External seismic stability of vertical geosynthetic-reinforced soil walls using pseudo-static method

Analysis of external stability of vertical geosynthetic- reinforced soil (GRS) walls is very important in the seismic prone zone. The scope of this paper is to obtain required minimum reinforcement length, L-min, for external seismic stability of vertical GRS walls by pseudo-static limit equilibrium method. Then, L-min can be calculated to resist sliding, eccentricity, and bearing capacity failure modes. The parameters considered include both horizontal and vertical seismic coefficients (k(h) and k(v)), surcharge load (q), wall height (H) and the properties of retained backfill, GRS, and foundation soil. Results show that L-min against sliding failure mode, L-min,L-S, increases more quickly than that against the other two failure modes with the increase in k(h), q, or unit weight of retained backfill, gamma(b), while L-min,L-S decreases more quickly than that against the other two failure modes with increase in friction angle of retained backfill, phi(b), or unit weight of GRS, gamma(r). For the different failure modes, the effect of k(v) on L-min is not identical with the change of k(h), and in addition, L-min/H will tend to remain unchanged with the increase in H. In general, L-min against bearing capacity failure mode, L-min,L-BC, is larger than L-min against the other two failure modes. However, L-min,(BC) will be less than L-min against eccentricity failure mode, L-min,L-E, for k(h) exceeding 0.35, or friction angle of foundation soil, phi(f), exceeding 37 degrees, and L-min,L-BC will also be less than L-min,L-S for friction angle of GRS, phi(r), being no more than 26 degrees.