紧邻地铁隧道上软下硬地层超深基坑施工变形控制

Deformation Control of Ultra-Deep Foundation Adjacent to Metro Tunnel in Upper Soft and Lower Hard Strata

以紧邻深圳地铁线11号线某超深基坑工程为例,介绍上软下硬地层基坑支护结构施工和开挖过程中采取的变形控制技术,包括双重护槽和三机联动地下连续墙施工技术、坑底破碎带交替双液注浆技术、钢筋混凝土支撑轴力伺服技术等,并通过三维精细化数值模拟与监测数据的对比分析,验证上述施工技术的有效性。在此基础上探讨了基坑内支撑预加轴力影响下最大侧向变形/开挖深度关系曲线,分析其对既有地铁隧道的保护效果。

Taking an ultra-deep foundation pit project adjacent to Shenzhen Metro Line 11 as an example,this paper introduced the deformation control technology adopted during the construction and excavation of the foundation pit support structure of the upper soft and lower hard strata,including the construction technology of double guard trough and three-machine linkage underground continuous wall,the alternating double liquid grouting technology of the crushing belt at the bottom of the pit,and the axial force servo technology of reinforced concrete support.Through the comparative analysis of three-dimensional refined numerical simulation and monitoring data,the effectiveness of the above construction technology was verified.On this basis,the relationship curve of maximum lateral deformation/excavation depth under the influence of pre-applied axial force in the foundation pit was discussed,and its protective effect on the existing subway tunnel was analyzed.