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| Load transfer mechanism and theoretical model of step tapered hollow pile with huge diameter |
| HUANG Ming1，JIANG Song1，XU Dexiang2，DENG Tao1，SHANGGUANG Xing1，3，FANG Tao3 |
(1. College of Civil Engineering，Fuzhou University，Fuzhou，Fujian 350116，China；2. Urban Planning Design Institute of
Ganzhou，Ganzhou，Jiangxi 341000，China；3. School of Civil Engineering and Architecture，East China Jiaotong University，Nanchang，Jiangxi 330013，China) |
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Abstract A new kind of step tapered hollow pile with huge diameter was successfully applied in the stratum with bead-like karst caves. The load transfer mechanism of the pile is complicate. According to the analysis of the load transfer characteristics of the pile，the effect of enhancement of the resistance at variable cross-section to the shaft resistance was revealed. A new load-transfer function model for step tapered hollow pile with huge diameter was proposed on the basis of disturbed state theory. The bearing capacity at variable cross-section was analyzed，and the enhancement effect of shaft resistance caused by the end resistance was presented. An approach for calculating the enhancement coefficient was proposed on the basis of Mindlin?s solution in semi-infinite space. The proposed analytical solution was verified by comparing with the numerical results and two existing analytical solutions. In the new load transfer model，the hyperbolic model and parabola model were selected to describe the relative intact state of pile-soil interface located on the pile side and the pile tip respectively，and Mohr-Coulomb model was used to assume the fully adjusted state. Thus，the load-transfer function model of pile-soil interface was proposed systematically. The effect of the model parameters was analyzed numerically. The proposed calculation model was found to be an excellent to describe the behavior of the step tapped hollow pile with large diameter. The resistance at variable cross-section has a significant enhancement effect on the shaft resistance. The load transfer function model based on the Disturbed State Concept theory can describe the nonlinear，hardening and softening characteristics of pile-soil interface. The enhancement effect of the shaft resistance caused by the resistance at variable cross-section can be revealed obviously.
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2018, Vol. 37 
