Research On Construction Optimization Of Underground Comprehensive Pipe Gallery

With the acceleration of the pace of urban modernization,urban problems such as large population density,tight construction land,and traffic congestion have become increasingly prominent.The underground integrated pipe gallery combines the underground commercial street with the underground pipe gallery,which can not only divert the crowd,but also manage the underground pipelines in a unified way.It also can alleviate the population and traffic pressure.The underground integrated pipe gallery is generally built under the urban roads.It is often faced with problems such as narrow site,complicated surrounding buildings and chaotic underground pipe network.The reverse construction can adapt to complex construction conditions.This paper takes the Zhengzhou Erqi Road,Taikang Road Integrated Pipe Gallery and underground space development project as the research background and uses the finite element analysis software Midas/GTS NX to establish a three-dimensional model Then the numerical simulation of the construction phase of the project is carried out,and the simulation results are analyzed from the horizontal displacement of the retaining structure,the surrounding soil settlement and the soil uplift at the bottom of the foundation pit.The rationality of the model is verified by the design data.Three construction optimization schemes are proposed,and numerical simulation is also carried out.Through the comparative analysis of the data,the optimal scheme is selected from them and provides reference for engineering design.The main conclusions of the study are as follows:(1)Through the analysis of the results of the numerical simulation of the Erqi Road Comprehensive Pipe Gallery Project,it can be seen that when using the up-down method,after the construction of the retaining pile,before the soil excavation,if there is a “sandwich” formation in the geology where the retaining pile is located,that is,the mechanical properties of the intermediate soil layer is very different from the mechanical properties of the upper and lower soil layers,then the enclosure structure will have less deformation near this depth.The horizontal displacement of the retaining structure,the settlement of the surrounding soil and the uplift of the soil at the bottom of the foundation pit will increase with the increase of the excavation depth of the foundation pit,but the horizontal displacement will be limited by the structural beam plate during the growth process.The surrounding soil settlement is affected by the retaining structure,and the uplift of the pit bottom is affected by the intermediate column pile.(2)Three optimization schemes for optimizing the distance between the retaining piles,increasing the bolts,jointly optimizing the distance between the piles and increasing the anchors are proposed.According to the analysis of the simulation results,the horizontal displacement of the retaining structure and the surrounding soil settlement will increase with the increase of the pile spacing during the up-down method,but the impact of the soil bottom uplift is not obvious.Increasing the bolt can only restrain the horizontal displacement of the retaining structure near the set position,and has no obvious influence on the surrounding soil settlement and the soil uplift at the bottom of the foundation pit.By contrast,the joint optimization scheme is economical and can guarantee the safety of the project.