Design method for internal stability of multi-tiered geosynthetic-reinforced retaining walls based on limit state

The multi-tiered configuration is often used in the geosynthetic-reinforced soil (GRS) high retaining walls. However, the related design methods are currently lagging behind the engineering practice. The analytical approach to calculate the reinforcement loads of GRS retaining walls is established based on the limit equilibrium method, which is used to determine the load distribution of reinforcement in the limit state, and thus the design method for internal stability of multi-tiered GRS retaining walls is proposed. The parameter analysis is carried out in terms of the reinforcement strength and the reinforcement length required for safe design, and the influences of factors such as offset distance, tier number and height of each tier on the internal stability of retaining walls are revealed. The obtained results show that the required strength and length of reinforcement decrease with the increase of the offset distance, and the required reinforcement strength remains unchanged after exceeding the critical offset distance until the reinforcement length of each tier is completely independent. If the total offset distance is constant, the multi-tiered configuration will significantly reduce the reinforcement strength and length compared with the simple step-slope method. In this situation, the two-tiered configuration yields the least length of reinforcement when the offset distance is large. When the upper wall height is slightly higher than half of the total wall height, the required strength and length of the reinforcement in the two-tiered retaining wall are the smallest.