A probabilistic design approach for tunnel supports

This paper presents a probabilistic numerical approach for the design of primary tunnel supports, according to the hyperstatic reaction method. This approach considers the probabilistic distributions of the geomechanical index of the rock mass and of the mechanical parameters of the support material, using a Monte-Carlo technique. From the calculation results it is possible to obtain the probabilistic distribution of the support safety factors and then to design the supports on the basis of this probabilistic curve.