Study On Deformation Law Of Pile-Anchor Supporting System For Deep Foundation Pit

With the vigorous development of national economic construction and the continuous increase of urban population,people are turning their attention to the development and use of underground space and expanding the scale of underground space.Therefore,the problems faced by deep foundation pit engineering are becoming more and more complex and the degree of danger is increasing.How to ensure the stability of deep foundation pit engineering safely,economically and efficiently has become a major problem.A problem for several researchers.Therefore,it has become a more and more important research content to study the internal force and deformation evolution law of retaining wall structure of deep foundation pit in order to meet the needs of practical engineering in the aspects of economy,safety and applicability.In this paper,the internal force and deformation law of retaining wall structure with pile-anchor support in deep foundation pit are studied and analyzed based on practical engineering.The numerical simulation analysis and internal force deformation law of retaining wall structure with or without dewatering seepage are carried out by using ABAQUS finite element analysis software.The results are compared with the field measurement results from various angles.The following main analysis results are obtained:(1)With the excavation of foundation pit,the lateral horizontal deformation of supporting structure tends to expand and the prominent position of deformation always appears between the excavation surface and the anchor cables of the upper road.The overall horizontal displacement and deformation of the supporting pile of foundation pit show an arc shape,and the maximum horizontal deformation is generally located in the position of 1/2-2/3 of the supporting pile.(2)Anchor cable support plays an important role in controlling the deformation of supporting piles.The horizontal displacement of the top of supporting piles can be effectively controlled by applying the first anchor cable to the crown beam position.In addition,the horizontal and vertical deformation of the top of supporting piles located at both ends of the supporting structure of foundation pit is smaller than that of the top of supporting piles located in the middle position because of the large restraint effect.(3)The application of anchor cable makes the stress redistribution of supporting piles more uniform.The stress increase of supporting piles is limited in the whole process.The anchor cable bears most of the load of soil acting on supporting piles.With the progress of various working conditions of foundation pit,the stress concentration area of supporting piles gradually movesdown.At the same time,it can be found that the stress distribution of crown beam and waist beam is more uniform as a whole,and there is no stress concentration and mutation regions.(4)With the progress of each working condition,the stress of the anchor cable varies obviously.Every excavation of the soil will increase the stress of the anchor cable,and the application of the lower anchor cable will distribute the load to the upper anchor cable,so when the lower anchor cable is applied,the stress of the upper anchor cable will decrease,and the stress of each anchor cable will increase first along the length of the anchor cable due to the existence of the rupture surface in the soil,later decreasing trend.(5)The existence of dewatering seepage will increase the internal force and deformation of retaining wall structure of deep foundation pit,which has an important influence on the evolution law of internal force and deformation of retaining wall structure.There are 57 papers,15 tables and 56 references.