长江上游德感坝采砂坑对河床演变影响分析

The analysis of the influence of the degan gravel pits on riverbed development

在长江上游德感坝副槽采取格形开挖方式,共挖掘了4个采砂坑.文章通过分析长江德感坝河段的河床演变,建立和验证平面二维水流数学模型,选取四级代表流量计算几江河段采砂前后的流场变化,观察一个水文年后的河势,认为采砂河段的河势无大的变化,采砂坑很难造成溯源冲刷,对涉河建筑物的稳定性影响甚微;但是在洪水期,采砂坑周围较短范围内发生局部的垮塌,相邻采砂坑之间的采砂埂不易稳定,需加强过江管道上采砂埂的保护性措施.

Four gravel pits were excavated along the secondary channel by way of grid-type excavation at Degan shallow patch in upper Changjiang river.After founded and validated the two dimensional mathematical model, the changes of the flow field with four representative flow quantities was calculated.The riverbed development of Degan river section was analyzed and the river regime of one hydrographic year was observed.Thus the conclusion could be reached that few changes would take place to river regime and backward erosion would hardly happen because of these gravel pits.The influence to wading constructs is very little.Partial collapse happens in a short range around gravel pits in flood.The sand peduncle above pipeline between two gravel pits isn't steady enough,so conservation measure is necessary.