邹新军,徐洞斌,王亚雄.成层地基中单桩受扭弹塑性分析[J].湖南大学学报:自然科学版,2014,41(9):72~78
成层地基中单桩受扭弹塑性分析
Elastic-plastic Analysis of Torsional Single Pile in Layered Subsoil
  
DOI:
中文关键词:  桩基础  成层地基  扭矩荷载  荷载传递法  双折线模型
英文关键词:pile foundation  layered subsoil  torque load  load transfer method  double broken line model
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作者单位
邹新军,徐洞斌,王亚雄 (湖南大学 土木工程学院湖南 长沙 410082) 
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中文摘要:
      为了探讨成层地基中单桩的受扭性状,基于桩侧土双折线模型,以塑性区开展深度为变量,推导了桩侧土分别处于弹性和塑性状态时桩顶的扭矩扭转角曲线和桩身扭矩、扭转角分布曲线的递推计算方法,并编制出相应的计算程序,由此对比分析了单层与双层地基中桩身的受扭性能.最后,结合工程算例进行了应用,并完成了参数分析.结果表明:考虑桩侧土分别处于弹性和塑性状态所得结果更符合工程实际;桩顶扭矩T一定时,桩顶扭转角φ随桩身材料剪切模量Gp和半径r0的增加而减小;r0对T-φ曲线影响显著,同等条件下r0提高一倍,桩顶抗扭承载力提高4~6倍;可对桩周上部土层进行处理来提高桩身抗扭性能,其有效处理厚度为桩长的0.2倍.
英文摘要:
      In order to discuss the torsional behavior of single pile in layered subsoil, various bearing states (elastic and plastic) of the subsoil were considered, and the double broken line model (i.e., the ideal elastoplastic model) was used to simulate the load transferring law along the pile shaft.The plastic zone developmental depth in the subsoil was chosen as an independent variable to derive the solutions for the torque-twist angle curve at the pile top and the torque-angle distribution curves along the pile shaft in layered subsoil.A recursive algorithm was presented to calculate the torque and the twist angle with the computer program worked out as well.Based on the solutions obtained, the torsional behavior of the pile shaft in the single-layer and the double-layer subsoil was analyzed respectively.Finally, an engineering project was used to verify the present method and to carry out the parameter analysis.The result shows that the consideration of various elastic or plastic states of the subsoil will result in a more reasonable outcome, compared with engineering practice.Furthermore, for a constant torque T, the torsion angles φ at the pile top will decrease with the decrease of the shear modulus Gp and radius r0 of pile shaft.An obvious effect of r0 on the Tφ curve was observed, in which the torsional bearing capacity may be increased 4~6 times if the value of r0 was doubled and other conditions remained unchanged.The upper soil layer may be treated to improve the torsional performance with an advised effective treatment depth of 0.2 times the pile shaft length.
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