The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is c...The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.展开更多
A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced duri...A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.展开更多
In actual production,deep coal mine roadways are often under typical static-dynamic coupling stress(SDCS)conditions with high ground stress and strong dynamic disturbances.With the increasing number of disasters and a...In actual production,deep coal mine roadways are often under typical static-dynamic coupling stress(SDCS)conditions with high ground stress and strong dynamic disturbances.With the increasing number of disasters and accidents induced by SDCS conditions,the safe and efficient production of coal mines is seriously threatened.Therefore,it is of great practical significance to study the deformation and failure characteristics of the roadway surrounding rock under SDCS.In this paper,the effects of different in-situ stress fields and dynamic load conditions on the surrounding rock are studied by numerical simulations,and the deformation and failure characteristics are obtained.According to the simulation results,the horizontal stress,vertical stress and dynamic disturbance have a positive correlation with the plastic failure of the surrounding rock.Among these factors,the influence of the dynamic disturbance is the most substantial.Under the same stress conditions,the extents of deformation and plastic failure of the roof and ribs are always greater than those of the floor.The effect of horizontal stresses on the roadway deformation is more notable than that of vertical stresses.The results indicate that for the roadway under high-stress conditions,the in-situ stress test must be strengthened first.After determining the magnitude of the in-situ stress,the location of the roadway should be reasonably arranged in the design to optimize the mining sequence.For roadways that are strongly disturbed by dynamic loads,rock supports(rebar/cable bolts,steel set etc.)that are capable of maintaining their effectiveness without failure after certain dynamic loads are required.The results of this study contribute to understanding the characteristics of the roadway deformation and failure under SDCS,and can be used to provide a basis for the support design and optimization under similar geological and geotechnical circumstances.展开更多
Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was gen...Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was generated that can be monitored using microseismic(MS)monitoring techniques.Two MS monitoring systems were established in two typical underground powerhouse caverns featuring distinct geostress levels.The MS b-values associated with rock mass large deformation and their temporal variation are analysed.The results showed that the MS bvalue in course of rock mass deformation was less than 1.0 in the underground powerhouse caverns at a high stress level while larger than 1.5 at a low stress level.Prior to the rock mass deformation,the MS b-values derived from both the high-stress and low-stress underground powerhouse caverns show an incremental decrease over 10%within 10 d.The results contribute to understanding the fracturing characteristics of MS sources associated with rock mass large deformation and provide a reference for early warning of rock mass large deformation in underground powerhouse caverns.展开更多
Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underg...Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.展开更多
Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechan...Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechanism,the complete deformation process of deep rock mass,with a great emphasis on local shear deformation stage,was analyzed in detail.The quasi continuous shear deformation of the deep rock mass is described by a combination of smooth functions:the averaged distribution of the original deformation field,and the local discontinuities along the slip lines.Hence,an elasto-plastic model is established for the shear deformation process,in which the rotational displacement is taken into account as well as the translational component.Numerical analysis method was developed for case study.Deformation process of a tunnel under high earth stress was investigated for verification.展开更多
Based on the measured displacements,the change laws of the effect of distance in phase space on the deformation of mine lane were analyzed and the chaotic time series model to predict the surrounding rocks deformation...Based on the measured displacements,the change laws of the effect of distance in phase space on the deformation of mine lane were analyzed and the chaotic time series model to predict the surrounding rocks deformation of deep mine lane in soft rock by nonlinear theory and methods was established.The chaotic attractor dimension(D) and the largest Lyapunov index(Emax) were put forward to determine whether the deformation process of mine lane is chaotic and the degree of chaos.The analysis of examples indicates that when D>2 and Emax>0,the surrounding rock's deformation of deep mine lane in soft rock is the chaotic process and the laws of the deformation can still be well demonstrated by the method of the reconstructive state space.Comparing with the prediction of linear time series and grey prediction,the chaotic time series prediction has higher accuracy and the prediction results can provide theoretical basis for reasonable support of mine lane in soft rock.The time of the second support in Maluping Mine of Guizhou,China,is determined to arrange at about 40 d after the initial support according to the prediction results.展开更多
A true triaxial apparatus which is composed of three units was presented.The apparatus allows for investigations on deformation and seepage behaviors of a single rock fracture subjected to lateral stress and normal st...A true triaxial apparatus which is composed of three units was presented.The apparatus allows for investigations on deformation and seepage behaviors of a single rock fracture subjected to lateral stress and normal stress.The first unit has three jacks which can apply loads independently in three orthogonal directions.The second unit is used to supply water inflow,control seepage pressure and measure flow velocity in real time.The third unit is for measuring the normal deformation of rock fractures.Some tests for investigating the normal deformation and seepage behaviors of rock fractures subjected to normal and lateral loads on hard granite specimens with an artificial persistent fracture,were introduced.The results show that both the normal deformation and the hydraulic conductivity are influenced not only by the normal stress but also by the lateral stress.It is also shown that the aperture and the hydraulic conductivity decrease with the increasing normal stress but increase with the increasing lateral stress and both the aperture and the hydraulic conductivity obey exponential relationships with the normal stress and the lateral stress.展开更多
To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,th...To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,the influence of structure element position on the anchoring effect of large deformation bolt is discussed.At last,the energy-absorbing support mechanism is discussed.Results show that during the drawing process of normal bolt,drawing force,bolt axial force and interfacial shear stress all gradually increase as increasing the drawing displacement,but when the large deformation bolt enters the structural deformation stage,these three values will keep stable;when the structure element of large deformation bolt approaches the drawing end,the fluctuation range of drawing force decreases,the distributions of bolt axial force and interfacial shear stress of anchorage section are steady and the increasing rate of interfacial shear stress decreases,which are advantageous for keeping the stress stability of the anchorage body.During the working process of large deformation bolt,the strain of bolt body is small,the working resistance is stable and the distributions of bolt axial force and interfacial shear stress are steady.When a rock burst event occurs,the bolt and bonding interface cannot easily break,which weakens the dynamic disaster degree.展开更多
Multi-stage triaxial compression tests for cylindrical red sandstone specimens(diameter of 50 mm,height of 100 mm) were carried out with a rock mechanics testing system and spatial acoustic emission(AE) locations were...Multi-stage triaxial compression tests for cylindrical red sandstone specimens(diameter of 50 mm,height of 100 mm) were carried out with a rock mechanics testing system and spatial acoustic emission(AE) locations were obtained by adopting an AE monitoring system.Based on spatial AE distribution evolution of red sandstone during multi-stage triaxial deformation,the relation between spatial AE events and triaxial deformation of red sandstone was analyzed.The results show that before peak strength,the spatial AE events are not active and distribute stochastically in the specimen,while after peak strength,the spatial AE events are very active and focus on a local region beyond final microscopic failure plane.During multi-stage triaxial deformation with five different confining pressures,the spatial AE distribution evolution in the red sandstone was obtained.The obtained spatial AE locations of red sandstone at the final confining pressure agree very well with the ultimate failure experimental mode.Finally,the influence of confining pressure on the spatial AE evolution characteristics of red sandstone during triaxial deformation was discussed.The AE behavior of red sandstone during multi-stage triaxial deformation is interpreted in the light of the Kaiser effect,which has a significant meaning for predicting the unstable failure of engineering rock mass.展开更多
基金Projects(42307192,41831278)supported by the National Natural Science Foundation of ChinaProject(CKWV20231175/KY)supported by the CRSRI Open Research Program,China。
文摘The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.
基金Project(41941018)supported by the National Natural Science Foundation of China for the Special Project FundingProject(22-JKCF-08)supported by the Study on in-situ Stress Database and 3D in-situ Stress Inversion Technology of Highway Tunnel in Shanxi Province,China+1 种基金Project(2022-JKKJ-6)supported by the Study on Disaster Mechanism and NPR Anchor Cable Prevention and Control of Coal Mining Caving Subsidence in Operating Tunnel in Mountainous Area,ChinaProject(BBJ2024032)supported by the Fundamental Research Funds for the Central Universities(PhD Top Innovative Talents Fund of CUMTB),China。
文摘A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.
基金Projects(52074166,51774195,51704185)supported by the National Natural Science Foundation of ChinaProject(2019M652436)supported by the China Postdoctoral Science Foundation。
文摘In actual production,deep coal mine roadways are often under typical static-dynamic coupling stress(SDCS)conditions with high ground stress and strong dynamic disturbances.With the increasing number of disasters and accidents induced by SDCS conditions,the safe and efficient production of coal mines is seriously threatened.Therefore,it is of great practical significance to study the deformation and failure characteristics of the roadway surrounding rock under SDCS.In this paper,the effects of different in-situ stress fields and dynamic load conditions on the surrounding rock are studied by numerical simulations,and the deformation and failure characteristics are obtained.According to the simulation results,the horizontal stress,vertical stress and dynamic disturbance have a positive correlation with the plastic failure of the surrounding rock.Among these factors,the influence of the dynamic disturbance is the most substantial.Under the same stress conditions,the extents of deformation and plastic failure of the roof and ribs are always greater than those of the floor.The effect of horizontal stresses on the roadway deformation is more notable than that of vertical stresses.The results indicate that for the roadway under high-stress conditions,the in-situ stress test must be strengthened first.After determining the magnitude of the in-situ stress,the location of the roadway should be reasonably arranged in the design to optimize the mining sequence.For roadways that are strongly disturbed by dynamic loads,rock supports(rebar/cable bolts,steel set etc.)that are capable of maintaining their effectiveness without failure after certain dynamic loads are required.The results of this study contribute to understanding the characteristics of the roadway deformation and failure under SDCS,and can be used to provide a basis for the support design and optimization under similar geological and geotechnical circumstances.
基金Projects(51809221,51679158)supported by the National Natural Science Foundation of ChinaProject(KFJJ20-06M)supported by the State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology),China。
文摘Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was generated that can be monitored using microseismic(MS)monitoring techniques.Two MS monitoring systems were established in two typical underground powerhouse caverns featuring distinct geostress levels.The MS b-values associated with rock mass large deformation and their temporal variation are analysed.The results showed that the MS bvalue in course of rock mass deformation was less than 1.0 in the underground powerhouse caverns at a high stress level while larger than 1.5 at a low stress level.Prior to the rock mass deformation,the MS b-values derived from both the high-stress and low-stress underground powerhouse caverns show an incremental decrease over 10%within 10 d.The results contribute to understanding the fracturing characteristics of MS sources associated with rock mass large deformation and provide a reference for early warning of rock mass large deformation in underground powerhouse caverns.
基金Project(50490274) supported by the National Natural Science Foundation of ChinaProject(200516) supported by Hunan Transportation Science and Technology
文摘Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.
基金Project(50825403) supported by the National Science Fund for Distinguished Young ScholarsProject(2010CB732003) supported by the National Key Basic Research Program of ChinaProject(51021001) supported by the Science Fund for Creative Research Group of the National Natural Science Foundation of China
文摘Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechanism,the complete deformation process of deep rock mass,with a great emphasis on local shear deformation stage,was analyzed in detail.The quasi continuous shear deformation of the deep rock mass is described by a combination of smooth functions:the averaged distribution of the original deformation field,and the local discontinuities along the slip lines.Hence,an elasto-plastic model is established for the shear deformation process,in which the rotational displacement is taken into account as well as the translational component.Numerical analysis method was developed for case study.Deformation process of a tunnel under high earth stress was investigated for verification.
基金Project(50490274) supported by the National Natural Science Foundation of China
文摘Based on the measured displacements,the change laws of the effect of distance in phase space on the deformation of mine lane were analyzed and the chaotic time series model to predict the surrounding rocks deformation of deep mine lane in soft rock by nonlinear theory and methods was established.The chaotic attractor dimension(D) and the largest Lyapunov index(Emax) were put forward to determine whether the deformation process of mine lane is chaotic and the degree of chaos.The analysis of examples indicates that when D>2 and Emax>0,the surrounding rock's deformation of deep mine lane in soft rock is the chaotic process and the laws of the deformation can still be well demonstrated by the method of the reconstructive state space.Comparing with the prediction of linear time series and grey prediction,the chaotic time series prediction has higher accuracy and the prediction results can provide theoretical basis for reasonable support of mine lane in soft rock.The time of the second support in Maluping Mine of Guizhou,China,is determined to arrange at about 40 d after the initial support according to the prediction results.
基金Projects(50809069,10872207) supported by the National Natural Science Foundation of ChinaProject(2009CAD017) supported by Outstanding Youth of Hubei Province,China
文摘A true triaxial apparatus which is composed of three units was presented.The apparatus allows for investigations on deformation and seepage behaviors of a single rock fracture subjected to lateral stress and normal stress.The first unit has three jacks which can apply loads independently in three orthogonal directions.The second unit is used to supply water inflow,control seepage pressure and measure flow velocity in real time.The third unit is for measuring the normal deformation of rock fractures.Some tests for investigating the normal deformation and seepage behaviors of rock fractures subjected to normal and lateral loads on hard granite specimens with an artificial persistent fracture,were introduced.The results show that both the normal deformation and the hydraulic conductivity are influenced not only by the normal stress but also by the lateral stress.It is also shown that the aperture and the hydraulic conductivity decrease with the increasing normal stress but increase with the increasing lateral stress and both the aperture and the hydraulic conductivity obey exponential relationships with the normal stress and the lateral stress.
基金Project(2019SDZY02)supported by the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research Development Program,ChinaProject(51904165)supported by the National Natural Science Foundation of ChinaProject(ZR2019QEE026)supported by the Shandong Provincial Natural Science Foundation,China。
文摘To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,the influence of structure element position on the anchoring effect of large deformation bolt is discussed.At last,the energy-absorbing support mechanism is discussed.Results show that during the drawing process of normal bolt,drawing force,bolt axial force and interfacial shear stress all gradually increase as increasing the drawing displacement,but when the large deformation bolt enters the structural deformation stage,these three values will keep stable;when the structure element of large deformation bolt approaches the drawing end,the fluctuation range of drawing force decreases,the distributions of bolt axial force and interfacial shear stress of anchorage section are steady and the increasing rate of interfacial shear stress decreases,which are advantageous for keeping the stress stability of the anchorage body.During the working process of large deformation bolt,the strain of bolt body is small,the working resistance is stable and the distributions of bolt axial force and interfacial shear stress are steady.When a rock burst event occurs,the bolt and bonding interface cannot easily break,which weakens the dynamic disaster degree.
基金Project(2014CB046905)supported by the National Basic Research Program of ChinaProject(2014YC10)supported by the Fundamental Research Funds for the Central Universities,China
文摘Multi-stage triaxial compression tests for cylindrical red sandstone specimens(diameter of 50 mm,height of 100 mm) were carried out with a rock mechanics testing system and spatial acoustic emission(AE) locations were obtained by adopting an AE monitoring system.Based on spatial AE distribution evolution of red sandstone during multi-stage triaxial deformation,the relation between spatial AE events and triaxial deformation of red sandstone was analyzed.The results show that before peak strength,the spatial AE events are not active and distribute stochastically in the specimen,while after peak strength,the spatial AE events are very active and focus on a local region beyond final microscopic failure plane.During multi-stage triaxial deformation with five different confining pressures,the spatial AE distribution evolution in the red sandstone was obtained.The obtained spatial AE locations of red sandstone at the final confining pressure agree very well with the ultimate failure experimental mode.Finally,the influence of confining pressure on the spatial AE evolution characteristics of red sandstone during triaxial deformation was discussed.The AE behavior of red sandstone during multi-stage triaxial deformation is interpreted in the light of the Kaiser effect,which has a significant meaning for predicting the unstable failure of engineering rock mass.
