管袋坝袋间接缝侧壁损漏冲刷模型试验

Experimental study on scouring along seams between tubes of a punctured geotube dam

针对管袋内充填砂从管袋侧壁缺损处外漏流失问题,采用自行研制的管袋坝袋间接缝侧壁损漏冲刷稳定性试验研究装置,进行了单向流和波浪作用下管袋坝袋间接缝侧壁损漏冲刷试验,总结了冲刷过程及接缝管路内砂颗粒的运移规律,并分析了单向流工况下破损口大小对冲刷稳定性的影响。结果表明:单向流工况管袋坝袋间接缝侧壁损漏冲刷稳定性与最粗砂颗粒的起动流速、接缝内水流流速及破损口大小有关,破损口越大、水流流速越大、最粗砂颗粒起动流速越小,越容易发生冲刷破坏;波浪工况下,选择临界峰值水压力作为管袋坝袋间接缝侧壁损漏冲刷稳定性的判定指标,通过比较实际工程中管袋坝接缝所受峰值水压力与临界峰值水压力可以判断波浪工况下的冲刷稳定性。

For the problem of sand erosion from the side walls of punctured geotubes,a set of experimental apparatus was developed to study the erosion stability along seams betw-een tubes of a punctured geotube dam. Based on the experiments in both unidirectional flow and wave flow conditions, characteristics of erosion process and sand transport in the seams between geotubes were summarized. The impact of breakage on the scouring stability in unidirectional flow conditions was also analyzed. The results show that scouring stability in the seams between geotubes in unidirectional flow conditions is related to the threshold velocity of the sand particles with the maximum diameter, velocity magnitudes inside the seam and the extent of the breakage. Scouring instability can easily occur in the case of larger breakage, higher flow velocity and lower threshold velocity of sand particles. In wave flow conditions, the critical peak water pressure is selected as a criterion parameter to determine the stability of seams between punctured geotubes. The scouring stability in wave flow conditions for real engineering works can be determined by comparing the peak water pressure in the seams with the critical value.