SPECIAL SONAR TECHNIQUES FOR RECORDING A DETAILED, HIGH RESOLUTION CAVERN GEOMETRY

摘要

As part of the general monitoring of cavern operations and for calculating the current volume, the geometry of a cavern is determined from sections recorded at specific depths. When recording these sections the survey head measures either horizontally or at any required angle of tilt. In each individual section the cavern shape is detected by point measurements made at discrete angular intervals.In addition, for determining the shape in certain parts of caverns special sonar techniques are applied that enable the cavity geometry to be measured with a considerably greater survey point density. The spiral technique, in which the cavern shape is sampled spirally, is applied for instance to measure areas with high accuracy, such as in cavern necks, roof structures and cavity constrictions. Special software has been developed for interpreting and spatially presenting the results of these surveys.Besides carrying out spiral surveys the survey point density can be increased also by reducing the vertical interval between two survey horizons or by using smaller angular intervals when recording a section. If still higher data quality is required sections can be recorded several times and subsequently correlated.In this paper the execution of these special techniques and the interpretation of the results are explained with reference to practical examples and the advantages the techniques provide for solving operational problems are demonstrated.