均质地基中纵截面异形桩受扭弹塑性分析

Torsional Elasto-plastic Analysis of Longitudinal Shaped Pile Embedded in Homogeneous Soil

为了探讨纵截面异形桩的受扭性状,考虑桩身纵向变截面特性,将桩-土体系沿深度方向划分为有限个微元段,建立均质地基中纵截面异形桩受扭弹塑性分析理论模型;基于传统圆形桩桩顶T-φ曲线与桩身扭矩、转角关系曲线,推导获得纵截面异形桩的桩身扭矩和扭转角近似解答,并基于MATLAB编制了相应的计算程序.继而,初步探讨了纵截面异形桩与等截面圆形桩受扭性能的异同点,并开展楔形桩受扭性能影响因素分析.研究结果表明:上端桩身直径对抗扭承载性能影响显著;等体积混凝土用量下,纵截面异形桩的抗扭性能相对优于等截面圆形桩,且楔形桩抗扭性能最优;相同桩顶扭矩荷载下,楔形桩抗扭承载力随桩身剪切模量、桩径、楔角的增加而增大,桩径提高1倍,桩顶抗扭承载力提高3～5倍.

In order to study the torsional behavior of longitudinal special-shaped piles, a longitudinal cross-section pile torsion elasto-plastic analysis model was built in homogeneous soil ground. The model considers variable cross-section of the special-shaped pile, and the pile-soil system along the depth direction is divided into finite segments. Based on the T-φ curve at traditional circular pile top and the torque-angle distribution curves along the pile shaft, the corresponding formula was obtained. The calculation program was run through MATLAB software. The torsional behaviors of longitudinal special-shaped piles and uniform circular piles were comparatively analyzed. The optimum design parameters for tapered pile were analyzed. The results show that the torsional performance is influenced by the top pile diameter obviously. The torsional performances of longitudinal cross-section special-shaped pile are relatively better than those of uniform circular pile with the same concrete usage. The torsional bearing capacity of tapered pile increases with the increase of the shear modulus, diameter, and taper angle, and the torsional bearing capacity is improved to 3~5 times under two times diameter.