论文部分内容阅读
开展3种不同应力路径下的花岗岩三轴加卸载试验,得到花岗岩在不同加卸载路径下的应力–应变曲线,分析其破坏特征、变形特征及其强度特征。试验结果表明:(1)卸围压过程中岩石环向应变和体积应变与围压在初始阶段呈线性关系,而后呈明显的非线性关系,岩石轴向变形不明显,变形主要表现为环向变形,岩石扩容显著,脆性破坏特征明显。(2)卸荷试验中岩石变形模量随卸荷比的增大而减小,而泊松比随卸荷比的增大而增大,在卸荷初期岩石变形参数劣化不明显,而后呈指数型变化,且岩石加轴压卸围压试验较恒轴压卸围压试验对变形参数的影响更加明显。(3)在高应力卸荷条件下,Mogi-Coulomb强度准则较Mohr-Coulomb强度准则更能反映岩石的卸荷破坏强度特征;相对于常规三轴压缩试验,恒轴压卸围压试验试样黏聚力c降低24.21%,内摩擦角?增大16.71%,而加轴压卸围压试验试样黏聚力c增大10.25%,内摩擦角?减少6.64%,表明在恒轴压卸围压试验中试样抗破坏的主控因素为摩擦力,而在加轴压卸围压试验中为黏聚力。
Uniaxial loading and unloading tests of granite under three different stress paths are carried out. The stress-strain curves of granite under different loading and unloading paths are obtained, and the failure characteristics, deformation characteristics and strength characteristics of the granite are analyzed. The results show that: (1) There is a linear relationship between the circumferential strain and the volumetric strain in the unloading confining pressure and the confining pressure in the initial stage, and then the nonlinear relationship is obvious. The rock axial deformation is not obvious, and the deformation is mainly in the circumferential direction Deformation, significant rock expansion, brittle failure obvious characteristics. (2) In the unloading test, the rock deformation modulus decreases with the increase of the unloading ratio, while the Poisson’s ratio increases with the increase of the unloading ratio. The deformation parameters of the rock are not obviously deteriorated at the initial unloading time, Exponential changes, and the rock plus axial compression unloading pressure test than the constant pressure unloading confining pressure test on the deformation parameters of the more obvious. (3) Mogi-Coulomb strength criterion can better reflect the characteristics of rock unloading failure strength than Mohr-Coulomb strength criterion under high stress and unloading conditions. Comparing with conventional triaxial compression test, Cohesion c decreased by 24.21%, the internal friction angle increased by 16.71%, while the addition of axial compression and unloading confining test specimen cohesion c increased by 10.25%, the internal friction angle decreased by 6.64%, indicating that the constant pressure in the unloading In the confining pressure test, the main factor of anti-sabotage of the sample is the friction force, but it is the cohesion force in the confining pressure test of plus shaft pressure.