Laboratory model study for granular pile with various backfill materials

In this work, laboratory experiments have been carried out to study the bearing capacity ratio which is defined as ratio of the bearing capacity of treated soil with granular pile to the bearing capacity of untreated soil at a given settlement for the foundation. A laboratory setup was used electronic load cell to measure the applied load to the soil-granular pile system and used the displacement transducer to measure the settlement. Granular piles made of crushed stone or gravel or sand with a diameter of 50 mm were installed in very soft clays having undrained shear strength ranging between 13 and 21 kPa. Two ratios of the length to diameter were tried, namely 5.2 and 4. The experimental tests showed that the granular pile using crushed stone as backfill material provided a highest bearing capacity ratio equal to 1.6 and 1.5 for the soil having a shear strength = 13 kPa at the two ratios of length to diameter respectively.