| With the vigorous development of subway construction,more and more deep foundation pit projects are emerging and mostly located in densely populated urban areas,which caused that the problem of the impact of excavation construction on the surrounding environment has become increasingly prominent.Excavation causes deformation of the retaining structure and the soil outside the pit in practice engineering,which deforms the adjacent building foundation and foundation,causing the building body to have adverse consequences such as inclination and cracking,which are not uncommon.Based on this,it is urgent to study the causes,laws and active protection measures of the foundation and foundation of the building.This is of great significance for the smooth construction of deep foundation pits and the prevention of building damage.According to the deep foundation pit project of Daliang Station in Foshan City,this paper uses the field investigation,construction monitoring method and the numerical simulation method to analyze the deformation law of the foundation continuous underground wall and the surrounding ground surface of the foundation pit,the shallow foundation of the adjacent ancient building and the adjacent building pile foundation during the layered excavation process of the deep foundation pit and the reasons of laws.What’s more,the protection measures for the partition wall between the foundation pit and the building are proposed.The effectiveness of the partition wall is verified by numerical simulation.At the same time,the position parameters,stiffness parameters and embedded soil depth parameters of the partition wall are optimized.The main research contents are as follows:(1)Through the field construction monitoring and results analysis of the foundation pit of Daliang Station,it is obtained that the ground settlement,the horizontal displacement of the ground-connected wall and the settlement law of adjacent buildings,and sorting out the ground settlement,the horizontal displacement of the ground wall and the settlement data of adjacent buildings.And comparing the horizontal settlement of the building settlement with the foundation wall of the foundation pit,the surface settlement and the excavation depth.And it’s obtained that the uneven settlement of the adjacent ancient buildings is related to the location of the surface max settlement,and the maximum settlement value changes with the hysteresis of the foundation wall,and excavation of soil has great influence on building settlement under the depth of pile foundation.(2)Due to the distribution of the Daliang station stratum,the construction of the foundation pit,this paper uses finite element software to build 3D numerical model to simulate the excavation process of the foundation pit by means of “excavation from both ends to the middle and layered sections”,then compares the calculated result data with the field measured data to determine the rationality of 3D numerical simulation,and the deformation law of adjacent building foundation is analyzed under the layered excavation of foundation pit according to the comparative results.On this basis,the settlement law of shallow foundation and pile foundation of adjacent buildings under the most unfavorable working condition of steel bracing prestressing construction(prestress is 0)is analyzed.(3)This paper analyzes the influence of stratified section excavation of foundation pit on settlement of adjacent building foundation under two working conditions: partition wall and non-separated wall,and it is concluded that the partition wall has a significant effect on reducing the settlement of the building foundation by comparing the simulated calculation values.In addition,the effects of partition wall excavation on the foundation of the foundation pit are compared by different positions,different stiffnesses and different depths.Finally,it is obtained that suitable partition wall position,stiffness and depth,which provides reference for guiding the optimization design of foundation pit construction and partition wall. |
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