软土深基坑施工变形规律及对城轨隧道的影响数值分析

NUMERICAL ANALYSIS OF DEFORMATION LAW OF DEEP FOUNDATION PIT CONSTRUCTION IN SOFT SOIL AND INFLUENCE ON URBAN RAIL TUNNEL

以苏州市在建地铁工程作为研究对象,将其按照不同的土层进行划分,针对各个类型土层赋水条件,确定地铁工程的深基坑施工工艺。采用由南至北的分层开挖形式,在各个层级内安置不同的支撑结构,分别为地下连续墙、混凝土支撑以及钢支撑结构。分析支护结构和基坑土体变形规律,得出软土地质具有一定的蠕变性,随着开挖深度的增加以及开挖量的增加,变形量逐渐增加。在此基础上分析其对既有城轨隧道的影响,以当层法构建影响数值验证函数,以土层相对密度对应土层属性,获取深基坑开挖过程中对既有城轨隧道土体的变形影响,其周围土体会存在一定的竖向位移变化,且以隧道拱底的位移变化最为显著。

Taking the subway project under construction in Suzhou as the research object,soil was divided into different layers,and the construction technology for the deep foundation pit was determined based on moisture conditions in different soil layers.Excavation was carried out in layers from south to north,and support structures were set up in each layer,as underground diaphragm walls,concrete supports and steel supports,respectively.The soil deformation law of support structures and foundation pits was analyzed.It was concluded that soft soil has certain creep properties.Deformation rose with the depth and scale of excavation increasing.On this basis,the influence on the existing urban rail tunnel was analyzed.The numerical verification function for the influence was determined by the layering method.The influence of deformation on soil of the existing urban rail tunnel in foundation pit excavation was obtained,according to the soil properties at the corresponding relative density.The soil around the deep foundation pit underwent vertical displacement changes,and the displacement at the bottom of the tunnel arch changed the most.