波浪周期对防波堤护面块体稳定性影响的试验分析     

柳玉良  王海峰  卢燕 《海岸工程》2012,(3):9-14

波浪对斜坡堤护面结构的冲刷破坏作用受诸多因素的影响,如波浪要素、水深条件、坡面角度、护面块体型式等。在进行某项有关斜坡堤护面块体的课题研究中发现,当防波堤断面结构确定后,护面人工块体的稳定性主要取决于波高及波周期的变化。在进行这方面内容设计计算中,通常波高的取值都能给予足够的重视,但波周期对护面块体稳定性的影响容易被忽视。本研究通过物理模型试验,针对波浪周期对斜坡堤护面块体稳定性的影响进行了总结分析,为防波堤设计提供参考。  相似文献   

Experimental study of pore water pressure and bed profile change under regular breaking waves   总被引：1，自引：0，他引：1  

程永舟  蒋昌波  赵利平  潘昀  李青峰 《中国海洋工程》2012,26(3):457-468

  相似文献   

天津滨海高新区综合服务中心坡屋顶绿化设计与施工     

祁永  李湧  祝吉峰 《中国勘察设计》2009,(12):80-81

天津滨海高新区综合服务中心坡屋面绿化项目总面积约9600m2,坡度为11.5度。该项目在设计施工过程中,采用新型无机种植基质材料、配以防滑坡新做法,以及坡屋面排水技术措施改革方面都取得了非常好的收效,使建筑绿化系统集成技术又积累了宝贵的经验。  相似文献   

北方土石山区坡耕地水土保持措施的 空间有效配置   总被引：8，自引：0，他引：8  

和继军  蔡强国  王学强 《地理研究》2010,29(6):1017-1026

坡耕地是北方土石山区水土流失的重要策源地,为了有效防治坡耕地水土流失,提高坡耕地持续利用,分析了不同水土保持措施在坡耕地上的适用范围,研究结果显示,耕作措施的水土保持效益随着坡度的增加而降低,在0°~6°的坡度范围内水土保持效果最佳;坡改梯工程的适用范围广泛,水土保持效益稳定,但在陡坡上实施坡改梯工程的难度和成本将显著增加,维护费用高,且土地的损失量大,不宜在土地资源紧张的贫困山区大面积推广;植物篱措施的水土保持效益受坡度的限制性小,在25°以下的坡地上都能收到良好的水土保持效果,且投资少,适合在在广大贫困山区使用。因此,根据北方土石山区的坡耕地的特点及不同水土保持措施最佳适用范围,坡耕地被划分为4个坡度范围分别进行水土保持措施的优化配置,即0°~5°平地及浅丘地采取以耕作措施为主进行治理,5°~15°缓中坡耕地采用以梯田措施为主、植物篱措施为辅进行治理,15°~25°的坡耕地采用植物篱措施为主进行治理,25°以上坡耕地必须退耕还林还草。  相似文献   

Lumped surface and sub‐surface runoff for erosion modeling within a small hilly watershed in northern Vietnam          下载免费PDF全文

Yen Tan Bui  D. Orange  S. M. Visser  Chu Thai Hoanh  M. Laissus  A. Poortinga  Duc Toan Tran  L. Stroosnijder 《水文研究》2014,28(6):2961-2974

Developing models to predict on‐site soil erosion and off‐site sediment transport at the agricultural watershed scale represent an on‐going challenge in research today. This study attempts to simulate the daily discharge and sediment loss using a distributed model that combines surface and sub‐surface runoffs in a small hilly watershed (< 1 km²). The semi‐quantitative model, Predict and Localize Erosion and Runoff (PLER), integrates the Manning–Strickler equation to simulate runoff and the Griffith University Erosion System Template equation to simulate soil detachment, sediment storage and soil loss based on a map resolution of 30 m × 30 m and over a daily time interval. By using a basic input data set and only two calibration coefficients based, respectively, on water velocity and soil detachment, the PLER model is easily applicable to different agricultural scenarios. The results indicate appropriate model performance and a high correlation between measured and predicted data with both Nash–Sutcliffe efficiency (Ef) and correlation coefficient (r²) having values > 0.9. With the simple input data needs, PLER model is a useful tool for daily runoff and soil erosion modeling in small hilly watersheds in humid tropical areas. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

The use of grain size trend analysis in macrotidal areas with breakwaters: Implications of settling velocity and spatial sampling density   总被引：1，自引：0，他引：1  

T.A. Plomaritis  D. Paphitis  M. Collins   《Marine Geology》2008,253(3-4):132-148

In a macrotidal environment with offshore breakwaters (Elmer, West Sussex) a new approach for the identification of the sediment transport pathways with grain size trend analysis (GSTA) was undertaken using statistical parameters (mean, sorting and skewness) directly derived from settling velocities distributions. The same samples were analysed with sieving (quarter- and half-phi resolution) and GSTA was performed again in order to directly compare the resultant sediment transport directions derived with the two analytical techniques. Furthermore, both regular and irregular sampling distributions were used to recalculate GSTA. Hydrodynamic data were collected in different locations around the breakwaters and net sediment transport directions were calculated in order to assess the accuracy of the sediment transport pathway directions derived with the different analytical techniques.The accuracy of settling velocity in determining the statistical parameters of the grain size distribution is identified, especially for the fine-medium sand sediments. Settling velocities produced better results than the sieving; the quarter-phi resolution producing the poorer results in comparison with the coarser half-phi resolution. The results for the different spatial sampling strategies are found to depend upon the number of samples utilised; that shows that the accuracy of the GSTA is based upon the ability of representing, adequately, the spatial distribution of the sediment parameters.  相似文献   

滇东北山区坡耕地水土流失状况及其危害   总被引：7，自引：1，他引：6  

杨子生 《山地学报》1999,(Z1)

应用新近建立的滇东北山区坡耕地土壤流失方程测算了该区域坡耕地年均土壤流失量,探讨了水土流失的严重性和基本特征,分析了水土流失对耕地适宜性与可持续性的影响和破坏  相似文献   

The interaction of surface water waves with submerged breakwaters   总被引：1，自引：0，他引：1  

M. Christou  C. Swan  O.T. Gudmestad 《Coastal Engineering》2008,55(12):945-958

This paper concerns the behaviour of nonlinear regular waves interacting with rectangular submerged breakwaters. A new series of experimental results is presented and compared with numerical calculations based upon a Boundary Element Method (BEM) that utilises multiple fluxes to deal with the discontinuities encountered at the corners of the domain. Specifically, comparisons concern both the spatial water surface profiles at various times and the spatial evolution of the harmonics generated by the breakwaters, the latter being an important focus for the paper. The BEM is shown to accurately model both the water surface profile and the harmonic generation, provided the breakwater width is sufficient to ensure that flow separation is not a controlling influence. Furthermore, evidence is provided to confirm that reflection from rectangular submerged breakwaters is fundamentally a linear phenomenon.  相似文献   

On a new wave energy absorber     

Paolo Boccotti 《Ocean Engineering》2003,30(9):1191-1200

It is a commonly held opinion that only a forced resonance is possible between random wind-generated waves and wave energy absorbers; the forced resonance being pursued by means of devices for phase control. We show, instead, that it is possible to obtain an impressive natural resonance between random wind-generated waves and a new kind of absorber beneath the sea level. The proof is given through a small scale field experiment. This finding should enable us to defend coasts with a very low environmental impact and to use breakwaters for converting large quantities of wave energy into electric power.  相似文献   

Hydrodynamic studies on vertical seawall defenced by low-crested breakwater     

M.G. Muni Reddy  S. Neelamani   《Ocean Engineering》2005,32(5-6):747-764

This paper presents results obtained from a series of experiments conducted in wave flume to assess the influence of the offshore low-crested breakwater as a defence structure in reducing the wave forces on vertical seawall. The main aim of the tests was to know the effect of crest elevation of the offshore low-crested breakwater as a rehabilitation structure for the existing damaged shore protection structures. In this study five relative breakwater heights are used and associated flow evolution was analyzed. With the sections proposed in this study, it is possible to achieve considerable reduction of wave force on the seawall. Modification factor is proposed to estimate the shoreward force on the seawall defenced by low-crested breakwater.  相似文献