Design method of rainwater and sewage diversion drainage pipeline

Abstract

The invention relates to the technical field of municipal official website construction, and particularly discloses a design method of a rainwater and sewage diversion drainage pipeline, according to the design method, a drainage area is divided into a plurality of catchment areas, a plurality of drainage pipelines are designed in each catchment area, and the drainage pipelines comprise rainwater pipelines and sewage pipelines which are independently arranged; according to the method, a rainwater pipeline and a sewage pipeline are designed respectively, in the rainwater pipeline displacement design, the rainwater pipeline displacement of each catchment area is designed and determined according to multiple design parameters of the rainwater pipeline, and the rainwater pipeline displacement of each catchment area is determined according to the specific implementation content of the rainwater pipeline. Through calculation, it is verified that the implementation content of the rainwater pipeline meets the designed and determined requirement for the drainage amount of the rainwater pipeline, the drainage capacity of the sewage pipeline is designed, calculated and verified in the same mode, and it is ensured that the drainage capacity of each catchment area meets the requirement; the rainwater and sewage diversion drainage pipeline meets the rainwater and sewage discharge requirements of preset municipal road areas, environmental pollution and water resource environmental pollution are reduced, and the urban inland inundation risk is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline engineering, and in particular to a design method for a rainwater and sewage diversion drainage pipeline. Background Art

[0002] As the infrastructure and lifeline to ensure the normal operation of the city, the underground drainage network is closely related to the daily life of residents and the urban environment. During the urban construction process, some municipal roads are not equipped with sewage pipes. The sewage in the municipal road area is mainly discharged after scattered discharge or simple treatment such as septic tanks. These discharge methods will cause certain pollution to the environment; the mixing of rainwater and sewage will also cause pipe siltation and blockage, affecting the city's flood control and drainage capabilities. During the rainy season, it is easy to have waterlogging on the road and sewage backflow, affecting the urban environment and residents' travel. Therefore, when setting up the underground drainage network, realizing the separation of rainwater and sewage is important for improving the treatment efficiency of the urban underground drainage network, protecting the environment and water resources, and improving the flood control and drainage capabilities of the urban environment.

[0003] The following problems exist in the design process of rainwater and sewage diversion drainage pipes: insufficient understanding of the geological conditions and topographical conditions of the construction site, failure to fully consider the installation of pipelines, and the drainage performance of rainwater and sewage diversion drainage pipes after installation; moreover, the fluid conditions of rainwater and sewage will also have a great impact on drainage. At the same time, due to the deviation between the design specifications and the actual implementation content, it will also affect the drainage effect of rainwater and sewage diversion; in addition, lack of consideration for high-intensity continuous precipitation makes it difficult for rainwater and sewage diversion drainage pipes to drain water in time, increasing the risk of urban waterlogging. Summary of the invention

[0004] At least one of the purposes of the present invention is to provide a design method for rainwater and sewage diversion drainage pipes in order to overcome the problems existing in the above-mentioned prior art. The design method divides the drainage area into multiple catchment areas, and arranges independent rainwater pipes and sewage pipes for each catchment area. When the drainage capacity of each catchment area meets the requirements, the rainwater and sewage diversion drainage pipes can meet the rainwater and sewage discharge requirements of the preset municipal road area, thereby reducing environmental and water resource pollution and reducing the risk of urban waterlogging.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention includes the following aspects.

[0006] A method for designing a rainwater-sewage separation drainage pipeline includes the following steps when designing a rainwater-sewage separation drainage pipeline for a drainage area: Step A: Divide the drainage area into multiple catchment areas, and design multiple drainage pipes for each catchment area, including independently arranged rainwater pipes and sewage pipes; Step B: Design and determine the drainage volume of the rainwater pipe in each catchment area based on multiple design parameters of the rainwater pipe; Step C: Determine the specific implementation content of the rainwater pipe according to the drainage volume of the rainwater pipe; Step D: Verify through calculation that the implementation of the rainwater pipe meets the rainwater pipe discharge volume determined by the design; Step E: Calculate the sewage volume in the catchment area based on multiple design parameters of the sewage pipe; Step F: According to the discharge volume of the sewage pipe, determine the implementation content of the sewage pipe so that it meets the design comprehensive sewage volume requirements of each catchment area; Step G: Verify through calculation that the implementation of the sewage pipe in the catchment area meets the sewage pipe discharge volume determined by the design; The steps BD and EF can be interchanged as a whole.

[0007] By dividing the drainage area into multiple catchment areas and arranging rainwater pipes and sewage pipes for each catchment area, when the drainage capacity of each catchment area meets the requirements, the rainwater and sewage diversion drainage pipes can meet the rainwater and sewage discharge requirements of the preset municipal road area; The design method of the above-mentioned rainwater and sewage diversion drainage pipes adopts the hierarchical design concept. The minimum level design is to ensure the drainage requirements within the drainage area within the range of 100-300 acres. For the drainage method of the next level, a drainage pipe system composed of multiple junctions (including rainwater pipes and sewage pipes) is designed. When the drainage capacity of multiple junctions meets the requirements, it can ensure that the drainage system within the range of 300-1000 acres will usually not have problems such as poor drainage and waterlogging.

[0008] At the same time, the design parameters of the rainwater pipe and the sewage pipe are fully considered during the design. The drainage pipe is made to meet the drainage requirements according to the design calculation. The implementation content of the rainwater pipe and the sewage pipe are determined respectively. The implementation content is calculated according to the actual situation during the construction process to further verify whether the drainage capacity of the drainage area meets the design requirements and further improve the drainage capacity.

[0009] Preferably, in step B, when designing the rainwater pipe, the multiple design parameters of the rainwater pipe include the rainwater pipe flow velocity, the rainwater pipe diameter and slope, the rainwater design recurrence period P, the comprehensive runoff coefficient Ψ and the rainfall duration t, wherein, among the rainwater pipe flow velocity, the maximum flow velocity Vmax=5m / s, the full flow flow velocity Vmin=0.75m / s, and among the rainwater pipe diameter and slope design parameters, the minimum pipe diameter of the connecting pipe between the rainwater inlet and the rainwater inspection well is not less than DN300, the slope i is not less than 0.01, the pipe diameter of the rainwater pipe in other parts is not less than DN800, the slope i is not less than 0.003, the rainwater design recurrence period P is not less than 3 years, and the comprehensive runoff coefficient Ψ is not less than 0.65.

[0010] The rainwater design return period P refers to the statistical time interval between two occurrences of the design rainstorm intensity in the rainwater drainage design. The flow runoff coefficient refers to the ratio of the runoff volume generated during the peak flow duration to the rainfall. Combined with the ultimate strength theory, the peak flow duration corresponds to the water collection time of the catchment area. The values ​​of the rainwater design return period P and the flow runoff coefficient are directly related to the size and consumables of the pipeline, which in turn affects the construction efficiency of the pipeline. The larger the diameter of the drainage pipeline, the more consumables the pipeline has, the lower the construction efficiency and the higher the cost. The rainwater design return period P value is set to at least 3 years, and the comprehensive runoff coefficient Ψ is designed to be no less than 0.65, which can not only ensure the drainage capacity of the pipeline, but also take into account the drainage volume during the peak rainfall, and avoid excessive design, which causes waste of pipeline drainage capacity.

[0011] Furthermore, the rainfall duration t includes the ground water accumulation time t1 and the rainwater flow time in the pipe t2, t=t1+t2. By considering the ground water accumulation time and the rainwater flow time in the pipe in the design, higher requirements are put forward for the design of rainwater pipes, avoiding poor drainage due to ignoring any one of rainwater accumulation on the ground or rainwater flow in the pipe, so as to achieve the purpose of sufficient and effective drainage.

[0012] Preferably, the drainage volume of the rainwater pipe is selected according to the rainstorm intensity q, and the rainstorm intensity q is selected according to the rainstorm intensity formula Calculated; where q represents the intensity of heavy rain, P represents the recurrence period of heavy rain, the recurrence period of heavy rain is once in three years, t represents the duration of design rainfall, which is selected according to the length of the rainwater pipe network and the size of the catchment area, t=t1+ t2(min), t1 represents the ground water collection time, t2 represents the rainwater flow time in the pipe, t1 is 15min to 20min, and t2 is determined according to the flow velocity calculation.

[0013] Preferably, the designed diameter of the rainwater pipe is DN300. The rainwater pipe is spliced ​​together by multiple rainwater pipe sections. Each rainwater pipe section adopts Grade II reinforced concrete pipe. Two adjacent pipe sections are connected by socket joints and sealed with rubber rings. A 180° gravel foundation is set at the bottom of the connection part of the rainwater pipe section, and the connection part is reinforced with 360° concrete full package. The slope of the rainwater pipe is not less than 1%.

[0014] The above-mentioned design and connection method of the rainwater pipe joint can ensure the safe operation of the rainwater pipe and avoid damage to the rainwater pipe at the connection part, which may lead to pipe burst. The socket connection structure is convenient for mass production of rainwater pipes and construction, which improves the construction efficiency of rainwater pipes. Setting a slope of not less than 1% can ensure the flow rate of the rainwater pipe and avoid the problem of waterlogging caused by long drainage retention time in the pipe.

[0015] Furthermore, when the diameter of the rainwater pipe is greater than DN2000mm, the rainwater pipe adopts a C30 reinforced concrete box culvert, and a 10-20cm thick C20 plain concrete cushion layer is laid at the bottom of the box culvert, and a 20-30cm thick medium-coarse sand foundation is also provided at the bottom of the plain concrete cushion layer.

[0016] The reinforced concrete box culvert structure can meet the requirements of the rainwater pipe on the pipe diameter size. At the same time, the method of setting a plain concrete cushion layer and a medium-coarse foundation from top to bottom at the bottom of the box culvert can ensure the safety of the installation and operation of the rainwater pipe of the reinforced concrete box culvert structure, and avoid settlement or hard contact with the bottom of the box culvert that affects the safety of the pipe connection.

[0017] Furthermore, the cross-sectional shape of the box culvert is in the form of a circular ring or a square ring structure.

[0018] For step E, the urban design comprehensive sewage volume calculation formula is used. Multiple design parameters of the sewage pipe are determined according to the drainage area, including the maximum daily water consumption index Qi[ m³ / (hm 2 .d)], different types of land use scale (hm 2 ), sewage discharge coefficient k1, daily water supply variation coefficient k2, groundwater infiltration rate k3, total sewage volume variation coefficient Kz, the urban design comprehensive sewage volume calculation formula is Q=∑k1×Qi× k2×k3×Ai / 24 / 3600×Kz.

[0019] In this embodiment, for drainage areas, the water consumption index method of different types of land use is used to calculate the sewage volume. The domestic sewage volume is 90% of the total water consumption, and the industrial wastewater is 80% of the total water consumption. In addition, the infiltration of 5-30% of groundwater is considered. Therefore, the groundwater infiltration rate k3 is 1.05~1.3, and this embodiment takes 1.1. The daily variation coefficient k2 of urban water supply ranges from 1.1 to 1.5, and this embodiment takes 1.3. The sewage discharge coefficient k1 takes 0.8 / 0.9, and the sewage pipe adopts gravity flow, which is a non-full flow form of circular pipe. The value of the total sewage variation coefficient Kz is determined and selected according to the average daily flow rate of sewage (L / s).

[0020] The minimum design flow rate of the sewage pipe is 0.6m / s at the design fullness, and the maximum design flow rate is 5m / s. When crossing the regional river, an inverted siphon is set up, and the flow rate of the inverted siphon is greater than 0.9m / s and greater than the flow rate in the inlet pipe.

[0021] In the step F, when determining the implementation content of the sewage pipe according to the drainage volume of the sewage pipe, it also includes calculating the sewage pipe flow rate according to the design slope of the sewage pipe, and adjusting the sewage flow rate to within the economic flow rate range, and then determining the pipe diameter according to the flow rate, and calculating the sewage discharge capacity of the sewage pipe by the sewage flow rate, the slope of the sewage pipe and the fullness, to ensure that the designed sewage pipe meets the sewage pipe drainage volume requirements determined by the design.

[0022] Furthermore, the sewage pipe flow rate is calculated using the following formula: ; In the formula, n is the roughness coefficient. The roughness coefficient of reinforced concrete pipes is n=0.013, and the roughness coefficient of plastic pipes is n=0.011. When pipes of other materials are selected as sewage pipes, the roughness coefficient of rainwater pipes needs to be adjusted.

[0023] The minimum design flow rate of the sewage pipe is 0.6m / s at the design fullness, and the maximum design flow rate is 5m / s. When crossing the regional river, an inverted siphon is set up, and the flow rate of the inverted siphon is greater than 0.9m / s and greater than the flow rate in the inlet pipe.

[0024] Furthermore, by carrying out the above-mentioned hydraulic design for urban areas, and designing rainwater pipes and sewage pipes for the main pipes for the confluence pipes in each drainage area, waterlogging in urban areas can be effectively avoided.

[0025] Preferably, the steps B to D specifically include the following steps: Step BD1: Design and arrange multiple groups of drainage pipe sections in multiple catchment areas, and obtain the spacing between two adjacent pipe sections in each group of pipe sections, and obtain the water collection time t1 based on the spacing, and at the same time determine the flow velocity v (m / s) in the rainwater pipe according to the design slope of the pipe section, and determine the water flow time t2 in the rainwater pipe based on the flow velocity calculation; Step BD2: Determine the catchment area F (ha) based on the distance between each pipe section and the service area of ​​the pipe section; Step BD3: Select and determine the comprehensive runoff coefficient Ψ, and thereby obtain the total runoff in the catchment area of ​​each pipe section; Step BD4: According to step BD1, the design flow of each pipe section in each rainwater pipe under the rainstorm intensity is calculated; Step BD5: Determine the diameter, slope and flow rate of each pipe section in the rainwater pipe, calculate the maximum water delivery capacity of each pipe section, and verify whether the maximum water delivery capacity of the pipeline meets the design flow requirements in step BD.

[0026] The design flow value of each pipe section is determined based on the size of the service area of ​​the pipe section, and the maximum water delivery capacity of the pipe is obtained through parameters such as the pipe diameter, slope and flow velocity. When the maximum water delivery capacity of the pipe meets the design flow requirements, the drainage capacity of the rainwater pipe can be guaranteed.

[0027] Furthermore, in step BD1, when the water flow time t2 in the rainwater pipe is determined according to the flow rate calculation, the following two methods are used to determine the water flow time in the pipe: the first method is to perform design calculations with twice the water flow time in the rainwater pipe; the second method is to increase the slope of the rainwater pipe and halve the water flow time in the rainwater pipe. In this way, the water flow time in the pipe is fully increased to reduce water retention and waterlogging caused by the slowdown of water flow speed during actual use, such as due to turbid water flow, which increases the viscosity of the water flow fluid and thus slows down the water flow speed.

[0028] Preferably, the steps E to G specifically include the following steps: Step EG1: Design and arrange multiple groups of sewage pipe sections in multiple catchment areas, and determine the length and service area of ​​the pipes in each group of pipe sections; Step EG2: According to the specific flow rate q0 of each pipe section, the sewage flow rate q1 is calculated. When there is a ring pipe section, the transmission flow rate q2 is calculated at the same time, and the total average flow rate is calculated to obtain the sewage design flow rate Q1´ of each pipe section; Step EG3: Design and determine the slope, pipe material, and fullness of each pipe section, and calculate the sewage design flow Q1 of each pipe section separately according to the highest daily water consumption index qi of different types of land use, the scale of different types of land use ai, and the total variation coefficient Kz; Step EG4: Determine the pipe diameter D, slope I, flow velocity V and slope height of each pipe section in the sewage pipe, and calculate the pipe water delivery capacity of each pipe section; Step EG5: Verify and compare the sewage design flow Q1´ obtained in each pipe section of the sewage pipe based on the total variation coefficient Kz and the total average flow (L / s) with the sewage design flow Q1 of each pipe section obtained in step EG3, and verify that the pipeline water delivery capacity obtained in step EG4 meets Q1´ in step EG3 and Q1 in step EG4, thereby verifying that the sewage flow requirements are met.

[0029] In step EG2, when there is a ring-shaped pipe section, the transfer flow is involved. The transfer flow refers to the sum of the corrected flows in each ring in the ring-shaped pipe network, and is related to the number of rings, the number of nodes and the number of pipe sections.

[0030] In summary, due to the adoption of the above technical solution, the present invention has at least the following beneficial effects: 1. By dividing the drainage area into multiple catchment areas, and arranging rainwater pipes and sewage pipes for each catchment area, when the drainage capacity of each catchment area meets the requirements, the rainwater and sewage diversion drainage pipes can meet the rainwater and sewage discharge requirements of the preset municipal road area. At the same time, the design parameters of the rainwater pipes and the sewage pipes are fully considered during the design. According to the design calculation, the drainage pipes meet the drainage requirements. The implementation content of the rainwater pipes and the sewage pipes are determined in general. The implementation content is calculated according to the actual situation during the construction process to further verify whether the drainage capacity of the drainage area meets the design requirements and further improve the drainage capacity; 2. According to the service area size of each section of the sewage pipe, the design flow value of the section is determined, and the water transmission capacity of the pipeline is obtained through parameters such as the pipe diameter, slope, flow velocity and slope drop. When the water transmission capacity of the sewage pipe meets (is greater than) the sewage design flow requirement, the drainage capacity of the sewage pipe can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a design flow chart of a rainwater and sewage diversion drainage pipeline according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments to make the purpose, technical solutions and advantages of the present invention more clearly understood. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] refer to Figure 1 The design method of the rainwater and sewage diversion drainage pipe of the exemplary embodiment of the present invention includes the following steps when designing the rainwater and sewage diversion drainage pipe for the drainage area: Step A: Divide the drainage area into multiple catchment areas, and design multiple drainage pipes for each catchment area, including independently arranged rainwater pipes and sewage pipes; Step B: Design and determine the drainage volume of the rainwater pipe in each catchment area based on multiple design parameters of the rainwater pipe; Step C: Determine the specific implementation content of the rainwater pipe according to the drainage volume of the rainwater pipe; Step D: Verify through calculation that the implementation of the rainwater pipe meets the rainwater pipe discharge volume determined by the design; Step E: Calculate the sewage volume in the catchment area based on multiple design parameters of the sewage pipe; Step F: According to the discharge volume of the sewage pipe, determine the implementation content of the sewage pipe so that it meets the design comprehensive sewage volume requirements of each catchment area; Step G: Verify through calculation that the implementation of the sewage pipe in the catchment area meets the sewage pipe discharge volume determined by the design; The steps BD and EF can be interchanged as a whole.

[0034] In step A, the rainwater pipes and sewage pipes arranged are newly added pipes. When renovating old network pipes, the available old network pipes should be included in the design scope of this embodiment. Before designing and arranging drainage pipes, the existing road layout information and underground drainage pipe network distribution information in the construction area are obtained, and new road design, new rainwater pipe design, and new sewage pipe design are carried out based on the obtained road layout information and underground drainage pipe network distribution information. In step B, when designing the rainwater pipe, multiple design parameters of the rainwater pipe include the rainwater pipe flow velocity, the rainwater pipe diameter and slope, the rainwater design recurrence period P, the comprehensive runoff coefficient Ψ and the rainfall duration t, wherein, in the rainwater pipe flow velocity, the maximum flow velocity Vmax=5m / s, the full flow flow velocity Vmin=0.75m / s, in the rainwater pipe diameter and slope design parameters, the minimum pipe diameter of the connecting pipe between the rainwater inlet and the rainwater inspection well is not less than DN300, the slope i is not less than 0.01, the diameter of the rainwater pipe in other parts is not less than DN800, the slope i is not less than 0.003, the rainwater design recurrence period P is not less than 3 years, and the comprehensive runoff coefficient Ψ is not less than 0.65.

[0035] The rainwater design return period P refers to the statistical time interval between two occurrences of the design rainstorm intensity in the rainwater drainage design. The flow runoff coefficient refers to the ratio of the runoff volume generated during the peak flow duration to the rainfall. Combined with the ultimate strength theory, the peak flow duration corresponds to the water collection time of the catchment area. The values ​​of the rainwater design return period P and the flow runoff coefficient are directly related to the size and consumables of the pipeline, which in turn affects the construction efficiency of the pipeline. The larger the diameter of the drainage pipeline, the more consumables the pipeline has, the lower the construction efficiency and the higher the cost. The rainwater design return period P value is set to at least 3 years, and the comprehensive runoff coefficient Ψ is designed to be no less than 0.65, which can not only ensure the drainage capacity of the pipeline, but also take into account the drainage volume during the peak rainfall, and avoid excessive design, which causes waste of pipeline drainage capacity.

[0036] Furthermore, the rainfall duration t includes the ground water accumulation time t1 and the rainwater flow time in the pipe t2, t=t1+t2. By considering the ground water accumulation time and the rainwater flow time in the pipe in the design, higher requirements are put forward for the design of rainwater pipes, avoiding poor drainage due to ignoring any one of rainwater accumulation on the ground or rainwater flow in the pipe, so as to achieve the purpose of sufficient and effective drainage.

[0037] The drainage volume of the rainwater pipe is selected according to the rainstorm intensity q, and the rainstorm intensity q is selected according to the rainstorm intensity formula Calculated; where q represents the intensity of heavy rain, P represents the recurrence period of heavy rain, the recurrence period of heavy rain is once in three years, t represents the duration of design rainfall, which is selected according to the length of the rainwater pipe network and the size of the catchment area, t=t1+ t2(min), t1 represents the ground water collection time, t2 represents the rainwater flow time in the pipe, t1 is 15min to 20min, and t2 is determined according to the flow velocity calculation.

[0038] The designed diameter of the rainwater pipe is DN300. The rainwater pipe is spliced ​​by multiple rainwater pipe sections. Each rainwater pipe section adopts Grade II reinforced concrete pipe. The two adjacent pipe sections are connected by sockets and sealed with rubber rings. A 180° gravel foundation is set at the bottom of the connection part of the rainwater pipe section, and the connection part is reinforced with 360° concrete. The slope of the rainwater pipe is not less than 1%. The design and connection method of the rainwater pipe section can ensure the safe operation of the rainwater pipe and avoid damage to the rainwater pipe at the connection part, which may lead to pipe burst. The socket connection structure is convenient for mass production of rainwater pipes and construction, which improves the construction efficiency of rainwater pipes. Setting a slope of not less than 1% can ensure the flow rate of the rainwater pipe and avoid the problem of waterlogging caused by long drainage retention time in the pipe.

[0039] Furthermore, when the diameter of the rainwater pipe is greater than DN2000mm, the rainwater pipe adopts a C30 reinforced concrete box culvert, and a 10-20cm thick C20 plain concrete cushion layer is laid at the bottom of the box culvert, and a 20-30cm thick medium-coarse sand foundation is also provided at the bottom of the plain concrete cushion layer.

[0040] The reinforced concrete box culvert structure can meet the requirements of the rainwater pipe on the pipe diameter size. At the same time, the method of setting a plain concrete cushion layer and a medium-coarse foundation from top to bottom at the bottom of the box culvert can ensure the safety of the installation and operation of the rainwater pipe of the reinforced concrete box culvert structure, and avoid settlement or hard contact with the bottom of the box culvert that affects the safety of the pipe connection.

[0041] Furthermore, the cross-sectional shape of the box culvert is in the form of a circular ring or a square ring structure.

[0042] In the steps B to D, when designing the specific pipeline drainage capacity, a catchment area is used for illustration. The catchment area consists of three roads, named the first road, the second road, and the third road. The specific design calculation steps and the related parameters obtained are as follows: Multiple pipe sections are arranged in the first road. This embodiment uses 4 pipe sections as an example, namely YS1-YS2, YS2-YS3, YS3-YS4, and YS4-YS5. The distance between the YS1-YS2 pipe section and the previous pipe section is 180m, the distance between the YS1-YS2 pipe section and the YS2-YS3 pipe section is 198m, the distance between the YS2-YS3 pipe section and the YS3-YS4 pipe section is 261m, and the distance between the YS3-YS4 pipe section and the YS4-YS5 pipe section is 237m. According to the distance between the four pipe sections, the water collection time t1 of each pipe section is obtained respectively. The water collection time t1 of the YS1-YS2 pipe section is 15min, the water collection time t1 of the YS2-YS3 pipe section is 15.96min, the water collection time t1 of the YS3-YS4 pipe section is 15min, and the water collection time t1 of the YS4-YS5 pipe section is 15min. At the same time, according to the design slope of the pipe section and the pipe The length of the segment determines the flow velocity v (m / s) in the rainwater pipe. The value of the design slope can be selected according to the industry specifications. The water flow time t2 in the rainwater pipe is determined by calculating the flow velocity of each pipe segment. The corresponding water flow time t2 in the pipe of the YS1-YS2 pipe segment is 0.96min, the water flow time t2 in the pipe of the YS2-YS3 pipe segment is 1.67min, the water flow time t2 in the pipe of the YS3-YS4 pipe segment is 1.95min, and the water flow time t2 in the pipe of the YS4-YS5 pipe segment is 1.77min. The design calculation is based on twice the water flow time in the rainwater pipe. The 2×t2 time of the four pipe segments is 1.93min, 3.34min, 3.90min, and 3.54min respectively. According to the spacing between the four pipe sections and the service areas of the pipe sections, the corresponding increased catchment areas F (ha) of the four pipe sections are: the increased catchment area F of the YS1-YS2 pipe section is 3.51, the increased catchment area F of the YS2-YS3 pipe section is 3.82, the increased catchment area F of the YS3-YS4 pipe section is 4.86, and the increased catchment area F of the YS4-YS5 pipe section is 4.56; in order to avoid calculation, in this embodiment, it is assumed that not all pipe sections are new, and the cumulative catchment area of ​​the four pipe sections is equal to the increased catchment area. The comprehensive runoff coefficient Ψ of the four pipe sections is selected to be 0.65, and the cumulative catchment area, total runoff and design flow in the catchment area of ​​each pipe section are obtained: the cumulative increased catchment area Ψ.F of the YS1-YS2 pipe section is 2.28, the design flow q of the YS1-YS2 pipe section under heavy rain intensity is 302.06, and the YS The design flow rate of the 1-YS2 pipe section is 689.14 (L / s.ha), the cumulative increase in the catchment area Ψ.F of the YS2-YS3 pipe section is 4.76, the design flow rate q of the YS2-YS3 pipe section under the rainstorm intensity is 294.28, the design flow rate of the YS2-YS3 pipe section is 1402.09 (L / s.ha), the cumulative increase in the catchment area Ψ.F of the YS3-YS4 pipe section is 3.16, The design flow rate q of the S3-YS4 pipe section under the rainstorm intensity is 302.06, the design flow rate of the YS3-YS4 pipe section is 954.2 (L / s.ha), the cumulative increase of the catchment area Ψ.F of the YS4-YS5 pipe section is 2.96, the design flow rate q of the YS4-YS5 pipe section under the rainstorm intensity is 302.06, and the design flow rate of the YS4-YS5 pipe section is 895.30 (L / s.ha); Determine the diameter, slope and flow rate of the four pipe sections (pipe segments) in the rainwater pipe, and calculate the maximum water delivery capacity of each pipe section, which are: the diameter of the YS1-YS2 pipe section is 0.8m, the slope is 0.01, and the flow rate is 3.11 (M / s). After implementing this implementation content, the maximum water delivery capacity of the YS1-YS2 pipe section is 1562.78, which is much larger than the design flow value of the pipe section and meets the design flow requirements; the diameter of the YS2-YS3 pipe section is 1.0m, the slope is 0.003, and the flow rate is 1.98 (M / s). After implementing this implementation content, the maximum water delivery capacity of the YS2-YS3 pipe section is 1551. 98, which is greater than the design flow value of the pipe section; the diameter of the YS3-YS4 pipe section is 1.2m, the slope is 0.003, and the flow rate is 2.23 (M / s). After implementation according to this implementation content, the maximum water delivery capacity of the YS3-YS4 pipe section is 2523.69, which is much greater than the design flow value of the pipe section; the diameter of the YS4-YS5 pipe section is 1.2m, the slope is 0.003, and the flow rate is 2.23 (M / s). After implementation according to this implementation content, the maximum water delivery capacity of the YS4-YS5 pipe section is 2523.69, which is much greater than the design flow value of the pipe section; therefore, each pipe section (pipe section) meets the design flow requirements.

[0043] Similarly, the same method is used to design and calculate the multiple pipe sections arranged for the second road and the third road, and the obtained design flow and hydraulic calculation table are shown in Table 1 below.

[0044] Table 1 Design flow and hydraulic calculation table of other rainwater pipes

[0045] By performing design calculations on the YS5-YS6 pipe section, YS6-YS7 pipe section, YS7-YS8 pipe section, YS8-YS9 pipe section, YS9-YS10 pipe section, and YS10-YS11 pipe section respectively, it can be seen that each pipe section (pipe section) obtained by this design method meets the design flow requirements.

[0046] In this embodiment, the design flow value of each pipe section is determined according to the size of the service area of ​​the pipe section, and the maximum water delivery capacity of the pipe is obtained through parameters such as the pipe diameter, slope and flow velocity of the pipe. After calculation and implementation verification, when the maximum water delivery capacity of the pipe meets the design flow requirement, the drainage capacity of the rainwater pipe can be guaranteed.

[0047] When determining the water flow time t2 in the rainwater pipe based on the flow velocity calculation, another method can also be used to determine the water flow time in the pipe: by increasing the slope of the rainwater pipe, the water flow time in the rainwater pipe is halved. In this way, the water flow time in the pipe can be fully increased to reduce water retention and waterlogging caused by the slowdown in water flow velocity during actual use. For example, due to turbid water flow, the viscosity of the water flow fluid increases, thereby slowing down the water flow velocity.

[0048] For step E, the urban design comprehensive sewage volume calculation formula is used. Multiple design parameters of the sewage pipe are determined according to the drainage area, including the maximum daily water consumption index Qi[ m³ / (hm 2 .d)], different types of land use scale (hm 2 ), sewage discharge coefficient k1, daily water supply variation coefficient k2, groundwater infiltration rate k3, total sewage volume variation coefficient Kz, the urban design comprehensive sewage volume calculation formula is Q=∑k1×Qi× k2×k3×Ai / 24 / 3600×Kz.

[0049] In this embodiment, the sewage volume is calculated for the drainage area using the water consumption index method for different types of land use. The domestic sewage volume is 90% of the total water consumption, and the industrial wastewater is 80% of the total water consumption. In addition, 5-30% of the groundwater infiltration is considered. Therefore, the groundwater infiltration rate k3 is 1.05~1.3, and it is 1.1 in this embodiment. The daily variation coefficient k2 of urban water supply ranges from 1.1 to 1.5, and it is 1.3 in this embodiment. The sewage discharge coefficient k1 is 0.8 / 0.9. The sewage pipe adopts gravity flow, which is a non-full flow form of circular pipe. The fullness (h / d) of the sewage pipe is determined according to the pipe diameter or channel height. Under the design flow rate, the ratio of the water depth h of the sewage / water flow in the pipe to the pipe diameter (inner diameter) D is called the design fullness. Please refer to the following Table 2 for details.

[0050] Table 2 Maximum design filling degree (h / d) selection table

[0051] The total variation coefficient of sewage kz is a parameter commonly used in the design of urban sewage projects, which is used to describe the variation of sewage flow. It usually refers to the ratio of the maximum daily maximum hourly sewage volume to the average daily average hourly sewage volume in a year, that is, kz = Qmax / Qavg. Among them, Qmax represents the maximum daily maximum hourly sewage volume in a year, and Qavg represents the average daily average hourly sewage volume.

[0052] The value of the total sewage variation coefficient Kz is determined according to the average daily sewage flow rate (L / s): when the average daily sewage flow rate (L / s) is ≥5 L / s and <15L / s, the Kz value is 2.7; when the average daily sewage flow rate (L / s) is ≥15 L / s and <40L / s, the Kz value is 2.4; when the average daily sewage flow rate (L / s) is ≥40 L / s and <70, the Kz value is 2.1; when the average daily sewage flow rate (L / s) is ≥70 L / s and <100L / s, the Kz value is 2.0; when the average daily sewage flow rate (L / s) is ≥100 L / s and <200L / s, the Kz value is 1.9; when the average daily sewage flow rate (L / s) is ≥200 L / s and <500L / s, the Kz value is 1.8; when the average daily sewage flow rate (L / s) is ≥500 L / s and <1000L / s, Kz takes the value of 2.6; when the average daily sewage flow rate (L / s) ≥10000L / s, Kz takes the value of 1.5, and the situation where the average daily sewage flow rate is <5L / s does not exist (no-man’s land).

[0053] The water consumption indicators for different land uses are shown in Table 3.

[0054] Table 3 Water consumption index table for different types of land use 3 / (hm 2 ·d)] The total amount of sewage is obtained based on all relevant land types and areas in the drainage area. The minimum design flow rate of the sewage pipe is 0.6m / s at the design fullness, and the maximum design flow rate is 5m / s. When crossing the regional river, an inverted siphon is set up, and the flow rate of the inverted siphon is greater than 0.9m / s and greater than the flow rate in the inlet pipe.

[0055] In step F, when determining the implementation content of the sewage pipe according to the drainage volume of the sewage pipe, it also includes calculating the sewage pipe flow rate according to the design slope of the sewage pipe, and adjusting the sewage flow rate to within the economic flow rate range, and then determining the pipe diameter according to the flow rate, and calculating the sewage discharge capacity of the sewage pipe by the sewage flow rate, sewage pipe slope and fullness, to ensure that the designed sewage pipe meets the sewage pipe drainage requirements determined by the design.

[0056] A preferred implementation is that the sewage pipe flow rate is calculated using the following calculation formula: ; In the formula, n is the roughness coefficient, the pipe roughness coefficient of reinforced concrete pipe is n=0.013, and the pipe roughness coefficient of plastic pipe is n=0.011. When pipes made of other materials are selected as sewage pipes, the values ​​shall be selected according to the range shown in Table 4 below. Table 4 Roughness coefficient value reference table

[0058] It is worth mentioning that the roughness coefficient of the rainwater pipe can also be selected according to Table 4.

[0059] In the steps E to G, when designing the drainage capacity of a specific sewage pipe, the aforementioned catchment area is used for illustration, and multiple groups of sewage pipes are arranged in the catchment area formed by the first road, the second road, and the third road, respectively. The specific design calculation steps and the related parameters obtained are as follows: Multiple sewage pipelines are arranged in the first road. This embodiment is illustrated with two pipelines, namely WS1-WS2 and WS2-WS3. The pipeline length of the WS1-WS2 segment is 524m, and the service area (catchment area) of the WS1-WS2 segment is 8.52. Combined with the designed specific flow rate q0 of the WS1-WS2 segment, q0 is 1.2 (L / (s.ha)), and the sewage flow rate q1 of the WS1-WS2 segment is calculated to be 10.22 (L / s). Since WS1-WS2 has a ring segment, the transmission flow rate q2 of the WS1-WS2 segment is calculated to be 144.00 (L / s). The total average flow rate Q1´ is calculated to be 154.22 (L / s). The slope, pipe material, and fullness of the WS1-WS2 segment are determined by design. According to the highest daily water consumption index qi of different types of land use, the scale of different types of land use ai and the total variation coefficient K z, the sewage design flow Q1 of the WS1-WS2 pipe section is calculated separately as 243.44, and the implementation content of the WS1-WS2 pipe section in the sewage pipeline is determined, including the pipe diameter D is 600mm, the slope I is 0.5%, the flow velocity V is 1.59 (m / s), the slope height is 2.62m, and the fullness h / d is 0.65. The pipe water delivery capacity of the WS1-WS2 pipe section is calculated to be 292.22 (L / s); by verifying and comparing the sewage design flow Q1´ of the WS1-WS2 pipe section in the sewage pipeline based on the total variation coefficient Kz and the total average flow (L / s), the sewage design flow Q1 of the WS1-WS2 pipe section is 243.44, and the pipe water delivery capacity of the WS1-WS2 pipe section is 292.22 (L / s). The pipe water delivery capacity value of 292.22 (L / s) is greater than Q1´ and Q1, thereby verifying that the sewage flow requirements are met; The length of the WS2-WS3 pipe section is 410m, and the service area (catchment area) of the WS2-WS3 pipe section is 6.60. Combined with the designed specific flow rate q0 of the WS2-WS3 pipe section, q0 is 1.2 (L / (s.ha)), and the sewage flow rate q1 of the WS2-WS3 pipe section is calculated to be 7.92 (L / s). Since WS2-WS3 has a ring pipe section, the transmission flow rate q2 of the WS2-WS3 pipe section is calculated to be 168.00 (L / s). The total average flow rate Q1´ is calculated to be 175.92 (L / s). The slope, pipe material, and fullness of the WS2-WS3 pipe section are determined by design. According to the highest daily water consumption index qi of different types of land use, the scale ai of different types of land use, and the total variation coefficient Kz, the sewage design flow rate of the WS2-WS3 pipe section is calculated separately. The quantity Q1 is 273.77, and the implementation content of the WS2-WS3 pipe section in the sewage pipeline is determined, including the pipe diameter D is 600mm, the slope I is 4.8%, the flow velocity V is 1.78 (m / s), the slope height is 19.68m, and the fullness h / d is 0.65. The pipe water delivery capacity of the WS2-WS3 pipe section is calculated to be 27.13 (L / s); by verifying and comparing the sewage design flow Q1´ of the WS2-WS3 pipe section in the sewage pipeline based on the total variation coefficient Kz and the total average flow (L / s), the sewage design flow Q1 of the WS2-WS3 pipe section is 273.77, and the pipe water delivery capacity of the WS2-WS3 pipe section is 327.13 (L / s). The pipe water delivery capacity value of 327.13 (L / s) is greater than Q1´ and Q1, thereby verifying that the sewage flow requirements are met; Similarly, the second and third roads are designed and calculated in the same way, and the resulting design flow and hydraulic calculation table is shown in Table 5.

[0060] Table 5 Sewage hydraulic calculation table for other sewage pipes

[0062] By designing and calculating the WS3-WS4 pipe section, WS4-WS5 pipe section, WS5-WS6 pipe section, and WS6-WS7 pipe section respectively, it can be seen that each pipe section (pipe section) obtained by this design method meets the design flow requirements for sewage discharge.

[0063] The design method of the rainwater and sewage separation drainage pipe of the present embodiment can also be implemented on a larger scale. For example, by conducting hydraulic design for urban areas, and designing rainwater pipes and sewage pipes for the main pipes for the confluence pipes in each drainage area, the drainage confluence pipes can meet the rainwater and sewage discharge capacity in a larger range, which can effectively avoid waterlogging in urban areas.

[0064] The above is only a detailed description of the specific implementation of the present invention, rather than a limitation of the present invention. Various substitutions, modifications and improvements made by those skilled in the relevant art without departing from the principle and scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for a rainwater and sewage diversion drainage pipeline, characterized in that: When designing rainwater and sewage separation drainage pipes in the drainage area, the following steps are included: Step A: Divide the drainage area into multiple catchment areas, and design multiple drainage pipes for each catchment area, including independently arranged rainwater pipes and sewage pipes; Step B: Design and determine the drainage volume of the rainwater pipe in each catchment area based on multiple design parameters of the rainwater pipe; Step C: Determine the specific implementation content of the rainwater pipe according to the drainage volume of the rainwater pipe; Step D: Verify through calculation that the implementation of the rainwater pipe meets the rainwater pipe discharge volume determined by the design; Step E: Calculate the sewage volume in the catchment area based on multiple design parameters of the sewage pipe; Step F: According to the discharge volume of the sewage pipe, determine the implementation content of the sewage pipe so that it meets the design comprehensive sewage volume requirements of each catchment area; Step G: Verify through calculation that the implementation of the sewage pipe in the catchment area meets the sewage pipe discharge volume determined by the design; The steps BD and EF can be interchanged as a whole.

2. The design method of the rainwater and sewage separation drainage pipeline according to claim 1 is characterized in that: In step B, when designing the rainwater pipe, multiple design parameters of the rainwater pipe include the flow velocity of the rainwater pipe, the diameter and slope of the rainwater pipe, the rainwater design recurrence period P, the comprehensive runoff coefficient Ψ and the rainfall duration t, wherein, in the flow velocity of the rainwater pipe, the maximum flow velocity Vmax=5m / s, the flow velocity at full flow Vmin=0.75m / s, in the design parameters of the rainwater pipe diameter and slope, the minimum diameter of the connecting pipe between the rainwater inlet and the rainwater inspection well is not less than DN300, the slope i is not less than 0.01, the diameter of the rainwater pipe in other parts is not less than DN800, the slope i is not less than 0.003, the rainwater design recurrence period P is not less than 3 years, and the comprehensive runoff coefficient Ψ is not less than 0.

65.

3. The design method of the rainwater and sewage separation drainage pipeline according to claim 2 is characterized in that: The duration of rainfall t includes the ground water accumulation time t1 and the rainwater flow time t2 in the pipe, t=t1+t2. When determining the specific implementation content of the rainwater pipe in the step, t=, t=t1+2t2.

4. The design method of the rainwater and sewage separation drainage pipeline according to claim 1 is characterized in that: When designing and determining the drainage volume of the rainwater pipe in each catchment area in step B, the drainage volume of the rainwater pipe is selected according to the rainstorm intensity q, and the rainstorm intensity q is selected according to the rainstorm intensity formula Calculated; where q represents the intensity of heavy rain, P represents the recurrence period of heavy rain, the recurrence period of heavy rain is once in three years, t represents the duration of design rainfall, which is selected according to the length of the rainwater pipe network and the size of the catchment area, t=t1+ t2(min), t1 represents the ground water collection time, t2 represents the rainwater flow time in the pipe, t1 is 15min to 20min, and t2 is determined according to the flow velocity calculation.

5. The design method of the rainwater and sewage separation drainage pipeline according to claim 4 is characterized in that: In step E, the designed diameter of the rainwater pipe is DN300, and the rainwater pipe is spliced ​​by multiple rainwater pipe sections. Each rainwater pipe section adopts a grade II reinforced concrete pipe. Two adjacent pipe sections are connected by a socket and sealed with a rubber ring. A 180° gravel foundation is set at the bottom of the connection part of the rainwater pipe section, and the connection part is reinforced with 360° concrete full package. The slope of the rainwater pipe is not less than 1%.

6. The design method of the rainwater and sewage separation drainage pipeline according to any one of claim 1, characterized in that: In step E, the urban design comprehensive sewage volume calculation formula is used for calculation, and multiple design parameters of the sewage pipe are determined according to the drainage area, including the maximum daily water consumption index Qi[ m³ / (hm 2 .d)], different types of land use scale (hm 2 ), sewage discharge coefficient k1, daily water supply variation coefficient k2, groundwater infiltration rate k3, total sewage volume variation coefficient Kz, the urban design comprehensive sewage volume calculation formula is Q=∑k1×Qi× k2×k3×Ai / 24 / 3600×Kz.

7. The design method of the rainwater and sewage separation drainage pipeline according to claim 6 is characterized in that: In the step F, when determining the implementation content of the sewage pipe according to the drainage volume of the sewage pipe, it also includes calculating the sewage pipe flow rate according to the design slope of the sewage pipe, and adjusting the sewage flow rate to within the economic flow rate range, and then determining the pipe diameter according to the flow rate, and calculating the sewage discharge capacity of the sewage pipe by the sewage flow rate, the slope of the sewage pipe and the fullness, so that the designed sewage pipe meets the sewage pipe drainage volume requirements determined by the design.

8. The design method of rainwater and sewage separation drainage pipeline according to claim 7 is characterized in that: The sewage pipe flow rate is calculated using the following formula: ; In the formula, n is the roughness coefficient. The roughness coefficient of reinforced concrete pipes is n=0.013, and the roughness coefficient of plastic pipes is n=0.

011. When pipes of other materials are selected as sewage pipes, the roughness coefficient of rainwater pipes should be adjusted and selected.

9. The design method of the rainwater and sewage separation drainage pipeline according to any one of claims 1 to 8, characterized in that: The steps B to D specifically include the following steps: Step BD1: Design and arrange multiple groups of drainage pipe sections in multiple catchment areas, and obtain the spacing between two adjacent pipe sections in each group of pipe sections, and obtain the water collection time t1 based on the spacing, and at the same time determine the flow velocity v (m / s) in the rainwater pipe according to the design slope of the pipe section, and determine the water flow time t2 in the rainwater pipe based on the flow velocity calculation; Step BD2: Determine the catchment area F (ha) based on the distance between each pipe section and the service area of ​​the pipe section; Step BD3: Select and determine the comprehensive runoff coefficient Ψ, and thereby obtain the total runoff in the catchment area of ​​each pipe section; Step BD4: According to step BD1, the design flow of each pipe section in each rainwater pipe under the rainstorm intensity is calculated; Step BD5: Determine the diameter, slope and flow rate of each pipe section in the rainwater pipe, calculate the maximum water delivery capacity of each pipe section, and verify whether the maximum water delivery capacity of the pipeline meets the design flow requirements in step BD.

10. The method for designing a rainwater and sewage separation drainage pipeline according to any one of claims 1 to 8, characterized in that: The steps E to G specifically include the following steps: Step EG1: Design and arrange multiple groups of sewage pipe sections in multiple catchment areas, and determine the length and service area of ​​the pipes in each group of pipe sections; Step EG2: According to the specific flow rate q0 of each pipe section, the sewage flow rate q1 is calculated. When there is a ring pipe section, the transmission flow rate q2 is calculated at the same time, and the total average flow rate is calculated to obtain the sewage design flow rate Q1´ of each pipe section; Step EG3: Design and determine the slope, pipe material, and fullness of each pipe section, and calculate the sewage design flow Q1 of each pipe section separately according to the highest daily water consumption index qi of different types of land use, the scale of different types of land use ai, and the total variation coefficient Kz; Step EG4: Determine the pipe diameter D, slope I, flow velocity V and slope height of each pipe section in the sewage pipe, and calculate the pipe water delivery capacity of each pipe section; Step EG5: Verify and compare the sewage design flow Q1´ obtained in each pipe section of the sewage pipe based on the total variation coefficient Kz and the total average flow (L / s) with the sewage design flow Q1 of each pipe section obtained in step EG3, and verify that the pipeline water delivery capacity obtained in step EG4 meets Q1´ in step EG3 and Q1 in step EG4, thereby verifying that the sewage flow requirements are met.

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