基于近场动力学的岩石不同应力路径损伤演化

加卸载效应普遍存在于各类岩土工程中，为研究岩体在不同应力路径下加卸载的力学响应和损伤演化规律，通过在传统键型近场动力学本构模型中引入键的损伤变量函数，以反映岩石材料应力应变曲线中先应变硬化再应变软化的非线性阶段，采用改进键型近场动力学模型数值模拟与室内细砂岩加卸载试验对照的方法研究了细砂岩在不同加卸载路径下的力学、损伤演化规律。结果表明：改进的键型近场动力学本构模型能够较好地模拟岩石材料先应变硬化再应变软化力学性质和在不同应力路径下的力学响应及损伤发展趋势；在常规三轴路径下，岩石的抗压强度与围压呈较严格的正相关变化；定义的损伤值可直观的对比出不同加卸载路径与常规三轴压缩下岩石的损伤发展情况，相对常规三轴压缩，卸荷路径加快了岩石材料的破坏，且升轴压破坏程度>恒轴压破坏程度>卸轴压破坏程度。

Damage Evolution of Rocks under Different Stress Paths based on Peridynamics

Loading and unloading effects are common in all kinds of geotechnical engineering. In order to study the mechanical response and damage evolution law of rock mass loading and unloading under different stress paths, the damage variable functionof the bond is introduced into the traditional bond-based peridynamics constitutive model to reflect the nonlinear stage of strain hardening and then strain softening in the stress-strain curve of rock materials. The mechanics and damage evolution of fine sandstone under different loading and unloading paths were studied by using the improved bond-based peridynamics model and the laboratory loading and unloading test. The results show that the improved bond-based peridynamics constitutive model can simulate the mechanical properties of strain hardening and then strain softening of rock materials and the mechanical response and damage development trend under different stress paths. Under the conventional triaxial path, the compressive strength and confining pressure of rock show a strict positive correlation. The defined damagevalue can intuitively compare the damage development of rock under different loading and unloading paths and conventional triaxial compression. Compared with conventional triaxial compression, the unloading path speeds up the failure of rock materials, and the damage degree of ascending axial pressure > constant axial pressure > unloading axial pressure.