Coefficient of at-rest earth pressure from limited backfill

Based on the concept of mobilized angle of internal friction, the coefficient of at-rest earth pressure from limited coarse backfill Κ₀  is obtained after the analysis of the Mohr's cycle. A comparison is made with Jaky's formula for half infinite soil mass Κ_0J and active earth pressure from limited backfill Κ_a. It is found that Κ₀ is close to or smaller than Κ_0J, when the internal friction angle between the rock face and backfill δ_r is equal to that of backfill Ф.  Κ₀ is not only influenced by Ф and inclination of the rock face, but also by δ_r ; Κ₀ may be larger or smaller than Κ_0J, when δ_r is smaller than Ф ; Κ₀ and Κ_a decrease with the increase of the inclination of the rock slop; and Κ₀ is larger than Κ_a. To make the rock face rough and to adopt bench excavation are both effective methods to reduce the at-rest earth pressure from the limited backfill. A design graph is given at the end of the paper.