Test research on factors influencing bearing capacity of rock-socketed piles in karst area

Based on indoor model tests, the research on factors influencing bearing capacity of rock-socketed piles in karst area is carried out. The tests indicate that, with the increases of roof thickness and cave migration position, the ultimate bearing capacity increases gradually; with the increases of cave diameter, equatorial and polar radius, the ultimate bearing capacity decreases gradually. The failure zones are less than 3d range at vertical direction and less than 4d range at horizontal direction. Combined with the model test results, the analysis of influencing factor sensitivities show that, the size order of sensitivities is cave diameter, roof thickness and equatorial radius, polar radius, cave position. The bearing capacity of rock-socketed pile also had relation with cave shape; ratio of thickness to radius is a comprehensive affecting factor with cave thickness, equatorial radius and pile bottom area. The shape factor., bottom area size effect. and notices of conceptual design are introduced to evaluate the bearing capacity of rock-socketed pile, which are verified by engineering examples. The field test results are in agreement with the model test results, and the karst problems not occurred after building completion.