扩底楔形桩竖向抗拔承载力理论计算方法

Uplift bearing capacity calculation method of belled wedge pile

基于极限平衡原理,建立竖向极限荷载下考虑桩型和土性的含未知参数的统一复合破坏面;根据最大最小值原理,确定破坏面函数中的未知参数及其表达式,从而计算得到极限承载力。通过针对扩底楔形桩和常规扩底桩模型试验结果的对比分析,验证本文所建立理论模型的准确性和可靠性,并分析桩型(如扩大头直径、楔形角等)和桩周土性(如凝聚力、内摩擦角等)等因素对扩底楔形桩竖向抗拔承载力特性的影响规律。研究结果表明,本文所建立的理论计算方法可以简单、有效地计算扩底楔形桩竖向极限抗拔承载力。

Based on the limit equilibrium principle, one unified composite failure surface with unknown parameters under the vertical ultimate load was built, in which pile type and soil parameters were considered. Then the unknown parameters and the function of the composite failure surface expression were determined by the principle of the minimum and maximum values. The ultimate bearing capacity was obtained based on composite failure surface expression. The accuracy and reliability of the theoretical model built in this paper was verified by comparing with model test results. Then, influence pile parameters （such as, enlarged pile base, and taper angle, etc.） and soil parameters （such as, cohesion, and internal friction angle, etc.） analyze were carried out. The research results show that the ultimate pullout capacity of belled wedge pile can be calculated by the established theoretical calculation method effectively.