The Plastics Drain Board Method Handing Soft-Soil Subgrade Of Freeway

Based on the monitoring task of special and key subgrade construction of the highway,which is from Bazhong to Nanchong, under embankment self-respect role,the article analyze and study settlement and stabiity of soft soil foundation processed by plastic drain plate. Combining with the site subgrade construction, plastic drain plate is equivalent to the sand well,which is equivalent to the sand wall later according to the equal of principle.Using the finite element program of PLAXIS,the plane strain finite element model of soft soil foundation processed by plastic drain plate is created,and subgrade construction process step is simulated.With the process of subgrade construction,the abreaction rule of excess pore pressure, the trendency of safety coefficient changing, the trendency of foundation settlement changing and horizontal displacement of slope toe changing are researched.Meanwhile, the principle of site subgrade monitoring,the process of installing of detection instrument and detection results are stated.The similarities and differences of site detection results and numerical simulation results are compared too,the reason for which is made clear. The mian conclusions of the article are as follows:(1) Using the finite element program of PL AXIS,the plane strain finite element model of soft soil foundation processed by plastic drain plate is created,and subgrade construction process step is simulated. From numerical simulation results, excess pore pressure indented change growth trend basically during construction of the subgrade,and it will drop during the construction gap.with the consolidation and settlement of the soft soil, excess pore pressure will wear off,the value of which will reach close to zero finally.(2)The settlement of foundation and horizontal displacements of slope toe s positively relate to the subgrade construction speed,and the safety coefficient presents negative correlation to the subgrade construction speed.(3)Site detection results prove subgrade construction speed influence foundation settlement rate and horizontal displacement rate obviously,foundation settlement and horizontal displacement increase with the height increase of embankment construction significantly. Slope toe arise horizontal lateral displacement away from subgrade center gradually with the process of embankment construction.If the surface soft soil is thicker, horizontal lateral displacement of 2.0m place under the original surface will achieve maximum. (4)During the process of the embankment construction, the changing trendency of foundation settlement and horizontal displacement of numerical simulation results consistents with that of the site detection results. According to the comparison with site detection results,the proposed nonlinear finite element method combining shear strength reduction can effectively deal with the topic of deformation and stability properties of soft soil under embankment self-respect role.