隧道洞口浅埋段富水红黏土层造顶施工技术研究

Study on the Construction Technology of Roof Construction in Water Rich Red Clay Layer of Shallow Buried Section of Tunnel Portal

某隧道洞口处于浅埋段,地质情况复杂,在施工过程中出现了两次掌子面塌方,洞口段坡积粉质粘土含水量较高,自稳能力极差,注浆工艺对土体加固无明显效果,针对该隧道地质和现场实际情况,先是对冒顶松散土质坑洞及塌方处前后一定距离采取了一系列处理措施,为保证隧道在安全情况下顺利施工,需要优化或改变原有开挖方案,通过分析制定了洞顶开挖施作钢管混凝土人工造顶方案,彻底改造浅埋段软弱易失稳围岩环境,快速完成了隧道剩余段落的开挖支护及贯通任务。

A tunnel portal is located in a shallow buried section, with complex geological conditions. During the construction process, there were two face collapses. The slope silty clay at the portal section has high water content and poor self stability. The grouting process has no obvious effect on soil reinforcement. In view of the tunnel geology and actual site conditions, a series of treatment measures were first taken for the loose soil cave with roof fall and a certain distance before and after the collapse, In order to ensure the smooth construction of the tunnel under the safe condition, the original excavation scheme needs to be optimized or changed. Through analysis, the scheme of artificial roof construction with steel pipe concrete for tunnel top excavation has been formulated, which thoroughly transforms the soft and unstable surrounding rock environment in the shallow buried section, and quickly completes the excavation support and penetration tasks in the remaining sections of the tunnel.