盾构隧道穿越江底溶洞发育区若干关键技术探析

An Approach to Some key Technologies of Shield Tunnel Construction in Karst Development Area under River Bottom

地铁盾构区间穿越江底岩溶发育区在全国尚属首例,难度极大。以长沙地铁3号线为工程依托,总结盾构区间穿越湘江下方溶洞群的关键技术。湘江西河汊320m范围内串珠状溶洞集中发育,岩溶水与湘江存在水力联系,盾构施工易引起溶洞坍塌、涌水、机器陷落等突发状况,风险较大,通过工程分析、类比和归纳等方法,提出江底岩溶区盾构工程的风险和重难点,并对溶洞专项勘查、加固方案、注浆参数,特别是串珠状溶洞加固措施以及加固检测标准等进行详细阐述,并结合类似工程实践经验对以上关键技术提出设计施工原则和相关建议。

As the first engineering project in China,the tunnel of subway passing under karsts region in the bed of river has great difficulties in technology and construction. With reference to Subway Line 3 of Changsha,this article is mainly concentrated on key technologies of tunnel passing karst caves under river. Caves are accumulated west branch of Xiangjiang River and the length of region with caves from east to west is about 320 meters. In the longitudinal direction,there is a series of caves and some of them have connection with the river and collapsing,water gushing,machine falling and other accidents are likely to occur during shield tunneling. The risks and key points of construction are put forward based on engineering analysis,analogical and summary method,and dedicated investigation,reinforcing scheme,grouting parameters,especially reinforcing process and inspection standard are described in detail.Meanwhile, design and construction principles, relevant suggestions associated with above key technologies are provided in accordance with the practices in similar projects.