Controlling shifts in dams across valleys - by precision distance measurements between dam and fixed terrain points

摘要

The invention provides a more precise and more economic method of effecting measurements to determine the occurrence of slips or displacements in barrages or dams, occurring as a result of the loading and unloading of the dam by water pressure changes. The method consists in making precision distance measurements only between fixed terrain points on the one hand and points on the dam on the other hand. The use of conventional methods of balancing calculations can ensure that the accuracy of the surveying is correspondingly enhanced. Modern devices are available which allow distances over 1 km to be measured with a middle quadratic error of 1.5 + 2d times 10 to the power of minus 6mm, d being the distance in mm.