Effect of Rock Fragments on Engineering And Physical Behaviors of Clay Soils

Soils that contain rock fragments are widely distributed throughout the study area (Semel and Bakoz sites).Albeit, this component imposes profound effects on soil physical and engineering properties, its role is sporadically researched and there is contrasting response to this component.Consequently, the current study was proposed to quantitatively describe compressibility, water transport and water retention of soil rock mixtures prepared from two background clay soils and rock fragments of different rock characteristics in form of repacked soil columns or specimens.The results indicated that an increase in rock fragment content resulted in a decrease in soil void ratio and consequently caused a reduction in compression index.This parameter also tended to decrease with an increase in rock strength.It was also noticed that there is a fluctuating increasing trend in saturated hydraulic conductivity to a critical level of soil rock content.On the other hand, it was revealed that the rock fragment size had not an obvious effect on the values of the saturated hydraulic conductivity.Additionally, the results indicated at a fixed suction there is a steady decrease in retained amount of water with an increase in rock fragment contents from 0% to 50% regardless of the rock size.Furthermore, the ratio of transmitting pore to non-transmitting pores and that of macrospores to the sum of mesopores and microspores tended to increase with an increase in rock fragment to a certain limit.