循环剪切荷载作用下充填物对结构面剪切特性影响试验研究

Influence of filling material on the behavior of joints under cyclic shear loading

利用相似材料复制劈裂结构面,进行常法向应力下循环剪切试验,研究无充填、充填黄泥3mm、充填石膏3mm和充填岩屑3 mm条件下结构面循环剪切强度、变形和形貌演化特性。结果表明:(1)循环剪切中占主导地位的破坏模式会发生改变,无充填时由剪断破坏向磨损破坏转化,充填黄泥时主要为滑移破坏,充填石膏时由剪断破坏向滑移破坏再向磨损破坏转化,充填岩屑时由剪断破坏向磨损破坏转化。(2)随着循环剪切次数增加,无充填和充填黄泥时峰值剪应力以减速率减小,充填石膏和岩屑时峰值剪应力先减小再以减速率增大,充填物会弱化结构面循环剪切强度,其中以黄泥的弱化影响最大。(3)不同充填材料条件下,结构面循环剪切中平均剪胀角均以减速率减小,有充填时循环剪切中剪缩现象更明显,其中充填黄泥时剪缩幅度最小,充填石膏时剪缩幅度最大。(4)有充填物条件下,循环剪切后结构面磨损程度比无充填条件下要小,其中以充填黄泥时磨损程度最小,充填石膏时磨损程度相对最大。

In this study, cyclic shear test were conducted on the crusted structural surface replicated with similar material under normal stress. The shear strength, deformation and morphology evolution characteristics of joints under cyclic shearing were studied without filling, with 3 mm yellow mud infilling, 3 mm plaster infilling and 3 mm detritus infilling, respectively. It was found that the failure mode of joints developed under cyclic shearing. Joints without filling changed from shear failure to wear-out failure, while joints with yellow mud mainly showed slip failure. Joints with plaster changed from shear failure to slip failure and then to wear-out failure, while joints with detritus changed from shear failure to wear-out failure. With the increase of cyclic shear times, the peak shear stress of joints without filling and with yellow mud infilling decreased in deceleration rate, while those with plaster and detritus infilling decreased firstly and then increased in deceleration rate. These results indicate that filling material can weaken the shear strength of joints under cyclic shearing, especially for those with yellow mud filling. Under different filling conditions, the average dilation angles all reduce in deceleration rate under cyclic shearing. The shearing shrinkage is more obvious in filled joints, in which the shearing shrinkage is the smallest with yellow mud infilling and the largest with plaster infilling. The wear degree of filled joints after cyclic shear is lighter than that of unfilled joints, while the wear degree is the smallest when filling yellow mud, the wear degree is relatively biggest when filling plaster.