EVALUATION OF DAM FOUNDATION GROUTABILITY USING SECONDARY PERMEABILITY INDEX AND ROCK QUALITY DESIGN (CASE STUDY IN JLANTAH DAM, INDONESIA)

Abstract

The dam is a building that functions to hold air by blocking the flow of river water. Seepage under the foundation can occur through pores so needs to be cement injection. This research was carried out based on the Secondary Permeability Index (SPI) method in grouting evaluation which still needs to be carried out. The foundation of the Jlantah dam rests on lapilli tuff, agglomerate and volcanic breccia with different characteristics. At this research location there are four relationships between RQD and SPI. Relationship with Type A which shows SPI with Class A to B1 (Very Good to Good) with a low RQD value, caused by the high intensity of interlocking discontinuity areas, and no need for foundation repairs which are rarely found. Type B, which shows RQD is directly proportional to SPI, is found second most frequently. Type C, which shows SPI with Class B2 and C (Fair to Poor) with low RQD due to the high intensity of interlocked discontinuity areas that require cement injection, is the first. Type D shows SPI with Classes C and D (Poor to Very Poor) with high RQD values caused by several faults with the 3rd largest wide opening found.