【作者】 刘双菊；

【导师】 郑刚；

【作者基本信息】 天津大学 ， 岩土工程， 2008， 博士

【摘要】 作为快捷、安全、高效和优质的交通方式,高速铁路已成为许多国家旅客运输发展的共同趋势。然而,高速铁路对路基沉降特别是工后沉降也提出了更高更严格的要求。因此,本文对桩-板不同连接方式的沉降机理及其在路基中的应用进行了研究。本文所做的主要工作和研究结果如下:1.本文设计了预留净空桩基础及普通桩筏基础的群桩试验,采用给砂土染色及给桩进行标记,并连续照相的方法,深入研究了预留净空桩基础的沉降特性,并对两种基础就桩土相对滑移及桩端刺入进行了比较研究,最后给出了中桩轴力及侧摩阻力的变化情况,结论表明,预留净空桩基础,可使桩间土变形提前发生,加强桩土相互作用,减小桩土之间相对滑移,使桩、土相对于常规桩筏基础来说更趋于整体下沉。2.对京津城际轨道交通工程的前期现场测试数据进行了分析,对DK84+050断面及DK84+150断面进行了比较,并总结了两个断面的沉降-时间发展分布规律、沉降沿深度分布规律及桩、土荷载分担情况。3.采用室内三轴试验对京津城际轨道交通工程的土层参数进行了测定,采用大型通用有限元软件ABAQUS利用剑桥模型对其进行了模拟,并预测了工程投入使用20年后的沉降情况,进一步分析了两个断面的地面沉降发展情况、桩土沉降发展情况及孔压发展情况。4.在DK84+050断面模拟的基础上,研究了预留净空桩基础在路基中的应用,并与实际工程的模拟进行了对比分析,研究了地面沉降发展情况、桩土应力发展情况及孔压消散的发展。结论表明,预留净空桩基础可以有效的减小路基工后沉降。更多还原

【Abstract】 As a fast, safe, high-efficient and high-quality traffic form, the high-speed railway has become a common trend for many countries in development of passenger traffic. However, high-speed railway at the same places a more strict demand on the settlement of subgrade, especially post-construction settlement. Therefore, the settlement mechanism of different connection between pile and raft and its application in railway subgrade are researched in this paper. The major research work and achievements are as follows.1. A series of tests on conventional pile foundation and gapped pile foundation (with a gap between pile head and raft)were conducted. Through the analysis on continuous photos of colour sand layers and marked piles in the test, the settlement characteristic of gapped pile foundation was researched. Moreover, the penetration of pile toe and relative slip between pile and soil of the two kinds of foundations mentioned above were compared. Finally, the variation axial force and shaft friction of center pile was showed in this paper. The results show that gapped pile foundation can cause the soil among piles to deform in advance, enhance the interaction between soil and pile and reduction the relative slip between pile and soil and lead a more integral settlement of pile and soil of gapped pile foundation than that of conventional pile foundation.2. The in-situ monitoring data of the Beijing-Tianjin Rail Transport Project during early period was analyzed and the sections across DK84+050and DK84+150 were compared. Besides, the relation of settlement-time and settlement-depth and sharing of soil and pile were summarized.3. Through triaxial tests in laboratory the soil parameters of the project above were gained and the project was simulated by finite element software ABAQUS using modified Cambridge Model. The settlement at the time 20 year after the project in use was predicted. In addition, the development of the settlement of ground, pile and soil and pore pressure was analyzed.4. Based on the simulation of Section DK84+050, the application of gapped pile foundation in subgrade was researched and the comparison with practical project simulation was made. Furthermore, the development of the settlement of ground, the stress of soil and pile and dissipation of pore pressure was also studied. The conclusion is that the post-construction settlement of subgrade can be efficiently reduced by gapped pile foundation.更多还原