1. Surface runoff drainage method
1. Runoff drainage is used for the drainage of stands, area 1 and plastic runway. This method can also be used for football fields, small competition venues, and training grounds with low drainage requirements.
2. The ground in the runoff area must be flat and the slope must be uniform. The slope of the competition venue is shown in Table 12.2.1-7, and the slope runoff of 0.5%~1% on other ground is directed to the drainage ditch.
3. The width of the annular drainage ditch is generally 0.4~0.6m, and the longitudinal slope in the ditch is generally 2‰~3‰. The outer open ditch should be made of the grille cover plate, and the inner open ditch surface should be provided with water inlet. The open ditch method is shown in Figure 12.2.2-2.
Second: the combination of drainage and seepage
(1) The drainage combined with drainage method is used for the drainage of the lawn of the football field, and the ballast track can also be used for this method.
(2) The football field generally adopts a 5‰ fishback slope slope to the inner annular drainage ditch, and the slope of the blind ditch drainage pipe should be consistent with the slope of the field. The conventional blind ditch arrangement is shown in Figure 12.2.2-3 (a, b, c).
(3) A seepage layer should be set under the lawn of the football field, and the filter material should be neat and distinct. The type of filter material, particle size ratio, and thickness of the filter layer are all related to the type of turf on the site, and are generally provided by the turf supplier. The common distribution practices of seepage layers in football fields are shown in Figure 12.2.2-4
(4) The blind ditch with filter tube is preferred, and the blind ditch without filter tube can also be used. The general practice of blind ditch is shown in Figure 12.2.2-5.
(5) The diameter of the blind ditch drainage filter pipe is DM100~DN150, and its spacing is 5~10m. The outer wall of the drainage filter pipe should be wrapped with a coarse nylon mesh to prevent fine sediment from entering the inner ring ditch.
Three: Forced rapid drainage mode
(1) The forced rapid drainage method is to apply negative pressure to the drainage blind pipe below the lawn gradation layer through a vacuum pump, so as to increase the hydraulic slope of water infiltration in the soil of the site after rain, so as to speed up the drainage speed of the site. It is suitable for hosting the Olympic Games, Asian Games and world-class competition venues.
(2) The system is composed of a vacuum pump, a gas-water separator, a blind pipe and an electric valve. It has the dual functions of forced suction drainage and self-flowing drainage. When it is necessary to remove the stagnant water in time in the heavy rain, close the artesian drainage valve and start the vacuum pump to achieve negative pressure forced drainage. In the event of light rainfall or no special competition requirements, the seepage water on the field will be drained artesianly through the slope of the blind pipe.
(3) The site drainage pipes are set up in two stages. The primary pipe is made of DN80 permeable pipe, wrapped with a layer of 50g/m2 non-woven fabric, and the secondary pipe is made of DN200 pressure-bearing plastic pipe, which is connected to the vacuum pump. The buried depth of the primary pipe is 0.45~0.6m, the buried depth of the secondary pipe is 0.6~0.95m, and the pipe spacing is 2~5m. The pipes need to be equipped with a degree of 2‰~5‰ to meet the requirements of self-flow drainage. The layout of the forced drainage pipeline is shown in Figure 12.2.2-6.
(4) The vacuum pump should be located in the machine room, and the vacuum pump should be connected to the site drainage blind pipe after passing through the air-water separator. The negative pressure vacuum of the vacuum pump should be controlled at 0~0.01MPa.
(5) System control: When the lawn is 30mm thick, close the electric valve of the artesian pipeline, open the electric valve of the forced drainage pipeline, and start the vacuum pump at the same time to carry out negative pressure forced rapid drainage of the site. When the water on the lawn drops to 100mm under the lawn, the electric valve at the beginning of the pipe network is opened to replenish the air to the pipe network, which plays a role in loosening the soil layer and preventing compaction. The control relationship between the vacuum pump and each valve is shown in Figure 12.2.2-7 and Table 12.2.2-2.
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