【作者】 吴胜军；

【导师】 王桂尧；

【作者基本信息】 长沙理工大学 ， 岩土工程， 2010， 硕士

【摘要】 红粘土是一种广泛存在于岩溶地区的一种高液限土,是石灰岩风化的产物,在我省湘南地区分布广泛。湖南在建的郴(州)-宁(远)高速公路沿线就有大量红粘土分布,由于红粘土特殊的工程性质,采用未做处理的红粘土填筑路基,通常存在天然含水率高、水稳定性差、压实度低、路基表面易于开裂等问题。废弃这种高液限红粘土换填其它好的路基填料需要新征弃土场与取土场,从而占用土地资源和影响自然环境,因此必须充分利用这种高液限红粘土填筑路基,同时又要研究这种路基由于含水量变化产生病害的机理,以便有针对性的采取工程措施避免这种病害的发生。由于红粘土具有十分显著的干缩开裂特性,因此路基表面易于出现大量的裂缝,裂缝的存在形成了水份入侵与蒸发的良好通道,使水分运移速度加快,导致路基含水量随气候的变化而循环变化,并相应的影响红粘土路基的物理力学性质,为路基病害的产生埋下隐患。因此对红粘土路基水病害形成机理开展研究,对避免红粘土路基的病害形成具有重要作用。本文通过对红粘土地区路面开裂状况的调查,在施工现场典型地段进行了相关的选点、现场试验、取土、红粘土开裂土样模型制作等工作;在室内开展了红粘土物理力学试验、红粘土路基裂缝开展规律试验、红粘土路基渗透特性试验、红粘土路基水份运移规律试验;针对现有仪器、手段的不足,研制及开发出适用于测定不同情况下土体渗透性能的仪器及装置:原位精控渗透仪(现场测定渗透系数)、有压渗透仪(室内测定荷载条件下砂性土饱和渗透系数)、变水头压力渗透仪(室内测定荷载条件下粘性土饱和渗透系数)、非饱和土水分运移规律试验测定装置;采用Geo-Studio系列软件对郴(州)-宁(远)高速公路某典型断面建立实体模型,对降雨条件下,红粘土路基水分运移规律进行了数值模拟研究。从而为高速公路红粘土路基病害的处治技术提供有益的参考。更多还原

【Abstract】 Red clay is a kind of high liquid limit soil widespreads in karst zone, which forms as a result of the weathering from limestone, and widely distributing in the southern region of our province. along the highway project ChenZhou–NingYuan Expressway, there is a great deal of red clay,because of the special engineering properties ,using the red clay without pretreatment for the subgrade filling caused a lot of engineering problems,such as high natural moisture content, poor water-stability, low compaction degree, embankment surface is vulnerable to cracking, etc. Changing the high liquid limit red clay for better soil need more place to deposit the waste and provide better soil,that will occupy land resources and influense our nature enviroment. Therefore, we have to make full use of this high liquid limit red clay to subgrade filling,and study the mechanism of the disease caused by moisture changing so that to prevent the disease by proper measures.Red clay has a very significant cracking characteristics, so embankment surface is vulnerable to cracking, crack is good channel for water invasion and water evaporation, which speed up the moisture it moves and Lead to the circulation of moisture content changed with climate, consequently, it influences the physical nature of the red clay and makes the hidden trouble of the disease. So the research for the mechanism of water-disease of subgrade filling by red clay will play a vital role to avoid the disease. This article made a investigation for the cracking situation of the embankment surface in the red clay area, and made the representative jobs in the typical location during the excavation construction, such as selecting location , insitu tests, collecting earth,the establishment of cracking model of red clay;we carryed out some tests for the red clay in room:physical and mechnical properties tests,cracking test, permeability test,moisture migration regularity test; againsting the existing problem of insufficient apparatus and means, some new apparatus and devices were developed for determing the water permeability of the soil under different situations,such as:field water permeability measurement apparatus with precise control(water permeability measures in situ),water permeability measurement apparatus with compressive stress(water permeability measures in room for saturated sand ), water permeability measurement apparatus with varying head and compressive stress(water permeability measures in room for saturated clay ), moisture migration measurement devices for unsaturated soil.Finally,use Geo-Studio series software to set up model of a typical cross-section of the filled embankment in highway project of ChenZhou–NingYuan Expressway ,the numerical simulation of the moisture migration regularity under the condition of rainfall in embankment filled by red clay is carried out ,thus to provide useful reference for the treatment technology of the embankment disease.更多还原