A Study On Feasibility Of Common Methods In Breast Wave Force Estimation Of Deep Water Combined Breakwater

Breakwater is an important hydraulic structure in coastal engineering, and alongwith deep-water port construction, breakwater construction water is increasing.China’s newly enacted Breakwater Design Specification (JTS154-2011) explicitlystates that those breakwaters with a water level of more than20m are known asdeep-water breakwaters, and emphasizes that the design principles, methods andconstruction requirements are different from those of the common shallow waterbreakwaters. However, the specification does not specify how to choose the waveforce calculation methods of deep-water breakwater. Traditional types of breakwatersare sloping, vertical and mixed types. The mixed type, which has the advantages ofreduced engineering, lower cost and upper caisson stability, is widely used indeep-water breakwater construction.In order to study the Sainflou formula, Goda wave pressure formula, themodified version of Goda wave pressure formula in Japan Harbor TechnologyResearch Institute, and the applicability of vertical breakwater wave force calculationformula in Harbor Hydrological Norms(JTJ213-98) into the estimation of deep-watermixed breakwater wave force, using the above methods, this paper estimates fourkinds of water depth of mixed-type deep-water breakwater with intermediate and highbedding and wave forces with three kinds of wave height, then presents the pressuredistribution of vertical wave force, total horizontal force, bottom buoyancy force, andcompares the differences of the above four analysis methods. Based on the physicalmodel tests in Qingdao Navy Engineering Design and Research Institute, which,using the elements of water depth and wave height, simulate the above estimation ofmixed-type breakwater with intermediate and high bedding under the affection ofwave, this paper measured and recorded the horizontal wave pressure, bottom verticalwave pressure and wave height. It further analyzes the probability horizontal pressuredistribution of mixed-type deepwater breakwater under the function of wave, pressure distribution, and the diachronic change rule of wave pressure, and by comparing theexperimental results with the estimated results using the above four calculationmethods, it studies the applicability of the various methods into the calculation ofmixed-type deep-water breakwater wave force.Through the physical model data analysis and comparison of the estimationresults, this paper arrives at the following conclusion:1. The incident wave force distribution on the vertical wall, which is under thedirect impact of wave, is non-uniform. The place lower than the static water level isthe main impact area with large wave force and with the change of height, there is nosignificant change in wave force strength. In the area where wave force reduces, thestrength of wave force decreases rapidly as height increases.2. The depth of vertical wall water increases as that of the breakwater water rises,which increases the energy and height of wave. As a result, with the depth of waterlevel rising, the total horizontal wave force on the vertical wall increases.3. The peak of floating force and the peak of total horizontal wave force do notappear at the same time. Under the standing wave force state, the peak of floatingforce appears after the peak of total horizontal wave force, and under the breakingwave force state, the peak of floating force appears almost the same time with thesecond peak level total horizontal wave force; under the standing wave force state, thepeak of floating force first increases and then decreases with water depth increasing,and under the breaking wave force state, it decreases with water depth increasing.4. In the estimation of the wave force of mixed-type deepwater breakwatercaisson with intermediate bedding, Goda pressure formula applies to the case of thewater depth less than42m; the specified method in China is suitable for standingwave situation.5. In the estimation of the wave force of mixed-type deepwater breakwatercaisson with high bedding, Goda pressure formula applies to the case of the waterdepth more than33m; the specified method in China is suitable for stand wavesituation.6. In the estimation of the floating wave force of mixed-type breakwater deepwater vertical wall, Goda pressure formula applies to the case in which theintermediate bedding and wave height are more than7.0m, and except the above cases,the estimation results are larger than the measured results.