柴油污染重塑红黏土直剪力学特性试验研究

DIRECT SHEAR TESTS FOR MECHANICAL PROPERTIES OF RED CLAY REMOLDED WITH DIESEL OIL POLLUTION

广西红黏土分布区柴油泄漏对土体造成了一定程度污染,为研究轻质非水相非极性柴油孔隙液对红黏土力学性质的影响,本文以0~#柴油为添加剂对其重塑样进行不排水快速直剪试验,测得了不同含水率、含油率、法向压力下红黏土抗剪强度及其参数变化规律。研究结果表明:在土-水-油系统中,非极性柴油孔隙液对红黏土强度影响相对较小,且受含水率影响。同一含油率时,红黏土抗剪强度、内摩擦角、黏聚力均随含水率增加而降低;同一含水率时,法向压力影响柴油作用模式,随含油率增加,抗剪强度参数变化较为复杂,当含水率为20%,红黏土内摩擦角、黏聚力反向波动变化;同一含湿率时,柴油比例的提高导致红黏土抗剪强度参数的增大。扫描电镜观察发现,非极性柴油孔隙液的介入,改变了水-土系统的静电及结构模式,导致红黏土强度发生变化,通过所建的"多尺度多阶段柴油作用微结构模型",阐明了柴油孔隙液对红黏土强度特性影响的微观机理。

The leakage of diesel oil in the distribution area of red clay in Guangxi has caused a certain degree of pollution to the soil. This paper studied the effect of the pore fluid of the light non-aqueous phase non-polar diesel on mechanical properties of red clay. It used 0#diesel as additives and undrained quick direct shear test method to explore the strength characteristics of red clay. It measured the variations of shear strength parameters under different moisture contents,oil contents and normal pressures. The results show that the pore fluid of the non-polar diesel has relatively small influence on the strength of red clay in the soil-water-oil system. It is affected by the water content. The shear strength,internal friction angle and cohesion of red clay decrease with the increase ofwater content in the same oil content. In the same water content,normal pressure influences the mode of diesel oil effect and the variation of shear strength parameters is more complicated with the increase of oil content. When the water content is 20%,as the increase of oil content,the internal friction angle and cohesion fluctuate in the opposite direction. With the same moisture content,the increase of the proportion of diesel oil leads to the increase of the shear strength parameters of red clay. SEM shows that the intervention of the pore fluid of the non-polar diesel changes the electrostatic and structural mode of the water-soil system and leads to changes in the strength of red clay. The paper established＂multiscale and multistage diesel oil effect microstructure model ＂ and clarified the microscopic mechanism of the influence of diesel pore fluid on the strength characteristics of red clay.