钢管复合桩粘结-滑移性能研究

Bond-Slip Performance of Steel Tubular Composite Piles

为研究内置剪力环、泥皮和防腐涂层的钢管复合桩的粘结-滑移性能,假定钢管复合桩粘结应力沿界面呈指数变化规律,提出了一种新的钢管复合桩粘结-滑移本构理论分析模型.依托港珠澳大桥建设,开展了5组钢管复合桩推出试验(其中2组试件设有剪力环),验证了本文模型的正确性.试验结果表明:在外荷载作用下,钢管与混凝土粘结滑移和钢管应力理论计算结果与实验结果基本吻合;粘结破坏时钢管于核心混凝土相对滑移量均小于0.2 mm,泥皮和防腐涂层降低了钢管与核心混凝土之间的粘结;在剪力环间距为1D(D为桩径)的条件下,剪力环使钢管复合桩的粘结强度提高约50%,泥皮和防腐涂层对钢管复合桩的弱化效应可不计.钢管复合桩粘结应力沿界面基本呈指数规律变化.

To investigate the bond-slip performance of steel tubular composite （STC） piles with shear ring, drilling mud skin and anti-corrosion coating, a new bond-slip constitutive model of the STC piles was proposed assuming an exponential trend of adhesion stress along the length of interface. The correctness of the model was then verified using five push-out tests of STC piles conducted in construction of the Hong Kong-Zhuhai-Macao Bridge, among which two tests adopted pile samples with shear ring. Results showed that under the external load the theoretical predictions of the bond-slip displacement between steel tube and concrete and the stress of steel pipes were consistent with the experimental results. The relative slip displacement between steel tube and concrete was less than 0. 2 mm when the failure of piles was induced by the bond-slip behavior. The adhesion stress between the steel tubes and concrete was reduced by drilling mud skin and anti-corrosion coating. The average bond strength of STC piles was increased by 50% because of the shear ring when the spacing of shear ring was ID （where D is the diameter of the pile） , while adverse effects of drilling mud skin and anti-corrosion coating would be ignored under this condition. In addition, the exponential relationshipbetween adhesion stress and the length of interface was observed.