不规则波浪作用下植物蜂巢生态护岸水动力特性试验研究

Experimental Study on Hydrodynamic Characteristics of Vegetated Ecological Honeycomb Revetment Under Irregular Waves

摘要

综合考量自然环境与岸坡防护需求,植物生态护岸结构的水力特性研究对生态护岸的发展、岸坡的治理及保护具有重要意义．为探究不规则波浪作用下柔性植被与蜂巢格室结合的复合型护岸系统的水动力特性,以天津沿海典型碱蓬植被-蜂巢护岸体系为研究对象,开展不规则波浪作用下水槽模型试验,探讨植物密度和高度对蜂巢生态护岸断面不规则波浪爬高、越浪及波生流近底流速的影响．研究发现随着植物密度和高度的增加,不规则波浪的爬高和越浪均呈现下降趋势,各波浪要素作用下的不规则波浪爬高衰减率在10%～50%之间,越浪衰减率最大达到90%以上．设计高水位时,较小的植物高度反而会使近底流速略微增大,较大的植物高度才能起到降低近底流速、减小对坡面冲刷影响的效果．与规则波浪作用下试验结果相比,不规则波浪的波浪爬高衰减率最大降低至40%,越浪衰减率最大可达到90%以上．研究结果表明植物对不规则波浪的波高衰减效果更好,对越浪衰减程度两者均较好．因此,植物蜂巢生态护岸在规则波浪与不规则波浪作用下均能起到有效削弱来浪的效果,通过增加种植植物的高度及密度能更有效地防护岸坡．探究不规则波浪作用下柔性植被的密度与高度对蜂巢生态护岸水动力特性的影响规律,能够为相关生态护岸工程的设计与施工提供参考．

Abstract

With the comprehensive consideration of natural environment and the requirements for bank slope protection, the research on the hydrodynamic characteristics of vegetated ecological revetments is crucial for the development of ecological revetments, as well as the management and protection of bank slopes. To study the hydrodynamic characteristics of a composite revetment system combining flexible vegetation and honeycomb structures under irregular waves, a revetment system consisting of Suaeda salsa which is typical in the coastal area of Tianjin and honeycomb structures is taken as a research object in this paper, and water-tank model experiments were conducted under irregular waves, so as to examine the effects of plant density and plant height on the irregular wave run-up, overtopping and near-bed flow velocity. Results demonstrate that both the wave run-up and the overtopping of irregular waves decreased with the increasing plant density and plant height. The attenuation rates of irregular wave run-up ranged from 10% to 50% across the tested conditions, while the maximum attenuation rate of overtopping exceeded 90%. At the design high-water level, a smaller plant height was found to slightly increase the near-bed flow velocity, whereas a greater plant height can effectively reduce the velocity, thereby mitigating the impact of potential slope scour. Compared with the experimental results under regular waves, the attenuation rate of irregular wave run-up was as low as 40%, while the attenuation rate of overtopping can reach over 90%. These findings confirm that the plants are more effective for the attenuation of irregular wave run-up, but they are conducive to the attenuation of overtopping under both the regular and irregular waves. Therefore, the vegetated ecological honeycomb revetment can effectively dissipate the incoming wave energy under both waves, and its protective performance can be enhanced by increasing the plant density and height. The exploration of the effects of the density and height of flexible vegetation on the hydrodynamic characteristics of ecological honeycomb revetments can provide a reference for the design and construction of similar ecological revetment engineering.

关键词

不规则波浪 / 植物蜂巢生态护岸 / 越浪 / 爬高 / 水槽模型试验

Key words

irregular wave / vegetated ecological honeycomb revetment / overtopping / run-up / water-tank model experiment

参考文献

[1] Coelho C, Cruz T, Roebeling P. Longitudinal revetments to mitigate overtopping and flooding: Effectiveness, costs and benefits[J]. Ocean & Coastal Management, 2016, 134: 93-102.

[2] Day J W, Boesch D F, Clairain E J, et al. Restoration of the Mississippi Delta: Lessons from hurricanes Katrina and Rita[J]. Science, 2007, 315(5819): 1679-1684.

[3] 李梦琦. 规则波与同向水流环境中柔性植被消浪数值模拟[D]. 南京: 东南大学交通学院, 2022.

[4] Li Mengqi. Simulation Study on Wave Attenuation Through Flexible Vegetation with Following Currents[D]. Nanjing: School of Transportation, Southeast University, 2022(in Chinese).

[5] Quartel S, Kroon A, Augustinus P G E F, et al. Wave attenuation in coastal mangroves in the Red River Delta, Vietnam[J]. Journal of Asian Earth Sciences, 2007, 29(4): 576-584.

[6] Tran Q B. Effect of mangrove forest structures on wave attenuation in coastal Vietnam[J]. Oceanologia, 2011, 53(3): 807-818.

[7] Nguyen B T, Nandasena N A K, Dang V H, et al. Effect of river vegetation with timber piling on ship wave attenuation: Investigation by field survey and numerical modeling[J]. Ocean Engineering, 2017, 129: 37-45.

[8] Henderson S M, Norris B K, Mullarney J C, et al. Wave—frequency flows within a near—bed vegetation canopy[J]. Continental Shelf Research, 2017, 147: 91-101.

[9] 杨沛钧. 柔性植被作用下波浪沿斜坡爬升过程的数值模拟[D]. 天津: 天津大学建筑工程学院, 2020.

[10] Yang Peijun. Numerical Simulation of Flexible Plant Effects on Wave Propagation Along the Slope[D]. Tianjin: School of Civil Engineering, Tianjin University, 2020(in Chinese).

[11] 曹大正, 王银生, 张冬然, 等. 互花米草在吹填筑挡工程上的试验与应用[J]. 中国工程科学, 2005, 7(7): 14-23.

[12] Cao Dazheng, Wang Yinsheng, Zhang Dongran, et al. Application of Spartina alterniflora on blow—fill—construct sea wall engineering[J]. Engineering Science, 2005, 7(7): 14-23(in Chinese).

[13] Yang S L, Shi B W, Bouma T J, et al. Wave attenuation at a salt marsh margin: A case study of an exposed coast on the Yangtze Estuary[J]. Estuaries and Coasts, 2012, 35(1): 169-182.

[14] Hashim A M, Khairuddin N. Performance of mangrove forests in coastal protection[J]. Applied Mechanics and Materials, 2014, 567: 277-282.

[15] Mazda Y, Magi M, Kogo M, et al. Mangroves as a coastal protection from waves in the Tong King delta, Vietnam[J]. Mangroves and Salt Marshes, 1997, 1(2): 127-135.

[16] Yin Z G, Yang X Y, Liang B C, et al. Experimental investigation of wave attenuation through flexible plants on a flat bed[J]. Journal of Coastal Research, 2018, 34(3): 718-723.

[17] 白玉川, 杨建民, 胡嵋, 等. 植物消浪护岸模型实验研究[J]. 海洋工程, 2005, 23(3): 65-69.

[18] Bai Yuchuan, Yang Jianmin, Hu Mei, et al. Model test of vegetation on the bank to attenuate waves and protect embankments[J]. The Ocean Engineering, 2005, 23(3): 65-69(in Chinese).

[19] 王一航. 规则波作用下植物蜂巢生态护岸水动力特性研究[D]. 天津: 天津大学建筑工程学院, 2019.

[20] Wang Yihang. Study on Hydrodynamics of Ecologically Vegetated Honeycomb—type Revetment Under Regular Waves[D]. Tianjin: School of Civil Engineering, Tianjin University, 2019(in Chinese).

[21] Tschirky P, Hall K, Turcke D. Wave attenuation by emergent wetland vegetation[C]//27th International Conference on Coastal Engineering(ICCE). Sydney, Australia, 2000.

[22] Lara J L, Maza M, Ondiviela B, et al. Large—scale 3—D experiments of wave and current interaction with real vegetation. Part 1: Guidelines for physical modeling[J]. Coastal Engineering, 2016, 107: 70-83.

[23] Zhang J F, Zhang N, Zhang Q H, et al. Numerical simulation of wave overtopping of an ecologically honeycomb—type revetment with rigid vegetation[J]. Journal of Marine Science and Engineering, 2022, 10(11): 1615.

[24] 吴迪, 冯卫兵, 石麒琳. 柔性植物消浪及沿程阻流特性试验研究[J]. 人民黄河, 2014, 36(12): 79—81, 84.

[25] Wu Di, Feng Weibing, Shi Qilin. A physical model study of the effect of the flexible vegetation on wave height attenuation and along the way of flow structure[J]. Yellow River, 2014, 36(12): 79-81, 84(in Chinese).

[26] 张娜, 张金凤, 张庆河, 等. 规则波作用下柔性植物蜂巢护岸水动力特性试验研究[J]. 天津大学学报(自然科学与工程技术版), 2021, 54(5): 441-449.

[27] Zhang Na, Zhang Jinfeng, Zhang Qinghe, et al. Experimental study of the hydrodynamics of revetment protection using honeycomb—type, flexible plants under the action of regular waves[J]. Journal of Tianjin University(Science and Technology), 2021, 54(5): 441-449(in Chinese).

基金资助

天津市科技计划资助项目(2019-1)

天津市交通运输科技发展计划资助项目(2020-12)