南海西部某风电场海底沙波特征演化及冲刷防护

    Sandwave characteristic,evolution and erosion protection of wind farm in the western South China Sea

    • 摘要: 海底沙波的发育对海上风电场设计、安装和后期运维有诸多不利影响。结合南海某风电场区多次勘察结果,分析了场区内海底沙波沙脊的发育特征、运移规律及其控制机制。结果表明:研究区内沙波的发育存在空间差异,直线形沙波通常发育在沙脊顶部和尾部,新月形沙波和弯曲形沙波发育在沙脊槽内的平坦地形上,分叉形沙波为直线形沙波的前身。北部沙波整体向南迁移,南部沙波整体向北部移动,转换带为两侧沉积物汇集区,处于长期稳定状态。研究区沙波发育主要经历新月形沙波、弯曲形沙波—分叉形沙波—直线形沙波3个演化阶段;随着沙波的演化,沙波的规模逐渐增大,移动性逐渐减弱。针对风机桩基冲刷防护,可采用在桩基周围增加仿生水草垫或水工布等方式,增加海床稳定性,减小桩基周围的冲刷。

       

      Abstract: The development of seabed sand waves has many adverse effects on the installation, construction, and subsequent operation and maintenance of offshore wind farms. Based on the survey results of a wind farm in the South China Sea, we analyzed the developmental characteristics, migration pattern, and control mechanism of seabed sand ridge in the field. Results show that there are spatial differences in the development of linear sand waves in the study area. Linear sand waves usually develop on the top and tail of the sand ridge; crescent sand waves and curved sand waves develop on the flat terrain in the sand ridge trough; and forked sand waves are the predecessor of linear sand waves. The sand waves in the north migrated southward as a whole due to falling tidal flow, while the sand waves in the southern part of the study area migrated northward as a whole due to rising tidal flow, and the transition zone was the area where sediments converged on both sides, reflecting a long-term stable state. The development of sand waves in the study area experienced three evolutionary stages, namely, crescent or curved sand waves, bifurcated sand waves, and linear sand waves. With the evolution of sand waves, the scale of sand waves gradually increased and the mobility gradually weakened. To protect wind turbine pile base from scouring, bionic water grass mats, rocks, or hydraulic fabrics can be applied around the pile foundation to increase the stability of the seabed and reduce the scour around the pile base.

       

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