EXPERIMENTAL STUDY ON PERFORMANCE OF MULTI-TIERED GEO￣GRID REINFORCED SOIL RETAINING WALL UNDER UNIFORM STATIC LOAD

The characteristics of deformation and mechanical performance of multi-tiered geogrid reinforced soil retaining wall(MGRSRW)need to be further analyzed in detail. In this paper, the model tests are carried out to comprehensively investigate the effect of offset distance, reinforcement length of upper wall and reinforcement spacing on the performance of MGRSRW. The experiments results show that reducing the width of offset distance from 1.3H₁ to 0.4H₁, decreasing the reinforcement spacing or increasing reinforcement length of upper wall, can cause to reduce settlement or settlement ratio on the top of MGRSRW obviously. At the same time, the ultimate bearing capacity of the retaining wall is enhanced significantly. The horizontal deformation of MGRSRW is closely related with offset distance and reinforcement length of upper wall. The distribution of upper wall is tended to be with "drum belly" in the middle of upper wall, and the deformation of lower wall along the wall gradually increases. With the increase of offset distance and decrease of spacing, the vertical earth pressure at the bottom of upper wall increases and the vertical earth pressure near the facing panels of lower wall decreases obviously. Increasing the length of the upper wall reinforcement and reducing the reinforcement spacing can cause to the vertical earth pressure developing away from the wall side. The slip surface of MGRSRW starts at back edge of the loading plate and passes through the bearing pad of toe of upper wall, and then penetrates the soil at the top of the lower wall. The failure mode is dominant in deep sliding failure of the upper wall.