Study On The Influence Of Prewetting Compaction And Soaking After Construction On Pile Foundation Vertical Bearing Capacity In Large Thickness Collapsible Loess Foundation

With the West Development in our country making progress step by step, the numberand scale of the infrastructure in the northwest region are increasing and expanding, makingmore and more buildings need to be built in the large thickness collapsible loessfoundation. Forin recent years the global climate conditions changing, the rainfall in thewestern region increaseas compared to the past years. In order to avoid the foundationafter soaking collapsible causestructural damage, to ensure that the special foundationengineering structures are safe andaffordable, how to eliminate the collapsibility of collapsible loess foundation duringconstruction process, is the important issues to be re-solved for the engineering and technicalworkers in design and construction phases.In order to eliminate collapsibility of the collapsible loess foundation, you need todeparture from the collapsibility mechanism, combined with the collapsibility necessaryconditions to propose specific approach and engineering measures.For large thickness collapsible loess foundation, taking the technical and economicaspects into account, the method of prewetting as well as compaction should be takento eliminate the collapsibility of the large thickness collapsible loess foundation, in order to improve the bearing capacity of pile foundation in this kind foundation. In this paper,to solve the problem some works as following are done and corresponding conclusionsare summarized:(1) Base on a lot of literature reading, to acquire knowdge about the methods andengineering measures which are commonly used in collapsible loess foundation treatm-ent, especially take a analysis for the variation laws of the mechanical properties ofloess for pre-wet as well as compaction, and flooding after construction;(2) For large thickness collapsible loess ground which are less affected by the cha-nge of groundwater level, combined with the data of test pitimmersion, to analyse thefactors that affect the foundation flooding process, propose the way of prewetting proce-ssing method to eliminate the effection of foundation by immersion of surface runoff; Forlarge thickness collapsible loess foundation treatment, engineering practice shows that using hierarchical humidification collapsibility is a very effective way to eliminate the collapsibility.(3) Combined to friction pile foundation engineering instance and using ANSYSfinite element software, take a analysis of pile vertical bearing performance in the casesof prewetting and soaking after construction;(4) For existing pile foundation in collapsible loess ground, take finite element sim-ulation analysis to explore the variation laws of the vertical bearing performance of pile foundation under different pile design parameters after soaking;(5) Through the analysis comparison of pre-wet before construction as well as com-paction and flooding after construction in pile foundation construction, the result showsthat prewetting before construction as well as compaction can significantly improve thevertical bearing capacity of pile foundation, but flooding after construction will reducethe bearing capacity reserve of pile foundation.