Study On The Influence Of Existing Buildings On The Deformation Performance Of Excavation

The Technical Specification for Retaining and Protection of Building Foundation Excavation(JGJ120-2012)have clear requirements for the functions to be satisfied by foundation pit support,first ensuring the safety and normal use of buildings(structures),underground pipelines and roads around the foundation pit.Secondly,the construction space of the main underground structure is guaranteed.It can be seen that in the design and construction process of the supporting structure,the environmental safety around the protection pit is placed at the top position.Along with the development of urban society,the building density has increased sharply,and the construction of super-deep foundation pits has gradually increased.Due to the increasingly complex surrounding environment,this has brought great challenges to the design and construction of ultra-deep foundation pits.Based on this background,this paper studies and analyzes the deformation characteristics of foundation pits for surrounding buildings.This paper mainly carried out the following work:1.Systematic overview of " Technical Specification for Retaining and Protection of Building Foundation Excavation "," Technical Specification for Retaining and Protection of Building Foundation Excavation ","Technical Code for Excavation Engineering" A calculation method for the earth pressure of the supporting system under the three special conditions of local uniform load at the top of the foundation pit,full uniform load and the support system is lower t han the top of the pit.2.Taking a deep foundation pit project in Lanzhou as the research object,firstly,the specificity of each segment of the foundation pit engineering is analyzed and summarized in detail,and then the west side of the foundation pit is analyzed,and the rational foundation pit is utilized.The support structure design software analyzed the pile displacement and the pile bending moment using three different specifications on the side.3.Based on a deep foundation pit project in Lanzh ou,the numerical analysis of the west side profile of the foundation pit was carried out using the geotechnical numerical analysis software Plaxis 3D V2017.The soil constitutive model used small strain soil during the analysis.Hardening model,which can well consider the different values of soil loading and unloading modulus.The main research contents are the bending moment,displacement,vertical displacement of foundation pit and the variation of surface settlement under each working condition,and th e calculation results are compared with the calculation results of rational design software.In addition,the trend of the internal force and deformation of the pile and the deformation of the foundation pit under the condition that the length of the origi nal building foundation and the length of the supporting pile are changed are also analyzed.