考虑剪力环、泥皮和防腐涂层作用的钢管复合桩工作性能模型试验研究

依托港珠澳大桥建设,通过5组不同组合的钢管复合桩模型试验,其中2组试件设有剪力环,开展了内置剪力环、泥皮和防腐涂层对钢管复合桩工作性能影响的研究,比较和分析试件的荷载-变形曲线、截面变形规律、钢管与剪力环变形等。试验结果表明,剪力环、泥皮和防腐涂层对钢管复合桩的工作性能具有一定的影响;泥皮和防腐涂层使钢管复合桩的黏结强度降低,而剪力环加强了钢管与核心混凝土的联结,钢管的受力及变形显著增加。在泥皮、防腐涂层和剪力环共同作用下,桩截面变形呈"倒v"或"m"型,不再满足经典力学的平截面变形假定。在泥皮、防腐涂层和剪力环间距S≤2D(D为桩径)的条件下,剪力环的嵌固作用可以完全克服泥皮和防腐涂层的不利影响。在试验结果研究的基础上,进一步探讨泥皮、防腐涂层和剪力环不同组合下钢管复合桩的刚度计算问题,并给出了在弹性阶段范围内钢管复合桩刚度计算公式,泥皮(厚度0.1 mm)和防腐涂层使其刚度降低,剪力环则使其增加。其研究结果可为钢管复合桩基工程设计提供重要的参考。

Model test research on work performance of steel tubular composite pile with shear ring,drilling mud skin and anticorrosion coating

To investigate the effects of shear ring, drilling mud skin and anticorrosion coating on performances of steel tubular composite (STC) piles, five model tests with different combinations of shear ring, drilling mud skin and anticorrosion coating are conducted; two of them are with shear ring, relying on the construction of the Hong Kong-Zhuhai-Macao Bridge. The load-deformation curves and deformations of cross-section, steel tube and shear ring have been compared and analyzed. The results obtained from the tests show that the bond strength of STC pile is reduced by drilling mud skin and anticorrosion coating, while the performances of steel tube are improved by shear ring. The cross-section deformation of pile shows "inverted v" or "m" type; it no longer meets section deformation assumption of classical mechanics. The disadvantage effects of drilling mud skin and anticorrosion coating can be completely overcome by the shear ring, when its spacing is less than 2D (D is pile’s diameter). Based on the test results, the stiffness calculation of STC pile has been discussed and the stiffness calculation formula in elastic stage has been given. The stiffness of STC pile is reduced by drilling mud skin with thickness of 0.1 mm and anticorrosion coating, which is improved by shear ring. The paper will provide references for STC pile’s design.