Abstract

This study investigated the validity of hydraulic conductivity value using Mini Column Infiltration Test. Granitic residual soils from Broga Selangor, Malaysia were tested to obtain the hydraulic conductivity value in relatively shorter time. Soil samples were physically characterized before being tested using Centrifuge Mini Column Infiltration Technique. A normal 1-g Falling Head Permeability Test (Kf) was also being performed as a comparison with hydraulic conductivity value from Centrifuge Test (Kcen). For centrifuge test (Kcen), there were three factors involved; rotation speed, soil thickness and type of solution (single or mixture solution). Hydraulic conductivity value from Centrifuge Test (Kcen) also was highly depending on the Scale Factor Value (SFV). The results from Centrifuge Test showed that the higher rotation speed, the lower SFV would be. Hydraulic conductivity was decreasing with an increasing of rotation speed. The increment of soil thickness also contributed to the decrement of SFV and hydraulic conductivity value. Thus, the hydraulic conductivity value would be more accurate when higher rotation speed and higher soil thickness were applied. Hydraulic conductivity, Kcen for a single solution also showed higher values compared to mixture solutions. However, some of hydraulic conductivity value (Kcen) showed overestimated values due to the presence of cracks in the soil (mudcakes). Most of the scale factors gave low values (x<1.00) which meant x values were close to unity. The value of hydraulic conductivity for 1-g Permeability Test (Kf) was 2.08×10-6 m/s. While for 10mm soil thickness and 2500 RPM (1440 -g) velocity of a single solution, the value of hydraulic conductivity (Kcen) was 6.82×10-4 m/s. Since the scale factor obtained was less than 1 (x = 0.74), the value of Kcen could be used as a valid number to replace the value of Kf from 1-g Permeability Test. This study concluded that by using scale factor, the relationship between HCV from Centrifuge Tests and Falling Head Permeability Tests could be known; thus, Centrifuge modeling could be developed as a valid method in determining the hydraulic conductivity of the soils.

Highlights

  • Centrifuge modeling has been used over the decades in many aspects to characterize the soil behaviors (Culligan, 1996)

  • Granitic residual soil (BGR) had higher percentages of sand ranged between 54%-63% and according to Unified Soil Classification System (USCS), it was classified as sandy silt material

  • Most of the scale factors were showed to be low values (x

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Summary

Introduction

Centrifuge modeling has been used over the decades in many aspects to characterize the soil behaviors (Culligan, 1996). This method was chosen because of its ability to model complex natural systems in a controlled laboratory environment (Wan Zuhairi and Muchlis, 2012). According to Di Emidio et al (2012; Singh and Gupta, 2002), Centrifuge Test could be used to estimate the hydraulic conductivity of geotechnical materials in accelerated gravity conditions, reproduce the prototype vertical effective. Based on Singh and Gupta (2002), by obtaining the scale factor, the correlation between Kcen and Kf could be identified

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