Elastoplastic Analysis of Two-Layered Circular Lining Based on the Unified Strength Theory

Figure 2

The three stress states in a two-layered lining under hydrostatic in situ stresses.

(a) Plastic zone in inner layer (R₀≤ r_p≤ R₁)

(b) Plastic zone in outer layer (R₁≤ r_p≤ R₂)

(c) Plastic zones in both layers (R₀≤ r_p1≤ R₁, R₁≤ r_p2≤ R₂)