【作者】 刘剑光；

【导师】 于志强；

【作者基本信息】 西南交通大学 ， 岩土工程， 2003， 硕士

【摘要】 软土在我国广泛分布，它抗剪强度低变形大，如果处理不当，地基会产生局部或整体剪切破坏。我国铁路和公路建设中，线路经常要穿过软土路段，为了保证上部结构的安全正常使用，对软土路基进行处理就显得尤为重要。目前处理软土路基的方法有很多种，粉喷桩是其中一种。本文结合宁启铁路工程的水泥粉体喷搅桩(简称粉喷桩)复合地基的现场施工及试验，对粉喷桩加固软土路基作了研究，具体研究内容包括以下几方面： 1．作者首先介绍了软土的成因和分布，软土的物理力学以及工程性质，阐明了软土加固处理的必要性及目前软土路基加固处理的方法。并从水泥颗粒与粘土颗粒之间的化学反应方面，对粉喷桩加固软土机理作了分析。 2．介绍了粉喷桩设计，即粉喷桩复合地基的承载力的设计计算，下卧层强度和复合地基变形验算，并对粉喷桩的设计思路作了归纳。 3．结合现场施工实际，对影响粉喷桩施工质量的因素作了分析，并对经常出现的质量问题作了探讨并提出了施工处理措施。 4．通过现场荷载试验和低应变测试，对粉喷桩加固效果作了分析。从试验结果来看粉喷桩加固软土路基加固效果很好，能满足上部结构对地基强度和变形的要求。 5．作者结合现场试验，对粉喷桩荷载传递机理和破坏模式作了探讨，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，并对影响桩土应力比的因素作了归纳总结。 6．最后，在现有的理论基础上，借助于静载试验，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，并根据宁启铁路工程实例取k值为1.1～1.2。更多还原

【Abstract】 Distributed widely in our country ,soft soil has low shear strength and large deformation .If soft soil was treated in mistake way,foundation would come into being local shear failure or general-shear failure. In railway and road engineering ,the line often crosses soft soil section .For ensuring the safety of superstructure ,it is important to improve soft soil roadbed. The technique of cement power-sprayed piles is one of improving soft-soil roadbed technology presently.Combining with the construction and field tests of Nanjing-qidong railway, some research of using cement power-sprayed piles to improve soft- soil roadbed was conducted and the research includes several aspects below:1.The authour first introduces the formation.distribution,physical mechancial behaviour and engineering characteristic of soft soil, and clarifies the necessity of improving soft-soil roadbed. Afterwards,the authour studies the mechanism of cement power-sprayed piles composite foundation from the chemical reaction between cement particle and soil grain.2.The design of cement power-sprayed is introduced in the thesis including composite foundation bearing capacity design,the checking computations of underlayer strength and composite foundation deformation.3.Combining with field constuction, the factors influencing the construction quality of cement power-sprayed piles are analyzed,and the often- occured quality defects are discussed.Then the author puts forward the constructive measure for coping with the quality defects.4. By field loading tests and small strain measurement,the result of improving soft soil with cement power-sprayed piles is alalyzed.The author believes that the result is good and composite foundation is able to meet the superstructure’s requirement for foundation strength and formation.5. Combining with field test,the author disputes load transfering mechanism and mode of failue about cement power-sprayed,and studies the relationship of n (the stress ratio of piles to soil) to load P .At last,the author summizes the factors to effect n.6.Using present theoretics, the author puts forward the theory of calculating the value of n by the modified value of modulus of compressibility A:.The value ofk is 1.1-1.2 in the engineering of nanjing-qidong railway.更多还原