导　　师： 魏静

学科专业： 082301

授予学位： 硕士

作　　者： ;

机构地区： 北京交通大学

摘　　要： 高速铁路路基作为线路轨下基础的重要部分,其变形和稳定性对列车的正常运行有至关重要的影响。涵路过渡段路基作为不同于一般路基的特殊构造物,其沉降特点和桩土应力情况也会不同于一般路基,因此研究过渡段位置的路基沉降和桩土应力特性,对合理分配桩土承担荷载以及有效控制工后沉降,对今后高速铁路过渡段路基的设计都有着比较重要的意义。 本文基于津秦客运专线某涵路过渡段沉降控制技术研究项目,首先对国内外桩网复合地基和路桥/(涵/)过渡段沉降特点等现有的研究成果进行分析总结,然后结合津秦客运专线的现场试验开展具体的研究工作,主要包括以下部分： /(1/)结合试验监测数据,对过渡段位置桩网复合地基的沉降特性进行研究,分析地基沉降随时间变化的特点以及在横断面和纵断面上的变化规律,总结过渡段上复合地基沉降特性。 /(2/)对土工格栅的变形情况进行分析,验证土拱效应的存在及其影响。 /(3/)选用合适的沉降预测方法对地基工后沉降值进行预测评估,确定沉降值是否满足规范要求和施工要求。 /(4/)结合土压力测试数据,对基底桩土应力的特点进行研究,详细分析桩土应力值随时间以及路基加载的变化特点,研究同一横断面位置桩土应力值的分布规律。分析桩土应力比随路基填筑的变化特点以及不同位置的桩土应力比对比情况。通过对基底50cm垫层之上的土应力情况进行分析,明确CFG桩在桩网复合地基承载中的重要作用。 /(5/)用有限元数值分析方法对实际工况进行模拟,对比数值模拟结果和实测数据,并对复合地基不同桩间距、不同桩长、不同垫层厚度时的沉降和桩土应力比进行比较分析,通过控制沉降值优化CFG桩网复合地基设计方案。 本文从理论分析、现场试验、数值分析模拟不同角度研究了过渡段桩网复合地基的沉降和桩土应力特性,分析结果对实际工程的施工和类似的工程设计有一定的参考意义。 The subgrade is an important part of the sub-rail base in a route, the deformation and stability of which has critical influences on the normal operation of trains. As a special structure,the settlement characteristics and pile-soil stress of the subgrade in road-culvert transition are different from those of the general subgrade. So the studies of the subgrade settlement and pile-soil stress in the transition section not only have important effects on the reasonable distribution of loads imposed on piles and soil, but also have important meaning to the effective control of post-construction settlement. The study can guide the design and research of the composite foundation in the transition sections of high-speed railway. This article is based on the study of settlement control technology in a transition section of Tianjin-Qinhuangdao passenger line.Firstly the existing results of pile-net composite foundation and settlement characteristics of the road-bridge transition section or road-culvert transition section were analyzed,then the research work combined with the engineering practice of Tianjin-Qinhuangdao Passenger Line were carried out.lt mainly consists of the following components: /(1/)Combining with the test data,the settlement characteristics of pile-net composite foundation in transition section were studyed,the characteristic of settlement change with time and the change rule of settlement in transverse and longitudinal sections was analyzed.Then the settlement characteristic of composite foundation in transition section was summarized. /(2/)The existence and effects of soil-arch effect were verified by analyzing the deformation of geogrid. /(3/)To predict the post-construction settlement and the final settlement by using appropriate methods, then determining whether the settlement value meets the standard and construction requirement. /(4/)To study the pile-soil stress of the composite foundation and analyze the variation of pile-soil stress value with time and loads by combining the test data.The variation of pile-soil stress of the same transverse section is regular.Then to study the variation of pile-soil stress ratio with the subgrade construction and compare the pile-soil stress ratio in different positions. At last,to confirm the importance of CFG piles in the pile-net composite foundation by nalyzing the soil stress in the areas of pad50centimeters above the subgrade /(5/)Using the method of finite-element analysis to simulate actual conditions and contrasting the results of numerical simulation with test data. The effects of pile spacing,pile length and. cushion thickness to settlement were analyzed. Finally the optimization design of CFG pile-net composite foundation by controlling settlement values was carried out. This article studies the settlement characteristic and the pile-soil stress of the pile-net composite foundation in the transition section through theoretical analysis, numerical simulation,field tests.The results have referential meaning on the construction and similar engineering design of actual projects.

关 键 词： 高速铁路 过渡段 复合地基 沉降 预测 桩土应力 优化设计

分 类 号： [U213.1]

领　　域： [交通运输工程]