岳城水库砂砾石地基孔隙特征对渗透特性的影响研究

发布时间：2019-05-13 12:45

【摘要】：砂砾石存在于第四世纪沉积物，是具有鲜明特征的松散碎屑堆积层。砂砾石地基是水利工程及其他工程建筑物的常用地基，它具有孔隙大、透水性强、承载力差等特点。按照成层特性、地貌地质结构及强弱透水层的组合关系和空间变化，砂砾石地基课划分为单一构造和复杂构造。虽然目前已有很多关于渗透方面的的研究，但大多数局限于特定的试验材料，由于土体具有复杂的结构性，不同的地区的材料具有独特性，所以前人的研究不具有广泛适用性。岳城水库的坝基的砂砾石虽具有砂砾石层的共性，但也具有它的特性，本文针对岳城水库的坝基出现的渗漏问题对岳城水库坝基的砂砾石材料的渗透性做出了研究，并得出一些规律予供参考。本文进行了以下研究：（1）砂砾石地基的特性通过前人的研究发现第四纪砂砾石所处的地里位置有所不同，其地质发展史也不尽相同，，但它们都是外应力和内应力相互作用制约的结果，产生于一定的地质环境中，具有相应的规律可以遵循。成因的多样性和结构的松散性是砂砾石地质的主要特征。砂砾石地基具有孔隙率大、不透水性弱的特性。由松散颗粒组成的砂砾石，粒间几乎没有联结性，它的稳定性关键靠颗粒间的嵌挤和摩擦来维持。（2）进行室内试验，取得相关参数值根据大量文献，本试验确定的试验研究参数为孔隙率、不均匀系数和曲率系数。室内试验分为试样颗粒级配试验、孔隙率测定试验和渗透系数测定试验。前两个试验主要目的是确定试验参数值，渗透系数试验采用常水头法测不同级配下的渗透系数，从而可以研究参数值与渗透系数之间的关系。（3）数据分析与处理对得到的试验数据进行一元和多元回归分析，通过分析细粒含量与渗透系数变化规律得到细粒含量小于40%时渗透系数随细粒含量的增加而减小缓慢，细粒含量超过40%后，渗透系数因细粒含量的增加却急剧减小；通过线性回归分析得到渗透系数与孔隙率、不均匀系数呈线性相关；渗透系数与曲率系数呈三次相关。并得到更好的表达式来表征砂砾石地基渗透系数与孔隙特征的关系。
[Abstract]:Gravel, which exists in the fourth century sediments, is a loose clastic accumulation layer with distinct characteristics. Gravel foundation is a common foundation of water conservancy projects and other engineering buildings. It has the characteristics of large pores, strong permeability, poor bearing capacity and so on. According to the characteristics of stratification, geomorphological geological structure, the combination relationship and spatial change of strong and weak permeable layer, the gravel foundation course is divided into single structure and complex structure. Although there have been a lot of research on infiltration, most of them are limited to specific experimental materials. Because of the complex structure of soil and the uniqueness of materials in different areas, previous studies are not widely applicable. Although the gravel of the dam foundation of Yuecheng Reservoir has the commonness of gravel layer, it also has its characteristics. In view of the leakage problem of the dam foundation of Yuecheng Reservoir, the permeability of gravel material of Yuecheng Reservoir Dam Foundation is studied in this paper. Some laws are obtained for reference. In this paper, the following studies have been carried out: (1) through previous studies, it is found that the location of Quaternary gravel is different, and its geological development history is not the same. However, they are the result of the interaction between external stress and internal stress, which are produced in a certain geological environment and can be followed by the corresponding laws. The diversity of genesis and the looseness of structure are the main characteristics of gravel geology. Gravel foundation has the characteristics of large porosity and weak impermeability. The gravel composed of loose particles has little connection between particles, and its stability is maintained by the extrusion and friction between particles. (2) the laboratory tests are carried out, and the related parameters are obtained according to a large number of literature. the experimental parameters determined in this experiment are porosity, inhomogeneity coefficient and curvature coefficient. The laboratory test is divided into sample particle gradation test, porosity test and permeability coefficient test. The main purpose of the first two tests is to determine the test parameters. In the permeability coefficient test, the constant head method is used to measure the permeability coefficient under different grades, so that the relationship between the parameter values and the permeability coefficient can be studied. (3) univariate and multiple regression analysis of the test data is carried out by data analysis and processing. By analyzing the variation of fine grain content and permeability coefficient, it is found that the permeability coefficient decreases slowly with the increase of fine grain content when the fine particle content is less than 40%. When the fine particle content exceeds 40%, the permeability coefficient decreases sharply with the increase of fine grain content. Through linear regression analysis, it is found that the permeability coefficient is linearly correlated with porosity and inhomogeneity coefficient, and the permeability coefficient is correlated with curvature coefficient three times. A better expression is obtained to characterize the relationship between permeability coefficient and pore characteristics of gravel foundation.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV223.4

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