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For open-ended jacked pipe pile, the pile body is subjected to complex forces during pile jacking, especially the soil plug resistance caused by soil plug effect inside the pile body, which has a significant influence on the pile side resistance. Therefore, it is of great significance to carry out a comprehensive experimental study on the mechanical mechanism of jacked pile and the side resistance separation of open-ended pipe pile for the construction and bearing capacity determination of jacked pile. The influence of the pile end form on the pile penetration mechanism in the homogeneous cohesive soil layer was discussed by means of laboratory model tests. Based on the development of the double-wall open-ended model pipe pile, and combining utilization of sensitized fiber Bragg grating strain sensor and double-diaphragm temperature-self-compensating fiber Bragg grating earth pressure sensor, the "soil plug resistance" implied in the pile jacking resistance was separated, and the variation rules of axial force and pile jacking resistance of the pile during the penetration of open-ended pipe pile were obtained. The test results showed that the different pile end forms not only affected the development of pile end resistance, but also had a significant influence on pile side resistance. With the increase of depth, the axial force of the close-ended pile decreased continuously, and the decline rate of axial force acting on the open-ended pile far from the pile end increased gradually, and the axial force near the pile top was basically 0. The unit pile side resistance continued to increase with depth, and the degree of unit pile side resistance of the open-ended pile external pipe pile body was less than that of the close-ended pile. At the same depth, with the increase of penetration depth, the unit pile side resistance decreased continuously, i.e., the phenomenon of "side resistance degradation". Moreover, with the increase of penetration depth, the unit pile side resistance at this position decreased more, which was consistent with the existing research conclusions on the mechanical properties of jacked pile penetration. The research results can provide references for the construction design of jacked pile in cohesive soil. [ABSTRACT FROM AUTHOR]

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]