In the standards of China's construction industry, a building with a clear height of more than 100 meters can be called a super high-rise building. High-rise buildings are often a synthesis of various functions, and their main features include: buildings often carry more complex and diverse functions; Usually, buildings include office buildings, hotels, shopping malls, restaurants, entertainment and leisure places. It can be seen that high-rise buildings are complex in function and structure, and the design of water supply and drainage system of such buildings needs to consider all aspects. Combined with some existing water supply and drainage design samples of high-rise buildings in China, the characteristics are summarized as follows: (1) In high-rise buildings, the pressure caused by still water is often much higher than that of ordinary buildings. If water is supplied in a single area in design like a common building, on the one hand, it will affect users' use, on the other hand, it will also put greater pressure on pipelines, pipe fittings and other equipment and reduce their service life.
Therefore, in the choice of specific water supply mode, zoning should be carried out on the basis of accurate calculation to reduce the water pressure of the system and maintain the normal reliability and service life of the system. (2) In high-rise buildings, because there are many residents, they are also faced with large displacement and long pipes, which easily leads to unpredictable pressure in the pipes. Therefore, in the design of water supply and drainage system, we should pay full attention to the improvement of drainage system capacity, and try our best to keep the pipeline pressure stable and the pipeline water seal reliable. Therefore, it is suggested to introduce vent pipe into its drainage system and adopt single riser mode in combination with some advanced models abroad. In the selection of pipeline materials, we should pay attention to the mechanical strength of materials, while in the selection of pipeline interface materials, we should try our best to choose flexible interfaces. (3) Due to the large number of users, high-rise buildings are also facing great displacement. If there are incidents such as blocking pipes and stopping water supply, the impact will be great. Therefore, the reliability of water supply and the smoothness of drainage should be ensured in the design scheme. (4) High-rise buildings have more power equipment than ordinary buildings because of their large water consumption and long pipelines. Excessive noise and vibration that disturb people should be avoided during design.
2 High-rise building water supply and drainage system analysis
In this part, combined with some advanced domestic high-rise building water supply and drainage design cases and the author's practical experience, the system is analyzed in detail.
2. 1 Design and analysis of water supply system The water supply modes of high-rise buildings can be divided into parallel series and series series series; In the choice of specific equipment, it can also be divided into two categories, water tank and water pump. Combined with some typical high-quality engineering examples, the mode of water supply system is summarized. Some design elements are analyzed as follows:
Analysis of (1) series-parallel combined mode water supply
According to the design standards, high-rise buildings are equipped with refuge floors. In the specific design, high-level water tank devices can be installed in these parts. According to statistics, at present, many buildings with a height of more than 400 meters often choose series water supply. This method has its inherent advantages, that is, it significantly reduces the use of vertical risers, so it can greatly reduce the number of tube wells, save room area and reduce the pressure of water pumps and other equipment, so the reliability of the whole system is obviously improved and the investment is also saved. In this case, special attention should be paid to controlling the effective pressure range of the system at an acceptable level when designing, so the pressure reducing valve is essential. At this time, we should pay attention to the failure of the pressure reducing valve, because once it fails, it is easy to cause series pressure, which has a great impact on the operation of the pipe fittings, so we should set a suitable height for each partition in the specific design. For the parallel water supply mode, the feed pump equipment is often arranged in the basement of the building, so it has little influence on the occupation of the building area, and each partition can be independent of each other. In addition, the location of parallel equipment is often concentrated, which provides a lot of convenience for the maintenance and management of equipment. However, it should be noted that there are more risers in parallel, so the pressure of high-pressure pump in the system is higher. Therefore, it is necessary to comprehensively consider the arrangement of the refuge floor of the building and increase the delivery pump in the parallel system. To sum up, the combination of series and parallel is a way recommended by the author.
(2) Design and analysis of decompression device.
In the water supply and drainage system of high-rise buildings, necessary pressure reducing valves must be set. Although the function of pressure reducing valve can not be ignored, it belongs to mechanical equipment in essence, so it has a certain failure rate. On the premise of practical conditions, the author suggests controlling the number of pressure reducing valves as a whole, such as configuring water tanks and pumps on some floors. Taking Shanghai Center as an example, in the design of its water supply system, except some floors need to be used for sightseeing, the water supply mode is based on frequency converter, and most of them are pumps and water tanks. In the selection of series and parallel connection, the combination of series and parallel connection is introduced. It can be seen that in the water supply system design of Shanghai Financial Center, the number of pressure reducing valves should be reduced as much as possible.
(3) High water tank and variable frequency pump
In super-high-rise buildings, the design of water supply and drainage system must involve high-level water tank and feed pump, but with different design objectives, their concerns are different. The water supply device that supplies water through the high-level water tank stores the water needed by residents in the high-level water tank, and then distributes it to various water-using places according to the water demand. In the water supply mode based on variable frequency pump, the whole system is divided into delivery pump and water supply variable frequency pump according to its specific functions. The former is used to supply high-level water tanks, and the latter is used to supply water points. Among them, in the series water supply mode, a delivery pump must be set up. In high-rise buildings, the design of water supply variable frequency pump is particularly important. For high-rise buildings, safety should be considered. In this context, the author suggests that the number of pressure reducing valves should be controlled in the design. Taking Nanjing Zifeng Building as an example, the comprehensive water supply mode of high-level water tank and water pump is adopted, which has the advantage of saving construction area. In addition, the water supply area through variable frequency pump often belongs to the floor with low water pressure, so the purpose of saving water can be achieved. However, it should also be considered that the high-rise guest room area often requires high stability of water supply, and the disadvantage of variable frequency pump is insufficient stability. However, Shanghai Financial Center adopts the mode of series connection and parallel connection. Although it covers a large area, it can greatly improve the stability of water supply.
2.2 Design and analysis of drainage system
(1) water pipe pressure analysis
There are obvious differences between drainage pipes and rainwater pipes. The former shows non-full flow, while the latter shows full flow. Considering that both the drainage pipe and the rainwater pipe are not pressure systems, it is impossible to calculate their actual pressure grade in combination with the pipe height when calculating their bearing capacity. If the pipe diameter is about 150mm, when the pipe length is close to 100 m, the pressure is often higher than 0. 1 1 MPa. Under this pressure, foreign bodies in the pipeline can be washed away. Combined with the design models of some high-rise buildings in China, pipes with strong compression resistance are often used. For example, Shanghai Financial Building uses thick steel pipes, while Chongqing Financial Center uses plastic-lined steel pipes.
(2) Analysis of drainage mode of single riser
The application scope of single riser drainage method is often limited to: some bathrooms have limited area, such as residential buildings, hotels, and some environments that are very sensitive to low noise emission. For high-rise buildings, the height is often very high, and the building area of each floor is limited, so the area of tube wells should be minimized in the design. In this case, the single riser drainage mode can be selected. On the one hand, it can achieve satisfactory drainage capacity, on the other hand, it can also reduce the noise of water flow. It should be noted that when designing multiple converging risers, special joints should be provided for them. In the existing engineering examples, Shanghai Financial Building adopted the single riser drainage method, and achieved satisfactory results. The drainage was timely and smooth, and the smell and noise did not affect the residents.
3 high-rise building water supply and drainage system design case analysis
Combined with case analysis, the water supply and drainage system of a high-rise building is designed. Located in Chengdu, the project is a multi-functional comprehensive high-rise building integrating hotels, office buildings and shopping centers. The building has 2 floors underground and 28 floors above ground. Underground garage and equipment room, building clear height of 98.5 meters.
3. 1 water supply system design
The municipal water supply pressure of the building is 0.4 MPa, so in order to make full use of the water pressure under the concept of energy saving, the municipal water supply from the second floor underground to the sixth floor above ground is selected. The frequency converter is introduced into the seventh floor and above to realize water supply. Divide the whole water supply system, and the water supply mode introduced from the seventh floor to the nineteenth floor is low-area inverter; High-frequency converters are selected for floors 20 to 28. According to statistics, there are 659 households in this building, with an average daily water consumption of 670 cubic meters. Therefore, a 170 cubic meter water storage tank is designed, which is divided into independent parts.
3.2 Design of drainage system
In the design of sewage and wastewater, the sewage and wastewater from buildings are discharged by combined system, and all the sewage and wastewater generated by households are led to municipal sewage pipe network facilities after passing through centralized septic tanks; The second and third floors of the building belong to the dining area of the hotel, and the wastewater sent by it is standardized in the oil tank before being discharged into the municipal sewage pipe network. The wastewater below the ground is erected by a special water pump and injected into the sewage pipe network. In the specific design, in order to save energy and safety, the collecting well was optimized and reformed. The usual design mode is to arrange a relatively independent collecting well near the fire ladder of the building. Considering that there is no civil air defense in the basement of the building designed in this paper, if the collecting well is arranged near the elevator, it can only reduce the height of the elevator platform and increase the design cost. In this case, the collecting well is optimized, transplanted to the garage and merged with the special collecting well for the garage.
The elevator and garage belong to the same area of the fire zone, and the elevator and garage are designed as Class A fire doors. In order to maintain fire safety, the drainage pipe of the collecting well is laid under the submersible pump. In addition, the design also focuses on whether the wastewater risers in the residents' toilets and kitchens are set separately. In the standard of residential code, these two types of pipes should be designed and set separately, and in this building, these separated drainage risers began to merge into one when they extended to the transfer floor. At the same time, how to connect the branch pipe and riser at the bottom of the household is also considered. The general engineering design method is to add an independent drainage pipeline to the pipeline design at the bottom of the household, and at the same time set up a ceiling extension ventilation device for it. This scheme also has some disadvantages, that is, the number of pipes on the facade is obviously increased, which reduces the aesthetics, increases the project cost and occupies indoor space. Another method is to set a check valve on the drain pipe used in the kitchen on the ground floor of the building, and design the position of this branch pipe into the kitchen cabinet to provide convenience for maintenance. Combined with the above analysis, the rigid PVC pipe is finally selected for the sewage and wastewater riser of this project.
4 conclusion
In the design of high-rise buildings, water supply and drainage system is a key part. The design quality of water supply and drainage module is closely related to the experience and life of building residents, so the design in this aspect pays great attention to its practical function and energy saving. Architectural engineering designers should fully follow the design specifications of high-rise buildings, learn from successful engineering experience, and actively introduce new technologies that are conducive to safety and reliability, so as to improve the overall technology, energy saving and safety level of China's construction industry.
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