高地应力破碎围岩隧道变形受力特征试验研究

高地应力破碎围岩地层在开挖隧道过程中极易发生大变形、钢架扭曲、局部垮塌等灾害。以天平铁路关山隧道为依托,通过监测两个试验段内的围岩压力、初期支护受力与变形、二次衬砌混凝土应力的分布特征,来探讨高地应力破碎围岩地层中不同断面形式和支护参数情况下隧道支护结构的变形与受力特征。结果表明:在以水平地应力为主的破碎围岩地层中,隧道开挖引起的变形以边墙水平收敛为主,拱顶沉降次之;高边墙小曲率断面形式的单线铁路隧道受力和变形均较大,而增大边墙曲率可有效抑制隧道开挖引起的变形,使支护结构受力更为均匀,受力状态明显改善。研究可为高地应力破碎围岩地层中隧道设计提供一定的参考。

Experimental Study on Deformation and Stress Characteristics of Tunnels With Fault Zone Surrounding Rock Under High Ground Stress

In environment of high ground stress and fault zone surrounding rock Stratum, disasters such as large deformation, steel frame distortion and local collapse are easy to occur when tunnel is excavated. Taking the Guanshan Tunnel of the Tianping railway as an example, through monitoring the surrounding rock pressure, the force and deformation of initial support, and the stress distribution characteristics of secondary lining concrete in two test sections, the deformation and stress characteristics of tunnel support structure under different section forms and support parameters in high geostress fractured surrounding rock strata are discussed. The results show that: in the fractured surrounding rock strata with horizontal in-situ stress, the deformation caused by tunnel excavation is mainly lateral wall horizontal convergence, and vault settlement followed. The stress and deformation of single-track railway tunnel are larger in section form of high lateral wall and small curvature. Increasing the curvature of the side wall can effectively restrain the deformation caused by tunnel excavation, and it makes the supporting structure bear more uniform force and improves the stress state of the supporting structure. The measures of radial bolt grouting, advance pre-support and increasing the reserved deformation can effectively control the deformation of surrounding rock and reduce the construction risk. The study can provide some reference for tunnel design in high ground stress fractured surrounding rock strata.