Study On The Influence Of Pile-anchor Supporting Structure And Diaphram Wall On The Deformation Of Subway Tunnel Of Bilateral Deep Foundation Pit

With a large population distributing densely along the subway route,high-rise buildings and large underground shopping malls construct rapidly,therefore,deep foundation pit engineering increases as well.Soil pressure will unload and the stress of surrounding soil will redistribute accompanying by deep foundation pit excavation,which will bring about influence on subway tunnel nearby and so on.Supporting structure is an important factor to keep stability of foundation pit,the deformation of subway tunnel which is near to deep foundation pit will only have a tiny value when deep foundation pit occurs very small strains and has good stability,consequently,studying the influence of supporting structure on the subway tunnel's deformation can provide a strong basis to supporting structure's design of deep foundation pit close to subway tunnel to ensure the construction of deep foundation pit engineering go on smoothly and the subway tunnel unaffected.This paper taking underground traffic engineering of Zhengzhou comprehensive transportation hub as background,combining the theory of soil mechanics analysis with modeling analysis of finite element software ABAQUS and monitoring data of construction site,studies on the influence of pile-anchor supporting structure and diaphram wall on the deformation of subway tunnel nearby when bilateral deep foundation pit is excavated.The main contents of this paper including:(1)The applicability,structural features,construction technology and failure modes of pile-anchor supporting structure and diaphram wall.(2)Summarize stress and deformation mechanism of pile-anchor supporting structure and diaphram wall when deep foundation pit is excavated,analyze mechanical calculation theory on pile-anchor supporting structure and diaphram wall,and on this basis,summarize the analysis theory of pile-anchor supporting structure and diaphram wall on the influence of subway tunnel's deformation nearby.(3)Taking bilateral deep foundation pit close to subway tunnel(underground traffic engineering of Zhengzhou comprehensive transportation hub)as background,card its general situation of the engineering,geology conditions and hydrological conditions in detail,on this basis,obtain physical and mechanical properties of foundation pit soil and summarize construction scheme of east square engineering.(4)this paper calculates the deformation of subway tunnel when the deep foundation pit of underground traffic engineering of Zhengzhou comprehensive transportation hub is excavated using finite element software ABAQUS,comparing with monitoring data,and analyzes deformation law of subway tunnel nearby while the bilateral deep foundation pit is excavated.(5)Simulate the deformation of subway tunnel of non-supporting structure,pile-anchor supporting structure alone,and both pile-anchor supporting structure and diaphram wall using finite element software ABAQUS,by comparing the deformations of subway tunnel with the three kinds of supporting schemes above,study the pile-anchor supporting structure and diaphram wall's influence on the deformation of subway tunnel of bilateral deep foundation pit.The results prove that:along with the excavation of bilateral deep foundation pit,the subway tunnel emerges settlement deformation,the settlement deformation reduces slightly after adding pile-anchor supporting structure and diaphram wall;the horizontal displacement is increased toward near foundation pit edge,pile-anchor supporting structure and diaphram wall both have the function of reducing the horizontal displacement of subway tunnel,compared with settlement deformation,pile-anchor supporting structure has obvious function of reducing the horizontal displacement of subway tunnel,diaphram wall is the same;the horizontal diameter of subway tunnel increases while the vertical diameter decreases,pile-anchor supporting structure and diaphram wall have the functions of reducing stress concentration phenomenon of subway tunnel.This study provides theoretical basis for the design of supporting structure of deep foundation pit close to subway tunnel.