New passages in old dams

Abstract

A number of new passages have been excavated in existing dams. These penetrations are to improve access, provide new outlets or access for grout curtains, and upgrade dams and outlets to meet modern standards. Potential damage to adjacent grout curtains, waterproofing details or appurtenant facilities from excessive vibration is a major concern. This paper reviews available excavation techniques and considers issues to be addressed for each. Vibration thresholds are also reviewed. Case histories for Klingenberg dam, Spelga dam, San Vicente dam and Warmwithens dam are used to illustrate the discussion of the different techniques.