve of the unloading test can be divided into the linear elasticity stage,the stable crack growth stage,the accelerated crack growth stage,and the post-failure stage.Critical confining pressure can show the relative strength of the rock samples.The elastic modulus and Poisson's ratio increase with an increase in axial preset load.The elastic modulus increases with the bedding angle,and the effect of the bedding angle on the Poisson's ratio is insignificant.The energy evolution of the unloading test can be divided into three stages:energy accumulation,energy dissipation,and energy release.The larger the axial preset load,the higher the critical confining pressure,the higher the elastic modulus,and the higher the Poisson's ratio.The total energy,elastic energy,and dissipation energy all increase with the increase in the initial confining pressure,and the correlation is high.Confining pressure enhances the ability of the shale sample to store elastic energy and improves the ability of the shale sample to resist internal crack propagation.The total energy,elastic energy,and dissipated energy of the samples in the failure point decrease first and then increase with the increase in the bedding angle.The maximum value can be obtained when the bedding angle is 0°.The elastic energy and dissipated energy of shale are highly heterogeneous due to bedding,and the effects of bedding should be taken into account when exploring the law of rock deformation and failure from an energy perspective.
文摘This paper aims to explore innovative bedding designs within the artistic home concept by studying the paintings of Mark Rothko,focusing on the application of his color and form.Rothko’s Abstract Expressionism style and his unique approach to color usage provide a rich source of inspiration for modern bedding design.The study begins with an analysis of the historical background and developmental stages of Rothko’s painting style,clarifying the core values of his art and the formative characteristics and color usage across different periods.Subsequently,the paper proposes four bedding design schemes,themed around the four seasons-Spring,Summer,Autumn,and Winter.Each scheme attempts to translate the visual elements and emotional ambiance of a specific Rothko work into the color and pattern of bedding design.By utilizing modern design software,the color blocks,lines,and textures from the art are meticulously replicated and adjusted according to the color atmosphere and design needs of each season,ensuring each bedding set possesses a unique artistic aesthetic and practical value.This interdisciplinary application not only enhances the artistic atmosphere of home environments but also provides new perspectives and creative spaces for modern home design,showcasing the perfect integration of art and everyday life.This research is expected to bring fresh inspiration to the field of artistic home design,promote further integration of art and design,and provide more personalized and artistically valuable home options for consumers who appreciate Rothko’s works.
基金Supported by the Fund for Independent Innovation of Agricultural Sciences in Jiangsu Province(CX(13)3073)Jiangsu Science and Technology Support Program(BE2014-342-1)~~
文摘[Objective] The study was conducted to optimize the operation parameters of water control equipment for deep-litter beddings. [Method] A four-factor three-level orthogonal design was adopted to optimize experimental temperature, stopping time of aeration, aeration time and aeration rate by 9 groups of experiments, so as to improve the water removal efficiency of adopted mixed and reduce operation energy consumption. [Result] The average water contents in the mixed bedding under 3 temperatures decreased by 4.58% ±2.91%, 13.17% ±3.77% and 10.8% ±7.72%, respectively; the highest water removal efficiency could be achieved under an experimental temperature at 45 ℃, stopping time of aeration of 15 min, aeration time of 7 min, and an aeration rate at 4 m^3/min, which formed the optimal factor combination mode of the operation parameter of the water control equipment; the effects of various experimental factors on water content in the bedding were in order of aeration ratetemperatureaeration timestopping time of aeration; and the effects of various experimental factors on water removal efficiency in the bedding were in order of temperatureaeration rateaeration timestopping time of aeration. [Conclusion] After the optimization of operation parameters of the water control equipment for the deep-litter bedding, water removal efficiency of the mixed bedding could be improved, and the operation energy consumption of the equipment could be reduced.
基金Supported by the Special Fund for the Independent Innovation of Agricultural Sciences and Technology in Jiangsu Province[cx(12)1001-04]~~
文摘The selection and compatibility of the microbial strains and bedding materials in a deep-litter system is the primary issues for this ecological breeding technology. In this paper, we analyzed and summarized the categories of microbial strains and bedding materials suitable for a deep-litter system, the fermentation properties of different microbes, the parameter requirements of bedding materials, and the fermentation process led by functional microbial flora in a deep-litter system, with the objective to provide theoretical bases and practical guidance for the promotion of deep-litter breeding method nationwide.
