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
Grouting with water–cement mixtures is the most widely used and cost-effective method for managing excess water inflow during tunnel construction.Due to uncertain geological and hydrological conditions,current grouti...Grouting with water–cement mixtures is the most widely used and cost-effective method for managing excess water inflow during tunnel construction.Due to uncertain geological and hydrological conditions,current grouting design relies heavily on the experience of onsite engineers.Recent advances in machine learning offer a promising alternative to traditional design to predict grout volume and improve grouting efficiency.Here,an artificial neural network(ANN)model was developed using the data set from an operation tunnel of Jurong Rock Caverns in Singapore to showcase an efficient and physics-guided training strategy.The ANN model was refined by incorporating the spatial scenarios,including the number of grouting holes in four quadrants of tunneling faces,the sequence of grouting screens along the tunnel axis,and the order of grouting rounds on the tunneling faces.The results indicate that an improved training strategy should encompass the grouting process,from Round 1 with grouting holes uniformly distributed around the tunnel periphery,to Round 2 with grouting holes drilled midway between neighboring first-round holes,and to Round 3 with grouting holes determined by onsite engineers.This model,trained based on the order of grouting rounds,performs better than the other models,highlighting the importance of establishing machine learning models grounded in physical principles.The finding was verified by the data set from another operation tunnel and concluded with a perspective on future grouting research.展开更多
The production of vanadium-titanium magnetite(VTM)pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process.High-pressure grinding roll(HPGR)pretreatment...The production of vanadium-titanium magnetite(VTM)pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process.High-pressure grinding roll(HPGR)pretreatment process was used to increase the fine-grained content and specific surface area of VTM concentrates,to strengthen the oxidation consolidation process of VTM pellets,and oxidation kinetic experiments were carried out.The results showed that the specific surface area of VTM concentrates was increased from 872 to 1457 cm^(2)/g by HPGR and then pelletising and roasting.With preheating at 1000℃ for 10 min and roasting at 1260℃ for 10 min,the strengths of preheated pellets were increased from 329 to 535 N,and the strengths of roasted pellets were increased from 1010 to 2591 N.The limiting link in the early stage of VTM pellets oxidation was the control of chemical reaction,while the limiting link in the later stage of oxidation was the mixed control of chemical reaction and gas diffusion.The activation energies of VTM pellets before and after HPGR pretreatment were 53.07 and 40.03 kJ/mol in the early stage of oxidation reaction,while the activation energies in the later stage of oxidation were 29.24 and 22.75 kJ/mol,respectively.展开更多
This paper examines how natural gas disperses vertically when high-pressure pipelines with large openings fail in unconfined environments,providing insight into hazardous gas cloud development and behavior.A comprehen...This paper examines how natural gas disperses vertically when high-pressure pipelines with large openings fail in unconfined environments,providing insight into hazardous gas cloud development and behavior.A comprehensive study was conducted using a full-scale field experiment(1,219 mm diameter,12 MPa pressure,100 mm aperture)combined with a validated computational fluid dynamics(CFD)numerical simulation model to systematically analyze the coupling effects of pipeline pressure and ambient wind speed.The results indicate that:(1)Pipeline pressure determines the vertical jet scale,where jet height is positively correlated with pressure;at 12 MPa,the maximum jet height reaches 69.4 m(approximately 2.65 times that at 4 MPa),and the lower explosive limit(LEL)cloud area follows a quadratic polynomial trend.(2)Ambient wind speed significantly alters the diffusion trajectory;at a wind speed of 10 m/s,the LEL gas cloud area expands by 1.69 times compared to calm conditions,while the jet height is suppressed to 29.9%of the calm wind value.(3)Our developed dynamic prediction model for the hazardous gas-cloud region achieves a determination coefficient of 0.975 and maintaining prediction errors maintained within approximately 12%.The proposed empirical correlations and dynamic prediction model provide essential quantitative data support for safety-distance design and emergency-response decision-making for high-pressure natural gas pipelines.展开更多
Debate has persisted over whether the metamorphic basement of the Zhoushan Islands,easternmost Cathaysia Block,is Precambrian.Here,representative metamorphic rocks from the Qushan Islands were investigated using petro...Debate has persisted over whether the metamorphic basement of the Zhoushan Islands,easternmost Cathaysia Block,is Precambrian.Here,representative metamorphic rocks from the Qushan Islands were investigated using petrography,mineral chemistry,phase equilibria modeling and SHRIMP zircon U-Pb dating to constrain their metamorphic evolution and tectonic significance.Both the pelitic granulites(garnet-kyanite-perthite-biotite-quartz)and the mafic granulites(garnet-clinopyroxene-amphibole-plagioclase-quartz)reached high-pressure granulite-facies conditions of 1.2-1.4 GPa/820-900℃,and recorded three metamorphic stages along a clockwise P-T path with post-peak isothermal decompression.This trajectory indicated rapid exhumation of thickened continental crust during collisional orogeny.Metamorphic ages of 254±3 Ma,262±4 Ma and 259±3 Ma were obtained for mafic granulite,pelitic granulite and marble,respectively,and were consistent with the emplacement age of 259±4 Ma for a pegmatite vein.Detrital zircons in metasediments spanned 2706-330 Ma,which constrained the latest deposition to~330 Ma;thus represented mid-Paleozoic sediment metamorphosed during the late Paleozoic rather than Precambrian basement.We conclude that the Indosinian tectonothermal event in the Cathaysia Block had originated from late Paleozoic-early Mesozoic collisional orogeny between the South China Plate to the north and the Indochina Block to the south.展开更多
Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain anal...Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.展开更多
Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow.The behavior of grout,often highly temperature dependent...Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow.The behavior of grout,often highly temperature dependent,is likely to be affected by the elevated ground temperature in deep rock masses.This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting.The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8.When the temperature is up to 35°C,there can be significant improvements in rheological parameters,acceleration of grout setting,and increase in the rheological time dependence of thick cement grout;however,there may also be a slight impact on the initial grout flowability and the nature of shear thinning.The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably.The proposed constitutive model that couples the Burgers model with a fractional derivativebased Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately.The paper provides a valuable reference for optimization of mixture design of cement grouts,thus enhancing deep rock grouting quality and improving safety.展开更多
Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength.Nevertheless,there is a lack of potent numer...Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength.Nevertheless,there is a lack of potent numerical tools for assessing the grouting effectiveness in water-rich fractured strata.In this study,the hydro-mechanical coupled discontinuous deformation analysis(HM-DDA)is inaugurally extended to simulate the grouting process in a water-rich discrete fracture network(DFN),including the slurry migration,fracture dilation,water plugging in a seepage field,and joint reinforcement after coagulation.To validate the capabilities of the developed method,several numerical examples are conducted incorporating the Newtonian fluid and Bingham slurry.The simulation results closely align with the analytical solutions.Additionally,a set of compression tests is conducted on the fresh and grouted rock specimens to verify the reinforcement method and calibrate the rational properties of reinforced joints.An engineering-scale model based on a real water inrush case of the Yonglian tunnel in a water-rich fractured zone has been established.The model demonstrates the effectiveness of grouting reinforcement in mitigating water inrush disaster.The results indicate that increased grouting pressure greatly affects the regulation of water outflow from the tunnel face and the prevention of rock detachment face after excavation.展开更多
High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress aro...High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated die-castings.Herein,the development of non-heat treatment Al alloys is becoming the hot topic.In addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of castings.To achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and Ce.Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation.Our results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased porosity.Meanwhile,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical properties.Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.展开更多
The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment ...The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment on the oxidation and consolidation of ironsand pellets were investigated,and the energy utilization efficiency of HPGR with different roller pressure intensities was evaluated.The results indicate that HPGR pretreatment at 8 MPa improves the ironsand properties,with the specific surface area increasing by 740 cm^(2) g^(-1) and mechanical energy storage increasing by 2.5 kJ mol^(-1),which is conducive to oxidation and crystalline connection of particles.As roller pressure intensity increases to 16 MPa,more mechanical energy of HPGR is applied for crystal activation,with mechanical energy storage further rising by 18.1 kJ mol^(-1).The apparent activation energy for pellet oxidation initially decreases and then increases,reaching a minimum at 12 MPa.Simultaneously,the roasted pellets porosity decreases by 2.8%,while the compressive strength increases by 789 N.At higher roller pressure intensity,the densely connected structure between particles impedes gas diffusion within the pellets,diminishing the beneficial effects of HPGR on pellet oxidation.Moreover,excessive roller pressure intensity decreases the HPGR energy utilization efficiency.The optimal HPGR roller pressure intensity for ironsand is 12 MPa,at which the specific surface area increases by 790 cm^(2) g^(-1),mechanical energy storage increases by 10.6 kJ mol^(-1),the compressive strength of roasted pellets rises to 2816 N,and the appropriate preheating and roasting temperatures decrease by 250 and 125°C,respectively.展开更多
Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temper...Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.展开更多
The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride so...The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.展开更多
Degradable metals,represented by magnesium and magnesium alloys,have attracted significant attention as fracture internal fixation and bone defect repairing materials due to their good biocompatibility,suitable elasti...Degradable metals,represented by magnesium and magnesium alloys,have attracted significant attention as fracture internal fixation and bone defect repairing materials due to their good biocompatibility,suitable elastic modulus and degradable properties.The Mg-3Zn-1Ca-0.5Sr(wt%)alloy is considered a competitor in the biomaterial field thanks to its unique composition of essential nutrients and excellent mechanical properties.However,the presence of coarse second-phase particles in the alloy accelerates its degradation rate and causes excessive gas formation during implantation,which restricts the alloy's potential for clinical device applications.In order to further optimize the properties of the alloy,extrusion combined with high-pressure torsion(HPT)was adopted for deformation processing.The results show that by optimizing the material processing means,the grain can be refined and broken,and the second-phase distribution can be improved,thus improving the microstructure,mechanical properties,and corrosion resistance of the alloy.After 15 cycles of HPT processing,the grains of the alloy are significantly refined to the nanometer scale,reaching approximately 98 nm.Additionally,the second-phase distribution is greatly improved,transforming the original streamlined structure into a more dispersed distribution.This change in microstructure leads to a significant strengthening effect on the alloy,with a noticeable increase in hardness from 60.3 HV in the as-extruded state to 98.5 HV.展开更多
Suction bucket jacket foundations exhibit considerable potential for implementation in deep-sea offshore wind power projects. To address water film formation resulting from negative pressure penetration during constru...Suction bucket jacket foundations exhibit considerable potential for implementation in deep-sea offshore wind power projects. To address water film formation resulting from negative pressure penetration during construction, certain suction bucket jacket foundation projects implement grouting techniques to ensure adequate bearing capacity. This study conducted a large-scale suction bucket foundation grouting model experiment to examine grout flow characteristics and specific phenomena under various grouting pipeline configurations. Comparative analyses of grouting efficiency and quality across different pipeline layouts identified critical influencing factors and their impact on grouting performance. The results demonstrate that the number of grout outlets should be maintained within an optimal range:insufficient outlets enhance the indentation effect and decrease fill efficiency, while excessive outlets necessitate precise spacing for effective distribution. Additionally, grout outlets should be uniformly arranged to reduce segregation and enhance overall grouting quality. This study's findings provide a scientific foundation for optimizing grouting design in suction bucket jacket foundations, with substantial implications for engineering applications.展开更多
Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intell...Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intelligent prediction method for grouting in fractured rock masses based on three core principles:integration of multi-source input features,fracture voxel modeling,and shortest path in sequential grouting.Three categories of data(geological structure data,grouting environmental data,and grouting operation data in the concept of a grouting geological model)are integrated and served as multi-source structured data in the intelligent prediction of grouting.A voxelization model quantifies the spatial characteristics of fractures,with voxel size optimized for capturing grouting paths.A shortest path algorithm based on a hierarchical solution is then developed to calculate grout penetration distances in the process of sequential grouting.A complete analysis framework is established,from the voxelization of the fracture network model to precise voxel classification,ultimately achieving an accurate prediction of grout penetration.The method demonstrates excellent performance on the test set,with validation against numerical methods in single-fracture and sequential grouting scenarios confirming its accuracy and prediction efficiency as hundreds of times faster than numerical methods.Application to the Dongzhuang hydraulic project’s grouting test area further validates its effectiveness in multi-hole grouting scenarios.展开更多
Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations,playing a crucial role in promoting green and low-...Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations,playing a crucial role in promoting green and low-carbon extraction methodologies.In this study,grouting reinforcement processes were examined by conducting grouting experiments on a fractured rock with varying negative pressures(0-100 kPa),followed by uniaxial compression testing of the grout-reinforced bodies.This investigation explored the diffusion patterns of grout under negative pressure and established a constitutive model of damage-bearing capacity for bodies reinforced by negative pressure grouting.It further studied the enhancement effect of negative pressure on the load-bearing capacity of the reinforced bodies and analyzed the instability mechanism of damage and failure in these bodies.The results indicated that the diffusion of grout under negative pressure is influenced by four types of forces,which alter the extent of grout diffusion within the fractured rock mass.Introducing a damage constitutive model that serially connects pore and framework elements characterizes the damage and failure behavior of groutreinforced bodies under different negative pressures.As the negative pressure increases,changes in porosity,water-to-cement ratio,and admixture quantity occur in the grout-reinforced specimens,with the strength mean curve showing a trend of first increasing and then decreasing,reaching a threshold at a negative pressure of 60 kPa.With increasing negative pressure,the negative pressure damage variable decreases and then increases,and the stronger the interfacial microelement connections caused by the negative pressure,the greater the bearing capacity,ultimately manifesting in different failure modes.展开更多
The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,h...The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.展开更多
Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the sur...Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the surrounding rock.The performance of grouting is primarily governed by the flow behavior and diffusion extent of the slurry.This review considers recent advances in the theory and methodology of slurry flow and diffusion in fractured rock.It examines commonly used grout materials,including cement-based,chemical,and composite formulations,each offering distinct advantages for specific geological conditions.Themechanisms of reinforcement vary significantly across materials,requiring tailored application strategies.The rheological properties of grouting slurries,particularly cement-based types,have been widely modeled using classical constitutive approaches.However,the influence of time-and space-dependent viscosity evolution on slurry behavior remains underexplored.Experimental studies have provided valuable insights into slurry diffusion,yet further research is needed to capture real-time behavior under multi-scale and multi-physics coupling conditions.Similarly,current numerical simulations are largely limited to twoand three-dimensional models of single-fracture flow.These models often neglect the complexity of fracture networks and geological heterogeneity,highlighting a need for more realistic and integrated simulation frameworks.Future research should focus on:(1)fine-scale modeling of slurry hydration and mechanical reinforcement processes;(2)cross-scale analysis of slurry flow under coupled thermal,hydraulic,andmechanical fields;and(3)development of realtime,three-dimensional dynamic simulation tools to capture the full grouting process.These efforts will strengthen the theoretical foundation and practical effectiveness of grouting in complex underground environments.展开更多
A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machine...A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machinery.After the end face of the guide sleeve wears out,it still tightly adheres to the sealing valve seat under the pressure difference,achieving automatic wear compensation.Based on fluid-solid coupling technology,the structural strength of the rotary sealing device was checked.The influence of factors on the sealing performance of rotary sealing devices was studied using the control variable method.The results show that as the pressure of water increases,the leakage rate of the sealing device decreases,and after 30 MPa,the leakage rate is almost 0 mL/h.The temperature of the rotating sealing device increases with the increase of rotation speed or pressure,and the temperature is more affected by the rotation speed factor.The frictional torque increases with increasing pressure and is independent of rotational speed.Comprehensive analysis shows that the wear resistance and reliability level of the sealing guide sleeve material is PVDF>PEEK>PE>PA.This study designs a high-pressure automatic compensation wear rotary sealing device and selects the optimal sealing material,providing technical support for the application of high-pressure water jet in mining machinery.展开更多
Perovskite oxynitrides AB(N,O)_(3), a crucial class in materials science, have attracted much attention. By precisely controlling A-and B-site ions and tuning the N/O ratio, new materials with exotic charge states and...Perovskite oxynitrides AB(N,O)_(3), a crucial class in materials science, have attracted much attention. By precisely controlling A-and B-site ions and tuning the N/O ratio, new materials with exotic charge states and intriguing electronic behaviors can be designed and synthesized. In this work, a novel oxynitride perovskite, CeNbO_(2)N, was prepared under high-temperature and high-pressure conditions. The compound crystallizes in an orthorhombic perovskite structure in Pnma symmetry with disordered N/O distribution. The x-ray absorption spectroscopy confirms the presence of a Nb^(4+) state with 4d^(1) electronic configuration in CeNbO_(2)N. As a result, the resistivity of CeNbO_(2)N is sharply reduced compared to its counterpart CeTa^(5+)ON_(2) and other Nb^(5+) compounds. No long-range spin order is found to occur with the temperature down to 2 K in CeNbO_(2)N, while a remarkable negative magnetoresistance effect shows up at lower temperatures, probably due to the magnetic scattering arising from short-range spin correlations.展开更多
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Ministry of Education-Singapore,Grant/Award Number:RG143/23。
文摘Grouting with water–cement mixtures is the most widely used and cost-effective method for managing excess water inflow during tunnel construction.Due to uncertain geological and hydrological conditions,current grouting design relies heavily on the experience of onsite engineers.Recent advances in machine learning offer a promising alternative to traditional design to predict grout volume and improve grouting efficiency.Here,an artificial neural network(ANN)model was developed using the data set from an operation tunnel of Jurong Rock Caverns in Singapore to showcase an efficient and physics-guided training strategy.The ANN model was refined by incorporating the spatial scenarios,including the number of grouting holes in four quadrants of tunneling faces,the sequence of grouting screens along the tunnel axis,and the order of grouting rounds on the tunneling faces.The results indicate that an improved training strategy should encompass the grouting process,from Round 1 with grouting holes uniformly distributed around the tunnel periphery,to Round 2 with grouting holes drilled midway between neighboring first-round holes,and to Round 3 with grouting holes determined by onsite engineers.This model,trained based on the order of grouting rounds,performs better than the other models,highlighting the importance of establishing machine learning models grounded in physical principles.The finding was verified by the data set from another operation tunnel and concluded with a perspective on future grouting research.
基金supports provided from Guangxi Science and Technology Major Project(AA24263047).
文摘The production of vanadium-titanium magnetite(VTM)pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process.High-pressure grinding roll(HPGR)pretreatment process was used to increase the fine-grained content and specific surface area of VTM concentrates,to strengthen the oxidation consolidation process of VTM pellets,and oxidation kinetic experiments were carried out.The results showed that the specific surface area of VTM concentrates was increased from 872 to 1457 cm^(2)/g by HPGR and then pelletising and roasting.With preheating at 1000℃ for 10 min and roasting at 1260℃ for 10 min,the strengths of preheated pellets were increased from 329 to 535 N,and the strengths of roasted pellets were increased from 1010 to 2591 N.The limiting link in the early stage of VTM pellets oxidation was the control of chemical reaction,while the limiting link in the later stage of oxidation was the mixed control of chemical reaction and gas diffusion.The activation energies of VTM pellets before and after HPGR pretreatment were 53.07 and 40.03 kJ/mol in the early stage of oxidation reaction,while the activation energies in the later stage of oxidation were 29.24 and 22.75 kJ/mol,respectively.
基金supported by the National Natural Science Foundation of China(Grant No.52574278)the Xinjiang Uygur Autonomous Region Key R&D Program Project(Grant No.2024B01003).
文摘This paper examines how natural gas disperses vertically when high-pressure pipelines with large openings fail in unconfined environments,providing insight into hazardous gas cloud development and behavior.A comprehensive study was conducted using a full-scale field experiment(1,219 mm diameter,12 MPa pressure,100 mm aperture)combined with a validated computational fluid dynamics(CFD)numerical simulation model to systematically analyze the coupling effects of pipeline pressure and ambient wind speed.The results indicate that:(1)Pipeline pressure determines the vertical jet scale,where jet height is positively correlated with pressure;at 12 MPa,the maximum jet height reaches 69.4 m(approximately 2.65 times that at 4 MPa),and the lower explosive limit(LEL)cloud area follows a quadratic polynomial trend.(2)Ambient wind speed significantly alters the diffusion trajectory;at a wind speed of 10 m/s,the LEL gas cloud area expands by 1.69 times compared to calm conditions,while the jet height is suppressed to 29.9%of the calm wind value.(3)Our developed dynamic prediction model for the hazardous gas-cloud region achieves a determination coefficient of 0.975 and maintaining prediction errors maintained within approximately 12%.The proposed empirical correlations and dynamic prediction model provide essential quantitative data support for safety-distance design and emergency-response decision-making for high-pressure natural gas pipelines.
基金supported by the National Natural Science Foundation of China(42072223)Geological Survey project(DD20221649,DD20231429).
文摘Debate has persisted over whether the metamorphic basement of the Zhoushan Islands,easternmost Cathaysia Block,is Precambrian.Here,representative metamorphic rocks from the Qushan Islands were investigated using petrography,mineral chemistry,phase equilibria modeling and SHRIMP zircon U-Pb dating to constrain their metamorphic evolution and tectonic significance.Both the pelitic granulites(garnet-kyanite-perthite-biotite-quartz)and the mafic granulites(garnet-clinopyroxene-amphibole-plagioclase-quartz)reached high-pressure granulite-facies conditions of 1.2-1.4 GPa/820-900℃,and recorded three metamorphic stages along a clockwise P-T path with post-peak isothermal decompression.This trajectory indicated rapid exhumation of thickened continental crust during collisional orogeny.Metamorphic ages of 254±3 Ma,262±4 Ma and 259±3 Ma were obtained for mafic granulite,pelitic granulite and marble,respectively,and were consistent with the emplacement age of 259±4 Ma for a pegmatite vein.Detrital zircons in metasediments spanned 2706-330 Ma,which constrained the latest deposition to~330 Ma;thus represented mid-Paleozoic sediment metamorphosed during the late Paleozoic rather than Precambrian basement.We conclude that the Indosinian tectonothermal event in the Cathaysia Block had originated from late Paleozoic-early Mesozoic collisional orogeny between the South China Plate to the north and the Indochina Block to the south.
基金supported in part by the National Natural Science Foundation of China Grant 11962006the Natural Science Foundation of Jiangxi Province of China Grant 20232BAB204067.
文摘Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.
基金The Fundamental Research Funds for the Central Universities,Grant/Award Number:YJ2021148National Natural Science Foundation of China,Grant/Award Number:52374132。
文摘Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow.The behavior of grout,often highly temperature dependent,is likely to be affected by the elevated ground temperature in deep rock masses.This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting.The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8.When the temperature is up to 35°C,there can be significant improvements in rheological parameters,acceleration of grout setting,and increase in the rheological time dependence of thick cement grout;however,there may also be a slight impact on the initial grout flowability and the nature of shear thinning.The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably.The proposed constitutive model that couples the Burgers model with a fractional derivativebased Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately.The paper provides a valuable reference for optimization of mixture design of cement grouts,thus enhancing deep rock grouting quality and improving safety.
基金supported by the China Scholarship Council(CSC,Grant No.202108050072)JSPS KAKENHI(Grant No.JP19KK0121)。
文摘Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength.Nevertheless,there is a lack of potent numerical tools for assessing the grouting effectiveness in water-rich fractured strata.In this study,the hydro-mechanical coupled discontinuous deformation analysis(HM-DDA)is inaugurally extended to simulate the grouting process in a water-rich discrete fracture network(DFN),including the slurry migration,fracture dilation,water plugging in a seepage field,and joint reinforcement after coagulation.To validate the capabilities of the developed method,several numerical examples are conducted incorporating the Newtonian fluid and Bingham slurry.The simulation results closely align with the analytical solutions.Additionally,a set of compression tests is conducted on the fresh and grouted rock specimens to verify the reinforcement method and calibrate the rational properties of reinforced joints.An engineering-scale model based on a real water inrush case of the Yonglian tunnel in a water-rich fractured zone has been established.The model demonstrates the effectiveness of grouting reinforcement in mitigating water inrush disaster.The results indicate that increased grouting pressure greatly affects the regulation of water outflow from the tunnel face and the prevention of rock detachment face after excavation.
基金financially supported by the National Natural Science Foundation of China(Nos.52175284 and 52474396)the National Key Research and Development Program of China(No.2022YFB3404201)。
文摘High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated die-castings.Herein,the development of non-heat treatment Al alloys is becoming the hot topic.In addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of castings.To achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and Ce.Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation.Our results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased porosity.Meanwhile,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical properties.Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.
基金financially supported by the General Program of National Natural Science Foundation of China(No.52174330)Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220069)Postgraduate Innovative Project of Central South University(No.1053320214756).
文摘The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment on the oxidation and consolidation of ironsand pellets were investigated,and the energy utilization efficiency of HPGR with different roller pressure intensities was evaluated.The results indicate that HPGR pretreatment at 8 MPa improves the ironsand properties,with the specific surface area increasing by 740 cm^(2) g^(-1) and mechanical energy storage increasing by 2.5 kJ mol^(-1),which is conducive to oxidation and crystalline connection of particles.As roller pressure intensity increases to 16 MPa,more mechanical energy of HPGR is applied for crystal activation,with mechanical energy storage further rising by 18.1 kJ mol^(-1).The apparent activation energy for pellet oxidation initially decreases and then increases,reaching a minimum at 12 MPa.Simultaneously,the roasted pellets porosity decreases by 2.8%,while the compressive strength increases by 789 N.At higher roller pressure intensity,the densely connected structure between particles impedes gas diffusion within the pellets,diminishing the beneficial effects of HPGR on pellet oxidation.Moreover,excessive roller pressure intensity decreases the HPGR energy utilization efficiency.The optimal HPGR roller pressure intensity for ironsand is 12 MPa,at which the specific surface area increases by 790 cm^(2) g^(-1),mechanical energy storage increases by 10.6 kJ mol^(-1),the compressive strength of roasted pellets rises to 2816 N,and the appropriate preheating and roasting temperatures decrease by 250 and 125°C,respectively.
基金supported by the National Natural Science Foundation of China(Grant No.U21B2062)supported by the Key Laboratory for Carbonate Reservoirs of China National Petroleum Corporation。
文摘Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.
基金Funded by a Science and Technology Project from the Ministry of Housing and Urban-Rural Development of the People’s Republic of China(No.2019-K-047)Yangzhou Government-Yangzhou University Cooperative Platform Project for Science and Technology Innovation(No.YZ2020262)。
文摘The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.
基金National Key Research and Development Program of China(2021YFB3701004)。
文摘Degradable metals,represented by magnesium and magnesium alloys,have attracted significant attention as fracture internal fixation and bone defect repairing materials due to their good biocompatibility,suitable elastic modulus and degradable properties.The Mg-3Zn-1Ca-0.5Sr(wt%)alloy is considered a competitor in the biomaterial field thanks to its unique composition of essential nutrients and excellent mechanical properties.However,the presence of coarse second-phase particles in the alloy accelerates its degradation rate and causes excessive gas formation during implantation,which restricts the alloy's potential for clinical device applications.In order to further optimize the properties of the alloy,extrusion combined with high-pressure torsion(HPT)was adopted for deformation processing.The results show that by optimizing the material processing means,the grain can be refined and broken,and the second-phase distribution can be improved,thus improving the microstructure,mechanical properties,and corrosion resistance of the alloy.After 15 cycles of HPT processing,the grains of the alloy are significantly refined to the nanometer scale,reaching approximately 98 nm.Additionally,the second-phase distribution is greatly improved,transforming the original streamlined structure into a more dispersed distribution.This change in microstructure leads to a significant strengthening effect on the alloy,with a noticeable increase in hardness from 60.3 HV in the as-extruded state to 98.5 HV.
文摘Suction bucket jacket foundations exhibit considerable potential for implementation in deep-sea offshore wind power projects. To address water film formation resulting from negative pressure penetration during construction, certain suction bucket jacket foundation projects implement grouting techniques to ensure adequate bearing capacity. This study conducted a large-scale suction bucket foundation grouting model experiment to examine grout flow characteristics and specific phenomena under various grouting pipeline configurations. Comparative analyses of grouting efficiency and quality across different pipeline layouts identified critical influencing factors and their impact on grouting performance. The results demonstrate that the number of grout outlets should be maintained within an optimal range:insufficient outlets enhance the indentation effect and decrease fill efficiency, while excessive outlets necessitate precise spacing for effective distribution. Additionally, grout outlets should be uniformly arranged to reduce segregation and enhance overall grouting quality. This study's findings provide a scientific foundation for optimizing grouting design in suction bucket jacket foundations, with substantial implications for engineering applications.
基金supported by the National Natural Science Foundation of China(Grant No.U23A6018)Science and Technology Program of Hebei(Grant No.E2022202041,2022HBQZYCXY004,242Q9920Z)the project of“Key technologies of seepage control system for large-scale hydraulic projects”was also gratefully appreciated.
文摘Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intelligent prediction method for grouting in fractured rock masses based on three core principles:integration of multi-source input features,fracture voxel modeling,and shortest path in sequential grouting.Three categories of data(geological structure data,grouting environmental data,and grouting operation data in the concept of a grouting geological model)are integrated and served as multi-source structured data in the intelligent prediction of grouting.A voxelization model quantifies the spatial characteristics of fractures,with voxel size optimized for capturing grouting paths.A shortest path algorithm based on a hierarchical solution is then developed to calculate grout penetration distances in the process of sequential grouting.A complete analysis framework is established,from the voxelization of the fracture network model to precise voxel classification,ultimately achieving an accurate prediction of grout penetration.The method demonstrates excellent performance on the test set,with validation against numerical methods in single-fracture and sequential grouting scenarios confirming its accuracy and prediction efficiency as hundreds of times faster than numerical methods.Application to the Dongzhuang hydraulic project’s grouting test area further validates its effectiveness in multi-hole grouting scenarios.
基金the funding support from the Natural Science Foundation of China(Grant No.52130402)the Anhui Province Graduate Education Quality Engineering Project(Grant No.2023cxcysj088)the China Scholarship Council Grants Program(Grant No.202308340082).
文摘Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations,playing a crucial role in promoting green and low-carbon extraction methodologies.In this study,grouting reinforcement processes were examined by conducting grouting experiments on a fractured rock with varying negative pressures(0-100 kPa),followed by uniaxial compression testing of the grout-reinforced bodies.This investigation explored the diffusion patterns of grout under negative pressure and established a constitutive model of damage-bearing capacity for bodies reinforced by negative pressure grouting.It further studied the enhancement effect of negative pressure on the load-bearing capacity of the reinforced bodies and analyzed the instability mechanism of damage and failure in these bodies.The results indicated that the diffusion of grout under negative pressure is influenced by four types of forces,which alter the extent of grout diffusion within the fractured rock mass.Introducing a damage constitutive model that serially connects pore and framework elements characterizes the damage and failure behavior of groutreinforced bodies under different negative pressures.As the negative pressure increases,changes in porosity,water-to-cement ratio,and admixture quantity occur in the grout-reinforced specimens,with the strength mean curve showing a trend of first increasing and then decreasing,reaching a threshold at a negative pressure of 60 kPa.With increasing negative pressure,the negative pressure damage variable decreases and then increases,and the stronger the interfacial microelement connections caused by the negative pressure,the greater the bearing capacity,ultimately manifesting in different failure modes.
基金supported by the National Natural Science Foundation of China,Grant Nos.42477185,41602308the Zhejiang Provincial Natural Science Foundation of China,Grant No.LY20E080005+2 种基金the Zhejiang Province University Students Science and Technology Innovation Program,Grant No.0201310P28the PostGraduate Course Construction Project of Zhejiang University of Science and Technology,Grant No.2021yjskj05the Zhejiang University of Science and Technology Graduate Research and Innovation Fund,Grant No.2023yjskc10.
文摘The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.
基金funded by the National Natural Science Foundation of China[U22A20234]Hubei Province key research and development project[2023BCB121]Wuhan innovation supporting projects[2023020201010079].
文摘Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the surrounding rock.The performance of grouting is primarily governed by the flow behavior and diffusion extent of the slurry.This review considers recent advances in the theory and methodology of slurry flow and diffusion in fractured rock.It examines commonly used grout materials,including cement-based,chemical,and composite formulations,each offering distinct advantages for specific geological conditions.Themechanisms of reinforcement vary significantly across materials,requiring tailored application strategies.The rheological properties of grouting slurries,particularly cement-based types,have been widely modeled using classical constitutive approaches.However,the influence of time-and space-dependent viscosity evolution on slurry behavior remains underexplored.Experimental studies have provided valuable insights into slurry diffusion,yet further research is needed to capture real-time behavior under multi-scale and multi-physics coupling conditions.Similarly,current numerical simulations are largely limited to twoand three-dimensional models of single-fracture flow.These models often neglect the complexity of fracture networks and geological heterogeneity,highlighting a need for more realistic and integrated simulation frameworks.Future research should focus on:(1)fine-scale modeling of slurry hydration and mechanical reinforcement processes;(2)cross-scale analysis of slurry flow under coupled thermal,hydraulic,andmechanical fields;and(3)development of realtime,three-dimensional dynamic simulation tools to capture the full grouting process.These efforts will strengthen the theoretical foundation and practical effectiveness of grouting in complex underground environments.
基金Supported by Jiangsu Provincial Natural Science Foundation(Grant No.BK20231497)Jiangsu Provincial Post graduate Research&Practice Innovation Program(Grant No.KYCX25_2982)+3 种基金China University of Mining and Technology Graduate Innovation Program(Grant No.2025WLKXJ094)National Natural Science Foundation of China(Grant No.51975573)National Key R&D Program of China(Grant No.2022YFC2905600)Priority Academic Program Development of Jiangsu Higher Education Institute of China.
文摘A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machinery.After the end face of the guide sleeve wears out,it still tightly adheres to the sealing valve seat under the pressure difference,achieving automatic wear compensation.Based on fluid-solid coupling technology,the structural strength of the rotary sealing device was checked.The influence of factors on the sealing performance of rotary sealing devices was studied using the control variable method.The results show that as the pressure of water increases,the leakage rate of the sealing device decreases,and after 30 MPa,the leakage rate is almost 0 mL/h.The temperature of the rotating sealing device increases with the increase of rotation speed or pressure,and the temperature is more affected by the rotation speed factor.The frictional torque increases with increasing pressure and is independent of rotational speed.Comprehensive analysis shows that the wear resistance and reliability level of the sealing guide sleeve material is PVDF>PEEK>PE>PA.This study designs a high-pressure automatic compensation wear rotary sealing device and selects the optimal sealing material,providing technical support for the application of high-pressure water jet in mining machinery.
基金Project supported by the National Key R&D Program of China (Grant No. 2021YFA1400300)the National Natural Science Foundation of China (Grant Nos. 12425403, 12261131499, 12304268, 12304159, 11934017, and 11921004)+1 种基金the China Postdoctoral Science Foundation (Grant No. 2023M743741)The synchrotron x-ray diffraction experiments were performed at SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (Grant Nos. 2023B1575, 2023B1976, 2024A1506, and 2024A1695)。
文摘Perovskite oxynitrides AB(N,O)_(3), a crucial class in materials science, have attracted much attention. By precisely controlling A-and B-site ions and tuning the N/O ratio, new materials with exotic charge states and intriguing electronic behaviors can be designed and synthesized. In this work, a novel oxynitride perovskite, CeNbO_(2)N, was prepared under high-temperature and high-pressure conditions. The compound crystallizes in an orthorhombic perovskite structure in Pnma symmetry with disordered N/O distribution. The x-ray absorption spectroscopy confirms the presence of a Nb^(4+) state with 4d^(1) electronic configuration in CeNbO_(2)N. As a result, the resistivity of CeNbO_(2)N is sharply reduced compared to its counterpart CeTa^(5+)ON_(2) and other Nb^(5+) compounds. No long-range spin order is found to occur with the temperature down to 2 K in CeNbO_(2)N, while a remarkable negative magnetoresistance effect shows up at lower temperatures, probably due to the magnetic scattering arising from short-range spin correlations.
