عنوان مقاله [English]
نویسنده [English]چکیده [English]
When the metal is in contact with the soil, the possibility of sticking to the metal. This phenomenon is due to the adhesion forces between the soil and the metal. Some manufactures for quantifying the tension stress for separation of metals from soil is designed and studied in letratures.The cone pull-out device is one of them. In this apparatuse, a cone penetrate into the soil, stopping it for a specific time and then separating from the soil. In this divice measure the stress required for soil separation from the metal (tension stress). In the present reserch, according to previous studies and ideas about this subject, cone pull out test device designed and manufactured. With performing 90 tests on a montmorillonite clay soil with different value for stope time and separation speed the effect of these variable was studied. The results showed optimum stope time (t =5 min) and separation speed cone (15 mm / min) is determined. To evaluate the reproducibility of the results, performing other 60 tests on two other kaolinite clay soils, coefficient of variation (13.02 ≥ Cv ≥1.4) and accuracy index (1.22 ≥P≥ 1.01) was determined. Thses values are showed which results repetable and acceptible. Because of the effect of moisture content on the engineering properties of fine-grained soil, the effect of moisture changes on tensile stress for seperation metal from soil was studied. The results of the study showed with increase water content decrease tension stress. Accordingly, linear relationships were proposed between soil moisture content and tensile stress for montmorillonite and kaolinite clay soils. Slope of the curve moisture content versus tension stress for montmorillonite clay soil and kaolinite clay soil is 1.25 and 0.82 respectivly. So It can be concluded that the slope of the curve is related to the soil type and with increase plastic index increase tension stress.