明挖隧道施工期间下方共线地铁盾构区间上浮控制技术——以深圳市桂庙路快速化改造工程为例

深圳市桂庙路快速化改造工程与下卧深圳地铁11号线平面共线长达3 km。为解决上方基坑开挖过程中引起的下方既有地铁运营盾构区间上浮变形问题,在施工期对下卧盾构区间隧道进行长期自动化监测的基础上,结合数值分析计算,确定下卧地铁盾构区间产生上浮变形的原因。在对比分析开挖工况、地质条件、结构施工和开挖范围及长度等因素对盾构隧道上浮变形影响规律的基础上,结合项目施工上浮控制经验,提出三重高压旋喷桩和三轴搅拌桩地层加固、调整结构施工工序并采用分幅施工方案、提前施作竖井+抗浮板+抗拔桩等地铁盾构区间上浮变形控制措施。现场实践表明,竖井+抗浮板+抗拔桩措施对地铁上浮控制十分有效,能够确保基坑施工期间下卧地铁的运营安全。

Floating Control Technology of Lower Collinear Metro Shield Section during Cut-and-cover Tunnel Construction: a Case Study of Rapid Rehabilitation Project on Guimiao Road in Shenzhen

The rapid rehabilitation project on Guimiao Road in Shenzhen is 3 km long with the plane line of Shenzhen Metro Line 11. The floating deformation of the existing lower shield tunnel during foundation pit excavation should be controlled. Hence, on the basis of long-term automatic monitoring of the lower collinear metro shield tunnel during the construction period, the causes for deformation and floating of the underlying metro shield section are analyzed and determined by numerical analysis and calculation. And then the floating control technologies, i.e. ground reinforcement by triple-tube high-pressure jet grouting pile and triaxial mixing pile, adjusting the construction procedure of structure and adopting the split construction scheme, and construction of vertical shaft + anti-floating plate + anti-pulling pile in advance, etc., are put forward based on comparative analysis of the influences of excavation conditions, geological conditions, structural construction and excavation range and length on the floating deformation of shield tunnel, as well as the experience of floating control in project construction. The field practice shows that the measure of shaft + antifloating plate + anti-pulling pile is effective for the floating control of the shield section, which can ensure the operation safety of the lower metro shield tunnel during foundation pit construction.