饱和重塑黏性土流变固结与卸荷回弹特性试验研究

发布时间：2018-05-28 03:13

本文选题：土力学 + 饱和黏性土　；参考：《郑州大学》2017年硕士论文

【摘要】：饱和黏性土的流变固结及卸荷回弹特性对实际工程具有重要意义,本文利用改进的渗透-固结联合试验系统对河南信阳某地饱和黏性重塑土试样开展了变水头渗流、流变固结、竖向卸荷回弹等一系列试验研究,主要成果如下:1、首先分别推导出了变水头渗透试验满足Darcy渗流模型、幂指数渗流模型、Hansbo渗流模型的水头-时间(h-t)表达式,并对三参数渗流模型建议了一种新的数值拟合方法。变水头渗透试验的拟合结果表明,试验用土在不同孔隙比下的的渗流明显存在着对Darcy定律的偏离,且试验数据更适宜用幂指数渗流模型和Hansbo渗流模型来拟合。2、一维流变固结试验表明,试验用土的流变现象明显,在土体变形分析中不可忽略,且主次固结过程有明显的耦合现象。单面排水一维流变固结试验表明,加载后不排水面孔压不会立即上升到最大值,存在明显的滞后现象,且传统的Casagrande法和孔压消散法确定主次固结分界时间明显不一致。另外,孔隙比、超固结比、排水条件、试样高度等条件对其流变固结特性影响明显。3、竖向卸荷回弹试验表明,卸荷回弹是流变固结和卸荷回弹共同作用的过程,卸荷回弹稳定较流变固结所需的时间更加漫长。对卸荷回弹过程进行分析时可将其看做是流变固结的逆形式,并可以将卸荷回弹过程划分为主回弹阶段和次回弹阶段。竖向卸荷回弹特性的主要影响因素包括:卸荷比R、最大固结应力pc、卸荷速率等,卸荷比R为最主要影响因素,且存在临界卸荷比。
[Abstract]:The rheological consolidation and unloading resilience characteristics of saturated clay are of great significance to practical engineering. In this paper, the modified osmotic and consolidation test system is used to carry out the rheological consolidation of saturated clay remolded soil samples in Xinyang, Henan Province. A series of experimental studies, such as vertical unloading springback and so on, are presented. The main results are as follows: 1. Firstly, the water head-time h-t expression of the Darcy seepage model and the power exponent percolation model are derived respectively. A new numerical fitting method is proposed for the three-parameter seepage model. The fitting results of the permeability test show that the seepage of soil with different void ratios is obviously deviated from Darcy's law. The experimental data are more suitable to fit with power exponent seepage model and Hansbo seepage model. One-dimensional rheological consolidation test shows that the rheological phenomenon of soil used in the test is obvious and can not be ignored in the analysis of soil deformation. And the main and secondary consolidation process has obvious coupling phenomenon. One-dimensional rheological consolidation tests show that the undrained face pressure does not rise to the maximum value immediately after loading, and there is obvious lag phenomenon, and the traditional Casagrande method and pore pressure dissipation method to determine the primary and secondary consolidation boundary time is obviously inconsistent. In addition, the porosity ratio, over-consolidation ratio, drainage condition and specimen height have obvious effects on the rheological consolidation characteristics. The vertical unloading springback test shows that unloading springback is the process of rheological consolidation and unloading rebound. Unloading springback stability takes longer than rheological consolidation. The unloading springback process can be regarded as the inverse form of rheological consolidation and can be divided into the main springback stage and the secondary springback stage. The main influencing factors of vertical unloading resilience include unloading ratio (R), maximum consolidation stress (PC), unloading rate and so on. Unloading ratio R is the most important factor, and the critical unloading ratio exists.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU41

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