This paper reports the shear strength and deformation characteristics of compacted residual granite soil. Nine series of tests were conducted using computer control direct shear box apparatus with normal stress level ranging between 0.05 to 0.4 MPa. The influence of moisture content on the shear strength properties is specifically discussed. A relationship between the angle of internal friction and moisture content for residual soil is also proposed. Test results are then used to calculate the non-linear (hyperbolic) model constants and analyse the stress-strain response of the compacted residual soil under direct shear loading. Comparison of numerical predictions and results of direct shear tests are made for verification of the model parameters. It is observed that the predicted stress-strain behaviour using model constants showed fairly reasonable agreement compare to that of the laboratory test results.
In tropical or semi-tropical area compacted residual soil has been widely used as fill material for different geotechnical structures such as road pavements, embankments, retaining structures, land reclamation and landfills. The assessment of the properties and prediction of the behaviour of such fills have often been based on limited information. In spite of various semi-empirical test methods developed to correlate engineering experience, proper design and construction uncertainty still remains. The variation of strength parameters and compressibility of residual soils are mainly caused by differences in moisture contents, which are most likely to occur in such soils. Because of the seasonal variations in rainfall, the degree of saturation changes throughout the year. This results in seasonal variation in strength, which have considerable influence on the geotechnical structures. Still, the failure mechanism, effect of moisture on shear strength, and dilation-contraction behaviour of tropical soil composites are not yet well understood due to limited studies.