【摘要】：膨脹土是一種親水性強,遇水膨脹的土體,易造成工程破壞,是地質災害發(fā)生主要誘因之一,同時也是一項全球性的治理難題。南水北調是國家解決北方缺水的重要戰(zhàn)略工程,南水北調中線全程長1277公里,但其在南陽、沙河等地區(qū)共穿越了387公里的膨脹土地帶,對其渠道邊坡產生了不同程度的破壞,因而解決南水北調膨脹土渠道邊坡問題成為該工程的重中之重。國內許多專家學者對南北北調膨脹土已展開了很多研究,但其都是對于膨脹土的開裂特性,降雨入滲,及內部軟化結構面等多方面進行探討,而鮮有考慮到地下水對于南水北調渠道邊坡的影響。本文經過對南水北調中線的勘查,總結了渠道邊坡的破壞形式,通過試驗得出膨脹土的物質組成、化學成分及基本物理性質,分析其膨脹土地質特征。通過對南水北調邊坡的破壞形式和開挖渠坡的脹縮結構面研究,把南水北調渠坡的破壞模式總結歸納為3大類,用以認識膨脹土破壞類型與指導膨脹土渠道邊坡的加固方案。對南水北調中線膨脹土進行現(xiàn)場取樣,進行了大量室內試驗,重點研究了其脹縮性能、受干濕循環(huán)影響的抗剪強度變化、滲透系數(shù)和土水特征曲線。根據試驗段實際工況建立數(shù)值模型,通過數(shù)值模擬和現(xiàn)場監(jiān)測數(shù)據分析渠道邊坡的顯著影響區(qū)深度,分析其渠道邊坡內的滲流場分布情況,并耦合邊坡穩(wěn)定性對其安全系數(shù)進行驗算,得出其渠道邊坡破壞機理。從而針對其破壞機理,提出了一套適用一級渠坡以上的內外結合排水+土工格柵加筋體+坡面三維植草的綜合防護措施,分析了加固機理措施。本文總結了南水北調渠道邊坡的破壞模式,分析確定了大氣干濕循環(huán)影響區(qū)深度,從上層滯水和大氣相互作用影響等方面,分析其滲流場分布情況,并分析其安全穩(wěn)定性,揭示膨脹土渠道邊坡的破壞機理,并針對的提出一種綜合防護方案,希對南水北調工程膨脹土的研究與防護治理有指導作用。
[Abstract]:Expansive soil is a kind of hydrophilic swelling soil which is easy to cause engineering damage and is one of the main causes of geological disasters and also a global problem of governance. The South-to-North Water transfer Project is an important strategic project for the country to solve the water shortage in the north. The middle line of the South-to-North Water transfer Project is 1277 kilometers long, but it has passed through 387km of expansive land zones in Nanyang, Shahe and other areas, which has caused damage to its canal slope to varying degrees. Therefore, it becomes the most important project to solve the problem of channel slope of the expansive soil in the south-to-north water transfer project. Many domestic experts and scholars have carried out a lot of research on the expansive soil transferred from north to south, but its cracking characteristics, rainfall infiltration, and internal softening structure surface have been discussed in many aspects, such as the cracking characteristics of the expansive soil, the infiltration of rainfall, and the internal softening structure surface, etc. However, the influence of groundwater on the channel slope of the South-to-North Water diversion Project is rarely considered. Based on the survey of the middle route of South-to-North Water transfer Project, the failure form of channel slope is summarized. The material composition, chemical composition and basic physical properties of expansive soil are obtained by experiments, and the characteristics of expansive soil are analyzed. Through the study on the failure form of the slope of the South-to-North Water transfer Project and the expansion and shrinkage structure surface of the excavated canal slope, the failure modes of the channel slope of the South-to-North Water transfer Project are summarized into three categories, which can be used to understand the failure type of expansive soil and to guide the reinforcement scheme of the expansive soil canal slope. Field sampling of expansive soil in the middle line of South-to-North Water transfer Project was carried out, and a large number of laboratory tests were carried out. The expansion and shrinkage properties, shear strength change affected by dry-wet cycle, permeability coefficient and soil-water characteristic curve were studied. According to the actual working conditions of the test section, the numerical model is established, and the distribution of seepage field in the channel slope is analyzed by numerical simulation and field monitoring data to analyze the depth of the significant influence area of the channel slope. The failure mechanism of channel slope is obtained by checking and calculating the safety factor of the coupled slope. In view of its failure mechanism, a set of comprehensive protection measures for three dimensional grass planting on the slope surface of the inner and outer combined drainage geogrid are put forward, and the reinforcement mechanism measures are analyzed. In this paper, the failure mode of channel slope of South-to-North Water transfer Project is summarized, and the depth of dry and wet circulation in the atmosphere is determined. The distribution of seepage field and its safety and stability are analyzed in terms of the interaction between the upper layer of stagnant water and the atmosphere. The failure mechanism of expansive soil channel slope is revealed, and a comprehensive protection scheme is proposed, which is expected to guide the research and protection of expansive soil in South-to-North Water transfer Project.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TV672;TV223
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本文編號：2295133