Experimental Study On Reasonable Distance Of Permeable Gabion Groin

On account of low cost, fast construction, obtaining local materials, environmental protection ofzoology, gabion groin is widely used in domestic and international river regulation projects. But for lack ofdesign information and theoretical analysis of the gabion groin in the actual project, relevant information isnot directly applicable, can only be a reference entity groins and a direct result is the design work isdifficult, even severely damaged. Designers are often only based on their own experiences and the project’stechnical, safety and economy are the big test. How much spacing has been used is one of the problems beconcerned of the project, that is closely related about the effect of this engineering and engineeringeconomics. If the spacing is too large, the effect of remediation project will be greatly reduced can not evenreach the project purpose; if the spacing is too small will resulting in waste. In past studies, mostly based onlaboratory data to derive the principles of spacing resulting layout and mostly too large when it used inpractical application to the project; while1-4times spacing which is selected based on engineeringexperience is safe and reliable, but there is little relevant theoretical and experimental validation cansupport it. This article from the both of experimental and numerical to analysis structural features and watererosion law when the pitch is1-4times of the permeable spur dikes in the practical application ofengineering selected to arrive at a reasonable distance between groins to guide engineering.In this paper, gabion groin for bank revetment which was applied to Manasi river in Xinjiang duringthe process of river regulation is investigated, found that the presence problems about the security andeconomy of operation then propose appropriate solutions. Further by the mathematical modeling andindoor generalized flume test to analytical investigation many key issues such as flow structure and erosionlaws near the in a different space.First, through the fixed bed model test, to carefully measure the water flow velocity field and freesurface in the sink by rotary pulp flow meter and homemade needle，then carefully analyse the flow patternat different space near the spur dikes. Found that the flow regime had larger changes under the differentspacing in the dam plot. In this paper, this situation had be detailed analysis through physical experimentsand verified each other with the mathematical simulation dynamic demonstration results.Then, the variation of flow structure near groins under different parameters is observed by rotary pulpflow meter and homemade needle. The research indicate that with increasing of dam length, resistanceeffect, narrowed effect and deflecting effect become strengthened, in the upstream water surface close tothe side of groins become more obvious, and the larger range of flow surface descend, the slower mainstream recovered. Compared with the orthogonal groins, with the decrease of bucket angle, the resistanceeffect of groins slow down and the effect of sending slip become strengthened. In the upstream watersurface close to the side of groins decrease, range of flow surface descent increases slowly, streamlinebecome smooth, meanwhile, using theoretical analysis to deduce the computational formula about thesurface curve and partical head loss.After that, to observe the erosion process and analyze scour mechanism through water erosionexperiment, and using Surfer software to draw riverbed morphology diagram after scouring, obtainedvariation erosion near groyne of different setup parameters. Comparative analysis of local scour effectsbetween the single spur dike and dam group found that: After setting the dam base, lateral notching groinsand vertical notching near the first groyne are similar to the single erosion, but scour case of the second andthird were large difference from the first, the scour of the second groin is the smallest, the third seat is farless than the first, but slightly larger than the second groin. By using the method of dimensional analysis todeduce respective burial depth in different spacing about dam group with three spur dikes. Next, using surfer software, calculating spur dikes sediment quantity of scour-silt about the mainchannel area and dam district under different spacing circumstances, found that with increasing length ofthe dam, the amount of erosion and siltation have increased, but the amount is always less than the erosionsedimentation volume. Compared with orthogonal groin, when other conditions remain unchanged, withbucket angle decreasing, scouring and siltation volumes tended to decline and the decreased tendency ofscouring volumes is more than that siltation volumes.Finally, according to the flow structure and the law of the scour which analysed previously, based onthe principles: reducing flood hazards, the main channel not silted, dam fields not dam, safety and stabilitydam and economic etc. to determine a reasonable distance between spur dikes and explore dam burieddepth of each group.