Centrifugal Model Tests Of Deep Medium-Compression Soil

The consruction of passenger rail line is being carried out widly in our country,so it is significant to research the deformation characteristics of settlement of deep subsoil under passenger rail line and the characteristics of stress distribution in the foundation when it assunme the role of soft subgrade;especially early in the design,it is important to have accurant,scientific,reasonable calculations and predictions of deformation of foundation settlement for PDL's pre-construction and post-operation and maintenance. This work is to conduct centrifuge model of PDL'embankment in the above of deep silty clay,silty,completely decomposed granite foundation,and to discuss in the role of the flexible load, the relationship between time and settlement of entreated foundation, and to disscuss in the role of the flexible load, the additional sress in the in the foundation.Key findings are as follows:The design and model making methods of untreated foundation'section centrifuge model, dynamic compaction of foundation'section centrifuge model, cement mixing pile foundation'section centrifuge model are proposed.Through the analysis and comparison among the results of untreated, dynamic compaction and cement mixing pile,It can be found that dynamic compaction can reduce the amount of settlement of foundation durying the filling,and also reduce the amount of post-construction settlement correspondly at the same time;so effect of dynamic compaction is obvious.Although the embankment height of cement mixing pile foundation'section is slightly different from untreated foundation'section,It can be known from the result of the test,cenment mixing pile can fill most of the settlement to be completed during the construction period,can be effectively reduce post-constribution settlement,In terms of high-speed railway foundation that control post-construction settlement strictly,cement mixing pile is an effective reinforcement method.By means of simplification of Basal stress distribution model, the additional stress in the foundation was solved by boussinesq method,and according to layerwise summation method, the total settlement was calculate by using hyperbola's compression modulus from consolidation test.This total settlement is closer to another which was fitted with the result of test using three-paramater.So layerwise summation method can be one of the reference methods which are used to deduce total settlement in engineering design and construction...