Load distribution behaviour of bored pile in various soil formation: rock socket in limestone, schist and sandstone

Rock socketed bored pile is a solution when the load from the structure is very high and/or accessible bearing surface has an inadequate bearing capacity. The study is based on instrumented bored pile socketing into different types of rock namely. limestone, schist and sandstone at three sites. The result for three (3) test piles namely PTP1, UTP-1 and TP2 shows most of the load are resisted by friction rather than end bearing at the pile working load. The load apportioned to end bearing at higher loads varies for the three test piles. Comparison of observed mobilised skin friction in the rocks with empirical methods indicates that prediction values from Williams and Pells [1] over design for two out of the three test piles and that by Hovarth [2] are under design for two out of the three test piles.