【作者】 朱崇辉；

【导师】 刘俊民； 李鹏；

【作者基本信息】 西北农林科技大学 ， 岩土工程， 2006， 硕士

【摘要】 土是地壳表层岩石风化的产物,是多种矿物颗粒的集合体;粗粒土具有广义和狭义之分,广义的粗粒土则是泛指颗粒直径较粗的土,狭义的粗粒土则根据不同的国家及其不同的部门存在不同的具体分类标准。粗粒土作为建筑地基或建筑材料从古至今都有广泛的应用,对土的理论研究是从欧洲工业革命开始的,而对其作为一门科学进行系统研究,则认为是从太沙基1925年发表了世界上第一本土力学专著后开始的。土力学产生到现在已有80余年的历史,对土的研究取得了系统丰硕的成果,这些成果指导了城市、交通及水利建筑等行业的飞速发展。对土的研究,早期所取得的理论成果,大都属于细粒土的范畴,相对较早出版的专著对粗粒土很少有系统论述。随着岩土工程的发展,粗粒土作为建筑材料应用越来越广,近年来,不少土力学专家也开始把目光重点投向了粗粒土的理论研究,开始取得了许多有价值的理论成果。其中,刘杰的“土的渗透稳定与渗流控制”,郭庆国的“粗粒土的工程特性及应用”,就是粗粒土研究理论成果的典型代表。粗粒土有许多建筑工程上的优点,但在水利建筑中利用粗粒土优点的同时,相伴出现的不利因素也不可回避。渗透系数大,渗透稳定性差,容易发生坝体渗漏和渗透破坏是粗粒最大的缺点。为了更深入的把握粗粒土的渗透特性,本文针对在坝体反滤结构中应用较多的0.1mm至20mm的粗粒土为研究对象,运用试验方法,重点在密度、级配对粗粒体的渗透系数和渗透变形的影响方面,展开了粗粒土的渗透特性试验研究,通过对资料的整理和分析,建立了粗粒土渗透系数模型,并取得了以下几点结论:①粗粒土的渗透系数较大,本文所研究范围内的粗粒土,渗透系数一般都超过10-4cm/s的数量级。渗透系数大,容易降低坝体浸润线,这有利于坝体稳定。粗粒土的渗透系数大小与土体的孔隙比大小有关,孔隙比越大,渗透系数越大,而且存在高度的相关性。渗透系数与土的颗粒级配有关,颗粒组成越粗,渗透系数越大,渗透系数与颗粒级配中的不均匀系数和曲率系数的相关性也可达到高度相关程度。②粗粒土在水力作用下,是一种结构极不稳定的土体,在渗流作用下极易发生渗透变形,容易引起坝体的渗透变形破坏。从渗透系数的变化上分析,其渗透变形过程是一个连续的过程,土体的破坏形式大都属于管涌破坏,破坏坡降较小,一般破坏坡降都小于2.5,有的甚至小于1.0。③孔隙比和级配对粗粒土的渗透系数的影响可用一个与之相关的渗透系数模型表达,计算和试验证明:本次试验所建立的渗透系数模型在粗粒土的计算精度上有较大的提高。更多还原

【Abstract】 The soil is a progeny of the earth crust mother rock strong weathering, is various aggregations of mineral grain, then the coarse-grained soil indicates generally the thicker soil of the grain diameter. The soil conduct constructs the foundation or building the material all have the extensive application up to now from the antiquity, the theories research of the soil is from the European Industrial Revolution, but the theories research of the soil generally accepted for from Terzaghi announced in 1925 in the world the first soil mechanics particularly. There have had already for more than 80 years from the time to now, the people’s research to the soil also obtained the glorious theories result, these results guided the developing of the modern city building industry, the transportation industry, the water conservancy building industry etc..People obtained the glorious theories result, but the target that people studied belong to the category of the fine-grained soil mostly, there were few system discussions about the coarse-grained soil in the primitive published the works, with the development of the geotechincal engineering, the coarse-grained soil as a building material has been wide applied more and more. In recent years, a few experts of the soil mechanics also start throwing the aim to the theories of a soil research, and obtained some worthy theories results. Such as,Liu jie writed“the Soil Permeability Stability and Seepage Flow Control”, Guo Qingguo writed“the engineering characteristic and applications of the coarse-grained soil”, is the typical representative of the coarse-grained soil research theories result.There are many advantages on the construction engineerings to the coarse-grained soil. People make use of its advantage on the water conservancy construct, at the same time, its disadvantageous characteristic also cannot disregard, the big permeability coefficient, the bad permeability stability, the easy occurrence dam body leakage and the seepage breakage and etc.,are all its the biggest weakness.In order to deep holding the engineering characteristic of the coarse-grained soil, this paper researched object that is the coarse-grained soil of the diametre from 0.1mm to 20mm that was often applied in the dam body filter structure, using the experiment method, carrying out the experiment the research of the coarse-grained soil permeability characteristic. The effect is mostly the permeability coefficient and permeability deformation of the coarse-grained soil in the density and the graded, building up a permeability coefficient model更多还原