【摘要】 利用连续损伤理论和统计强度理论,根据岩石微元强度服从Weibull随机分布的特点,定义了弹性模量为岩石热损伤变量,推导了岩石的热损伤演化方程,引入岩石应力—应变曲线特征参量,同时考虑了岩石全过程应力—应变曲线的峰值条件和几何条件,建立了温度效应下岩石的损伤统计本构方程,并通过试验进行验证。试验结果表明:随着轴向应变的增加,岩石损伤经历演化、稳定扩展、损伤加速,直至破坏四个阶段;随着温度的增加,岩石的初始热损伤不断加剧,600℃是花岗岩热损伤的阀值点;损伤本构理论曲线与试验曲线较吻合,所建立的本构模型在岩石峰值前后的拟合明显高于传统方法,但也存在一定的偏差,可能由于在方程建立及参数的确定过程中,进行的假设和忽略对方程的精度产生了影响,本文的研究对建立高温三轴状态下的岩石损伤本构模型具有一定的参考价值。更多还原

【Abstract】 On the basis of continuum damage theory and statistical strength theory,according to the characteristic that rock infinitesimal strength obeys Weibull random distribution,a new thermal damage evolution equation has been derived by defining elastic modulus as a thermal damage variable. A uniaxial damage statistical constitutive equation considering temperature effect has also been established by introducing the characteristic parameter in consideration of the peak and geometry of rock stress-strain curve,and this equation has already been verified by experiments. Test results show that,with the increase of axial stain,the damage of rock undergone four stages:evolution,stable expansion,damage acceleration and destruction; with the increase of temperature,the initial thermal damage of rock increases,and 600 ℃ is the threshold point of granite thermaldamage. The damage constitutive model is in good agreement with the experimental curve,the fitting of the constitutive model to the peak of rock is obviously higher than that of the traditional method,but there are still some differences because the assumption and the negligence may have an effect on the accuracy of the equations during the establishment of the equation and the determination of parameters. This paper has certain reference value to establish the rock damage constitutive model of three axes.更多还原