非线性硬化与非线性软化的巷、隧道围岩塑性分析

Plastic analysis of surrounding rock of tunnel based on strain nonlinear hardening and nonlinear softening

在符合岩体实际的弹性、应变非线性硬化和具拐点的非线性软化的三段式光滑连接应力-应变关系条件下,求得静水压力下圆形巷、隧道围岩塑性硬化区和软化区的应力分布表达式。证明了所求得的巷道围岩径向和切向应力曲线在硬化区半径r=Rs和软化区半径r=R处均光滑连接,特别是所求得的切向应力σθpo-r a曲线没有尖峰向上的应力集中,此结果与日本学者久武胜保的试验结果一致。指出基于理想弹、塑性本构模型的Kastener解有明显缺陷,其σθ-r曲线尖峰向上的应力集中与实际不符。

Based on according completely with practical constitutive relation of rock, i.e. relation between stress and strain that is linked glossily by three segments composed of elastic, strain nonlinear hardening and nonlinear softening segment having inflexion, the stress distribution laws of surrounding rock in plastic hardening and softening zone of circular tunnel under the condition of hydrostatic pressure is deduced. It is proved that the obtained radial and tangential stress curve link glossily at hardening zone radius r = R, and softening zone radius r = R, and curve of tangential stress σθ/po-r/a has not up-pinnacled stress concentration especially, the result goes all the way with the experiment result of Japanese scholar Jiuwubosheng. The paper points out that there is obvious limitation in Kastener formula based on ideal elastoplastic constitutive model, and up-pinnacled stress concentration of σθ-r doesn＇t correspond with practice.