Hydromechanical coupling tests for mechanical andpermeability characteristics of fractured limestone in completestress-strain process
Hydromechanical coupling tests for mechanical andpermeability characteristics of fractured limestone in completestress-strain process
复制标题
全应力-应变过程中裂隙灰岩力学与渗透特性的水力耦合试验
DOI：
10.1007/s12665-016-6322-x
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发表时间：
2017
影响因子：
2.8
通讯作者：
Yu Chen
中科院分区：
文献类型：
--
作者：
Yanlin Zhao;Jingzhou Tang;Yu Chen
为阐明裂隙灰岩在全应力-应变过程中的力学和渗透特性，进行了不同水压差和围压条件下的流力耦合试验。石灰岩破裂试件的力学特性对围压、水压差和有效应力非常敏感。由于有效最小主应力的降低，裂隙灰岩的侧向变形被激活，从而削弱了岩石的强度和变形模数。实验结果验证了考虑有效应力效应的莫尔-库仑屈服准则在流固耦合条件下的有效性。渗透率值在整个应力应变过程中呈现出减小-逐渐增加-快速增加-小幅下降四个阶段，大致分别对应于体积压缩阶段、弹性变形阶段、屈服阶段、峰后阶段和残余强度阶段。在2-5兆帕的低差水压力下，上述对应关系明显。但在8~14 Mpa的高水压差下，渗透率降低阶段比体积压缩阶段短，与上述对应关系有偏差。在体积压缩阶段，渗透率与体积应变之间的关系用三次多项式描述。然而，在扩容阶段，渗透率与体积应变之间的关系很难用统一的拟合方程来描述。
To clarify mechanical and permeability characteristics of fractured limestone in complete stress–strain process, the hydromechanical coupling tests with various differential water pressures and confining pressures were performed. The mechanical characteristics of fractured limestone specimens are sensitive to confining pressure, differential water pressure, and effective stress. The increasing differential water pressure weakens the rock strength and deformation modulus by activating the lateral deformation of fractured limestone, which is attributed to the decrease in the effective minimum principal stress. The experimental results verify the validity of Mohr–Coulomb yield criterion considering the effective stress effect under hydromechanical coupling condition. 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, yield, and post-peak stage, as well as residual strength stage, respectively. At a low differential water pressure in the range of 2–5 MPa, the corresponding relationship mentioned above is obvious. However, at high differential water pressures up to 8–14 MPa, there is a deviation from the correspondence above, i.e., permeability reduction stage is shorter than the stage of volumetric compression. A cubic polynomial is used to describe the relationship between permeability and volumetric strain at volumetric compression stage. However, it is difficult to describe the relationship between the permeability and volumetric strain by a uniform fitting equation at the dilatancy stage.