【作者】 梁翔；

【导师】 郑柯；

【作者基本信息】 湖南大学 ， 道路与铁道工程， 2007， 硕士

【摘要】 膨胀土作为一种特殊性质粘土,在世界各地和我国的大部分地区都有广泛分布。近年来,随着我国国民经济迅猛发展,高等级公路大量兴建,不少高等级公路都穿越了膨胀土发育地区。由于膨胀土遇水体积膨胀,失水收缩开裂,工程性质极差,直接填筑路基会造成严重路基病害,不宜直接用作路基填料。但是如果简单作弃方处理,又会增加工程造价,同时大量的弃方会污染公路沿线周边环境,不利于沿线环境保护,因此膨胀土路基问题研究是摆在我国广大公路建设者面前一项较为紧迫的任务。本文以广西崇左至上思二级公路建设项目为依托,在现场土质调查基础上,针对膨胀土的不良工程特性进行膨胀土的试验研究。本文利用公路工程中的常规试验指标和SOM神经网络模型对膨胀土进行判别和分类,合理确定公路沿线膨胀土的胀缩等级,并通过试验进行了验证。通过大量的试验研究,建立了击实膨胀土样膨胀变形量、膨胀力以及抗剪强度与土样初始含水量、干密度和上覆压力之间的定量关系,以此作为膨胀土边坡稳定性分析的依据。推导了考虑含水量和膨胀力对膨胀土边坡稳定性影响的极限分析安全系数公式,并进行了相应的计算分析。对膨胀土在不同掺水泥、掺砂、掺好土比例的条件下进行物理和力学性质试验研究,分析各工程性质指标在不同配合比和含水量条件下的变化规律,为确定经济合理的改良方案、施工工艺、施工控制措施提供依据。采用土工布包盖法和三明治互层法铺筑试验路。通过对试验路现场跟踪调查与性能指标检测,评价试验路实际效果。综合分析研究膨胀土改良加固方案的经济性,结果表明:利用土工布包盖法和三明治互层法填筑路基,具有明显的经济效益和社会效益。更多还原

【Abstract】 Expansive soil, as a kind of special clay, distributed broadly in most places of our country and all around the world. These years, along with the swift development of our country economy and the large scale constructing of high-grade highway, some high-grade highways run across the area where the expansive soil develops. Because the expansive soil expands when absorbing water,shrinks and cracks when losing water, it has poor engineering property, and the roadbed will be damaged seriously if the expansive soil is filled in the roadbed directly. But if it’s just abandoned simply as useless stuff, the cost of the project will grow and the environment around the road will be polluted. So it is an urgent task for our builders to work over roadbed with expansive soil.This thesis, based on the project of Chong-shang highway in Guangxi, studies and tests the expansive soil on its poor engineering property. By using highway project’s conventional test indices and SOM neural network model, the thesis rationally identifies and classifies the swell-shrink grades of the expansive soil along the road, and verifies them through the tests. By a lot of laboratory tests of compacted expansive soil, the thesis establishes a quantitative relationship between the expansion deformation, expansive pressure, shear strength and the beginning water content, dried density and the overburden pressure, as a basis of the stability analysis of expansive soil slope. The thesis derives a safety factor equation of limit analysis which considers the effect of water content and expansive pressure on the stability of expansive soil slope, and calculates and analyzes data on the equation. We tests and studies the physical and mechanical property of expansive soil formed with different ratios of cement , sand and good soil to analyzes the variation rules of all kinds of engineering property indices under the condition of different ratios and water contents, and to provide a suggestion of reasonable economic improving programs, construction technologies, construction control measures. Earthwork fabric treatment method and sandwich interbedding method are introduced to build the test road in our study, and we evaluate the actual effect on the test road through spot-tracking survey and property indices examination of the test road. Analyzing the economy quality of the improving reinforcing project of expansive soil on the whole, we arrive at the conclusion that it has obvious economic and social benefit by using earthwork fabric treatment method and sandwich interbedding method to fill and build the roadbed with expansive soil.更多还原