循环加卸载下岩石力学性能的加载速率效应研究

Study on Loading Rate Effect of Rock Mechanical Properties Under Cyclic Loading and Unloading

矿山开采过程中存在岩石受周期性扰动影响,对岩石的力学性质产生显著影响。为了解不同循环加卸载方式下岩石的加载速率效应,对矽卡岩试样进行不同加载速率的恒下限循环加卸载和变下限循环加卸载试验,对比分析了不同加载速率两种循环加卸载方式下试样的变形特征、能量演化规律以及破坏特性。结果表明:试样的峰值强度和残余变形具有不同加速率效应,但其峰值强度相比于常规单轴压缩试验均有提升;随加载速率增大,试样各阶段的输入能、弹性能和耗散能均呈增长趋势,但表现形式有所差异;试样的破坏方式及形态均表现出加速率效应,随着加载速率的增大其破坏程度加剧。

In the process of mining,there are rocks affected by cyclic disturbances,which have significant effects on the mechanical properties of rocks.To understand the loading rate effect of rocks under different cyclic loading and unloading methods,this paper carries out constant lower limit cyclic loading and unloading,variable lower limit cyclic loading and unloading tests on sillimanite specimens with different loading rates,comparatively analyzes the deformation characteristics,the energy evolution law and the destructive characteristics of the specimens under the two cyclic loading and unloading methods with different loading rates.The test results show that the peak strength and residual deformation of the specimen have different acceleration rate effects,but the peak strength is improved compared with the conventional uniaxial compression test;with the increase of the loading rate,the input energy,elastic energy and dissipation energy of the specimen in all stages show an increasing trend,but with some differences in the form of manifestation;the destruction of the specimen and its morphology show the acceleration rate effect,and the degree of destruction is intensified with the increase of the loading rate.