Research On Settlement Characteristics Of Unsaturated Soil Cement Mixing Pile Foundation Reinforcement

The smoothness and safety operation of dedicated passenger line on the premise that foundation which has special geological conditions has been reasonably、economically treated. That is to say, the foundation treatment design is more important. This paper takes unsaturated powder soil and silty clay in Jiaoji dedicated passenger line as research object. First, applying indoors experiment、field in-situ tests and field settlement monitoring tests to research the regularities of settlement, and to summarize the settlement deformation Characteristics of Cement mixing pile reinforcement unsaturated foundation soil. Then, predict the deformation trends, and control the settlement after Construction. Last, evaluate the reinforcement effect of unsaturated soil foundation using cement mixing pile method. The main studies in the paper are as follows:1、 Through four field in-situ tests:plate loading tes、static cone penetration test、 standard penetration test and lateral pressure test,to evaluate the bearing capacity and deformation characteristics.2、Through long-term observation and research the settlement deformation stability change and development regularity of Cement mixing pile reinforcement unsaturated foundation soil, master process and trend of the settlement deformation of the unsaturated soil foundation in construction, discuss the regularities of foundation settlement deformation, meanwhile, provide experiment basis for theoretical study, detect the reinforcement effect of the designed foundation, verify the correctness of designed theory, plan construction control standards, guide design and construction.3、Obtain stress transferring rules which fit with Cement mixing pile reinforcement unsaturated foundation soil foundation. Apply theoretical formula to calculate the value of foundation settlement, and apply empirical formula to predict the foundation settlement of Cement mixing pile reinforcement unsaturated foundation soil. Provide foundation calculation design of unsaturated soil with basis, through theoretical analysis and the regularities summary of foundation settlement deformation and stress transferring.4、Analyze consolidation squeezing properties of unsaturated soil on the basis of unsaturated soil consolidation test. For unsaturated soil whose matrix suction is lesser than intake, settlement calculation of consolidated unsaturated soil can apply saturated soil method because of the soil structural similarity between unsaturated soil and saturated soil; for unsaturated soil whose saturation is higher than remaining saturation, through the relation between saturation and matrix suction to modify consolidation coefficient combining with the liquid volume change law in consolidation. And on this basis, comparative analysis of cement mixing piles reinforced unsaturated soil foundation with the change of time consolidation degree relationship.