Study of the effect of geomembranes on the interaction between the soil and underground structures

Geomembranes are widely used as insulation materials in different civil engineering applications. failure due to the slippage between Geomembranes and the interfacing soils was detected at some cases. this research investigated the factors controlling the developed interface stresses strength between the soil and Geomembranes. in order to quantify the effect of different commonly used isolation membranes on the behavior and stability of buried concrete structures, laboratory studies by using modified direct shear apparatus is performed and integrated and the reduction in the shear resistance between the soil and different types of isolation Geomembranes is determined. graded sand with well-rounded particles was used in the experimental program. shear tests were applied under a normal stress range of about 25-100 KPA. the effect of the Geomembranes on the peak and residual interface shear strengths is highlighted. test’s results indicate development of peak interface shear resistance at a small strain and constant residual interface shear resistance at large strain. it was found that the developed peak and residual interface friction angles between the sand and the Geomembranes interfaces ranged from 59% to 82% of the corresponding angles between sand and un-protected concrete.