Numerical modelling for stability of homogeneous clay and sand slopes improved by polyurethane foam piles in slope face

Abstract Polyurethane foam (P.U.) injection resin techniques have been widely used for slab crack repair, soil improvement, and structural crack repair over the past 20 years. In this study, numerical investigations were carried out to enhance the strength of both sand and clay soils via utilizing polyurethane foam as inclusion material. The investigation was conducted using ‘GeoStudio (SLOPE/W) 2D’ software to model 6 m high homogeneous slopes made of soft clay and medium sand with varying slope angles (25°, 30°, 35°) on same soil extended up to 9 m depth and with inclusion of polyurethane foam piles of varying diameter (0.5 m, 0.8 m), length (up to 10 m) and spacing (0.5 m, 1 m, 2 m) in the slope face. The numerical model was verified using experimental test results conducted by Hassona and Abdelnaeem (Physical and mechanical properties of polyurethane foam conditioned sand. MSc, Civil Engineering Department, Faculty of Engineering Minia University). The results revealed that, for slope angle, Ø = 30°, the factor of safety for clay soil increased when using polyurethane piles (diameter, 0.5 m and 10 m length) having spacing of two m, one m, half m, and when used as sheet piles, respectively. The factor of safety for clay soil increased significantly when using polyurethane piles (diameter, 0.8 m, and 10 m length) having spacing the same as before and as sheet piles having width of 0.5 and 0.8 m, respectively. Also, for medium dense sand soil, using polyurethane piles (diameter, 0.5 m and 10 m length) having spacing the same as before, and as sheet piles increased factor of safety much more than that for clay soil. In addition, for medium dense sand soil similar observation were noticed using polyurethane piles (diameter 0.8 m, and 10 m length) having spacing the same as before, and as sheet piles, respectively. In addition, the effects of slope angles also studied.