Laboratory Based Parametric Study on the Swell Responses in Expansive Vertosols

Abstract

Expansive grey Vertosols are predominant in Australia, especially in Queensland. These soils induce a significant amount of swell strain on the lightweight structures founded on/in these soils when soil moisture changes due to climatic influence. According to AS2870: Residential slab and footing design code (AS2870, 2011) and available literature, active zone depth which contributes to the climate induced-soil displacement in Queensland can be up to 5m. To design lightweight structures founded within the active zone depth, it is imperative to understand swelling behavior of expansive grey Vertosols. The resultant swell strain of these expansive soils is primarily a function of initial water content or initial soil suction and overburden pressure (surcharge). However, there is an extremely limited amount of data available for unsaturated swelling characteristics of expansive soils in Queensland. In this study, a series of conventional oedometer tests were conducted to investigate the effect of the initial water content, initial soil suction and the surcharge on the swelling behavior of expansive grey Vertosol that is predominant in South-East Queensland. The swell strain of expansive grey Vertosol displayed greater sensitivity to surcharge when compared to initial water content or suction. Developed relationship between swell strain per unit change in volumetric water content and surcharge depicted statistically strong (R 2 = 0.89) agreement. The application of the knowledge gathered from this study will benefit the decision making in semi-arid regions when building lightweight structures on grey Vertosol.

A Practical Approach to Determine the Temperature Correction for Ec-5 Moisture Sensors Embedded in Vertosol

“…These investigations include laboratory-based element tests, model tests and field-based investigations. The moisture sensitivity of expansive clays are considerably greater compared to non-reactive soils and hence, much attention has been given to these soils lately [3][4][5][6][7][8][9][10][11][12].…”

“…Expansive soils are widely distributed in arid and semi-arid regions in the world [9][10]. The surface soils in Queensland, Australia consists of more than 40% of these reactive soils.…”

“…The swellshrink characteristics of expansive soils when subjected into alternate wet-dry cycles have caused severe repercussions for the light-weight structures founded on these clays [11][12]. Therefore, the geotechnical practitioners and researchers have identified the importance of the climate-ground interaction in expansive soils and investigated their behaviour under field and laboratory conditions during the past 2 decades [9][10][11][12][13][14][15]. Based on the current research, the variations in soil moisture causes changes in soil suction which eventually results in surface and sub-soil movements in expansive soil strata [9][10][11], [16][17].…”

“…Therefore, the geotechnical practitioners and researchers have identified the importance of the climate-ground interaction in expansive soils and investigated their behaviour under field and laboratory conditions during the past 2 decades [9][10][11][12][13][14][15]. Based on the current research, the variations in soil moisture causes changes in soil suction which eventually results in surface and sub-soil movements in expansive soil strata [9][10][11], [16][17]. Therefore, it is utmost important to determine the changes in soil moisture profile to investigate the expansive soil behaviour under different climatic conditions [9,10,16].…”

“…Based on the current research, the variations in soil moisture causes changes in soil suction which eventually results in surface and sub-soil movements in expansive soil strata [9][10][11], [16][17]. Therefore, it is utmost important to determine the changes in soil moisture profile to investigate the expansive soil behaviour under different climatic conditions [9,10,16].…”