单桩基础是海上风电基础中应用范围较广的基础形式,目前工程中在分析桩土相互作用及单桩位移时常采用API规范推荐的p-y曲线模型进行计算。随着桩土理论的不断发展和进步,现有的API规范推荐的p-y曲线模型在应用于大直径桩的分析和计算时,其结果低估了不同深度处土体的极限土抗力,高估了初始地基反力模量,因而降低了计算结果的准确性。该文针对该问题,分析了现有p-y曲线法中影响极限土抗力和初始地基反力模量的因素;通过建立桩土相互作用的有限元数值模型,对不同桩径和土体深度的计算模型进行分析和数据回归,引入修正系数来考虑大直径桩的尺寸效应,并讨论了不同因素影响指数的变化规律,最终建立了适用于大直径单桩基础的修正p-y曲线模型。最后通过与模型试验和现场试验的结果对比,修正后的模型对极限土抗力和初始地基反力模量的计算更加符合实际情况,从而验证了修正p-y曲线模型的可靠性与合理性。
Abstract
Pile foundation is widely used in offshore wind turbines. At present, when the soil structure interactions and the horizontal displacement of pile foundation are analyzed, the p-y curve model recommended by American Petroleum Institute specification is often adopted for calculation. With the development of soil structure theory, when the p-y curve model recommended by the existing API specification is applied to the analysis and calculation of large diameter piles foundation, the results of the ultimate soil resistance at different depths is underestimated and the initial foundation reaction modulus is overestimated, thus the accuracy of calculation is reduced. As to this problem, the factors that affect the ultimate soil resistance and initial foundation reaction modulus in the existing p-y curve model are analyzed in this study. A finite element numerical model of soil structure interactions are established, and the calculation models with different pile diameters and soil depths are discussed and the data regression is carried out. A correction coefficient is introduced to consider the size effect of large diameter pile foundation, and the variation law of influence index of different factors is examined. Finally, a corrected p-y curve model for pile foundation with large diameter is proposed. Compared with the results of model test and field test, the calculation of ultimate soil resistance and initial foundation reaction modulus of the corrected model is more consistent with the actual situation, and the reliability and rationality of the corrected p-y curve model are verified.
关键词
海上风力机 /
桩基础 /
土结相互作用 /
尺寸效应 /
修正p-y曲线
Key words
offshore wind turbines /
pile foundations /
soil structure interactions /
size effect /
corrected p-y curve
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