| چکیده انگلیسی مقاله |
Soil pollution by hydrocarbon is a significant Geo-Environmental problem that can affect the environmental quality of soil, groundwater and air. Soil can be contaminated by organic materials attributable to leakage from underground or aboveground storage tanks and accidental spills. The response of soil to the contaminants not only depends on the local environment but it is also influenced by factors such as particle size, bonding characteristics among particles, and ion exchange capacity. The transport of contaminant components from soil into groundwater can cause serious problems. The use of contaminated soil and its stabilization can be considered in earthworks such as embankments, backfills, and roads if there is no pathway for leaching of contaminants to underground water or if the contaminants pose no risk to the public and the environment. In some areas the native soil is contaminated with hydrocarbon substances. For performing projects in such areas, because of the haulage distance to suitable soil and economic considerations, often the use of local soil is dictated for construction. Thus, the treatment and stabilization of local soil must be considered. On the other hand, in some areas where the soil has been contaminated and the treatment is not economic, for the design of a project in these areas the effect of the contaminating substance on the soil behavior should be evaluated. Therefore, understanding the mechanical behavior of contaminated soils and their treatment is important. Improving the mechanical behavior of clay soils by stabilization is a means of fulfilling geotechnical design criteria. An investigation into the behavior of a contaminated clay soil with Anthracene and its treatment was carried out through a program of experimental tests.. Anthracene is a representative of one group of hydrocarbon, which are called PAHs (Poly Aromatic Hydrocarbons). PAHs create due to incomplete combustion of fossil fuels or wastes. In order to investigate the effect of cement on the stabilization of clay contaminated soil with Anthracene, the specimens of natural clay soil, contaminated soil with Anthracene, soil-cement and Anthracene-contaminated that is stabilized with different percentage of cement (5, 10, 15 and 20%) in different curing times (3, 7, 14 and 28 days) was prepared by static compaction method at maximum dry density and optimum moisture. Atterberg limits and Unconfined compressive strength (UCS) tests were conducted on the specimens. The results of the experimental work showed that adding Anthracene to clay soil, change the compaction parameters, for example, the dry specific weight of soil is reduced and the optimum water content is increased. Although, adding cement to the Anthracene-contaminated soil, improves the compaction of soil, it increases the dry specific weight and reduced the optimum water content. In addition, adding the Anthracene also is changed the unconfined compressive strength of soil, it reduces strength of soil. Although, adding cement is incresed the strength of the contaminated soil. The amount of increase in the strength is depended on the percent of cement and curing. The results showed that Atterberg limits are increased by adding Anthracene to the clay soil, but are reduced by adding Anthracene or cement or adding Anthracene to soil-cement. The results indicated that adding the Anthracene to the soil, changes its structure to flocculated shape, but the decreasing of friction between soil particles due to adding Anthracene, led the soil particles to move easily together. By the way, the results of this research showed that the cement could stabilize contaminated soil with Antracene. |