水压力作用下岩石统计损伤本构模型研究

A Statistical Constitutive Damage Model for Rock under Water Pressure

为了探究水压力对岩石损伤的影响,在多孔材料弹性理论框架内,利用有效应力原理,结合连续损伤力学和统计理论把霍克-布朗(Hoek-Brown)准则作为微元体强度破坏准则,建立水压力作用下的岩石统计损伤本构模型;并根据残余强度和峰值强度的关系对损伤变量进行修正,使模型能够更好地反映岩石峰后阶段的软化特征。通过室内试验进行模型验证和参数分析,结果表明:建立的模型能够较好地反映水压作用下岩石的应力-应变关系;随着水压力的增大,模型参数n呈增大趋势,岩石的脆性度增高,参数F0呈减小趋势,岩石的强度降低;峰值点法在确定模型参数时优于曲线拟合法。研究成果对于水压力作用下岩体工程的安全分析有一定的参考价值。

A statistical constitutive damage model was developed within the elastic theory frame of porous materials to investigate rock damage characteristics under water pressure. By incorporating continuum damage mechanics and statistical theory with the principle of effective stress, the Hoek-Brown criterion was regarded as a microbody strength failure criterion. According to the relationship between residual strength and peak strength, the damage variable of the model was modified for fully reflecting the softening characteristics in the post-peak stage. The model was validated using indoor experimental data. Results evinced the established model could well reflect the stress-strain relationship of rock under water pressure. As water pressure increased, the value of model parameter n exhibited a rising trend and the brittleness of rock also increased, but the value of F 0 and the strength of rock both declined. In addition, peak point method is better than curve fitting method in determining model parameters.