پديد آورندگان :
خلوصي، محمد مهدي دانشگاه تهران , رئيسي استبرق، علي دانشگاه تهران - گروه آبياري و آباداني , عبداللهي، جمال دانشگاه تهران - مربي گروه آبياري و آباداني
كليدواژه :
حدود اتربرگ , زمان عمل آوري , فلوكولاسيون , مدول الاستيسيته خاك
چكيده فارسي :
در اين پژوهش، رفتار يك خاك رسي آلوده به ماده هيدروكربني آنتراسن و امكان بهسازي آن جهت بهبود خواص فيزيكي و مكانيكي، با افزودن سيمان، مورد مطالعه قرار گرفت. بدين منظور، نمونه هاي خاك طبيعي، خاك آلوده به آنتراسن، خاك-سيمان و خاك آلوده اختلاط يافته با سيمان در مقادير (5، 10، 15و 20 درصد) سيمان تهيه شدند و بر روي آنها آزمايش مقاومت فشاري محصور نشده (USC) و حدود اتربرگ انجام شد. جهت انجام آزمايش مقاومت، از روش تراكم استاتيكي اقدام به ساخت نمونه ها شد و آزمايش روي نمونه هاي حاوي سيمان در زمان عمل آوري (3، 7، 14 و 28 روزه) صورت پذيرفت. نتايج نشان داد كه افرودن آنتراسن، سبب افزايش حدود اتربرگ در خاك آلوده نسبت به خاك طبيعي مي گردد. افزودن سيمان به خاك طبيعي و خاك آلوده به طور كلي حدود اتربرگ در نمونه ها را كاهش مي دهد. همچنين نتايج نشان داد آلودگي خاك به آنتراسن، كاهش مقاومت خاك آلوده نسبت به خاك طبيعي را در پي دارد. با افزودن سيمان به خاك آلوده، مقاومت آن افزايش مي يابد؛ اين افزايش مقاومت تابعي از درصد سيمان بكار رفته و زمان عمل آوري است. از طرف ديگر نتايج بدست آمده از مدول الاستيسيته خاك حاكي از افزايش شكنندگي خاك آلوده اختلاط يافته با سيمان است كه با افزايش درصد سيمان بكار رفته و يا زمان عمل آوري، اين شكنندگي بيشتر مي گردد.
چكيده لاتين :
Pollution of the soil by hydrocarbon is a significant Geo-Environmental problem that may 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 also is 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. Use of contaminated soil and its stabilization can be considered in earthworks such as embankments, backfills, and roads where 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, use of local soil is dictated for construction as a result of haulage distance and economic considerations. Thus, the treatment and stabilization of local soil must be considered. On the other hand, in the areas where the soil has been contaminated and the treatment is not economical, effects of the contaminating substance on the soil behavior should be evaluated for the design of the projects. 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 on the behavior of a contaminated clay soil with Anthracene and its treatment is carried out through an experimental program. Anthracene is a representative of a group of hydrocarbon, which are called PAHs (Poly Aromatic Hydrocarbons). PAHs are created 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, several specimens are prepared by static compaction method at maximum dry density and optimum moisture. The specimens are of natural clay soil, contaminated soil with Anthracene, soil-cement and Anthracene-contaminated stabilized with different percentage of cement (5, 10, 15 and 20%) in different curing times (3, 7, 14 and 28 days). Atterberg limits and Unconfined compressive strength (UCS) tests are conducted on the specimens. The results of the experimental work show that adding Anthracene to clay soil, changes the compaction parameters. As an 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 reduces the optimum water content. In addition, adding the Anthracene may change the unconfined compressive strength of soil and will reduce the strength of soil. The strength of the contaminated soil is increased by adding cement. The amount of increase in the strength is depended on the percentage of cement and curing (type or time). The results show that Atterberg limits are increased by adding Anthracene to the clay soil, but are reduced by adding Anthracene or cement to soil-cement. The results indicate that adding the Anthracene to the soil, changes its structure to flocculated shape, but decrease of friction between soil particles due to adding Anthracene, may lead the soil particles to move easily together. By the way, the results of this research show that the cement could stabilize contaminated soil with Antracene.
