| Penulis/Author |
FATHAN HANIFI MADA MAHENDRA (1); Ir. I Gde Budi Indrawan, S.T., M.Eng, Ph.D., IPM. (2); Prof. Dr. Ir. Sugeng Sapto Surjono, S.T., M.T., IPU., ASEAN.Eng. (3) |
| Abstrak/Abstract |
The Gedangsari and Ngawen area are predominantly composed of volcanic
and volcaniclastic sequences distributed east-west direction of the northern parts of Southern
Mountain. Massive tectonism and prolonge tropical climate in this region produce
weathering profiles in varying thickness that inevitably affect geotechnical properties.
This study aims to assess the dominant weathering profile of the lower part of the Kebo-
Butak Formation and evaluate the distribution of the discontinuity. In order to know the
dominant weathering profile and discontinuity of the rocks, this study utilizes a total of 26
panels distributed in five stations that investigated the geological condition, weathering
zones, joint distribution, and discontinuity characteristics. The result shows four types
of dominant weathering profiles in the lower part of Kebo-Butak Formation that is dominant
weathering profile A, B, C, and D. Profile A, B, C consists of a relatively identical
weathering degree pattern of fresh, slightly, moderately, completely weathered zone with
the variety of thicknesses. However, the weathering degree in profile D reached the residual
soil degree controlled by more intensive joints. The fine-grained sedimentary rocks
also tend to have smaller spacing, shorter persistence, and higher weathering degree of
discontinuities than coarse-grained sedimentary rocks. |
