Measured and Predicted Response of a Post-grouted Pile in Cohesionless Soil

Although compaction grouting beneath the pile tips has been proven to improve the vertically loaded capacity of piles, its design is still largely based on empirical experience and lack of rational design guide. An analytical model that relates the tip resistance to the pressure to expand a spherical cavity for prediction of pile tip bearing capacity is presented. The proposed approach prediction matches quite well with tests results. However, more tests should be done to confirm the correctness of this method. In this paper, a new laboratory setup for investigating the effect of compaction grouting on pile capacity was designed and assembled. This apparatus allows a model pile to be driven into or buried in the sand sample and then a low mobility grout is delivered through a grouting tube inside the model pile into a membrane that is used to prevent grout fracture the sand sample. Then soil stress and pore pressure change are monitored by soil pressure and pore pressure transducer buried in the sample. Pile load test is conducted after the grout have been cured and the pile penetration resistance is measured by the load cell.