直墙式黄土隧道围岩结构的地震动稳定性分析——底脚处应力集中对安全系数的影响

Earthquake stability analysis of wall rock of vertical ridge loess tunnel——the impact of stress concentration at tunnel feet on safety factor

为了验证直墙式黄土隧道(洞)底脚处应力集中现象对围岩结构安全系数的影响,本文根据静力和动力分析模型,应用抗剪强度折减法和ANSYS软件,在现有研究的基础上,分析了底脚为直角时重力和地震作用下塑性区和安全系数的变化规律,并通过数值算例,研究了底脚为不同半径圆弧时围岩结构安全系数的变化情况。结果表明:在重力作用下塑性区最先出现在底脚偏上,直角的应力集中现象对围岩结构安全系数没有影响,地震作用下塑性区虽然最先出现在底脚处,但安全系数的降低并非底脚处应力集中现象的影响,从而为以后工程结构中直墙式隧道(洞)的成型和工程应用提供了理论依据。

The impact of stress concentration at the feet of vertical ridge loess tunnel（hole） on the rock structure safety factor was examined,according to the static and dynamic analysis model,by using the shear strength reduction method and the ANSYS software.Based on the existing study results,the change of plastic zone and the safety factor were analyzed under the action of gravity and seism with right angles feet of vertical ridge loess tunnel（hole）,and through numerical examples the change rules of rock structure safety factor were studied with arc angles feet of different radius.The results show that： the plastic zone under the gravity action appears initially at the upper foot of the tunnel（hole）,the stress concentration at right angles feet has no effect on wall rock safety factor;the plastic zone under earthquake action appears initially at the right foot of the tunnel（hole）,but the decrease of safety factor is not mainly due to the stress concentration.So a theory basis will be provided,the study provides a theoretical base for the construction of vertical ridge loess tunnel and its engineering application.