Study On Characteristics Of Expansive Soil And Finite Element Analysis Of Single Pile During Expansion And Contraction

Since the reform and opening up,especially in the last ten years,China's national economy has developed rapidly,and the country has gradually increased the intensity of infrastructure construction.The rapid rise of the central region has further promoted the process of domestic infrastructure construction.Many inland cities have rapidly developed along with the “Belt and Road” national opening-up strategic economy,and the urbanization process has continued to accelerate.Therefore,the construction of roads,bridges,and railways in expansive soil areas is becoming more and more complicated,and the geological conditions are also becoming more and more complicated.Expansive soil's expansion,contraction,fissure and over-consolidation have caused many problems in engineering construction.Therefore,it is of great engineering significance to conduct research on the characteristics of expansive soils and the working characteristics of single piles in expansive soils.This article takes a project in Handan expansive soil area as the research object,conducts field surveys,conducts a lot of field and indoor tests,and studies the relevant characteristics of expansive soils.Based on ABAQUS finite element software and physical indexes of Handan expansive soils,expansive soils are established-Single pile expansion and contraction model,which simulates and analyzes the working behavior of single pile in expansive soil,evaluates the influence of pile soil displacement and negative friction resistance on engineering safety in expansive soil,and provides a reference for the design and construction of pile foundation in expansive soil.The main research contents are as follows:(1)Through a geological survey of a project in Handan expansive soil area,a large number of field and indoor tests were conducted to analyze and study the basic physical and mechanical properties of the soil layer in the area,and the analysis of the bearing capacity and expansibility of the foundation was made.Evaluation.And through a series of laboratory tests,the swelling and shrinking characteristics,swelling force characteristics and strength characteristics of the expansive soil were studied,and the changes of the basic characteristics of the expansive soil were analyzed.(2)Based on ABAQUS finite element software,a finite element model of a single pile in expansive soil is established.The single pile during the expansion and contraction of expansive soil is simulated and analyzed.By changing the parameters,the variation characteristics of the working behavior of a single pile under different expansion potentials,different pile top loads,and different pile lengths are compared and analyzed.(3)The pile-soil displacement of the single pile during the expansion of the expansive soil and the negative friction resistance during the shrinkage were analyzed.The displacements of piles and soils,the variation of axial force and negative friction resistance,and the effects on the bearing capacity of pile foundations were compared under different swelling potentials,different pile top loads and different pile lengths.