【摘要】 为研究裂隙灰岩在全应力–应变过程中的力学特性和渗透性特点,对裂隙灰岩进行不同渗透压和围压组合下的水–力耦合试验,研究水–力耦合作用下裂隙灰岩的强度和变形特性,并定义全应力–应变过程中6个关键的渗透率值。试验结果表明:渗透压对裂隙灰岩的力学特性有较大影响,渗透压的存在降低了裂隙灰岩的强度和变形模量,加剧其侧向变形,水–力耦合作用下裂隙灰岩的强度特性可用莫尔–库仑屈服准则来表征;全应力–应变过程中,裂隙灰岩渗透率经历缓慢下降–缓慢增加–快速增长–小幅度下降4个阶段,这大致对应于全应力–应变过程中体积压缩阶段,近线性变形阶段,峰值点附近的破裂阶段和峰后残余强度阶段。在较低渗透压(2 MPa左右)下,上述相应关系吻合情况良好,而在较高渗透压(8 MPa以上)下,上述相应吻合关系存在偏差,渗透率下降阶段要短于体积压缩阶段;在较低渗透压(2 MPa左右)下体积压缩阶段的渗透率与体积应变之间的关系可用负指数函数来描述,而在较高渗透压(8 MPa以上)作用下,在体积压缩阶段的渗透率和体积应变之间的关系可用三次多项式来描述。更多还原

【Abstract】 To clarify mechanical and permeability characteristics of fractured limestone in complete stress-strain process,the hydro-mechanical coupling tests on fractured limestone at various seepage pressures and confining pressures were performed,and the strength and deformation characteristics of fractured limestone under the hydro-mechanical coupling were studied. The six key permeability values in complete stress-strain process were defined. The results showed that the mechanical characteristics of fractured limestone are sensitive to seepage pressure,which reduces rock strength and deformation modulus,activating the lateral deformation of fractured limestone. The strength characteristics of fractured limestone can be characterized by the Mohr-Coulomb yield criterion under the hydro-mechanical coupling;The permeability values display four stages of decrease-gradual increase-rapid increase-small drop in complete stress-strain process,which roughly correspond to volumetric compression stage,elastic deformation stage,failure stage near peak strength point and residual strength,respectively. At low seepage pressure(about 2 MPa),the correspondence above is perfect. However,at high seepage pressure(above 8 MPa),there is a deviation from the correspondence above,i.e. permeability reduction stage is shorter than the stage of volumetric compression. A negative exponential equation can describe the relationship between permeability and volumetric strain in volumetric compression stage at low seepage pressure(about 2 MPa). At high seepage pressure(above 8 MPa),a cubic polynomial can be used to describe the relationship between permeability and volumetric strain in volumetric compression stage.更多还原