An Improved Stress and Strain Increment Approaches for Circular Tunnel in Strain-Softening Surrounding Rock Considering Seepage Force

Abstract

Considering the effect of seepage force, a dimensionless approach was introduced to improve the stress and strain increment approach on the stresses and radial displacement around a circular tunnel excavated in a strain-softening generalized Hoek–Brown or Mohr–Coulomb rock mass. The circular tunnel can be simplified as axisymmetric problem, and the plastic zone was divided into a finite number of concentric rings which satisfy the equilibrium and compatibility equations. Increments of stresses and strains for each ring were obtained by solving the equilibrium and compatibility equations. Then, the stresses and displacements in softening zone can be calculated. The correctness and reliability of the proposed approach were performed by the existing solutions.

Stability Analysis of the Surrounding Rock-Lining Structure in Deep-Buried Hydraulic Tunnels Having Seepage Effect

“…Combining Equations ( 11) and (12), and (σ θ p = σ θ e ) r=r p , the plastic zone radius in surrounding rock can be derived as:…”

“…Zhang B Q et al treated the seepage force generated in non-Darcy flow as the body volume and added it to the stress field to derive the elastic-plastic analytical solution based on the unified yield criterion [11]. Wang L et al introduced a dimensionless method to improve the generalized Hoek-Brown (H-B) or M-C criterion considering the seepage effect and concluded the stress/strain incremental calculation method for the elastic-plastic zone of surrounding rock [12]. Du J M et al considered the interaction between the surrounding rock and the lining structure.…”

A Unified Solution for Surrounding Rock of Roadway Considering Seepage, Dilatancy, Strain-Softening and Intermediate Principal Stress

“…For bolted roadway, Gu [10] had analyzed roadway stability in consideration of intermediate principal stress and dilatancy, but seepage effect was not considered; Zhou [22] proposed a new analytical solution with seepage, dilatancy, intermediate principal stress considered, but an elastic-brittle model is used, which is not suitable for describing strain-softening characteristics of surrounding rock without rock bolt or other support measures. Furthermore, scholars [23][24][25][26] obtained numerical solutions for surrounding rock of roadway considering influences of confining pressure and seepage on rock parameters, in which extra relatively complex calculation procedures were needed and not all factors were considered. In conclusion, both analytic and numerical solutions for circular roadway have been extensive studied recently, and the previous literature has analyzed influences of factors including water seepage, strain softening, dilatancy and intermediate principal stress on roadway stability, respectively.…”