Radhey Sharma

Large-Scale Model Footing Tests on Geogrid-Reinforced Foundation and Marginal Embankment Soils

This paper aims at investigating the behavior of foundations on geogrid-reinforced silty clay marginal embankment soil. For this purpose, a total of six large-scale field tests were conducted using a reinforced concrete model footing with dimensions of 457 mm by 457 mm. The parameters investigated in this study included the number of reinforcement layers, the vertical spacing between layers, and the tensile modulus of reinforcement. The effect of reinforcement on the vertical stress distribution in the soil and the strain distribution along the reinforcement were also investigated. The test results showed that the inclusion of geogrid reinforcements results in increasing the soil’s bearing capacity and reducing the footing settlement. The reinforcement benefits improve with the increase in number and tensile modulus of geogrids and with the decrease in layers’ spacing. The inclusion of reinforcements helps in redistributing the applied load to a wider area. The test results also showed that the developed strain along the geogrids is directly related to the footing settlement.

Laboratory Investigation of Behavior of Foundations on Geosynthetic-Reinforced Clayey Soil

The behavior of foundations on geosynthetic-reinforced clayey soil of low to medium plasticity using laboratory model footing tests was investigated. The model footing was made of a steel plate with dimensions of 152 mm (6 in.) × 152 mm (6 in.). The parameters investigated in this study included the top layer spacing, the number of reinforcement layers, the vertical spacing between layers, and the stiffness and type of reinforcement. The effect of reinforcement on the vertical stress distribution in the clay and the strain distribution along the reinforcement were also investigated. The test results showed that the inclusion of reinforcement could significantly improve the soils bearing capacity and reduce the footing settlement. With three or more layers of reinforcement, the settlement could be reduced by approximately 50% at a relatively medium surface pressure. The geogrids with higher stiffness performed better than geogrids with lower stiffness. The test results also showed that the induced vertical stresses in clay under the center of footing could be appreciably reduced with the inclusion of reinforcement, which would result in reducing the consolidation settlement. Insignificant strain measured in the geogrid beyond its effective length of 6.0B (where B is the footing width) indicated that the geogrid beyond this length provided negligible reinforcement effect.

Laboratory Investigation of the Behavior of Square Footings on Reinforced Crushed Limestone

This research study aims at investigating the behavior of spread footings on reinforced crushed limestone using laboratory model tests. The model tests were conducted inside a steel box with dimensions of 1.5 m (length) × 0.91 m (width) × 0.91 m (height) using a steel plate with dimensions of 152 mm × 152 mm (6 in × 6 in). The parameters investigated in this study include the number of reinforcement layers and the tensile modulus and type of reinforcement. The investigation also evaluated the behavior of reinforced limestone foundations. Because of serviceability requirement in actual foundation application, the test results were evaluated in terms of the bearing capacity ratio (BCR) at limit settlement levels and the settlement reduction factor (SRF) at different surface pressures. The test results showed that the inclusion of reinforcement can appreciably improve the soils bearing capacity up to a factor of 2.85 at a settlement ratio of 10% and reduce the footing settlement up to 75% at a surface pressure of 5500 kPa (798 psi). It was also observed that an increase in number of reinforcement layers increases the bearing capacity and reduces the settlement. The results also showed that reinforcements with higher tensile modulus performed better than reinforcements with lower tensile modulus, and that steel reinforcement performed better than geosynthetic reinforcement.

Laboratory Investigation and Analytical Solution to the Behavior of Foundations on Geosynthetic Reinforced Sands

This research investigates the behavior of a geosynthetic reinforced sandy soil foundation using laboratory model footing tests. The model footings were steel plates with dimensions of 152 mm × 152 mm. The parameters investigated in this study included top layer spacing, number of reinforcement layers, vertical spacing between layers, tensile modulus and type of reinforcement, and embedment depth. The test results showed that the inclusion of reinforcement can appreciably improve the soil’s bearing capacity. Higher tensile modulus geosynthetics performed better than others; and that sand reinforced by the composite of geogrid and geotextile performed better than those reinforced by geogrid or geotextile alone. The test results also showed that the reinforcement configuration/layout has a very significant effect on the bearing capacity of reinforced foundation. The results of the model footing tests were compared with the analytical solution developed by the authors in a previous study. The analytical solution gave a good predication of the experimental results of footing on geosynthetic reinforced sand.