The rock masses in the hydro-fluctuation zone of reservoir banks sustain wettingdrying cycles(WDC),thereby affecting the stability of the reservoir bank slope.In this paper,rock masses with argillaceous siltstone and ...The rock masses in the hydro-fluctuation zone of reservoir banks sustain wettingdrying cycles(WDC),thereby affecting the stability of the reservoir bank slope.In this paper,rock masses with argillaceous siltstone and silty mudstone interbedded in Badong Formation were taken as the research object to investigate the variation of strength parameters of soft and hard interbedded rock masses with WDC and dip angle through laboratory experiments and numerical experiments.Some attempts were made to reveal the mechanical properties deterioration mechanism of interbedded rock masses by quantitatively analyzing the contribution of strength parameters deterioration of hard rocks,soft rocks,and bedding planes to the strength parameters deterioration of rock masses.The results indicate that the logarithmic function could be used to describe the deterioration of each strength parameter of both argillaceous siltstone and silty mudstone and bedding plane with the number of WDC.The strength parameters of interbedded rock masses decrease as the number of WDC increases,with the largest decrease after the first cycle and then slowing down in the later cycles.The strength parameters initially decrease and then increase as the dip angles increase.The impact of deteriorated strength parameters of bedding planes and rocks on the deterioration of strength parameters of interbedded rock masses differs significantly with the dip angle,which can be divided into four typical ranges of different controlling factors.展开更多
In the frost-thaw region,prolonged freezethaw weathering can induce fracture and weaken rock masses,threatening engineering stability.While interbedded rock masses are common in such projects,their failure mechanisms ...In the frost-thaw region,prolonged freezethaw weathering can induce fracture and weaken rock masses,threatening engineering stability.While interbedded rock masses are common in such projects,their failure mechanisms remain insufficiently investigated in freezing and thawing environments.Therefore,this research establishes a particle flow code(PFC2D)model of interlayered rock masses with particular emphasis on the role of thickness variation.The analysis focuses on displacement,crack evolution,contact forces,and uniaxial compressive strength.The findings indicate that:(i)Completing 8 freeze-thaw cycles significantly increases displacement and contact forces,with crack growth accelerating markedly after 16 cycles.As the soft rock layer thickness ratio(Hs/H)increases,the peak contact force decreases by 18.3%,while the number of cracks rises by 48%.Once Hs/H exceeded 0.5,the rate of crack development decelerates.This reflects progressive bond degradation and damage accumulation:microscopic bonds weaken and rupture to form microcracks.Increased soft rock thickness promotes micro-damage accumulation,altering contact forces and intensifying degradation.(ii)Compressive cracks predominantly initiate in soft rock(limestone).After 20 cycles,cracking extends into the hard rock regions.As the Hs/H rises,compressive cracks first increase and then decline,with an overall reduction of 10.8%,while the compressive contact force exhibits a consistent downward trend.This trend indicates that freeze-thaw cycles cause severe microscopic degradation in soft rock,weakening its macroscopic strength and influencing compressive crack development.Increased soft rock thickness alters the stress state,thereby modifying crack propagation.(iii)Uniaxial compressive strength experiences a marked deterioration after 15 freeze-thaw cycles.It follows an exponential decay with increasing Hs/H,culminating in a total strength reduction of 76.9%.This demonstrates that freeze-thaw-induced microscopic damage deteriorates interparticle cohesion,reducing rock mass strength.A higher Hs/H ratio accelerates microscopic damage in the soft rock,causing cohesion to decay nonlinearly and macroscopic strength to drop exponentially.These results provide a theoretical basis for assessing the deformation and failure behaviors of rock masses under cyclic freeze-thaw action.展开更多
Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent...Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.展开更多
Soft and hard interbedded bedding rock slopes,which is prone to failure,are widely distributed in the Three Gorges Reservoir,China.Limit equilibrium method(LEM)is commonly used to analyze the stability of bedding rock...Soft and hard interbedded bedding rock slopes,which is prone to failure,are widely distributed in the Three Gorges Reservoir,China.Limit equilibrium method(LEM)is commonly used to analyze the stability of bedding rock slopes that have a single failure plane.However,this method cannot accurately estimate the stability of soft and hard interbedded bedding reservoir slopes because the strength parameters of a soft and hard interbedded rock mass vary spatially along the bedding plane and deteriorate with time due to periodic fluctuations of reservoir level.A modified LEM is proposed to evaluate the stability evolution of soft and hard interbedded bedding reservoir slopes considering the spatial variation and temporal deterioration of shear strength parameters of rock masses and bedding planes.In the modified LEM,the S-curve model is used to define the spatial variation of shear strength parameters,and general deterioration equations of shear strength parameters with the increasing number of wettingdrying cycles(WDC)are proposed to describe the temporal deterioration.Also,this method is applied to evaluate the stability evolution of a soft and hard interbedded bedding reservoir slope,located at the Three Gorges Reservoir.The results show that neglecting the spatial variation and temporal deterioration of shear strength parameters may overestimate slope stability.Finally,the modified LEM provides useful guidance to reasonably evaluate the long-term stability of soft and hard interbedded bedding reservoir slopes in reservoir area.展开更多
The significant difference between the mechanical properties of soft rock and hard rock results in the complexity of the failure mode of the anti-dip layered slope with soft and hard rock interbedding.In order to reve...The significant difference between the mechanical properties of soft rock and hard rock results in the complexity of the failure mode of the anti-dip layered slope with soft and hard rock interbedding.In order to reveal the landslide mechanism,taking the north slope of Fushun West Open-pit Mine as an example,this paper analyzed the failure mechanism of different landslides with monitoring and field surveys,and simulated the evolution of landslides.The study indicated that when the green mudstone(hard rock)of the anti-dip slope contains siltized intercalations(soft rock),the existence of weak layers not only aggravates the toppling deformation of anti-dip layered slope with high dip,but also causes the shear failure of anti-dip layered slope with stable low dip.The shear failure including subsidence induced sliding and wedge failure mainly exists in the unloading zone of the slope.Its failure depth and failure time were far less than that of toppling failure.In terms of the development characteristics of deformation,toppling deformation has the long-term and progressive characteristics,but shear failure deformation has the abrupt and transient characteristics.This study has deepened the understanding of such slope landslide mechanism,and can provide reference for similar engineering.展开更多
基金supported by the Chinese National Key R&D Program(No.2022YFC3080200)the Chinese National Natural Science Foundation(No.42090054)。
文摘The rock masses in the hydro-fluctuation zone of reservoir banks sustain wettingdrying cycles(WDC),thereby affecting the stability of the reservoir bank slope.In this paper,rock masses with argillaceous siltstone and silty mudstone interbedded in Badong Formation were taken as the research object to investigate the variation of strength parameters of soft and hard interbedded rock masses with WDC and dip angle through laboratory experiments and numerical experiments.Some attempts were made to reveal the mechanical properties deterioration mechanism of interbedded rock masses by quantitatively analyzing the contribution of strength parameters deterioration of hard rocks,soft rocks,and bedding planes to the strength parameters deterioration of rock masses.The results indicate that the logarithmic function could be used to describe the deterioration of each strength parameter of both argillaceous siltstone and silty mudstone and bedding plane with the number of WDC.The strength parameters of interbedded rock masses decrease as the number of WDC increases,with the largest decrease after the first cycle and then slowing down in the later cycles.The strength parameters initially decrease and then increase as the dip angles increase.The impact of deteriorated strength parameters of bedding planes and rocks on the deterioration of strength parameters of interbedded rock masses differs significantly with the dip angle,which can be divided into four typical ranges of different controlling factors.
基金supported by the National Natural Science Foundation of China(Grant Nos.52379100 and 42462030)。
文摘In the frost-thaw region,prolonged freezethaw weathering can induce fracture and weaken rock masses,threatening engineering stability.While interbedded rock masses are common in such projects,their failure mechanisms remain insufficiently investigated in freezing and thawing environments.Therefore,this research establishes a particle flow code(PFC2D)model of interlayered rock masses with particular emphasis on the role of thickness variation.The analysis focuses on displacement,crack evolution,contact forces,and uniaxial compressive strength.The findings indicate that:(i)Completing 8 freeze-thaw cycles significantly increases displacement and contact forces,with crack growth accelerating markedly after 16 cycles.As the soft rock layer thickness ratio(Hs/H)increases,the peak contact force decreases by 18.3%,while the number of cracks rises by 48%.Once Hs/H exceeded 0.5,the rate of crack development decelerates.This reflects progressive bond degradation and damage accumulation:microscopic bonds weaken and rupture to form microcracks.Increased soft rock thickness promotes micro-damage accumulation,altering contact forces and intensifying degradation.(ii)Compressive cracks predominantly initiate in soft rock(limestone).After 20 cycles,cracking extends into the hard rock regions.As the Hs/H rises,compressive cracks first increase and then decline,with an overall reduction of 10.8%,while the compressive contact force exhibits a consistent downward trend.This trend indicates that freeze-thaw cycles cause severe microscopic degradation in soft rock,weakening its macroscopic strength and influencing compressive crack development.Increased soft rock thickness alters the stress state,thereby modifying crack propagation.(iii)Uniaxial compressive strength experiences a marked deterioration after 15 freeze-thaw cycles.It follows an exponential decay with increasing Hs/H,culminating in a total strength reduction of 76.9%.This demonstrates that freeze-thaw-induced microscopic damage deteriorates interparticle cohesion,reducing rock mass strength.A higher Hs/H ratio accelerates microscopic damage in the soft rock,causing cohesion to decay nonlinearly and macroscopic strength to drop exponentially.These results provide a theoretical basis for assessing the deformation and failure behaviors of rock masses under cyclic freeze-thaw action.
基金the support of the National Natural Science Foundation of China(Grant Nos.42207199,52179113,42272333)Zhejiang Postdoctoral Scientific Research Project(Grant Nos.ZJ2022155,ZJ2022156)。
文摘Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.
基金supported by the National Natural Science Foundation of China(Project No.42377182 and 42090054)the National Key R&D Program of China(No.2022YFC3080200)。
文摘Soft and hard interbedded bedding rock slopes,which is prone to failure,are widely distributed in the Three Gorges Reservoir,China.Limit equilibrium method(LEM)is commonly used to analyze the stability of bedding rock slopes that have a single failure plane.However,this method cannot accurately estimate the stability of soft and hard interbedded bedding reservoir slopes because the strength parameters of a soft and hard interbedded rock mass vary spatially along the bedding plane and deteriorate with time due to periodic fluctuations of reservoir level.A modified LEM is proposed to evaluate the stability evolution of soft and hard interbedded bedding reservoir slopes considering the spatial variation and temporal deterioration of shear strength parameters of rock masses and bedding planes.In the modified LEM,the S-curve model is used to define the spatial variation of shear strength parameters,and general deterioration equations of shear strength parameters with the increasing number of wettingdrying cycles(WDC)are proposed to describe the temporal deterioration.Also,this method is applied to evaluate the stability evolution of a soft and hard interbedded bedding reservoir slope,located at the Three Gorges Reservoir.The results show that neglecting the spatial variation and temporal deterioration of shear strength parameters may overestimate slope stability.Finally,the modified LEM provides useful guidance to reasonably evaluate the long-term stability of soft and hard interbedded bedding reservoir slopes in reservoir area.
基金supported by the National Key Research and Development Program of China(Nos.2022YFC2903902 and 2022YFC2903903)the National Natural Science Foundation of China(Nos.U1903216 and 52174070).
文摘The significant difference between the mechanical properties of soft rock and hard rock results in the complexity of the failure mode of the anti-dip layered slope with soft and hard rock interbedding.In order to reveal the landslide mechanism,taking the north slope of Fushun West Open-pit Mine as an example,this paper analyzed the failure mechanism of different landslides with monitoring and field surveys,and simulated the evolution of landslides.The study indicated that when the green mudstone(hard rock)of the anti-dip slope contains siltized intercalations(soft rock),the existence of weak layers not only aggravates the toppling deformation of anti-dip layered slope with high dip,but also causes the shear failure of anti-dip layered slope with stable low dip.The shear failure including subsidence induced sliding and wedge failure mainly exists in the unloading zone of the slope.Its failure depth and failure time were far less than that of toppling failure.In terms of the development characteristics of deformation,toppling deformation has the long-term and progressive characteristics,but shear failure deformation has the abrupt and transient characteristics.This study has deepened the understanding of such slope landslide mechanism,and can provide reference for similar engineering.
