海上风电单桩基础的桩长多为50~100 m，比海洋平台桩基的略短，但桩径的大幅增加易导致(超)大桩重的产生。在(超)大桩重的桩基进行沉桩过程中，有必要对其是否发生溜桩进行判别。该研究基于海上风电场单桩基础的实测数据，对风电单桩发生溜桩的影响因素和判别方法进行了探讨。结果表明，大直径单桩在砂-黏交替出现场地容易发生溜桩，当砂层厚度不大于0.2 D (D为桩基直径)，黏土层厚度不小于0.4D时，溜桩风险最大。根据以空腔膨胀理论为基础得到的不同形状物体在土体中运动速度的计算公式，采用现场27根桩的实测数据，得到了计算桩基贯入速度所需要的形状参数; 进一步提出了计算桩基贯入速度的计算流程，获得桩基贯入过程中速度随深度的变化，并据此对溜桩范围进行判别。验证结果表明，该研究构建的判别方法所得结果和工程现场实际测试结果吻合度较高。该研究可为海上风电单桩溜桩判别提供科学的依据。

Objective: Offshore wind turbines (OWTs) are supported by driven open-ended steel piles. At present, monopiles are the most common type of foundation adopted for OWTs because of the simplicity of their design, fabrication, and installation. Compared with the piles used in offshore platforms, monopiles are shorter but heavier. Due to these characteristics, pile drivability analysis needs to be conducted to evaluate whether pile running will occur during pile driving. Methods: Based on the measured data from monopiles of offshore wind farms on site, the influencing factors of pile running are investigated, and the identification methods for pile running are analyzed. This study found that pile running easily occurs when monopiles penetrate areas where sand overlies clay. The thicknesses of the overlying sand layer and underlying clay layer will have an impact on whether pile running occurs. Results: In this study, when the thickness of the sand layer is 0.1D-0.2D (where D is the pile diameter) and the thickness of the clay layer exceeds 0.4D, the risk of pile running is the highest. When pile running occurs, because of the sudden change in bearing capacity, the penetration velocity in the pile running stage will first increase, then gradually decrease, and eventually return to 0. Therefore, the change in penetration velocity can fully demonstrate the process of pile running, and the length of the pile running can be judged based on this. A process for calculating the penetration velocity of the pile during pile driving has been proposed. Based on the process of calculating the penetration velocity, the penetration velocity was calculated. When calculating the penetration velocity during pile driving, the dynamic effect needs to be considered. The method based on the two-dimensional dynamic cavity expansion model was used to calculate the dynamic resistance. The shape parameter N required for calculating the dynamic resistance was obtained using the measured data from 27 monopiles on 3 sites. For a monopile with a diameter of 6.5-9.0 m, the shape parameter N=1.2 is appropriate. Conclusions: A method to determine the length of the pile running, which considers the static and dynamic resistance simultaneously, has been presented. The measurement results on site show that the pile running length obtained by the velocity discrimination method is consistent with that in practice. The identification method for pile running proposed in this study provides a reference for the identification of pile running of similar OWT monopiles in the future.