Numerical analysis of the mechanical properties of rock materials under tiered and multi-level cyclic load regimes
Numerical analysis of the mechanical properties of rock materials under tiered and multi-level cyclic load regimes
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分层多级循环荷载条件下岩石材料力学性能的数值分析
DOI：
10.1016/j.soildyn.2020.106186
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发表时间：
2020
影响因子：
4
通讯作者：
Fu Xiaodong
中科院分区：
文献类型：
--
作者：
Zhou Yongqiang;Sheng Qian;Li Nana;Fu Xiaodong
在工程实践中，岩石承受循环荷载的现象十分普遍。岩石材料在分层、单级和多级循环荷载状态下的力学性能（即，在不同频率、最小应力和振幅下）进行了数值模拟。从应力-应变曲线、模量、损伤、强度等方面对两种荷载进行了比较。结果表明，该模型能有效地反映岩石材料在不同循环荷载作用下的力学特性。在分层和多级循环荷载作用下，滞回线的面积和宽度随外加应力的增大而增大，但应力-应变曲线的斜率、滞回线的面积和宽度、最大应变和不可逆变形在不同荷载下有所不同。加载变形模量随外加应力的增大而减小，且在分层、单级和多级循环加载下，其减小幅度不同。随着加载应力的增大，岩石试件在分层循环荷载作用下的损伤演化呈现出近似倒“S”形的增大趋势。在多级循环荷载作用下，损伤变量在第一级迅速增加，然后相对稳定，并随着外加应力的增加而缓慢增加。此外，不同加载方式下岩石的峰值强度不同，表明循环加载对岩石强度既有强化作用，又有损伤作用。
In engineering practice, it is a common that rocks are subjected to cyclic loading. The mechanical properties of rock materials under tiered, single-level, and multi-level cyclic load regimes (i.e., with different frequency, minimum stress, and amplitude) were numerically investigated by using a dynamic constitutive model for rock materials. A comparison between these loads from the aspects of stress-strain curve, modulus, damage, and strength was undertaken. The results indicate that the model can effectively reflect the different mechanical properties of rock materials under different cyclic load regimes. Under the action of tiered and multi-level cyclic loading, the area and width of the hysteresis loops become larger with increasing applied stress, but the slope of stress-strain curve, area and width of the hysteresis loops, maximum strain, and the irreversible deformation vary under different loads. The loading deformation modulus decreases with the increase of applied stress and the reductions therein are different when subjected to tiered, single-level, and multi-level cyclic loading. With increasing applied stress, the damage evolution in rock specimens subjected to tiered cyclic loading present an increasing trend and the trend likes an approximately inverted “s” -shape. Under multi-level cyclic loading, the damage variables increase rapidly at the first level, then become relatively stable and increase slowly as the applied stress increases. Furthermore, the peak strength of rock differs under different load regimes, and results indicate that cyclic loading has both strengthening and damaging effects on rock strength.