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

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 of water 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.