波流作用下单桩基础局部冲刷试验研究

Experimental study on local scour of monopile foundation under combined action of waves and currents

深水基础在服役期间受到长期的波流联合作用,桩周局部冲刷问题是工程界关注的主要问题。通过对不同桩径单桩基础开展的波浪和水流联合作用的模型水槽试验,得到不同水力条件下的桩周局部冲刷深度发展的时程曲线以及最终形成的冲刷坑状态。发现波流联合作用下的冲刷深度发展相较于单独水流作用更加剧烈,小直径桩相比于大直径桩具有更快的冲刷速率,提出了基于Fra的冲刷深度预测公式,并指出预测公式运用于工程实际中时需乘以安全系数1.2,以确保得到的冲刷深度预测是安全可靠的。

A deep-water foundation is subjected to the combined action of waves and currents for a long time during its service, and the local scour around a pile is the main problem concerned by the engineering community. Through the flume test of the combined action of waves and currents on monopile foundations with different pile diameters, the time history curve of the development of local scour depth around the pile under different hydraulic conditions and a picture of the final scour hole are obtained. It is found that the development of scour depth under the combined action of waves and currents is more intense than that of the action of single currents, and a small-diameter pile has faster scour rate than a large-diameter pile. The prediction formula of scour depth based on Frais proposed, and it is pointed out that the prediction formula needs to be multiplied by safety factor 1.2 when applied to engineering practice, so as to ensure that the prediction of scour depth is safe and reliable.