The use of transmissivity data from probe holes for predicting tunnel grouting - Analyses of data from the access tunnel to the Aspo Hard Rock Laboratory

Results from hydraulic tests in, probe boreholes in the access tunnel to th e Aspo Hard Rock Laboratory, Sweden, were compared to the amount of perform ed pre-grouting of the tunnel made in order to reduce water inflow. It was found that the probe holes identified the major hydraulic conductors well. Also, parts of the tunnel with very tight rock could be predicted. In the i ntermediate range, the precision of the grouting predictions can be improve d with a probe hole pattern that is better adjusted to the geometry of the conductive fractures. Data for this can be obtained by mapping of orientati on, and trace lengths of the water bearing fractures. (C) 2001 Elsevier Sci ence Ltd. All rights reserved.