Application of single hole acoustic testing technology in blasting excavation of reservoir dam foundation

Abstract

The quality of dam foundation rock mass is a key factor related to the life cycle and operation safety of the whole reservoir project. Blasting excavation is mostly used for the dam foundation of reservoir dams. In view of the uncontrollable divergence of blasting energy, the rock mass below the foundation surface will inevitably be affected by blasting, resulting in rock mass diseases such as breakage and cracks that are detrimental to structural safety. Therefore, after the blasting excavation of the reservoir dam foundation, it is particularly important to find out the degree and depth of the rock mass below the foundation surface affected by the blasting. The transverse discontinuity of damaged rock mass medium limits the conventional cross-hole ultrasonic nondestructive testing method. At this time, the advantages of the single-hole acoustic testing method and segmented testing technology are prominent. Using the single hole acoustic testing technology, we drill holes within 5 m below the base elevation and carry out the rock mass acoustic testing in sections; the acoustic parameter data of the rock mass in the longitudinal direction along the hole depth are obtained. The data results can reflect the rock mass characteristics in the depth direction of the dam foundation, and the results are reliable, providing a scientific and effective basis for whether to take reinforcement measures for the rock mass of the dam foundation affected by blasting in the next step.