In mining engineering,dynamic loads acting on the surrounding rock induce irreversible damage.The damage is further exacerbated by water exudation from filling bodies or groundwater in the surrounding rock.Understandi...In mining engineering,dynamic loads acting on the surrounding rock induce irreversible damage.The damage is further exacerbated by water exudation from filling bodies or groundwater in the surrounding rock.Understanding the propagation and energy characteristics of stress waves in damaged surrounding rock is essential for improving the stability of underground structures.Hence,in this study,an improved triaxial Split Hopkinson Pressure Bar(SHPB)testing system was used to prepare four sets of impact-damaged and water-soaked specimens with varying length-to-diameter ratios in the laboratory,followed by dynamic triaxial compression testing.Test results indicate that,following dynamic impact and water soaking,the propagation of stress waves in rock is altered.Compared with intact specimens,impact-damaged and water-soaked specimens(IDWS)show a reduction in both transmission and reflection coefficients,thereby enhancing their energy absorption capacity and decreasing transmitted and reflected energy.The length(length-to-diameter ratio)of the specimen and the peak of the incident wave also affect stress wave propagation.Under the same incident peak value,the transmission coefficient increases with larger length-to-diameter ratios,whereas the reflection coefficient decreases.Similarly,the energy carried by the stress wave is influenced by specimen length:as the length grows,the energy absorbed per unit volume declines.When using energy absorbed per unit volume to characterize the dynamic triaxial strength of rock,the length-to-diameter ratio effect on strength is not pronounced.展开更多
The prediction of rock failure,a key fundamental research for addressing mining safety issues(such as mine slope stability and rockburst),faces challenges with traditional methods due to their complex generalization a...The prediction of rock failure,a key fundamental research for addressing mining safety issues(such as mine slope stability and rockburst),faces challenges with traditional methods due to their complex generalization and computational processes that struggle to describe the entire failure process.Consequently,12 prediction models integrating ensemble learning and optimization algorithms were established to predict rock peak stress and failure time using strain,elastic modulus,density,mass,and confining pressure as inputs.Fivefold cross-validation was used to optimize hyperparameters,significantly improving the model's generalization ability,robustness,and stability.Dataset was established through rock mechanics experiments,with strain increments configured at 0.008‰,0.01‰,and 0.012‰ in the test set.The cross-validation optimized particle swarm optimization eXtreme gradient boosting(CV-PSO-XGBoost)model performed best under a strain increment of 0.01‰,and its stress prediction achieved coefficient of determination R2=0.904,mean absolute error(MAE)=4.315,and root mean square error(RMSE)=5.435;while the failure time prediction demonstrated R2=0.811,mean absolute percentage error(MAPE)=7.842%,and MAE=30.343.Finally,SHapley Additive explanations(SHAP)analysis showed strain and stress significantly impact the model,with strain positively predicting failure time,aligning with traditional rock validating reliability.This study provides insights into the research on rock strata stability in mining.展开更多
Quantifying two-phase fluid flow in fractured rocks is essential for resource reutilization in abandoned mines,subsurface energy recovery and underground waste isolation.This study develops a mathematical framework fo...Quantifying two-phase fluid flow in fractured rocks is essential for resource reutilization in abandoned mines,subsurface energy recovery and underground waste isolation.This study develops a mathematical framework for predicting the permeability of rough fracture networks by integrating fractal geometry with single-phase and two-phase seepage theory.A permeability model for rough fracture networks is first established,and its sensitivity to key geometric parameters is analyzed.A second model is then formulated to relate water-phase saturation to measurable variables,enabling the estimation of two-phase permeability from Reynolds number and aperture.Model predictions show deviations of less than 10%from numerical simulations for both single-phase and two-phase flow,demonstrating the accuracy and robustness of the proposed approach.The results highlight the dominant roles of fracture number,tortuosity and aperture in controlling permeability,as well as the influence of flow regimes on relative permeability.The proposed framework provides a practical and physically based method for analyzing multiphase seepage in fractured rock and offers a foundation for further applications to field-scale fractured systems.展开更多
The elastic modulus of rock mass is a fundamental parameter for the surrounding rock stability analysis and the support scheme design.The traditional testing methods are mainly conducted through indoor experiments,whi...The elastic modulus of rock mass is a fundamental parameter for the surrounding rock stability analysis and the support scheme design.The traditional testing methods are mainly conducted through indoor experiments,which require further research for in-situ testing of rock mass elastic modulus.This article conducts multi-type rock mass digital drilling experiments based on the intelligent rotary cutting testing system for rock masses.The response law of drilling parameters to elastic modulus has been clarified.And a rock rotational ratio energy that integrates four types of drilling parameters is proposed.The rock elastic modulus prediction models(RD-Ei models)are established.The experimental results show that the average testing errors of the model based on drilling pressure,drilling torque,and rotational ratio energy are 21.04%,18.84%,and 6.44%,respectively.On this basis,the intelligent drilling explore system of geology is used to carry out rock drilling experiments.The identification of rock interfaces and testing of elastic modulus can be achieved.This study lays a theoretical foundation for real-time quantitative measurement of the surrounding rock elastic modulus on site.展开更多
Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorpo...Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorporates Weibull distributed heterogeneity to a single fracture in rock,and validate it against ceramic quenching and granite acoustic emission experiments.Distance based generalized sensitivity analysis(DGSA)is applied to quantify the influence and interactions of key parameters,revealing the dominant controls on spalling onset,severity,and damage morphology.The results demonstrate that thermal stress dominates crack initiation and propagation,that lateral constraints can significantly delay and suppress spalling,and that material heterogeneity markedly influences peak stress and damage modes within a certain range of thermal expansion coefficient and has multiple effects on thermal spalling.This study provides a theoretical basis for quantitative assessment and parameter optimization of thermal spalling processes in rock masses.展开更多
基金funded by the National Key Research and Development Program of China-2023 Key Special Project(Grant No.2023YFC2907400)the Hunan Provincial Natural Science Foundation for Distinguished Young Scholars(Grant No.2023JJ10072)the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC1173).
摘要In mining engineering,dynamic loads acting on the surrounding rock induce irreversible damage.The damage is further exacerbated by water exudation from filling bodies or groundwater in the surrounding rock.Understanding the propagation and energy characteristics of stress waves in damaged surrounding rock is essential for improving the stability of underground structures.Hence,in this study,an improved triaxial Split Hopkinson Pressure Bar(SHPB)testing system was used to prepare four sets of impact-damaged and water-soaked specimens with varying length-to-diameter ratios in the laboratory,followed by dynamic triaxial compression testing.Test results indicate that,following dynamic impact and water soaking,the propagation of stress waves in rock is altered.Compared with intact specimens,impact-damaged and water-soaked specimens(IDWS)show a reduction in both transmission and reflection coefficients,thereby enhancing their energy absorption capacity and decreasing transmitted and reflected energy.The length(length-to-diameter ratio)of the specimen and the peak of the incident wave also affect stress wave propagation.Under the same incident peak value,the transmission coefficient increases with larger length-to-diameter ratios,whereas the reflection coefficient decreases.Similarly,the energy carried by the stress wave is influenced by specimen length:as the length grows,the energy absorbed per unit volume declines.When using energy absorbed per unit volume to characterize the dynamic triaxial strength of rock,the length-to-diameter ratio effect on strength is not pronounced.
基金financially supported by the State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China(No.SDGZK2410)the National Key R&D Program of China(No.2023YFC2907203)+4 种基金the National Natural Science Foundation of China(Nos.52374087 and U24B2041)the Outstanding Youth Foundation of Henan Province,China(No.252300421202)the Open Fund of State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China(No.SDGZK2410)the Young Backbone Teacher of Henan Province,China(No.2023GGJS057)the Outstanding Youth Foundation of Henan Polytechnic University,China(No.J2024-1)。
摘要The prediction of rock failure,a key fundamental research for addressing mining safety issues(such as mine slope stability and rockburst),faces challenges with traditional methods due to their complex generalization and computational processes that struggle to describe the entire failure process.Consequently,12 prediction models integrating ensemble learning and optimization algorithms were established to predict rock peak stress and failure time using strain,elastic modulus,density,mass,and confining pressure as inputs.Fivefold cross-validation was used to optimize hyperparameters,significantly improving the model's generalization ability,robustness,and stability.Dataset was established through rock mechanics experiments,with strain increments configured at 0.008‰,0.01‰,and 0.012‰ in the test set.The cross-validation optimized particle swarm optimization eXtreme gradient boosting(CV-PSO-XGBoost)model performed best under a strain increment of 0.01‰,and its stress prediction achieved coefficient of determination R2=0.904,mean absolute error(MAE)=4.315,and root mean square error(RMSE)=5.435;while the failure time prediction demonstrated R2=0.811,mean absolute percentage error(MAPE)=7.842%,and MAE=30.343.Finally,SHapley Additive explanations(SHAP)analysis showed strain and stress significantly impact the model,with strain positively predicting failure time,aligning with traditional rock validating reliability.This study provides insights into the research on rock strata stability in mining.
基金supported by the National Natural Science Foundation of China(Nos.52504155 and 52374147)National Key Research and Development Program of China(No.2023YFC3804204)+1 种基金China Postdoctoral Science Foundation(No.2024M753531)Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2024ZB853).
摘要Quantifying two-phase fluid flow in fractured rocks is essential for resource reutilization in abandoned mines,subsurface energy recovery and underground waste isolation.This study develops a mathematical framework for predicting the permeability of rough fracture networks by integrating fractal geometry with single-phase and two-phase seepage theory.A permeability model for rough fracture networks is first established,and its sensitivity to key geometric parameters is analyzed.A second model is then formulated to relate water-phase saturation to measurable variables,enabling the estimation of two-phase permeability from Reynolds number and aperture.Model predictions show deviations of less than 10%from numerical simulations for both single-phase and two-phase flow,demonstrating the accuracy and robustness of the proposed approach.The results highlight the dominant roles of fracture number,tortuosity and aperture in controlling permeability,as well as the influence of flow regimes on relative permeability.The proposed framework provides a practical and physically based method for analyzing multiphase seepage in fractured rock and offers a foundation for further applications to field-scale fractured systems.
基金Project(2024YFC2909500)supported by the National Key Research and Development Program of ChinaProjects(52204260,42277174,U24A2088)supported by the National Natural Science Foundation of ChinaProjects(2024JCCXSB01,2025XJLJ03)supported by the Fundamental Research Funds for the Central Universities,China。
摘要The elastic modulus of rock mass is a fundamental parameter for the surrounding rock stability analysis and the support scheme design.The traditional testing methods are mainly conducted through indoor experiments,which require further research for in-situ testing of rock mass elastic modulus.This article conducts multi-type rock mass digital drilling experiments based on the intelligent rotary cutting testing system for rock masses.The response law of drilling parameters to elastic modulus has been clarified.And a rock rotational ratio energy that integrates four types of drilling parameters is proposed.The rock elastic modulus prediction models(RD-Ei models)are established.The experimental results show that the average testing errors of the model based on drilling pressure,drilling torque,and rotational ratio energy are 21.04%,18.84%,and 6.44%,respectively.On this basis,the intelligent drilling explore system of geology is used to carry out rock drilling experiments.The identification of rock interfaces and testing of elastic modulus can be achieved.This study lays a theoretical foundation for real-time quantitative measurement of the surrounding rock elastic modulus on site.
基金funded by the National Natural Science Foundation of China(Nos.52574100,52574001,and 52311530070)the Major National Science and Technology Project for Deep Earth of China(No.2024ZD1003805)+1 种基金the Fundamental Research Funds for the Central Universities of China(No.FRF-IDRY-20-003,Interdisciplinary Research Project for Young Teachers of USTB)DE gratefully acknowledges support from the G.Albert Shoemaker endowment.
摘要Thermal spalling in heterogeneous rocks under rapid heating poses critical risks to deep mining and geothermal operations.In this study,we develop a coupled thermal-mechanical-damage(TM D)model that explicitly incorporates Weibull distributed heterogeneity to a single fracture in rock,and validate it against ceramic quenching and granite acoustic emission experiments.Distance based generalized sensitivity analysis(DGSA)is applied to quantify the influence and interactions of key parameters,revealing the dominant controls on spalling onset,severity,and damage morphology.The results demonstrate that thermal stress dominates crack initiation and propagation,that lateral constraints can significantly delay and suppress spalling,and that material heterogeneity markedly influences peak stress and damage modes within a certain range of thermal expansion coefficient and has multiple effects on thermal spalling.This study provides a theoretical basis for quantitative assessment and parameter optimization of thermal spalling processes in rock masses.