Shear strength of interface between Swelling clay and Sedimentary rock

Abstract

The stability of jointed rock slopes is almost controlled by the behavior of interface plane between the rock layers. The upper Mokattam plateau cliffs consists of limestone layers intercalated with shale layers. The main objective of the present thesis is to study the shear parameters interface of swelling soil-limestone during swelling process. Two types of swelling soil El-Mokattam shale & Bentonite, and El-Mokattam limestone used in this study. The effect of thickness of limestone layer overlaying swelling soil, activity of swelling soil, and swelling process are taken into consideration on the shear parameters. Swelling properties of soil are obtained from direct and indirect measurement tests, and shear behavior of swelling soil investigated in this thesis. The results show that the max. shear stress interface for two types of swelling soil used is less than that for swelling soil in case of dry and max. swelling by about 20-60%.The interface cohesion is less than that for swelling soil by about 33-50% and interface angle of shear resistance is less than that for the angle of shear resistance of swelling soil by about 28-32% in case of dry and max. swelling for the swelling soil used. The max. shear stress interface and the interface shear parameters for two types of swelling soil used decreases as the swelling duration increases. max. shear stress interface increases as the thickness of limestone layer increases for two types of swelling soil used with variable swelling duration.