富水砂层中盾构隧道联络通道施工技术

Construction Technology For Cross Passage of Shield Tunnel in Water-rich Sandy Stratum

在富水砂层中进行联络通道施工,施工难度和风险很大,为提高围岩稳定性、减小施工对周围环境的影响,通过对常用的降水、冷冻、旋喷和注浆等地层加固方法进行技术和经济方面的对比,最终选择了注浆和降水相结合的加固方案。在联络通道施工中采取了洞内超前预注浆、洞外地表管井降水以及洞内轻型井点降水的加固方案,在水仓基坑施工中采取了周边小导管注浆以及坑内轻型井点降水的加固方案。施工过程中对隧道和地表变形进行了监测,由监测结果可知,开挖引起的隧道和地表变形均较小,说明采取的超前预注浆和洞内外降水措施是安全可靠的,可以有效降低联络通道的施工风险。

The construction difficulty and risk of cross passage of urban metros in water-rich sandy stratum is very high. Hence, a comparison is made among dewatering, freezing, jet grouting and grouting reinforcement in terms of technology and economy, and a combination consolidation scheme of grouting reinforcement ＋ dewatering is selected to improve the stability of surrounding rocks and reduce influence of construction on surrounding environment. During the construction of cross passage, advanced pre-grouting in tunnel and tube well dewatering on ground surface ＋ light well point dewatering in well outside tunnel are adopted. During the construction of water pit, surrounding small duct grouting and in pit light well point dewatering are adopted. Meanwhile, the deformation of the tunnel and ground surface during construction is monitored ; and the monitoring results show that the deformation of the tunnel and ground surface is quite small which indicates the safety and feasibility of the above-mentioned technologies.