Earth pressure coefficient in a vertical backfilled opening

ABSTRACT: A number of analytical solutions have been developed to estimate the stresses in backfilled openings such as retaining walls, silos, trenches and mine stopes. These solutions contain an earth pressure coefficient K, defined as the ratio of the horizontal to vertical effective (principal) stresses. For the case of mine backfilled stopes with immobile rock walls, some researchers proposed to use the Jaky’s at-rest earth pressure coefficient K0 while others proposed to use the Rankine’s active earth pressure coefficient Ka. To clarify this debate issue, the horizontal and vertical stresses at the base of a column were measured for different thicknesses of backfill. The values of K were obtained through the measured stresses. The results show that the value of K is close to the Rankine’s active earth pressure coefficient Ka at the center and the backfill can approach an active state during the placement with even immobile confining walls.