Effect of Supporting Soil Rigidity on the Apparent Earth Pressure

This paper presents the effect of the base soil stiffness for sandy soils, under a retaining wall on the resulted earth pressure and the wall deformation. The most common method that is widely used in the calculation of the lateral earth pressure on the retaining wall is Rankine theory. This method didn’t take the effect of the base soil stiffness on the value of the earth pressure into consideration. Earth pressure also depends on the value of the wall displacement, which in turns; depends on the wall rigidity. In this study, a set of 2D finite element models were prepared to simulate the effect of retaining wall’s rigidity, different base soil stiffness and the embedded width of the footing inside the backfill on the lateral earth pressure distribution and the maximum bending moment acting on the wall. It is found that the soil base and the wall rigidity are significantly affecting the movement of the wall. The different FE models showed that the wall’s base is rotated and displaced horizontally and vertically due to the backfill weight and the base soil stiffness. Also, the wall rigidity and the rotation of the wall base are affecting the maximum deflection the wall. Due to this movement, the resulted earth pressure is affected by the base soil rigidity and the wall rigidity. In general, Rankine theory is still having a good agreement with the results and has a satisfactory safety factor in most cases.