SOIL-WATER CHARACTERISTIC CURVE (SWCC) AND PERMEABILITY FUNCTION OF COMPACTED SHALE FROM JATILUHUR FORMATION AT CISOMANG AREA

• Main Author: Muhlisah, Nurul
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/46313
• Institution: Institut Teknologi Bandung

Cisomang is one of the areas traversed by the Jakarta-Bandung transportation infrastructure development project, some places in this area is in the Jatiluhur Formation and have soil characteristics that are dominated by shale. Shale has special characteristic that will experience a shear strength degradation over time, especially if exposed to air after being dug up. Shear strength degradation are exacerbated by drying-wetting process. The drying-wetting process is affected by the hydraulic properties of the soil in both saturated and unsaturated conditions. Under saturated conditions, soil hydraulic property is the saturated water content and the saturated permeability. Under unsaturated conditions, soil hydraulic properties are soil-water characteristic curve (SWCC) and soil permeability function. As part of understanding shale behavior in the Cisomang area, it is necessary to know the soil-water characteristic curve (SWCC) and permeability function of shale in the Cisomang area. This research used filter paper method (filter paper) to obtain SWCC, which is a gravimetric water content versus matric suction. SWCC measurement with filter paper method is done by attaching filter paper to the soil for a certain duration. During this duration, the balancing process will occur so that, the matric suction on the filter paper will be the same as the matric suction on the ground. Shrinkage test is performed to obtain a shrinkage curve. Shrinkage curve along with the results of filter paper test will produce the SWCC. Saturated permeability is obtained from flexible wall permeameter test. Permeability function is calculated indirectly by Fredlund and Rahardjo method (1993) using SWCC and saturated permeability. After filter paper test and soil shrinkage test had been done, SWCC was plotted in three plots: (i) SWCC in gravimetric water content of matric suction; (ii) SWCC in volumetric water content to matric suction, and (iii) SWCC in degree of saturation with matric suction. The shrinkage curve shows that the shrinkage limit is wGs 0.39. These three SWCC plots form a curved curve from the smallest to the largest matric suction. Fredlund and Xing (1994) fitting curve parameters are: (i) For SWCC in gravimetric water content of matric suction: a = 4,81 × 1010, n = 0,502, m = 3785,07 where the air-entry value (AEV) is 750 kPa and the slope of the curve is 13.81% kPa; (ii) SWCC in volumetric water content to matric suction: a = 1,16 × 104, n = 0,86, m = 1,73, with an air-entry value (AEV) of 1600 kPa with a slope of a curve of 0,08 kPa-1 and (iii) SWCC in degree of saturation of the matric suction: a = 1,05 × 104, n = 4,03 and m = 0,31 where the air-entry value (AEV) is 6900 kPa and the slope of the curve is 71,44 %kPa. From flexible wall permeameter test, the saturated permeability (ks) obtained is 2,09 × 10-9 m/sec. In permeability function the permeability values vary from the value of saturated permeability (ks) of 2,1 × 10-9 m/sec and decreases to 8,4 × 10-15 m/sec with increasing matric suction value.