海上风电复合筒型基础粉质黏土下沉试验分析

Analysis of Penetration Test of Composite Bucket Foundations for Offshore Wind Turbines in Silty Clay

复合筒型基础的沉放是一项关键施工过程.沉放时土体在施工负压下受到扰动,土体中土压力和孔隙水压力发生变化,对沉贯阻力造成影响.针对复合筒型基础的沉放过程,在粉质黏土中开展了大比尺模型试验.试验中监测了基础舱内压力、周围土体的土压力及孔隙水压力的变化.通过理论计算,对试验模型沉贯所需负压进行预测,并将试验施加负压与预测负压进行对比.试验结果表明:基础周围土体土压力和孔隙水压力在负压作用下均减小,且筒壁内侧土体土压力减小程度大于外侧土体;沉放过程中基础发生倾斜时,通过向高舱处抽负压可以有效调整基础的倾斜度;预测负压大于试验施加负压,当使用Houlsby提出的计算方法计算筒型基础在粉质黏土中的沉贯阻力时,摩擦系数建议取0.3.

The penetration of composite bucket foundation is a vital construction process.The soil is disturbed undernegative pressure in the process,and both soil pressure and pore water pressure in soil are changed,which affectspenetration resistance.A large-scaled model test on the penetration process of composite bucket foundation was carriedout in silty clay.During the test,the pressure in compartments,soil pressure and pore water pressure in surroundingsoils were monitored.Moreover,the required negative pressure for penetrating was predicated throughtheoretical calculation,and the negative pressure applied to the test was compared with the predicted negative pressure.The results show that the soil pressure and pore water pressure in the soil around the foundation are bothreduced.In addition,the inner soil pressure near the skirt decreases more than the outer soil pressure.When thefoundation starts to tilt,the feasibility of bucket tilt adjusting technique is validated by applying suction to highercompartments.The predicted negative pressure is larger than the applied negative pressure in the test.When Houlsby’smethod is adopted to calculate the penetration resistance of a bucket foundation in silty clay,the friction coefficient isrecommended to be0.3.