海上风电大直径超长桩侧阻力抗拔折减系数试验研究

Experimental study on the uplift reduction coefficient of shaft resistance of large diameter and super-long piles for offshore wind turbines

海上风电群桩基础中的单桩需能承受较大的上拔荷载。抗拔承载力往往是决定桩长的控制因素。针对海上风电大直径超长桩的侧阻力抗拔折减系数(抗拔侧阻力/抗压侧阻力)开展研究,通过静载荷试验的方法获得试验桩各土层的抗压侧阻力和抗拔侧阻力实测值,进而得到侧阻力抗拔折减系数,并将其与现行规范推荐值进行对比,验证规范的合理性。研究结果显示,各土层的侧阻力抗拔折减系数几乎都小于规范推荐值。因此,采用规范推荐的侧阻力抗拔折减系数计算大直径超长桩抗拔承载力可能会得到偏危险的结果。

Single pile in pile group foundations for offshore wind turbines must be able to bear extreme uplift loads. Upliftbearing capacity is generally the key factor in designing piles length. We investigated the uplift reduction coefficient of shaftresistance （shaft resistance in tension / shaft resistance in compression） of large diameter and super-long piles for offshorewind turbines, obtained the measured values of compression shaft resistances and uplift shaft resistance in different soil layersby static loading tests, and then obtained the uplift reduction coefficient of shaft resistance, which is compared with therecommended values in the current code to verify the validity of code. The results show that almost all experimental upliftreduction coefficients of shaft resistance of each soil layer are less than that recommended by code. Therefore, it may bedangerous to calculate the uplift bearing capacities of large diameter and super -long piles by using the uplift reductioncoefficients of shaft resistance suggested by code.