Natural pool is also calledpond, pond refers to a laketinyWater body.The method of defining ponds and lakes is controversial.Generally speaking, ponds are too small to be crossed by boats.Another definition is that people can cross safely without being completely flooded, or the water is so shallow that the sun can reach the bottom of the pond.The term pond may also be used only forartificialBuilt pool.
In any case, the pond usually has no ground inlet.They all rely on natural underground water sources and rainwater or use artificial methods to draw water into the pool.Because of this, the closed pondecosystemAll followlakeDifferent.The water in the pool is always green because there are many algae in it.
In Asia, ponds are commonly found incourtyard, within the community;In Europe, ponds are often found incastleinIn Canada, water resourcesrich, ponds are common.
According to its terrain and soil conditions, it can be built on the ground or underground, that is, it can be divided into open type and closed type. According to its shape characteristics, it can also be divided into circular and rectangular types. Due to different building materials, it can be divided into brick pool, masonry pool, concrete pool, etc.The layout principle of water pool is basically the same as that of water cellar.
Structural construction
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（1） Design requirements for pool structure
In addition to meeting the above design requirements for water storage works, the following requirements shall also be considered in the design of pool structure:
1. Load combination: the seismic load is not considered, only the dead weight, water pressure and earth pressure of the pool are considered.For the open pool, the load combination is that the pool is full of water and there is no soil outside the pool;For the closed pool, the load combination is no water in the pool and soil outside the pool.During calculation, the unit weight of mortar masonry and concrete is 2.4t/m.For underground water tank, the backfill outside the tank wall is required to be compacted. When calculating the earth pressure, the volume weight of the backfill is 1.8t/m, and the internal friction angle is 30 °.
2. The allowable foundation bearing capacity shall be calculated according to the geological conditions. If the actual bearing capacity of the foundation cannot meet the design requirements or the foundation will cause uneven settlement, effective foundation treatment measures must be taken before the construction of the pool.The foundation of the bottom plate of the pool shall have sufficient bearing capacity, be flat and dense, or be paved and compacted with crushed stone (or coarse sand).
3. The pool shall be designed as standard as possible, or as per Grade V buildings and relevant specifications.The bottom and side wall of the pool can be made of mortar masonryplain concreteorreinforced concrete。Brick masonry can also be used in areas where the average temperature of the coldest month is higher than 5 ℃, butcement mortarPlastering.When mortar masonry is used at the bottom of the pool, it shall be built with mortar. The mortar grade of the pool shall not be less than M10, and the thickness shall not be less than 25cm.When concrete is used, the grade should not be less than C15, and the thickness should not be less than 10cm.The soil foundation shall be overturned and tamped, and the depth shall not be less than 40cm.The size of pool wall shall be calculated and determined according to the standard design or specification requirements.
4. The foundation of the pool is very important, especiallyCollapsible loessIf there is slight leakage in the area, the project safety will be endangered.Therefore, the integral reinforced concrete or plain concrete pool shall be preferred for the pool built on collapsible loess.When the foundation soil is weak collapsible loess, the bottom of the pool shall be turned over and tamped to a depth of not less than 50cm;If the foundation soil is medium or strong collapsible loess, the depth of overturning and tamping shall be increased, and measures such as immersion and pre settlement shall be taken.
5. Ladders should be set in the pool, sewage pipes should be set at the bottom of the pool, desilting manholes should be set in the closed pool, and guardrails should be set in the open pool, which should have sufficient strength and height not less than 1.1m.
（2） Pool structure characteristics
1. Open circular pool
The open pool body is composed of the pool bottom and the pool wall.Most of them are seasonal pools, which do not have the functions of anti freezing and anti evaporation.The circular pool structure has good stress conditions. Under the same water storage capacity, the construction materials used are less and the investment is less.The foundation bearing capacity of the open circular masonry pool is designed as 10 t/m, the pool floor is C15 concrete, the thickness is 10 cm, and the pool wall is M7.5 masonry, the thickness is determined according to the standard design or relevant specifications according to the load conditions. Table 2 lists the main dimensions, quantities and material consumption of the open circular masonry pool for reference.
2. Open rectangular pool
The composition, ancillary facilities and wall structure of the rectangular pool are basically the same as those of the circular pool, except that the circular pool is changed into a rectangular pool according to the terrain conditions.However, the structural stress condition of rectangular pool is not as good as that of circular pool, and the corner is a weak link, so preventive and reinforcement measures should be taken.When the storage capacity is within 60m, its shape is similar to a square layout. When the length width ratio of the pool exceeds 3, a partition wall needs to be arranged in the middle to prevent the side wall from losing stability due to excessive lateral pressure. In this way, one pool is divided into two, and a water outlet is reserved on the upper part of the partition wall, which can effectively precipitate sediment.Figure 3-12 is the structural diagram of the open rectangular pool. The pool bottom is made of C19 concrete, with a thickness of 20cm, and the column is made of C19 concretereinforced concreteThe tank wall is 24cm thick brickwork, M10cement mortarThe plastering is impervious, 3cm thick, and the top cover of the pool body is made of concrete hollow slab.
3. Closed circular pool
Most of the closed pool body is located below the ground, which increases the effect of anti freezing and thermal insulation. The thickness of thermal insulation and anti freezing layer shall be determined according to the local climate and the maximum depth of frozen soil layer, so as to ensure that the pool water will not be frozen and damaged by frost heave.The structure of the closed pool is more complex and the investment is increased. The top of the pool is mostly made of thin shell concrete arch plates or rib arches to reduce the load and save investment.The depth diameter ratio of the closed cylindrical concrete pool in Gansu Province ranges from 1.2 to 1.8. The bottom of the pool is inverted arch and pavedNotoginseng lime soil30cm thick, 10cm thick concrete is poured on it, and the pool wall iscast-in-place concrete10 cm thick, and the concrete surface is plastered with a layer of cement mortar to strengthen the seepage prevention.Cover plate is made of wire meshprecast concrete , label C18.The tank neck is plastered with brickwork cement mortar.
The rectangular pool has strong adaptability. Different specifications, sizes and structural forms are required for the terrain and water storage capacity, and the water storage capacity varies greatly.The bottom of the closed rectangular pool is made of M7.5 cement mortar masonry, with a thickness of 40cm. C19 concrete is poured on it, with a thickness of 15cm. The pool wall is made of concrete, with a thickness of 15cm. The top cover is made of concrete hollow slab, and the furnace slag insulation layer is laid on it, with a thickness of 1.0m. The overburden layer is 30cm thick. Ladders and related ancillary facilities are also provided.
（3） Mobile support pool
With the progress of science and technology and the development of domestic economy, the pools that need infrastructure construction can no longer meet the requirements of social and economic development. People have developed new support pools. These portable support pools can be used in temporary water places, such as exhibition halls, sports grounds, swimming pools, squares, etcAnimation Water WorldInside, these pools are composed of steel frames and screened polyether polyethylene PVC fabric, hence the nameSupport pool。The height is between 60cm and 150cm, and the length and width are between 2x2m and 50x50m.
