钢管复合桩承载特性模型试验研究

为研究钢管复合桩的承载性能,进行了剪力环、泥皮和防腐涂层共同作用下的钢管复合桩和钢筋混凝土桩室内模型试验,对比分析了试件的荷载-变形曲线、钢管变形等参数,并采用分解分析法对钢管复合桩的套箍效应进行了分析.试验及计算结果表明,钢管复合桩承载性能较钢筋混凝土桩显著提高,套箍效应使得钢管复合桩承载力较空钢管和钢筋混凝土桩承载之和提高9.8%,混凝土抗剪强度提高了1.2倍;钢管对核心混凝土产生的紧箍作用沿界面长度增大,且随荷载的增加而增大;在防腐涂层、泥皮和剪力环(间距90 cm)共同作用下,钢管套箍效应带来的混凝土紧箍力最大值可达2.32 MPa;规范ACI (2005)适合于泥皮、防腐涂层和剪力环共同作用时钢管复合桩极限承载力的计算. 

Model Test on Bearing Capacity Characteristics of Steel Tubular Composite Piles

In order to investigate the bearing capacity of steel tubular composite (STC) piles, two groups of piles, including a group of STC piles with shear ring, drilling mud skin and anticorrosion coating and a group of reinforced concrete piles, were used to conduct comparative model tests. The load-deformation curves and steel tube deformations of specimens in the two groups were compared, and the confinement effect of STC piles was analyzed by decomposition analysis method. The test and calculation results show that the bearing capacity of the STC pile was larger than that of the reinforced concrete pile significantly. Due to the confinement effect, the bearing capacity of the STC pile was increased by 9.8%even compared with the sum of the bearing capacity of a hollow steel tube and a reinforced concrete pile;at the same time, the shear strength of the core concrete was increased by 1.2 times. The confining stress of the STC pile increases with load and pile depth. The maximum confining stress of the STC pile with anticorrosion coating, drilling mud skin, and shear ring could reach 2.32 MPa. In addition, the specification ACI (2005) could apply to the ultimate bearing capacity calculation of STC piles with anticorrosion coating, drilling mud skin, and shear ring, in a way to calculate the internal strength.