Analysis Of The Influence Of Metro Deep Foundation Pit Construction On Different Structure System Buildings

With the rapid development of China's economy,the pace of urban development is getting faster and faster,and urban traffic problems have become one of the main factors restricting urban development.In order to meet the urban traffic demand and ease the ground traffic pressure,the city subway has received the attention of the state and the government,and the rapid development of the city subway has also brought a large number of deep foundation pit projects.In the deep excavation soil excavation process to ensure the smooth construction of the foundation pit and the safety of the surrounding risk source is the most basic and most important requirement of the deep foundation pit engineering,but the soil around the deep foundation pit during the excavation of the foundation pit soil Because the soil unloading action in the foundation pit occurs vertical displacement and horizontal displacement,the load generated by the surrounding buildings on the soil will also aggravate the deformation of the soil.When the soil deformation reaches a certain level,it will lead to the envelope structure and adjacent buildings.Deformation,affecting the construction safety of the foundation pit and the function and comfort of the building.In severe cases,the foundation pit may collapse or the surrounding buildings may be structurally damaged.Especially nowadays,the city is developing rapidly,and there are often some new and old buildings in the urban area.Therefore,how to reduce the deformation of the surrounding structure caused by the construction of deep foundation pits,surrounding soil and adjacent buildings has become one of the most difficult points in the construction process of the subway.This paper combines the deep foundation pit excavation of the main station of Beidaiying Street Station of Shenyang Metro Line 10 to study the interaction between the retaining structure and adjacent buildings in different structural forms during the construction of deep foundation pit.This paper mainly analyzes the settlement and deformation laws of the retaining structure,surrounding soil and adjacent buildings during the excavation of deep foundation pits,evaluates the safety and stability of deep foundation pits and buildings,and proposes corresponding solutions.The main research work of this paper is as follows:(1)Combining the characteristics of the deep foundation pit retaining system and the deformation mechanism of the surrounding soil during the excavation of deep foundation pits,the related theories of the influence of deep foundation pit excavation on adjacent buildings with different structural forms are introduced.(2)Through the analysis of the on-site monitoring data,the variation rules of the envelope structure deformation,surface settlement and building settlement during the construction process of the deep foundation pit project are summarized.The MIDAS/GTS NX is used to establish the deep foundation pit engineering,the soil outside the pit and the building integration model,and the software simulation calculated values are compared with the measured values to verify the accuracy and applicability of the model.(3)Change the working conditions of the model and related calculation parameters,respectively simulate different construction conditions(relative position of building and foundation pit in different structural forms,depth of retaining wall,thickness of retaining wall,pre-addition of steel support)Force,steel support stiffness)deformation rules of foundation pit retaining structure and adjacent buildings,optimize the design.(4)In view of the adverse effects of deep foundation pit construction on adjacent buildings with different structural forms,this paper carries out three building protection measures(optimal design of-foundation pit construction scheme,addition of partition wall outside the pit,grouting reinforcement of building foundation).Analyze and discuss the protective measures applicable to the horizontal displacement of the retaining structure and the buildings of different structural forms.(5)By analyzing the monitoring data collected in the field,it can be concluded that with the excavation of deep foundation pit,the horizontal displacement of retaining piles increases steadily and the displacement curve presents a parabola shape.The maximum lateral deformation of pile is 0.2%?1%foundation pit excavation depth.When the design and construction of retaining structure is good,the maximum displacement point is generally located in the middle and upper part of the supporting structure,and the maximum value is about 50%of the control value.The anti-deformation ability of the frame structure pile foundation structure is better than that of the brick-concrete structure.When the foundation pit is excavated to the bottom of the pit and the supporting system is built,the monitoring of all monitoring projects will be carried out.The measured data tend to be stable.(6)The overall stability and safety of foundation engineering can be improved by optimizing the design scheme of envelope structure and grouting strengthening of building foundation,in which the optimization of envelope pile has a great influence on the deformation of envelope structure,and so on,and the engineering measures such as grouting and strengthening of building foundation can improve the overall stability and safety of foundation engineering.Grouting reinforcement of building foundation can improve the overall stability and safety of the building.In the actual project,we should fully investigate and draw up a safe and economical construction plan according to the engineering condition and the surrounding environment.