Location of Solution Channels and Sinkholes at Dam Sites and Backwater Areas by Seismic Methods:Part I -Rock Surface Profiling.

摘要

Sledge hammer seismic refraction surveys and a modified version called downhole shooting are useful for rock surface profiling. Advantages of downhole shooting are calibration at the end points of the survey,measurement of vertical wave propagation velocities directly,and having a refracted wave ray path for almost the entire survey length. The downhole method was simulated with the digital computer. The method can handle any rock surface profile and generates corresponding travel time curves for the forward and reverse profile surveys. This program was used to study the effects of anomalies on the travel time curves. A method of data reduction was developed that enables an estimate of the rock surface profile to be made from the travel time data. Field tests were performed at four sites having soil and rock characteristics different from each other. Rock surface profiles were estimated from the travel time curves using the procedure developed and these were compared with the depth to rock by proof drilling. (Author Modified Abstract)