砂卵石地层超浅埋小净距暗挖群洞施工探析

成都地铁4号线清江路口站北侧附属大部分位于新近建成的成温射线立体交通系统投影下,原设计明挖方案无法实施,采取通道及风道合建暗挖结构方案。暗挖小净距群洞方案存在浅埋、大断面、群洞效应、环境复杂、工期紧张等特点。为了减少群洞效应影响,采取管棚联合导管超前支护、超前加固+径向注浆改良周围地层、分块分部错进、二次衬砌保留部分临时支护钢架等措施,结合相应附属明挖基坑,实现多工序平行交叉作业。通过上述措施,实现了快速安全施工,并且对主道交通无任何影响。

Research on Construction Technologies for Super-shallow-covered and Close-spaced Mined Multiple Tunnels in Sand and Gravel Strata

The auxiliary works of Qingjianglukou station on Line 4 of Chengdu Metro are originally designed to be constructed by cut and cover method. However, most of these auxiliary works are located below the newly built Wenshe viaduct line, therefore mining method is adopted for these auxiliary works. These close spaced mined tunnels have such features as shallow cover, large cross section, multiple tunneling effect, complex environment and tight construction schedule. Parallel working is achieved for the construction of the auxiliary works by using the open cut foundation pits; countermeasures, including pipe roof supporting, forepoling, radial grouting, sequential excavation and incorporating some steel arches into the secondary lining, are adopted to minimize the multiple tunneling effect. In the end, safe and rapid construction of the auxiliary works are achieved, without influence to the operation of the viaduct line.