数字散斑相关方法测定岩石I型应力强度因子

提出一种通过数字散斑相关方法测定岩石I型裂纹尖端位置和应力强度因子的试验方法。采用数字散斑相关方法观测三点弯曲加载条件下，含I型预制裂纹的花岗岩半圆盘试件裂尖区域的位移场，采用牛顿–辛普森方法求解含未知参量的非线性位移场方程组，计算裂尖位置和应力强度因子。研究结果表明，采用该方法可以准确测定岩石I型应力强度因子、裂尖位置及裂纹扩展长度，揭示岩石断裂及裂纹扩展的演化特征。该方法解决以往研究中因不能准确测定裂纹尖端位置，而无法计算岩石断裂参数的难题。

EVALUATION OF MODE I STRESS INTENSITY FACTOR OF ROCK UTILIZING DIGITAL SPECKLE CORRELATION METHOD

An automatic method for determining mode I stress intensity factors(SIFs) and crack tip positions of rock specimens from displacement fields obtained by digital speckle correlation method(DSCM) is proposed. Notched semicircular disk granite specimen under three-point bending are employed for determining the mode I SIFs and the displacement fields around crack tip which are measured by DSCM. Nonlinear displacement field equations with unknown parameters are solved by Newton-Simpson method. The research results show that mode I SIFs，crack tip positions and crack propagation length can be determined accurately from the components of displacement fields；and the characters of rock fracture and crack propagation are revealed. The present method settled the problem of determining stress intensity factors and crack tip position simultaneously in rock fracture testing；so the fracture parameters of rock can be calculated.