Fence Board

As the name implies, the fence slab is a concrete plate with holes. It is a new artificial block successfully put forward by Professor Hou Guoben of Shandong Ocean University and the colleagues of the Marine Engineering Dynamics Research Group. Fence board is a kind of concrete hole plate, it is evolved on the basis of concrete plate. Fence slab uses its own stable weight and the mutual interlocking effect between the blocks, so that the slope has a certain integrity, the space within the block body is for wave dissipation.

Application Design

1. Determination of the size

As the protection layer of the slope dike, the size of the fence slab should consider two requirements: One is the stability of the fence board itself, stability is mainly controlled by three factors, which is, whether the block sliding, rolling and lifting out; the second is the robustness, the fence board laid in the protective surface, under the action of the wave, the wave of the attack force, the board of water support, the hydrostatic pressure between plate and plate, and the weight of the plate and the friction between the plate and the slope, the wind force, etc..

2. hole type and size determination

The type and size of the hole are determined by the effect of wave elimination. However, for the convenience of construction, the grid type is mostly used at present. There are two kinds of grids, single row and double row. And the hole grid can be divided into upper and lower through and not through. Through is better. Most of the holes are designed as rectangles, but they must meet the requirements of cushion size, that is, to ensure that the cushion under the plate is not pulled out by waves as the criterion. The spacing of holes should be determined according to the strength requirements of the block. At the same time, the structural requirements of lifting and installation of the block should be considered. And now the current proportion of the hole grid is mostly between 30% to 40%.

3. Block foundation

The general weight of a fence slab is relatively large, and it is not enough to maintain balance by relying on its own stable weight. It is usually required to be set on a stable foundation, generally using the prism instead of the foundation, so it requires the prism to be stable and reliable. If the prism is built by stones, the stone size and weight should be determined by calculation.

Main Feature

1. Fence slab is a large overall structure, covering a large area.

2. Fence slab and other artificial special-shaped block ratio, give full play to the characteristics of the strength of concrete, it with the strength of concrete to resist the wave force, but also with reinforcement, give full play to the tensile and compressive strength of the material, so that the fence slab's rib and side beam become thinner, save more material than other special-shaped concrete block.

3. From the appearance, the slope is smooth and beautiful. Especially suitable for the bank protection of factory and tourist area. Strong adaptability to the curved surface of the revetment, in the corner can also be made into a circular arc fence slab.

4. The precast process of the fence slab is simple and the project progress is fast, which is conducive to resisting the harsh hydrological and meteorological environment during the construction period. Installation one I-block can only cover less than 1 square, but one fence slab can cover 5 ~ 20 square meters. Especially in the slope leveling, in urgent need of slope protection, fence slab structure can show the unique superiority.

Application Scenario

The fence slab has been used in many projects in Dalian, Qingdao and other areas. And its practical value has been obviously shown. For example, the breakwater of Beihai Shipyard of the Ministry of Communications has a top elevation of 7.5m and a wave height of 5.0m, which is designed to surmount the waves. The underwater slope was originally protected by 1.2m thick dry masonry bar, but later it was changed to fence slab due to the difficulty in mining bar stones and the high price. Completed in 1973, after several years of on-site observation, the structure of the fence slab is stable, especially withstanding the attack of the typhoon No. 2 of the year, the typhoon lasted for as long as three days, and the waves were higher than the embankment. Although the waves were serious, but the stability of the embankment slope protection is safe and sound.

Another example is the South bank protection project of Dalian No.7 Petroleum Plant. The total length of the bank protection is 535m, the designed wave height is 4.2m, and the fence slab is used to protect the bank. When 333m of fence slabs were applied to the bank, and the bank suffered a typhoon, and the wave height is higher than 4m. Finally the embankment which had been protected by the fence slab was intact, but the whole embankment which was not protected by the surface was destroyed. This fully shows that the fence slab can play a good protective role under the action of waves.