波浪荷载下振动管道周围粉质海床的孔压响应和冲刷室内水槽研究

Study on response of water pressure in pore and erosion of silty seabed around vibrating submarine pipes under wave loads based on laboratory flume experiment

使用直径为28和46 mm的模型钢管、偏心轮起振器、测波仪、孔隙水压力传感器和超声地形测量仪等,通过比尺为1∶12和1∶20室内波流水槽试验,运用控制变量对比实验法,分析波浪荷载下振动管道周围粉质海床的孔隙水压力响应和冲淤情况。结果表明管道振动和波浪荷载都会导致土体液化,但前者作用远大于后者;波高增加会导致管道周围土体孔隙水压力的最大值增大,而水深增加会导致孔隙水压力的累积程度变大,发生液化需要的时间增长;波浪作用下,海床表面呈均匀下降趋势,海床表面出现波痕,管道正下方被掏蚀;振动管道两侧出现平行于管道的凹槽,直到管道两侧的土体被冲蚀,与管道下方的掏空连成一片,最终形成冲刷坑,管道产生悬跨。

The controlled variable comparison method was used to analyze the response of water pressure in the pore and erosion of silty seabed around the vibrating pipeline under wave loads based on the laboratory flume experiment.The scale was 1∶12 and 1∶20.The model steel pipes with diameters of 28 mm and 46 mm,eccentric vibrators,wave meters,pore water pressure sensors and ultrasonic topographic measuring instruments were used.The results show that pipeline vibration and wave load can both cause the soil liquefaction,but the effect of pipeline vibration is much bigger than that of the wave load.The maximum value of the water pressure in the pore on the soil around the pipeline increases with the wave height.The increase of water depth will also cause the accumulation of water pressure in the pore to increase,and the time required for liquefaction will increase accordingly.Under the wave load,the surface of the seabed shows a uniform downward trend.Wave marks occur on the surface of the seabed,and the pipeline is etched directly underneath.There are grooves parallel to the pipeline on both sides of the vibrating pipeline,until the soil on both sides of the pipeline is eroded and connected to the hollow under the pipeline,finally an erosion pit is formed,and the pipeline has an overhang.