【作者】 王建华；

【导师】 张勤；

【作者基本信息】 河海大学 ， 地质工程， 2007， 硕士

【摘要】 软土在我国分布广泛、抗剪强度低、变形大，若处理不当，地基会产生局部或整体剪切破坏。为了保证道路的安全运行，对软土路基进行处理就显得尤为重要。本文以广州南沙经济开发区南珠高速公路珠江入海口段工程为背景，对其采用的粉喷桩有效桩长进行以下几方面的探讨：阐述了软土加固处理的必要性及软土路基加固的方法，并从水泥颗粒与粘土颗粒之间的化学反应入手，对粉喷桩加固机理作了简要的分析；通过Mindlin方程确定了水泥搅拌桩单桩的有效桩长，并分析了桩土模量比、置换率、桩土应力比、泊松比、桩直径对水泥搅拌桩有效桩长的关系；采用Adina软件对复合地基进行模拟，结果表明，上述因素除泊松比对有效桩长的影响不明显外，其余因素均有较大的影响；通过现场载荷试验和低应变测试，对粉喷桩的桩土应力比n与荷载水平P的关系进行了研究，对影响桩土应力比的因素作了归纳总结，提出了采用地基土压缩模量的k值修正计算桩土应力比n值的方法，为工程建设提供了有力的理论支持。更多还原

【Abstract】 Soft soil, distributed widely in our country, has the characteristics of low shearing strength, large deformation. If soft soil was treated in mistaken way, foundation would come into being local shear failure or whole shear failure. It is a virtual importance for soft-soil foundation to deal with, in order to guarantee freeway to run safely. The paper discusses some aspects below to the effective pile-length of cement power-sprayed piles in the background of the engineering of Nan-zhu highway of Nan-sha economic development area in Guangzhou at the entrance of zhujiang.In the paper the main work is carried out about the above. Base on the research progress of cement power-sprayed piles, which is used to deal with softy foundation of highway, the chemical and mechanical mechanism is explored and clarifies the necessity of improving soft-soil foundation. Afterwards, the author studies the mechanism of cement power-sprayed piles composite foundation from the chemical reaction between cement particle and soil grain. First effective length of cement-mixed single pile is computed by elastic theory - Mindlin Equation, then the relations between effective length of single pile and the modulus ratio of pile to soil, substitution ratio, the stress ratio of pile to soil, poisson’s ratio, the diameter of pile are analyzed. At last its numerical simulation is conducted by large and common finite element software named Adina. It’s results show that the effect of poisson’s ratio on effective pile length is unobvious and the effect of other’s factors on effective pile length is very obvious. In particular, by field loading tests and small strain measurement, the author studies the relationship of n (the stress ratio of piles to soil) to load p and summarizes the factors to effect n and puts forward the theory of calculating the value of n by the modified value of modulus of compressibility k, witch affords available method for engineering construction.更多还原