作者：荣笛¹, 孟陆波²

作者单位：1. 成都理工大学环境与土木工程学院，四川 成都 610059;
2. 成都理工大学 地质灾害防治与地质环境保护国家重点实验室，四川 成都 610059

关键词：岩石力学;滞回环;循环荷载;围压

摘要：

为进一步探究岩石在高应力条件下循环加载的滞后现象，取某深基坑工程含水岩层中的板岩制成饱和岩样，运用MTS815试验机进行三轴循环加卸载试验，研究其不同围压下的滞后特性。试验结果表明，在卸载转变为加载的过程中产生应变差，但这并不完全由能量损耗引起，主要原因是弹性因素。此过程中岩样与垫块发生碰撞产生与加载方向相同的反弹力，岩样在反弹力与荷载的共同作用下发生变形，由于垫块可视为刚体，岩样吸收反弹力能量产生额外变形，导致加载时应变相位超前于应力相位，由此判断在应力下限值附近滞回曲线不为严格的尖点，并提出计算动弹性模量的修改公式。围压的增加使应力应变相位差变小，也使动弹性模量修改公式与传统公式计算结果更接近，可认为围压的增加会降低岩样的滞后性。

Study on hysteresis characteristics of saturated slate under triaxial cyclic load
RONG Di¹, MENG Lubo²
1. School of Environment and Civil Engineering, Chengdu University of Technology, Chengdu 610059, China;
2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
Abstract: In order to further study the hysteresis of the rocks in the cyclic loading phase under high stress, some slates shall be taken from the water-bearing rock stratum of a deep foundation pit to prepare a saturated rock sample, then the triaxial cyclic loading/unloading experiments shall be carried out with MTS815 testers to study the hysteresis of rock sample under different confining pressures. The test result shows that there was some strain difference occurred during the process from unloading to loading, however, this was not solely caused by energy loss, the elastic factors were still believed to be the major reasons. During this process, the collision between the rock sample and the cushion block produced the same rebound force as the loading direction, the rock sample deformed under the combined action of rebound force and load, as the cushion block could be considered a rigid body, the rock sample absorbed the rebound force energy then generated additional deformation, resulting in the strain phase leads the stress phase during loading, from which the hysteresis curve near the lower limit of stress could be considered not a strict sharp point, then a modified formula was proposed for calculating dynamic elastic modulus. The increase in confining pressure reduces the phase difference between stress and strain, it also makes the modified formula of dynamic elastic modulus closer to the calculation result of the traditional formula, it could be considered that the increase of confining pressure reduces the hysteresis of the rock sample.
Keywords: rock mechanics;hysteresis loop;cyclic load;confining pressure
2021, 47(6):57-62  收稿日期: 2020-11-10;收到修改稿日期: 2020-12-02
基金项目: 四川省科技计划项目(2019YJ0538)
作者简介: 荣笛(1994-),男,四川成都市人,硕士研究生,专业方向为土工试验与岩土工程
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