非饱和土坡坡面降雨非正交入渗试验研究与数值分析

发布时间：2019-04-26 10:25

【摘要】：非饱和土坡在降雨入渗下的稳定性研究需要确定土体含水率,因此对降雨入渗的规律性及边界条件的研究具有重要的科学意义和实用价值。目前非饱和土坡坡面降雨入渗规律性及机理研究仍不完善,采用的正交边界条件存在缺陷。正交入渗边界对于不同性质的土采用相同的边界处理方法,对于边界条件转化的判别机制不符合非正交入渗实际,导致坡面土体的入渗计算的精度难以保证。在降雨入渗过程中,现有的坡面土体的入渗能力的确定方法具有缺陷,与实际的非正交入渗理论差异较大。为了研究非饱和土坡在降雨入渗条件下的入渗规律,探索符合实际的非正交入渗边界条件,本文进行了人工模拟降雨入渗试验,并针对非饱和土坡降雨入渗试验进行数值模拟。研究内容主要分为以下几个方面:(1)在原有室内模拟人工降雨装置的基础上进行改进,进而满足本文试验的要求;(2)对粉质粘土进行室内降雨入渗试验研究及入渗数值模拟,探讨雨强、坡角及孔隙比对降雨入渗规律的影响;(3)设计了室外大型降雨试验装置,并进行非饱和砂土室外坡面降雨入渗试验。对室内和室外非饱和土坡降雨入渗试验进行重点研究,分析得到非饱和粉质粘土和砂土坡面的降雨入渗规律。将试验结果与采用正交入渗边界的数值模拟结果相比较,证明了目前按正交理论处理的入渗边界条件存在的错误之处。非饱和土坡坡面降雨入渗的试验研究表明,对于渗透能力弱的粉质粘土,坡角和雨强的变化对降雨入渗的规律具有显著的影响,而数值模拟中难以反应出其对入渗率的显著影响;对于渗透能力较强的砂土,雨强与饱和渗透系数的相对大小不能作为坡面土体在降雨入渗过程中是否会饱和的判别条件。
[Abstract]:The study on the stability of unsaturated soil slope under rainfall infiltration needs to determine the moisture content of soil, so it is of great scientific significance and practical value to study the regularity and boundary conditions of rainfall infiltration. At present, the research on rainfall infiltration regularity and mechanism of unsaturated soil slope is still not perfect, and the orthogonal boundary conditions adopted are defective. The orthogonal infiltration boundary adopts the same boundary treatment method for soils of different properties, and the discrimination mechanism of boundary condition transformation does not accord with the reality of non-orthogonal infiltration, which makes it difficult to guarantee the accuracy of soil infiltration calculation on slope surface. In the process of rainfall infiltration, the existing methods to determine the infiltration capacity of slope soil have defects, which are quite different from the actual non-orthogonal infiltration theory. In order to study the infiltration law of unsaturated soil slope under the condition of rainfall infiltration and to explore the non-orthogonal infiltration boundary conditions, the artificial simulated rainfall infiltration experiment was carried out in this paper, and the numerical simulation was carried out for the rainfall infiltration test of unsaturated soil slope. The research contents are mainly divided into the following aspects: (1) improve on the basis of the original indoor simulated artificial rainfall device, and then meet the requirements of the experiment in this paper; (2) to study the influence of rainfall intensity, slope angle and pore ratio on rainfall infiltration by indoor rainfall infiltration test and numerical simulation of silty clay; (3) the outdoor large-scale rainfall test device is designed, and the rainfall infiltration test is carried out on the unsaturated sandy soil outside the slope. The rainfall infiltration experiment of unsaturated soil slope in indoor and outdoor was studied, and the rainfall infiltration law of unsaturated silty clay and sandy soil slope surface was analyzed. Comparing the experimental results with the numerical simulation results using orthogonal infiltration boundary, it is proved that there are some errors in the infiltration boundary conditions treated according to the orthogonal theory at present. The experimental study on rainfall infiltration on unsaturated soil slope shows that for silty clay with weak permeability, the change of slope angle and rainfall intensity have a significant effect on the rule of rainfall infiltration. However, it is difficult to reflect its significant effect on infiltration rate in numerical simulation. For sandy soil with strong permeability, the relative value of rainfall intensity and saturated permeability coefficient can not be used as the criteria for determining whether the soil will be saturated in the process of rainfall infiltration.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU43

【参考文献】