降雨条件下人工堆山坡体的渗流及稳定性分析

发布时间：2018-06-12 19:36

本文选题：人工堆山 + 土石混合体　；参考：《南京大学》2015年硕士论文

【摘要】：随着城市建设的发展,城市拆迁改造、河道清淤、矿山治理等工程将会产生大量的工程弃土和固体废弃物,如何处理这些弃土和固体废弃物是当前研究的热点。近年来,人工堆山工程的提出是有效解决城市固体废弃物、处置环境岩土工程问题的重要举措之一。人工堆山有别于自然山体,其边坡堆载体常为工程弃土和固体废弃物的混合体,故研究人工堆山边坡堆载体的渗透性、膨胀性,以及降雨情况下人工堆山边坡渗流场对人工堆山安全性和稳定性的影响具有重要意义。本文以土石混合体模拟人工堆山边坡堆载体,选取下蜀土作为细粒(土)材料,分别添加0%、15%、30%和45%含量的不规则形状角砾,同时控制土石混合体的干密度,采用自行设计的新型渗透膨胀仪对土石混合体的渗透性及膨胀性进行研究。运用Geo-Studio有限元软件中的渗流分析模块和边坡稳定分析模块,对镇江某人工堆山在不同方案下降雨入渗过程中边坡渗流场的动态变化进行数值模拟,并结合极限平衡法,分析不同方案降雨过程中的边坡稳定性。本文的主要研究成果如下：(1)本文设计了一种新型渗透膨胀仪,在满足土石混合体试样尺寸要求的同时,可以在工程现场较快地测得原位或重塑试样的渗透速率和膨胀量。(2)试验结果显示,土石混合体的渗透速率随含石量的增加而增加,两者存在指数关系,满足k=k0enp;而膨胀量随着含石量的增加而减小,两者存在线性关系；土石混合体的渗透速率随干密度的增加而减小,膨胀量随干密度的增加而增加；土石混合体的渗透膨胀率和膨胀含水率两者存在较明显的线性关系。且新型渗透膨胀仪所测得土石混合体的渗透速率与柔性壁渗透仪所得的饱和渗透速率规律具有一致性,两者相差近一个数量级。(3)数值模拟结果显示,降雨强度越大,边坡土体内的体积含水率变化范围越大,坡体表面出现暂态饱和区的时间也越早；降雨持时越长,其影响深度和范围也越大。坡脚处土体的体积含水率所受影响最大。(4)降雨入渗过程中,最先影响到的是边坡表层的土体,表层土体的孔隙水压力随着降雨的持续而逐渐增大,直到孔隙水压力为零。降雨过程中坡脚处的负孔隙水压力最先上升到零,对边坡稳定性产生重要影响,应在设计和治理时予以重视。(5)降雨强度越大,持续时间越长,雨水入渗的范围也越大,入渗量越多,边坡的安全系数下降的越快。且安全系数的最小值不是在降雨结束时刻出现,而是存在一定时间的滞后性。
[Abstract]:With the development of urban construction, many engineering projects, such as urban demolition and reconstruction, river desilting, mine treatment and so on, will produce a large number of engineering abandoned soil and solid waste. How to deal with these abandoned soil and solid waste is a hot research topic at present. In recent years, artificial mountain building project is one of the most important measures to solve the problem of urban solid waste and environmental geotechnical engineering. The artificial mountain pile is different from the natural mountain body, and the slope pile carrier is usually a mixture of engineering abandoned soil and solid waste, so the permeability and expansibility of the artificial mountain slope pile carrier are studied. The influence of seepage field on the safety and stability of artificial mountain slope under rainfall is of great significance. In this paper, a mixture of earth and rock was used to simulate the carrier of artificial pile slope, and Xiashu soil was selected as fine grained (soil) material, and the irregular shape breccia with 30% and 45% content of 0 15% and 45% content was added, respectively, and the dry density of the mixture was controlled at the same time. The permeability and dilatability of soil and rock mixture were studied by a new type of osmotic dilatometer designed by ourselves. The seepage analysis module and slope stability analysis module of Geo-Studio finite element software are used to simulate the dynamic change of slope seepage field in the process of rainfall infiltration under different schemes, and combined with limit equilibrium method. The slope stability of different schemes during rainfall is analyzed. The main research results of this paper are as follows: (1) in this paper, a new type of osmotic dilatometer is designed, which meets the requirements of the sample size of soil-rock mixture at the same time. The permeability rate and expansion of in-situ or remolded samples can be measured quickly in the engineering site. The results show that the permeability rate of soil-rock mixture increases with the increase of rock content, and there is an exponential relationship between them. The content of swelling decreases with the increase of rock content, and there is a linear relationship between them, and the permeation rate of soil-rock mixture decreases with the increase of dry density, and the amount of expansion increases with the increase of dry density. There is an obvious linear relationship between the permeability expansion ratio and the swelling water content of the mixed soil and rock. The results of numerical simulation show that the infiltration rate of soil-rock mixture measured by the new dilatometer is consistent with the saturated permeability rate obtained by the flexible wall osmometer, and the difference between them is nearly an order of magnitude. The numerical simulation results show that the rainfall intensity is greater. The larger the variation range of volume water content in slope soil is, the earlier the transient saturation zone appears on the slope surface, and the longer the duration of rainfall is, the greater the depth and range of influence will be. In the process of rainfall infiltration, the first influence is on the surface soil of the slope. The pore water pressure of the surface soil increases gradually with the continuous rainfall, until the pore water pressure is zero. In the process of rainfall, the negative pore water pressure at the foot of the slope rises to zero first, which has an important effect on the slope stability. The greater the rainfall intensity and the longer the duration, the larger the Rain Water infiltration range should be paid attention to in the design and treatment. The more the infiltration, the faster the safety factor of the slope decreases. And the minimum value of safety factor does not appear at the end of rainfall, but has the lag of a certain time.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43

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