CN112036043B - Method for calculating fracture model of long-distance gravity flow large-pipe-diameter water supply pipeline - Google Patents
Method for calculating fracture model of long-distance gravity flow large-pipe-diameter water supply pipeline Download PDFInfo
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Abstract
The invention discloses a method for calculating a long-distance gravity flow large-pipe-diameter water supply pipeline rupture model, which comprises the following steps: s1: after the pipeline rupture accident occurs, calculating a model that the water inlet head is constant before the upstream water inlet gate is closed and the leakage is carried out at the rupture position under the constant water head; s2: calculating a model of continuous leakage of the residual water in the pipeline until the water is exhausted after the gate is closed; the problem of 'seamless' integration of GIS and professional model is solved, and meanwhile, the problem of on-demand expansion of GIS objects and analysis functions is solved.
Description
Technical Field
The invention relates to the field of calculation of a large-diameter water supply pipeline rupture model, in particular to a method for calculating a long-distance gravity flow large-diameter water supply pipeline rupture model.
Background
Although the burst accident inundation simulation calculation modes are various, the simulation calculation of any break point model is realized on the long-distance gravity flow large-pipe-diameter water supply pipeline in the cold region; the dual-object sharing structure framework for sharing the GIS object and the model object is realized, the GIS object provides GIS core functions such as space analysis and space information management for the model object, the model object provides core functions of professional model simulation analysis such as physical mechanism and space-time process for the GIS object, and the management and analysis of the space-time attribute information of the GIS object are realized. The GIS framework of the double-object sharing structure is constructed, the 'seamless' integration problem of the GIS and the professional model is solved, meanwhile, the on-demand expansion problem of GIS objects and analysis functions is solved, and the model calculation for solving any break point by the GIS of the multi-dimensional space-time structure is established for the first time.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for calculating a long-distance gravity flow large-diameter water supply pipeline rupture model, solves the problem of 'seamless' integration of GIS and a professional model, and simultaneously solves the problem of on-demand expansion of GIS objects and analysis functions.
The technical scheme adopted by the invention is that the method for calculating the long-distance gravity flow large-diameter water supply pipeline rupture model comprises the following steps:
s1: after the pipeline rupture accident occurs, calculating a model that the water inlet head is constant before the upstream water inlet gate is closed and the leakage is carried out at the rupture position under the constant water head;
s2: calculating a model of continuous leakage of the residual water in the pipeline until the water is exhausted after the gate is closed;
s3: the starting point of the long-distance water delivery line of the millstone mountain is arranged on the right side of the millstone mountain water reservoir, the distance from the starting point to the dam is 50.0m, the elevation of the central point at the inlet of the pipeline is 292.54m, the designed water intake level is 298.0m, the normal water storage level of the reservoir is 318.0m, the check flood level of the reservoir is 323.26m, and the water heads at the inlets of the pipeline obtained under the three water level conditions are 5.46m, 25.46m and 30.72m respectively;
s4: on the basis of S3, a rupture model of a pipeline is built by taking a rupture point as a center, and a seepage inundation model is built by comprehensively considering river channels, highways and civil house infrastructures;
S5: calculating and analyzing the open traffic of the flat area and the five-way city;
s6: a GIS frame of a double-object sharing structure for realizing the sharing of the GIS object and the model object;
s7: providing spatial analysis and spatial information management by GIS objects and models;
s8: the GIS object and the model provide a core function of simulation analysis of a physical mechanism and a space-time process professional model;
space-time attribute information management and analysis are provided by GIS objects and models, a GIS frame of a double-object sharing structure is constructed, and the problem of 'seamless' integration of GIS and professional models is solved;
s9: the GIS object and the model are used for solving the problem of on-demand expansion of the GIS object and the analysis function, and the GIS with the multidimensional space-time structure is created.
The method for calculating the long-distance gravity flow large-pipe-diameter water supply pipeline rupture model has the following beneficial effects:
1. in order to effectively solve the serious consequences of land inundation, casualties, traffic interruption, property loss and the like possibly caused by bursting of the millstone long-distance water conveying line, the practical construction of the millstone long-distance water conveying line is combined, and a millstone long-distance water conveying line bursting model, namely a pipe bursting model for short, is established by utilizing a two-dimensional shallow water flow principle around the risk assessment and normal-abnormal management targets. The model comprises two parts of pipeline rupture water flow overflow simulation and overflow inundation simulation, takes a long-distance water transmission line of approximately 177km along a DEM digital elevation as a support, and constructs a simulation system taking single-point bursting and multi-source influence as cores, and is used for predicting and evaluating inundation influence range and disaster degree caused by pipeline rupture.
2. The pipeline bursting overflow simulates the flow process before opening and closing and the flow process after opening, simulates the water flow overflow situation of the complete flow process of the break point in actual production, performs flooding simulation on selected points of intersection such as the most explosive point pipe pressure amplitude intense point, the overpressure point, the safety concern point city, the river channel, the highway and the like, such as the five-way city and the flat house area, and performs detailed calculation on the flooding area and the flooding depth generated after pipe bursting, thereby forming a pipe bursting simulation result library, obtaining better effect, and providing important reference basis for the starting decision of an emergency plan by the simulation analysis result.
Drawings
FIG. 1 is a flow chart of the line rupture model modeling of the present invention.
FIG. 2 is a schematic diagram of a surface computing unit discrete grid of the present invention.
FIG. 3 is a flow of model calculation of the present invention.
Fig. 4 is a view showing GIS processing of ground object information according to the present invention.
Fig. 5 is a view showing GIS processing of ground object information according to the present invention.
Fig. 6 is a schematic diagram of a two-dimensional differential mesh of the present invention.
FIG. 7 is a flow chart of the calculation of the outflow process before closing the flow regulating and pressure regulating valve.
FIG. 8 is a flow chart of the outflow process calculation after closing the flow regulating and pressure regulating valve.
Fig. 9 is a schematic view of the total and free water head along the path of the present invention.
FIG. 10 is a schematic diagram of the breaking points and simulation ranges of the horizontal house area of the present invention.
FIG. 11 is a graph of the calculated area building profile for a single-storey house according to the invention.
FIG. 12 is a graph of the calculated area building profile for a single-story building of the present invention.
FIG. 13 is a graph showing the process of the leakage flow rate of the breach in the horizontal house area according to the present invention.
FIG. 14 is a graph of a simulation of the flooding of a single-story zone breach (condition 1) of the present invention.
FIG. 15 is a graph of the process line changes for the single-story zone breach of the present invention (condition 1).
FIG. 16 is a graph of the one-storey house break leakage flow process (regime 2) of the present invention.
FIG. 17 is a graph of a simulation of the flooding of a single-story zone breach (condition 2) of the present invention.
FIG. 18 is a graph of the process line changes for the single-story zone breach of the present invention (condition 2).
FIG. 19 is a graph of the one-storey house break leakage flow process (regime 3) of the present invention.
FIG. 20 is a graph of a simulation of the flooding of a single-story zone breach (condition 3) of the present invention.
FIG. 21 is a graph of the process line changes for the single-story zone breach of the present invention (condition 3).
FIG. 22 is a schematic diagram of the five elements break points and simulation ranges of the present invention.
FIG. 23 is a calculated regional building distribution diagram for five general cities of the present invention.
FIG. 24 is a topographical view of the surrounding of the five elements break point of the present invention.
FIG. 25 is a topographical view around a five elements break point according to the present invention.
FIG. 26 is a simulation of the flooding of a five-element break (condition 1) according to the present invention.
FIG. 27 is a graph of the process line changes for the five elements break (condition 1) of the present invention.
FIG. 28 is a five-way city breach leakage flow process of the present invention (condition 2).
FIG. 29 is a simulation of the flooding of a five-element break (condition 2) according to the present invention.
FIG. 30 is a graph of the process line changes for the five elements break (condition 2) of the present invention.
FIG. 31 is a graph of the five elements breach leak flow process of the present invention (condition 3).
FIG. 32 is a simulation of the flooding of a five-element break (condition 3) according to the present invention.
FIG. 33 is a graph of the process line changes for the five elements break (condition 3) of the present invention.
Fig. 34 is a schematic view of the weak segment break point 1 and the simulation range of the present invention.
Fig. 35 is a calculated regional building profile for weak segment 1 of the present invention.
Fig. 36 is a topographical view around the weak segment break point 1 of the present invention.
Fig. 37 is a graph showing the leakage flow rate at the weak segment break point 1 according to the present invention.
FIG. 38 is a simulated flooding pattern for a weak segment breach 1 of the present invention.
Fig. 39 is a schematic diagram of the weak segment break point 2 and the simulation range of the present invention.
Fig. 40 is a calculated regional building profile for weak segment 2 of the present invention.
Fig. 41 is a topographical view of the vicinity of the weak segment break point 2 of the present invention.
Fig. 42 is a graph showing the leakage flow rate at the weak segment break point 2 according to the present invention.
FIG. 43 is a simulated flooding pattern for a weak segment breach 2 of the present invention.
FIG. 44 is a graph of average submerged depths versus three roughness rates for the present invention.
FIG. 45 is a graph of submerged area versus the three roughness ratios of the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.
The pipe explosion is the most serious accident for the long-distance water conveying line of millstone mountain. From risk impact analysis, it is known that once a pipe burst occurs, it can lead to interruption of the water supply and a range of flooding downstream. The water supply interruption can cause the water supply interruption in a large range in urban areas, so that the normal life of people is seriously influenced, if the water supply interruption is too long, the people can be dissatisfied and panicked, and the social stability is extremely adversely affected. Meanwhile, the surrounding area is submerged by the pipe explosion, and the surrounding ecological environment is damaged. The method is used for scientifically predicting and evaluating the influence and the result caused by the pipeline rupture, simulating the element change processes such as the submerged range, the submerged water depth and the like through the pipeline rupture submerged model, and providing important decision basis for starting the emergency plan, so that a series of problems caused by the pipeline rupture are effectively solved.
1. Overall working thinking
The full length of the first period of the water delivery pipeline of the millstone mountain water warehouse water supply project is 175.33km, the full length of the second period is 176.93km, the starting point is the millstone mountain water warehouse in the Harbin five-ordinary city, the millstone mountain water warehouse passes through the single-storey house area of the five-ordinary city, the A city, the double city and the Harbin city along the way, and the end point is located in a millstone mountain water purification plant in the single-storey house area. The pipeline passing area is large, the landform is complex, and the shape is long and narrow.
The modeling is mainly considered from the following two points:
(1) Is the choice of breaking point: in theory, the long-distance pipeline is affected by the natural environment, water supply flow change, pipeline corrosion, unreliability, effectiveness of management measures, third parties and other factors, and pipeline rupture, leakage or overflow accidents can occur at any point along the pipeline. Therefore, any point of the pipeline can be selected by considering the breaking point in the modeling process.
(2) Is the selection of relevant simulation parameters after rupture: the actual overflow process caused by the broken pipeline is very complex, and is difficult to simulate by using a physical-mathematical formula under the general condition, so that the modeling is properly simplified in some cases, and the following conditions are set:
1) After the pipeline rupture accident occurs, the water inlet head is constant before the upstream water inlet gate is closed, and the rupture part leaks under the constant water head;
2) The amount of water remaining in the pipe after the gate is closed continues to leak until it is exhausted.
The starting point of the long-distance water delivery line of the millstone mountain is arranged on the right side of the millstone mountain water reservoir and is about 50.0m away from the dam, the central point Gao Chengyao 292.54m of the pipeline inlet is designed to have a water intake level of 298.0m, the normal water storage level of the reservoir is 318.0m, and the check flood level of the reservoir is 323.26m. The water heads at the inlets of the pipelines obtained under the three water level conditions are 5.46m, 25.46m and 30.72m respectively. On the basis of the conditions, the establishment of the pipeline rupture model takes the rupture point as the center, comprehensively considers infrastructures such as river channels, highways, civil houses and the like, and establishes the water seepage submerged model. The basic idea is as follows:
1.1 basic data processing: extracting terrain information of a submerged area, generating a terrain DEM, and establishing a calculation model triangular grid; treating buildings such as houses as a non-water passing unit; and extracting information such as road elevation, and setting the elevation in the calculation grid to simulate the water blocking effect of the road.
1.2 model calculation parameter settings: given pipeline parameters, setting the water level of a pipeline inlet reservoir, the position of a break point and the time for closing a gate after pipe breaking, once the pipeline breaks, the upstream flow regulating and pressure regulating valve closest to the break point is closed firstly, and the gate closing time is the time for closing the flow regulating and pressure regulating valve after the break.
1.3, simulation of the outflow process of the break point: including the outflow process before closing the gate and the outflow process after closing the gate.
1.4 building of submerged simulation model: establishing a submerged model of regional water flow, and simulating the submerged process of the water flow with the break flow process as an input condition.
1.5 flooding range and impact analysis: and analyzing the change process of the submerged water depth and the submerged range with time, and making influence assessment.
2. The specific flow is shown in figure 1.
3. Theoretical basis for model establishment
(1) Model construction content
1) Three-dimensional topography
In Arc info 9.0 or 10.0, a purchased digital elevation model (DEM, scale 1:10000) is used, a millstone long-distance water conveying pipeline is taken as a center, and the pipeline and surrounding area digital elevation models are established by extending 10km-15km to two sides respectively. And through superposition of other related information, a complete three-dimensional terrain is obtained, and basic support is provided for model simulation calculation and simple achievement display.
2) Development and application of pipeline burst inundation simulation model
The model development comprises four stages, wherein the first stage is submerged model principle analysis, including mathematical and physical model establishment, and the second stage is program development (code writing) of the model; the third stage comprises model debugging and parameter calibration; the fourth stage includes a model application.
(1) Water overflow simulation
And establishing a water overflow model according to the position of the rupture point, the flow velocity in the pipeline and the pipeline rupture mode by combining a pipeline correlation theory, a two-dimensional dynamic wave model and the like, and providing support for inundation analysis by simulating the overflow water quantity changing along with time. Pipeline rupture is generally simulated in a simplified manner using two modes:
a sudden rupture: causing a large amount of water to be gushed (instantaneous point source), but as the accident treatment proceeds, until the water in the pipeline (upstream of the breaking point to the closing position of the butterfly valve) is gushed out
b slow rupture: the water flow in the pipe is slowly gushed out (can be regarded as constant flow), but as the accident treatment progresses, the water in the pipeline (upstream of the breaking point to the closing position of the butterfly valve) is gushed out
(2) Flood evolution computation
a, surface confluence
The continuous equation:
in areas with a building distribution, this can be expressed by the following formula:
momentum equation:
in the X direction
Y direction
The inertia term is ignored (diffuse wave equation):
wherein u, v are the flow velocity in the x and y directions respectively; h is the water depth (m); h is the water surface elevation (m); h=h+z, z being the ground elevation; n is a Manning coefficient; q is the source and sink term (m/s), reflecting rainfall and overflow processes, etc.
Reflecting the influence of the building on the water flow, taking 0, A when the building is not water-blocking as the linear ratio of the water-blocking building area on the unit b The building area is the building area, A is the unit area; s is S fx ，S fy Friction gradient along x, y direction:
schematic diagram of surface unit discrete grid is shown in figure 2
Solving a diffusion wave equation by using an explicit differential format:
from (5) and friction gradient (x), the flow rates u and v in the x, y directions can be calculated, multiplied by the water depth h and the side length d of the cell, to obtain the flow rate Q entering and exiting the cell in the x and y directions 1 ，Q 2 ，Q 3 ，Q 4 : then calculating according to a water balance equation (1) to obtain the water depth h:
wherein:
Q 1 to Q 4 : flow into and out of the unit (positive in, negative in out)
q ij : the source sink of the unit (source isPositive and negative) is mainly rainfall, water exchange with a rain inlet, water exchange with a river network and the like.
b river confluence
For unsteady flows of the natural river and the channel confluence, solving according to a continuous equation of the one-dimensional unsteady flows and a momentum equation, namely a one-dimensional Save Vietnam equation set.
The continuous equation:
momentum equation:
substituting the continuous equation into the momentum equation is:
wherein: q-flow through river channel, m 3 S; v-river water flow rate, m/s; a-cross-sectional area of water, m 2 The method comprises the steps of carrying out a first treatment on the surface of the H-water head, river bottom Gao Chengjia water depth, m; a is that s Node surface area, m 2 ；S f Friction gradient, solved by the manning equation:
Where k=gn 2 N is Manning roughness, R is hydraulic radius, and m.
Solving the river (pipe) network flow problem expressed by the basic equation by using an explicit differential format: for (8), the following differential format is used:
and (3) finishing to obtain:
for (6), in order to facilitate node water level solving, the continuous equation is rewritten as:
the differential format is therefore:
wherein:
A S : calculating the water surface area of the control body for water balance;
∑Q t : the water balance calculates the algebraic sum of the flow rates of the control body.
The basic variables Q and H are solved using the flow equation (11) and the continuous equation (13).
(3) Inundation calculation simulation and analysis
Considering that factors of flooding caused by pipeline bursting have multiple characteristics, models are divided into a single-source model and a multi-source model during modeling. The single source model means that the flooding is only caused by the burst of a pipeline, and no other water source factors exist; the multisource model is mainly combined with a local river, and the pipe bursting source and other water sources such as river water flow are comprehensively considered. The flooding simulation analysis based on GIS and RS involves two key problems: simulation of submerged water surface and calculation of submerged range.
Single source model: and combining and establishing a three-dimensional terrain, taking a pipeline breaking point as a center, taking the overflow water quantity caused by pipeline breaking as the total water quantity, taking time dynamic evolution as a parameter, simulating the submerged range and the submerged area caused by analysis, and providing decision support for taking targeted measures.
Multisource model: if the pipe explosion water flow is converged and enters the river or bursts at the crossing river, the pipe explosion water flow must be uniformly considered with the river water flow to analyze and calculate the submerged range and area of multiple water sources, such as the rupture at the vicinity of the river or the crossing river.
The flooding simulation calculation method comprises the following steps: by referring to the advanced technology in the current river confluence and flooding theory, the flooding area (taking evolution time as reference) is calculated according to the related technology of current judgment flooding by referring to the distributed hydrologic model, and different submerged ground object types and corresponding areas are calculated by utilizing tools such as arc info and the like, so that data support is provided for flooding analysis and post-disaster evaluation.
The model calculation flow is shown in fig. 3;
3) Model development
The method has the advantages that the Fortran is combined with the VB to develop the model, the Fortran is adopted to write the main program, the method has the advantages of quick calculation, simple and quick programming of program codes and the like, but the interface friendliness is poor, and the VB can be adopted to write a good input/output interface, and the VB can be dynamically linked with the GIS (secondary development), so that the interface is friendly (part of the information work).
4) Model debugging and parameter calibration
On the basis of the development completion of the main program, the collected existing data is utilized to debug and calculate the model, and parameters are calibrated, so that good effect of model application is ensured.
5) Model application
(1) Analog computation
The submerged area and the submerged range caused by the pipeline rupture at a plurality of places can be simulated by calibrating model parameters, and the submerged area and the submerged range can be obtained by simulating the positions and the rupture modes of the pipeline and the surrounding environment of the rupture points as input conditions.
(2) Submerged range dynamic display and simulation
According to the established pipeline burst flooding simulation model, dynamically displaying the flooding range, the flooding area and the like in different time after the pipeline burst according to a time axis, and analyzing and evaluating corresponding flooding things (villages, roads, railways, farmlands and the like).
(2) Work emphasis
Pipeline accident location: the occurrence of the risk accident has uncertainty, and according to the preliminary result of risk assessment (high risk point of the pipeline), the model can input alternative conditions as the model according to the actual distribution position of the pipeline, and the arbitrary point of the pipeline is assumed to be the position where the accident is likely to occur.
Overflow simulation calculation: and adopting a single-source mode and a multi-source mode, and taking the pipeline cracking mode and the cracking position into consideration to carry out overflow calculation.
Determining an analog range: according to the primary analysis of the crossing position of the water pipe, the possible accident position and the regional topographic map, the simulation range is determined with emphasis, and decision support is provided for future pipeline operation scheduling, accident emergency plan processing and the like.
Selecting a model discrete method: taking actual demands of the model into consideration, a finite difference method and the like are adopted to perform dispersion of model equations.
(3) Technical route and working scheme
Work is carried out on the principle of taking the whole and the key points as the attention;
on the basis of widely collecting data and field investigation, project development adopts theoretical and practical method means, takes practical application as a starting point, combines advanced GIS, RS and other technologies, takes a flood evolution equation such as a san-View equation, a two-dimensional diffusion wave equation and the like as a basis, develops a pipeline burst flooding simulation model research, and provides decision support for guaranteeing safe operation and fault emergency treatment of a water pipeline.
4. Topographic data preprocessing
The simulation is of a larger scope, wherein the data related to the inundation simulation comprise terrain elevation points, water systems, water supply pipelines, roads, buildings and other ground features, and ArcGIS 9.0 software is adopted to extract the characteristics of the ground features. In the modeling process, the house is assumed to be impermeable to water, the house is treated as an impermeable boundary, and the ground elevation is arranged in the grid to reflect the water blocking effect of buildings such as roads. The topographic data processed by GIS software is shown as 4, and the local topography after processing the house is shown in FIG. 5.
5. Break flow process simulation
The simulation of the outlet flow needs to consider the actual situation of the accident, such as the opening and closing state of the gate, the current flow in the pipe and other factors. Referring to actual operation conditions, the outflow of the pipeline after the opening can be divided into an outflow before the gate is closed (the outflow before the gate is closed for short) and an outflow after the gate is closed (the outflow after the gate is closed). Since the principle of the two parts of analog streaming is different, it will be discussed separately in the following.
(1) Flow process before closing gate
The total design flow of the millstone mountain and water warehouse water supply engineering is 95.481 ten thousand m 3 /d, single tube design flow is 47.741 ten thousand m 3 /d, i.e. single tube inflow of 5.53m 3 And/s. From a hydraulic perspective, a single pipe network leak point can be considered as a small orifice free or submerged outflow, calculated using the orifice outflow equation:
wherein: Q-Water loss, m 3 /s；
A-leak area, m 2 ；
Free water pressure of H-pipe, m;
mu-orifice flow coefficient is typically between 0.60 and 0.62.
A series of experiments performed by researchers in the united kingdom, japan, etc. showed that there is the following empirical relationship between drain and node free water pressure:
Q＝λH 1.18 (0-2)
wherein: lambda-leakage coefficient, m 1.9 /s。
The harbine university of industry Zhou Jianhua et al proposes that the broken pipe flow should consist of two parts: the flow rate generated by the leakage area of the rigid material with the pressure is not changed in the first part, the flow rate generated by the leakage area of the flexible pipe with the pressure is increased in the second part, and the sum of the flow rates of the two parts is the leakage flow rate, which is expressed as follows:
Q＝Q 1 +Q 2 (0-5)
Wherein: a is that 1 The first part of the leakage area, m, is unchanged with pressure 2 ；
A 2 The second part of the area of leakage, m, varies with pressure 2 ；
And the characteristic coefficient of the k-leak area expanding and shrinking along with the pressure.
Zhou Jianhua and the like show that the leakage amount and H of the pipeline cracks or holes caused by pipe explosion and the like 0.5 In direct proportion, the area of the leakage opening will not change with the pressure change, and the orifice flow equation can be applied to leakage caused by pipe cracks of a pipe burst and the like. Considering that the pipelines adopted in the project are mostly rigid pipes and are simulated to be the outflow process after pipe explosion, the orifice outflow simulation outflow process is adopted, namely:
the key to flow process simulation is to determine the free water pressure H, which can be calculated using the following formula:
H＝H 0 -c 1 ×L×Q 0 (0-7)
wherein: h 0 -a head at the inlet of the pipe, m;
Q 0 flow at the inlet of the duct, m 3 /s；
The distance from the L-break point to the pipeline inlet is m;
c-Hazen-Williams coefficient, determined by the pipe;
d-diameter of the tube, m.
(2) Flow process after closing gate
After the gate is closed, the remaining water flow in the pipe gradually decreases with the leakage until it is completely discharged. The leak outflow process is also calculated according to the orifice outflow mode, i.e., the following equation:
wherein: mu-orifice flow coefficient, typically between 0.60 and 0.62;
h f Current head from free water in the pipe to the leak point, unit: m can be calculated by the following formula:
wherein: v-flow rate in the pipeline, m/s;
r-hydraulic radius, m;
j-head gradient;
c-the Xueteng coefficient;
n-pipeline roughness is 0.013 according to the pipeline material simulated at the time;
the distance from the free water surface position in the L-pipe to the break point is m;
d-diameter of the tube, m.
Because the diameter of the water supply pipeline in the engineering is larger than 2.0m, y in the equation of the Xueteng coefficient C is calculated by adopting a Pavlovi equation.
The complete flow process of the leakage point can be obtained by the simulation of the two stages, and the complete flow process is used as the input condition of the flooding model.
5.1, submerged model calculation principle
After water leakage leaks out of the pipeline, water flow is pushed to the periphery on the ground with dryness, and the simulation at the moment is equivalent to the water flow simulation of a flooding area and can be described by adopting two-dimensional shallow water flow. The equation is as follows:
wherein: z is the water level, and u and v are the flow velocity in the x and y directions respectively; u, V is the single wide flow in x and y directions, respectively;
vector of single wide flow, +.>
For its mould->
q is a source term considering factors such as rainfall; g is gravity acceleration, c is a thank coefficient, and f is a Ke Shili coefficient; τ wx 、τ wy The components of wind stress along the x and y directions, respectively, can be calculated using the following formula:
wherein: ρ a -air density;
c D -a drag coefficient;
Splitting the two-dimensional shallow water wave equation into the following two steps by adopting a cracking operator method; and then respectively solving the above-mentioned materials by adopting a proper method.
First step:
and step two:
and solving the numerical values of the two step equation sets, and adopting a control volume method of the non-uniform rectangular grid under a rectangular coordinate system. The urban area is normally a water-free ground, and the water quantity is exchanged between the break and the flood area under the condition of burst of the pipeline, and the following description takes the equation set of the second step as an example, as shown in fig. 6:
first, the x-direction momentum equation in (0-14) is discretized, and the interface between the units I and J is taken as an example as follows:
wherein: the subscript "0" indicates the known value at the beginning of the time.
And (3) finishing and simplifying to obtain:
U＝δ 0 (Z I -Z J )+β 0 (0-16)
multiplying the above equation by deltay yields the flow from unit I into unit J as:
Q X ＝δ X (Z I -Z J )+β X (0-17)
the flow rate of the unit K flowing to the unit J is obtained by dispersing the y-direction momentum equation in the pair (0-14) in the same way:
Q Y ＝δ Y (Z K -Z J )+β Y (0-18)
discrete equations of continuity in (5.3-14) are available:
simplifying and obtaining:
wherein: a is the area of cell J, ΣQ i The algebraic sum of the amounts of water flowing into the unit J per unit time including rainfall is represented.
6. Breach flow analysis
Taking a flat house area and a five-element city break as an example, after the break occurs, the outflow process is considered according to the front and rear states of closing the flow regulating and pressure regulating valve respectively. The calculation flow before closing the flow regulating and pressure regulating valve is shown in fig. 7, and the calculation flow after closing the flow regulating and pressure regulating valve is shown in fig. 8.
According to the calculation flow, the outflow flow and the head loss at the flat house area and the five-element break before closing the flow regulating and pressure regulating valve are shown in table 1.
According to the calculation, when the reservoir water level is the check flood level, the first pressure stabilizing well and the second pressure stabilizing well both play a role in regulating pressure, and the water head at the corresponding position is regulated to the overflow water level. At this time, the water head at the first pressure stabilizing well is 278.00m, the water head at the second pressure stabilizing well is 239.00m, and the total water head and the free water head along the process before and after pressure regulation are shown in fig. 9.
Table 1 single tube break out flow calculation table for flat area and five elements city
Before the upstream flow regulating and regulating valve is closed, the upstream water level is constant, and the water purifying head at the break point is correspondingly constant, so that the break flow is relatively constant, and after one hour, the break point pressure is reduced and the break flow is reduced until the water purifying head at the break point is close to zero, and the break point is not outflow. The simulation assumes that the gate is closed instantaneously, wherein water is not leaked at the break after the valve is closed for 2 hours in the bungalow area, and water is not leaked after the valve is closed for 1 hour and 20 minutes in the five-element city, and the specific simulation process is as follows.
7. Inundation simulation and result analysis
The simulation mainly considers the selection of typical cases of pipeline rupture inundation simulation from two aspects:
the areas with dense population and developed economy are submerged, so that large losses are easily caused, and important attention is needed;
the weak section (point) of the long pipeline is relatively easy to generate the phenomenon of tube explosion, and important attention is also needed.
In summary, the simulation selects the five-element urban area and the Harbin bungalow area as typical areas with dense population, and simultaneously selects the areas with relatively weak pipelines (connected with the pipeline water hammer protection research results) as the explosive areas to respectively perform submerged simulation so as to reflect the influence degree and range of the explosive tubes and provide basis for emergency decision.
7.1 open-rise district of Harbin city
The flat area in Harbin city is located at the tail end of a long-distance pipeline, buildings such as houses are concentrated, population density is high, and the flat area is one of areas needing important precaution. The simulated break positions and the simulated simulation ranges are shown in fig. 10, the building distribution is shown in fig. 11, the simulated regional topography is shown in fig. 12, the upper right corner of the region is a river course, the whole regional topography presents a middle height and two side bottoms in the north-south direction, the break positions are located on the center high ground, a population dense region is arranged around the region, and large losses are caused by flooding. The pipeline distance between the break point and the water taking point of the millstone mountain water warehouse is 173.2km. The three working conditions are set up at this time to simulate respectively, wherein the upstream millstone mountain reservoir takes the most unfavorable water level state, namely the millstone mountain reservoir water level is check flood level 323.26m:
(1) The water level of the millstone mountain and water reservoir is 323.26m, and the normal water delivery flow of a single pipe is 5.53m 3 S, breaking the single tube, and closing the upstream nearest flow regulating and pressure regulating valve after the pipeline is broken for 1 hour;
(2) The water level of the millstone mountain and water warehouse is 323.26m, and the normal water delivery flow of the double tube is 11.06m 3 S, the double tube breaks, and the upstream nearest flow regulating and pressure regulating valve is closed after the pipeline breaks for 1 hour;
(3) The third working condition is the most adverse condition, the water level of the millstone mountain water reservoir is 323.26m, and the normal water delivery flow of the double tube is 11.06m 3 And/s, the upstream nearest flow regulating valve is not closed for a long time (2 hours) after the double tube is broken.
The probability of double-pipe rupture in actual operation is lower, so the first working condition (working condition 1) is a general condition, the second working condition (working condition 2) is a rare condition, the third working condition (working condition 3) is the most unfavorable condition, and rupture flooding simulation is respectively carried out on the three working conditions.
Working condition 1:
the process of leakage flow at the break under the first working condition is shown in fig. 13. Before the gate is closed, the inlet head of the water supply pipe is constant, and leakage flows out at constant flow rate; when the gate is closed, the pressure of the water flow in the pipe is reduced, the outflow flow of the leakage outlet is reduced, and the maximum flow in the whole leakage process is 11.6m 3 S for a total time of 2 hours.
The maximum leakage flow rate of the breach and the maximum flooding range were achieved within 1 hour after the pipeline was ruptured to close the gate, and the flooding process within 2 hours after the simulated breach occurred was as shown in fig. 14. The calculation shows that after the pipeline at the selected position is broken, the water flow submerged range extends along the northeast direction of the breaking point and finally enters the northeast corner river channel, fewer buildings are arranged in the submerged area, the water flow is quickly converged into the river channel through the area, and the detention time is short.
The average submerged water depth, the total water quantity of the submerged area and the change law of the submerged area with time under the working condition are shown as figure 15, and the average submerged water depth is 0.22m after 2 hours of break; the maximum submerged depth is 0.51m when the submerged water is just broken; the submerged area increases with the increase of the water quantity of the break, about 0.27km 2 。
Working condition 2:
the process of the leakage flow rate of the break under the second working condition is shown in FIG. 16, and the maximum flow rate in the whole leakage process is 23.3m 3 S, which occurs before the shutter closes.
As shown in FIG. 17, the flooding simulation process within 2 hours after the break occurs, the water flow flooding direction is similar to the working condition 1, and finally the water flow is converged into the northeast corner river channel, and the flooding range is obviously larger than the working condition 1.
The average submerged water depth, the total water quantity of the submerged area and the change law of the submerged area with time under the working condition are shown in figure 18, and the average submerged water depth is 0.34m after 2 hours of break; the maximum submerged depth is 0.65m when the submerged water just breaks; the submerged area increases with the increase of the water quantity of the break, about 0.36km 2 。
Working condition 3:
the process of the leakage flow rate of the break under the third working condition is shown in FIG. 19, and the maximum flow rate in the whole leakage process is 23.3m 3 And/s, the gate is not closed. Because the whole process is constant flow, in order to keep consistent with the first two working conditions, the time is only intercepted for 2 hours.
Since the simulation of the first two working conditions shows that after the selected point is broken, the water flows to the northeast corner, and the influence on the left area is small, the calculation area is concentrated in the right area in the working condition.
The flooding process within 2 hours after the simulated break occurs is shown in fig. 20, the water flow flooding direction is similar to the working condition 1, and finally the water flows into the northeast corner river channel, and the speed and the range of the flooding are obviously larger than those of the former two working conditions. The average submerged water depth of the submerged area under the working condition and the total water quantity of the submerged area are shown in figure 21. As can be seen from the figure, after 2 hours of breach, the average submerged water depth is 0.39m; the maximum submerged depth is 0.65m when the submerged water just breaks; the submerged area increases with the increase of the water flow at the break, about 0.43km 2 。
3 comparison of working conditions:
the above was simulated for 3 cases, namely, 1 hour gate off when a single tube breaks, 1 hour gate off when a double tube breaks, and 3 cases, namely, when a double tube breaks for a longer period of time without gate off, the flooding trends of the 3 working conditions are approximately the same, the directions of the flooding ranges are approximately the same, the flooding degrees are different, and the flooding conditions after 2 hours break for the 3 working conditions are shown in table 2. The submerged areas caused by the 3 working conditions are large, the average submerged water depth exceeds 0.20m, and if the duration is long, certain loss is caused.
Table 2 comparison table for three conditions of flooding in flat area
7.2 five-element urban area
The five-way urban area break positions and the model simulation ranges are shown in fig. 22, the building distribution is shown in fig. 23, the simulated area topography is shown in fig. 24, the right side of the area is mountain area high land, the left side of the area is low-lying area, and the break points are located on the central high slope. The pipeline distance between the break point and the water taking point of the millstone mountain of the water conveying pipeline is 73.7km, and the break point is 101.8km from the water purifying plant. The working condition set by the simulation is the same as that of the single-storey house:
(1) The water level of the millstone mountain and water reservoir is 323.26m, and the normal water delivery flow of a single pipe is 5.53m 3 S, breaking the single tube, and closing the upstream nearest flow regulating and pressure regulating valve after the pipeline is broken for 1 hour;
(2) The water level of the millstone mountain and water warehouse is 323.26m, and the normal water delivery flow of the double tube is 11.06m 3 S, the double tube breaks, and the upstream nearest flow regulating and pressure regulating valve is closed after the pipeline breaks for 1 hour;
(3) The third working condition is the most adverse condition, the water level of the millstone mountain water reservoir is 323.26m, and the normal water delivery flow of the double tube is 11.06m 3 And/s, the upstream nearest flow regulating valve is not closed for a long time (2 hours) after the double tube is broken.
Working condition 1:
as shown in FIG. 25, before the gate is closed, the water head at the inlet of the water supply pipe is constant, the leakage flows out at a constant flow rate, and after the gate is closed, the pressure of the water in the pipe is reduced, the outflow flow rate of the leakage is reduced, and the maximum flow rate in the whole leakage process is 18.5m 3 And/s. The period from the occurrence of the breach to the time before closing the gate, the leakage flow rate of the breach is the largest, the resulting flooding range is also the largest, and the flooding process within 1 hour and 20 minutes after the occurrence of the simulated breach is shown in fig. 26. Calculations indicate that after the selected location pipe breaks, the submerged range of the water flow extends in both the west and south directions along the break point, with fewer buildings in the submerged area.
The average submerged depth, total submerged water amount and submerged area change process with time of the submerged area under the working condition are shown in fig. 27. As can be seen from the graph, after 1 hour and 20 minutes from the break, the submerged water depth tends to be stable, and the average submerged water depth is 0.22m; the maximum submerged depth is 0.78m when the submerged water just breaks; the submerged area increases with the water quantity of the break, and after 1 hour and 20 minutes of break, the submerged area is about 0.46km 2 。
Working condition 2:
the process of the leakage flow rate of the break under the second working condition is shown in FIG. 28, and the maximum flow rate in the whole leakage process is 37.1m 3 S, which occurs before closing the shutter. The flooding process within 1 hour and 20 minutes after the simulated break occurs is shown in FIG. 29, and the water flowsThe flooding direction is similar to condition 1. The flooding range at this time is significantly greater than operating condition 1, with most of the flooding area being devoid of buildings.
The average submerged depth, total submerged water amount and submerged area change process with time of the submerged area under the working condition are shown in fig. 30. As can be seen from the graph, after 1 hour and 20 minutes from the break, the submerged water depth tends to be stable, and the average submerged water depth is 0.26m; the maximum submerged depth is 0.80m when the submerged water is just broken; the submerged area increases with the water quantity of the break, and after 1 hour and 20 minutes of break, the submerged area is about 0.91km 2 。
Working condition 3:
the process of the leakage flow rate of the break under the third working condition is shown in FIG. 31, and the maximum flow rate in the whole leakage process is 37.1m 3 And/s, the gate is not closed for a long time. Because the whole process is constant flow, in order to keep consistent with the first two working conditions, the time is only intercepted for 1 hour and 20 minutes.
The simulation of the first two working conditions shows that after the selected point is broken, the influence of water flow on the north part is small, so that the calculation area is concentrated in the south part area under the working conditions.
The flooding process within 4 hours after the simulated break occurs is shown in fig. 32, the water flow flooding direction is similar to the working conditions 1 and 2, and finally the water flows to the south and the west, and the flooding speed and the flooding range at the moment are obviously larger than those of the first two working conditions. The average submerged water depth, total water quantity and time-dependent submerged area change process of the submerged area under the working condition is shown in fig. 33, and the average submerged water depth is 0.25m after 4 hours of opening; the maximum submerged depth is 0.82m when the submerged water just breaks; the submerged area increases with the increase of the water flow at the break, and after 4 hours at the break, the submerged area is about 3.05km 2 。
3 comparison of working conditions:
the above was simulated for 3 cases, i.e., 1 hour gate off when a single tube was broken, 1 hour gate off when a double tube was broken, and no gate off when a double tube was broken for a long time, respectively, and the comparison of the three conditions at 1 hour and 20 minutes is shown in table 3 in order to maintain the consistency in time. The submerged areas in the 3 working conditions are larger, and the average submerged water depth is smaller because the current submerged area is broader in topography. When the flooding time lasts longer, a certain loss is caused.
Table 3 five elements 3 kinds of working condition inundation condition comparison table
7.2.1 simulation of the weak segment breach 1
According to the analysis and calculation result of the hydraulic transition process of the pipeline, the position of the weak section break 1 and the simulation range of the model are shown in fig. 34, and the weak point is positioned between the No. 1 pressure stabilizing well and five cities, and the pile number is 5+900. The building distribution is shown in fig. 35. The simulated regional topography of the model is shown in fig. 36, the northeast part of the region is a mountain area, the slope with the elevation between 190 and 200m is below the mountain area, and the break point is positioned on the central slope. Because this section is the weak district, and the pipeline breaks relatively easily, and this region is located mountain area, and the population is less, adopts double-barrelled broken as the simulation condition this simulation, and the settlement parameter is: the water level of the millstone mountain and water warehouse is 323.26m, and the normal water delivery flow of the double tube is 11.06m 3 And/s, the double pipe is broken, and the upstream flow regulating and pressure regulating valve is closed after the pipe breaks for 1 hour.
Under the set adverse conditions, the breach leakage flow process is shown in fig. 37. Before the gate is closed, the water inlet head of the water supply pipe is constant, leakage flows out at constant flow, after the gate is closed, the pressure of the water flow in the pipe is reduced, the outflow flow of the leakage outlet is reduced, and the maximum flow in the whole leakage process is 41.0m 3 And/s, since the break point is closer to the upstream inlet point, the residual water flow in the pipeline after closing the gate can flow through the break point in a shorter time, and the leakage time is relatively shorter. The maximum leakage flow rate of the breach occurred within several hours before the gate was closed, and the resulting flooding range was also maximum, as shown in fig. 38 for the flooding process within 1 hour and 20 minutes after the simulated breach occurred. Calculations indicate that after the selected location of the pipe has been ruptured, the water flow The submerged range extends to the west and south along the break point, and after 1 hour and 20 minutes, the submerged range can submerge part of building areas, the average submerged water depth is 0.21m, and the submerged area is 0.71km 2 。
7.2.2 simulation of weak segment break 2
The weak section break 2 position and the model simulation range are shown in fig. 39, and the weak point is positioned between the No. 2 pressure stabilizing well and the Harbin city, and pile number is 143+700. The distribution of buildings within the area is shown in fig. 40. The simulated area topography of the model is shown in fig. 41, the area is the groove topography, and the break points are positioned in the low-lying grooves. The weak area also adopts the most unfavorable condition as the simulation condition, and the set parameters are as follows: the water level of the millstone mountain water warehouse is 323.26m, and the normal water delivery flow of the double tube is 11.05m 3 And/s, the double pipe is broken, and the upstream flow regulating and pressure regulating valve is closed after the pipe breaks for 1 hour.
Under the set adverse conditions, the breach leakage flow process is shown in fig. 42. Before the gate is closed, the water inlet head of the water supply pipe is constant, leakage flows out at constant flow, after the gate is closed, the pressure of the water flow in the pipe is reduced, the outflow flow of the leakage outlet is reduced, and the maximum flow in the whole leakage process is 30.4m 3 And/s. The flooding process within 1 hour and 20 minutes after the simulated break occurs is shown in fig. 43, and the calculation shows that after the pipeline at the selected position breaks, the flooding range of the water flow advances along the topographic groove, the average flooding water depth is 0.46m, and the flooding area is 0.36km 2 . The building is positioned on the high land beside the groove and is not affected by flooding.
8. Calculation result reliability analysis
The flow in the actual nature is simulated by adopting a numerical model, and certain errors are necessarily present. In terms of the form of error, it is mainly derived from three parts: errors of actual measurement data, errors of actual reflection degree of mathematical theory on the nature and errors of numerical calculation models. For error analysis, there are two methods, namely a theoretical analysis method and a comparison method with an actual measurement value. The model adopted by the project has second-order precision in theory, and the simulation error mainly comes from the topographic measurement error. In addition, because no engineering accident actual measurement data is subjected to comparative analysis, a parameter sensitivity analysis method is mainly adopted for reliability analysis of the model.
The main parameter of the model is the roughness, which influences the travelling speed of water flow on the ground. The degree of influence of the change in the roughness parameter on the model simulation result was considered by adjusting the roughness to 0.015, 0.020, and 0.030. If the adjustment of the parameters has little influence on the calculation result, the parameters are insensitive to the simulation result. The flooding degree is controlled by the topography and the outflow rate, and the outflow process determines the flooding condition, which indicates that the model obtains similar results under various parameter conditions, and the results are reliable. The parameter adjustment scheme is simulated by taking a single pipe break of a single-storey house area for 1 hour as a reference for closing a gate.
(1) Influence of roughness on average submerged depth
The flooding depth is the final factor in the flooding assessment, and directly determines the flooding loss, so the flooding areas under three roughness parameters are considered for comparison, the response of the test model to the working condition is tested, and the average flooding depth in the flooding area is shown in figure 44.
The tendency is the same at the three roughness values in fig. 44, but the water flow rate increases due to the reduction of the roughness value, and rapid water accumulation is easily formed in a local area. In general, the average water depths in the three cases differ by less than 5cm, which indicates that the trends of the submerged water depths in the three cases are consistent, the submerged depths are approximately the same, and the model calculation has higher precision.
(2) Influence of roughness on submerged area
The flooding directly affects the flooding loss, and figure 45 is a comparison of flooding at three roughness rates.
As can be seen from FIG. 45, the submerged areas under the three roughness rates have approximately the same trend, the submerged areas have larger differences only in local areas, and the differences are not more than 0.05km at most moments 2 The model was shown to be less sensitive to roughness in this scenario.
The main factors affecting flooding are topography factors and breach flow factors. When the approximate situation of flooding after the break flow is determined, the model adopts various roughness to verify the conclusion, and the model has higher reliability. The simulation result can be used as a reference basis for actual decision making.
9. Knot (S)
From the simulation of the 4 exemplary examples described above, the following conclusions can be initially drawn:
(1) After the horizontal house area breaks, water flows towards the sparse population area, the water flows rapidly pass through the sloping field and finally flow into the river channel, and under the conditions of single pipe break, double pipe break and gate opening, the average submerged water depth is 0.22m, 0.34m and 0.39m respectively, and the submerged area is 0.27km respectively 2 、0.36km 2 、0.43km 2 . The submerged water depth is larger, and larger loss is easy to cause.
(2) After the pipeline in the five-way city breaks, the water flows in a direction away from the five-way city, and less water flows through the regional buildings. Under the first two working conditions, the average submerged water depth is 0.22m and 0.26m respectively, and the submerged area is 0.46km respectively 2 And 0.91km 2 . Under the least adverse working condition, the average submerged water depth after 4 hours of break is 0.25m, and the submerged area is 3.05km 2 Although the submerged water depth is smaller than that of the flat area, the submerged area is larger, and the loss caused by the submerged area is not ignored.
(3) For the weak area break 1, the slope state where the break point is located diverges, the water flow submerges the flowing range greatly, the influence on partial buildings is large, the submerged water depth is relatively small due to the large water flow coverage area, the average submerged water depth is about 0.21m, the area is a mountain area, the population is small, and the economic loss caused by the small population is correspondingly small.
(4) For the weak area break 2, due to the groove topography, the submerged flow direction of the water flow is concentrated, the water flow advances along the groove, and the average submerged water depth is 0.46m. Although the submerged depth is large, the submerged area is positioned in the valley bottom of one groove, no building exists, and the submerged loss is easy to control.
The break inundation simulation only considers the problem of break outflow, if adverse weather factors such as heavy rain are encountered while breaking, the loss caused to the flat house area and the five-element urban area is larger, and corresponding engineering measures are adopted to dredge the break water flow, so that the loss is reduced to the minimum.
Claims (6)
1. The method for calculating the rupture model of the long-distance gravity flow large-diameter water supply pipeline is characterized by comprising the following steps of:
s1: after the pipeline rupture accident occurs, before the upstream water inlet gate is closed, calculating a gate rupture point seepage water quantity model under the condition that the water inlet head is constant;
s2: calculating a model of continuous leakage of the residual water in the pipeline until the water is exhausted after the gate is closed;
s3: the starting point of the long-distance water delivery line of the millstone mountain is arranged on the right side of the millstone mountain water reservoir, the distance from the starting point to the dam is 50.0m, the elevation of the central point at the inlet of the pipeline is 292.54m, the designed water intake level is 298.0m, the normal water storage level of the reservoir is 318.0m, the check flood level of the reservoir is 323.26m, and the water heads at the inlets of the pipeline obtained under the three water level conditions are 5.46m, 25.46m and 30.72m respectively;
S4: on the basis of S3, a rupture model of a pipeline is built by taking a rupture point as a center, and a seepage inundation model is built by comprehensively considering river channels, highways and civil house infrastructures;
s5: calculating and analyzing the open traffic of the flat area and the five-way city;
s6: a GIS frame of a double-object sharing structure for realizing the sharing of the GIS object and the model object;
s7: providing spatial analysis and spatial information management by GIS objects and models;
s8: the GIS object and the model provide a core function of simulation analysis of a physical mechanism and a space-time process professional model;
space-time attribute information management and analysis are provided by GIS objects and models, a GIS frame of a double-object sharing structure is constructed, and the problem of 'seamless' integration of GIS and professional models is solved;
s9: the GIS object and the model are used for solving the problem of on-demand expansion of the GIS object and the analysis function, and a GIS with a multidimensional space-time structure is created;
s5, calculating and analyzing the opening flow of the flat area and the five-element city, wherein the opening flow is divided into two states of a state before closing the flow regulating and pressure regulating valve and a state after closing the flow regulating and pressure regulating valve;
the calculation flow before closing the flow regulating and pressure regulating valve is as follows:
s51: giving a water level reservoir, and generating a breach;
s52: whether the breach is downstream of the pressure stabilizing well; if yes, whether the water head of the second pressure stabilizing well exceeds 239 meters or not is judged, and if not, whether the water head of the first pressure stabilizing well exceeds 278 meters or not is judged;
S53: if yes, calculating the water level at the upstream end of the break point according to 239 meters, wherein the acting position is a No. 2 pressure stabilizing well; if not, whether the water head of the first pressure stabilizing well exceeds 278 meters is checked;
s54: if yes, calculating the water level of the upstream end of the break point according to 278 m, wherein the acting position is a No. 1 pressure stabilizing well, and if not, calculating the water level of the upstream end of the break point according to the water level of a reservoir, and acting at the inlet of a pipeline at the acting position;
s55: calculating the head loss from the action position to the break edge;
s56: calculating a water purifying head;
s57: calculating a break outflow according to a formula;
the calculation flow after closing the flow regulating and pressure regulating valve is as follows:
s511: a breach occurs;
s512: the nearest upstream flow regulating and pressure regulating valve of the break point;
s513: closing the nearest upstream flow regulating valve;
s514: searching the highest elevation point between the current water flow upstream point and the break point, and taking the highest elevation point as a water head acting position;
s515: the total water quantity TQ between the upstream point and the break point of the water flow;
s516: the remaining water after one hour step is:
dq=tq-Q τ; if dQ is greater than 0, calculating the head loss along the city from the action position to the break point; if dQ is less than 0, stopping calculation;
s516: according to the result of S514, calculating the average flow of the pipeline according to a Manning formula;
S517: calculating a water purifying head; if the water purification head is larger than 0, calculating the breach outflow according to a formula, and if the water purification head is not larger than 0, stopping calculating.
2. The method for calculating the rupture model of the long-distance gravity flow large-diameter water supply pipeline according to claim 1, wherein after the S1 pipeline rupture accident occurs, the water inlet head is calculated to be constant before the upstream water inlet gate is closed, and the water inlet head leakage amount model at the rupture point of the gate is calculated as follows:
wherein: q-water loss; a is the area of the leakage opening; h is the free water pressure of the pipeline; mu is the orifice flow coefficient, the value is between 0.60 and 0.62, g is gravity acceleration;
the key of flow process simulation is to determine the free water pressure H, which is calculated by the following formula:
H＝H 0 -c 1 ×L×Q 0 (2)
c 1 ＝10.667L/(c 1.852 d 4.87 ) (3)
wherein: h 0 Is the water head at the inlet of the pipeline; q (Q) 0 Is the flow at the inlet of the pipeline; l is the distance from the break point to the pipeline inlet; c is a Hazen-Williams coefficient, and is determined by the pipe; d is the diameter of the pipeline, mu is the orifice flow coefficient, and A is the leak area.
3. The method for calculating a rupture model of a long-distance gravity flow large-diameter water supply pipeline according to claim 1, wherein the model that the residual water in the pipeline continues to leak until exhausted after the S2 gate is closed is as follows:
Wherein: mu is the orifice flow coefficient, the value is between 0.60 and 0.62, the area of the A-leakage opening is, g is gravity acceleration;
h f the current head from the free water surface in the pipe to the leakage point is calculated by the following formula:
wherein: v is the flow rate in the pipeline; r is the hydraulic radius; j is the head gradient; c is the thank you coefficient; n is the pipeline roughness, and is taken as 0.013 according to the pipeline material simulated at the time; l is the distance from the free water surface position in the pipe to the break point; d is the diameter of the pipeline, and y in the equation of the Xueteng coefficient C is calculated by adopting a Pavlovinyl equation because the diameter of the water supply pipeline of the engineering is larger than 2.0 m.
4. The method of long distance gravity flow large pipe diameter water supply pipe rupture model calculation according to claim 1, wherein said S4 comprises the sub-steps of:
s41: establishing a two-dimensional shallow water wave equation of a water submerged model;
s42: splitting the two-dimensional shallow water wave equation into two steps by adopting a cracking operator method; and then respectively solving the two problems by adopting a differential method.
5. The method for calculating a long-distance gravity flow large-diameter water supply pipeline rupture model according to claim 4, wherein the water submerging model of S41 is:
After water leakage leaks out of the pipeline, the water flow is pushed to the periphery on the ground which is dry, the simulation at the moment is equivalent to the water flow simulation of a flooding area, the two-dimensional shallow water flow is adopted for description, and the equation is as follows:
wherein: z is the water level, and u and v are the flow velocity in the x and y directions respectively; u, V is the single wide flow in x and y directions, respectively;
vector of single wide flow, +.>
For its mould->
q is a source term considering rainfall factors; g is gravity acceleration, c is a thank coefficient, and f is a Ke Shili coefficient; τ wx 、τ wy The components of wind stress along the x and y directions are calculated by the following formulas:
wherein: ρ a Is air density; c D Is the resistance coefficient;
is a wind speed vector at a height of 10m from the water surface.
6. The method for calculating the rupture model of the long-distance gravity flow large-diameter water supply pipeline according to claim 4, wherein the equation is split into two steps by adopting a rupture operator method in the step S42;
first step:
and step two:
wherein Z is the water level, and u and v are the flow velocity in the x and y directions respectively; u, V is the single wide flow in x and y directions, respectively;
vector of single wide flow, +.>
For its mould->
q isA source term that considers precipitation factors; g is gravity acceleration, c is a thank coefficient, and f is a Ke Shili coefficient; τ wx 、τ wy The components of wind stress in the x and y directions, respectively. />
Priority Applications (1)
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108256193A (en) * | 2018-01-10 | 2018-07-06 | 中国水利水电科学研究院 | A kind of river flood due to dam-break one, two-dimensional numerical model coupling analytical method |
| CN108595799A (en) * | 2018-04-12 | 2018-09-28 | 福建省水利水电勘测设计研究院 | A kind of large size is opened flat lock and drains off floodwaters the method for numerical simulation of moisture-proof traffic control |
| CN110197017A (en) * | 2019-05-17 | 2019-09-03 | 长安大学 | A kind of urban river rubber dam group's Ecology regulation method |
| CN111125631A (en) * | 2019-09-26 | 2020-05-08 | 深圳市东深电子股份有限公司 | Water resource calculation scheduling method based on target water level and flow |
-
2020
- 2020-09-02 CN CN202010912356.8A patent/CN112036043B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108256193A (en) * | 2018-01-10 | 2018-07-06 | 中国水利水电科学研究院 | A kind of river flood due to dam-break one, two-dimensional numerical model coupling analytical method |
| CN108595799A (en) * | 2018-04-12 | 2018-09-28 | 福建省水利水电勘测设计研究院 | A kind of large size is opened flat lock and drains off floodwaters the method for numerical simulation of moisture-proof traffic control |
| CN110197017A (en) * | 2019-05-17 | 2019-09-03 | 长安大学 | A kind of urban river rubber dam group's Ecology regulation method |
| CN111125631A (en) * | 2019-09-26 | 2020-05-08 | 深圳市东深电子股份有限公司 | Water resource calculation scheduling method based on target water level and flow |
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