基于应变率损伤本构模型的围岩分区破裂化现象数值模拟

为了探究深部巷道围岩的分区破裂化现象,利用ANSYS/LS-DYNA软件数值模拟,使用Cowper-Symonds本构模型结合GISSMO模型,将巷道的开挖视为动力过程。从岩石的细观角度出发,考虑岩石的应变率效应以及损伤对岩石的力学性质的影响,构建应变率损伤本构模型。同时结合应力三轴度,以更全面地描述岩石在各种应力条件下的力学特性,并基于最大应变和最大拉应力准则建立单元破坏准则。对岩石进行单轴压缩数值、掘进开挖法模拟及实际观测的结果表明:岩石单轴压缩全应力-应变曲线拟合效果较好;掘进开挖速率对分区破裂化现象有影响;掘进开挖法的分区破裂化模拟结果与实际观测数据具有一定的一致性。提出的模型对于围岩分区破裂化现场的模拟及预测有一定的参考意义。

Numerical Simulation of Zonal Disintegration of Surrounding Rock Based on Strain Rate Damage Constitutive Model

The generation of zonal disintegration of surrounding rock is analyzed by using the numerical simulation software ANSYS/LS-DYNA. Piecewise linear elastoplastic model is used to fit the rock's total stress-strain curve. The excavation of roadways is regarded as a dynamic process by using Cowper-symonds constitutive model in combination with GISSMO model, which take the effects of strain rate and damage on mechanical properties of rock into consideration in mesoscopic scale. Meanwhile, the mechanical properties of rock under various stress conditions are depicted more accurately based on stress triaxiality. The element failure criteria are developed based on maximum strain criterion and maximum tensile stress criterion. The complete stress-strain curve obtained by numerical simulation of uniaxial compression of rock shows good fitting results. According to previous work and engineering practice, the model is modified, and the tunneling and excavation method is adopted in the simulation. The tunneling excavation rate has an impact on the zonal disintegration. Comparison between simulation results and actual observation data demonstrates that the two are consistent.