Experimental Study On The Soil Polluted By Oil Handled With Cement-Based Material In Sichuan-Tibet Railway

The construction of Sichuan-Tibet Railway is a major project concerned by the people all over the country and even the whole world.The Sichuan-Tibet Railway passes through many water sources and ecologically sensitive areas in China.The State attaches great importance to the protection of the ecological environment along the Sichuan-Tibet Railway Line.The construction process of sichuan-tibet railway will inevitably lead to the leakage of various types of diesel oil and engine oil,which will gradually penetrate into the deep soil layers through osmosis,endangering the survival of surrounding plants and animals,affecting the material exchange of the earth's ecosystem,and ultimately affecting the ecological balance of the whole earth.Therefore,in view of the problem of oil-contaminated soil in the construction process,comprehensively considering the high reliability requirements of concrete structure,this paper proposes to use cement mortar to solidify oil-contaminated soil in order to realize the green,harmless and resource utilization of pollutants,which has dual value of environmental protection as well as economy.Through the systematic research on the performance of cement mortar mixed with oil-contaminated soil,the main conclusions are as follows:1)The fluidity of cement-based materials mixed with oil and oil-contaminated soil was studied,oil or oil-contaminated soil increases the plastic viscosity and yield stress of cement paste.The incorporation of diesel oil,diesel oil-contaminated soil or engine oil-contaminated soil will increase the thixotropy of cement paste and reduce the fluidity of cement mortar.A single incorporation of engine oil has the opposite effect;2)The hydration characteristic of cement mixed with oil and oil-contaminated soil was studied,oil-contaminated soil will reduce the cumulative hydration heat of cement for 3 days,increase the peak rate of hydration heat release during the accelerated hydration period,increase the rate of decline of hydration heat during the decelerated hydration period and decrease the relative content of calcium hydroxide and ettringite in the 14-day hydration phase.3)The flexural and compressive strength of cement mortar mixed with oil and oil contaminated soil was studied.The strength of cement mortar will be reduced by diesel orengine oil-contaminated soil to a certain extent,and the degree of reduction varies according to the type of oil,and the incorporation amount of oil or oil-contaminated soil;4)The capillary water absorption characteristic of cement mortar mixed with oil and oil-contaminated soil was studied.When diesel,engine oil and oil-contaminated soil are mixed,the water adsorption rate of cement mortar specimens decreases with the increase of the content,and the capillary water absorption of the specimens decreases gradually.The water adsorption rate of the specimens mixed with diesel-contaminated soil was lower than that of the specimens only mixed with oil.Compared with the single-mixed engine oil group,the cement mortar specimens mixed with engine oil-contaminated soil has a higher water adsorption rate in the initial stage of capillary water absorption,and becomes lower in the later stage.5)The solidification effect of oil-contaminated soil cement mortar was evaluated.Cement mortar has a good solidification effect on oil-contaminated soil.The oil content in solid leaching solution is lower than the national standard value of 5mg/L.It is feasible to use cement mortar to solidify oil-contaminated soil.