Laboratory investigation into the performance of rock socketed piles in synthetic weak rocks

Abstract

A series of laboratory experiments on small scale rock socketed concrete micro-piles were made to investigate the reliability of published empirical relationships between the strength of the rock and the capacity of the rock to take the pile load. These model piles were axially loaded and socketed into synthetic rock, the properties of which were chosen to simulate weak rock. The values of the strain were recorded to obtain the distribution at different elevations within the pile. The side shear resistance and the base resistance were determined in these experiments. The prediction of the shaft resistance from the rock and the pile properties is a complex problem. The current methods are empirically related to the unconfined compressive strength of the rock mass (qr). Difficulties were experienced in developing the model rock socket pile experiments to obtain the required information. But it is not possible to make definitive conclusions due to difficulties with the experiments; however, the results do indicate that the adhesion factor was about 0.6 in the rough socket, whereas in smooth socket the adhesion factor was about 0.22. The relationship between maximum end bearing resistance, and the unconfined compressive strength, varied between 1.5 to 5.5 time's unconfined compressive strength