缓倾层状岩体大断面高铁隧道变形特征研究

Study on Deformation Characteristics of High Speed Railway Tunnel with Large Section Through Gently Inclined Layered Rock

隧道穿越缓倾层状围岩时,易发生剪切滑移、张拉破坏和弯折内鼓等现象,致使隧道施工过程中易发生拱顶掉块、塌方等问题。以重庆楠竹山隧道为工程依托,研究不同岩层倾角下隧道结构受力、变形特征以及塑性区分布规律,并探讨缓倾层状岩体隧道变形控制措施。研究表明:当缓倾层状岩体节理角度由0°增加至15°、30°时,隧道最大竖向位移变化不大,但节理角度增大对隧道水平位移的影响较大,最大水平位移主要发生在拱腰至边墙部位;隧道周边围岩塑性发展及破坏区受缓倾层状岩体节理角度的控制较为明显,当层状岩体倾角为0°、15°时,塑性区以压溃破坏为主,当层状岩体倾角为30°时,塑性区主要以层间剪切滑动破坏为主。研究有助于采取针对性措施以保证施工安全。

When the tunnel passes through the gently inclined layered surrounding rock,shear slip,tensile failure and bending inner drum are easy to occur,which makes the arch block fall and collapse easily occur in the tunnel construction process.In order to solve the problems encountered in tunnel construction through gently tilting layered rock mass,taking the Nanzhushan Tunnel in Chongqing as a project,the stress and deformation characteristics of tunnel and the distribution law of plastic zone under different angles are studied,and the deformation control measures of tunnel in gently inclined layered rock mass are further discussed.The results show that the maximum vertical displacement of the tunnel changes little when the joint angle of the gently inclined layered rock mass increases from 0°to 15°and 30°,but the increase of the joint angle has a great effect on the horizontal displacement of the tunnel,and the maximum horizontal displacement mainly occurs from the arch waist to the side wall.The plastic development of the surrounding rock and the failure zone of the tunnel are obviously controlled by the joint angle of the gently inclined stratified rock mass.When the dip angle of the stratified rock mass is 0°and 15°,the plastic zone is mainly dominated by crushing failure,while when the dip angle of the stratified rock mass is 30°,the plastic zone is mainly dominated by interlayer shear sliding failure.The research is benifical to adopt the effective measures to ensure constriction safety.