Two Dimensional Nonlinear Consolidation Analysis of Saturated Soft Soil Around Tunnel

Abstract

Considering the nonlinear changes of compressibility and permeability of soft soil around the tunnel, a two-dimensional nonlinear seepage consolidation control equation is established, which is solved by an alternating implicit difference method, and the development law of the average degree of consolidation with time under the three conditions of complete permeability, complete impermeability, and semi permeability of the tunnel is obtained. By comparing the degenerate solution with the existing analytical solution, the correctness of the difference solution is verified. In addition, the effects of compression index Cc and permeability index Ck on the consolidation degree of soft soil around the tunnel are analyzed. The results show that the permeability of tunnel is an important factor affecting the development and change of consolidation degree. The influence of compression index Cc on the development of degree of consolidation is less than that of permeability index Ck. Seepage consolidation will change the effective stress field of the soil around the tunnel, and the average degree of consolidation decreases with the increase of permeability index Ck. If the nonlinearity of soil is not considered, there will be a large error in the calculation of degree of consolidation.

Keywords

• nonlinear consolidation
• semi-permeability
• finite difference
• saturated soft soil