Experimental and Analytical studies of 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 include the number of reinforcement layers and the tensile modulus and type of reinforcement. An analytical solution is also developed to estimate the ultimate bearing capacity of reinforced crushed limestone. The test results show that the inclusion of reinforcement can appreciably improve the bearing capacity of crushed limestone up to a factor of 2.85 at a settlement ratio of 10% and reduce the footing settlement down to 75% at a surface pressure of 5500 kPa. The results also demonstrate that reinforcements with higher tensile modulus performed better than reinforcements with lower tensile modulus and that steel reinforcement performed better than geogrid reinforcement. The proposed analytical solution gave a good predication of experimental results of geogrid reinforced sections, while Huang and Menq's solution (1997) gave a good predication for steel reinforced crushed limestone. The analytical results also showed that the reinforced ratio (R_r) should be high enough to form the “deep footing” effect.