STUDY CONSTITUTIVE SURFACE PREDICTION OF VOLUME CHANGE FOR SATURATED-UNSATURATED COMPACTED SPECIMEN ON HIGH NET NORMAL STRESS SHALE CISOMANG

• Main Author: Muhammad Tanjung, Mahadhir
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70978
• Institution: Institut Teknologi Bandung

Volume change is one of the important domains of analysis in geotechnical engineering. Volume changes are caused by the occurrence of a swelling-shrinkage process in the soil due to the wetting-drying cycle in the field which is influenced by weather/climate change. Changes in volume cause damage to a building, for example, the occurrence of settlement and heaving. The wetting-drying cycle that occurs in the field can be explained by the concept of unsaturated soil mechanics through the Soil Water Characteristic Curve (SWCC) chart which represents variations in the moisture content in the soil layer to the matric suction value. This study aims to describe 3D graphs of the prediction of the volume change constitutive surface under saturated-unsaturated conditions using shale samples obtained from the Cisomang area, Purwakarta Regency, West Java. Shale is known to have high swelling-shrink potential and is a special material that needs to be characterized. The 3D graphical depiction of the prediction of the volume change constitutive surface is carried out by combining the consolidation test data net normal stress (?-ua) vs void ratio (e) with SWCC data of water content (w) vs matric suction (ua-uw). Prepare the shale test specimens by crushing the shale, then the shale that passes the sieve number 20 compacted by compacting according to ASTM D-1157 . Consolidation test according to ASTM D-2435 is carried out with a maximum stress of 5000 kPa. Additional tests were carried out, namely Swelling test method A, and Swelling test method C according to ASTM D-4546. From the tests carried out, it can be concluded that the Cisomang shale has the potential for swelling with a high category and a swelling pressure value of around 300 kPa. Then for SWCC data obtained from previous research by Kamilia, H. N. (2022). The 3D graphical depiction of the prediction of the constitutive surface is carried out using the equation by Ho (1988) by determining the coordinates of the points u, v, w, and x that form 3 planar planes. Where plane I is the consolidation test result data area, plane III is SWCC data, and plane II is the transition between plane I and plane II. The prediction graph of the volume change constitutive surface is illustrated with an arithmetic scale and a logarithmic scale for two parameters that describe volume changes in the mechanical concept of unsaturated soil, namely soil structure phase (e) and water content phase (w).