Fracture cluster modeling for groundwater inflow prediction into rock tunnels using geostatistics

Groundwater inflows in rock tunnels typically concentrate in narrow zones where conducting fractures cluster together: these concentrations may hamper tunnel advance and are a major source of claims. However, current predictive methodologies do not allow the designer or the contractor to predict these concentrations. The paper describes a geostatistical methodology for the simulation of clusters and fractures in 1D, 2D and 3D. The resulting discrete network of fractures could be used to simulate groundwater flow and predict groundwater inflow into tunnels. The simulation methodology was demonstrated and validated by using data from Pedernales Falls, Yucca Mountain nuclear waste disposal project, and the TBM-excavated South Cobb tunnel project (GA). © 2012 American Society of Civil Engineers.