基于弹塑性损伤模型的岩石加卸载计算研究

基于经典弹塑性理论,引入损伤因子,综合考虑岩石在外力作用下的塑性变形与损伤演化,提出一种各向同性弹塑性损伤耦合模型。根据以上理论编制有限元计算程序,较好地描述了岩石在不同加卸载路径中的应力-应变特性。通过程序模拟计算,具体结论如下:在常规路径加载中,岩石的峰值强度与残余强度均随围压的增加而增加。在卸围压路径下,残余应力受初始围压影响较小,但侧向应变与体应变有着明显的增加。轴向荷载的提高使岩石损伤值增加,卸围压过程中最大损伤因子均大于同等初始围压下的常规路径试验。

Computing Research on Rock Loading and Unloading Based on Coupled Elastoplasticity Damage Model

Based on classical elastoplasticity theory and by introducing the scalar damage factor, a coupled isotropic elastoplasticity damage model is proposed for the rock in different loading and unloading condition. In the proposed model, the damage evolution and plastic strain are synthetically considered. Then, the proposed model has been programmed and certain numerical simulations have been done. The numerical simulations show that the proposed model can better describes the stress-strain characteristics of rock under different stress path. Some conclusions are as follows: in conventional triaxial tests, the peak strength and residual strength of rock will both increase as the confining pressure increase. Under the unloading path, the initial confining pressure has little effect on the residual stress, but the lateral strain and volumetric strain increase obviously. The increase of axial loading lead to the increase of damage factor and in the process of unloading path, the maximum damage factor is larger than that of the conventional path under the same initial confining pressures.