Ge-29 study of osmotic tensiometer for measurement of soil suction and assessment of slope stability

• Main Author: Kumaarr, Prabhuram Sujith
• Other Authors: Harianto Rahardjo
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Civil engineering
• Online Access: https://hdl.handle.net/10356/148974
• Institution: Nanyang Technological University

Soil is broadly categorised into either saturated soil or unsaturated soil. While the former is identifiable by voids which are filled exclusively by water, its unsaturated counterpart has voids that are fully filled by a characteristic mixture of both air and water. Soil suction in unsaturated soils has two parts to it: matric suction and osmotic suction. Matric suction is stated as the difference between the pore-air pressure and the pore-water pressure arising from the soil particles' capillarity on pore-water. Osmotic pressure refers to salts present in the soil’s pore water. As a combination of factors, the unsaturated nature of the soil, negative pore-water pressure, and matric suction affect the soil’s shear strength and slope stability. Conventional techniques were used derive soil-water characteristic curves (SWCC), an important property of a soil that depicts the correlation between the soil’s water content and matric suction. These techniques include tests conducted using Tempe cell and pressure plate. WP4C Dewpoint Potentiometer is a lab-based device used to measure high suction values, which can provide data for the SWCC for greater suction ranges. This report describes the analysis of SWCC and slope stability using numerical modelling for Sembawang Road soil at 3-5m depth. The main focus will be on investigating the efficiency and accuracy of the osmotic tensiometer, a device that employs water-absorbent polymer hydrogel to measure suction higher than 100kPa, as compared to the conventional tensiometers.