Deconfinement Level Assessment for Open-face Tunneling, Part 2

In part two, we will adopt the same tunnel problem but in PLAXIS 2D, and work on to optimize the analytical results through the calibration of deconfinement levels, against several criterion from both deformation and structural response.

Estimation of the support required to stabilize a tunnel excavation, especially in the vicinity of the face, is essentially a four-dimensional problem. Time-dependent weakening of the rock will compound the three-dimensional redistribution of forces around the excavation. Given these constraints, it is valuable to have a general but still relatively simplified appreciation of the nature of the interaction between the rock-mass and the installed support. The Convergence-Confinement method is a basic and commonly used tool for underground support structures in conventional tunneling during the preliminary stage of design. It was initially an analytical method for circular tunnels. Based on the analysis of stresses and strains around a tunnel, the Convergence-Confinement method provides an insight into the interaction between the support and the ground by means of a plane-strain model of the tunnel excavation. It provides meaningful numerical results in a 2D analysis framework.

Prerequisites: PLAXIS 2D installed

Duration: 2 hours

Experience level: Advanced

Presented By: Xing-Cheng Lin