Tests on tip status of rock-socketed cast-in-place piles in mountainous geology

The bearing capacity of rock-socketed cast-in-place piles is affected significantly by their tip status. Based on an engineering case, the rock-socketed cast-in-place piles under mountainous geology are tested by using many methods. The judgments of pile tip status are analyzed. An opinion is proposed that the shape and amplitude of low strain reflection wave method are influenced by the strength ratio of concrete-rock and the weight of hammer. At the mean time, a secondary reflection signal with the same phase will be formed on the pile top if there is expanding or opposite phase rock-socketed signal at the half length of the piles, which will confuse the judgment of reflection at the pile tip. Experience of core-drilling test method for judgment of rock-socketed status is introduced. Some suggestions such as camera monitoring footage and backwater near the pile tip are also proposed.