【作者】 李雪刚；

【导师】 徐日庆；

【作者基本信息】 浙江大学 ， 岩土工程， 2013， 博士

【摘要】 杭州地区海相沉积软土具有天然含水量高,压缩性高,承载力低,有机质含量高等工程特性,在对其进行固化处理时,由于高有机质含量的存在,水泥固化效果并不理想,因此有必要选择适宜的添加剂来改善水泥固化的效果,从而配制一种高效复合固化剂,并且开发针对各种不同有机质含量软土的固化剂产品；为了将所开发的固化剂更好的应用于工程实际,需要对固化土的强度形成规律和固化土渗透性等物理力学特性进行研究；另外,研究适宜固化土的本构模型是对固化土进行数值模拟的基础。为此,本文主要开展如下工作：(1)从软土的成因分布,化学,物理力学性质,应力应变关系,结构性等方面对杭州地区第四纪全新统海相沉积软土进行系统的研究,从而科学评价杭州软土的工程特性。(2)针对杭州地区海相软土高有机质含量和高含水量的特性,在添加水泥的基础上,从选择合适的矿物填料,减薄土壤双电层的厚度,提高土壤PH值,增强早期强度,调节水泥离子和黏土颗粒的活性等五个方面选定生石膏,生石灰,碳酸钠,FDN,水玻璃,三乙醇胺等六种添加剂来改善有机质软土的固化,开发性能优越的高效复合固化剂。(3)利用响应面法来对添加剂进行优选和配方研究,并考察各影响因子的交互作用规律。确定不同有机质含量的最优固化剂掺量和水泥掺量,使得所开发的固化剂产品能适应于各种不同有机质含量的软土。(4)采用水泥及固化剂GX08对有机质土进行固化,分析各种因素对强度的影响规律,在此基础上,建立同时考虑固化土中有机质含量、水泥掺量、固化剂掺量和龄期影响的固化土综合强度预测模型。(5)分析固化土的重度和含水量等指标受不同配比和龄期影响的变化规律。在对复合固化剂作用下固化土渗透性的变化规律进行研究的基础上,建立复合固化土的渗透系数预测方法。(6)考虑有机质含量,固化剂掺量和水泥掺量三个因素影响下的损伤本构模型参数的变化规律,以及损伤变量的演化规律,最终建立综合考虑有机质含量,固化剂掺量和水泥掺量影响的固化土弹塑性损伤模型。更多还原

【Abstract】 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.更多还原