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富含孔隙/裂隙岩体的非线性变形对于工程的安全评价具有重要意义。在多物理场耦合分析求解器TOUGH-FLAC3D中实现双应变胡克模型(two-part Hooke s model,简称TPHM)的数值解法,并界定TPHM的适用条件。TPHM假设:对于岩体中可承受较大变形的软体(如孔隙、裂隙等),用基于自然应变(或真应变,即岩体变形与当前应力状态下的岩体体积之比)的胡克定律来描述;而对于只承受较小变形的硬体部分用基于工程应变(岩体变形与原始应力状态下的岩体体积之比)的胡克定律来描述。通过对室内岩样的应力-应变特征计算分析,表明TPHM在本质上反映了加卸载过程中低应力阶段的非线性变形行为,该力学响应完全取决于孔隙/裂隙的自然应变(真应变);通过对瑞士Mont Terri岩石实验室的深部ED-B巷道围岩的变形场计算分析,显示出TPHM较为准确地反映了开挖卸载诱发的围岩变形特征。因为TPHM本质上是考虑了低应力状态下孔隙/裂隙对岩石力学性质的影响,因此,在具有卸荷扰动特征的岩石工程中应用TPHM模型进行设计分析更符合实际。
The nonlinear deformation of the pore-rich / fractured rock mass is of great significance to the safety evaluation of the project. The numerical solution of the two-part Hooke’s model (TPHM) is implemented in TOUGH-FLAC3D, a multi-physics coupled analytical solver, and the applicable conditions of TPHM are defined. TPHM assumes that for a soft body (such as voids, fractures, etc.) that can withstand large deformations in a rock mass, Hooks are based on natural strain (or true strain, ie, the ratio of rock mass deformation to rock mass volume at the current stress state) Law; and for the part of the hardware that is subject to the smaller deformations, it is described by Hooke’s law based on the engineering strain (the ratio of rock mass deformation to the mass of rock under the initial stress). The analysis of stress - strain characteristics of indoor rock samples shows that TPHM essentially reflects the nonlinear deformation behavior during low stress phase during loading and unloading. The mechanical response depends entirely on the natural strain (true strain) of pores / fractures. Computation and analysis of the deformation field of the surrounding rock mass of ED-B roadway in the Mont Terri rock laboratory in Switzerland show that the TPHM accurately reflects the surrounding rock deformation characteristics induced by excavation unloading. Because TPHM essentially considers the influence of porosity / fissures on rock mechanics properties under low-stress conditions, it is more realistic to apply TPHM model to rock engineering with unloading disturbances.