循环剪切荷载作用下岩石节理强度劣化规律试验模拟研究

EXPERIMENT SIMULATION STUDY OF STRENGTH DEGRADATION OF ROCK JOINTS UNDER CYCLIC SHEAR LOADING

采用水泥砂浆为相似材料,制备5种起伏角度、3种岩壁强度的锯齿型节理试样。利用自行研制的节理循环剪切试验机,对制备的节理试样进行4种法向应力下的循环剪切试验。根据循环剪切试验过程和试验曲线,分析单个剪切循环中应力-位移曲线的峰值强度特点,以τfn来表示节理在第n个剪切循环中的峰值剪切强度;并进一步定义Rτ=τfn/τf1为剪切强度比,来表征节理在循环剪切荷载作用下经历一定剪切循环后峰值强度的劣化程度。基于多种条件下的节理循环剪切试验结果和定义的指标,分析峰值剪切强度τfn随循环剪切周期N的变化规律;并通过对比不同工况的试验结果,分析起伏角度、法向应力、岩壁强度对循环剪切荷载作用下节理强度劣化规律的影响。

Using cement mortar as similar material,joint specimens with three joint wall strengths and five asperity angles were prepared.Then a series of cyclic shear tests are performed at four normal stresses on the cyclic shear test apparatus.Tests results show that,shear stress-shear displacement curve has peak strength of each shear cycle,and the shear strength of joints gradually decrease with the cyclic number increase.The peak shear strength of joint after n cycles is expressed as,then the = / is defined as shear strength ratio,so as to characterize the degree of strength deterioration under cyclic shear loads.Based on a variety of cyclic shear test results and,the relationships between peak shear strength of joints and shear cycles are analyzed.By comparing the results under different experimental conditions,the effects of asperity angles,joint wall strength and normal stress on the joint mechanical properties are also analyzed.