The Study On The Deformation Rule Of The Pile Anchor Supporting Slop Of Deep Expansive Foundation Pit

In recent years, the development of urbanization in our country has grown fast. The construction scale is more and more big. At the same time it’s accompanied by the emergence of a large number of deep excavation engineering. The stability of deep foundation pits of expansive soil is getting more and more attrition. The pile-anchor supporting structure become more and more popular as with high efficiency and low cost advantages, but the application of it in expansive foundation pits is still worth exploring.A expansive soil foundation pit in the eastern part of the Chengdu as the research object, analysis the pile anchor supporting design principle. We install the inclinometer, steel stress meter and other monitoring and get the date of pile displacement and variation of stresses. On the basis of that to analysis the stress strain response of the structure as the excavation process. According to the study of the relationship of expansibility and the moisture content, and based on the site conditions to determine the excavation expansion force. Using FLAC simulation software, establish a foundation pit model with considering the expansion force, and to verify it with the reaction of the supporting structure under different working conditions. At the same time through the model to simulate the deformation of the pile anchor supporting structure under the different excavation sequence or the different coaxial force.The main research results are as follows:Using FLAC simulation software, establish a foundation pit model with considering the expansion force. Through the model to simulate the deformation of the structure, model calculation value is closed to the actual monitoring result. So model with considering the expansion force is conforming to the actual situation. Through the model to simulate the deformation of the pile anchor supporting structure under the different excavation sequence or the different coaxial force, we can draw a conclusion that increasing the anchor axial force and stratified excavation can reduce the displacement of pile body in different degrees. The contrast of field monitoring value and numerical simulation shows that the force is reasonable and the pile deformation control well. The pile anchor supporting structure has played a good supporting location, but the current design uses the method of reduction parameters on the swelling force calculation are still insufficient.