Using georadar as a dam pore water pressure measurement — case study of Sutami Dam

Abstract

The piezometer is used to measure pore water pressure in the dam's core and placed in the upstream and downstream where if the upstream is higher than the downstream, the dam is in good condition. The piezometer measures pore water pressure based on the water levels above itself. This water level is known as a water table. This study determines the feasibility of georadar in finding pore water pressure. As a case study, this study was conducted at the Sutami dam, which has well-functioning piezometers. Measurements are made by the B-scan method at the location above the piezometer in the middle of the dam using the 90 MHz georadar. The radargram from the georadar is then analyzed in two steps, (1) determining the permittivity based on piezometer at upstream, and (2) calculating the water table at downstream based on the permittivity in the first step and comparing the result with the actual value from piezometer. The result shows that georadar can measure pore-water pressure with high accuracy.