Study On The Hydrodynamic Characteristics Of Double-layer Arc Plate Type Permeable Embankment

The plate type permeable embankment is a scientific research innovation in recent years.Its advantages over traditional dykes are:(1)It is beneficial to the exchange of water before and after the breakwater,which is conducive to protecting the local ecological environment from large-scale damage;(2)Applicable In the deep sea area;(3)the project cost is lower,less consumables;(4)the structure is relatively simple and easy to construct.Following the recent policy on the creation of marine pastures,there is an urgent need to create a new type of breakwater.The construction of the through-type breakwater can play an important role in the protection of marine pastures in the offshore area.The development of the plate-type permeable embankment will lead to the transformation of the marine breakwater and has broad development prospects.Researchers have pointed out that the circular plate structure has better stress characteristics than the flat plate,and the lower arc plate has better wave-eliminating effect.This is mainly because there are certain differences in the wave-eliminating principle of different structures.The flat-type air permeable levee mainly breaks the vertical trajectory of the water quality point,so that the wave has a shallow water effect and then breaks the energy and reduces the transmission wave height.The wave-facing area of the lower arc-plate type permeable embankment is larger than that of the flat-type permeable embankment,and the wave needs to climb along the embankment surface,and its effect on the wave is more obvious;the shape of the plate determines the longitudinal and lateral movement of the water quality point.Will be disturbed,the shallow water effect is significant,and the fragmentation phenomenon is severe.Compared with the lower arc plate type permeable embankment,the upper arc plate type permeable embankment has no energy dissipation effect during the climbing process,and the transmission and reflection are larger than the lower arc plate type permeable embankment.This paper is based on the previous research on the plate type permeable embankment and then an in-depth exploration of the double-layer arc plate type permeable embankment.The double-layer arc-plate type permeable embankment is mainly composed of two curved plates and a new wave-eliminating structure.In order to study the hydrodynamic characteristics of the double-layer arc-plate type permeable embankment,this paper tests the depth of the permeable embankment by placing different types of permeable dikes into the test tank,the spacing between the two plates,the height of the double-layer arc plates,etc.Waveout performance and the effects of stress.The hydrodynamic characteristics of the penetrating levee are analyzed from various factors such as reflection coefficient,transmission coefficient,wave energy and pressure,in order to obtain a transparent levee form with good wave eliminator.The following research results were obtained:(1)The reflection coefficient of the double-arc transparent tank with an arc height of0.10 m is small due to the relative plate width,wave height,period,plate spacing and potential depth,but the numerical value is smaller than the 0.05 m arc height.K_r both are less than 0.2.(2)As the wave height increases,the transmission coefficient of the air permeable bank increases.For a 0.05 m arc height permeable bank,the transmission coefficient is less affected by the variation of the plate spacing.For an open-air embankment with an arc height of 0.10m,it can be generally found that the transmission coefficient of the plate is small when the arc height is close to the spacing between the plates.The change of latent depth has a great influence on the wave-breaking of the permeable embankment.The transmission coefficient of the submerged embankment(h=0.03m)is relatively poor,and the transmission coefficient of the water dike(h=-0.03m)is smaller.The change of the latent depth has a great influence on the wave-eliminating effect of the air-permeable embankment.The transmission coefficient of the air-permeable embankment is relatively poor in the water-discharging state,and the wave-breaking state is better in the water-discharging state.(3)For an open-air embankment with an arc height of 0.05m,the transmission coefficient of the permeable embankment decreases as the W/L increases.For an open-air embankment with an arc height of 0.10 m,the transmission coefficient of the transparent embankment increases first and then decreases with the increase of W/L.(4)The point pressure and the increase of the total pressure with time t show periodic changes.The positive pressure and negative pressure of the upper and lower surfaces of each plate of the permeable bank are mostly symmetrical about the horizontal axis.(5)The total vertical wave force is much larger than the horizontal wave total force,indicating that the air levee is mainly longitudinal wave-eliminating,but the positive and negative forces are similar.The horizontal vertical wave total force of the transparent levee with an arc height of 0.10 m is greater than the permeable embankment with an arc height of0.05 m.(6)The total wave force tends to decrease with the increase of the relative plate width,and the change of the double arc plate type permeable embankment with 0.05m arc height is small.The wave force of the wave for the submersible levee(h=0.03m)is less than the wave force of the wave for the submersible breakwater(h=0m)and the submersible levee(h=-0.03m).