列车动载作用下隧道底部隆起预应力锚索整治失效机制分析

Failure mechanism analysis of prestressed anchor cable treatment for tunnelbottom heave under train dynamic load

以我国西南某铁路YD隧道典型底部隆起案例为依托,通过分析长达8年的现场监测数据,明确了预应力锚索处置后仍存在的隧底围岩变形难以约束、底部隆起病害持续发展的工程问题,进一步结合数值模拟手段,探究了列车振动荷载作用下缓倾层状岩体运营铁路隧道底部隆起预应力锚索整治的失效机制。研究结果表明:列车动载作用是导致YD隧道底部预应力锚索整治失效的关键因素;在列车动载作用下,预应力锚索出现了整体滑移现象,导致较大程度的预应力损失,难以有效约束隧底隆起发展,最终使锚索整治失效,可见在该病害整治中不宜采用预应力锚索进行加固;同时随列车速度增加,会进一步加剧预应力锚索整治失效现象,在同类病害整治后的逐级提速过程中应引起高度重视,铁路隧道底部隆起病害不宜采用预应力锚索整治方案。

Here,based on a typical bottom uplift case of a certain railway YD tunnel in southwest China,through analyzing 8 years long on-site monitoring data,it was clear that engineering problems,such as,difficulties to restrain deformation of surrounding rock at tunnel bottom and continuous development of bottom uplift diseases still exist after treatment of prestressed anchor cables.Further combining numerical simulation methods,the failure mechanism of treatment of prestressed anchor cables for bottom uplift of railway tunnels operating in gently dipping layered rock under train dynamic loads was explored.The study results showed that train dynamic load is key factor leading to failure of treatment of prestressed anchor cable at bottom of YD tunnel;under train dynamic load,prestressed anchor cable has a phenomenon of overall sliding to cause larger prestress loss,being difficult to effectively restrain development of tunnel bottom heave,and ultimately making anchor cable treatment failure,so it is not appropriate to use prestressed anchor cable for reinforcement in this disease treatment;with increase in train speed,failure of prestressed anchor cable treatment can be further exacerbated,this phenomenon should receive high attention in gradually increasing train speed process after the treatment of similar diseases,the treatment scheme with prestressed anchor cable is not appropriate to adopt for uplift disease at bottom of railway tunnel.