单轴压缩作用下内置裂隙扩展的CT扫描试验

精选出一种与岩石较为接近的相似材料制作标准试件,并在其内部预置单币状裂隙,进行加载过程中的CT实时扫描试验。通过分析CT扫描图像,初步判定试件的破坏是由裂隙的损伤演化造成的。采用多种区域划分的方法,通过CT数及CT方差的对比分析,获得随载荷的不断增加裂隙被压密、自相似扩展、翼裂纹扩展、微裂纹扩展、裂纹汇合贯通以及裂纹加速扩展、试件崩裂的损伤演化过程;同时,也得到初裂强度、翼裂纹扩展长度和自相似扩展长度等一些重要参数;将试件破坏前的应力、应变过程曲线分为4段,说明预置裂隙的损伤演化过程。

CT REAL-TIME SCANNING TESTS ON ROCK SPECIMENS WITH ARTIFICIAL INITIAL CRACK UNDER UNIAXIAL CONDITIONS

The crack propagation mechanism of the rock-like material that is carefully selected through comparison of similar physico-mechanical parameters is studied.The CT real-time scanning tests of the rock specimens with artificial single initial disk-like fracture are carried out to study the propagation mechanism of the 3D crack under compression stresses.From CT image analysis,it is preliminarily determined that the failure of the specimens is caused by the damage evolution of the crack.From the comparative analysis of CT values and CT variances in manifold areas,some valuable information and important parameters are obtained with increasing load as follows:(1)the courses of compressed crack;(2)self-similar propagation;(3)wings growth;(4)micro-cracks propagation;(5)cracks joining;(6)cracks accelerated growth;(7)damage evolution course of the specimen failure and the parameters of initial propagation strength;(8)propagation length of wing crack;and(9)self-similar propagation length of crack,etc..The stress-strain curve is divided into four sections before failure of the specimen,and damage propagation mechanisms of initial fracture is given.