Theoretical Study On Stabilization Of Marine Soft Clay In Hangzhou

When Hangzhou marine soft clay with high natural water content, high compressibility, and low bearing capacity, are cemented, the stabilization effect of single-doped cement is not satisfactory, due to the adverse influence of high organic matter content on soil cementation. As a consequence, extra admixtures are added to accelerate the reactions of cement and improve the stabilization effect in the actual projects. The purpose of this study is to develop a kind of composite curing agent which is high efficient to soft soil stabilization, and to develop series products of curing agent used for stabilizing different soft soil with various organic matter contents. In order to apply the developed curing agent to the the actual engineering better, it is necessary to research the physical and mechanical characteristics of the stabilized soil. Moreover, an appropriate constitutive model on stabilized soil is the basis of the numerical simulation. Based on the above points, the dissertation mainly carried out the following work:(1) The distribution, the chemical and physicals properties and the stress-strain relationship of the marine soft soil in Hangzhou were comprehensively researched to scientifically evauate the engineering properties of soft soil in Hangzhou.(2) For Hangzhou marine soft soil possessing high organic matter content and high water content, gypsum, calcium oxide, sodium carbonate, FDN, sodium silicate, and triethanolamine were selected as six kinds of additives to improve the stabilization of organic matter soil. It is based on the consideeriation of the following five aspects:the choice of appropriate mineral filler, reduction of the thickness of soil electrical double layer, increase of the PH value of soil, enhancement of the early strength, and improvement of the activity between cement ion and clay particle.(3) Response surface methodology was used to optimize the mixture ratio of the additives and analyze the interaction effect among the factors. The optimal curing agent content and cement content were determined so that the developed curing agents can be applied to soft soils with various organic matter contents. (4) Based on the quantification of various factors on the influence of strength, a strength model was proposed, which has incorporated the positive effect of curing time, cement and stabilizing agent content, and the adverse effect of organic matter on the strength of stabilized soil.(5) Based on the analysis of permeability variation of stabilized soil with different curing agents, a simple method was established to predict the coefficient of permeability of stabilized soil.(6) Based on the analysis of the effect of organic matter, cement and curing agent on the parameters of damage constitutive model, an elastic and plastic damage model of stabilized soil was proposed, which has considered the effect of organic matter content, cement content and curing agent content on the stabilized soil.