复杂条件下连拱隧道洞口塌方成因及加固技术

栎斜隧道是宁波象山港大桥公路中的一座双向四车道连拱隧道,出口段存在明显的偏压现象,围岩较破碎,地质条件复杂.左洞出口段遇大雨侵蚀后围岩变形突然增大,变形速率加快,致使洞口出现塌方.通过对塌方段主客观原因的分析,采用洞口刷坡、打设长管棚并喷射混凝土的综合方法加固处理.同时在处理段洞内增设监测断面进行周边收敛位移、拱顶下沉和地表沉降监测等监控手段,并与数值模拟结果对比分析.监控量测和数值模拟结果基本相同,表明处治措施得当,隧道洞口围岩基本趋于稳定,效果良好,为类似工程提供参考.

Portal section collapse reason and reinforcement technology of complex conditions double-arch tunnel

Lixie Tunnel is locted in Ningbo, China. which is a multi-arch tunnel of bidirectional four roadways on Xiangshangang port bridge road. There are complex geologic conditions, broken surrounding rock and obvious unsymmetrical pressure phenomenon. The surrounding rock deformation of the left hole of portal section was suddenly becoming increased after heavy rain erosion, accelerated rate of deformation, and collapse appeared. Based on the analysis of the objective and subjective of collapse reason, the brush slope treatment , long pipe shed methods and sprayed concrete were designed for reinforcement tretment, at the same time , a new monitoring section was designed in the collapse section of the left hole to observe convergence displacement, vault subsidence and surface subsidence, and treatment construction process of tunnel collapse section was simulated by FLAC. The comparative results show that the monitoring measurement and numerical simulated results is same, the surrounding rock of portal section is basically stabilized after treatment and get good results. It provide a reference for similar projects.