小净距隧道围岩稳定性的影响因素

Influence factors of surrounding rock stability of neighborhood tunnel

近年来市政隧道工程蓬勃发展,许多城市公路隧道受建筑、管线等因素的限制,并为节约用地、缩短工期等目的,大多被设计成小净距隧道。小净距隧道在施工过程中与分离式隧道最显著的区别是中隔岩柱受力状态复杂、稳定性难以控制。通过理论推导,对浅埋超小净距隧道土质中隔岩柱的失稳机理进行系统研究,基于小净距隧道中隔岩柱承载模型确定中隔岩柱上覆应力,结合土体极限应力公式对中隔岩柱在不同施工条件下的失稳破坏特征进行分析。结果表明,增大土体的黏聚力、内摩擦角及支护反力均能提高土体的极限应力,且增加支护反力效果更显著。

In recent years,municipal tunnel engineering has developed vigorously.However,many urban highway tunnels are restricted by factors such as construction and pipelines.In order to save land and shorten the construction period,most of tunnels are designed as neighborhood tunnels.The most significant difference between neighborhood tunnel and separated tunnel in the construction process is that the force state of the mid-adjacent rock is complicated and the stability of the rockis difficult to control.Through the theoretical derivation,the instability mechanism of the soil mid-adjacent rock in shallow neighborhood tunnel has been studied.The overburden pressure of mid-adjacent rock is determined based on the load-bearing model of the neighborhood tunnel's mid-adjacent rock.Combined with the ultimate stress formula of the soil,the instability and failure characteristics of mid-adjacent rock under different construction conditions have been analyzed.The research results show that increasing the cohesive force,internal friction angle and support reaction force of the soil can all increase the ultimate stress of the soil,and the effect of increasing the support reaction force is more significant.