The Evaluation of Trial Grouting on the Foundation Ladongi Maindam, East Kolaka
Grouting (pressurized cement mixture injection) is a frequently used method of repairing the foundation of the main dam. The quality of rock mass is influenced by rock anisotropy conditions, the presence of discontinuities is the main factor that causes permeability, strength, and dynamic rock properties at each location point vertically or laterally. Ladongi Dam is a dam with an embankment type, on the foundation of the main dam is the part that holds the greatest load and also anticipates subsurface flow/seepage, so it is necessary to repair the rock mass on the foundation to increase the strength of the rock mass, and reduce permeability value. 112 lugeon tests were carried out in multiple down stages with a total drilling depth of 560 meters. The spacing and the use of maximum pressure at the time of injection cement are evaluated in this experiment regarding effectiveness and response of rocks to hydraulic fracture and permeability. The test results show that the pattern and pressure applied have been effective for the left abutment and river-bed of the main dam based on all depths in CH-01 and CH-02 that do not require grouting, in contrast to right abutment which still requires grouting in the third and fourth stage CH-03 holes. The left and right abutment show poor conditions at a depth between 10 and 30 meters with a large cement injection volume up to 2000 kg in one stage. The use of many variations of the mixture in the cement mixture injection process indicates a turbulent flow pattern as in the fourth stage of P.RMD 17A. Implementation of grouting can change the natural/initial flow pattern, as in right abutment on the CH-03 almost all flow pattern all stages change to the dilatation pattern based on the relationship of pilot hole and check hole.