【作者】 李西斌；

【导师】 谢康和；

【作者基本信息】 浙江大学 ， 岩土工程， 2005， 博士

【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、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。更多还原

【Abstract】 It is well known that rheological property is one of the important 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 parameters, 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 studied 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 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 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 boundaries and rheological parameters on the consolidation are discussed3. 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 testing curves, including the ones for pore water pressure dissipation, are prepared to discover the behavior of rheological consoiidation 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 coefficient 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 ofXiao-shan soft soil is analyzed, and parameters of rheological 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 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, non-linear rheological model is more suitable to Xiao-shan soft soil更多还原