The geometric properties of fracture surfaces significantly influence shear-seepage in rock fractures,introducing complexities to fracture modelling.The present study focuses on the hydro-mechanical behaviours of roug...The geometric properties of fracture surfaces significantly influence shear-seepage in rock fractures,introducing complexities to fracture modelling.The present study focuses on the hydro-mechanical behaviours of rough rock fractures during shear-seepage processes to reveal how dilatancy and fracture asperities affect these phenomena.To achieve this,an improved shear-flow model(SFM)is proposed with the incorporation of dilatancy effect and asperities.In particular,shear dilatancy is accounted for in both the elastic and plastic stages,in contrast to some existing models that only consider it in the elastic stage.Depending on the computation approaches for the peak dilatancy angle,three different versions of the SFM are derived based on Mohr-Coulomb,joint roughness coefficient-joint compressive strength(JRC-JCS),and Grasselli’s theories.Notably,this is a new attempt that utilizes Grasselli’s model in shearseepage analysis.An advanced parameter optimization method is introduced to accurately determine model parameters,addressing the issue of local optima inherent in some conventional methods.Then,model performance is evaluated against existing experimental results.The findings demonstrate that the SFM effectively reproduces the shear-seepage characteristics of rock fracture across a wide range of stress levels.Further sensitivity analysis reveals how dilatancy and asperity affect hydraulic properties.The relation between hydro-mechanical properties(dilatancy displacement and hydraulic conductivity)and asperity parameters is analysed.Several profound understandings of the shear-seepage process are obtained by exploring the phenomenon under various conditions.展开更多
Understanding the mechanical and hydraulic properties of fractured rocks and their coupled processes is of great significance for the exploration,design,construction,operation,and maintenance of many rock engineering ...Understanding the mechanical and hydraulic properties of fractured rocks and their coupled processes is of great significance for the exploration,design,construction,operation,and maintenance of many rock engineering projects such as hydropower development,oil and gas extraction,and underground waste disposal.With the rapid advancement of global and national strategies such as the“Paris Agreement”and the“Belt and Road Initiative”,more and more projects are developed in the complex geological environment with varying geological structures.Shear failure and rock instability are prone to occur in fractured rock masses under the coupled effects of high stress,high pore pressure,and engineering disturbance,which are main sources for engineering disasters such as roof collapse and caving,water and mud inrushes,and induced earthquakes.To solve these problems,extensive research on the coupled shear-flow behavior of fractures has been conducted.However,due to the complex mechanical,hydraulic and geometrical characteristics of single fractures and fracture networks,a large number of outstanding issues related to the impact of the coupled processes on the engineering characteristics of rock masses are still unsolved.The relevant experimental apparatuses and methods remain to be further developed.Therefore,in this review,we analyze and summarize the existing shear-flow experimental apparatuses,classify apparatus configurations,specimen shapes,and testing principles,and compare their advantages and disadvantages.We also summarize the main scientific findings obtained from various experimental apparatuses,aiming to provide a reference for developing new shear-flow experimental apparatuses and conducting related scientific research in the future.展开更多
饱和粉土在地震作用下会发生液化变形,从而导致建立在其上的建(构)筑物发生破坏。工程场地区域内粉土单元通常存在初始剪应力作用,为探究初始剪应力对饱和粉土液化特性的影响,将液化后粉土视为流体进行了一系列循环扭剪试验研究。试验...饱和粉土在地震作用下会发生液化变形,从而导致建立在其上的建(构)筑物发生破坏。工程场地区域内粉土单元通常存在初始剪应力作用,为探究初始剪应力对饱和粉土液化特性的影响,将液化后粉土视为流体进行了一系列循环扭剪试验研究。试验结果表明,初始剪应力对饱和粉土剪应力-剪应变率曲线影响显著,随着初始剪应力τ_(s)的增大,剪应力-剪应变率曲线由“椭圆形”向“哑铃形”过渡逐渐转变为由“镰刀形”向“椭圆形”至“锤形”过渡;表观黏度η与振次N的衰减曲线随着τ_(s)的增大先降低再抬升,平均流动系数κ与振次N的增长曲线发展速度随着τ_(s)的增大先加快后减慢,固液相变孔压比r_(uth)随着τ_(s)的增大先减小后增大,当τ_(s)=5 k Pa时饱和粉土的r_(uth)最小。展开更多
基金support from the National Natural Science Foundation of China(Grant Nos.51991392 and 42293355).
文摘The geometric properties of fracture surfaces significantly influence shear-seepage in rock fractures,introducing complexities to fracture modelling.The present study focuses on the hydro-mechanical behaviours of rough rock fractures during shear-seepage processes to reveal how dilatancy and fracture asperities affect these phenomena.To achieve this,an improved shear-flow model(SFM)is proposed with the incorporation of dilatancy effect and asperities.In particular,shear dilatancy is accounted for in both the elastic and plastic stages,in contrast to some existing models that only consider it in the elastic stage.Depending on the computation approaches for the peak dilatancy angle,three different versions of the SFM are derived based on Mohr-Coulomb,joint roughness coefficient-joint compressive strength(JRC-JCS),and Grasselli’s theories.Notably,this is a new attempt that utilizes Grasselli’s model in shearseepage analysis.An advanced parameter optimization method is introduced to accurately determine model parameters,addressing the issue of local optima inherent in some conventional methods.Then,model performance is evaluated against existing experimental results.The findings demonstrate that the SFM effectively reproduces the shear-seepage characteristics of rock fracture across a wide range of stress levels.Further sensitivity analysis reveals how dilatancy and asperity affect hydraulic properties.The relation between hydro-mechanical properties(dilatancy displacement and hydraulic conductivity)and asperity parameters is analysed.Several profound understandings of the shear-seepage process are obtained by exploring the phenomenon under various conditions.
基金funded by the National Natural Science Foundation of China(Grant Nos.42077252,42011530122)Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QE069).
文摘Understanding the mechanical and hydraulic properties of fractured rocks and their coupled processes is of great significance for the exploration,design,construction,operation,and maintenance of many rock engineering projects such as hydropower development,oil and gas extraction,and underground waste disposal.With the rapid advancement of global and national strategies such as the“Paris Agreement”and the“Belt and Road Initiative”,more and more projects are developed in the complex geological environment with varying geological structures.Shear failure and rock instability are prone to occur in fractured rock masses under the coupled effects of high stress,high pore pressure,and engineering disturbance,which are main sources for engineering disasters such as roof collapse and caving,water and mud inrushes,and induced earthquakes.To solve these problems,extensive research on the coupled shear-flow behavior of fractures has been conducted.However,due to the complex mechanical,hydraulic and geometrical characteristics of single fractures and fracture networks,a large number of outstanding issues related to the impact of the coupled processes on the engineering characteristics of rock masses are still unsolved.The relevant experimental apparatuses and methods remain to be further developed.Therefore,in this review,we analyze and summarize the existing shear-flow experimental apparatuses,classify apparatus configurations,specimen shapes,and testing principles,and compare their advantages and disadvantages.We also summarize the main scientific findings obtained from various experimental apparatuses,aiming to provide a reference for developing new shear-flow experimental apparatuses and conducting related scientific research in the future.
文摘饱和粉土在地震作用下会发生液化变形,从而导致建立在其上的建(构)筑物发生破坏。工程场地区域内粉土单元通常存在初始剪应力作用,为探究初始剪应力对饱和粉土液化特性的影响,将液化后粉土视为流体进行了一系列循环扭剪试验研究。试验结果表明,初始剪应力对饱和粉土剪应力-剪应变率曲线影响显著,随着初始剪应力τ_(s)的增大,剪应力-剪应变率曲线由“椭圆形”向“哑铃形”过渡逐渐转变为由“镰刀形”向“椭圆形”至“锤形”过渡;表观黏度η与振次N的衰减曲线随着τ_(s)的增大先降低再抬升,平均流动系数κ与振次N的增长曲线发展速度随着τ_(s)的增大先加快后减慢,固液相变孔压比r_(uth)随着τ_(s)的增大先减小后增大,当τ_(s)=5 k Pa时饱和粉土的r_(uth)最小。
