【作者】 拓向阳；

【导师】 张炜；

【作者基本信息】 长安大学 ， 岩土工程， 2009， 硕士

【摘要】 随着近年来我国国民经济的发展和西部大开发战略的实施,关中地区逐渐成为陕西省的发展中心,乃至整个西北地区的发展中心。在这一地区进行的工程建设数量越来越多,规模也越来越大。但是关中东部渭河以南地区由于以往的工程建设较少,该区域黄土的湿陷性以及黄土成因的研究相对较少。对于该区域黄土湿陷的特性以及黄土的成因进行的研究,可以深入理解该区域黄土的形成,准确评价黄土的湿陷等级,更好的为工程建设服务。这在理论研究与工程实践方面都有着积极的意义。黄土高原深厚的黄土源于西北干旱地区沙漠中的粉尘在西北风的搬运作用下堆积而成,具有由西北向东南粒度逐渐变细、黄土厚度由厚变薄、黄土湿陷性由强变弱的趋势。但在黄土高原南缘关中东部渭河以南地区,上述变化规律出现异常。本文结合工程实际,通过室内土工试验及野外现场浸水试验对该区某工程场地黄土的湿陷性进行了深入研究。发现该区黄土的湿陷性较强烈,属自重湿陷性黄土场地,地基湿陷等级为Ⅳ级。现场浸水试验实际获得的自重湿陷量为依据室内试验结果按照现行湿陷性黄土规范计算的自重湿陷量的3.1倍以上。同时对关中东部渭河以南地区黄土地层及其厚度进行了广泛的调查研究,选择南北两条线路,分渭河二级阶地、三级阶地和黄土塬三个地貌单元六个黄土剖面,研究晚更新世以来的黄土地层及其厚度,并与洛川黄土剖面及渭北黄土台塬的黄土进行对比,发现研究区域晚更新世以来的黄土厚度变化有以下特征,渭河三级阶地黄土厚度最大,二级阶地黄土厚度次之,黄土台塬的黄土厚度最小。黄土粒度分析结果显示,＞63μm颗粒平均含量达11.70%,与陕北吴堡一带的黄土类似。渭河北岸大荔沙苑地貌形态及古风向的证据以及现代气象资料显示的主导风向均为东偏北风,证明该区黄土中的粉细沙颗粒主要来源于渭河、洛河、黄河的河漫滩以及其交会处的沙苑,属近源堆积。近源物质的大量堆积,造成本区黄土颗粒较粗而且厚度大、黄土堆积的速率快,使得黄土的成土作用差,土质疏松,湿陷性强烈,工程性质很差。更多还原

【Abstract】 With the development of the national economy in recent years, China’s western development strategy and the Guanzhong area became Shanxi Province’s development center gradually, and even entire northwest local development center. The engineering construction quantity carries on which in this area are more and more many, the scale more and more is also big. But in eastern of central Shaanxi plain-South of Weihe River are few as a result of the former engineering construction, this area loess collapsibility as well as the loess formation research relative few. For the area of the characteristics of loess collapsibility and loess formation of the study, Can help understand of the formation of loess in the area in depth, accurate evaluation of loess collapsibility grades, better service for the project construction. This theoretical research and engineering practice have a positive significance.The deep loess of loess plateau come from dust in northwest arid area desert ,under the northwest wind transporting function. From northwest to the southeast loess particle size become smaller, loess thickness become thinner, the loess collapsibility become weaker. But south of the loess plateau , in eastern of central Shaanxi plain-South of Weihe River, the above change rule appears exceptionally.In this paper, combined with engineering practice, through the soil test indoor and field immersion test of collapsible loess under overburden pressure conducted an in-depth research. Found loess collapsibility relatively strong in the area, which is the site of loess collapsible under overburden pressure, the ground rank of collapsibility is wetIV level. Collapse under overburden pressure from field immersion test is 3.1 times from Indoor calculation. Stratum and its thickness are carried out an extensive investigation and research, select the two north-south line, since has divided the Weihe River two stage, three stage and the loess plateau three landform unit six loess section to Research since the Late Pleistocene loess and their thickness and found that the study area since the Late Pleistocene loess thickness has the following characteristics ,which is the loess thickness of three stage of Weihe River is the largest, two stage is larger, loess plateau is thinner. Loess particle size analysis results showed that,>63μm average particle content of 11.70 percent, is similar with wubu loess of northern Shaanxi. Geomorphological patterns of Dali Astragalus complanatus of Weihe river north , the evidence of dominant wind direction and Modern meteorological data showed that the dominant winds are northerly winds east to prove that the area of the loess powder sand particles from the River floodplain of Weihe River , Luohe River and Yellow River and Astragalus complanatus of its river Interchange, which is near the source of accumulation. Near the source of a large number of material accumulated, resulting in loess particles is bigger,loess thickness is larger in this area and the loess stack speed are quick, making the loess intp soil is poor, soil loose, collapsibility strong, the project nature is very bad..更多还原