Analysis Of The Deformation Influencei Factor On The Supporting Structure Of An Expansive Soil Foundation Pit Slope

On the eastern zone of Chengdu, deformation of an expansive soil foundation pit slope happened in the excavation process. But there are different opinions on the specific factors of the destruction and no clear conclusions yet. Therefore, it is an urgent problem to put forward and analyze the impact of various factors on the destruction;it is also what the construction and design institute most concerns about..This paper starts from an expansive soil foundation pit slope with large deformation and destruction; it analyzes the supporting measures and construction conditions. Firstly it proposes four main affecting factors:excavation and unloading, rainfall, anchor cable construction, and loading on road. Secondly it establishes a full model of an expansive soil foundation pit which size is 270m x 240m x 30m by FLAC3D and a 220 section model which size is 82 m x 10m x 50m. We do the numerical simulation calculation when the models are respectively applied with excavation unloading, rainfall, anchor cable construction, slag car and all of the conditions above together. Meanwhile, the model-establishing process and parameter selection are discussed in this paper. Finally it combines the results of numerical simulation and site-test data, and considers the dynamic load generated from anchor cable construction and the working process of the slag car as the key object to analyze, and excavation unloading and rainfall as less important ones, and then separately simulates influences each factors do to the deformation of expansive soil foundation pit, and analysis of the reasons in depth.Through numerical simulation, the paper makes on the displacement curve when applied with each factors respectively and the measured value in site; a comparison on the displacement curve when applied with all factors together and the measured value; the pile top displacement under all kinds of conditions and the percentages. It comes to a conclusion that many factors jointly lead to the pit slope deformation. The excavation unloading has the minimum influence, it accounts for 15.45% in the simulation displacement; the effect of rainfall and the continuous working process of slag truck are almost same, and they account for 23.81% and 23.24% respectively; the anchor construction has the greatest impact, it accounts for 37.50% in the simulation calculation for displacement, so it can be considered as the main factor.