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Model Tests of a Reinforced Unpaved Road
Civil Engineer, P.O.Box 473, Cote St. Luc, Montreal, H4V 2Z1, Quebec, Canada NorAzazi Zakaria Lecturer, School of Civil Engineering, Universiti Sains Malaysia, Perak Branch Campus, Seri Iskandar, 31750 Tronoh, Perak, Malaysia and Fauziah Ahmad Deputy Dean, School of Civil Engineering, Universiti Sains Malaysia, Perak Branch Campus, Seri Iskandar, 31750 Tronoh, Perak, Malaysia |
ABSTRACT
Organic clays are compressible soils possessing high moisture contents. In Malaysia these types of soils can be found in abundance especially in the state of Perak. The need for constructing a temporary road over these types of soils makes it necessary to investigate the behavior of such soils when subjected to loading.
Accordingly, a research program was devised to study the structural behavior of reinforced unpaved roads constructed over organic soils with geotextiles used as reinforcement. A model test box was constructed especially for this purpose, inside which these tests would take place. The approach adopted in this series of tests was a simple one consisting of monotonic loading of a subbase-subgrade system at ¼ scale.
Load penetration footing tests were performed with four different geotextiles that vary in their tensile strengths. Each geotextile was tested with two different fill thicknesses namely 50mm and 100mm. The results of the footing test would later be used to assess the accuracy of two existing analytical models; Burd’s and Love’s analytical models. These models are used for the design of unpaved roads over reinforced soil.
It was found that the analytical models given by Burd and Love overestimate the reinforced system’s stiffness. It has also been observed that the bearing capacity of the soil increases with the increase of the geosynthetic tensile strength, which seems to be the dominating factor. Other parameters such as moisture content, shear strength and organic content seem to be of minor importance.
Keywords: Organic clays, reinforced unpaved roads, footing tests, geosynthetics
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