ارزيابي تاثير مكش بافتي، درجه ي اشباع و تراكم نسبي بر روي مقاومت برشي و رفتار مكانيكي خاك هاي ماسه يي رس دار غيراشباع

THE EFFECT OF MATRIX SUCTION, DEGREE OF SATURATION AND RELATIVE COMPACTION ON THE SHEAR STRENGTH AND MECHANICAL BEHAVIOR OF UNSATURATED CLAYEY SAND

In this paper, a laboratory study on the influence of matrix suction, degree of saturation and relative com¬paction on the shear strength and mechanical behaviour of clayey-sand is presented. For this purpose, triaxial tests under saturated and unsaturated conditions have been carried out. Saturated triaxial tests were oper¬ated in two groups with different relative compactions in consolidated-drained and consolidated-undrained situa¬tions at effective consolidation pressures of 50, 100 and 200 kpa. Unsaturated tests were carried out with an unsaturated triaxial apparatus built at the University of Tarbiat Modares. These unsaturated triaxial tests were operated under a constant water content condition in two groups with different relative compactions at ini¬tial matrix suctions of 30, 100 and 150 kpa, and effec¬tive consolidation pressures of 50, 100 and 200 kpa, An axis translation technique and a double-walled triaxial cell have been used to measure soil matrix suction and variation of pore air volume. Based on the results, the effect of matrix suction, degree of saturation, relative compaction and consolidation pressures on variations of pore air and water volume, and pressures of soil spec¬imens, have been studied. In addition, the mechanical behaviour of the soil is studied by using stress state vari¬ables, and the shear failure parameters have been calcu¬lated.