Abstract: With the continuous innovation of construction equipment and technology, non-displacement rock-socketed prestressed high-strength concrete (PHC) pipe pile has been gradually popularized and applied. To reveal the bearing mechanism of pile toe of rock-socketed PHC pipe pile, five groups of static load destructive tests of pile toe of PHC pipe pile with pile diameter of 500 mm in argillaceous siltstone area were carried out under the background of the drilling with prestressed concrete pipe pile. The bearing capacity and macroscopic failure mode of the pile toe of rock-socketed PHC pipe piles under different conditions were analyzed, and the calculation method of the pile toe bearing capacity was proposed. The test results show that when PHC pipe pile with open pile shoe is used and the pile end is not sealed, the open pile shoe weakens the bearing capacity of pile toe of PHC pipe pile. The pile shoe pierces into the bedrock, and the settlement of the pile toe is 11−15 mm under the ultimate load. After pouring concrete to seal the bottom, the bearing capacity of pile toe is significantly improved. The ultimate bearing capacity is 340% higher than that without bottom sealing, and the pile toe resistance share ratios of bottom sealing concrete and pile shoe are 78% and 22%, respectively. The pile toe is subjected to overall shear failure. Finally, based on the Hoek-Brown strength criterion, a simplified calculation method for the bearing capacity of pile toe of rock-socketed PHC pipe piles is put forward. The calculation accuracy of this method has been verified by the tests, and the calculation method can be used as a reference for the design and construction of non-displacement rock-socketed PHC pipe piles.

Key words: prestressed high-strength concrete (PHC) pipe pile, rock-socketed pile, pile toe, static load test, bearing capacity