بررسي تأثير آلودگي ناشي از گازوئيل بر فرسايش‌پذيري خاك‌هاي غني از آهك در حاشيه انبار نفت همدان با استفاده از دستگاه شبيه‌ساز باران

Investigation of Gasoil Contamination Effect on the Erodibility of Soils Rich- lime Around the Hamedan Oil Storage using Rainfall Simulator

.آلودگي خاك‌ها با هر كدام از فرآورده‌هاي نفتي باعث تغيير در ويژگي‌هاي زمين‌شناسي مهندسي خاك‌ها شده و رفتار خاك‌ها را تغيير مي‌دهد. در اين پژوهش به‌منظور بررسي تأثير آلودگي ناشي از گازوييل بر فرسايش‌پذيري خاك‌ها، محدودۀ انبار نفت همدان انتخاب گرديد و به اين منظور از دستگاه شبيه‌ساز باران استفاده شد. براساس نتايج حاصل از بررسي‌هاي صحرايي و آزمايشگاهي، سه لايه خاك در محدودۀ بررسي شده وجود دارد كه مطابق رده‌بندي يونيفايد در ردۀ SM قرار دارند و داراي مقادير بسيار بالاي آهك، يعني 15/85% در لايۀ بالايي، 16/62% در لايۀ مياني و 72/88% در لايۀ پاييني هستند. تعيين ويژگي‌هاي زمين‌شناسي مهندسي نمونه‌ها با انجام آزمايش‌هاي تعيين درصد رطوبت، دانه‌بندي و هيدرومتري، كلسي‌متري، تعيين GS، حدود آتربرگ، تراكم استاندارد، برش مستقيم و مقاومت فشاري تك‌محوري روي نمونه‌هاي غيرآلوده و آلوده به گازوييل انجام شد. براي بررسي اثر ويژگي‌هاي زمين‌شناسي مهندسي نمونه‌هاي غيرآلوده و آلوده به گازوييل بر فرسايش‌پذيري با استفاده از دستگاه شبيه‌ساز باران، از شيب‌هاي 10، 20، 30 و 40 درجه، شدت بارش مشابه با ميانگين شدت بارش منطقه و تراكم خاك با رطوبت بهينه استفاده شد. نتايج به‌دست آمده نشان مي‌دهد كه آلودگي ناشي از گازوييل باعث كاهش مقادير پارامترهاي مقاومتي خاك‌هاي منطقۀ بررسي شده و اين كاهش مقادير پارامترهاي مقاومتي، خود باعث افزايش فرسايش‌پذيري خاك‌هاي آلوده نسبت به خاك‌هاي غيرآلوده شده است. بدين صورت كه حداكثر مقدار فرسايش در سه لايۀ خاك در 19 و 15 درصد گازوييل تقريباً 3 برابر مقدار فرسايش در حالت غيرآلوده است.

In regard to consumptions of oil materials by human, soil contamination causes worriness in environment and geotechnics areas in previous years, such that studying of soils lead to soil refine, soil bearing capacity and soil changing by infiltration of contamination. The rates of problems on environment are different and it depends on soil types and its structure, organic materials values, soil permeability, climate and type of contamination. In viewpoint of geotechnics, many investigations have been done on various contaminated soils that their result leads to optimum application of those as road construction and decrease of costs. In this research, with adding of different percentages of gasoil into the soil, engineering properties of contaminated soils were investigated and its effect on the erodibility of soils was studied. Regarding to the Hamedan oil storages complex extension and lateral installations, the study of contaminated soils are essential. Also, because the location of that complex is at urban area, the environmental risk of leaking of oil materials is available. Thus, the goal of this research is to investigate the erodibility of contaminated soils at the studied area. Material and methods Hamedan oil storages complex is located about 17.7 km far from Hamedan city. In order to study engineering geological properties and erodibility of three layers of soils in studied area, the soil samplings were done from three soil layers. Based on the field and laboratory results, all of three soil layers were classified into SM class and had too much lime (Table 1). Testing program is divided into engineering geological tests and erodibility tests. All of the engineering geological tests on the uncontaminated and contaminated soils were undertaken according to ASTM (2000) (Table 2). In order to prepare the contaminated soils and to determine the maximum absorbable gasoil, the soil samples were contaminated by gasoil and some standard compaction tests were undertaken on the soils. According to the test results, upper and lower layers were saturated by 19% of gasoil and middle layer was saturated by 15% of gasoil. After determination of gasoil saturations percentages for studied soil layers, the 7, 13 and 19 percentages of gasoil were added into the upper and lower layers and the 5, 10 and 15 percentages of gasoil were added into the middle layer. Thus, for engineering geological tests, 9 samples of contaminated soils were prepared.