基于声发射技术的含初始缺陷混凝土破坏分析

初始缺陷对混凝土的变形和破坏特性有着重要的影响。本文对含有不同尺寸、不同倾斜角度初始缺陷的混凝土试件进行单轴压缩试验，并基于声发射技术分析混凝土的变形和破坏特性。试验结果表明：（1）与完整试件相比，含有初始缺陷的混凝土试件对应的峰值应力和峰值应变均减小，应力应变曲线在加载初期表现出较为明显的上凹趋势，卸载段曲线更为平缓，但是残余强度的变化没有明显规律。（2）含有初始缺陷的混凝土试件破坏过程可分为4个阶段：裂缝萌生、扩展、聚结、贯穿破坏。（3）当初始缺陷的倾斜角度为0°和90°时，混凝土试件主要以拉伸破坏为主，当初始缺陷的角度为30°、45°和60°时，混凝土试件沿着初始缺陷方向发生剪切破坏。

Failure analysis of concrete with initial defects based on acoustic emission technologys

Initial defects of concrete material play a great role in its deformation and failure properties. We conduct a series of uniaxial compression tests on the initial defects of different sizes and different inclination angles to explore their influence on the deformation behaviors and failure mechanism of concrete, and analyze stress-strain curves, acoustic emission characteristics, and images of crack propagation. The test results show that: (1) Compared with an intact specimen, the peak stress and peak strain in a concrete specimen with initial defects are reduced; the stress-strain curve shows a more obvious concave trend in initial loading stage, and a gentler slope in unloading stage. However, the influence on residual strength presents no obvious pattern. (2) The failure process of concrete with initial defects has four stages of crack development: initiation, propagation, coalescence, and through crack failure. (3) Tensile failure dominates at inclination angles of 0° and 90°, while initial defects at 30°, 45° or 60° cause shear failure along their paths.