Study On The Settlement Prediction Of Saturated Soft Clay By Plastic Drain Board Preloading

The saturated soft clay is widely distributed in coastal areas,with high water content,large pore ratio,low permeability and high compressibility.Under the load,the soft soil foundation will cause excessive settlement and difference in settlement,which has been a major problem to be solved during the construction process.Therefore,a reasonable settlement prediction method should be used to predict the settlement of soft soil foundation.Based on the field monitoring data,the Asaoka inversion consolidation coefficient method is improved in the case of the horizontal consolidation coefficient and the well resistance and the smear effect,and the settlement of the actual project is predicted,calculated and analyzed by the improved method,the Asaoka method,the hyperbola method and the three point method.The main research work is made in the following aspects:(1)Taking the soft soil foundation treatment of the first phase project of a certain silt coating in Zhoushan base as the research background,this article carry out the monitoring analysis of ground settlement,stratified settlement and pore water pressure during actual construction.Studying on the deformation characteristics of the soft soil foundation under the preloading of the plastic drain board,we find that the silt soil layer is the main soil layer of the deformation of consolidation,and the deformation accounts for more than 90% of the total deformation.(2)Based on the analysis of the measured settlement data,the post construction settlement is predicted by Asaoka method,hyperbola method,three point method and improved Asaoka inversion consolidation coefficient method.The results of comparing and analyzing the differences among the four methods show that,the Asaoka method and the three point method have a higher requirement for the time interval of prediction settlement point,and the predicted post settlement values are negative.;Although the predicted settlement values are positive by the hyperbolic method,the parameters of consolidation and the effect of the well resistance smearing can not be considered in the calculation model.While the settlement value calculated by the improved Asaoka inversion consolidation coefficient method is positive,and considers the consolidation parameters and the effect of well resistance smearing.It is more consistent withreality.(3)This article also establishes the two-dimensional finite element model by the finite element software Midas GTS,and it simulates the construction conditions of the preloading treatment for soft soil foundation with plastic drain board.It is found that the change law of the settlement and pore water pressure with time is similar to the actual change law,but there is a slight difference in numerical value due to the complexity of actual engineering.