ABSTRACT
Cross-hole and between-gallery seismic work has been performed for many years at major dam projects, particularly at the sites of arch dams, where the deformation moduli of the rock foundation and valley walls are of most concern. Unfortunately, the large number of dams constructed from the 1960s to the early 1980s did not have the benefit of tomographic imaging, in which not just the average velocity between source and receiver, but also the approximate location and velocity could be displayed, following inversion of the multi-source-multireceiver-position data. The use of pairs of boreholes (or multiple holes), for direct access to a ‘hidden plane’ (or planes), on which representative velocities and their location could be calculated has many advantages for assessing the severity of fault zones, the need for treatment of the ground, or even in some cases the avoidance of bad ground. In this chapter, a wide variety of cross-hole seismic tomographic imaging of the sub-surface will be reviewed, from tunnels and caverns, to mining pillars, blasting-effect analysis, excavation disturbed zone mapping, and analysis of grouting efficiency.
