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为了研究准静态加载条件下岩石试件巴西劈裂裂纹扩展规律,采用MTS试验机进行准静态加载,同时用高速摄像机记录裂纹扩展过程。采用白光数字散斑处理软件对摄像机记录的照片进行处理,得到试件裂纹扩展过程中应变场的演化情况。通过实验和分析可以看出,由于端部效应及加载方式的原因,因此裂纹起裂点在底部加载部位;泥岩试件表面裂纹的平均扩展速度为252m/s;岩石的非均质性即内部微缺陷、微裂纹使得泥岩试样的开裂并不是沿着中心直径方向,而是偏离一定的角度,初始偏离角度约为17°。裂纹扩展过程可以划分为三个阶段:泥岩试件宏观变形阶段(宏观无裂纹)、宏观裂纹稳定扩展阶段、宏观裂纹动态张裂阶段。同时,在裂纹扩展过程中,表面第一主应变场、水平位移场等变化明显,在开裂部位第一主应变最大。通过对圆盘泥岩试件裂纹扩展实验研究,可为研究岩石破裂及其演化规律提供依据。
In order to study the crack propagation law of Brazilian specimens under quasi-static loading conditions, MTS testing machine was used for quasi-static loading and high-speed camera was used to record the crack propagation process. The photos recorded by the camera were processed by white digital speckle processing software to get the evolution of the strain field during crack propagation. Through the experiment and analysis, it can be seen that due to the end effect and the loading method, the cracking initiation point is at the bottom loading point. The average surface crack propagation rate of mudstone specimen is 252m / s. The heterogeneity of rock The micro-cracks and micro-cracks make the cracking of the mudstone sample not along the center diameter, but deviate from a certain angle, and the initial deviation angle is about 17 °. The crack propagation process can be divided into three stages: the macroscopic deformation stage (macroscopically no crack) of mudstone specimen, the stable expansion stage of macroscopic crack and the dynamic cracking stage of macroscopic crack. At the same time, during the crack propagation, the first main strain field and horizontal displacement field have obvious changes, and the first main strain is the largest in the cracked area. Experimental study on the crack propagation of disk mudstone can provide the basis for the study of rock failure and its evolution.