Numerical modeling of the effect of geometrical parameters of fractures on penetration rate of TBMin fractured rock mass

Existence of rock fracture is very important in evaluating the penetration rate (PR) of TBM in fractured rock masses. In previous research works, the influence of geometrical properties of a joint set such as joint spacing and orientation on PR has been investigated. Since the actual rock mass is geometrically complex, the hybrid Discrete Fracture Network- Distinct Element Method (DFN-DEM)which is used a closer conceptual modelto the reality (DFN) and facilitated a powerful numerical method (DEM) is used for numerical modeling of PR of TBM in fractured rocks. The DFN models is based on stochastic representation of fracture systems, using the probability density function (PDF) of fracture parameters (e.g. orientation, length) formulated according to field mapping results and generated by Monte Carlo method. Using a number of DFN-DEM models for predicting the penetration rate of TBM, a probabilistic numerical modeling is established. Numerical modeling results show that the PDF of positive incremental chipping area follows the normal distribution with the mean value of 46%. The Probabilistic Cumulative Distribution Function (PCDF) of results shows that the positive incremental chipping areas are greater than 20% and 33% when 95% and 80% are respectively considered.