Soil suction profile due to tree induced suction

Abstract

Suction exerted by the roots water uptake of vegetation can have substantial effects on soil moisture, where it will influence the strength of the soil. However, rainfall pattern is one of the major factors that influence the changes of suction and lead to instability in unsaturated soils. This study discuss an exploration of soil suction is affected by water uptake by tree root at various condition from wet season (high rainfall) to dry season (prolonged no rainfall). The suction at study area are measured using Jet-fill tensiometers and Gypsum moisture block that placed at various depths and distances near vicinity of tree. A total of 18 Jet-fill tensiometers and Gypsum moisture blocks were installed in 6 stations, 3 stations at sloping ground and 3 stations at flat area. Each station consists of 3 Jet-fill tensiometers which at top, middle and bottom of the root zone to monitor the matric suction changes. The results of the soil suction obtained were used as an input data to develop soil suction contour using GID 7.2 software. From analysis of the pattern soil suction profile shown the suction rate is higher at near vicinity of tree and significant increase during dry period. However, a reduction in suction during high rainfall.The effect of tree induces suction will generate high suction in soil and can created dry condition to increase shear strength.