In order to figure out the effect of oil seepage pollution on environmental geotechnical engineering practice, the influence of No.0 diesel on air-dried cracks of clay soil was studied in the investigation. Firstly, laboratory tests were conducted to simulate the air-dried process of soil contaminated by diesel oil at different oil contents (0, 4%, 8% and 12%). Then, digital images of soil cracks were processed with softwares such as Photoshop and ArcGIS to obtain fractal dimension and common morphological parameters (e.g. average crack width, crack length and surface crack rate). Finally, the development trend of the cracks for different oil contents was analyzed and the mechanism of diesel oil acting on the fracture's formation and development was discussed. The results show that crack development of oil-contaminated soil is similar to that of unpolluted soil. While diesel oil content increases, the development process of the cracks becomes slow. Moreover, both average crack width and surface crack rate decrease gradually with the increase of oil content. The presence of oil can hinder the formation of long cracks from running though the soil body and consequently promote the development of shorter fissures. Fractal dimension decreases with the increase of oil content, which means that fracture development is not good for the soil contaminated by diesel oil. Surface tension of oil film between soil particles and the polymer oil chains of diesel oil increases the cohesion and tensile strength of soil, and as a result, it makes cracks not easy to develop.%为了解油品渗漏污染问题对环境岩土工程实践的影响,以0号柴油污染为例,研究油污粉质黏土干裂隙的特征规律.首先将不同含油率(0,4%,8%,12%)的柴油污染粉质黏土泥浆放入玻璃器皿中进行自然晾干,然后采用Photoshop和ArcGIS等软件对不同含油率土样的干裂隙进行数字图像处理,获取裂隙平均宽度、裂隙长度、面裂隙率和分形维数等参数.最后分析不同含油率条件下粉质黏土干裂隙发育规律,探讨柴油对粉质黏土干裂隙形成与发展作用机理.研究结果表明:与未污染土相比,柴油污染土干裂隙发育较缓慢,且含油率越高,发育越慢;裂隙平均宽度和面裂隙率均随含油率增加而逐渐减小;柴油进入土中会抑制较长裂隙的发展,形成较短的干裂隙,裂隙的开裂程度随含油率增大而降低;干裂隙的分形维数随含油率的增加而减小,分形维数越小,裂隙越不发育;土颗粒间的油膜表面张力和柴油高分子油链作用使得粉质黏土的黏聚力增强,抗拉强度增大,干裂隙发育程度低.
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