Analytical and experimental approaches to obtain the ultimate strength of reinforced earth elements

Abstract

From the early 1960’s when reinforced earth was introduced by Henri Vidal, much research has been carried out with the aim of estimating the improvement in shear strength of reinforced earth compared to that of unreinforced soil. This paper aims to find the maximum vertical pressure that the soil element can withstand while a lateral pressure is applied to the element. An analytical approach based on the enhanced confining pressure concept as well as some experiments employing triaxial test to determine the ultimate strength of reinforced earth seawalls are proposed. If the soil element is unreinforced, the maximum vertical stress can be easily obtained by multiplying the lateral pressure by the passive pressure coefficient, but for a reinforced element an additional term due to the effects of reinforcement must also be considered. In addition to analytical approach, triaxial tests were performed to examine the behaviour of reinforced and unreinforced sand elements in an undrained fully saturated condition. In conclusion, under low failure pressures (10–20 kPa) the reinforced soil has an internal friction angle higher than that for unreinforced sand, but under higher failure pressures (100 kPa) the internal friction angle of both unreinforced and reinforced sand remains the same.