Field test on load transfer mechanism of large diameter bored pile embedded in limestone.

In order to investigate the vertical bearing capacity and load transfer characteristics of large diameter bored piles embedded in limestone foundation, the static load test and the internal force test of 6 large diameter rock-socketed piles were conducted based on a project in Jinan. The test results show that the Q-s curves of the test piles P1-P3 were the slow type, the maximum percentage of residual sedimentation in the total sedimentation is 52%. There were obvious elastic working characteristics in the test results, which satisfied the design requirements. Additionally, the test piles P4-P6 occurred "piercing damage" under the ultimate load and the Q-s curve appears a steep descent stage, which means an unreached bearing capacity. Under the maximum load, the side friction of the piles P4-P6 in strong weathering limestone is completely exerted, but the ultimate side friction is lower than the minimum recommended value stipulated in the standard Technical code for building pile foundation (JGJ94-2008). Under the maximum load, the tip resistance of the piles P1-P3 accounts for 23.7%-39.9% of the total load, and the tip resistance of the piles P4-P6 accounts for 38.4%-53.8% of the total load, all piles test results show a portion of the characteristic of end-support friction pile. [ABSTRACT FROM AUTHOR]