Experimental investigations of earth pressure on a retaining wall

Conclusions

• 1. The large-scale investigations showed that when a retaining wall can yield away from the backfill the magnitude of lateral earth pressure is determined with sufficient accuracy by Coulomb's equations. The intensity of the vertical stress in soil near the walls is, according to the experimental results, by a factor of 1.5–2 less than that determined by the formula σ=γh. In these conditions the coefficients K₁ and K₂ vary within comparatively small limits over the wall height.

• 2. The development of earth pressure on more stable walls differs from that described above. At a backfill height of 4.25 m the intensity of the lateral pressure near the base is close to that determined by the equation for the active state of soil behind the wall. However, in the upper and middle parts of the backfill the stresses appreciably exceed those calculated. Just as in the first case, the intensity of the vertical component of pressure is below that calculated. The coefficient K₁ and K₂ in this case are variables: they are smaller in the lower layers of the backfill (0.4–0.6) and larger (1.2–1.6) in the upper parts.