Safety evaluation of the existing Grawan dam based on hydro-geotechnical behaviour conditions to ensure the availability of water resources

Abstract

Grawan Dam was built in 2004 to supply irrigation water and raw water. Lately, the dam has experienced various symptoms of damage to the overflow structure due to hydraulic behaviour and the possibility of overtopping of the dam, which endangers the stability of the dam. Therefore, it is necessary to evaluate the overflow structure system based on the current hydrological conditions and to review the slope stability. In this study an evaluation was carried out covering the safety of the slopes as well as the safety of the overflow building system. Dam slope safety was reviewed based on seepage and slope stability. The stability of the overflow structure security system was evaluated in normal and earthquake conditions. The results of the hydrological analysis on guard height, seepage that occurs safely to permit discharge, and slope stability showed 100% safety from permitted safety factors, and on hydraulic conditions resulted in proposed improvements for Vlugter ponds, transition channels, and energy dampers with planning for Q100, Q1000, and QPMF. Analysis for the stability of the overflow structure showed that it is safe against rolling and sliding, and meets the eccentricity and carrying capacity of the soil, being 100% safe.