基于Hoek-Brown准则的隧道围岩塑性变形研究

Plastic Zone Analysis of Tunnel Surrounding Rock Based on Hoek-Brown Criterion

基于Hoek-Brown准则,推导了考虑应力重分布(不考虑地下水作用)的深埋圆形隧洞弹塑性区应力位移计算公式。并对不同地质强度指标GSI、围岩类别、支护力和初始应力对围岩塑性区半径和位移的影响进行了分析。在GSI取相同值时,不论岩石的种类,初始地应力对围岩塑性区的应力和位移都有较大的影响,尤其是在初始地应力大于15 MPa时影响效果明显增大。将现场观测的围岩累计沉降值和塑性区范围与理论值计算值对比分析发现,围岩累计沉降按斜率可划分为严重扰动区、中度扰动区和微扰动区,且塑性区范围与实际观测结果较为接近,围岩剧烈变形区域集中在距围岩表面0.8 m范围内,其变形量占理论计算值的90%左右,可以为以后类似工程提供参考。

Based on Hoek-Brown criterion,a formula for calculating stress displacement in elastic-plastic zone of deep circular tunnel considering stress redistribution(without considering groundwater action)is derived.The influence of GSI,type of surrounding rock,support force and initial stress on the radius and displacement of plastic zone of surrounding rock is analyzed.When GSI is the same,no matter the type of rock,the initial in-situ stress has a great influence on the stress and displacement in the plastic zone of surrounding rock,especially when the initial in-situ stress is greater than 15 MPa.Accumulated subsidence value and the in-situ observation of surrounding rock loose circle range with the theoretical value calculated value analysis and comparison,the cumulative settlement of surrounding rock in the slope zone can be divided into serious disturbance,moderate disturbance and micro perturbation,and the plastic zone range is close to the actual observation and severe deformation of surrounding rock area from concentrated in surrounding rock indicates that within the scope of 0.8 m.The deformation is about 90%of the theoretical calculation value,which can provide reference for similar projects in the future.