A 3D Digital Modeling Method for Underground Pipelines Based on GIS and BIM

Abstract

This invention discloses a 3D digital modeling method for underground pipelines based on GIS and BIM, comprising: acquiring BIM parameter data and geospatial data of road engineering to generate an integrated spatial data base of roads, buildings, and terrain; acquiring BIM parameter data of pipeline engineering to generate an integrated spatial model of pipeline network and terrain; acquiring surface runoff parameter data; performing hydraulic and hydrological coupled calculations to generate regional flooding simulation results; identifying pipeline network defects and generating pipeline network renovation plans; and performing lightweight processing on multi-source data to generate fused display data. This invention achieves deep integration of BIM engineering parameters and GIS geospatial data, as well as full-process simulation analysis of regional flooding and intelligent pipeline network renovation.

Description

Technical Field

[0001] This invention relates to the field of urban flood control and drainage network engineering technology, and more specifically, to a three-dimensional digital modeling method for underground pipelines based on GIS and BIM. Background Technology

[0002] Urban flooding is a significant issue affecting the safe operation of cities. Analyzing urban flooding in different areas and developing pipeline renovation plans are crucial means of flood prevention and control.

[0003] In existing technologies, urban flooding analysis methods typically manage and process road engineering data, underground pipe network data, and geospatial data independently. Road vertical design parameters, pipe network drainage capacity parameters, and topographic runoff characteristics are stored in different data systems, lacking a unified spatial benchmark and topological correlation. Pipeline defect identification and renovation plan formulation rely on manual inspection and experience-based judgment.

[0004] The aforementioned existing technologies have the following drawbacks: First, the incompatibility of multi-source data formats and the lack of uniform spatial coordinates make it impossible to accurately match roads, pipe networks, and terrain in the same analysis scenario, resulting in spatial deviations in the input data for urban flooding simulation. Second, traditional urban flooding analysis only calculates drainage capacity for single points or single pipe sections, failing to complete the coupled extrapolation of the entire process from surface runoff, stormwater inflow, pipe network drainage to water accumulation at the area scale, leading to vague positioning of urban flooding risk points and difficulty in tracing the causes of water accumulation. Third, the renovation plan cannot be previewed before implementation, easily resulting in insufficient targeted renovation and drainage effects that do not meet expectations. Summary of the Invention

[0005] This invention provides a 3D digital modeling method for underground pipelines based on GIS and BIM, which solves the technical problems in related technologies such as the lack of multi-source spatial data fusion means in urban area flooding analysis, insufficient coupling between pipeline hydraulic calculation and surface runoff process, and the lack of quantitative basis and effect prediction capability for pipeline renovation schemes.

[0006] This invention discloses a three-dimensional digital modeling method for underground pipelines based on GIS and BIM, including: acquiring BIM parameter data and geospatial data of road engineering in the target area; unifying the spatial coordinate reference of the road engineering BIM parameter data and geospatial data; and overlaying and registering the three-dimensional linear model of the road engineering, the three-dimensional outline model of the building, and the three-dimensional terrain surface to generate an integrated spatial data base of roads, buildings, and terrain. Obtain BIM parameter data of underground pipe network in the target area, map the spatial coordinates of each node and pipe segment in the pipe network BIM parameter data to a unified spatial coordinate reference, generate a pipe network spatial topology map based on the upstream and downstream connection relationship between each node, and spatially overlay the pipe network spatial topology map with the terrain surface to generate an integrated spatial model of pipe network and terrain. Based on the integrated spatial data base of roads, buildings, and terrain and the integrated spatial model of pipelines and terrain, the surface of the target area is divided into water catchment zones, the comprehensive runoff coefficient of each water catchment zone is calculated, the correspondence between each water catchment zone and the storm drain is established, and surface runoff parameter data is generated. Based on the design rainfall process data and surface runoff parameter data, the surface runoff of each catchment area is calculated at each time step. The inflow sequence of each rainwater inlet is used as the boundary condition. Based on the integrated spatial model of pipe network and topography, the hydraulic and hydrological coupling calculation is performed using the pipe network unsteady flow solution method based on the Saint-Venant equations to generate the simulation results of regional flooding. Based on the simulation results of local flooding, the flow capacity utilization rate of each pipe section is calculated, pipe sections with insufficient flow capacity and overflow nodes are marked, the cause of overflow is determined and the parameters for modification measures are generated, and the pipeline network modification plan is generated by summarizing the results.

[0007] Furthermore, the process of unifying the spatial coordinate reference of the road engineering BIM parameter data and geospatial data includes: Using the geodetic coordinate system in the geospatial data as the reference coordinate system, the local engineering coordinates of each element in the road engineering BIM parameter data are mapped to the reference coordinate system through a coordinate transformation matrix. The terrain surface is trimmed and fitted according to the three-dimensional line shape of the road centerline, and the building outline is projected onto the terrain surface to obtain its bottom elevation, thus completing the positioning of the road, building and terrain in the same coordinate space. When the vertical design parameters of the road, the building layout, or the terrain data change, the changed parameter data is obtained, and the geometric parameters and spatial topological relationships of the corresponding elements in the integrated spatial data base of the road, building, and terrain are incrementally updated.

[0008] Furthermore, the pipeline network spatial topology map records the connection node identifiers, flow directions, and the number of incoming and outgoing pipeline segments for each pipeline segment. The flow direction is determined based on the difference in pipe bottom elevation between the start and end points of each pipe segment. The end with the higher pipe bottom elevation is the upstream node, and the end with the lower pipe bottom elevation is the downstream node. When the slope of the pipe segment is zero, the flow direction is assigned according to the design document. When generating the integrated spatial model of the pipeline network and terrain, a three-dimensional solid geometric model of each pipe segment is generated based on the pipe diameter and pipe material parameters of each pipe segment, and a three-dimensional solid geometric model of each manhole is generated based on the manhole diameter and manhole depth parameters. The three-dimensional solid geometric models of each pipe segment and the three-dimensional solid geometric models of each manhole are assembled according to the connection relationship in the pipeline network spatial topology diagram and spatially superimposed on the terrain surface.

[0009] Furthermore, the process of dividing the catchment area is as follows: The surface water flow direction of each grid cell is calculated based on the elevation value of each grid cell in the topographic DEM data. The set of grid cells whose water flow direction converges to the same drainage outlet is defined as a catchment area, and the location of roadside ditches and drainage ditches is used as the constraint condition of the area boundary. Obtain the cross slope and longitudinal slope of each road, and correct the direction of surface water flow at each point on the road surface according to the combined direction of the cross slope and longitudinal slope, so that the direction of surface water flow in the road area is guided from the cross slope of the road to the side ditches or rainwater inlets on both sides of the road.

[0010] Furthermore, the comprehensive runoff coefficient is calculated as follows: The ratio of the area of ​​each type of underlying surface in each catchment area to the total area of ​​that catchment area is weighted and summed with the corresponding runoff coefficient. The underlying surface types include road surfaces, building roofs, green spaces, and bare soil. The surface runoff parameter data include the area of ​​each catchment area, the comprehensive runoff coefficient, the runoff path length, the average runoff time, and the number and location of storm drains in each catchment area.

[0011] Furthermore, the calculation of surface runoff for each catchment area at each time step includes: Rainfall intensity is uniformly converted into water volume per unit area per unit time, and the area of ​​each catchment zone is uniformly converted into square meters; the surface runoff of the catchment zone within each time step is obtained by multiplying the rainfall intensity within each time step by the area of ​​the catchment zone and the comprehensive runoff coefficient. The duration of the time step is no greater than the time interval between adjacent data points on the rainfall intensity variation curve; the time delay of the surface runoff reaching the corresponding storm inlet is calculated based on the runoff path length and average runoff time of each runoff zone, and the inflow sequence of each storm inlet within each time step is generated.

[0012] Furthermore, the hydraulic-hydrological coupling calculation includes: When the calculated water level of a node exceeds the ground elevation corresponding to the node within a certain time step, it is determined that the node has overflowed. The overflow amount of the node is the positive part of the difference between the total flow into the node within the time step and the sum of the full flow capacity of each downstream pipe section connected to the node under the current water level conditions. When the difference is negative or zero, the overflow amount is zero. The overflow is distributed to the surface at the location of the node, and the diffusion process of the surface water flow is solved using a two-dimensional shallow water equation to obtain the distribution range of the overflow water on the surface and the water depth at each location. The simulation results of the waterlogging in the area include the distribution of surface water depth, waterlogging range, flow rate of each pipe section, water level of each node, and the evolution sequence of water depth and waterlogging range over time at each time step.

[0013] Furthermore, the flow capacity utilization rate is the ratio of the maximum flow rate of the pipe section over all time steps during the simulation to the theoretical flow capacity of the pipe section under full flow conditions. The theoretical flow capacity is calculated using the Manning formula based on pipe diameter, pipe slope, and pipe roughness coefficient; pipe sections with flow capacity utilization exceeding a preset utilization threshold are marked as pipe sections with insufficient flow capacity. Based on the pipe slope and pipe roughness coefficient of the pipe section with insufficient flow capacity, under the condition that the pipe slope and pipe material remain unchanged, the Manning formula is used to back-calculate the minimum pipe diameter value corresponding to the full flow capacity when it is not lower than the design drainage flow rate, and the pipe diameter upgrade parameters of the pipe section are generated.

[0014] Furthermore, after generating the pipeline renovation plan, the process also includes: updating the pipe diameter upgrade parameters of each pipe segment and the renovation measure parameters of each node in the pipeline renovation plan to the integrated spatial model of pipeline network and terrain, generating the integrated spatial model of pipeline network and terrain after renovation, re-performing the hydraulic and hydrological coupling calculation based on the integrated spatial model of pipeline network and terrain and the same design rainfall process data, generating the simulation results of waterlogging in the area after renovation, comparing the simulation results of waterlogging in the area after renovation with the simulation results of waterlogging in the area before renovation, extracting the changes in water depth, water area and water duration in each area after renovation, and generating renovation effect simulation data; If there are still areas in the pre-simulation data of the renovation effect that have water depth exceeding the preset water depth threshold, the renovation measures parameters of the corresponding areas in the pipeline renovation plan will be adjusted and the effect simulation process will be performed again until the water depth of all areas does not exceed the preset water depth threshold or the preset iteration number limit is reached.

[0015] This invention provides a 3D digital modeling system for underground pipelines based on GIS and BIM, comprising: The spatial data base construction module is used to acquire BIM parameter data and geospatial data of road projects in the target area, and to perform unified processing and overlay registration of the BIM parameter data of road projects and geospatial data to generate an integrated spatial data base of roads, buildings and terrain. The pipeline spatial model construction module is used to acquire BIM parameter data of underground pipelines in the target area, map the pipeline BIM parameter data to a unified spatial coordinate reference, generate a pipeline spatial topology map, and spatially overlay the pipeline spatial topology map with the terrain surface to generate an integrated spatial model of pipeline and terrain. The surface runoff parameter generation module is used to divide the surface of the target area into runoff zones based on the integrated spatial data base of roads, buildings and terrain and the integrated spatial model of pipeline network and terrain, calculate the comprehensive runoff coefficient of each runoff zone, establish the correspondence between each runoff zone and rainwater inlet, and generate surface runoff parameter data. The hydraulic-hydrological coupling calculation module is used to calculate the surface runoff of each catchment area at each time step based on the design rainfall process data and the surface runoff parameter data. The inflow sequence of each rainwater inlet is used as the boundary condition. Based on the integrated spatial model of pipe network and topography, the hydraulic-hydrological coupling calculation is performed using the pipe network unsteady flow solution method based on the Saint-Venant equations to generate the simulation results of regional waterlogging. The pipeline renovation scheme generation module is used to calculate the flow capacity utilization rate of each pipe section based on the flood simulation results of the area, mark the pipe sections with insufficient flow capacity and overflow nodes, determine the cause of overflow and generate renovation measures parameters, and summarize and generate a pipeline renovation scheme.

[0016] This invention integrates BIM parameter data from road engineering and pipeline engineering with GIS geospatial data under a unified spatial coordinate reference, generating an integrated spatial data base and an integrated spatial model of pipelines and terrain. This solves the technical problem of spatial deviations in input data for urban flooding analysis caused by incompatible multi-source data formats and inconsistent spatial coordinates. It achieves the technical effect of unified management of road elevation, pipeline spatial topology, and terrain runoff characteristics within the same data system. Furthermore, it uses hydraulic-hydrological coupling calculations to integrate surface runoff generation, stormwater inflow, pipeline drainage, and surface water diffusion. By incorporating the same calculation process, the technical problem of traditional methods being unable to extrapolate the evolution of urban flooding at the regional scale has been solved. This has achieved the technical effect of completing the simulation of the entire process from rainfall to water accumulation at the regional scale, supporting the spatial location of urban flooding risk points and tracing the causes of water accumulation. By automatically identifying pipe sections with insufficient flow capacity and overflow nodes and generating parameters for renovation measures, combined with a closed-loop processing process that simulates the renovation effect, the technical problem of traditional pipe network renovation schemes relying on manual experience and being unable to quantitatively evaluate the drainage effect before implementation has been solved. This has achieved the technical effect of transforming the formulation of pipe network renovation schemes from experience-driven to simulation data-driven. Attached Figure Description

[0017] Figure 1 This is a flowchart of the three-dimensional digital modeling method for underground pipelines based on GIS and BIM provided in the embodiments of the present invention; Figure 2 This is a schematic diagram comparing the area of ​​each catchment zone with the comprehensive runoff coefficient provided in the embodiments of the present invention; Figure 3 This is a schematic diagram of the average runoff time and the number of rainwater inlets for each catchment area provided in the embodiments of the present invention; Figure 4 This is a schematic diagram comparing the full-flow capacity of a typical pipe section with the simulated maximum flow rate provided in the embodiments of the present invention; Figure 5 This is a schematic diagram illustrating the utilization rate of the flow capacity of a typical pipe section provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a design rainfall process (120 minutes, once every 5 years) provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the time-series changes in water level at key nodes (comparison before and after modification) provided in an embodiment of the present invention; Figure 8 This is a schematic diagram comparing the number of triangular facets before and after the lightweighting process of the three-dimensional model provided in this embodiment of the invention. Detailed Implementation

[0018] In the field of urban flood control, traditional flood analysis methods typically manage and process road engineering data, underground pipe network data, and geospatial data independently. Road vertical design parameters, pipe network drainage capacity parameters, and topographic runoff characteristics are stored in different data systems, lacking a unified spatial benchmark and topological correlation. This leads to the following technical problems: First, incompatible multi-source data formats and inconsistent spatial coordinates prevent accurate matching of roads, pipe networks, and terrain within the same analysis scenario, resulting in spatial bias in the input data for flood simulation. Second, traditional flood analysis only calculates drainage capacity for single points or pipe sections, failing to perform a coupled extrapolation of the entire process from surface runoff, storm drain inflow, pipe network drainage, to water accumulation at a regional scale, leading to vague positioning of flood risk points and difficulty in tracing the causes of water accumulation. Third, pipe network defect identification and renovation plan formulation rely on manual inspection and experience-based judgment; renovation plans cannot be pre-implemented with effect simulations, easily resulting in insufficient targeted renovations and substandard drainage effects. Therefore, a method is needed that can deeply integrate road BIM engineering parameters, pipeline BIM engineering parameters and GIS geospatial data, and complete the whole process simulation analysis of regional waterlogging and intelligent pipeline transformation on a unified data platform.

[0019] According to an embodiment of this invention, this invention provides a method for three-dimensional digital modeling of underground pipelines based on GIS and BIM. It should be understood that the computer equipment executing this method for three-dimensional digital modeling of underground pipelines based on GIS and BIM is configured with at least a BIM parametric modeling processing module, a GIS geospatial data processing module, a hydraulic-hydrological coupled calculation engine, and a data storage unit. The BIM parametric modeling processing module is used to parse and manage engineering-level parametric data of roads and pipeline networks; the GIS geospatial data processing module is used to load and process spatial data such as topographic DEMs and geographic elevations; and the hydraulic-hydrological coupled calculation engine is used to perform joint simulation calculations of surface runoff and pipeline drainage.

[0020] At least one embodiment of the present invention discloses a three-dimensional digital modeling method for underground pipelines based on GIS and BIM, such as... Figure 1 As shown, it includes the following steps: Step 1: Obtain BIM parameter data and geospatial data for road engineering, and generate an integrated spatial data base for roads, buildings, and terrain; Based on the BIM parametric modeling processing module, BIM parameter data for road engineering within the target area is acquired. This data includes road elevation, cross-sectional geometric parameters, longitudinal slope parameters, ditch section parameters, and drainage ditch location coordinates. Simultaneously, based on the GIS geospatial data processing module, topographic DEM data, geographic elevation data, and building outline and height data for the target area are acquired. The spatial coordinates in the road engineering BIM parameter data and the spatial coordinates in the geospatial data are unified under a common reference. A spatial matching algorithm is then used to overlay and register the 3D linear model of the road engineering, the 3D outline model of the buildings, and the 3D terrain surface, generating an integrated spatial data base for roads, buildings, and terrain. This integrated spatial data base stores the geometric parameters and spatial topological relationships of roads, buildings, and terrain using a unified spatial coordinate reference.

[0021] It should be noted that the above spatial matching algorithm uses the geodetic coordinate system in the geospatial data as the reference coordinate system. After mapping the local engineering coordinates of each element in the road engineering BIM parameter data to the reference coordinate system through the coordinate transformation matrix, the terrain surface is trimmed and fitted according to the three-dimensional line shape of the road centerline. At the same time, the building outline is projected onto the terrain surface to obtain its bottom elevation, thereby completing the accurate positioning of the three types of elements in the same coordinate space.

[0022] It should be noted that the cross-sectional geometric parameters in the above-mentioned road engineering BIM parameter data include the width of the carriageway, the width of the sidewalk, the width of the shoulder, the cross slope of the road crown, and the bottom width and depth of the side ditch section. The above-mentioned longitudinal slope parameters include the starting and ending station numbers, longitudinal slope values, and vertical curve radii of each vertical curve segment.

[0023] In this embodiment of the application, in order to enable the integrated spatial data base of roads, buildings and terrain to respond to dynamic adjustments during the design phase, the following processing is also included in step 1: when the vertical design parameters of the road, the building layout or the terrain data change, the changed parameter data is obtained, and the geometric parameters and spatial topological relationships of the corresponding elements in the integrated spatial data base of roads, buildings and terrain are incrementally updated based on the changed parameter data to generate an updated integrated spatial data base of roads, buildings and terrain, thereby avoiding deviations in subsequent analysis results due to inconsistencies between the integrated spatial data base of roads, buildings and terrain and the actual design state.

[0024] Step 2: Obtain BIM parameter data for the pipeline network project and generate an integrated spatial model of the pipeline network and terrain; Based on the BIM parametric modeling processing module, BIM parameter data of the underground pipe network within the target area is acquired. This data includes the pipe diameter, pipe material, pipe slope, and burial depth of each pipe segment, as well as the diameter, depth, and bottom elevation of each manhole, the location coordinates and type parameters of each valve well, and the location coordinates and connecting pipe parameters of each storm drain inlet. Using the terrain surface elevation data from the integrated spatial data base of roads, buildings, and topography, the spatial coordinates of each node and pipe segment in the pipe network BIM parameter data are mapped to a unified spatial coordinate reference. Based on the upstream and downstream connection relationships between nodes in the pipe network, a pipe network spatial topology map is generated. This map records the connection node identifiers, flow directions, and the number of incoming and outgoing pipe segments for each node. The pipe network spatial topology map is then spatially overlaid with the terrain surface to generate an integrated spatial model of the pipe network and topography.

[0025] It should be noted that the sources of the above-mentioned pipeline network BIM parameter data include pipeline data in at least one of the following data formats: geophysical pipeline data in table format, database format, SHP format GIS data, and CAD format design pipeline results. After the pipeline data in each of the above formats is parsed according to pipeline professional rules, the attribute parameters and coordinate information of each pipe segment and node are extracted and converted into a unified pipeline network BIM parameter data structure.

[0026] It should be noted that the flow direction in the above pipeline spatial topology diagram is determined based on the difference in pipe bottom elevation between the start and end points of each pipe segment. The end with the higher pipe bottom elevation is the upstream node, and the end with the lower pipe bottom elevation is the downstream node. When the slope of the pipe segment is zero, the flow direction is assigned according to the design document.

[0027] In this embodiment of the application, in order to improve the spatial consistency between the integrated spatial model of pipeline network and terrain and the actual project, the following processing is also included when generating the integrated spatial model of pipeline network and terrain: generating a three-dimensional solid geometric model of each pipe segment based on the pipe diameter and pipe material parameters, generating a three-dimensional solid geometric model of each manhole based on the manhole diameter and manhole depth parameters, assembling the three-dimensional solid geometric models of each pipe segment and each manhole according to the connection relationship in the pipeline network spatial topology diagram, and spatially superimposing it with the terrain surface, thereby completely restoring the geometric shape and spatial layout of the pipeline network in three-dimensional space.

[0028] Step 3: Based on the integrated spatial data base of roads, buildings, and terrain, and the integrated spatial model of pipelines and terrain, obtain surface runoff parameter data; Based on topographic DEM data and road elevation data from the integrated spatial data base of roads, buildings, and terrain, the surface of the target area is divided into catchment zones, generating the boundary range and area parameters of each catchment zone. The specific process of catchment zone division is as follows: based on the elevation value of each raster cell in the topographic DEM data, the surface water flow direction of each raster cell is calculated. The set of raster cells whose water flow direction converges to the same drainage outlet is defined as a catchment zone. At the same time, the location of roadside ditches and drainage ditches is used as the constraint condition for the zone boundary.

[0029] Based on the boundary range of each catchment area, the distribution data of underlying surface types within each catchment area are obtained. These underlying surface types include road surfaces, building roofs, green spaces, and bare soil. The comprehensive runoff coefficient of each catchment area is calculated based on the runoff coefficient corresponding to each underlying surface type. Based on the boundary range and topographic slope of each catchment area, the runoff path length and average runoff time of each catchment area are calculated. Based on the location coordinates of each stormwater inlet in the integrated spatial model of the pipe network and topography, each stormwater inlet is assigned to its corresponding catchment area, establishing the correspondence between each catchment area and its contained stormwater inlets, generating surface runoff parameter data. The surface runoff parameter data includes the area, comprehensive runoff coefficient, runoff path length, average runoff time of each catchment area, and the number and location of stormwater inlets within each catchment area.

[0030] It should be noted that the above-mentioned comprehensive runoff coefficient is calculated by weighting and summing the area proportion of various underlying surfaces within each catchment area with their corresponding runoff coefficients. ,in This is the comprehensive runoff coefficient of the catchment area. For the first The ratio of the area of ​​the underlying surface to the total area of ​​the catchment area. For the first The runoff coefficient corresponding to the underlying surface type The number of underlying surface types. This is an index for the underlying surface type.

[0031] In this embodiment of the application, in order to make the zoning results of the catchment area more accurately reflect the guiding effect of road engineering on surface runoff, the following processing is also included in the zoning process: obtaining the cross slope and longitudinal slope of each road in the integrated spatial data base of roads, buildings and terrain, and correcting the surface water flow direction at each point on the road surface according to the combined direction of the cross slope and longitudinal slope, so that the surface water flow direction in the road area is guided by the cross slope of the road to the side ditches or storm drains on both sides of the road, rather than being calculated solely based on the raster elevation of the terrain DEM data, thereby improving the accuracy of the zoning of the road area catchment area.

[0032] Step 4: Based on surface runoff parameter data and an integrated spatial model of pipe network and topography, perform hydraulic and hydrological coupled calculations to generate simulation results of urban flooding in the area; Acquire the design rainfall process data for the target area, which includes rainfall duration, rainfall intensity variation curves over time, and rainfall return period. Before performing hydraulic-hydrological coupling calculations, preprocess the input parameters with inconsistent dimensions in the surface runoff parameter data and the design rainfall process data: convert the rainfall intensity to water volume per unit area per unit time (unit: ). The area of ​​each catchment zone is uniformly converted to square meters to ensure that the dimensions of each parameter are consistent in the subsequent production flow calculation.

[0033] Based on preprocessed design rainfall event data and surface runoff parameter data, surface runoff for each catchment area was calculated at each time step. The surface runoff was calculated by multiplying the rainfall intensity at each time step by the area and comprehensive runoff coefficient of the catchment area. ,in For this catchment area in the 1st Surface runoff over a time step (in units of...) ), For the first Preprocessed rainfall intensity within a time step (unit: ), The area of ​​the catchment zone (in units of) ), This is the comprehensive runoff coefficient (dimensionless) for this catchment area. This is the index for the time step.

[0034] Furthermore, the range of values ​​for the duration of the aforementioned time step is as follows: to The specific value is determined based on the time resolution of the rainfall intensity variation curve in the designed rainfall process data. That is, the length of the time step is not greater than the time interval between adjacent data points of the rainfall intensity variation curve, so as to ensure the rainfall intensity within each time step. It can be considered a constant, thus ensuring the time accuracy of the production flow calculation.

[0035] Based on the runoff path length and average runoff time of each catchment area, the time delay of surface runoff reaching the corresponding stormwater inlet in each catchment area is calculated, generating the inflow sequence of each stormwater inlet within each time step. The inflow sequence of each stormwater inlet is used as the boundary condition input for the pipe network drainage calculation. Based on the pipe diameter, slope, and roughness coefficient of each pipe segment in the integrated spatial model of the pipe network and topography, as well as the connection relationships and flow directions in the pipe network spatial topology map, the unsteady flow solution method based on the Saint-Venant equations is used to solve the flow rate of each pipe segment and the water level of each node within each time step. The input of this unsteady flow solution method based on the Saint-Venant equations are the inflow sequence of each stormwater inlet, the pipe diameter, slope, and roughness coefficient of each pipe segment, and the connection relationships and flow directions in the pipe network spatial topology map. The output is the time series data of the flow rate of each pipe segment and the water level of each node within each time step. The Saint-Venant equations include the continuity equation and the momentum equation. The continuity equation is... The momentum equation is ,in The cross-sectional area of ​​the pipeline through which water flows. For the flow rate of the pipe section, The lateral inflow rate per unit length. It is the acceleration due to gravity. For water level, For friction slope, This represents the distance along the direction of the pipeline. For time.

[0036] Furthermore, the aforementioned friction slope The flow rate, cross-sectional area, and hydraulic radius of the pipe section are determined according to Manning's formula. Specifically, ,in For pipe roughness coefficient, The hydraulic radius, i.e., the ratio of the cross-sectional area of ​​the water passage to the wetted perimeter, is the frictional slope. The hydraulic parameters are updated synchronously with each time step during the solution of the momentum equation.

[0037] When the calculated water level at a node exceeds the corresponding ground elevation within a certain time step, overflow is determined to have occurred at that node. The overflow volume at that node is calculated and distributed to the surface at the node's location. Based on the elevation values ​​of each raster cell in the terrain DEM data, a two-dimensional shallow water equation is used to solve the diffusion process of surface water flow, obtaining the distribution range of overflow water on the surface and the water depth at each location. This generates the water depth and water area for each surface region within that time step. The calculation results for all time steps are summarized to generate the regional flooding simulation results. These results include the surface water depth distribution, water area, flow rate of each pipe section, and water level at each node for each time step, as well as the evolution sequence of water depth and water area over time.

[0038] Furthermore, the above overflow is calculated as follows: when a node is in the... Calculated water level within a time step Exceeding the ground elevation corresponding to this node At that time, the overflow of this node Determined by the continuity equation, the flow rate is the difference between the total flow rate flowing into the node within a given time step and the maximum overflow capacity of the pipe segment connected to the node. The total flow rate flowing into the node originates from the sum of the inflow rate from the upstream pipe segment and the inflow rate from the storm drain inlet. The maximum overflow capacity of the pipe segment connected to the node is the sum of the full-flow capacity of each downstream pipe segment under the current water level conditions. The overflow rate is... This refers to the positive part of the above difference. When the difference is negative or zero, the overflow is zero.

[0039] In this embodiment of the application, in order to analyze the differences in the impact of different rainfall scenarios on regional flooding, the following processing is also included in step 4: acquiring design rainfall process data corresponding to multiple different rainfall return periods, performing the above-mentioned hydraulic-hydrological coupling calculation on each rainfall return period, generating regional flooding simulation results corresponding to each rainfall return period, comparing the regional flooding simulation results of each rainfall return period, extracting the maximum water accumulation depth, maximum water accumulation area and water accumulation duration under each rainfall return period, and generating multi-scenario flooding comparative analysis data.

[0040] In this embodiment of the application, in order to accurately locate the flood-prone areas within the area, after generating the flood simulation results of the area, the following processing is also included: based on the maximum water accumulation depth of each surface area in the flood simulation results of the area, areas with a maximum water accumulation depth exceeding a preset water accumulation depth threshold are marked as flood-prone areas, the location coordinates, maximum water accumulation depth, water accumulation area and water accumulation duration of each flood-prone area are extracted, and the upstream pipeline nodes and pipe segments corresponding to each flood-prone area are traced based on the pipeline network spatial topology map to generate flood-prone area identification results. The flood-prone area identification results include the spatial location of each flood-prone area, water accumulation characteristic parameters and the identification of the associated pipeline nodes and pipe segments.

[0041] Furthermore, the aforementioned preset water depth threshold is determined based on the engineering criteria for assessing the impact of urban road water accumulation on pedestrian and vehicle traffic. For the assessment of pedestrian traffic impact, the preset water depth threshold is set to... For determining the impact on vehicle traffic, the preset water depth threshold is set to... When marking flood-prone areas, the corresponding preset water depth threshold is selected for comparison based on the analysis target.

[0042] Step 5: Based on the simulation results of local flooding and the integrated spatial model of pipe network and terrain, identify pipe network defects and generate pipe network renovation plans; Based on the flow rate of each pipe segment and the water level data of each node in the regional flooding simulation results, the flow capacity of each pipe segment in the pipe network is evaluated, and the flow capacity utilization rate of each pipe segment is calculated. The flow capacity utilization rate is the ratio of the maximum flow rate of the pipe segment during the simulation to the theoretical flow capacity of the pipe segment when it is at full flow. ,in To optimize the utilization rate of overcurrent capacity, This represents the maximum flow rate of this pipe section during the simulation. This represents the theoretical flow capacity of the pipe section under full-flow conditions, calculated based on pipe diameter, slope, and roughness coefficient. Because... and Same dimensions This is a dimensionless ratio and can be directly used for threshold comparison. Pipe sections with flow capacity utilization exceeding a preset utilization threshold are marked as pipe sections with insufficient flow capacity.

[0043] Furthermore, the above This represents the maximum flow rate of the pipe section over all simulation time steps, i.e., the flow rate over each time step included in the regional flooding simulation results. The maximum value is taken from the corresponding pipe section flow rate time series data to reflect the maximum hydraulic load that the pipe section bears throughout the entire rainfall process.

[0044] Furthermore, the above The calculation uses the Manning formula, that is... ,in For pipe roughness coefficient, The full-flow cross-sectional area of ​​the pipe. The hydraulic radius under full flow conditions. For pipe slope, all the above parameters are directly taken from the attribute values ​​of the corresponding pipe segments in the pipe network BIM parameter data.

[0045] Furthermore, the aforementioned preset utilization rate threshold is determined based on the limit requirements for pipe filling degree in the urban drainage pipe network design code. For rainwater pipes, the preset utilization rate threshold is taken as... That is, when the maximum flow rate of a pipe section reaches or exceeds its theoretical full-flow capacity, the pipe section is deemed to have insufficient flow capacity. In engineering practice, the preset utilization rate threshold can also be set to no greater than the pipe fullness limit specified in the design documents. The value is set to allow for a safety margin in drainage.

[0046] Meanwhile, based on the relationship between the maximum water level of each node and the ground elevation of that node during the simulation process, nodes whose maximum water level exceeds the ground elevation are marked as overflow nodes.

[0047] Based on the pipe diameter, slope parameters, and design drainage flow rate of the catchment area where the insufficient flow capacity pipe section is located, the minimum pipe diameter required to meet the design drainage flow rate is calculated. The minimum pipe diameter is calculated using the Manning formula, with the pipe slope, pipe material roughness coefficient, and design drainage flow rate as inputs. Under the condition that the pipe slope and pipe material remain unchanged, the minimum pipe diameter value corresponding to ensuring that the full-flow capacity is not less than the design drainage flow rate is calculated. The Manning formula is as follows: ,in For pipe roughness coefficient, The full-flow cross-sectional area of ​​the pipe. For hydraulic radius, Generate pipe diameter upgrade parameters for this pipe section based on the pipe slope.

[0048] Furthermore, the back-calculation process for the minimum pipe diameter is as follows: For a circular cross-section pipe, the full-flow cross-sectional area... hydraulic radius ,in Let be the inner diameter of the pipe. Substituting the above relationship into Manning's formula, we obtain: The equation with the only unknown quantity is given by the pipe slope. and roughness coefficient Under the condition of keeping the design drainage flow rate constant, the equation is numerically solved with the design drainage flow rate as the objective value, and the results are... The minimum required value is the minimum pipe diameter upgrade value for that pipe section.

[0049] Based on the overflow volume of an overflow node and the flow capacity utilization rate of the upstream merging pipe section, the cause of the overflow is determined: if the flow capacity utilization rate of the upstream pipe section exceeds a preset threshold, the cause of the overflow at that overflow node is marked as insufficient flow capacity of the upstream pipe section; if the flow capacity utilization rate of the upstream pipe section does not exceed the preset threshold but the overflow node still overflows, the cause of the overflow at that overflow node is marked as a bottleneck at the node's confluence. For each overflow node's cause, corresponding modification measures parameters are generated. These measures include at least one of the following: upgrading the pipe diameter of the upstream pipe section, modifying the node structure, and adding overflow storage facilities. The pipe diameter upgrade parameters for all pipe sections with insufficient flow capacity and the modification measures parameters for all overflow nodes are summarized to generate a pipeline network modification plan.

[0050] In this embodiment of the application, in order to verify the drainage effect of the pipeline renovation scheme before its implementation, the following processing is included after generating the pipeline renovation scheme: updating the pipe diameter upgrade parameters of each pipe section and the renovation measure parameters of each node in the pipeline renovation scheme to the integrated spatial model of pipeline network and terrain, generating the integrated spatial model of pipeline network and terrain after renovation; based on the integrated spatial model of pipeline network and terrain after renovation and the same design rainfall process data, re-executing the hydraulic and hydrological coupling calculation in step 4 to generate the simulation results of waterlogging in the area after renovation; comparing the simulation results of waterlogging in the area after renovation with the simulation results of waterlogging in the area before renovation, extracting the changes in water depth, water area and water duration of each flood-prone area after renovation, and generating the renovation effect prediction data. If there are still areas in the pre-simulation data of the renovation effect that have water depth exceeding the preset water depth threshold, the renovation measures parameters of the corresponding areas in the pipeline renovation plan will be adjusted, the adjusted pipeline renovation plan will be regenerated, and the above effect simulation process will be executed again until the water depth of all areas does not exceed the preset water depth threshold or the preset iteration limit is reached, forming a closed-loop processing flow of defect identification, plan generation and effect simulation.

[0051] Step 6: Perform lightweight processing on the integrated spatial data base of roads, buildings, and terrain, the integrated spatial model of pipelines and terrain, and the simulation results of urban flooding in the area to generate multi-source data fusion display data; The system acquires 3D model data of roads from an integrated spatial data base encompassing roads, buildings, and terrain; 3D model data of pipe networks from an integrated spatial model encompassing pipe networks and terrain; and time-series data of water depth distribution from regional flooding simulation results. This 3D model data undergoes compression processing, including triangle simplification and texture map resolution downsampling, generating lightweight 3D model data. Triangle simplification reduces the number of triangles in the 3D model while maintaining the overall geometric contour, thereby reducing the storage size and rendering computational load. The lightweight 3D model data is then spatially overlaid with GIS geospatial base map data. Layers are registered according to a unified spatial coordinate benchmark, and the time-series data of water depth distribution is overlaid onto the GIS geospatial base map data as a time-series layer, generating multi-source data fusion display data. This multi-source data fusion display data supports integrated visualization loading of road, pipe network, and flooding distribution, interactive attribute queries, and dynamic playback of the flooding evolution process on display terminals.

[0052] In this embodiment of the application, in order to support the synchronous update of pipeline network analysis data between the cloud platform and the local BIM model, the following processing is also included in step 6: uploading the pipeline network attribute information and the spatial topology relationship in the integrated spatial model of pipeline network and terrain to the cloud analysis platform, performing pipeline network collision detection processing on the cloud analysis platform, generating collision detection result data, sending the collision detection result data back to the local BIM model, and automatically updating the collision marker attributes of the corresponding pipe segments and nodes in the local BIM model, so as to realize bidirectional data synchronization between the cloud analysis results and the local BIM model.

[0053] This implementation method integrates road engineering BIM parameter data, pipeline engineering BIM parameter data, and GIS geospatial data under a unified spatial coordinate reference to generate an integrated spatial data base for roads, buildings, and terrain, as well as an integrated spatial model for pipelines and terrain. This allows road elevations, pipeline spatial topology, and terrain confluence characteristics to be managed within the same data system, thus overcoming the problems of incompatible multi-source data formats and inconsistent spatial coordinates that cause input data deviations in urban flooding analysis in traditional methods.

[0054] This implementation method is based on an integrated spatial data platform of roads, buildings, and topography. Through hydraulic and hydrological coupling calculations, it incorporates surface runoff generation, stormwater inflow, pipe network drainage, and surface water diffusion into the same calculation process for solution. It completes the simulation of the entire process from rainfall to water accumulation at the regional scale. Therefore, it overcomes the limitations of traditional methods that can only perform drainage capacity calculations for single points or single pipe sections and cannot extrapolate the evolution of urban flooding at the regional scale. This provides data support for the spatial location of urban flooding risk points and the tracing of the causes of water accumulation.

[0055] This implementation method automatically identifies pipe sections with insufficient flow capacity and overflow nodes based on the flow rate and water level data of each pipe section in the regional flood simulation results. It also generates corresponding modification measures parameters for different overflow causes. At the same time, it re-executes simulation calculations to preview the modification effect by updating the pipeline network modification plan to the integrated spatial model of pipeline network and terrain. Therefore, it overcomes the problem that traditional pipeline network modification plans rely on manual experience and cannot quantitatively evaluate the flood drainage effect before implementation, and transforms the formulation of pipeline network modification plans from experience-driven to simulation data-driven.

[0056] The following is an example of an application of the present invention, such as... Figure 2-8 As shown, the implementation process is as follows: After completing the road and pipeline construction design, a newly developed area in a city (hereinafter referred to as "Planning Area A") needs to undergo a full-process simulation assessment of its drainage capacity and flood risk before completion, and develop renovation plans for the weak links in the pipeline network exposed in the simulation. Planning Area A covers approximately 18.6 hectares and includes three main roads (Road A, Road B, and Road C), one residential cluster (Cluster A), and several public green spaces. The underground stormwater pipeline network consists of 31 pipe sections, 28 inspection wells, and 42 stormwater inlets, with the final drainage outlet connected to the municipal main pipeline on the east side of the area. The terrain of the area slopes from west to east, with an elevation difference of approximately 2.8 meters. The design uses a 5-year return period for rainfall as the check condition, with a rainfall duration of 120 minutes, and the design rainfall process is generated using the local storm intensity formula.

[0057] For planning area A, engineering parameter data for roads A, B, and C were extracted from the road construction drawing BIM model. Simultaneously, 1m resolution topographic DEM data and building outline vector data for the area were obtained from a surveying unit. The local engineering coordinate system of the road BIM model (with the origin at chainage K0+000 of road A) was mapped to the urban coordinate system (CGCS2000) using a coordinate transformation matrix, and spatially overlaid and registered with the topographic DEM data to generate an integrated spatial data base for roads, buildings, and topography.

[0058] Table 1. Partial BIM Parameter Data for Road Engineering

[0059] After spatial matching was completed, the maximum deviation between the three-dimensional alignment of the centerline of road A and the surface of the terrain DEM was 0.03m, which met the spatial accuracy requirements of waterlogging analysis. The integrated spatial data base of road, building and terrain was officially entered into the database.

[0060] The attribute parameters of all pipe segments and nodes in planning area A are extracted from the pipeline network design BIM model (IFC format). Existing pipeline parameters obtained from geophysical pipeline data tables are also supplemented and uniformly converted into a pipeline network BIM parameter data structure. The flow direction is determined based on the elevation difference between the start and end points of each pipe segment, and a pipeline network spatial topology map is constructed. This map is then overlaid with the terrain surface to generate an integrated spatial model of the pipeline network and terrain. Taking a typical pipe segment in the core catchment area of ​​the region as an example, the key pipe segment parameters are as follows.

[0061] Table 2 Typical pipe sections and node parameters

[0062] The pipeline network topology diagram shows that pipe sections P07, P12, and P18 all converge at well number J28, the outlet node on the east side of the area. Among them, P18 is the main water intake pipe section, which receives the water from the upstream branch pipes P07 and P12.

[0063] Based on the topographic DEM grid elevation, the flow direction of each grid was calculated. Simultaneously, the cross slope (1.5%–2.0%) and longitudinal slope of roads A, B, and C were incorporated for correction, directing road surface water flow towards the side ditches and storm drains. Ultimately, planning area A was divided into six catchment zones (Z1–Z6). Within each zone, the area ratio of various underlying surfaces was statistically analyzed based on building outlines, road boundaries, and green space boundaries, and the comprehensive runoff coefficient was calculated.

[0064] Taking catchment zone Z3 as an example, the total area of ​​this zone is The underlying surface is composed as follows: road surface accounts for 0.32%, corresponding to a runoff coefficient of 0.90; building roof accounts for 0.28%, corresponding to a runoff coefficient of 0.92; green space accounts for 0.25%, corresponding to a runoff coefficient of 0.15; and bare soil accounts for 0.15%, corresponding to a runoff coefficient of 0.30.

[0065] The comprehensive runoff coefficient is calculated as follows:

[0066]

[0067] The surface runoff parameter data for each runoff zone are summarized below.

[0068] Table 3. Surface runoff parameters for each catchment area

[0069] A 120-minute design rainfall event was generated using the local 5-year return period rainstorm intensity formula, with a time step of 60 seconds. The peak rainfall occurred at the 42nd minute, and the peak rainfall intensity was [value missing]. (Equivalent to 85.7 mm / h). The dimensions were preprocessed to unify the area unit of each catchment zone to m. 2 The unit for rainfall intensity is uniformly set to .

[0070] Taking the surface runoff calculation of zone Z3 at the peak rainfall time step (step 42) as an example:

[0071] Considering the average confluence time of 10.4 minutes (approximately 11 time steps) for zone Z3, the flow rate reaches the stormwater inlet group corresponding to well number J11 at step 53, serving as the input for the boundary conditions in the pipe network calculation. Based on the Saint-Venant equations, unsteady flow solutions are performed for the flow rates of each pipe segment and the water levels at each node. Taking pipe segment P12 as an example (at step 53, the current flow rate...),... Full flow cross-sectional area hydraulic radius The friction slope is calculated as follows:

[0072] After the simulation calculations were completed, at the 58th minute, the water level at well J11 reached a ground elevation of 19.23m, resulting in overflow; at the 62nd minute, the water level at well J17 reached a ground elevation of 18.87m, also resulting in overflow. After diffusion calculations using the two-dimensional shallow water equation, the overflow water volume formed a waterlogged area with a maximum depth of 0.38m (approximately 1420m²) at the low-lying area of ​​the intersection of Road B and Road C. 2 A waterlogged area with a maximum depth of 0.22m (approximately 680m²) was formed in the green space on the west side of Group A. 2 ).

[0073] The flood-prone areas were marked using the vehicle traffic impact assessment standard (water depth threshold of 0.30m). The waterlogged area at the intersection of Road B and Road C was marked as flood-prone area EZ-01, with the associated pipe sections being P12 and P18, and the associated nodes being well numbers J11 and J17.

[0074] Based on the flow rate time series data of each pipe segment in the simulation results, the flow capacity utilization rate of each pipe segment is calculated. Taking pipe segments P12 and P18 as examples, the theoretical full-flow capacity is first calculated using the Manning formula.

[0075] For pipe section P12 (diameter 0.5m, slope 0.0028, roughness coefficient 0.013):

[0076]

[0077] For pipe section P18 (diameter 0.8m, slope 0.0015, roughness coefficient 0.013):

[0078]

[0079] The flow capacity assessment results for each typical pipe section are as follows.

[0080] Table 4. Flow capacity assessment results for typical pipe sections

[0081] Flow capacity utilization rate of pipe section P12 If the current exceeds the threshold of 1.0, the pipe section is determined to have insufficient flow capacity; pipe section P18 It also exceeds the threshold.

[0082] Overflow occurred at wells J11 and J17. Source analysis showed that the flow capacity utilization rate of the upstream merging pipe sections (P12, P18) both exceeded 1.0, and the cause of the overflow was marked as "insufficient flow capacity of the upstream pipe section".

[0083] For pipe section P12, the design drainage flow rate for zone Z3 is 0.312 m³ / s. 3 With / s as the target value, and under the condition that the slope is 0.0028 and the roughness coefficient is 0.013 constant, the Manning formula is inversely calculated: , Substituting the values, the minimum pipe diameter upgrade value is found to be 0.65m. Taking the standard pipe diameter specification, the pipe diameter upgrade parameter for pipe section P12 is determined to be 700mm. For pipe section P18, a similar reverse calculation yields a minimum pipe diameter upgrade value of approximately 0.87m, and the pipe diameter upgrade parameter is determined to be 1000mm.

[0084] The pipeline renovation plans are summarized below.

[0085] Table 5 Summary of parameters for pipeline renovation scheme

[0086] The aforementioned modification parameters were updated in the integrated spatial model of the pipeline network and terrain to generate the modified pipeline network model. The hydraulic-hydrological coupling calculation in step 4 was then re-executed. Post-modification simulations showed that the maximum water level at well J11 dropped to 18.96m (below ground elevation of 19.23m), the maximum water level at well J17 dropped to 18.51m (below ground elevation of 18.87m), and the maximum water depth in the flood-prone area EZ-01 dropped to 0.09m, below the vehicle traffic impact threshold of 0.30m. The modification effect simulation met the requirements, and the closed-loop processing flow was terminated.

[0087] Triangular facet simplification was performed on the 3D models of roads A, B, and C, as well as the 3D solid model of the pipeline network. The number of triangular faces in the road model was reduced from approximately 860,000 to approximately 92,000, and the number of triangular faces in the pipeline network model was reduced from approximately 1,240,000 to approximately 137,000. The texture map resolution was downsampled from 2048×2048 to 512×512. The lightweight 3D model was registered as a layer on the urban geospatial base map (CGCS2000 coordinate system). A 120-minute water depth distribution sequence was overlaid onto the base map as a time-series layer every 60 seconds, generating multi-source data fusion display data. This supports dynamic playback of the water accumulation evolution process in the flood-prone area EZ-01 on the display terminal, and allows users to click on any pipe segment or node to query its flow rate and water level time-series attributes. Simultaneously, the pipeline network spatial topology map and attribute information are uploaded to the cloud analysis platform, and pipeline collision detection is performed (it was detected that there is one spatial intersection between pipe segment P18 and the water supply pipeline, with a net distance of 0.08m, which is lower than the standard requirement of 0.15m). The collision detection results are then sent back to the local BIM model, and the collision attributes of the corresponding pipe segment of P18 are automatically marked, completing the two-way data synchronization between the cloud and the local platform.

[0088] Throughout the implementation process, the data starts from the road BIM parameters and terrain DEM of planning area A. Step 1 unifies the coordinates and overlays the space to form an integrated spatial data base. Step 2 connects the pipeline BIM parameters and constructs a topology map on this basis. Step 3 uses the terrain and pipeline spatial information from the first two steps to complete the division of catchment areas and the calculation of the comprehensive runoff coefficient (e.g., the comprehensive runoff coefficient of zone Z3 is 0.629). Step 4 substitutes the runoff coefficient and area parameters into the flow production formula to obtain the inflow sequence of each zone. Then, the unsteady flow of the pipeline network is solved by the Saint-Venant equations, and the time series data of water level and flow rate of each node and pipe segment are output. Step 5 directly consumes these time series data to calculate the flow capacity utilization rate (e.g., the utilization rate of pipe segment P12 is 1.568) and generates a renovation plan. After the renovation, step 4 is re-executed to form a closed-loop verification. Step 6 then integrates and displays all three-dimensional models and simulation time series results in a lightweight manner, realizing a complete data link from the original engineering parameters to the final visualized renovation plan.

[0089] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A method for three-dimensional digital modeling of underground pipelines based on GIS and BIM, characterized in that, Includes the following steps: Acquire BIM parameter data and geospatial data of road engineering in the target area, unify the spatial coordinate reference of the road engineering BIM parameter data and geospatial data, and overlay and register the three-dimensional linear model of the road engineering, the three-dimensional outline model of the building and the three-dimensional terrain surface to generate an integrated spatial data base of roads, buildings and terrain. Obtain BIM parameter data of underground pipe network in the target area, map the spatial coordinates of each node and pipe segment in the pipe network BIM parameter data to a unified spatial coordinate reference, generate a pipe network spatial topology map based on the upstream and downstream connection relationship between each node, and spatially overlay the pipe network spatial topology map with the terrain surface to generate an integrated spatial model of pipe network and terrain. Based on the integrated spatial data base of roads, buildings, and terrain and the integrated spatial model of pipelines and terrain, the surface of the target area is divided into water catchment zones, the comprehensive runoff coefficient of each water catchment zone is calculated, the correspondence between each water catchment zone and the storm drain is established, and surface runoff parameter data is generated. Based on the design rainfall process data and surface runoff parameter data, the surface runoff of each catchment area is calculated at each time step. The inflow sequence of each rainwater inlet is used as the boundary condition. Based on the integrated spatial model of pipe network and topography, the hydraulic and hydrological coupling calculation is performed using the pipe network unsteady flow solution method based on the Saint-Venant equations to generate the simulation results of regional flooding. Based on the simulation results of local flooding, the flow capacity utilization rate of each pipe section is calculated, pipe sections with insufficient flow capacity and overflow nodes are marked, the cause of overflow is determined and the parameters for modification measures are generated, and the pipeline network modification plan is generated by summarizing the results.

2. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The process of unifying the spatial coordinate reference of road engineering BIM parameter data and geospatial data includes: Using the geodetic coordinate system in the geospatial data as the reference coordinate system, the local engineering coordinates of each element in the road engineering BIM parameter data are mapped to the reference coordinate system through a coordinate transformation matrix. The terrain surface is trimmed and fitted according to the three-dimensional line shape of the road centerline, and the building outline is projected onto the terrain surface to obtain its bottom elevation, thus completing the positioning of the road, building and terrain in the same coordinate space. When the vertical design parameters of the road, the building layout, or the terrain data change, the changed parameter data is obtained, and the geometric parameters and spatial topological relationships of the corresponding elements in the integrated spatial data base of the road, building, and terrain are incrementally updated.

3. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The pipeline network spatial topology map records the connection node identifiers, flow directions, and the number of incoming and outgoing pipeline segments for each pipeline segment; The flow direction is determined based on the difference in pipe bottom elevation between the start and end points of each pipe segment. The end with the higher pipe bottom elevation is the upstream node, and the end with the lower pipe bottom elevation is the downstream node. When the slope of the pipe segment is zero, the flow direction is assigned according to the design document. When generating the integrated spatial model of the pipeline network and terrain, a three-dimensional solid geometric model of each pipe segment is generated based on the pipe diameter and pipe material parameters of each pipe segment, and a three-dimensional solid geometric model of each manhole is generated based on the manhole diameter and manhole depth parameters. The three-dimensional solid geometric models of each pipe segment and the three-dimensional solid geometric models of each manhole are assembled according to the connection relationship in the pipeline network spatial topology diagram and spatially superimposed on the terrain surface.

4. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The process of dividing the catchment area is as follows: The surface water flow direction of each grid cell is calculated based on the elevation value of each grid cell in the topographic DEM data. The set of grid cells whose water flow direction converges to the same drainage outlet is defined as a catchment area, and the location of roadside ditches and drainage ditches is used as the constraint condition of the area boundary. Obtain the cross slope and longitudinal slope of each road, and correct the direction of surface water flow at each point on the road surface according to the combined direction of the cross slope and longitudinal slope, so that the direction of surface water flow in the road area is guided from the cross slope of the road to the side ditches or rainwater inlets on both sides of the road.

5. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The comprehensive runoff coefficient is calculated as follows: The ratio of the area of ​​each type of underlying surface in each catchment area to the total area of ​​that catchment area is weighted and summed with the corresponding runoff coefficient. The underlying surface types include road surfaces, building roofs, green spaces, and bare soil. The surface runoff parameter data include the area of ​​each catchment area, the comprehensive runoff coefficient, the runoff path length, the average runoff time, and the number and location of storm drains in each catchment area.

6. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The calculation of surface runoff for each catchment area at each time step includes: Rainfall intensity is uniformly converted into water volume per unit area per unit time, and the area of ​​each catchment zone is uniformly converted into square meters; the surface runoff of the catchment zone within each time step is obtained by multiplying the rainfall intensity within each time step by the area of ​​the catchment zone and the comprehensive runoff coefficient. The duration of the time step is no greater than the time interval between adjacent data points on the rainfall intensity variation curve; the time delay of the surface runoff reaching the corresponding storm inlet is calculated based on the runoff path length and average runoff time of each runoff zone, and the inflow sequence of each storm inlet within each time step is generated.

7. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The hydraulic-hydrological coupling calculation includes: When the calculated water level of a node exceeds the ground elevation corresponding to the node within a certain time step, it is determined that the node has overflowed. The overflow amount of the node is the positive part of the difference between the total flow into the node within the time step and the sum of the full flow capacity of each downstream pipe section connected to the node under the current water level conditions. When the difference is negative or zero, the overflow amount is zero. The overflow is distributed to the surface at the location of the node, and the diffusion process of the surface water flow is solved using a two-dimensional shallow water equation to obtain the distribution range of the overflow water on the surface and the water depth at each location. The simulation results of the waterlogging in the area include the distribution of surface water depth, waterlogging range, flow rate of each pipe section, water level of each node, and the evolution sequence of water depth and waterlogging range over time at each time step.

8. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, The flow capacity utilization rate is the ratio of the maximum flow rate of the pipe section over all time steps during the simulation to the theoretical flow capacity of the pipe section under full flow conditions. The theoretical flow capacity is calculated using the Manning formula based on pipe diameter, pipe slope, and pipe roughness coefficient; pipe sections with flow capacity utilization exceeding a preset utilization threshold are marked as pipe sections with insufficient flow capacity. Based on the pipe slope and pipe roughness coefficient of the pipe section with insufficient flow capacity, under the condition that the pipe slope and pipe material remain unchanged, the Manning formula is used to back-calculate the minimum pipe diameter value corresponding to the full flow capacity when it is not lower than the design drainage flow rate, and the pipe diameter upgrade parameters of the pipe section are generated.

9. The method for three-dimensional digital modeling of underground pipelines based on GIS and BIM according to claim 1, characterized in that, After generating the pipeline renovation plan, the process further includes: updating the pipe diameter upgrade parameters of each pipe segment and the renovation measure parameters of each node in the pipeline renovation plan to the integrated spatial model of pipeline network and terrain, generating the integrated spatial model of pipeline network and terrain after renovation, re-performing the hydraulic and hydrological coupling calculation based on the integrated spatial model of pipeline network and terrain after renovation and the same design rainfall process data, generating the simulation results of waterlogging in the area after renovation, comparing the simulation results of waterlogging in the area after renovation with the simulation results of waterlogging in the area before renovation, extracting the changes in water depth, water area and water duration in each area after renovation, and generating the renovation effect simulation data. If there are still areas in the pre-simulation data of the renovation effect that have water depth exceeding the preset water depth threshold, the renovation measures parameters of the corresponding areas in the pipeline renovation plan will be adjusted and the effect simulation process will be performed again until the water depth of all areas does not exceed the preset water depth threshold or the preset iteration number limit is reached.

10. A 3D digital modeling system for underground pipelines based on GIS and BIM, used to execute the 3D digital modeling method for underground pipelines based on GIS and BIM as described in any one of claims 1 to 9, characterized in that, include: The spatial data base construction module is used to acquire BIM parameter data and geospatial data of road projects in the target area, and to perform unified processing and overlay registration of the BIM parameter data of road projects and geospatial data to generate an integrated spatial data base of roads, buildings and terrain. The pipeline spatial model construction module is used to acquire BIM parameter data of underground pipelines in the target area, map the pipeline BIM parameter data to a unified spatial coordinate reference, generate a pipeline spatial topology map, and spatially overlay the pipeline spatial topology map with the terrain surface to generate an integrated spatial model of pipeline and terrain. The surface runoff parameter generation module is used to divide the surface of the target area into runoff zones based on the integrated spatial data base of roads, buildings and terrain and the integrated spatial model of pipeline network and terrain, calculate the comprehensive runoff coefficient of each runoff zone, establish the correspondence between each runoff zone and rainwater inlet, and generate surface runoff parameter data. The hydraulic-hydrological coupling calculation module is used to calculate the surface runoff of each catchment area at each time step based on the design rainfall process data and the surface runoff parameter data. The inflow sequence of each rainwater inlet is used as the boundary condition. Based on the integrated spatial model of pipe network and topography, the hydraulic-hydrological coupling calculation is performed using the pipe network unsteady flow solution method based on the Saint-Venant equations to generate the simulation results of regional waterlogging. The pipeline renovation scheme generation module is used to calculate the flow capacity utilization rate of each pipe section based on the flood simulation results of the area, mark the pipe sections with insufficient flow capacity and overflow nodes, determine the cause of overflow and generate renovation measures parameters, and summarize and generate a pipeline renovation scheme.

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