Geomechanical parameters are complex and uncertain.In order to take this complexity and uncertainty into account,a probabilistic back-analysis method combining the Bayesian probability with the least squares support v...Geomechanical parameters are complex and uncertain.In order to take this complexity and uncertainty into account,a probabilistic back-analysis method combining the Bayesian probability with the least squares support vector machine(LS-SVM) technique was proposed.The Bayesian probability was used to deal with the uncertainties in the geomechanical parameters,and an LS-SVM was utilized to establish the relationship between the displacement and the geomechanical parameters.The proposed approach was applied to the geomechanical parameter identification in a slope stability case study which was related to the permanent ship lock within the Three Gorges project in China.The results indicate that the proposed method presents the uncertainties in the geomechanical parameters reasonably well,and also improves the understanding that the monitored information is important in real projects.展开更多
Under the background of rapid economic development, the construction industry has entered a new stage of development, and the number of high-rise buildings is on the rise. However, due to the influence of geological c...Under the background of rapid economic development, the construction industry has entered a new stage of development, and the number of high-rise buildings is on the rise. However, due to the influence of geological conditions in the whole construction process of the project, the geotechnical slope construction faces many problems, especially the stability of the slope. If the slope construction quality cannot be guaranteed, the engineering construction of the whole project will be affected. In geotechnical engineering, slope reinforcement engineering has strong complexity and many influencing factors. It is necessary to select appropriate construction technology in combination with geological conditions in order to better ensure the construction quality. Compared with anti slide pile, anchor bolt support and other construction technologies, prestressed anchor cable construction technology has more significant advantages in construction quality, construction efficiency and greening, which is worthy of wide application.展开更多
This study aims to prepare ternary all-solid-waste cementitious materials to completely replace ordinary Portland cement(OPC).Ground granulated blast-furnace slag(GGBS),carbide slag(CS),sulfate solid waste phosphogyps...This study aims to prepare ternary all-solid-waste cementitious materials to completely replace ordinary Portland cement(OPC).Ground granulated blast-furnace slag(GGBS),carbide slag(CS),sulfate solid waste phosphogypsum(PG),electrolytic manganese residue(EMR)and desulfurized gypsum(DG)were used as raw materials to prepare GGBS-PG-CS(GPC),GGBS-EMR-CS(GEC)and GGBS-DG-CS(GDC)ternary all-solid-waste cementitious materials.Macro and microscopic tests were carried out to reveal the mechanical properties and microscopic characteristics,as well as to quantitatively evaluate the environmental and economic benefits.The results show that the optimal ratios of GPC,GEC and GDC are 80:18:2,60:36:4 and 80:18:2,respectively.The corresponding 28 d-unconfined compressive strength(UCS)are 1.62,1.22 and 1.01 times that of OPC,respectively.Carbon emissions and costs per unit strength can be reduced by more than 97%and 57%,respectively.Microscopic analysis shows that the incorporation of sulfate solid waste can synergistically activate GGBS with CS to induce the growth of more needle-like ettringite(AFt),which filled the internal pores and improved the strength of the cementitious material.The better mechanical properties of solidified engineering sediment waste(ESW)also confirm the feasibility of replacing OPC.In summary,this study developed all-solid-waste cementitious materials with excellent mechanical performance,low costs and carbon emissions,which provided a sustainable and economic solution for ESW stabilization.展开更多
An internet-based information and monitoring platform for the specific requirements of geotechnical engineering projects is presented. The platform is based on a hybrid-model approach consisting of a model-based infor...An internet-based information and monitoring platform for the specific requirements of geotechnical engineering projects is presented. The platform is based on a hybrid-model approach consisting of a model-based information management system and a resource management system, the latter also referred to as DCMS. Project key information can be accessed via the main user interface, the 'graphical navigator'. The graphical navigator provides also a direct access to additional information in the DCMS. Prompt reac-tion in exceptional situations as well as in daily work gets an extensive support. In practical applications it has been proven that this platform seems to be an adequate tool especially for risk assessment and management in geotechnical engineering projects. Components and advantages of the platform as well as ex periences from the applications are presented and discussed in the paper.展开更多
Landslides triggered by heavy rainfall pose a serious threat globally, endangering infrastructure and lives. Many previous landslide studies lack comprehensiveness and site specificity. Thus, a comprehensive investiga...Landslides triggered by heavy rainfall pose a serious threat globally, endangering infrastructure and lives. Many previous landslide studies lack comprehensiveness and site specificity. Thus, a comprehensive investigation is essential to understand the failure mechanisms and contributing factors for assessing potential future hazards. This study aims to investigate the debris flow landslide that occurred in Kavalappara, Kerala, India, on August 8, 2019, through an integrated approach combining geophysical test, weathering characterization, geotechnical, and numerical analyses. Shear wave velocity(V_s) was determined using the Multi-Channel Analysis of Surface Waves(MASW) test to obtain the substrata of the slope. Residual and unsaturated soil properties were obtained through ring shear and dew point potentiometer tests. The mineralogical composition of the soil was identified using Field-Emission Scanning Electron Microscopy(FE-SEM), Energy Dispersive XRay Analysis(EDAX), and X-Ray Diffraction(XRD) patterns. These investigation results focused on slope stability during rainfall infiltration using Limit Equilibrium(LEM) and Finite Element Analysis(FEM) for both low and high-intensity rainfall. Finally, the progressive failure mechanism of the landslide was analysed using the Finite Difference program(FDM). The soil profile showed a variation from loose to dense, with a V_(s) range of 172.85 m/s to 440.53 m/s. No rock layers were identified down to a depth of 15 m. The landslide area consists of migmatite as a parent rock, and the soil was identified as silty clay, comprising quartz and clay minerals. The FEM and LEM analyses reveal that the factor of safety was reduced to 0.83 due to increased pore water pressure and the degree of saturation. The pore water pressure ratio(r_(u)), estimated at 0.32, was used in the FDM. The landslide, initiated at r_u of 0.35, reached maximum velocities of 15.4 m/s horizontally and 12.4 m/s vertically. This study helps disaster management to analyse debris flow and find effective mitigation strategies for hilly areas.展开更多
Layered rock masses represent complex geological formations commonly encountered in the surrounding rock of deep engineering excavations(Hou et al.,2019;Xu et al.,2017;Yang C H et al.,2009;Xian and Tan,1989).These roc...Layered rock masses represent complex geological formations commonly encountered in the surrounding rock of deep engineering excavations(Hou et al.,2019;Xu et al.,2017;Yang C H et al.,2009;Xian and Tan,1989).These rock masses are predominantly composed of sedimentary,para-metamorphic,and volcanic rock types,characterized by a set of prominent,primary bedding structural planes(layers)exhibiting relatively consistent orientations and significant spatial continuity.展开更多
Acid mine drainage(AMD)leachate is a global pollutant issue that impacts groundwater environment quality.This study investigated the feasibility of a composite biopolymer-amended bentonite as a geosynthetic clay liner...Acid mine drainage(AMD)leachate is a global pollutant issue that impacts groundwater environment quality.This study investigated the feasibility of a composite biopolymer-amended bentonite as a geosynthetic clay liner core material to contain AMD leachate.The real AMD leachate with a pH of 3.1,sourced from an acidic pyrite tailings site,was employed as a specific test leachate used in this study.The composite biopolymer was composed of welan gum(WG)and xanthan gum(XG)at different dry weight-based ratios.Modified fluid loss(MFL)tests were conducted to evaluate hydraulic conductivity(k)of bentonites to optimize WG:XG ratio.Rheological properties of biopolymer solutions were measured,serving as indicative parameters of biopolymer elution.The results indicated biopolymer-amended bentonites with the WG:XG ratio of 8:2 possessed lowest k(1.5×10^(−11)m/s to 7.2×10^(−11)m/s),lower than unamended bentonite(1.2×10^(−10)m/s to 8.6×10^(−10)m/s)in the AMD leachate condition.In addition,biopolymer solutions with WG:XG ratio of 8:2 exhibited highest viscosity.Thermogravimetric analysis,ultraviolet–visible spectroscopy,and Fourier transform infrared spectroscopy were conducted on the composite biopolymer,revealing that WG and XG interacted via physical cross-linking.Additionally,scanning electron microscopy and atomic force microscopy images indicated that a physical cross-linking and dense network structure conformation was developed in the composite biopolymer hydrogel at the WG:XG ratio of 8:2.The results demonstrate that the composite biopolymer is a promising low-carbon amendment material for enhancing containment performance of bentonite used in geosynthetic clay liners to contain AMD leachate.展开更多
The dynamic evolution of fracture permeability presents a critical scientific challenge in rock masses.Understanding the mechanisms of rock mass permeability evolution is vital for engineering project design and opera...The dynamic evolution of fracture permeability presents a critical scientific challenge in rock masses.Understanding the mechanisms of rock mass permeability evolution is vital for engineering project design and operations.By integrating the discrete element method(DEM)with the finite element method(FEM),a numerical simulation framework for shear seepage in rough fractured shale has been developed to investigate the dynamic mechanisms of permeability evolution under varying confining pressures and during the shearing process.Numerical simulations were conducted on rough fractured samples under effective confining pressures ranging from 5 MPa to 20 MPa to monitor the aperture and permeability evolution of the fracture.The results of the numerical simulation are consistent with the experimental observations,indicating that both the shearing process and confining pressure significantly influence permeability.Moreover,the magnitude of the confining pressure is a crucial factor influencing the trend in permeability changes.Under a confining pressure of 5 MPa,fracture permeability initially increases significantly but decreases post-shearing.In contrast,a continuous decrease in fracture permeability is observed when the confining pressure exceeds 10 MPa.The results of the shear numerical simulation indicate that the confining pressure restricts fracture dilation during shearing,promotes the generation of rock debris,and decreases both the permeability and transmissivity of the fracture.The wear results obtained from numerical simulations are consistent with the experimental patterns and correlate with the joint roughness coefficient(JRC).This study proposed an effective numerical simulation method to reveal the evolution mechanism of fracture flow capacity,taking into account the wear of the fracture surface in shear simulations and the initial stress state of the rock in seepage simulations.This research explains the permeability evolution mechanism of fractured shale from a microscopic perspective,and the proposed numerical simulation method for shear seepage provides a powerful means to uncover the dynamic evolution mechanisms governing fracture permeability.展开更多
In recent years,microfluidic technology has emerged as a powerful and innovative tool,attracting significant attention for its ability to provide real-time visualization of CO_(2)flow,mass transfer,and reaction proces...In recent years,microfluidic technology has emerged as a powerful and innovative tool,attracting significant attention for its ability to provide real-time visualization of CO_(2)flow,mass transfer,and reaction processes in porous media.This review examines the application of microfluidic technology in CO_(2)sequestration in saline aquifers,emphasizing the advantages of saline aquifer for geological sequestration,including safety,high storage capacity,stability,and cost-effectiveness.The materials used for microfluidic chips and the design of microchannels are systematically reviewed,offering forward-looking recommendations for chip selection and microchannel characterization in future research on CO_(2)sequestration in saline aquifer.Based on a detailed analysis of advancements in microfluidic technology,this review highlights key findings related to CO_(2)trapping mechanisms,salt precipitation,and CO_(2)-water-rock chemical interactions within saline aquifers.Although microfluidic technology shows great promise in these areas,this review identifies limitations in current studies and outlines future research directions,aiming to promote further innovation and broader application of microfluidic technology in the field of CO_(2)sequestration in saline aquifer.展开更多
The rheological behavior of paste in mine backfilling systems is governed by multiple coupled mechanisms,including particulate structure evolution,time-dependent effects,spatially heterogeneous flow,and scale dependen...The rheological behavior of paste in mine backfilling systems is governed by multiple coupled mechanisms,including particulate structure evolution,time-dependent effects,spatially heterogeneous flow,and scale dependence.As a result,its macroscopic response cannot be adequately described by a single material parameter or purely local constitutive relations.Although significant progress has been made in experimental characterization and empirical modeling,rheological parameters reported under different conditions remain difficult to reconcile,highlighting the limitations of existing models in capturing structural evolution and nonlocal effects.This review provides a concise synthesis of current advances in paste rheology for mine backfilling applications,with emphasis on yield behavior,shear-rate-dependent nonlinear flow response,thixotropy,and shear history effects.The applicability and limitations of commonly used rheological models,including the Bingham and Herschel-Bulkley models,are critically examined.Key factors influencing paste rheology—such as particle gradation,temperature,and chemical additives—are discussed from a structure-controlled perspective.Finally,physics-constrained data-driven approaches are highlighted as a promising direction for improving the description and prediction of complex rheological behavior.Overall,this review emphasizes the need to balance experimental observability,model simplicity,and physical consistency,and highlights the importance of linking microstructural mechanisms,scale effects,and macroscopic rheological response to establish more unified and engineering-relevant frameworks for paste rheology in mine backfilling systems.展开更多
The sealing capacity of caprock is critical for preventing CO_(2)migration and ensuring the safety of geological storage.However,existing research lacks a comprehensive overview of its sealing mechanisms and failure r...The sealing capacity of caprock is critical for preventing CO_(2)migration and ensuring the safety of geological storage.However,existing research lacks a comprehensive overview of its sealing mechanisms and failure risks.Here,recent findings on caprock sealing mechanisms,its influencing factors,failure risks,and evaluation methods are summarized.The main results include the following:(i)Caprock sealing mechanisms include capillary,hydraulic,hydrocarbon concentration,and hydrate sealing.(ii)Capillary and hydrate sealing block fluid-phase CO_(2),hydrocarbon concentration sealing prevents diffusive CO_(2),and hydraulic sealing prevents fluid and water-soluble phases.(iii)The sealing capacity is influenced by the storage site,stratigraphic environment,and caprock properties,with breakthrough pressure ranked as follows:gypsum rock>salt rock>mudstone/shale>limestone>silty mudstone.(iv)Diffusion leakage occurs when the diffusion coefficients is less than 10^(-12)m^(2)/s,the seepage leakage ranges between 10^(-8)m^(2)/s and 10^(-12)m^(2)/s,and the fracture leakage is greater than 10^(-8)m^(2)/s.(v)Hydro-mechanical(HM)coupling mechanisms,including CO_(2)diffusion,breakthrough migration,uplift deformation,and fracture flow,are essential for leakage risk simulations.Future research should address sealing mechanisms under complex conditions,define leakage risk thresholds,optimize multiphysical coupling computations,and implement effective engineering solutions to mitigate leakage risk.展开更多
As environmental concerns drive shifts in construction materials,rock is increasingly considered as an alternative to sand,reinforcing the importance of understanding its dynamic properties.This study investigates the...As environmental concerns drive shifts in construction materials,rock is increasingly considered as an alternative to sand,reinforcing the importance of understanding its dynamic properties.This study investigates the effect of water content on the small-strain dynamic properties of basalt samples using free-free laboratory testing.Free-free testing,which requires minimal equipment and preparation,provides an efficient and low-cost method for determining key dynamic properties,including three wave velocities(V_(s),V_(p),and V_(c)),material damping ratios,and Poisson's ratios.These properties are crucial for numerical modeling in earthquake analyses and geotechnical site characterization.The test consists of three components:(1)direct travel-time measurement,(2)torsional resonance testing,and(3)compressional resonance testing.A total of 20 rock samples were tested under systematically controlled water contents,ranging from fully dried to saturated,to quantify the effects on Poisson's ratio and material damping ratios.The results showed significant increases in both parameters with rising water content.The Poisson's ratio increased by up to 320%for aphanitic basalt and 150%for vesicular basalt,while the damping ratio rose up to 30-fold(D_(c,min))and 16-fold(D_(s,min)).These findings highlight the critical need to incorporate consideration of water content when characterizing dynamic rock properties for seismic and geotechnical analyses.The practical applicability of this research lies in improving in situ property interpretation and enhancing seismic design reliability by providing engineers with precise relationships between water content and dynamic rock behavior.展开更多
Water-sand gushing(WSG)disasters in confinedaquifers pose significantchallenges to the utilization of deep underground spaces in soft soil areas.Since few studies have considered the impact of confined aquifer thickne...Water-sand gushing(WSG)disasters in confinedaquifers pose significantchallenges to the utilization of deep underground spaces in soft soil areas.Since few studies have considered the impact of confined aquifer thickness and confinedwater pressure on WSG disasters,a novel visual model test system was developed to investigate the influencingcharacteristics and mechanisms of the two aforementioned factors.The test results showed that the WSG process in clay aquiclude-confinedaquifer composite strata exhibits two prominent stages.First,the sand loss zone expands vertically in an ellipsoid shape.Then,it expands horizontally once the ellipsoid reaches the boundary of the clay layer.The sand loss continues until the overlying clay sinks to the bottom to clog the gushing crack,creating a large sinkhole at the surface.Increasing the confinedaquifer thickness can increase the vertical expansion of the ellipsoid and delay the clay-clogging effects,thereby considerably increasing the severity of sand loss,stratum deformation,and surface settlement.An increase in the confinedwater pressure markedly increases the hydraulic gradient along the seepage path,which contributes to increasing the gushing rates of water and sand.As a result,substantial sand loss occurs before the clay clogs the gushing crack,inducing more cracks and deeper sinkholes at the surface.All the aforementioned results provide insights into the effects of confinedaquifer on WSG disasters in clay aquiclude-confinedaquifer composite strata.展开更多
Underground hydrogen storage has gained interest in recent years due to the enormous demand for clean energy.Hydrogen is more diffusive than air,with a smaller density and lower viscosity.These unique properties intro...Underground hydrogen storage has gained interest in recent years due to the enormous demand for clean energy.Hydrogen is more diffusive than air,with a smaller density and lower viscosity.These unique properties introduce distinctive hydrodynamic phenomena in hydrogen storage,one of which is fingering.Fingering could induce the fluid trapped in small clusters of pores,leading to a dramatic decrease in hydrogen saturation and a lower recovery rate.In this study,numerical simulations are performed at the microscopic scale to understand the evolution of hydrogen saturation and the impacts of injection and withdrawal cycles.Two sets of micromodels with different porosity(0.362 and 0.426)and minimum sizes of pore throats(0.362 mm and 0.181 mm)are developed in the numerical model.A parameter analysis is then conducted to understand the influence of injection velocity(in the range of 10^(-2)m/s to 10^(-5)m/s)and porous structure on the fingering pattern,followed by an image analysis to capture the evolution of the fingering pattern.Viscous fingering,capillary fingering,and crossover fingering are observed and identified under different boundary conditions.The fractal dimension,specific area,mean angle,and entropy of fingers are proposed as geometric descriptors to characterize the shape of the fingering pattern.When porosity increases from 0.362 to 0.426,the saturation of hydrogen increases by 26.2%.Narrower pore throats elevate capillary resistance,which hinders fluid invasion.These results underscore the importance of pore structures and the interaction between viscous and capillary forces for hydrogen recovery efficiency.This work illuminates the influence of the pore structures and the fluid properties on the immiscible displacement of hydrogen and can be further extended to optimize the injection strategy of hydrogen in underground hydrogen storage.展开更多
While injection-induced seismicity has been widely studied,its implications for CO_(2)geological storage require reevaluation due to distinct fluid-rock interactions.This study develops a coupled hydromechanical model...While injection-induced seismicity has been widely studied,its implications for CO_(2)geological storage require reevaluation due to distinct fluid-rock interactions.This study develops a coupled hydromechanical model incorporating rate-and-state friction laws to investigate fault reactivation mechanisms during early-stage CO_(2)injection.The competing effects of pore pressure diffusion and fluid pressurization are systematically investigated,considering three key factors:permeability variations within fault damage zones,normal stress variation coefficients,and injection parameters.Numerical simulations reveal that slower CO_(2)migration causes limited pressure perturbation(<0.3 MPa over 15 d)compared to single-phase fluid injection.Fluid pressurization enhances fault strength and delays reactivation,though this stabilizing effect diminishes in low-permeability damage zones.Highly permeable damage zones promote larger rupture areas despite strengthening from pressurization,as reduced effective stress accelerates failure.Paradoxically,while fluid pressurization increases fault strength,it simultaneously elevates seismic risk through amplified stress drops during slip events.Temporal analysis shows that fluid pressurization dominates initial fault response,while sustained pore pressure diffusion ultimately drives reactivation.Increased normal stress variation coefficients and injection rates accelerate localized rupture initiation but restrict propagation due to non-critically stressed states.This discrepancy demonstrates that regions with positive Coulomb failure stress changes do not correlate well with actual slip zones.These findings highlight the critical interplay between transient pressurization effects and progressive pressure diffusion during early CO_(2)injection phases,providing crucial insights for seismic risk management in CO_(2)storage projects.展开更多
Excessive blasting-induced vibration during drilling-and-blasting excavation of deep tunnels can trigger geological hazards and compromise the stability of both the rock mass and support structures.This study focused ...Excessive blasting-induced vibration during drilling-and-blasting excavation of deep tunnels can trigger geological hazards and compromise the stability of both the rock mass and support structures.This study focused on the deep double-line Sejila Mountain tunnel to systematically analyze the spatial response of blasting-induced vibration and to develop a prediction model through field tests and numerical simulations.The results revealed that the presence of a cross passage significantly altered propagation paths and the spatial distribution of blasting-induced vibration velocity.The peak particle velocity(PPV)at the cross-passage corner was amplified by approximately 1.92 times due to wave reflection and geometric focusing.Blasting-induced vibration waves attenuated non-uniformly across the tunnel cross-section,where PPV on the blast-face side was 1.54–6.56 times higher than that on the opposite side.We propose an improved PPV attenuation model that accounts for the propagation path effect.This model significantly improved fitting accuracy and resolved anomalous parameter(k and a)estimates in traditional equations,thereby improving prediction reliability.Furthermore,based on the observed spatial distribution of blasting-induced vibration,optimal monitoring point placement and targeted vibration control measures for tunnel blasting were discussed.These findings provide a scientific basis for designing blasting schemes and vibration mitigation strategies in deep tunnels.展开更多
With the increasing depth and intensity of coal mining operations,high-energy mine tremors have become a major trigger for rockburst disasters,posing severe threats to mine safety.Conventional rockburst risk assessmen...With the increasing depth and intensity of coal mining operations,high-energy mine tremors have become a major trigger for rockburst disasters,posing severe threats to mine safety.Conventional rockburst risk assessment methods either lack real-time adaptability or rely heavily on qualitative microseismic data analysis,limiting their effectiveness in dynamic early warning.To address these limitations,this study proposed a predictive framework for rockburst risk assessment by integrating ensemble learning algorithms with Bayesian optimization.A dataset was constructed using a sliding time window approach,linking the highest MS energy in the subsequent days with predefined risk levels.Both undersampling and oversampling strategies were employed to mitigate class imbalance,and their performance was evaluated.Three ensemble models,i.e.CatBoost,Random Forest,and LightGBM,were developed,and their hyperparameters were optimized using Bayesian techniques to enhance predictive performance.The models were validated using MS data from the 6303 and 6306 working faces at the Dongtan Coal Mine.All three ensemble models outperformed conventional classification methods,particularly in accurately predicting high-risk categories.Among them,the CatBoost model exhibited the best performance,with an accuracy of 89.47%and an F1¯-score of 90.62%.Furthermore,SHapley Additive exPlanations analysis was used to enhance model interpretability,identifying key MS indicators influencing rockburst risk predictions.This study provides a systematic approach for leveraging MS data and machine learning to improve an early warning system for rockburst hazards,offering valuable insights for underground mining safety management.展开更多
Large-scale geological energy storage plays a crucial role in balancing the intermittency of renewable energy.As an energy storage medium,soaked sandstone has a wide range of applications in geological energy storage....Large-scale geological energy storage plays a crucial role in balancing the intermittency of renewable energy.As an energy storage medium,soaked sandstone has a wide range of applications in geological energy storage.Understanding the damage characteristics in soaked sandstones is essential for ensuring the stability and longevity of these energy storage systems.This study involved multi-stage cyclic loading tests conducted on soaked sandstone to explore the damage evolution throughout the loading process.The findingsreveal several important insights:(1)The plastic hysteresis loops observed during multi-stage cyclic loading evolved from dense to sparse.An increase in stress level led to greater damage in the rock,as evidenced by an increase in accumulated peak/plastic strains.(2)Energy density and stress level are related by quadratic polynomial relationships.The elastic and dissipated energy densities are related by a linear law.The average energy storage coefficientdecreased by up to 24.1%with increasing stress amplitude,reflectingchanges in energy dynamics within the samples.(3)AE counts,amplitude,and frequency provided critical insights into rock damage and fracture patterns.The greater the loading rate and stress amplitude,the lower the proportion of high-amplitude,high-peak frequency,and shear-type fractures.Increasing stress amplitude caused a maximum 16.63%reduction in the AE bvalue,indicating shifts in fracture behavior under varying stress conditions.(4)The increase in loading rate and stress amplitude promotes the transformation of micropores and mesopores to macropores/microcracks.(5)Damage variables,definedin terms of cumulative dissipation energy,aligned closely with the fatigue damage model under multi-stage cyclic loading.Accelerated damage primarily occurred during the finalstages of fatigue loading,highlighting critical periods in the degradation of soaked sandstones.This study can offer guidance for designing operational parameters for energy storage geological bodies dominated by soaked sandstones.展开更多
To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-r...To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-ray computed tomography were combined to obtain the strain distribution over the sample surface and internal fractures of the samples.The Gini and skewness(G-S)coefficients were used to quantify strain localization during tests,where the Gini coefficient reflects the degree of clustering of elements with high strain values,i.e.,strain localization/delocalization.The strain localization-induced asymmetry of data distribution is quantified by the skewness coefficient.A precursor to granite failure is defined by the rapid and simultaneous increase of the G-S coefficients,which are calculated from strain increment,giving an earlier warning of failure by about 8%peak stress than those from absolute strain values.Moreover,the process of damage accumulation due to stress-driven crack propagation in Beishan granite is different at various confining pressures as the stress exceeds the crack initiation stress.Concretely,strain localization is continuous until brittle failure at higher confining pressure,while both strain localization and delocalization occur at lower confining pressure.Despite the different stress conditions,a similar statistical characteristic of strain localization during the creep stage is observed.The Gini coefficient increases,and the skewness coefficient decreases slightly as the creep stress is below 95%peak stress.When the accelerated strain localization begins,the Gini and skewness coefficients increase rapidly and simultaneously.展开更多
Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoret...Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.展开更多
基金Projects(2013BAB02B01,2013BAB02B03)supported by the National Key Technologies R&D Program of ChinaProjects(41072224,41272347)supported by the National Natural Science Foundation of China
文摘Geomechanical parameters are complex and uncertain.In order to take this complexity and uncertainty into account,a probabilistic back-analysis method combining the Bayesian probability with the least squares support vector machine(LS-SVM) technique was proposed.The Bayesian probability was used to deal with the uncertainties in the geomechanical parameters,and an LS-SVM was utilized to establish the relationship between the displacement and the geomechanical parameters.The proposed approach was applied to the geomechanical parameter identification in a slope stability case study which was related to the permanent ship lock within the Three Gorges project in China.The results indicate that the proposed method presents the uncertainties in the geomechanical parameters reasonably well,and also improves the understanding that the monitored information is important in real projects.
文摘Under the background of rapid economic development, the construction industry has entered a new stage of development, and the number of high-rise buildings is on the rise. However, due to the influence of geological conditions in the whole construction process of the project, the geotechnical slope construction faces many problems, especially the stability of the slope. If the slope construction quality cannot be guaranteed, the engineering construction of the whole project will be affected. In geotechnical engineering, slope reinforcement engineering has strong complexity and many influencing factors. It is necessary to select appropriate construction technology in combination with geological conditions in order to better ensure the construction quality. Compared with anti slide pile, anchor bolt support and other construction technologies, prestressed anchor cable construction technology has more significant advantages in construction quality, construction efficiency and greening, which is worthy of wide application.
基金support from the Key R&D Program Project of Hubei Province of China(Grant No.2023BCB074)the National Natural Science Foundation of China(Grant No.42307232).
文摘This study aims to prepare ternary all-solid-waste cementitious materials to completely replace ordinary Portland cement(OPC).Ground granulated blast-furnace slag(GGBS),carbide slag(CS),sulfate solid waste phosphogypsum(PG),electrolytic manganese residue(EMR)and desulfurized gypsum(DG)were used as raw materials to prepare GGBS-PG-CS(GPC),GGBS-EMR-CS(GEC)and GGBS-DG-CS(GDC)ternary all-solid-waste cementitious materials.Macro and microscopic tests were carried out to reveal the mechanical properties and microscopic characteristics,as well as to quantitatively evaluate the environmental and economic benefits.The results show that the optimal ratios of GPC,GEC and GDC are 80:18:2,60:36:4 and 80:18:2,respectively.The corresponding 28 d-unconfined compressive strength(UCS)are 1.62,1.22 and 1.01 times that of OPC,respectively.Carbon emissions and costs per unit strength can be reduced by more than 97%and 57%,respectively.Microscopic analysis shows that the incorporation of sulfate solid waste can synergistically activate GGBS with CS to induce the growth of more needle-like ettringite(AFt),which filled the internal pores and improved the strength of the cementitious material.The better mechanical properties of solidified engineering sediment waste(ESW)also confirm the feasibility of replacing OPC.In summary,this study developed all-solid-waste cementitious materials with excellent mechanical performance,low costs and carbon emissions,which provided a sustainable and economic solution for ESW stabilization.
基金the German Research Foundation (DFG) in the frame of the DFG Priority Program "Network-based Co-operative Planning Processes in Structural Engineering" which is gratefully acknowledged here
文摘An internet-based information and monitoring platform for the specific requirements of geotechnical engineering projects is presented. The platform is based on a hybrid-model approach consisting of a model-based information management system and a resource management system, the latter also referred to as DCMS. Project key information can be accessed via the main user interface, the 'graphical navigator'. The graphical navigator provides also a direct access to additional information in the DCMS. Prompt reac-tion in exceptional situations as well as in daily work gets an extensive support. In practical applications it has been proven that this platform seems to be an adequate tool especially for risk assessment and management in geotechnical engineering projects. Components and advantages of the platform as well as ex periences from the applications are presented and discussed in the paper.
文摘Landslides triggered by heavy rainfall pose a serious threat globally, endangering infrastructure and lives. Many previous landslide studies lack comprehensiveness and site specificity. Thus, a comprehensive investigation is essential to understand the failure mechanisms and contributing factors for assessing potential future hazards. This study aims to investigate the debris flow landslide that occurred in Kavalappara, Kerala, India, on August 8, 2019, through an integrated approach combining geophysical test, weathering characterization, geotechnical, and numerical analyses. Shear wave velocity(V_s) was determined using the Multi-Channel Analysis of Surface Waves(MASW) test to obtain the substrata of the slope. Residual and unsaturated soil properties were obtained through ring shear and dew point potentiometer tests. The mineralogical composition of the soil was identified using Field-Emission Scanning Electron Microscopy(FE-SEM), Energy Dispersive XRay Analysis(EDAX), and X-Ray Diffraction(XRD) patterns. These investigation results focused on slope stability during rainfall infiltration using Limit Equilibrium(LEM) and Finite Element Analysis(FEM) for both low and high-intensity rainfall. Finally, the progressive failure mechanism of the landslide was analysed using the Finite Difference program(FDM). The soil profile showed a variation from loose to dense, with a V_(s) range of 172.85 m/s to 440.53 m/s. No rock layers were identified down to a depth of 15 m. The landslide area consists of migmatite as a parent rock, and the soil was identified as silty clay, comprising quartz and clay minerals. The FEM and LEM analyses reveal that the factor of safety was reduced to 0.83 due to increased pore water pressure and the degree of saturation. The pore water pressure ratio(r_(u)), estimated at 0.32, was used in the FDM. The landslide, initiated at r_u of 0.35, reached maximum velocities of 15.4 m/s horizontally and 12.4 m/s vertically. This study helps disaster management to analyse debris flow and find effective mitigation strategies for hilly areas.
基金supported by the National Natural Science Foundation of China(Nos.42107211 and U23A20651)the Natural Science Foundation of Sichuan Province(No.2025ZNSFSC0097)。
文摘Layered rock masses represent complex geological formations commonly encountered in the surrounding rock of deep engineering excavations(Hou et al.,2019;Xu et al.,2017;Yang C H et al.,2009;Xian and Tan,1989).These rock masses are predominantly composed of sedimentary,para-metamorphic,and volcanic rock types,characterized by a set of prominent,primary bedding structural planes(layers)exhibiting relatively consistent orientations and significant spatial continuity.
基金funding support from the National Natural Science Foundation of China(Grant No.42477178)the National Key Research and Development Program of China(Grant No.2023YFC3709600)the Primary Research and Development Plan of Anhui Province(Grant No.2023t07020018).
文摘Acid mine drainage(AMD)leachate is a global pollutant issue that impacts groundwater environment quality.This study investigated the feasibility of a composite biopolymer-amended bentonite as a geosynthetic clay liner core material to contain AMD leachate.The real AMD leachate with a pH of 3.1,sourced from an acidic pyrite tailings site,was employed as a specific test leachate used in this study.The composite biopolymer was composed of welan gum(WG)and xanthan gum(XG)at different dry weight-based ratios.Modified fluid loss(MFL)tests were conducted to evaluate hydraulic conductivity(k)of bentonites to optimize WG:XG ratio.Rheological properties of biopolymer solutions were measured,serving as indicative parameters of biopolymer elution.The results indicated biopolymer-amended bentonites with the WG:XG ratio of 8:2 possessed lowest k(1.5×10^(−11)m/s to 7.2×10^(−11)m/s),lower than unamended bentonite(1.2×10^(−10)m/s to 8.6×10^(−10)m/s)in the AMD leachate condition.In addition,biopolymer solutions with WG:XG ratio of 8:2 exhibited highest viscosity.Thermogravimetric analysis,ultraviolet–visible spectroscopy,and Fourier transform infrared spectroscopy were conducted on the composite biopolymer,revealing that WG and XG interacted via physical cross-linking.Additionally,scanning electron microscopy and atomic force microscopy images indicated that a physical cross-linking and dense network structure conformation was developed in the composite biopolymer hydrogel at the WG:XG ratio of 8:2.The results demonstrate that the composite biopolymer is a promising low-carbon amendment material for enhancing containment performance of bentonite used in geosynthetic clay liners to contain AMD leachate.
基金funded by the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A20671)the Major Project of Inner Mongolia Science and Technology(Grant No.2021ZD0034)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engi-neering(Grant No.Z021003).
文摘The dynamic evolution of fracture permeability presents a critical scientific challenge in rock masses.Understanding the mechanisms of rock mass permeability evolution is vital for engineering project design and operations.By integrating the discrete element method(DEM)with the finite element method(FEM),a numerical simulation framework for shear seepage in rough fractured shale has been developed to investigate the dynamic mechanisms of permeability evolution under varying confining pressures and during the shearing process.Numerical simulations were conducted on rough fractured samples under effective confining pressures ranging from 5 MPa to 20 MPa to monitor the aperture and permeability evolution of the fracture.The results of the numerical simulation are consistent with the experimental observations,indicating that both the shearing process and confining pressure significantly influence permeability.Moreover,the magnitude of the confining pressure is a crucial factor influencing the trend in permeability changes.Under a confining pressure of 5 MPa,fracture permeability initially increases significantly but decreases post-shearing.In contrast,a continuous decrease in fracture permeability is observed when the confining pressure exceeds 10 MPa.The results of the shear numerical simulation indicate that the confining pressure restricts fracture dilation during shearing,promotes the generation of rock debris,and decreases both the permeability and transmissivity of the fracture.The wear results obtained from numerical simulations are consistent with the experimental patterns and correlate with the joint roughness coefficient(JRC).This study proposed an effective numerical simulation method to reveal the evolution mechanism of fracture flow capacity,taking into account the wear of the fracture surface in shear simulations and the initial stress state of the rock in seepage simulations.This research explains the permeability evolution mechanism of fractured shale from a microscopic perspective,and the proposed numerical simulation method for shear seepage provides a powerful means to uncover the dynamic evolution mechanisms governing fracture permeability.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23A20671 and 12302344)the Creative Groups of Natural Science Foundation of Hubei Province,China(Grant No.2021CFA030).
文摘In recent years,microfluidic technology has emerged as a powerful and innovative tool,attracting significant attention for its ability to provide real-time visualization of CO_(2)flow,mass transfer,and reaction processes in porous media.This review examines the application of microfluidic technology in CO_(2)sequestration in saline aquifers,emphasizing the advantages of saline aquifer for geological sequestration,including safety,high storage capacity,stability,and cost-effectiveness.The materials used for microfluidic chips and the design of microchannels are systematically reviewed,offering forward-looking recommendations for chip selection and microchannel characterization in future research on CO_(2)sequestration in saline aquifer.Based on a detailed analysis of advancements in microfluidic technology,this review highlights key findings related to CO_(2)trapping mechanisms,salt precipitation,and CO_(2)-water-rock chemical interactions within saline aquifers.Although microfluidic technology shows great promise in these areas,this review identifies limitations in current studies and outlines future research directions,aiming to promote further innovation and broader application of microfluidic technology in the field of CO_(2)sequestration in saline aquifer.
基金funded by The Seed Fund Cultivation Project of Ocean College,Zhejiang University(2025BS002)A Project Supported by Scientific Research Fund of Zhejiang University(XY2025056).
文摘The rheological behavior of paste in mine backfilling systems is governed by multiple coupled mechanisms,including particulate structure evolution,time-dependent effects,spatially heterogeneous flow,and scale dependence.As a result,its macroscopic response cannot be adequately described by a single material parameter or purely local constitutive relations.Although significant progress has been made in experimental characterization and empirical modeling,rheological parameters reported under different conditions remain difficult to reconcile,highlighting the limitations of existing models in capturing structural evolution and nonlocal effects.This review provides a concise synthesis of current advances in paste rheology for mine backfilling applications,with emphasis on yield behavior,shear-rate-dependent nonlinear flow response,thixotropy,and shear history effects.The applicability and limitations of commonly used rheological models,including the Bingham and Herschel-Bulkley models,are critically examined.Key factors influencing paste rheology—such as particle gradation,temperature,and chemical additives—are discussed from a structure-controlled perspective.Finally,physics-constrained data-driven approaches are highlighted as a promising direction for improving the description and prediction of complex rheological behavior.Overall,this review emphasizes the need to balance experimental observability,model simplicity,and physical consistency,and highlights the importance of linking microstructural mechanisms,scale effects,and macroscopic rheological response to establish more unified and engineering-relevant frameworks for paste rheology in mine backfilling systems.
基金supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A20671)the Major Project of Inner Mongolia Science and Technology,China(Grant No.2021ZD0034)the Creative Groups of Natural Science Foundation of Hubei Province(Grant No.2021CFA030).
文摘The sealing capacity of caprock is critical for preventing CO_(2)migration and ensuring the safety of geological storage.However,existing research lacks a comprehensive overview of its sealing mechanisms and failure risks.Here,recent findings on caprock sealing mechanisms,its influencing factors,failure risks,and evaluation methods are summarized.The main results include the following:(i)Caprock sealing mechanisms include capillary,hydraulic,hydrocarbon concentration,and hydrate sealing.(ii)Capillary and hydrate sealing block fluid-phase CO_(2),hydrocarbon concentration sealing prevents diffusive CO_(2),and hydraulic sealing prevents fluid and water-soluble phases.(iii)The sealing capacity is influenced by the storage site,stratigraphic environment,and caprock properties,with breakthrough pressure ranked as follows:gypsum rock>salt rock>mudstone/shale>limestone>silty mudstone.(iv)Diffusion leakage occurs when the diffusion coefficients is less than 10^(-12)m^(2)/s,the seepage leakage ranges between 10^(-8)m^(2)/s and 10^(-12)m^(2)/s,and the fracture leakage is greater than 10^(-8)m^(2)/s.(v)Hydro-mechanical(HM)coupling mechanisms,including CO_(2)diffusion,breakthrough migration,uplift deformation,and fracture flow,are essential for leakage risk simulations.Future research should address sealing mechanisms under complex conditions,define leakage risk thresholds,optimize multiphysical coupling computations,and implement effective engineering solutions to mitigate leakage risk.
文摘As environmental concerns drive shifts in construction materials,rock is increasingly considered as an alternative to sand,reinforcing the importance of understanding its dynamic properties.This study investigates the effect of water content on the small-strain dynamic properties of basalt samples using free-free laboratory testing.Free-free testing,which requires minimal equipment and preparation,provides an efficient and low-cost method for determining key dynamic properties,including three wave velocities(V_(s),V_(p),and V_(c)),material damping ratios,and Poisson's ratios.These properties are crucial for numerical modeling in earthquake analyses and geotechnical site characterization.The test consists of three components:(1)direct travel-time measurement,(2)torsional resonance testing,and(3)compressional resonance testing.A total of 20 rock samples were tested under systematically controlled water contents,ranging from fully dried to saturated,to quantify the effects on Poisson's ratio and material damping ratios.The results showed significant increases in both parameters with rising water content.The Poisson's ratio increased by up to 320%for aphanitic basalt and 150%for vesicular basalt,while the damping ratio rose up to 30-fold(D_(c,min))and 16-fold(D_(s,min)).These findings highlight the critical need to incorporate consideration of water content when characterizing dynamic rock properties for seismic and geotechnical analyses.The practical applicability of this research lies in improving in situ property interpretation and enhancing seismic design reliability by providing engineers with precise relationships between water content and dynamic rock behavior.
基金financedby the National Natural Science Foundation of China(Grant No.52090083)the Shanghai Rising-Star Program(Grant No.23QB1404800).
文摘Water-sand gushing(WSG)disasters in confinedaquifers pose significantchallenges to the utilization of deep underground spaces in soft soil areas.Since few studies have considered the impact of confined aquifer thickness and confinedwater pressure on WSG disasters,a novel visual model test system was developed to investigate the influencingcharacteristics and mechanisms of the two aforementioned factors.The test results showed that the WSG process in clay aquiclude-confinedaquifer composite strata exhibits two prominent stages.First,the sand loss zone expands vertically in an ellipsoid shape.Then,it expands horizontally once the ellipsoid reaches the boundary of the clay layer.The sand loss continues until the overlying clay sinks to the bottom to clog the gushing crack,creating a large sinkhole at the surface.Increasing the confinedaquifer thickness can increase the vertical expansion of the ellipsoid and delay the clay-clogging effects,thereby considerably increasing the severity of sand loss,stratum deformation,and surface settlement.An increase in the confinedwater pressure markedly increases the hydraulic gradient along the seepage path,which contributes to increasing the gushing rates of water and sand.As a result,substantial sand loss occurs before the clay clogs the gushing crack,inducing more cracks and deeper sinkholes at the surface.All the aforementioned results provide insights into the effects of confinedaquifer on WSG disasters in clay aquiclude-confinedaquifer composite strata.
基金supported by the National Key Research and Development Project(Grant No.2023YFE0110900)the National Natural Science Foundation of China(Grant Nos.42320104003,42477168).
文摘Underground hydrogen storage has gained interest in recent years due to the enormous demand for clean energy.Hydrogen is more diffusive than air,with a smaller density and lower viscosity.These unique properties introduce distinctive hydrodynamic phenomena in hydrogen storage,one of which is fingering.Fingering could induce the fluid trapped in small clusters of pores,leading to a dramatic decrease in hydrogen saturation and a lower recovery rate.In this study,numerical simulations are performed at the microscopic scale to understand the evolution of hydrogen saturation and the impacts of injection and withdrawal cycles.Two sets of micromodels with different porosity(0.362 and 0.426)and minimum sizes of pore throats(0.362 mm and 0.181 mm)are developed in the numerical model.A parameter analysis is then conducted to understand the influence of injection velocity(in the range of 10^(-2)m/s to 10^(-5)m/s)and porous structure on the fingering pattern,followed by an image analysis to capture the evolution of the fingering pattern.Viscous fingering,capillary fingering,and crossover fingering are observed and identified under different boundary conditions.The fractal dimension,specific area,mean angle,and entropy of fingers are proposed as geometric descriptors to characterize the shape of the fingering pattern.When porosity increases from 0.362 to 0.426,the saturation of hydrogen increases by 26.2%.Narrower pore throats elevate capillary resistance,which hinders fluid invasion.These results underscore the importance of pore structures and the interaction between viscous and capillary forces for hydrogen recovery efficiency.This work illuminates the influence of the pore structures and the fluid properties on the immiscible displacement of hydrogen and can be further extended to optimize the injection strategy of hydrogen in underground hydrogen storage.
基金funded by Joint Funds of the National Natural Science Foundation of China(Grant No.U23A20671)the Major Project of Inner Mongolia Science and Technology(Grant No.2021ZD0034)the Creative Groups of Natural Science Foundation of Hubei Province,China(Grant No.2021CFA030).
文摘While injection-induced seismicity has been widely studied,its implications for CO_(2)geological storage require reevaluation due to distinct fluid-rock interactions.This study develops a coupled hydromechanical model incorporating rate-and-state friction laws to investigate fault reactivation mechanisms during early-stage CO_(2)injection.The competing effects of pore pressure diffusion and fluid pressurization are systematically investigated,considering three key factors:permeability variations within fault damage zones,normal stress variation coefficients,and injection parameters.Numerical simulations reveal that slower CO_(2)migration causes limited pressure perturbation(<0.3 MPa over 15 d)compared to single-phase fluid injection.Fluid pressurization enhances fault strength and delays reactivation,though this stabilizing effect diminishes in low-permeability damage zones.Highly permeable damage zones promote larger rupture areas despite strengthening from pressurization,as reduced effective stress accelerates failure.Paradoxically,while fluid pressurization increases fault strength,it simultaneously elevates seismic risk through amplified stress drops during slip events.Temporal analysis shows that fluid pressurization dominates initial fault response,while sustained pore pressure diffusion ultimately drives reactivation.Increased normal stress variation coefficients and injection rates accelerate localized rupture initiation but restrict propagation due to non-critically stressed states.This discrepancy demonstrates that regions with positive Coulomb failure stress changes do not correlate well with actual slip zones.These findings highlight the critical interplay between transient pressurization effects and progressive pressure diffusion during early CO_(2)injection phases,providing crucial insights for seismic risk management in CO_(2)storage projects.
基金financially supported by the National Natural Science Foundation of China(Nos.42577209 and U22A20239)the Key R&D Program of Hunan Province(No.2024WK2004)the Key Technologies for Accurate Diagnosis and Intelligent Prevention and Control of Slope Hazards in Open pit Mines,181 Major R&D projects of Metallurgical Corporation of China Ltd。
文摘Excessive blasting-induced vibration during drilling-and-blasting excavation of deep tunnels can trigger geological hazards and compromise the stability of both the rock mass and support structures.This study focused on the deep double-line Sejila Mountain tunnel to systematically analyze the spatial response of blasting-induced vibration and to develop a prediction model through field tests and numerical simulations.The results revealed that the presence of a cross passage significantly altered propagation paths and the spatial distribution of blasting-induced vibration velocity.The peak particle velocity(PPV)at the cross-passage corner was amplified by approximately 1.92 times due to wave reflection and geometric focusing.Blasting-induced vibration waves attenuated non-uniformly across the tunnel cross-section,where PPV on the blast-face side was 1.54–6.56 times higher than that on the opposite side.We propose an improved PPV attenuation model that accounts for the propagation path effect.This model significantly improved fitting accuracy and resolved anomalous parameter(k and a)estimates in traditional equations,thereby improving prediction reliability.Furthermore,based on the observed spatial distribution of blasting-induced vibration,optimal monitoring point placement and targeted vibration control measures for tunnel blasting were discussed.These findings provide a scientific basis for designing blasting schemes and vibration mitigation strategies in deep tunnels.
基金funded by the National Natural Science Foundation of China(Grant No.42477208)Natural Science Foundation of Hubei Province,China(Grant No.2024AFA072)Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety(Grant No.SKLGME-JBGS2402).
文摘With the increasing depth and intensity of coal mining operations,high-energy mine tremors have become a major trigger for rockburst disasters,posing severe threats to mine safety.Conventional rockburst risk assessment methods either lack real-time adaptability or rely heavily on qualitative microseismic data analysis,limiting their effectiveness in dynamic early warning.To address these limitations,this study proposed a predictive framework for rockburst risk assessment by integrating ensemble learning algorithms with Bayesian optimization.A dataset was constructed using a sliding time window approach,linking the highest MS energy in the subsequent days with predefined risk levels.Both undersampling and oversampling strategies were employed to mitigate class imbalance,and their performance was evaluated.Three ensemble models,i.e.CatBoost,Random Forest,and LightGBM,were developed,and their hyperparameters were optimized using Bayesian techniques to enhance predictive performance.The models were validated using MS data from the 6303 and 6306 working faces at the Dongtan Coal Mine.All three ensemble models outperformed conventional classification methods,particularly in accurately predicting high-risk categories.Among them,the CatBoost model exhibited the best performance,with an accuracy of 89.47%and an F1¯-score of 90.62%.Furthermore,SHapley Additive exPlanations analysis was used to enhance model interpretability,identifying key MS indicators influencing rockburst risk predictions.This study provides a systematic approach for leveraging MS data and machine learning to improve an early warning system for rockburst hazards,offering valuable insights for underground mining safety management.
基金sponsored by National Natural Science Foundation of China(Grant Nos.U22B6003 and 52304070)Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Chinese Academy of Sciences(Grant No.SKLGME-JBGS2404).
文摘Large-scale geological energy storage plays a crucial role in balancing the intermittency of renewable energy.As an energy storage medium,soaked sandstone has a wide range of applications in geological energy storage.Understanding the damage characteristics in soaked sandstones is essential for ensuring the stability and longevity of these energy storage systems.This study involved multi-stage cyclic loading tests conducted on soaked sandstone to explore the damage evolution throughout the loading process.The findingsreveal several important insights:(1)The plastic hysteresis loops observed during multi-stage cyclic loading evolved from dense to sparse.An increase in stress level led to greater damage in the rock,as evidenced by an increase in accumulated peak/plastic strains.(2)Energy density and stress level are related by quadratic polynomial relationships.The elastic and dissipated energy densities are related by a linear law.The average energy storage coefficientdecreased by up to 24.1%with increasing stress amplitude,reflectingchanges in energy dynamics within the samples.(3)AE counts,amplitude,and frequency provided critical insights into rock damage and fracture patterns.The greater the loading rate and stress amplitude,the lower the proportion of high-amplitude,high-peak frequency,and shear-type fractures.Increasing stress amplitude caused a maximum 16.63%reduction in the AE bvalue,indicating shifts in fracture behavior under varying stress conditions.(4)The increase in loading rate and stress amplitude promotes the transformation of micropores and mesopores to macropores/microcracks.(5)Damage variables,definedin terms of cumulative dissipation energy,aligned closely with the fatigue damage model under multi-stage cyclic loading.Accelerated damage primarily occurred during the finalstages of fatigue loading,highlighting critical periods in the degradation of soaked sandstones.This study can offer guidance for designing operational parameters for energy storage geological bodies dominated by soaked sandstones.
基金supported by the National Natural Science Foundation of China(Grant No.52339001).
文摘To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-ray computed tomography were combined to obtain the strain distribution over the sample surface and internal fractures of the samples.The Gini and skewness(G-S)coefficients were used to quantify strain localization during tests,where the Gini coefficient reflects the degree of clustering of elements with high strain values,i.e.,strain localization/delocalization.The strain localization-induced asymmetry of data distribution is quantified by the skewness coefficient.A precursor to granite failure is defined by the rapid and simultaneous increase of the G-S coefficients,which are calculated from strain increment,giving an earlier warning of failure by about 8%peak stress than those from absolute strain values.Moreover,the process of damage accumulation due to stress-driven crack propagation in Beishan granite is different at various confining pressures as the stress exceeds the crack initiation stress.Concretely,strain localization is continuous until brittle failure at higher confining pressure,while both strain localization and delocalization occur at lower confining pressure.Despite the different stress conditions,a similar statistical characteristic of strain localization during the creep stage is observed.The Gini coefficient increases,and the skewness coefficient decreases slightly as the creep stress is below 95%peak stress.When the accelerated strain localization begins,the Gini and skewness coefficients increase rapidly and simultaneously.
基金support of the National Natural Science Foundation of China(Grant Nos.52179116 and 51991392)the support of Key Deployment Projects of Chinese Academy of Sciences(Grant No.ZDRW-ZS-2021-3).
文摘Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.
