Preliminary Design for NATM Tunnel Support in Soil

The Use of Exploratory Tunnels as a Tool for Scheduling and Cost Estimation

“…With respect to size-strength classifications, graphs are plotted according to point load strength versus block size. The International Society for Rock Mechanics (ISRM) classification includes the following parameters: discontinuous spacing, uniaxial compressive strength, and the angle of friction of fractures [2].…”

Numerical solutions for tunnels excavated in strain-softening rock masses considering a combined support system

“…The process of tunnel advancement and the sequential installation of primary and secondary support systems have been considered. Throughout the analyses, the following assumptions have been made: (1) The surrounding rock is homogeneous and isotropic, and exhibits an elastic-plastic mechanical behaviour. The strain-softening (SS), the elastic-perfectly-plastic (EPP) as well as the elasticbrittle (EB) models are adopted to simulate the post-failure behaviour of rock masses.…”

“…The tunnels supported with a system comprising several supports are in high demand due to the increasing demands of transportation, geological disposal, hydraulic and mining engineering. The primary support system is usually put in place to seal the rock and withstand the loads that may arise during the excavation, while the secondary support system is installed to ensure the long-term stability of tunnels [1][2][3]. Thus, a reliable analysis of the secondary support system constitutes a critical topic to the long-term stability of tunnels.…”

A probabilistic design approach for tunnel supports

“…A simple but effective way of doing this is to use the hyperstatic reaction method (HRM) [9][10][11][12][13][14][15]. This requires the definition of active loads that are applied directly to the support structure by the rock mass; further passive loads are due to the reaction of the rock mass to the displacement of the support structure (interaction between the support structure and the rock mass).…”