不利条件下盾构近距离下穿地铁出入口施工技术研究

Research on Construction Technology of Shield Under-crossing Subway Entrance and Exit at Close Distance Under Unfavorable Conditions

富水砂层、超小半径、全曲线、大坡度等不利施工条件下,盾构近距离下穿既有地铁车站出入口面临孔隙水压大、土压平衡难以建立、掘进姿态控制要求严格、既有建筑物保护标准高、成型隧道易发生管片破损与渗漏等多方面问题。施工过程中要通盘考虑多方因素、加强技术指导,确保安全下穿。本文以某城市不利条件下盾构近距离下穿既有地铁车站出入口施工为例,提出了一系列具体技术措施。

Under unfavorable construction conditions such as water-rich sand layer,ultra-small radius,full curve and large slope,the shield under-crossing the entrance and exit of the existing subway station at close distance faces many problems,such as large pore water pressure,difficult to establish earth pressure balance,strict requirements for excavation attitude control,high protection standards of existing buildings,and easy to cause segment damage and leakage in formed tunnels.During the construction process,it is necessary to comprehensively consider many factors and strengthen technical guidance to ensure safe under-crossing.This paper takes the construction of shield under-crossing the entrances and exits of existing subway stations at close distance under unfavorable conditions in a city as an example,and puts forward a series of specific technical measures.