江苏海岸辐射沙洲地层中大直径钢管桩基础承载性能试验研究

Experimental study on the bearing characteristics of steel pipe pile in radial sandbar of Jiangsu province

江苏海岸辐射沙洲是江苏重要的海上风电规划区域,该海域的地层资料和试桩资料极为缺乏。通过钢管桩的现场静荷载试验,对江苏海岸辐射沙洲地层中大直径钢管桩基础承载性能进行研究,以揭示各地层的主要承载性能参数。试桩结果表明,江苏海岸辐射沙洲地层中钢管桩实际的轴向极限承载力明显小于高应变动测结果,只有高应变动测结果的79.09%。总侧摩擦阻力占总承载力的95.61%,而桩端阻力只占总承载力的4.39%。桩内土对管壁的侧摩阻力作用很小,主要是桩外土对管壁的侧摩阻力在发挥作用。辐射沙洲地层中粉土夹粉质黏土的承载性能一般,不适应作为钢管桩的持力层。轴向抗压静载试验得到的极限侧摩阻力高于静力触探的测试结果和API法的计算值。浅部砂层实际的极限水平土体抗力高于API法计算值,在水平荷载作用下上部砂层的p-y曲线具有明显软化效应,土体的软化效应在设计时需进行考虑。

The radial sandbar is an important planning area of offshore wind power in Jiangsu province.Geological data and test results of pile in this area are very few.To reveal the bearing capacity of each layer,the bearing capacity of steel pipe pile in radial sandbar was studied.The test results show that the actual ultimate axial bearing capacity of steel pipe pile in the radial sandbar is lower than that of the high-strain test and the static load test.The ultimate axial bearing capacity accounts for 79.09%of the high-strain test results.The total lateral frictional resistance accounts for 95.61%of the total bearing capacity,while the pile tip resistance accounts for 4.39%of the total bearing capacity.The lateral friction of the soil inside the pile has little effect on the total bearing capacity,but that of soil outside the pile plays a role on it.Layer⑤(silt mixed with silty clay)is not suitable as a holding layer for the steel pipe pile.The ultimate friction resistance resulting from the axial compressive static load test is higher than the results of the static detection test and the results of API.The actual ultimate horizontal resistance of shallow sand is higher than the results of API method.The p-y curve of sand layer in the upper shows an obvious softening effect,which should be considered in design.