where [[sigma].sub.v,r] is the average vertical stress on the reinforcement strip; [H.sub.c] is the critical height, [H.sub.c] = s/2 for H [greater than or equal to] s/2, [H.sub.c] = H for H < s/2; [K.sub.p] is the coefficient of passive earth pressure, [K.sub.p] = 1+ sin[phi]/1 - sin[phi].

s is the pile spacing (1.8 m); [s.sub.d] is the diagnose pile spacing (2.55 m); d is the pile diameter (0.5 m); [C.sub.c] is the arching coefficient; [gamma] is the unit weight of the fill material (19 kN/[m.sup.3]); [[alpha].sub.0] is the angle of load diffusion in geosynthetic reinforcement and fill for the Nordic method; [K.sub.g] is the tensile stiffness of the geogrid (1600 kN/m); k is the ground reaction modulus; [[phi]'.sub.k] is the fill material internal friction angle (35 degrees); SSA is the semispherical arch; [K.sub.p] is the passive earth pressure coefficient.

Again, it emphasizes that the wall movement velocity has no significant effect on the magnitudes of passive earth pressure. It is worth mentioning that in a specific wall rotation, [e.g.

Figure 11 depicts the induced lateral passive earth pressure on the face of the wall for the numerical and laboratory test models.

Passive earth pressure with critical state concept, Journal of Geotechnical and Geo-environmental Engineering 128(8): 651-659.

Experimental and theoretical investigations of a passive earth pressure problem, Journal of Geotechnique 20(1): 17-37.

Furthermore, illustrated in Figure 11 is the comparison among the computed passive earth pressures from the numerical model and the captured data from the laboratory model just for the wall movement velocity of v = 0.075 mm/s (the first cycle).

However, in passive condition, the failure wedge was considered triangular similar to the conventional M-O method, though this assumption causes the passive earth pressure to be overestimated.

Ebeling, "Limit equilibrium computation of dynamic passive earth pressure," Canadian Geotechnical Journal, vol.32, pp.481-487, 1995.

Kumar, "Seismic passive earth pressure coefficients for sands," Canadian Geotechnical Journal, vol.38, pp.876-881,2001.

Active earth pressure generated in each individual cell is resisted by an equivalent

passive earth pressure generated by the adjoining cells.

where [M.sub.Q] is the moment of the

passive earth pressure and [p.sub.2] = q[cot.sup.2]([alpha]) is the active earth pressure.