软土流变固结理论与试验研究

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1、 博博 士士 学学 位位 论论 文文 论文题目论文题目 软土流变固结理论与试验研究软土流变固结理论与试验研究 作者姓名作者姓名 指导教师指导教师 谢康和谢康和 教授教授 学科学科(专业专业) 岩岩 土土 工工 程程 所在学院所在学院 建筑工程学院建筑工程学院 提交日期提交日期 二零零五年五月二零零五年五月 李李 西西 斌斌 浙江大学申请博士学位论文浙江大学申请博士学位论文 软土流变固结理论与试验研究软土流变固结理论与试验研究 作者姓名：作者姓名： 李西斌李西斌 学科专业：学科专业： 岩土工程岩土工程 指导教师：指导教师： 谢康和谢康和 教授教授 浙江大学岩土工程研究所浙江大学岩土工程研究所 2

2、005 年年 5 月月 THEORETICAL AND EXPERIMENTAL STUDIES ON RHEOLOGICAL CONSOLIDATION OF SOFT SOIL by LI Xi-bin A Dissertation Submitted to Zhejiang University in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF ENGNEERING Major Subject: Geotechnical Engineering Advisor: Professor XIE Kan

3、g-he Institute of Geotechnical Engineering Zhejiang University, Hangzhou, China May 2005 摘 要 软土流变固结理论与试验研究 软土流变固结理论与试验研究 摘 要摘 要 流变性是软土的重要特性之一。历经 60 余年的发展，软土流变固结理论已得到很 大的提升，但关于理论的进一步完善、流变模型及其参数的确定等问题仍然是困惑、棘 手的未解难题。本文从理论和试验两个方面出发，对饱和软土的一维流变固结问题进行 了较细致深入的研究，以完善软土流变固结理论，得到确定流变模型参数的可行方法， 促进流变理论的实际应用。主要工作

4、包括： 1. 基于四元件线性流变模型，求得了受单级加载、两步加载、循环荷载作用的软 土一维流变固结解析解，并对各种荷载形式下的解进行了归纳总结。利用所得解分析了 变荷载作用下的软土一维流变固结性状。结果表明，荷载形式和流变模型参数的变化均 对固结过程有显著影响。 2. 基于三元件流变模型，利用叠加原理，得到了双面半透水边界下受常见循环荷 载作用的软土一维流变固结解析解， 并由此对具有双面半透水边界的软土层的一维流变 固结性状进行了研究，分析了透水条件、模型参数对固结过程的不同影响。 3. 详细介绍了 GDS 先进固结试验系统和试验步骤， 并利用该系统对萧山软土进行 了常规分级加载固结与渗透试验

5、、分级加载流变固结与渗透试验、压缩回弹再压缩 流变固结与渗透试验，绘制了大量包括孔压消散曲线在内的试验结果曲线，并进行了分 析总结。试验结果表明，萧山软粘土具有明显的非线性和流变特性，超固结比对次固结 系数有显著的影响。 4. 提出了一种精度高、应用方便的根据试验数据确定线性流变模型参数的非线性 拟合方法，编制了相应的自定义函数；利用该拟合方法对萧山软土一维流变固结试验数 据进行了拟合，得到了三元件和四元件流变模型的参数，分析了其变化规律，并根据所 得参数，结合解析理论对试样的沉降和孔压计算值与试验实测值进行了对比。 5. 确定了萧山软土的非线性流变模型参数，根据得到的参数利用现有的非线性流

6、变固结半解析理论进行了计算，并将计算结果与实测值进行了对比。结果表明，理论计 算所得的沉降和孔压与试验实测值基本相符；与线性流变模型相比，非线性流变模型更 适合于萧山软土。 关键词：关键词：萧山软土；流变；固结理论；循环荷载；半透水边界；GDS 先进固结试验系统； 试验研究；参数确定 i Abstract THEORETICAL AND EXPERIMENTAL STUDIES ON RHEOLOGICAL CONSOLIDATION OF SOFT SOIL ABSTRACT It is well known that rheological property is one of the i

7、mportant properties of soft soil. After the development of more than 60 years, the rheological consolidation theory have been greatly enhanced. However, about the further improvement of rheological consolidation theory, and rheological model of soft soil, as well as the determination of its paramete

8、rs, etc., there are still many to be done. In order to make rheological consolidation theory more perfect, and find a feasible way for determining rheological parameters, as well as to promote the practical application of rheological consolidation theory, rheological consolidation of soft soil is st

9、udied carefully and in-depth from theoretically and experimental aspects in this dissertation. The main original work includes: 1. Based on the linear rheological model of four units, analytical solutions are obtained and summarized for one-dimensional consolidation of soft soil under several types

10、of time dependent loading, and the rheological consolidation behavior of soft soil is analyzed. It is indicated that the variations of both loading type and parameters of rheological model have great influence on the consolidation process. 2. Based on the linear rheological model of three units, the

11、 analytical solution for one-dimensional consolidation of soft soil with two impeded boundaries under conventional cyclic loading is developed using integral method. The relevant rheological consolidation behavior of soil is investigated by using the solution and the different influences of impeded

12、boundaries and rheological parameters on the consolidation are discussed 3. GDS Advanced Consolidation Test System and the corresponding experimental steps are introduced in detail, and a variety sets of rheological consolidation tests with Xiao-shan soft soil are conducted on the test system. Many

13、testing curves, including the ones for pore water pressure dissipation, are prepared to discover the behavior of rheological consolidation of Xiao-shan sof soil. It is indicated that rheological characteristic of Xiao-shan soft soil is remarkable, and the over-consolidated ratio affects the coeffici

14、ent of secondary consolidation significantly. 4. A new convenient nonlinear curve fitting method with high accuracy is developed for determining rheological parameters from teat data. By using this method, the testing results of ii Abstract Xiao-shan soft soil is analyzed, and parameters of rheologi

15、cal model of three units and of four units are respectively obtained and the variation law of these parameters investigated. Comparisons are then made between the results obtained by the developed analytical consolidation theory using these parameters and the ones obtained directly from test. 5. The

16、 parameters of non-linear rheological consolidation model are obtained for Xiao-shan soft soil based on the test data. Using these parameters, theoretical settlement and pore water pressure are obtained by using available semi-analytical method for nonlinear rheological consolidation analysis and compared with the ones from tests. It is shown that theoretical results are in fairly good agreements with that of tests, and that comparing to liner rheological model,