Rural domestic sewage collection unit pipe network layout method based on GIS and dynamic programming algorithm

Abstract

The invention relates to a rural domestic sewage collection unit pipe network layout method based on a GIS (Geographic Information System) and a dynamic programming algorithm, which comprises the following steps of: firstly, collecting geographical, terrain and residential data through a GIS system, and processing and analyzing the geographical, terrain and residential data to obtain information such as domestic sewage generation amount, domestic sewage collection point distribution and terrain conditions; and then carrying out preliminary layout design of the pipe network by utilizing the information. And then a dynamic programming algorithm is used for pipe network optimization to find out a pipeline route and a connection mode with the minimum project investment and operation cost. And then adjusting and optimizing the pipelines of the preliminary layout according to an optimization result. And finally, performing technical and economic evaluation on the optimized pipe network layout. The method provided by the invention can realize efficient collection and treatment of rural domestic sewage on the premise of relatively low engineering investment, operation cost and maintenance cost, and has very high practical value.

Description

Technical Field

[0001] The invention belongs to the field of pipe network layout, and more specifically relates to a method for laying out a pipe network of rural domestic sewage collection units based on GIS and a dynamic programming algorithm. Background Art

[0002] The treatment and collection of domestic sewage in rural areas has always been an important difficulty in rural environmental governance. Due to the dispersed geographical location of rural areas, relatively low population density, and high construction and maintenance costs of domestic sewage facilities, it is difficult to solve the problem of domestic sewage treatment and collection in rural areas. At present, domestic sewage treatment facilities implemented on a household basis in some rural areas, such as septic tanks, have begun to show results, but due to the lack of unified planning and management, as well as the lack of technical means, this method still has many problems. Such as the difficulty in maintaining treatment equipment, low treatment efficiency, and how to dispose of treated domestic sewage. In addition, the current rural domestic sewage treatment methods are mainly based on traditional septic tanks and biogas tanks. Due to their low treatment efficiency, the residues after treatment are difficult to dispose of, which has led to the aggravation of rural environmental pollution problems.

[0003] Because of this, how to efficiently, economically and scientifically collect and treat domestic sewage in rural areas, so that it can be harmless and used as a resource without affecting the rural living environment, has become an urgent problem to be solved. In this regard, relevant experts and scholars have conducted a lot of research and proposed many equipment and technologies for collecting and treating domestic sewage. However, most of these equipment and technologies consider how to better collect and treat domestic sewage from the perspective of domestic sewage treatment, but pay less attention to how to more effectively collect domestic sewage so that it can be smoothly transported to the designated treatment site for treatment.

[0004] Therefore, how to combine the latest GIS technology with dynamic programming algorithms to develop a scientific and reasonable domestic sewage collection and transportation pipeline layout plan based on the characteristics of rural areas is of great theoretical and practical significance for improving the rural environment and protecting the health of rural residents.

[0005] At present, most of the existing research results on domestic sewage collection and treatment focus on the improvement and optimization of domestic sewage treatment technology, but there are few in-depth studies on the layout of domestic sewage collection unit pipe networks. In addition, even if some results propose the design and layout of domestic sewage collection pipe networks, most of them are qualitative analysis and description, and there are few quantitative calculations and optimization processes. This leads to the inability of these research results to achieve the expected results in practical applications. Summary of the invention

[0006] The technical problem to be solved by the present invention is mainly how to combine GIS technology and dynamic programming algorithm to scientifically and effectively plan and design the layout of rural domestic sewage collection pipe network to achieve efficient collection and treatment of rural domestic sewage, thereby reducing pollution and improving rural environmental quality.

[0007] In order to achieve the above object, the present invention is implemented by adopting the following technical scheme: the method comprises:

[0008] Data collection and processing: First, the geographical, topographical, and residential data of the rural area were collected through the GIS system, and processed and analyzed to obtain basic information on the amount of domestic sewage generated, the distribution of domestic sewage collection points, and terrain conditions;

[0009] Preliminary layout design of pipe network: Based on the collected data, the spatial analysis function of GIS system is applied to carry out preliminary layout design of pipe network for rural domestic sewage collection units, including determining the starting and ending points of the pipe network, as well as the rough direction of the pipes;

[0010] Dynamic programming algorithm optimization: The initially laid-out pipeline network is regarded as a network optimization problem and solved using a dynamic programming algorithm to find the pipeline route and connection method with the lowest engineering investment and operating costs.

[0011] Layout optimization and adjustment: Based on the optimization results of the dynamic programming algorithm, the initially laid out pipeline network is optimized and adjusted, the directions of some pipelines are changed, and the specifications and dimensions of some pipelines are adjusted to minimize engineering and operating costs.

[0012] Layout result evaluation: Finally, the optimized and adjusted pipeline network layout is evaluated to verify its economic and technical feasibility.

[0013] In one embodiment, the data collection and processing includes:

[0014] Data collection: Use GIS system to collect various geographic information including land use, geographical location, topography, landform, climate, water source location, building distribution, transportation routes, as well as population distribution, living habits, and animal husbandry distribution information;

[0015] Data preprocessing: Preprocessing methods include data cleaning, data integration, data transformation and data reduction;

[0016] Data analysis: Estimate the amount of domestic sewage generated through residential data and living habits data; determine possible domestic sewage collection points through building distribution and traffic route data; understand the laying conditions of underground pipelines through terrain, landforms and water source location data;

[0017] Data visualization: The key information after analysis is visualized, and the distribution and terrain conditions of domestic sewage collection points are shown on a map, which has great reference value for the subsequent pipe network layout design.

[0018] In one scheme, the preliminary layout design of the pipeline network is:

[0019] Determine the starting point and end point of the pipe network: the starting point of the pipe network is generally located at the location of the domestic sewage treatment facility, and the end point is located at the domestic sewage collection point. The domestic sewage collection points are distributed in residential areas and breeding grounds where domestic sewage is generated;

[0020] Use the path analysis function of GIS to determine the rough pipeline route: Through cost distance analysis, the optimal path from the starting point to each end point is obtained, that is, the rough pipeline direction;

[0021] Consider terrain and artificial geographical factors to modify the pipeline route: The laying of the pipeline takes terrain and artificial geographical factors into consideration and modifies the initial pipeline path;

[0022] Calculate and set pipeline parameters: For each pipeline, its length, slope, and pipe diameter parameters need to be calculated.

[0023] In one embodiment, the dynamic programming algorithm optimization includes:

[0024] The detailed implementation process is as follows:

[0025] Define state variables: All possible pipeline connection methods are considered as a directed graph, where each node represents a domestic sewage collection point, each edge represents a pipeline connection scheme, and the edge weight is set to the total cost of the connection scheme, including engineering investment and expected operating costs;

[0026] Set the initial state and final state: Assume that there are n domestic sewage collection points in the designated pipe network area, then the domestic sewage treatment facility can be naturally regarded as the starting point, represented as 0, and all domestic sewage collection points can be regarded as the end point, represented as 1, 2, ..., n in sequence;

[0027] State transfer equation: Let f(i) represent the minimum total cost from the domestic sewage treatment facility to the i-th collection point, then the state transfer equation is expressed as: f(i) = min(f(j) + cost(j,i)), where j represents all other collection points connected to the i-th collection point, and cost(j,i) represents the cost from the j-th collection point to the i-th collection point;

[0028] Through the dynamic programming algorithm, starting from the starting point, the minimum total cost to reach each collection point is calculated in turn, and the cost when reaching the end point is the optimal solution;

[0029] Backtrack to find the optimal path: Based on the minimum total cost solved by the dynamic programming algorithm, search backward from the end point to obtain the optimal pipeline connection method.

[0030] In one embodiment, the layout optimization and adjustment includes:

[0031] The detailed implementation process includes the following steps:

[0032] Adjust pipeline direction: according to the analysis results, adjust the pipeline direction that needs to be adjusted in the preliminary layout;

[0033] Optimize pipe specifications and sizes: The selection of pipe diameter needs to take flow and pressure factors into consideration. The appropriate pipe diameter can ensure the operating efficiency of the system and reduce maintenance costs.

[0034] Repeat the optimization process: Layout optimization and adjustment is an iterative process, which requires repeating the above steps until satisfactory results are achieved.

[0035] In one embodiment, the layout result evaluation includes:

[0036] Technical feasibility assessment: mainly includes the safety, reliability and efficiency of the pipeline network;

[0037] Economic evaluation: mainly includes construction cost and operation and maintenance cost considerations; the formula is as follows:

[0038] Total investment cost = construction cost + operation and maintenance cost

[0039] Among them, construction costs generally include pipe costs, labor costs, and equipment costs; operation and maintenance costs include energy costs, maintenance costs, and equipment replacement costs;

[0040] Comprehensive evaluation: The evaluation results of technical feasibility and economic efficiency are integrated to determine whether the pipeline network layout plan is optimal.

[0041] In one embodiment, the optimized pipe specifications and sizes include:

[0042] Calculation of sewage pipe flow;

[0043] (1) Specific flow rate: b-domestic sewage quota of residential area (L / (person.day)); p-population density (person / h㎡);

[0044] (2) Identify the amount of domestic sewage and concentrated flow in residential areas;

[0045] (3) Identify whether this section is transfer traffic;

[0046] (2) The average flow rate of this section is q1 = q0F

[0047] (3) Total average flow q = q 1+ q2

[0048] (4) Total coefficient of variation: calculated by interpolation;

[0049] (5) Design flow rate of domestic sewage Q1 = qK z ;

[0050] (6) Design flow rate of sewage in the pipe section Q = Q1 + Q2 + Q3.

[0051] In one embodiment, the optimized pipeline specifications and sizes include:

[0052] Hydraulic calculation of sewage pipes:

[0053] Assuming a pipe diameter and a filling degree that meets the maximum filling degree requirement, the pipe slope is determined based on the minimum slope and the ground slope;

[0054] 1) Design flow rate

[0055] 2) Water flow cross-sectional area: A

[0056]

[0057] 3) Hydraulic radius: R

[0058]

[0059] 4) Actual flow: Q = AV

[0060] Elevation calculation pipeline connection: if the pipe diameter increases, the pipe top will be connected flatly; if the pipe diameter remains unchanged, the water surface will be connected flatly; 1) Ground slope

[0061] 2) The bottom elevation of the pipe at the beginning of the pipe section is h3 = h1-H

[0062] 3) The bottom elevation of the pipe at the end of the pipe segment h4 = h3-IL

[0063] 4) Water level at the beginning of the pipe section h5 = h3 + h

[0064] 5) Water level at the end of the pipe section h6 = h4 + h

[0065] 6) The elevation of the top of the pipe at the beginning of the pipe section is h7 = h3 + D

[0066] 7) The elevation of the top of the pipe at the end of the pipe section is h8 = h4 + D

[0067] 8) Pipe section starting end burial depth H1 = h1-h3

[0068] 9) Pipe segment terminal burial depth H2 = h2-h4

[0069] Where b is population density (person / hm2) 2 )

[0070] p——domestic sewage quota in residential areas (L / (person·d))

[0071] F——Drainage area served by this pipe section (hm 2 )

[0072] q2——Average flow rate of this section (L / s)

[0073] Q2——Design flow rate of centralized sewage in this section (L / s)

[0074] Q3——Design flow rate of concentrated sewage transferred in this section (L / s)

[0075] n——tube wall roughness coefficient

[0076] D——pipe diameter (m)

[0077] L——Length of pipe section (m)

[0078] IL——Drop distance from the beginning to the end of the pipe section (m)

[0079] h——water depth (h / D×D) (m)

[0080] h1——ground elevation of the pipe section start point (m)

[0081] h2——ground elevation of pipe segment terminal (m)

[0082] Constraints

[0083] In the process of hydraulic calculation of sewage pipes, the constraints involved can be summarized as follows:

[0084] (1) Pipe diameter D

[0085] The constraints of pipe diameter on the hydraulic calculation of sewage pipes are reflected in two aspects. One is the minimum pipe diameter (i.e. the lower limit of the optional pipe diameter);

[0086] (2) Flow rate Q

[0087] When the design flow rate of a pipe section is less than the minimum flow rate of a certain pipe diameter, only a smaller pipe diameter can be selected. However, when the design flow rate of a pipe section is less than 12.5L / s, the pipe diameter can only be 200mm;

[0088] (3) Fullness h / D

[0089] The minimum filling degree of various pipe diameters is recommended to be no less than 0.25. Taking the maximum and minimum filling degrees as constraints, the design filling degree is selected to best determine the pipe diameter and achieve the purpose of optimization.

[0090] Beneficial effects of the present invention:

[0091] The beneficial effects of the present invention are mainly manifested in the following aspects:

[0092] 1) By combining the data collection and spatial analysis functions of the GIS system and the optimization and solving capabilities of the dynamic programming algorithm, the present invention can scientifically and effectively plan and design the layout of the rural domestic sewage collection network and improve the collection efficiency of domestic sewage.

[0093] 2) During the design process, the present invention comprehensively considers factors such as the amount of domestic sewage generated, the distribution of domestic sewage collection points, and topography, thereby ensuring the scientificity and practicality of the pipe network layout.

[0094] 3) By optimizing the layout of rural domestic sewage collection pipelines, domestic sewage can be effectively collected and treated, reducing environmental pollution, which is beneficial to the protection and improvement of the rural environment.

[0095] 4) The implementation of the present invention can not only improve the efficiency of domestic sewage treatment and improve the rural environment, but also reduce treatment costs, improve economic benefits, and bring significant social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 Flow chart for realizing the method of the present invention;

[0097] Figure 2 It is a flow chart of the optimization of the dynamic programming algorithm of the present invention;

[0098] Figure 3 The design flow calculation of the sewage main pipe in one embodiment of the present invention. DETAILED DESCRIPTION

[0099] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Typical embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in the present invention. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0100] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0101] like Figure 1 As shown, the rural domestic sewage collection unit pipe network layout method based on GIS and dynamic programming algorithm includes:

[0102] S1. Data collection and processing: First, the geographical, topographical, and residential data of rural areas are collected through the GIS system, and they are processed and analyzed to obtain basic information on the amount of domestic sewage generated, the distribution of domestic sewage collection points, and terrain conditions.

[0103] It mainly uses the capabilities of GIS systems to collect a variety of geographic information including land use, geographical location, topography, landforms, climate, water source location, building distribution, traffic routes, and other socio-economic information, as well as population distribution, living habits, animal husbandry distribution, etc. This information mainly comes from government public data or is obtained through field surveys, remote sensing, and other means.

[0104] The collected data is often irregular and may contain missing values, outliers, noise and other problems, which require preprocessing. Preprocessing methods include data cleaning, data integration, data transformation and data reduction.

[0105] Analyze the processed data to obtain key information. For example, through residential data and living habits data, the amount of domestic sewage generated can be estimated; through building distribution and traffic route data, possible domestic sewage collection points can be determined; through terrain, landform and water source location data, the laying conditions of underground pipelines can be understood.

[0106] Visualize the key information after analysis, for example, use a map to show the distribution of domestic sewage collection points, terrain conditions, etc., which is of great reference value for the subsequent pipe network layout design. Store all collected and processed data in a database or file for later use.

[0107] S2. Preliminary layout design of the pipe network: Based on the collected data, the spatial analysis function of the GIS system is applied to carry out the preliminary layout design of the pipe network for rural domestic sewage collection units, including determining the starting and ending points of the pipe network, as well as the rough direction of the pipes.

[0108] The preliminary layout design of the pipeline network mainly relies on the survey data and the spatial analysis function of the GIS system. The specific implementation steps are as follows:

[0109] Determine the starting and ending points of the pipe network: The starting point of the pipe network is generally located at the location of the domestic sewage treatment facility, and the end point is located at the domestic sewage collection point. The site selection of domestic sewage treatment facilities usually needs to consider factors such as terrain, flood line, groundwater level, traffic conditions, and construction costs. Domestic sewage collection points are usually distributed in residential areas, farms, and other places where domestic sewage is generated.

[0110] Use the path analysis function of GIS to determine the rough pipeline route: In the GIS system, the cost distance analysis or shortest path analysis function can be used to obtain the optimal path from the starting point to each end point, that is, the rough pipeline direction.

[0111] Correct the pipeline route by considering terrain and artificial geographical factors: The laying of pipelines needs to consider terrain factors (such as gullies, slopes, etc.) and artificial geographical factors (such as buildings, roads, etc.), and it may be necessary to make certain corrections to the initial pipeline path.

[0112] Calculate and set pipeline parameters: For each pipeline, you need to calculate its length, slope, diameter and other parameters. The specific calculation method needs to consider the actual engineering needs and local regulatory requirements.

[0113] S3. Dynamic programming algorithm optimization: The initially laid-out pipeline network is regarded as a network optimization problem and solved using a dynamic programming algorithm to find the pipeline route and connection method with the lowest engineering investment and operating costs.

[0114] The optimization problem of rural domestic sewage collection network layout usually includes two parts: engineering investment and operating costs. Engineering investment mainly includes the construction cost of the network, while operating costs mainly refer to the maintenance and operation costs of the network. Dynamic programming can find an optimal solution that can reduce both engineering investment and operating costs.

[0115] like Figure 2 The detailed implementation process is as follows:

[0116] S301. Define state variables: The key point of dynamic programming is to define appropriate state variables. In this problem, all possible pipeline connection methods can be regarded as a directed graph, where each node represents a domestic sewage collection point, each edge represents a pipeline connection scheme, and the weight of the edge can be set to the total cost of the connection scheme, including engineering investment and expected operating costs.

[0117] S302. Set the initial state and final state: Assuming that there are n domestic sewage collection points in the designated pipe network area, the domestic sewage treatment facility can be naturally regarded as the starting point, represented as 0, and all domestic sewage collection points can be regarded as the end points, represented as 1, 2, ..., n in sequence.

[0118] S303, state transfer equation: Let f(i) represent the minimum total cost from the domestic sewage treatment facility to the i-th collection point, then the state transfer equation can be expressed as: f(i) = min{f(j) + cost(j,i)}, where f(i) represents the minimum total cost from the starting point (domestic sewage treatment facility) to the collection point i; j is all the collection points connected to i; cost(j,i) represents the cost from collection point j to collection point i, including engineering investment and operating costs. The meaning of this formula is: the minimum total cost to reach collection point i is equal to the minimum value of the sum of the minimum total cost to reach collection point j and the cost from j to i.

[0119] S304, solution: starting from the starting point, calculate the minimum total cost to reach each collection point in turn through a dynamic programming algorithm, and the cost when finally reaching the end point is the optimal solution.

[0120] S305, backtracking to find the optimal path: Based on the minimum total cost solved by the dynamic programming algorithm, searching backward from the end point can find the optimal pipeline connection method. The main purpose is to find the path corresponding to the minimum total cost, that is, to find which j makes f(i) obtain the minimum value, mainly based on the calculated f(i) and cost(j,i) for judgment and selection.

[0121] S4. Layout optimization and adjustment: Based on the optimization results of the dynamic programming algorithm, the initially laid out pipeline network is optimized and adjusted, the directions of some pipelines are changed, and the specifications and dimensions of some pipelines are adjusted to minimize engineering and operating costs.

[0122] The detailed implementation process includes the following steps:

[0123] S401. Adjust the pipeline direction: According to the analysis results, adjust the pipeline direction that needs to be adjusted in the preliminary layout. The adjustment of pipeline direction often needs to be combined with factors such as topography, existing facilities, and planned roads, and a comprehensive balance is made to minimize engineering and operating costs.

[0124] S402. Optimize pipe specifications and sizes: The selection of pipe diameter needs to take flow and pressure factors into consideration. A suitable pipe diameter can ensure the operating efficiency of the system and reduce maintenance costs.

[0125] The optimized pipe specifications and sizes include:

[0126] Calculation of sewage pipe flow;

[0127] (1) Specific flow rate: b-domestic sewage quota of residential area (L / (person.day)); p-population density (person / h㎡);

[0128] (2) Identify the amount of domestic sewage and concentrated flow in residential areas;

[0129] (3) Identify whether this section is transfer traffic;

[0130] (2) The average flow rate of this section is q1 = q0F

[0131] (3) Total average flow q = q 1+ q2

[0132] (4) Total coefficient of variation: calculated by interpolation;

[0133] (5) Design flow rate of domestic sewage Q1 = qK z ;

[0134] (6) Design flow rate of sewage in the pipe section Q = Q1 + Q2 + Q3.

[0135] like Figure 3 As shown, in one embodiment, the design flow rate of the sewage main is calculated as follows:

[0136] ① Pipe section 1-2: According to the division of blocks and sewage pipe main pipes and trunk pipes, pipe section 1-2 belongs to the trunk pipe, among which only the sewage from Factory A is directly discharged into pipe section 1-2. The design flow rate of industrial wastewater from Factory A belongs to the flow rate of this section in the concentrated flow rate, and does not belong to the sewage volume of the residential area. Therefore, the design flow rate of pipe section 1-2 is the design flow rate of industrial wastewater from Factory A, which is 25L / s.

[0137] ② Pipe section 8-9: According to the division of blocks and main and trunk pipes of sewage pipes, pipe section 8-9 belongs to the trunk pipe, in which the sewage of blocks 1 and 2 is transferred and discharged into pipe section 8-9 through branch pipes. Therefore, the flow rate q1 of the residential sewage volume of pipe section 8-9 is 0, and the transfer flow rate q2 is equal to the sum of the areas of blocks 1 and 2 multiplied by the specific flow rate q0, that is, q2 = (1.21 + 1.70) × 0.486 = 1.41 L / s. The total average flow rate q = q1 + q2 = 1.41 L / s, and the total variation coefficient K z According to the table of total variation coefficient of domestic sewage, since the total average flow rate q = 1.41 < 5L / s, the total variation coefficient K z Take 2.7, the design flow rate of domestic sewage Q1=qK z =1.41×2.7=3.807L / s. There is no concentrated flow in pipe section 8-9, so the design flow of pipe section 8-9 is the design flow of domestic sewage Q1 in the domestic sewage volume of the residential area plus the flow of this section and the transfer flow of the concentrated flow, that is, the design flow = 3.807+0+0 = 3.807L / s.

[0138] ③ Pipe section 9-10: According to the division of blocks and main and trunk pipes of sewage pipes, pipe section 9-10 belongs to the trunk pipe, among which the sewage of blocks 1, 2, 7 and 8 is transferred and discharged into pipe section 9-10 through branch pipes. Therefore, the flow rate q1 of the residential sewage volume of pipe section 9-10 is 0, and the transfer flow rate q2 is equal to the sum of the areas of blocks 1, 2, 7 and 8 multiplied by the specific flow rate q0, that is, q2 = (1.21 + 1.70 + 1.43 + 2.21) × 0.486 = 3.18 L / s. The total average flow rate q = q1 + q2 = 3.18 L / s, and the total variation coefficient K z According to the table of total variation coefficient of domestic sewage volume, since the total average flow rate q = 3.18 < 5L / s, the total variation coefficient K z Take 2.7, the design flow rate of domestic sewage Q1=qK z=3.18×2.7=8.586L / s. There is no concentrated flow in pipe section 9-10, so the design flow of pipe section 9-10 is the design flow of domestic sewage Q1 in the domestic sewage volume of the residential area plus the flow of this section and the transfer flow of the concentrated flow, that is, the design flow = 8.586+0+0 = 8.586L / s.

[0139] ④10~2 pipe section: According to the division of blocks and sewage pipe main pipes and trunk pipes, 10~2 pipe section belongs to the trunk pipe, among which the sewage from blocks 1, 2, 7, 8, 13 and 14 is transferred and discharged into 10~2 pipe section through branch pipes. Therefore, the flow rate q1 of the residential sewage volume in 10~2 pipe section is 0, and the transfer flow rate q2 is equal to the sum of the areas of blocks 1, 2, 7, 8, 13 and 14 multiplied by the specific flow rate q0, that is, q2=(1.21+1.70+1.43+2.21+1.21+2.28)×0.486=4.88L / s. The total average flow rate q=q1+q2=4.88L / s, and the total variation coefficient K z According to the table of total variation coefficient of domestic sewage, since the total average flow rate q = 4.88 < 5L / s, the total variation coefficient K z Take 2.7, the design flow rate of domestic sewage Q1=qK z =4.88×2.7=13.176L / s. There is no concentrated flow in the pipe section 10-2, so the design flow of the pipe section 10-2 is the design flow of domestic sewage Q1 in the domestic sewage volume of the residential area plus the flow of this section and the transfer flow of the concentrated flow, that is, the design flow = 13.176+0+0 = 13.176L / s.

[0140] ⑤ Pipe section 2-3: According to the division of blocks and main and trunk pipes of sewage pipes, pipe section 2-3 belongs to the trunk pipe, among which the sewage of block 24 is directly discharged into pipe section 2-3, which belongs to the flow rate q1 of this section in the domestic sewage volume of the residential area. The flow rate q1 of this section is equal to the area of ​​block 24 multiplied by the specific flow rate q0, that is, q1 = 2.20 × 0.486 = 1.07L / s; the transfer flow rate q2 is equal to the total average flow rate of pipe section 10-2, that is, q2 = 4.88L / s. The total average flow rate of pipe section 2-3 q = q1 + q2 = 5.95L / s, the total variation coefficient K z According to the table of total variation coefficient of domestic sewage, since the total average flow rate q=5<5.95<15L / s, the total variation coefficient K z Between 2.4 and 2.7, K can be obtained by interpolation. z =2.67, domestic sewage design flow rate Q1 = qK z=5.95×2.67=15.887L / s. Pipe section 2~3 has a concentrated flow transferred from pipe section 1~2, i.e. 25L / s. Therefore, the design flow of pipe section 2~3 is the design flow of domestic sewage Q1 in the domestic sewage volume of the residential area plus the flow of this section of the concentrated flow and the transfer flow transferred from pipe section 1~2, i.e., the design flow = 15.887+0+25 = 40.887L / s.

[0141] ⑥ Pipe section 3-4: According to the division of blocks and main and trunk pipes of sewage pipes, pipe section 3-4 belongs to the trunk pipe. The sewage of block 25 is directly discharged into pipe section 3-4, which belongs to the flow rate q1 of this section in the domestic sewage volume of the residential area. The flow rate q1 of this section is equal to the area of ​​block 25 multiplied by the specific flow rate q0, that is, q1 = 1.38 × 0.486 = 0.67L / s; the transfer flow rate q2 is equal to the total average flow rate of pipe sections 3-4, that is, q2 = 5.95L / s. The total average flow rate of pipe sections 3-4 q = q1 + q2 = 6.62L / s, the total variation coefficient K z According to the table of total variation coefficient of domestic sewage, since the total average flow rate q=5<6.62<15L / s, the total variation coefficient K z Between 2.4 and 2.7, K can be obtained by interpolation. z =2.65, domestic sewage design flow rate Q1 = qK z =6.62×2.65=17.543L / s. Pipe section 3-4 has a concentrated flow transferred from pipe section 1-2, i.e. 25L / s. Therefore, the design flow of pipe section 3-4 is the design flow of domestic sewage Q1 in the domestic sewage volume of the residential area plus the flow of this section of the concentrated flow and the transfer flow transferred from pipe section 1-2, i.e., the design flow = 17.543+0+25 = 42.543L / s.

[0142] ⑦ Calculation table of design flow rate of sewage main pipe

[0143]

[0144]

[0145] The optimized pipeline specifications and sizes mentioned above include:

[0146] Hydraulic calculation of sewage pipes:

[0147] Assuming a pipe diameter and a filling degree that meets the maximum filling degree requirement, the pipe slope is determined based on the minimum slope and the ground slope;

[0148] 1) Design flow rate

[0149] 2) Water flow cross-sectional area: A

[0150]

[0151] 3) Hydraulic radius: R

[0152]

[0153] 4) Actual flow: Q = AV

[0154] Elevation calculation pipeline connection: if the pipe diameter increases, the pipe top will be connected flatly; if the pipe diameter remains unchanged, the water surface will be connected flatly; 1) Ground slope

[0155] 2) The bottom elevation of the pipe at the beginning of the pipe section is h3 = h1-H

[0156] 3) The bottom elevation of the pipe at the end of the pipe segment h4 = h3-IL

[0157] 4) Water level at the beginning of the pipe section h5 = h3 + h

[0158] 5) Water level at the end of the pipe section h6 = h4 + h

[0159] 6) The elevation of the top of the pipe at the beginning of the pipe section is h7 = h3 + D

[0160] 7) The elevation of the top of the pipe at the end of the pipe section is h8 = h4 + D

[0161] 8) Pipe section starting end burial depth H1 = h1-h3

[0162] 9) Pipe segment terminal burial depth H2 = h2-h4

[0163] Where b is population density (person / hm2) 2 )

[0164] p——domestic sewage quota in residential areas (L / (person·d))

[0165] F——Drainage area served by this pipe section (hm 2 )

[0166] q2——Average flow rate of this section (L / s)

[0167] Q2——Design flow rate of centralized sewage in this section (L / s)

[0168] Q3——Design flow rate of concentrated sewage transferred in this section (L / s)

[0169] n——tube wall roughness coefficient

[0170] D——pipe diameter (m)

[0171] L——Length of pipe section (m)

[0172] IL——Drop distance from the beginning to the end of the pipe section (m)

[0173] h——water depth (h / D×D) (m)

[0174] h1——ground elevation of the pipe section start point (m)

[0175] h2——ground elevation of pipe segment terminal (m)

[0176] Constraints

[0177] In the process of hydraulic calculation of sewage pipes, the constraints involved can be summarized as follows:

[0178] (1) Pipe diameter D

[0179] The constraints of pipe diameter on the hydraulic calculation of sewage pipes are reflected in two aspects. One is the minimum pipe diameter (i.e. the lower limit of the optional pipe diameter);

[0180] (2) Flow rate Q

[0181] When the design flow rate of a pipe section is less than the minimum flow rate of a certain pipe diameter, only a smaller pipe diameter can be selected. However, when the design flow rate of a pipe section is less than 12.5L / s, the pipe diameter can only be 200mm;

[0182] (3) Fullness h / D

[0183] The minimum filling degree of various pipe diameters is recommended to be no less than 0.25. Taking the maximum and minimum filling degrees as constraints, the design filling degree is selected to best determine the pipe diameter and achieve the purpose of optimization.

[0184] Hydraulic calculation of sewage trunk pipe:

[0185] ① Pipe section 1-2: Input the pipe section number, pipe length L=110m, design flow Q=25.00L / s, ground elevation of the start end 86.20m and the end end 86.10m into the hydraulic calculation table. The ground slope can be obtained from the ground elevation of the start end and the end end and the pipe length. It is known that the buried depth of the starting end of the pipeline is 2m (to meet the requirement of minimum cover thickness of at least 0.7m), and the elevation of the inner bottom of the pipe at the starting end of the pipe section = the starting ground elevation - the buried depth, so the elevation of the inner bottom of the pipe at the starting end of the pipe section 1 to 2 is 86.20-2=84.20m. Afterwards, a trial calculation was performed, and the minimum design pipe diameter D was input as 300mm (generally, the starting and breaking pipelines are designed according to the minimum pipe diameter, and the minimum pipe diameter is 300mm). According to the maximum filling degree h / D corresponding to the 300mm pipe diameter of 0.55 and the minimum design slope I of 0.003, I=0.003 was input (the ground slope is less than the minimum slope, and the pipeline slope takes the minimum slope. Only the minimum slope of the minimum pipe diameter of 300mm is specified, and the remaining pipes larger than the minimum pipe diameter only need the flow rate to be greater than the minimum flow rate of 0.6m / s). Under the premise of h / D≤0.55, the maximum filling degree h / D was continuously changed so that the value of the actual flow rate Q was slightly larger than the value of the design flow rate. After continuous attempts, it was obtained that when D=300, h / D=0.49, h=0.15, and I=0.003, the actual flow rate Q=Av=25.59L / s was slightly larger than the design flow rate Q=25.00L / s (slightly larger than but not exceeding 1L / s). According to the formula, the design flow rate can be obtained Greater than the minimum design flow rate of 0.6m / s meets the requirements; according to the water flow cross-sectional area formula It can be obtained that A = 0.034 m2; according to the hydraulic radius formula It can be obtained that R = 0.07m; according to the slope formula IL = 0.003 × 110 = 0.33m; the bottom elevation of the pipe at the end of the pipe section = the bottom elevation of the pipe at the beginning of the pipe section - slope = 84.20-0.33 = 83.87m; the buried depth of the pipe section terminal = the ground terminal elevation - the bottom elevation of the pipe at the beginning of the pipe section = 86.10-83.87 = 2.23m; the water surface elevation of the beginning of the pipe section = the bottom elevation of the pipe at the beginning of the pipe section + water depth

[0186] h=84.20+0.15=84.35m;The bottom elevation of the pipe at the end of the pipe section=the water surface elevation at the beginning of the pipe section-the slope=84.35-0.33=84.02m. So far, the hydraulic calculation of pipe sections 1 to 2 has been completed.

[0187] ②2-3 pipe sections: Enter the pipe section number, pipe length L = 250m, design flow Q = 40.89L / s, ground elevation of the start end 86.10m and the end end 86.05m into the hydraulic calculation table. The ground slope can be obtained from the ground elevation of the start end and the end end and the pipe length. Since the design flow rate Q = 40.89L / s of the pipeline is much larger than the design flow rate of sections 1 to 2, the design pipe diameter D is taken as 350mm (the flow rate gradually increases, and the pipe diameter generally increases or remains unchanged) during the trial calculation. According to the maximum filling degree h / D corresponding to the 350mm pipe diameter of 0.65, under the premise of h / D ≤ 0.55, the maximum filling degree h / D and the slope I are continuously changed (in principle, when the ground slope is small, the pipeline slope is as small as possible and the filling degree is as large as possible), so that the actual flow rate Q is slightly larger than the design flow rate. After continuous attempts, it is found that when D = 350, h / D = 0.55, h = 0.19, and I = 0.023, the actual flow rate Q = Av = 40.97L / s is slightly larger than the design flow rate Q = 40.89L / s. According to the formula, the design flow rate can be obtained Greater than the minimum design velocity of 0.6m / s meets the requirements (the velocity generally increases step by step); according to the water flow cross-sectional area formula It can be obtained that A = 0.054 m2; according to the hydraulic radius formula It can be obtained that R = 0.09m; according to the slope formula IL = 0.023 × 250 = 0.575m; because the pipe diameter increases from 300mm to 350mm, the pipe section is connected using the top flat connection, the inner bottom elevation of the pipe at the beginning of the pipe section = the inner bottom elevation of the pipe at the end of the 1-2 pipe section + the pipe diameter of the 1-2 pipe section - the pipe diameter of the 2-3 pipe section = 83.87 + 0.3 - 0.35 = 83.82m; the inner bottom elevation of the pipe at the end of the pipe section = the inner bottom elevation of the pipe at the beginning of the pipe section - slope = 83.82 - 0.575 = 83. 25m; buried depth at the beginning of the pipe segment = ground elevation at the beginning of the pipe segment - elevation of the inner bottom of the pipe at the beginning of the pipe segment = 86.10-83.82 = 2.28m; buried depth at the end of the pipe segment = ground elevation at the end of the pipe segment - elevation of the inner bottom of the pipe at the beginning of the pipe segment = 86.05-83.25 = 2.80m; water surface elevation at the beginning of the pipe segment = elevation of the inner bottom of the pipe at the beginning of the pipe segment + water depth h = 83.82+0.19 = 84.01m; water surface elevation at the end of the pipe segment = water surface elevation at the beginning of the pipe segment - slope drop = 84.01-0.575 = 83.44m. So far, the hydraulic calculations of pipe segments 1 to 2 have been completed.

[0188] ③3-4 pipe section: Enter the pipe section number, pipe length L = 170m, design flow Q = 42.54L / s, ground elevation of the start end 86.05m and the end end 86.00m into the hydraulic calculation table. The ground slope can be obtained from the ground elevation of the start end and the end end and the pipe length. Since the design flow rate Q = 42.54L / s of the pipeline is almost equal to the design flow rate of the 2-3 pipe sections, the design pipe diameter D is taken as 350mm during the trial calculation. According to the maximum filling degree h / D corresponding to the 350mm pipe diameter, which is 0.65, the maximum filling degree h / D and the slope I are continuously changed under the premise of h / D≤0.55, so that the actual flow rate Q is slightly larger than the design flow rate. After continuous attempts, it is found that when D = 350, h / D = 0.57, h = 0.20, and I = 0.023, the actual flow rate Q = Av = 43.39L / s is slightly larger than the design flow rate Q = 42.54L / s. According to the formula, the design flow rate can be obtained Greater than the minimum design flow rate of 0.6m / s meets the requirements; according to the water flow cross-sectional area formula We can get A = 0.057 m2; according to the hydraulic radius formula It can be obtained that R = 0.09m; according to the slope formula IL = 0.023 × 170 = 0.391m; since the pipe diameter is 350mm unchanged, the pipe section is connected using the water surface flat connection, the water surface elevation of the starting end of the pipe section = the water surface elevation of the terminal of the 2~3 pipe section = 83.44m; the water surface elevation of the terminal of the pipe section = the water surface elevation of the starting end of the pipe section - slope = 83.44-0.391 = 83.05m; the bottom elevation of the pipe at the starting end of the pipe section = the water surface elevation of the terminal of the 2~3 pipe section - 3~ The water depth of pipe section 4 is h = 83.44-0.20 = 83.24m; the inner bottom elevation of the pipe section terminal = the inner bottom elevation of the pipe section starting point - the slope = 83.24-0.391 = 82.85m; the buried depth of the pipe section starting point = the ground starting point elevation - the inner bottom elevation of the pipe section starting point = 86.05-83.24 = 2.81m; the buried depth of the pipe section terminal = the ground terminal elevation - the inner bottom elevation of the pipe section starting point = 86.00-82.85 = 3.15m. At this point, the hydraulic calculations of pipe sections 3 to 4 are all completed.

[0189] S403, repeat the optimization process: Layout optimization and adjustment is an iterative process, and the above steps need to be repeated until a satisfactory result is achieved.

[0190] S5. Layout result evaluation: Finally, the optimized and adjusted pipeline network layout is evaluated to verify its economic and technical feasibility.

[0191] Technical feasibility assessment: mainly includes the safety, reliability, efficiency and other considerations of the pipeline network. For example, it is necessary to verify whether the design of the pipeline network meets the relevant design and construction specifications, whether the flow meets the requirements, and check whether there are possible safety hazards.

[0192] Economic evaluation: mainly includes considerations such as engineering construction costs and operation and maintenance costs. It is necessary to calculate the estimated investment and operating costs of the optimized pipeline network layout plan to confirm its economic benefits. The formula is as follows:

[0193] Total investment cost = construction cost + operation and maintenance cost

[0194] Among them, engineering construction costs generally include pipe costs, labor costs, equipment costs, etc., and operation and maintenance costs generally include energy costs, maintenance costs, equipment replacement costs, etc.

[0195] Comprehensive evaluation: The evaluation results of technical feasibility and economic efficiency are combined to determine whether the pipeline network layout plan is optimal. If the evaluation results are not satisfactory, it is necessary to return to the optimization and adjustment stage to re-layout the pipeline network.

[0196] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM).

[0197] It should be understood that the detailed description of the technical solutions of the present invention by means of the preferred embodiments is illustrative rather than restrictive. A person skilled in the art may modify the technical solutions described in the embodiments, or replace some of the technical features by equivalents, based on reading the specification of the present invention; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the layout of rural domestic sewage collection unit pipe networks based on GIS and dynamic programming algorithm, characterized by: The method includes: Data collection and processing: Geographic, topographic, and residential data of rural areas are collected through the GIS system to obtain basic information on domestic sewage generation, distribution of domestic sewage collection points, and terrain conditions; Preliminary layout design of pipe network: Based on the collected data, the spatial analysis function of GIS system is applied to carry out preliminary layout design of pipe network for rural domestic sewage collection units, including determining the starting and ending points of the pipe network, as well as the rough direction of the pipes; Dynamic programming algorithm optimization: The initially laid-out pipeline network is regarded as a network optimization problem, and the dynamic programming algorithm is used to solve it to find the pipeline route and connection method with the lowest engineering investment and operating costs; Layout optimization and adjustment: According to the optimization results of the dynamic programming algorithm, the preliminary layout of the pipeline network is optimized and adjusted, the direction of some pipelines is changed, and the specifications and dimensions of the pipelines are adjusted; Layout result evaluation: Evaluate the optimized and adjusted pipeline network layout to verify its economic and technical feasibility.

2. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 1 is characterized by: The data collection and processing include: Data collection: Use GIS system to collect geographical information including land use, geographical location, topography, landform, climate, water source location, building distribution, transportation route, as well as population distribution, living habits, and animal husbandry distribution information; Data preprocessing: Preprocessing methods include data cleaning, data integration, data transformation and data reduction; Data analysis: estimate the amount of domestic sewage generated through residential data and living habits data; determine domestic sewage collection points through building distribution and traffic route data; and use terrain, landform and water source location data; Data visualization: The key information after analysis is visualized, and the distribution and terrain conditions of domestic sewage collection points are shown on a map.

3. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 1 is characterized by: The preliminary layout design of the pipeline network is as follows: Determine the starting point and end point of the pipe network: the starting point of the pipe network is located at the location of the domestic sewage treatment facility, and the end point is located at the domestic sewage collection point. The domestic sewage collection points are distributed in residential areas and breeding grounds where domestic sewage is generated; Use the path analysis function of GIS to determine the rough pipeline route: Through cost distance analysis, the optimal path from the starting point to each end point is obtained, which is the rough pipeline direction; Consider terrain and artificial geographical factors to modify the pipeline route: The laying of the pipeline takes terrain and artificial geographical factors into consideration and modifies the initial pipeline path; Calculate and set pipeline parameters: For each pipeline, its length, slope, and pipe diameter parameters need to be calculated.

4. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 1 is characterized by: The dynamic programming algorithm optimization includes: Define state variables: All pipeline connection methods are considered as a directed graph, where each node represents a domestic sewage collection point, each edge represents a pipeline connection scheme, and the edge weight is set to the total cost of the connection scheme, including engineering investment and expected operating costs; Set the initial state and final state: Assume that there are n domestic sewage collection points in the designated pipe network area, then take the domestic sewage treatment facility as the starting point, represented by 0, and take all domestic sewage collection points as the end points, represented by 1, 2, ..., n in sequence; State transfer equation: Let f(i) represent the minimum total cost from the domestic sewage treatment facility to the i-th collection point, then the state transfer equation is expressed as: f(i) = min(f(j) + cost(j,i)), where j represents all other collection points connected to the i-th collection point, and cost(j,i) represents the cost from the j-th collection point to the i-th collection point; Through the dynamic programming algorithm, starting from the starting point, the minimum total cost to reach each collection point is calculated in turn, and the cost when reaching the end point is the optimal solution; Backtrack to find the optimal path: Based on the minimum total cost solved by the dynamic programming algorithm, search backward from the end point to obtain the optimal pipeline connection method.

5. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 1 is characterized by: The layout optimization and adjustment include: Adjust pipeline direction: according to the analysis results, adjust the pipeline direction that needs to be adjusted in the preliminary layout; Optimize pipe specifications and sizes: The selection of pipe diameter takes into account flow and pressure factors. Appropriate pipe diameter ensures system operation efficiency and reduces maintenance costs. Repeat the optimization process: Layout optimization and adjustment is an iterative process, repeating the above steps until a satisfactory result is achieved.

6. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 1 is characterized by: The layout result evaluation includes: Technical feasibility assessment: including considerations of the safety, reliability and efficiency of the pipeline network; Economic evaluation: including construction cost and operation and maintenance cost considerations; the formula is as follows: Total investment cost = construction cost + operation and maintenance cost; Among them, the construction cost includes pipe costs, labor costs, and equipment costs; the operation and maintenance costs include energy costs, maintenance costs, and equipment replacement costs; Comprehensive evaluation: The evaluation results of technical feasibility and economic efficiency are integrated to determine whether the pipeline network layout plan is optimal.

7. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 5 is characterized by: The optimized pipe specifications and sizes include: Calculation of sewage pipe flow; (1) Specific flow rate: b-domestic sewage quota of residential area (L / (person.day)); p-population density (person / h㎡); (2) Identify the amount of domestic sewage and concentrated flow in residential areas; (3) Identify whether this section is transfer traffic; (2) The average flow rate of this section is q1 = q0F (3) Total average flow q = q 1+ q2 (4) Total coefficient of variation: calculated by interpolation; (5) Design flow rate of domestic sewage Q1 = qK z ; (6) Design flow rate of sewage in the pipe section Q = Q1 + Q2 + Q3.

8. The method for rural domestic sewage collection unit pipe network layout based on GIS and dynamic programming algorithm according to claim 5 is characterized by: The optimized pipeline specifications and sizes mentioned above include: Hydraulic calculation of sewage pipes: Assuming a pipe diameter and a filling degree that meets the maximum filling degree requirement, the pipe slope is determined based on the minimum slope and the ground slope; 1) Design flow rate 2) Water flow cross-sectional area: A 3) Hydraulic radius: R 4) Actual flow: Q = AV Elevation calculation: Pipeline connection: if the pipe diameter increases, the pipe top will be connected flatly; if the pipe diameter remains unchanged, the water surface will be connected flatly; 1) Ground slope 2) The bottom elevation of the pipe at the beginning of the pipe section is h3 = h1-H 3) The bottom elevation of the pipe at the end of the pipe segment h4 = h3-IL 4) Water level at the beginning of the pipe section h5 = h3 + h 5) Water level at the end of the pipe section h6 = h4 + h 6) The elevation of the top of the pipe at the beginning of the pipe section is h7 = h3 + D 7) The elevation of the top of the pipe at the end of the pipe section is h8 = h4 + D 8) Pipe section starting end burial depth H1 = h1-h3 9) Pipe segment terminal burial depth H2 = h2-h4 Where b is population density (person / hm2) 2 ) p——domestic sewage quota in residential areas (L / (person·d)) F——Drainage area served by this pipe section (hm 2 ) q2——Average flow rate of this section (L / s) Q2——Design flow rate of centralized sewage in this section (L / s) Q3——Design flow rate of concentrated sewage transferred in this section (L / s) n——pipe wall roughness coefficient D——pipe diameter (m) L——Length of pipe section (m) IL——Drop distance from the beginning to the end of the pipe section (m) h——water depth (h / D×D) (m) h1——ground elevation of the pipe section start point (m) h2——ground elevation of the pipe segment terminal (m) constraint conditions: In the process of hydraulic calculation of sewage pipes, the constraints involved are as follows: (1) Pipe diameter D The constraints of pipe diameter on the hydraulic calculation of sewage pipes are reflected in two aspects. One is the minimum pipe diameter, which is the lower limit of the optional pipe diameter; (2) Flow rate Q When the design flow rate of the pipe section is less than the minimum flow rate of a certain pipe diameter, select a smaller pipe diameter; but when the design flow rate of the pipe section is less than 12.5L / s, the pipe diameter is 200mm; (3) Fullness h / D The minimum filling degree of various pipe diameters is not less than 0.25; taking the maximum and minimum filling degrees as constraints, the design filling degree is selected to best determine the pipe diameter to achieve the purpose of optimization.

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