Simulation of Lateral Earth Structure Resting on Gypseous Soil


This study includes the behavior of lateral earth structure constructed on gypseous soil, wherein some cases we are forced to construct such heavy structure over such collapsible soil which may cause severe damages for structures constructed on. To recognize such special case, locally manufactured laboratory model was designed for this study. The model includes, a thick and stiffened in side, rectangular plastic container (800*500*400mm) . The soil used was natural gypseous soil with 5%gypsum content as a reference. an additional gypsum percentages were mixed with the 5% gypseous soil reaches (25%, 40%, and 60%).The gypseous soil was compacted to 18kN/m3 density, placed at lower portion of container. A gravity precast concrete structure was prepared and placed over the collapsible soil. Highly permeable granular soil was placed beside the lateral gravity structure. Dial gauges were fixed at top and beside the lateral concrete structure to investigate the vertical and horizontal deflection of such structures at dry and upon wetting by water from special device manufactured locally, to simulate the rainfall of water from top of model, as in nature.The vertical and horizontal movements of the concrete wall are totally random, that is due to the uneven settlement of wall resting on gypseous soil specially after 24 hour of continuous flooding of water because of fluctuation of water between soil particles and high dissolution of gypsum may have happened after this period due to leaching process and cavity formation below the heavy concrete wall. And so the dangerous from leaching is more than that of soaking of such case.The study includes also the possibility to improve the behavior such structures, by mixing gypseous soil, with 3% cement. The horizontal and vertical movements reduces to more than 25% and 90%, respectively