Study On The Technology Of Lateral Restraint Preloading And Deformation Analysis Of Highway Soft Foundation

With the implementation and popularization of high speed railway and highway construction in our country,many kinds of bad geology,such as soft soil,expansive soil and collapsible loess,are often encountered in engineering practice.The settlement deformation of highway soft soil foundation under load is divided into vertical settlement and lateral extrusion settlement.Lateral extrusion not only affects the total settlement of subgrade,but also affects the stability of surrounding buildings.In order to limit the lateral extrusion of soft soil under preloading and to reduce the adverse effect of surcharge preloading drainage consolidation on the surrounding environment,the paper puts forward the technology of lateral load preloading.Based on the finite difference analysis software and the scientific research project of my supervisor,combined with the practical project of the relevant literature,the research of this technology is carried out.And on the basis of rational hypothesis,we construct two approximate analytical formulas of soil under the condition of settlement with and without lateral restraint.The main conclusions are as follows:1.In order to limit the adverse effects of soft soil prepress and the reduction of groundwater level outside the preloading area to the surrounding environment,a new technology of preloading control is put forward.Based on the theory of soil mechanics,the contents and calculation methods of the concrete wall are put forward.2.Based on the FLAC^3D finite difference analysis software and the actual engineering,the consolidation model of the preloading and preloading under the unconfined condition is established.The simulation results of the unconfined preloading model are compared with the measured results of the relevant literatures,and the rationality and feasibility of the numerical simulation model of the pile preloading and drainage consolidation are verified.3.Based on the FLAC^3D finite difference analysis software,considering the influence of the stratified loading,the finite difference model of the preloading and drainage consolidation under the confinement condition is established.The influence of the depth andwidth of the confining position and the confined soil wall on the consolidation effect of the preloading and drainage is discussed.And the results show that the preloading control technology can effectively reduce the settlement of soft soil foundation and improve the consolidation rate at the early stage.When the consolidation rate is 80%,the time of stacking preloading limit control technology can be reduced by 10 days.The setting of the lateral limit has a significant effect on the preloading and settlement.When the lateral position is located at the edge of the stacking preload zone,the maximum settlement of the preloaded area can be reduced by 58.93% compared with the unconfined.The optimum lateral position is located at the edge of the stacking preload zone.4.On the basis of reasonable assumptions,the displacement function satisfying the displacement boundary condition is constructed.Based on the variational method in elastic mechanics,the variational equation of the confinement and unconfined preloading is established.The approximate analytical formula of the calculation of the lateral and unconfined preloading deformation is introduced and compiled by MATLAB software program.The theoretical results are compared with the simulation results,and the rationality and feasibility of the calculation method are verified.