新建地铁隧道下穿既有地铁车站工程中通常需要穿越车站两端的地下连续墙围护结构,如果地下连续墙没有预留玻璃纤维筋,盾构隧道难以直接穿越,需要人工凿除地下连续墙,凿除过程中洞门附近土体产生变形,影响既有车站的安全运营,需对土体进行加固,以保证土体稳定性和减小既有车站变形.以苏州拟建8号线地铁隧道下穿既有1号线华池街站和地下连续墙围护结构为例,提出采用水平人工冷冻加固洞门附近土体,采用极限平衡理论推导了洞门土体稳定性的计算公式,分析了土体稳定性的影响因素,比较了在有无土体加固情况下的土体稳定性系数,同时采用三维有限元对地下连续墙凿除过程进行数值模拟,数值模拟和理论公式计算的土体稳定性系数吻合良好.%Tunneling beneath existing subway station typically requires passing through concrete diaphragm walls used as excavation support during construction of the station.When the concrete diaphragm walls were not reinforced by fiber glass,it is difficult for the shield machine to tunnel through them which have to be broken by man-power.The breakage of concrete diaphragm walls induces deformation of soil body beneath the existing subway station and impacts the normal operation of the station.As such,soil improvement is required to protect the stability of the soils.This paper deals with the stability analysis of the soil body during the breakage of concrete diaphragm walls using the Suzhou metro line 8 passing beneath existing metro line 1 Huachi Street station as an example.A theoretical formulation is developed for predicting the soil stability.The factors impacting the soil stability are analyzed and the stability number with and without ground improvement are compared.Three dimensional finite element analyses are performed to simulate the process of concrete diaphragm wall breakage.The simulation results were compared with the theoretical analysis results.
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