A method and system for urban road pipeline relocation rehearsal

Abstract

The present application relates to the technical field of computer-aided design, in particular to a kind of urban road pipeline relocation pre-play method and system.The present application first in three-dimensional pre-play model, the entity of pre-excavation is discretized, further in combination with the bonding strength parameter of contact surface between adjacent grid earthwork determines the topological network of soil;Residual support parameters and all support weak grid earthwork of each construction day are solved based on the maximum flow minimum cut algorithm by generating pre-excavation trench entity day by day and updating topological network of soil, further obtain the support flow loss index of each construction day, and judge whether there is relocation risk in critical early warning construction day.The present application maps soil mechanics into dynamic topological network of soil, and uses the maximum flow minimum cut algorithm to quantitatively pre-play support flow loss in each stage of construction, solves the problem that traditional collision detection cannot pre-warn non-contact sliding risk, and combines safety red line to evaluate relocation risk, improves the physical reliability of pipeline relocation pre-play in complex environment.

Description

Technical Field

[0001] This invention relates to the field of computer-aided design technology, specifically to a method and system for pre-simulating the relocation of urban road pipelines. Background Technology

[0002] In urban road reconstruction and expansion projects or pipeline relocation projects, the excavation of new deep foundation pits and trenches often encroaches on complex underground confined spaces. To ensure construction safety and minimize the impact on existing facilities, three-dimensional pre-simulation of pipeline relocation is crucial. Existing computer-aided design systems typically use geometric bounding box algorithms to simplify underground pipelines into standard cylinders with absolute coordinates. By statically detecting whether there is spatial collision between the new pipeline and existing pipelines, the geometric feasibility of the relocation plan can be determined.

[0003] However, pipeline safety is highly dependent on the physical support of the underlying soil. Traditional collision detection cannot identify the loss of supporting media caused by the erosion of the adjacent soil, making it difficult to predict non-contact pipeline slippage risks. Secondly, existing models are mostly static comparisons and fail to establish a dynamic relationship with the construction progress axis. They cannot quantify the cumulative attenuation of supporting media as the process progresses, nor do they take into account the pressurized decommissioning nodes of old pipelines. This makes it difficult to dynamically quantify risks as construction progresses, resulting in low efficiency and safety of urban road pipeline relocation simulations. Summary of the Invention

[0004] To address the technical problem of poor simulation results for urban road pipeline relocation in existing technologies, the present invention aims to provide a method and system for urban road pipeline relocation simulation, the specific technical solution of which is as follows: A method for rehearsing urban road pipeline relocation, the method comprising: Obtain the avoidance envelope entity of existing pipelines in the 3D pre-study model; discretize the pre-excavated entity into a grid earthwork matrix, obtain the bonding strength parameters of the contact surface between adjacent grid earthworks, and map the grid earthwork matrix into a soil topology network; According to the construction plan, pre-excavated trench entities are generated daily in the pre-excavated entities. The soil topology network is updated daily by combining all grid earthwork within the pre-excavated trench entities. The residual support parameters and all weak support grid earthwork of the updated soil topology network are solved based on the maximum flow minimum cut algorithm for the corresponding construction day. Based on the decay characteristics of the residual support parameters of the soil topology network up to the planned shutdown period of existing pipelines, the support loss index for each construction day is obtained, and the critical warning construction day is determined. On the critical early warning construction day, based on the deviation of the support loss index from the preset safe loss parameter, it is determined whether there is a relocation risk. If there is a risk, the risk entity is located based on the distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the weak support grid soil. After performing collision interference detection with the avoidance envelope entity in the three-dimensional pre-simulation model, a support model is generated.

[0005] Furthermore, the method for obtaining the avoidance envelope entity of the existing pipeline includes: The detection error is determined based on the detection source of the existing pipeline, and the avoidance envelope entity of the existing pipeline is obtained by expanding outward.

[0006] Furthermore, methods for mapping the grid earthwork matrix to a soil topology network include: Each grid earthwork is treated as a node, the contact surface between adjacent grid earthworks is treated as a bidirectional directed edge, and the edge capacity of the corresponding bidirectional directed edge is determined based on the bonding strength parameter of the contact surface between adjacent grid earthworks. The outermost grid earthwork nodes of the aforementioned grid earthwork matrix are taken as boundary nodes; unidirectional edges are established from the preset virtual starting node to each of the boundary nodes, and the edge capacity is set to positive infinity. The outermost mesh earthwork node of the existing pipeline's avoidance envelope entity is used as the pipeline support node; a unidirectional edge is established from each pipeline support node to the preset virtual termination node, and the edge capacity is set to positive infinity. Construct a soil topology network by combining all edges and all nodes.

[0007] Furthermore, methods for updating the soil topology network daily include: On each construction day, all grid earthwork nodes within the pre-excavated trench entity are taken as hollowing nodes, and the edge capacity of each hollowing node in the soil topology network is set to 0 to obtain the updated soil topology network.

[0008] Furthermore, the method for obtaining the residual support parameters and the earthwork of the weak support grid includes: On each construction day, the sum of the edge capacities of the minimum cut set is used as the residual support parameter; The nodes connected at both ends of the directed edge in the minimum cut set correspond to the earthwork of the grid, which is used as the earthwork to support the weak grid.

[0009] Furthermore, the method for obtaining the support churn index includes: The sum of the edge capacities of the minimum cut sets of the soil topology network before construction is used as the initial support parameter; on each construction day, the support loss index is calculated based on the deviation of the residual support parameter from the initial support parameter.

[0010] Furthermore, the method for obtaining the critical early warning construction day includes: Based on the changing characteristics of the support loss index during the planned shutdown period, the critical early warning construction day is determined.

[0011] Furthermore, the method for obtaining the risk entity includes: On the critical early warning construction day, calculate the minimum Euclidean distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the center of the earthwork of each weak support grid, and take the minimum value of the minimum Euclidean distance as the support risk distance; determine the risk entity in the pre-excavated trench entity based on the support risk distance.

[0012] Furthermore, the method for obtaining the support model after performing collision interference detection in the three-dimensional pre-simulation model includes: Determine the vertical construction clearance envelope of the risk entity in the 3D pre-simulation model; if there is spatial interference between the vertical construction clearance envelope and the avoidance envelope entity of the existing pipeline, it is determined that support cannot be generated; when there is no spatial interference, the design slope parameter of the pre-excavated trench entity corresponding to the risk entity is forcibly modified to 0 to generate vertical support.

[0013] A pre-relocation simulation system for urban road pipelines includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the pre-relocation simulation method for urban road pipelines.

[0014] The present invention has the following beneficial effects: This invention obtains the avoidance envelope entity of existing pipelines in a 3D pre-simulation model, providing avoidance space for subsequent collision interference. Then, the pre-excavated entity is discretized into a grid earthwork matrix for infinitesimal analysis. Combined with the bonding strength parameters of the contact surfaces between adjacent grid earthworks, the abstract continuum support problem in geotechnical mechanics is transformed into a network flow conduction model in computer graph theory that can be precisely quantified and solved, thereby obtaining the soil topology network and providing a foundation for accurate identification of indirect support loss. Then, according to the construction plan, pre-excavated trench entities are generated daily in the pre-excavated entity. Combined with all grid earthworks within the pre-excavated trench entities, the soil topology network is updated daily to simulate real soil flow. This invention maps soil mechanics to a dynamic soil topology network, uses the maximum flow minimum cut algorithm to quantitatively predict support loss at each stage of construction, solves the problem that traditional collision detection cannot predict non-contact slip risks, and combines safety red lines to assess relocation risks, thus improving the physical reliability of pipeline relocation prediction in complex environments. It also maps soil mechanics to a dynamic soil topology network, uses the maximum flow minimum cut algorithm to quantitatively predict support loss at each stage of construction, solves the problem that traditional collision detection cannot predict non-contact slip risks, and combines it with safety red lines to assess relocation risks, improving the physical reliability of pipeline relocation prediction in complex environments. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of a pre-relocation simulation method for urban road pipelines provided in one embodiment of the present invention. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method and system for relocating urban road pipelines according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] The following description, in conjunction with the accompanying drawings, details the specific scheme of the urban road pipeline relocation simulation method and system provided by the present invention.

[0020] Please see Figure 1 The diagram illustrates a flowchart of a pre-relocation simulation method for urban road pipelines according to an embodiment of the present invention, specifically including: Step S1: Obtain the avoidance envelope entity of existing pipelines in the 3D pre-study model; discretize the pre-excavation entity into a grid earthwork matrix, obtain the bonding strength parameters of the contact surface between adjacent grid earthworks, and map the grid earthwork matrix into a soil topology network.

[0021] In actual municipal engineering projects, the true location of existing pipelines (especially old underground pipelines) is often difficult to determine accurately, and usually relies on surveying methods such as geophysical radar to determine it. However, surveying has inherent mapping bias. If the computer relocation simulation model only relies on the detected pipeline area for collision calculation or delineation of avoidance range, it is very likely that the existing pipeline will be cut off during actual construction due to mapping bias. Based on this, the embodiments of the present invention obtain the avoidance envelope entity of existing pipelines in the three-dimensional pre-simulation model; the avoidance envelope entity is an extreme protection entity that includes the actual pipe diameter and the maximum possible mapping deviation, and its envelope boundary defines an absolute isolation zone that strictly prohibits any new pipeline trench from cutting in, providing a certain avoidance reference.

[0022] Specifically, the application programming interface (API) of the computer-aided design platform (such as AutoCAD, Civil 3D, etc.) is first called to read the platform's native World Coordinate System (WCS) as the absolute three-dimensional coordinate system of the three-dimensional pre-model; the absolute three-dimensional coordinate system provides a unified X (east-west), Y (north-south), and Z (absolute elevation) coordinate axis; Import geophysical survey drawings (or geological survey data files) into the computer-aided design platform via the data interface, then read the set of three-dimensional centerline coordinate points for each existing pipeline, connect them sequentially according to the survey direction, and fit to generate a three-dimensional centerline spatial coordinate sequence representing the physical direction of the existing pipeline; import the construction design drawings for new pipelines into the computer-aided design platform, and extract the set of three-dimensional centerline coordinate points for each new pipeline. For each (existing or newly built) pipeline, based on the structural nodes in the drawings (e.g., manhole center point, pipeline routing inflection point, or pipe diameter transition point), the originally continuous three-dimensional centerline of the pipeline is broken into multiple independent three-dimensional straight segments connected end to end; each three-dimensional straight segment corresponds to a pipeline segment as a separate pipeline entity for subsequent analysis.

[0023] Since geophysical survey drawings and new pipeline construction design drawings may come from different design units and have inconsistent coordinate systems, it is necessary to extract at least two common reference control points (such as leveling points or coordinate traverse points with known elevations at road intersections) from both the geophysical survey drawings and the new pipeline construction design drawings, and calculate the affine transformation matrix (including translation vector, rotation matrix, and scaling factor) between the common reference control points in different drawing coordinate systems and the absolute three-dimensional coordinate system. The affine transformation matrix is ​​further applied to perform coordinate coefficient mathematical transformation on the three-dimensional centerline coordinate points of the existing pipeline and the three-dimensional centerline coordinate points of the newly built pipeline, respectively, so that the coordinate values ​​are uniformly transformed and placed in the absolute three-dimensional coordinate system, thus completing the alignment of spatial data. Subsequent analysis is carried out in the absolute three-dimensional coordinate system.

[0024] It should be noted that the above-mentioned methods of importing and reading drawings and the application of affine transformations are well-known technical means and will not be elaborated further.

[0025] After constructing an absolute three-dimensional coordinate system, the avoidance envelope entity of each existing pipeline in the three-dimensional pre-simulation model can be obtained.

[0026] Preferably, in one embodiment of the present invention, since the spatial location data of existing underground pipelines usually comes from different surveying methods, the reliability of the coordinates varies significantly; and establishing a dynamic fault-tolerant expansion mechanism based on the detection source can help determine the avoidance envelope entity of the existing pipeline; therefore, the method for obtaining the avoidance envelope entity of the existing pipeline includes: The detection error is determined based on the detection source of the existing pipeline, and the avoidance envelope entity of the existing pipeline is obtained by expanding outward.

[0027] Specifically, taking any existing pipeline entity as an example, first extract the centerline of the existing pipeline entity, and at the same time read the data attribute labels of the existing pipeline entity in the geophysical exploration drawing paper (or geological exploration data file) to extract the detection source level; The system reads a preset detection accuracy mapping table, which defines the correspondence between different detection source levels and the maximum allowable error range. For example, the detection source levels include: Level A (actual measurement during trench excavation, small error, preset detection error of 0.1 meters), Level B (grounding radar detection, subject to media interference, preset detection error of 0.5 meters), and Level C (as-built drawing simulation, large uncertainty, preset detection error of 1.0 meter). The extracted detection source level is compared with the mapping table to output the detection error of the existing pipeline entity; the pipe diameter data (such as the pipeline geometric radius) of the existing pipeline entity is further read, and the pipeline geometric radius is added to the detection error obtained from the table to obtain the total radius of cross-sectional expansion. In the absolute three-dimensional coordinate system, the centerline of the extracted existing pipeline entity is used as the central axis, and the calculated total radius of cross-sectional expansion is used as the radius. A closed three-dimensional cylindrical shell entity is generated by stretching outward, which is the avoidance envelope entity. For pipe corner joints or diameter change areas, the spherical Boolean union algorithm is used to geometrically smooth the gaps at the stretching turning point (a well-known technical means, which will not be described in detail) to ensure that the generated avoidance envelope entity is a completely closed and continuous spatial body.

[0028] The safety of existing pipelines depends on the physical support of the soil directly below and diagonally below them. Soil is a continuous medium, consisting of a physical relationship of interlocking support between a quantitative amount of soil blocks. To analyze the loss of soil support, this embodiment of the invention first discretizes the pre-excavated entity into a grid earthwork matrix, so that the pre-excavated entity is cut into countless tiny grid earthworks, each grid earthwork representing a stress micro-element.

[0029] Specifically, the pre-excavated entity is the underground construction space of the urban road. The underground construction space is divided into three dimensions according to a preset fixed side length, resulting in several cubic grid soil bodies. The preset fixed side length ranges from 0.1 to 0.5m, and is 0.2m in this example. The preset fixed side length must be less than or equal to 1 / 2 of the minimum diameter of the existing pipeline avoidance envelope entity section to prevent small-diameter pipelines from disappearing in the grid.

[0030] It should be noted that, due to the design slope of the newly constructed pipeline trench, the cross-section of the pre-excavated entity is usually trapezoidal or other irregular polygons. Using a standard cube for spatial division will inevitably generate incomplete grid earthwork at the slope boundary. Therefore, it is necessary to supplement the rules for the selection and conversion of incomplete grid earthwork: the three-dimensional division is divided from the centerline of the pre-excavated entity from the inside to the outside. For incomplete grid earthwork, the volume of incomplete grid earthwork is calculated. If the volume is greater than 50% of the volume of complete grid earthwork, it is approximated as a complete cube grid earthwork and retained; otherwise, it is discarded.

[0031] The bonding strength of the contact surface between adjacent grid soil blocks represents the shear resistance and slip resistance of the soil blocks. Therefore, it is also necessary to obtain the bonding strength parameters of the contact surface between adjacent grid soil blocks, and then map the grid soil block matrix into a soil topology network. This will transform the abstract continuum support problem in geotechnical mechanics into a network flow conduction model (i.e., soil topology network) that can be accurately quantified and solved in computer graph theory, providing a basis for subsequent accurate identification of indirect support loss.

[0032] Considering the bidirectional interaction characteristic of force transmission within the soil, the contact surfaces between meshed soil blocks can be mapped as bidirectional directed edges characterizing the bonding strength of the soil blocks, in order to simulate the shear failure force required to cut off adjacent soil blocks; furthermore, considering that a regular mesh graph is a divergent network in graph theory, lacking a "single source" and "single convergence point" for overall global calculation, additional virtual start nodes and end nodes need to be preset in order to construct a standard directed graph (ST network); In this process, since the deep foundation of the pre-excavated entity can be regarded as an absolutely stable support source, and the soil close to the pipeline can be regarded as the connecting support boundary of the pipeline, the preset virtual nodes are connected to the boundary nodes to construct unidirectional edges, and the edge capacity is forcibly set to positive infinity to forcibly lock the boundary optimization range of the subsequent graph cut algorithm, ensuring that the physical rupture surface most prone to collapse absolutely and only occurs on the corresponding directional edge of the contact surface between the internal grid soil representing the actual excavated soil. Based on this, in a preferred embodiment of the present invention, the method for mapping a grid earthwork matrix to a soil topology network includes: Each grid earthwork is treated as a node, the contact surface between adjacent grid earthworks is treated as a bidirectional directed edge, and the edge capacity of the corresponding bidirectional directed edge is determined based on the bonding strength parameter of the contact surface between adjacent grid earthworks. The outermost grid earthwork nodes of the grid earthwork matrix are used as boundary nodes; unidirectional edges are established from the preset virtual starting node to each boundary node, and the edge capacity is set to positive infinity. The outermost mesh earthwork node of the existing pipeline avoidance envelope entity is used as the pipeline support node; a unidirectional edge is established from each pipeline support node to the preset virtual termination node, and the edge capacity is set to positive infinity. Construct a soil topology network by combining all edges and all nodes.

[0033] Specifically, each grid earthwork in the grid earthwork matrix is ​​first treated as a node, the contact surface between adjacent grid earthworks is treated as a bidirectional directed edge, and the bonding strength parameter of the contact surface between adjacent grid earthworks is used as the edge capacity of the corresponding bidirectional directed edge; the edge capacity quantifies the shear failure force required to cut off adjacent earthworks. Taking the contact surface between any two adjacent grid soil sections as an example, the method for obtaining the bonding strength parameters of the contact surface between two adjacent grid soil sections includes: Import and store the unit weight (weight of soil per unit volume, in kN / m³) of soil layers at different elevations. 3 ), cohesion (unit: kPa or kN / m) 2 The report includes the engineering geological survey data on the internal friction angle; the thickness and corresponding unit weight of the overburden layer on the contact surface are used to perform layered weighted summation to obtain the self-weight pressure of the overburden layer on the contact surface (unit area) (in kN / m²).2 ); Using the Coulomb shear strength formula, multiply the self-weight pressure of the overlying soil layer (per unit area) by the tangent of the internal friction angle, add the soil cohesion, and multiply the sum by the area of ​​the contact surface (unit: m²). 2 ), to obtain the basic bonding strength parameters of the contact surface; It should be noted that when the contact surface spans two different soil layers, the cohesion and internal friction angle are taken as the minimum values ​​of the two soil layers to follow the principle of engineering safety and conservatism. If the foundation bond strength parameter is less than or equal to 0, it is forcibly modified to a preset minimum positive number such as 0.01 to prevent division overflow or deadlock caused by the blocking capacity being zero in subsequent calculations. In this study, due to the physical bonding force between the grid soil masses in the underground space, and the significant difference between the downward support force and the horizontal frictional force of the soil under gravity, a spatial normal vector of the contact surface between adjacent grid soil masses is extracted to accurately reflect the physical difference between the vertical support force and the horizontal lateral pressure of the soil in the grid soil matrix. The angle between the spatial normal vector and the Z-axis (vertical direction) in the absolute three-dimensional coordinate system is calculated, and a differentiation directional coefficient is assigned. When the included angle is less than 45 degrees, it is determined that the contact surface mainly bears the vertical gravity support, and a first directional coefficient is assigned (e.g., 1.0, which is used to characterize the high cost required to block the connection between the upper and lower grids). The basic bonding strength parameter is then multiplied by the first directional coefficient to obtain the bonding strength parameter of the contact surface. When the included angle is ≥45 degrees, it is determined that the contact surface mainly bears the horizontal lateral earth pressure. A small second directional coefficient is assigned (e.g., 0.5, which is smaller than the first directional coefficient, to characterize that the lateral connection is more easily cut off). The foundation bond strength parameter is then multiplied by the second directional coefficient to obtain the bond strength parameter of the contact surface.

[0034] As another example, the lateral shear strength and vertical bearing capacity of the soil can also be assessed based on the spatial orientation of the contact surface, thereby determining the bond strength parameters; specifically: When the included angle is less than 45 degrees, it is determined that the contact surface mainly bears the vertical gravity support. The characteristic value of the foundation bearing capacity fak (unit kPa) of the corresponding soil layer in the geological survey report is directly read, and it is multiplied by the area of ​​the contact surface to obtain the bonding strength parameter of the contact surface. When the included angle is ≥45 degrees, it is determined that the contact surface mainly bears the horizontal lateral earth pressure. First, the self-weight pressure of the overlying soil layer is multiplied by the preset static earth pressure coefficient K0 (the value is provided by the geological survey report, usually 0.5-0.7) to obtain the lateral normal stress. Substitute the lateral normal stress into the Coulomb shear strength formula, and then multiply it by the area of ​​the contact surface to obtain the bonding strength parameter of the contact surface. Further filter the outermost grid earthwork in the grid earthwork matrix: if a certain grid earthwork has fewer than 6 adjacent grid earthworks in 3D space (i.e. exposed on the outer boundary of the grid earthwork matrix, excluding the top surface), then mark its corresponding node as a boundary node; initialize a preset virtual starting node S (representing the deep, absolutely stable native earth) without any 3D spatial coordinate attributes; establish unidirectional (directed) edges starting from the preset virtual starting node and pointing to each boundary node, and call the maximum floating-point value supported by the computer program to set the edge capacity of these unidirectional edges to positive infinity; Read the pre-generated avoidance envelope entity of the existing pipeline in the absolute three-dimensional coordinate system, use the three-dimensional geometric collision algorithm to detect the grid earthwork that geometrically intersects and overlaps with the outer surface of the avoidance envelope entity or is completely located within its inner boundary, extract and mark it as pipeline support node; initialize a preset virtual termination node T without spatial coordinate attributes (representing the existing pipeline as the overall force target); establish unidirectional (directed) edges starting from each pipeline support node and uniformly pointing to the preset virtual termination node, and also set the edge capacity of these unidirectional directed edges to positive infinity; Finally, all generated nodes (including the nodes corresponding to the grid earthwork and two preset virtual nodes), as well as all generated directed edges (including bidirectional directed edges carrying physical capacity and unidirectional edges carrying positive infinite capacity), are integrated and encapsulated into a standard and complete directed graph data structure, namely the soil topology network, which provides the foundation for the subsequent execution of the maximum flow minimum cut algorithm.

[0035] Step S2: Generate pre-excavated trench entities in the pre-excavated entities daily according to the construction plan. Combine all the grid earthwork within the pre-excavated trench entities and update the soil topology network daily. Solve the residual support parameters and all weak support grid earthwork of the updated soil topology network on the corresponding construction day based on the maximum flow minimum cut algorithm.

[0036] Because the trenches for pipeline relocation in urban roads are excavated in sections on a daily basis, the loss of support caused by earthwork hollowing is a dynamic process that accumulates with the excavation. A one-time static comparison of the entire newly built trench not only deviates from the actual process, but also obscures the critical point of nonlinear collapse of the support force. Based on this, the embodiment of the present invention first generates a pre-excavated trench entity in the pre-excavated entity on a daily basis according to the construction plan. The pre-excavated trench entity is the (cumulative) excavated part in the underground construction space of the urban road.

[0037] Specifically, the total number of construction days and daily excavation advance length are obtained through the construction schedule of urban road pipeline relocation; on each construction day, the cumulative excavation advance length L is determined, and then the corresponding length of pre-excavated trench entity is generated. Known technical methods are briefly described here: For example, on the nth construction day, the central axis of the underground construction space of the urban road is read, and the excavation advance length Ln is extended along the axis in the absolute three-dimensional coordinate system. The design bottom surface range of the trench corresponding to this length is intercepted. Then, combined with the read cross-sectional design slope parameters, the trench bottom surface is stretched upward to generate an inverted trapezoidal three-dimensional slope profile. The inverted trapezoidal three-dimensional slope profile is instantiated as a solid model and defined as the pre-excavated trench entity on the nth construction day.

[0038] If the excavated soil (the pre-excavated trench entity) can no longer provide connection and support for existing pipelines, the soil topology network is updated daily by combining all the grid soil within the pre-excavated trench entity to simulate the real soil loss environment, quantify the dynamic changes in support force over time, and prepare for the subsequent dynamic capture of critical early warning construction days when support loss exceeds the standard.

[0039] Preferably, in one embodiment of the present invention, considering that the excavated grid soil within the trench no longer provides any support or lateral constraint for the existing pipeline, its corresponding nodes are set as hollow nodes; furthermore, the edge capacity of the corresponding edges of the hollow nodes in the soil topology network is forcibly reduced to zero to characterize the disappearance of the physical bonding force between the grids, thereby helping to quantify the mechanical instability caused by the "void" at the bottom of the pipeline support; then the method for updating the soil topology network daily includes: On each construction day, all grid earthwork nodes within the pre-excavated trench entity are taken as hollowing nodes, and the edge capacity of each hollowing node in the soil topology network is set to 0 to obtain the updated soil topology network.

[0040] It should be noted that when updating the soil topology network, only the edge capacity of the edges connected to the hollowed-out nodes is modified, and the capacity status of the other edges is not modified.

[0041] The collapse of the soil under the pipeline occurs on the sliding surface with the least shear resistance. The maximum flow minimum cut algorithm can help find the minimum cost section that blocks the connectivity of the updated soil topology network. This section is physically equivalent to the slip surface of the soil that is most prone to fracture. This can help analyze the residual support of the slip surface and the corresponding weak support grid soil. Based on this, the embodiments of the present invention use the maximum flow minimum cut algorithm to solve for the residual support parameters and all weak support grid earthwork of the updated soil topology network on the corresponding construction day; the residual support parameters represent the minimum shear strength of the slip surfaces in the remaining construction space soil (updated soil topology network) on the corresponding construction day, that is, the minimum bottom support capacity to keep the pipeline from falling or settling; the weak support grid earthwork represents the grid earthwork corresponding to the slip surfaces in the remaining construction space soil (updated soil topology network) on the corresponding construction day.

[0042] It should be noted that the application of the maximum flow minimum cut algorithm is a well-known technical means and will not be described in detail here; in one embodiment of the present invention, the maximum flow minimum cut algorithm is used to obtain the minimum cut set in the soil topology network.

[0043] Preferably, in one embodiment of the present invention, considering that the edge capacity corresponds to the bonding strength of the grid soil, the minimum cut set contains the weakest and most easily broken edge in the soil topology network under the current construction state, which corresponds to the soil slip surface. Therefore, the sum of the edge capacities within the minimum cut set can characterize the minimum shear strength of the slip surface, thereby determining the residual support parameters and the corresponding grid soil volume. The method for obtaining the residual support parameters and the soil volume of the weakly supported grid includes: On each construction day, the sum of the edge capacities of the minimum cut set is used as the residual support parameter; the earthwork corresponding to the nodes connected at both ends of the directed edges in the minimum cut set is used as the earthwork for supporting the weak grid.

[0044] It should be noted that in actual construction projects, many shallow excavations will not touch deeply buried existing pipelines, i.e., there is no threat of support loss. For such cases, the embodiments of the present invention can also add an elevation filtering precondition: the soil topology network is updated only when the lowest elevation of the pre-excavated trench entity is lower than the highest elevation of the avoidance envelope entity of any existing pipeline. This precondition can improve the calculation response speed and engineering practicality of the simulation system.

[0045] Step S3: Based on the attenuation characteristics of the residual support parameters of the soil topology network up to the planned shutdown period of the existing pipeline, obtain the support loss index for each construction day and determine the critical warning construction day.

[0046] Considering that any settlement caused by the loss of support before the existing pipeline is shut down could lead to serious accidents, the support loss index is obtained by analyzing the nonlinear decay characteristics of the residual support parameters with the depth and breadth of excavation during the planned shutdown period. By establishing a mapping relationship between the construction calendar and the evolution of physical support, this can help quantify the dynamic changes in risks during the maintenance period of the existing pipeline, so as to predict the settlement risks during the construction process and determine the critical warning construction day.

[0047] Preferably, in one embodiment of the present invention, since the soil support state before construction (initial support parameters) represents the complete bearing capacity of the original underground geological strata, it can be used as an initial benchmark; by analyzing the deviation of the residual support parameters relative to the initial support parameters, the degree of support weakening can be intuitively quantified, thereby measuring the support loss index, which reflects the depth of damage to the bottom of the existing pipeline caused by construction activities; the method for obtaining the support loss index includes: The sum of the edge capacities of the minimum cut sets of the soil topology network before construction is used as the initial support parameter; on each construction day, the support loss index is calculated based on the deviation of the residual support parameter from the initial support parameter.

[0048] Specifically, the calculation of the initial support parameters is the same as the calculation of the residual support parameters for each construction day in step S2, and will not be repeated here. Taking any existing pipeline as an example, on each construction day up to its planned shutdown period, the initial support parameters are subtracted from the residual support parameters of the soil topology network, the difference is divided by the initial support parameters to eliminate the dimension, and the quotient is truncated to a negative value to obtain the support loss index for the construction day. According to the principle of network flow, since the construction excavation only sets the capacity of some edges in the soil topology network to 0 and does not add any support, the initial support parameter is always greater than or equal to the residual support parameter of each construction day. By subtracting the residual support parameter of the soil topology network from the initial support parameter, a non-negative loss difference is ensured.

[0049] It should be noted that the initial support parameter represents the complete support benchmark provided by the original underground geological strata for the pipeline. When the initial support parameter is close to 0, it indicates that there is a numerical error or that the existing pipeline may have been completely exposed to the air. Under this condition, the calculated support loss index has no mechanical basis. In order to avoid the collapse due to the "division by zero error", it is necessary to perform overflow prevention and initial condition identification based on the program: if the initial support parameter is less than a preset small positive number such as 0.01, a high risk warning of suspension will be directly output and the simulation will be terminated.

[0050] After obtaining the support loss index, the critical warning construction day is further determined.

[0051] Preferably, in one embodiment of the present invention, considering that the peak of support loss during the existing pipeline's maintenance period is the highest point at which a settlement accident occurs, and that the first maximum value point represents the moment when the connectivity of the underground soil is most severely damaged, using this as the critical early warning construction day can quickly pinpoint the date of risk occurrence; therefore, the method for obtaining the critical early warning construction day includes: Based on the changing characteristics of the support loss index during the planned shutdown period, the critical early warning construction day is determined.

[0052] Specifically, the construction day corresponding to the maximum support loss index during the planned shutdown period will be designated as the critical warning construction day; where the support loss index is at its maximum value for consecutive construction days, the construction day corresponding to the first maximum value will be designated as the critical warning construction day.

[0053] In other examples, implementers may also use the construction day on which the support loss index first exceeds the preset safe loss parameter (obtained in step S4) during the planned downtime as the critical warning construction day.

[0054] Step S4: On the critical early warning construction day, based on the deviation of the support loss index from the preset safe loss parameter, determine whether there is a relocation risk; if there is a risk, locate the risk entity based on the distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the weak support grid soil, and generate a support model after performing collision interference detection with the avoidance envelope entity in the three-dimensional pre-simulation model.

[0055] It should be noted that risk warnings are issued for all construction days following the critical warning construction day. This embodiment of the invention uses the critical warning construction day as an example for analysis and description.

[0056] Considering that a safety loss threshold (preset safety loss parameter) is preset, if the support loss index exceeds the safety loss threshold on the critical warning construction day, it indicates that there may be a risk of soil slippage, and thus a risk of pipeline relocation. Based on this, this embodiment of the invention will determine whether there is a relocation risk based on the deviation of the support loss index from the preset safety loss parameter on the critical warning construction day.

[0057] In one embodiment of the present invention, preset safety loss parameters are first calibrated based on a historical accident model; Specifically, before the relocation rehearsal, data on completed historical projects that have experienced excessive settlement or slippage of existing pipelines under similar soil conditions are extracted from an external geological and construction accident database; the support loss index on the settlement day of each historical accident project is calculated (the method is the same as in steps S1-S3, and will not be repeated); the average support loss index of all historical accident projects on the settlement day is calculated, and this average value is set as the preset safe loss parameter.

[0058] On the critical warning construction day, if the support loss index is greater than or equal to the preset safe loss parameter, it is determined that there is a risk of relocation, and it is necessary to assess whether to establish support to avoid landslide and collapse accidents; otherwise, there is no risk of relocation, and normal relocation can be carried out.

[0059] Considering that the pre-excavated trench entity closest to the soil slip surface (supporting the weak grid soil) is the direct physical source of the erosion of the existing pipeline stratum, if there is a risk of relocation, the risk entity is located based on the distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the supporting weak grid soil, and it is determined whether support can be established during its cycle.

[0060] Preferably, in one embodiment of the present invention, the method for obtaining risk entities includes: On the critical early warning construction day, calculate the minimum Euclidean distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the center of the earthwork of each weak support grid, and take the minimum value of the minimum Euclidean distance as the support risk distance; determine the risk entities in the pre-excavated trench entity based on the support risk distance.

[0061] Specifically, for the pre-excavated trench entity, the three-dimensional excavation free interface is first extracted, namely the "pit wall" and "pit bottom" of the trench. In the three-dimensional pre-simulation model, this specifically refers to the outer surface (excluding the top surface of the ground) where the pre-excavated trench entity contacts the grid soil. The minimum Euclidean distance between the center of each weakly supporting grid soil and the center point of the three-dimensional excavation free interface is calculated, and the minimum value of the minimum Euclidean distance is taken as the support risk distance. The support risk distance helps to assess the degree of risk of the pre-excavated trench entity being weakened due to the hollowing out of the surrounding soil grid. The center point of the three-dimensional excavation free interface with the minimum support risk distance is further marked as the critical risk point. The critical risk point is orthogonally projected onto the central axis of the pre-excavated trench entity to obtain the risk axis coordinates. Along the central axis with the risk axis coordinates as the midpoint, a preset support span is extended forward and backward, and the pre-excavated trench entity section within this range is taken as the risk entity. The preset support span can be taken as the length of the standard support baffle.

[0062] After identifying the risk entities, a support model is generated by performing collision interference detection in the 3D pre-simulation model.

[0063] Preferably, in one embodiment of the present invention, the vertical construction clearance envelope of the risk entity in the three-dimensional pre-simulation model is determined; if there is spatial interference between the vertical construction clearance envelope and the avoidance envelope entity of the existing pipeline, it is determined that support cannot be generated; when there is no spatial interference, the design slope parameter of the pre-excavated trench entity corresponding to the risk entity is forcibly modified to 0 to generate vertical support.

[0064] Specifically, in the 3D pre-simulation model, the central axis of the risk entity is locked as the geometric reference axis, and a cuboid spatial outline of a preset width is constructed along the Z-axis upward to the ground surface. This cuboid spatial outline is defined as the vertical construction clearance envelope of the risk entity, which represents the minimum unobstructed space required for subsequent piling machinery or support equipment to be lowered. The preset width is a preset distance on each side of the outer radial direction of the risk entity, which is between 0.6 meters and 1.0 meters. In this example, it is 1 meter to provide construction operation space. Perform three-dimensional geometric interference collision detection on the vertical construction clearance envelope and the avoidance envelope of existing pipelines: If interference exists (such as spatial intersection or geometric penetration), it is determined that the construction conditions for implementing vertical support are not met. An explicit interference avoidance mark is generated at the collision coordinate location, and a manual intervention prompt is output for the designer to evaluate. If there is no interference, the conditions for implementing vertical support are determined. The native primitive modification API interface of the computer-aided design platform is called to forcibly modify the design slope parameter of the pre-excavated trench entity corresponding to the risk entity to 0. Parallel intersecting cuboid shell models are generated along the Z-axis at positions close to both sides of the risk entity. The Z-axis depth of the cuboid shell model is drilled from the ground surface projection plane to the bottom of the corresponding pre-excavated trench, with an additional 2-meter embedment depth. This cuboid shell model is defined as the three-dimensional model of vertical support. The above support generation must be carried out under the evaluation and confirmation of the designer.

[0065] Based on the same inventive concept, this invention also proposes an urban road pipeline relocation pre-simulation system. The system includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the computer program, it implements an urban road pipeline relocation pre-simulation method described in steps S1-S4.

[0066] In summary, this invention obtains the avoidance envelope entity of existing pipelines in the 3D pre-simulation model; discretizes the pre-excavated entity into a grid earthwork matrix, obtains the bonding strength parameters of the contact surfaces between adjacent grid earthworks, and maps the grid earthwork matrix into a soil topology network; generates pre-excavated trench entities in the pre-excavated entity daily according to the construction plan, and updates the soil topology network daily by combining all grid earthworks within the pre-excavated trench entity; solves the residual support parameters of the updated soil topology network and all weakly supported grid earthworks on the corresponding construction day based on the maximum flow minimum cut algorithm; obtains the support loss index for each construction day based on the decay characteristics of the residual support parameters of the soil topology network up to the planned shutdown period of the existing pipeline, and determines the critical warning construction day; on the critical warning construction day, judges whether there is a relocation risk based on the deviation of the support loss index from the preset safe loss parameter; if there is a risk, locates the risk entity based on the distance between the pre-excavated trench entity and the weakly supported grid earthworks, and generates a support model after performing collision interference detection in the 3D pre-simulation model. This invention maps soil mechanics into a dynamic soil topology network and uses the maximum flow minimum cut algorithm to quantitatively predict support loss at each stage of construction. This solves the problem that traditional collision detection cannot predict non-contact slip risks. Furthermore, it combines safety red lines to assess relocation risks, thereby improving the physical reliability of pipeline relocation prediction in complex environments.

[0067] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0068] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A method for rehearsing urban road pipeline relocation, characterized in that, The method includes: Obtain the avoidance envelope entity of existing pipelines in the 3D pre-study model; discretize the pre-excavated entity into a grid earthwork matrix, obtain the bonding strength parameters of the contact surface between adjacent grid earthworks, and map the grid earthwork matrix into a soil topology network; According to the construction plan, pre-excavated trench entities are generated daily in the pre-excavated entities. The soil topology network is updated daily by combining all grid earthwork within the pre-excavated trench entities. The residual support parameters and all weak support grid earthwork of the updated soil topology network are solved based on the maximum flow minimum cut algorithm for the corresponding construction day. Based on the decay characteristics of the residual support parameters of the soil topology network up to the planned shutdown period of existing pipelines, the support loss index for each construction day is obtained, and the critical warning construction day is determined. On the critical early warning construction day, based on the deviation of the support loss index from the preset safe loss parameter, it is determined whether there is a relocation risk. If there is a risk, the risk entity is located based on the distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the weak support grid soil. After performing collision interference detection with the avoidance envelope entity in the three-dimensional pre-simulation model, a support model is generated.

2. The method for relocating urban road pipelines according to claim 1, characterized in that, The method for obtaining the avoidance envelope entity of the existing pipeline includes: The detection error is determined based on the detection source of the existing pipeline, and the avoidance envelope entity of the existing pipeline is obtained by expanding outward.

3. The method for relocating urban road pipelines according to claim 1, characterized in that, Methods for mapping a grid earthwork matrix to a soil topology network include: Each grid earthwork is treated as a node, the contact surface between adjacent grid earthworks is treated as a bidirectional directed edge, and the edge capacity of the corresponding bidirectional directed edge is determined based on the bonding strength parameter of the contact surface between adjacent grid earthworks. The outermost grid earthwork nodes of the aforementioned grid earthwork matrix are taken as boundary nodes; unidirectional edges are established from the preset virtual starting node to each of the boundary nodes, and the edge capacity is set to positive infinity. The outermost mesh earthwork node of the existing pipeline's avoidance envelope entity is used as the pipeline support node; a unidirectional edge is established from each pipeline support node to the preset virtual termination node, and the edge capacity is set to positive infinity. Construct a soil topology network by combining all edges and all nodes.

4. The method for relocating urban road pipelines according to claim 3, characterized in that, Methods for updating the soil topology network daily include: On each construction day, all grid earthwork nodes within the pre-excavated trench entity are taken as hollowing nodes, and the edge capacity of each hollowing node in the soil topology network is set to 0 to obtain the updated soil topology network.

5. The method for relocating urban road pipelines according to claim 1, characterized in that, The methods for obtaining the residual support parameters and the earthwork of the weak support grid include: On each construction day, the sum of the edge capacities of the minimum cut set is used as the residual support parameter; The nodes connected at both ends of the directed edge in the minimum cut set correspond to the earthwork of the grid, which is used as the earthwork to support the weak grid.

6. The method for relocating urban road pipelines according to claim 1, characterized in that, The method for obtaining the support churn index includes: The sum of the edge capacities of the minimum cut sets of the soil topology network before construction is used as the initial support parameter; on each construction day, the support loss index is calculated based on the deviation of the residual support parameter from the initial support parameter.

7. The method for relocating urban road pipelines according to claim 1, characterized in that, The method for obtaining the critical early warning construction day includes: Based on the changing characteristics of the support loss index during the planned shutdown period, the critical early warning construction day is determined.

8. The method for relocating urban road pipelines according to claim 1, characterized in that, The methods for obtaining the risky entities include: On the critical early warning construction day, calculate the minimum Euclidean distance between the three-dimensional excavation free interface of the pre-excavated trench entity and the center of the earthwork of each weak support grid, and take the minimum value of the minimum Euclidean distance as the support risk distance; determine the risk entity in the pre-excavated trench entity based on the support risk distance.

9. The method for relocating urban road pipelines according to claim 1, characterized in that, The method for obtaining the support model after performing collision interference detection in the three-dimensional pre-model includes: Determine the vertical construction clearance envelope of the risk entity in the 3D pre-simulation model; if there is spatial interference between the vertical construction clearance envelope and the avoidance envelope entity of the existing pipeline, it is determined that support cannot be generated; when there is no spatial interference, the design slope parameter of the pre-excavated trench entity corresponding to the risk entity is forcibly modified to 0 to generate vertical support.

10. A pre-relocation simulation system for urban road pipelines, the system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the urban road pipeline relocation simulation method as described in any one of claims 1 to 9.

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