Application Of Plastic Drainage Board In Soft Foundation Treatment Of Xianhai Section Of National Highway 108 Application Research

The key to the treatment of soft soil subgrade is to correctly understand the characteristics of soft soil and its harmfulness,and to choose a reasonable treatment method of soft soil by referring to the previous engineering experience and combining with the actual conditions,so that the subgrade can maintain sufficient strength and stability.In this paper,the settlement calculation results and deformation characteristics of Mianyang City Transit section(Xianhai Section)of National Highway Line 108 are studied by field investigation and numerical simulation.The main research contents and achievements are as follows:(1)By combining on-site investigation,on-site testing,and laboratory testing,the terrain and hydrological characteristics of the site,the on-site characteristics of soft foundation,and soil layer parameters were obtained,and corresponding treatment measures were proposed based on different soft soil characteristics.(2)Based on the characteristics of the project,a typical soft soil roadbed section is selected for plastic drainage board treatment,and theoretical calculations and analysis are conducted on the consolidation settlement and stability of this section.(3)Calculate the settlement of the clay layer of 10 holes in this section,analyze the influence of soft soil thickness on the settlement and get the settlement law.(4)PLAXIS software was used to conduct numerical simulation of the subgrade before and after the foundation was treated with plastic drainage board.By analyzing the nephogram of excess pore pressure and final vertical displacement,it is proved that the plastic draining plate can accelerate the consolidation of soft soil.(5)Through the control variables,the influence of the depth,spacing and loading of the drainage plate on the subgrade is further simulated and studied.The consolidation degrees of single load and graded load at different spacing were calculated respectively.The depth of6 m,7m,8m,9m and 10 m were set respectively for modeling calculation using PLAXIS,and the cloud image of excess pore pressure and final vertical displacement were analyzed.(6)Settlement and horizontal displacement monitoring points are set in soft soil subgrade,high embankment,deep cut and bridge head embankment of the whole section.The research results are summarized to provide reference datas and experiences for similar projects in the future.