Tunnel parameterized BIM modeling method based on multi-template library integration

Abstract

The application relates to the technical field of tunnel engineering digital modeling, in particular to a tunnel parameterized BIM modeling method based on multi-template library integration, which comprises the following steps: dividing a tunnel transition section into multiple slices according to a construction step distance, and generating a candidate thickness set of each slice according to a starting point thickness, an ending point thickness, a trolley modulus and a safe driving boundary line; determining each thickness candidate combination between adjacent slices, and determining a candidate mapping relationship set satisfying a preset connection constraint between control vertices corresponding to each thickness candidate combination; determining a target thickness sequence and a vertex mapping relationship corresponding to a target selected thickness sequence according to the candidate mapping relationship set corresponding to each thickness candidate combination and the coordinates of each control vertex; and generating a three-dimensional BIM entity of the tunnel transition section according to the target selected thickness and the corresponding vertex mapping relationship. The three-dimensional BIM entity obtained by the method can be directly used to guide construction, and the construction feasibility is improved.

Description

Technical Field

[0001] This application relates to the field of digital modeling technology for tunnel engineering, specifically to a parametric BIM modeling method for tunnels based on the integration of multiple template libraries. Background Technology

[0002] In the field of tunnel engineering construction, Building Information Modeling (BIM) technology has become a core tool supporting digital management throughout the entire lifecycle of design, construction, and operation and maintenance. Tunnel lining, as a critical structure ensuring the stability of the surrounding rock and traffic safety, requires its thickness to be adjusted according to changes in the surrounding rock grade. Especially when encountering changes in geological conditions on horizontal and vertical curve sections, the accuracy of parametric modeling of the lining transition section directly affects the reliability of subsequent construction layout, quantity calculation, and on-site formwork assembly.

[0003] Currently, when dealing with such transition sections, general Building Information Modeling (BIM) modeling software typically uses a two-dimensional cross-section to sweep along a three-dimensional centerline and performs continuous interpolation smoothing operations on the cross-sectional dimensions to generate a smooth transition surface model. On-site construction personnel then carry out construction based on this transition surface model.

[0004] However, the steel formwork trolleys used for on-site secondary lining construction can only be assembled and extended according to fixed mechanical gears, and cannot achieve arbitrary changes in continuous decimals. Faced with this disconnect, construction workers usually have to rely on experience to approximate the model by rounding or segmenting it. At the same time, they also need to manually check it to avoid encroaching on the vehicle clearance limits. This not only greatly increases the difficulty of construction and wastes materials, but also makes it difficult to guarantee the safety boundaries and quality of the lining structure. As a result, the feasibility, economy and effectiveness of the construction of the tunnel transition section are seriously affected. Summary of the Invention

[0005] To address the technical problem of the transition surface models generated in related technologies being disconnected from actual construction and thus unable to be directly implemented, this application aims to provide a parametric BIM modeling method for tunnels based on the integration of multiple template libraries. The specific technical solution adopted is as follows: This application provides a parametric BIM modeling method for tunnels based on multi-template library integration, including: obtaining the starting thickness, ending thickness, trolley module, construction step distance, and safe driving boundary line of the tunnel transition section; dividing the tunnel transition section into multiple slices according to the construction step distance, and generating a set of candidate thicknesses that meet the safe driving requirements for each slice based on the starting thickness, ending thickness, trolley module, and safe driving boundary line, wherein each candidate thickness of each slice has multiple control vertices distributed circumferentially on its cross-sectional profile; determining candidate thickness combinations between adjacent slices based on the candidate thickness sets of adjacent slices, and determining a set of candidate mapping relationships between the control vertices corresponding to each candidate thickness combination that satisfy preset connection constraints; determining a target thickness sequence and vertex mapping relationships corresponding to the target selected thickness sequence based on the set of candidate mapping relationships between the control vertices corresponding to each candidate thickness combination between adjacent slices and the coordinates of each control vertex, wherein the target thickness sequence includes the target selected thickness of each slice; and generating a 3D BIM entity of the tunnel transition section based on the target selected thickness of each slice and the vertex mapping relationships corresponding to the target selected thickness sequence.

[0006] Optionally, the above-mentioned generation of a candidate thickness set that meets the safe driving requirements for each slice based on the starting thickness, ending thickness, trolley module, and safe driving boundary line includes: determining the orientation step size based on the polarity of the difference between the ending thickness and the starting thickness and the trolley module; dividing the slice by the orientation step size with the starting thickness as the initial value and the ending thickness as the target value to obtain multiple initial candidate thicknesses between the initial value and the target value, as well as the thickness change increment of each initial candidate thickness; determining the safe clearance distance of each slice based on the safe driving boundary line; and filtering out initial candidate thicknesses whose thickness change increment is greater than the safe clearance distance of each slice from the multiple initial candidate thicknesses to obtain a candidate thickness set that meets the safe driving requirements for each slice.

[0007] Optionally, the preset connection constraint is used to limit the absolute difference between the sorted indices of matching control vertices between adjacent slices to not exceed a preset neighborhood tolerance threshold. The above-mentioned determination of each thickness candidate combination between adjacent slices based on the candidate thickness set of adjacent slices, and determination of the candidate mapping relationship set between the control vertices corresponding to each thickness candidate combination that satisfies the preset connection constraint, includes: extracting the sorted indices of control vertices on the cross-sectional contours corresponding to each thickness candidate combination between adjacent slices; for all mapping relationships between each control vertex of the preceding slice and each control vertex of the following slice corresponding to each thickness candidate combination between adjacent slices, determining the cyclic index difference of each vertex pair in each mapping relationship corresponding to each thickness candidate combination, wherein a mapping relationship includes multiple vertex pairs equal to the number of control vertices in the preceding slice; determining vertex pairs with cyclic index differences greater than the preset neighborhood tolerance threshold as abnormal vertex pairs; and filtering out mapping relationships containing abnormal vertex pairs from all mapping relationships to obtain a candidate mapping relationship set.

[0008] Optionally, the above-mentioned determination of the target thickness sequence and the vertex mapping relationship corresponding to the target selected thickness sequence based on the set of candidate mapping relationships between control vertices corresponding to each thickness candidate combination between adjacent slices and the coordinates of each control vertex includes: determining the total matching distance corresponding to each candidate mapping relationship in each candidate mapping relationship set based on the coordinates of the control vertices; determining the candidate mapping relationship with the smallest total matching distance in each candidate mapping relationship set as the best mapping relationship for the corresponding thickness candidate combination, and determining the total matching distance corresponding to the best mapping relationship as the minimum mapping distance; determining the thickness sequence with the smallest cumulative mapping distance from the first slice to the last slice based on the minimum mapping distance corresponding to each thickness candidate combination; and determining the thickness sequence with the smallest cumulative mapping distance as the target thickness sequence when there is only one thickness sequence with the smallest cumulative mapping distance, and determining the best mapping relationship between adjacent slices in the target thickness sequence as the vertex mapping relationship corresponding to the target selected thickness sequence.

[0009] Optionally, determining the thickness sequence with the minimum cumulative mapping distance from the first slice to the last slice based on the minimum mapping distance corresponding to each thickness candidate combination includes: taking the starting thickness as the initial selected thickness of the first slice and setting the cumulative mapping distance of the initial selected thickness of the first slice to zero; traversing each candidate thickness of other slices except the first slice, and for the current candidate thickness of the current slice, calculating the sum of the cumulative mapping distance of each candidate thickness in the previous slice and the minimum mapping distance of the corresponding thickness candidate combination; taking the minimum sum corresponding to the current candidate thickness of the current slice as the cumulative mapping distance of the current candidate thickness, and determining the candidate thickness in the previous slice corresponding to the minimum sum as the associated candidate thickness of the current candidate thickness; starting from the ending thickness of the last slice, backtracking sequentially according to the associated candidate thickness of each candidate thickness of each slice to obtain the selected thickness of each slice, thereby obtaining the thickness sequence.

[0010] Optionally, the above-mentioned determination of the target thickness sequence and the vertex mapping relationship corresponding to the target selected thickness sequence based on the set of candidate mapping relationships between control vertices corresponding to each candidate thickness combination between adjacent slices and the coordinates of each control vertex includes: when there are multiple thickness sequences with the smallest cumulative mapping distance, determining the cumulative concrete volume increment corresponding to each thickness sequence; determining the thickness sequence with the smallest cumulative concrete volume increment as the target thickness sequence; determining the selected thickness of each slice in the target thickness sequence as the target selected thickness of each slice; and determining the best mapping relationship between adjacent slices in the target thickness sequence as the vertex mapping relationship corresponding to the target selected thickness sequence.

[0011] Optionally, determining the cumulative concrete volume increment corresponding to each thickness sequence includes: determining the smaller of the starting thickness and the ending thickness as the reference thickness; for each slice in each thickness sequence, determining the increase in the annular area of ​​the cross section of the slice based on the difference between the target selected thickness and the reference thickness; using the product of the increase in the annular area of ​​the cross section and the construction step distance as the concrete volume increment of the slice; and summing the concrete volume increments of all slices in each thickness sequence to obtain the cumulative concrete volume increment corresponding to each thickness sequence.

[0012] Optionally, the method further includes: obtaining a reference contour line corresponding to the starting point thickness; and offsetting the reference contour line outward at equal intervals according to the candidate thickness of each slice to obtain the cross-sectional contour of each slice.

[0013] Optionally, the above-mentioned method of generating a 3D BIM entity of the tunnel transition section based on the target selected thickness of each slice and the vertex mapping relationship corresponding to the target selected thickness sequence includes: mapping the control vertices on the cross-sectional profile corresponding to the target selected thickness of each slice to 3D coordinates; connecting the control vertices on adjacent slices according to the vertex mapping relationship corresponding to the target selected thickness sequence to generate a 3D mesh wireframe; and performing surface tiling and end cap plate stitching on the 3D mesh wireframe to generate a 3D BIM entity of the tunnel transition section.

[0014] Optionally, the method further includes: issuing an alarm and terminating modeling if the candidate thickness set for a slice is empty.

[0015] This application has the following beneficial effects: The tunnel transition section is divided into multiple slices by construction step distance. Based on the starting thickness, ending thickness, trolley module, and safe driving boundary line, a candidate thickness set is generated for each slice. This ensures that each candidate thickness is a legal position that the steel formwork trolley can directly assemble on site and meets the safe driving boundary line constraints. Then, the mapping relationship between the control vertices of adjacent slices is topologically restricted by preset connection constraints to avoid mesh intersections and facet folding caused by the rotation of adjacent normal planes of curve segments. Subsequently, the target thickness sequence and the corresponding vertex mapping relationship are determined by global optimization with the goal of minimizing the cumulative mapping distance. This ensures that the thickness transition not only meets the module and limit requirements in a single section, but also achieves a smooth transition with the minimum total contour bridging distance across the entire tunnel transition section, taking into account both local manufacturing constraints and global geometric optimization. Finally, the 3D BIM entity generated based on the target selected thickness and the corresponding vertex mapping relationship can be directly used to guide construction, improving the construction feasibility, safety, economy, and digital effectiveness of parametric modeling of the tunnel transition section. Attached Figure Description

[0016] Figure 1 A flowchart illustrating a method for parametric BIM modeling of tunnels based on multi-template library integration, provided as an embodiment of this application; Figure 2 This is a flowchart illustrating another method for parametric BIM modeling of tunnels based on multi-template library integration, provided as an embodiment of this application. Detailed Implementation

[0017] The following description, in conjunction with the accompanying drawings, details a specific scheme for a tunnel parametric BIM modeling method based on multi-template library integration provided in this application.

[0018] Please see Figure 1 The diagram illustrates a flowchart of a tunnel parametric BIM modeling method based on multi-template library integration provided in one embodiment of this application.

[0019] like Figure 1 As shown, the tunnel parametric BIM modeling method based on multi-template library integration includes S101-S105.

[0020] S101. Obtain the starting thickness, ending thickness, trolley module, construction step distance, and safe driving boundary line of the tunnel transition section.

[0021] It should be understood that the tunnel transition section is the section where the lining thickness needs to gradually transition from the standard of the preceding section to the standard of the subsequent section when the horizontal and vertical curves of the tunnel encounter changes in the surrounding rock grade. The starting thickness is the standard lining design thickness used in the preceding section before the mileage of the surrounding rock grade change (i.e., the radial distance from the inner wall of the lining to the outer wall of the lining), and the ending thickness is the standard lining design thickness used in the subsequent section after the mileage of the surrounding rock grade change.

[0022] Optionally, the starting point thickness and ending point thickness can be obtained from the design drawings of the preceding and following road segments.

[0023] The trolley module is the minimum size adjustment constant supported by the steel formwork trolley on the construction site, which is generally a fixed value, such as 50 mm or 100 mm; the construction step distance is the longitudinal physical length of the trolley that is pushed forward for each pour, such as 1 meter or 2 meters.

[0024] The safe driving boundary line is used to characterize the safe driving line for vehicles to pass through the tunnel, which must not be intruded upon by any lining structure inside the tunnel. The safe driving boundary line has fixed length and width dimensions and defines the net space reserved within the tunnel cross section.

[0025] Optionally, the safe driving boundary line can be obtained from the road design specification document corresponding to this project (i.e., the tunnel transition section).

[0026] S102. Divide the tunnel transition section into multiple slices according to the construction step distance, and generate a set of candidate thicknesses that meet the safe driving requirements for each slice based on the starting thickness, ending thickness, trolley module and safe driving boundary line.

[0027] Each slice has multiple control vertices distributed circumferentially on the cross-sectional profile corresponding to each candidate thickness.

[0028] It should be understood that a slice is a discrete cross-section of the tunnel transition section divided at equal intervals according to the construction step distance, and each slice corresponds to an independent local orthogonal plane.

[0029] For example, assuming the length of the tunnel transition section is 20 meters and the construction step distance is 2 meters, then within the tunnel transition section, equidistant mileage coordinates are sampled sequentially at 2-meter step distances to obtain 10 slices, and each slice is indexed and sorted according to the mileage sequence.

[0030] In one optional implementation, an externally imported horizontal and vertical alignment parameter file can be read. The horizontal alignment coordinate sequence (corresponding to X and Y axis coordinates) and vertical profile elevation data (corresponding to Z axis coordinates) stored in the file can be parsed. A three-dimensional centerline coordinate continuous function can be constructed through piecewise fitting, with the route mileage as the independent variable and the three-dimensional coordinates as the dependent variable. This function is used to characterize the continuous geometric shape of the tunnel centerline in three-dimensional space. By inputting any mileage value, the corresponding three-dimensional coordinates and the three-dimensional tangent vector along the route's direction of travel can be calculated. Then, within the tunnel transition section, equidistant mileage coordinates are sampled sequentially according to the construction step distance to generate multiple slices. For each slice, the spatial first derivative of the three-dimensional centerline coordinate continuous function at the current mileage point is calculated to obtain the absolute spatial coordinates of the three-dimensional tangent point and the three-dimensional tangent vector at the current mileage point. Using the absolute spatial coordinates of the tangent point as the local geometric origin, a locally orthogonal normal plane strictly perpendicular to the three-dimensional tangent vector is constructed.

[0031] It should be understood that the candidate thickness set corresponding to a slice is the set of thickness values ​​that can be lining at the slice location. This set includes multiple candidate thicknesses corresponding to the slice location, and each candidate thickness is an integer multiple of the trolley module, thereby ensuring that the generated model size can directly match the industrial assembly gear of the steel formwork trolley.

[0032] In one optional implementation, the orientation step size can be determined based on the polarity of the difference between the endpoint thickness and the starting thickness, as well as the trolley module. Using the starting thickness as the initial value and the endpoint thickness as the target value, the directional step size is used to divide the slice, resulting in multiple initial candidate thicknesses between the initial and target values, and the thickness change increment of each initial candidate thickness. The safety clearance distance of each slice is determined based on the safe driving boundary line. Initial candidate thicknesses whose thickness change increments are greater than the safety clearance distances of each slice are removed from the multiple initial candidate thicknesses, resulting in a set of candidate thicknesses that meet the safe driving requirements for each slice.

[0033] It should be understood that the polarity of the difference is the positive or negative attribute of the difference obtained by subtracting the starting thickness from the ending thickness. If the ending thickness is greater than the starting thickness, the polarity of the difference is positive, indicating that the transition section is in a thickening condition from thin to thick; if the ending thickness is less than the starting thickness, the polarity of the difference is negative, indicating that the transition section is in a thinning condition from thick to thin. The orientation step size is the trolley module step value carrying the above-mentioned polarity of the difference.

[0034] For example, when the trolley module is 50 mm and the difference polarity is positive, the orientation step size is +50 mm; when the difference polarity is negative, the orientation step size is -50 mm.

[0035] It should be understood that the safety clearance distance is the physical red line for the inward thickening and deformation at each slice location. The larger the safety clearance distance, the more available space there is for the inner wall of the lining to expand inward at that slice location; the smaller the safety clearance distance, the more likely that a vehicle intrusion collision risk will be triggered at that location.

[0036] For example, assuming the starting thickness is 300 mm, the ending thickness is 600 mm, and the orientation step size is +50 mm, then the multiple initial candidate thicknesses are 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, and 600 mm, with thickness increments of 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, and 300 mm, respectively. Assuming the safety clearance distance is 230 mm, then the candidate thickness set is 350 mm, 400 mm, 450 mm, and 500 mm.

[0037] Optionally, a baseline contour line corresponding to the starting point thickness can be obtained. The baseline contour line and the safe driving boundary line are synchronously orthogonally projected onto the local orthogonal plane to obtain the projected baseline contour line and the projected safe driving boundary line. On the projected baseline contour line, a series of uniformly distributed discrete sampling points are extracted at equal arc length intervals. At the same time, the closed boundary of the projected safe driving boundary line is obtained. Using the point-to-polygon nearest distance algorithm in computational geometry, the two-dimensional Euclidean distance from each discrete sampling point to the closed boundary of the safe driving boundary line is calculated one by one. All calculation results are summarized into a distance array. A size comparison operation is performed on the array, and the minimum distance value with the absolute smallest value is selected. This minimum value is defined as the safety limit distance of the current slice.

[0038] It should be understood that the reference profile is a standard tunnel inner wall cross-sectional profile bound to the starting thickness, which describes the geometry of the lining inner wall when no thickness offset occurs.

[0039] Alternatively, the baseline profile can be extracted from a tunnel design template library.

[0040] Optionally, the inward widening increment of each initial candidate thickness relative to the starting thickness can be calculated. If the inward widening increment is greater than the safety clearance distance of the slice, it indicates that the initial candidate thickness will cause the lining structure to intrude into the safe driving boundary line, posing a risk of solid collision. Therefore, the initial candidate thickness can be screened out. The remaining initial candidate thicknesses after screening constitute the candidate thickness set that meets the safe driving requirements.

[0041] The above method generates a directional step size by judging the polarity of the difference, and divides the continuous thickness interval into discrete steps with the starting thickness as the initial value and the ending thickness as the target value. This transforms the continuous thickness interval into discrete steps that are integer multiples of the trolley module, which ensures that the generated thickness value is perfectly matched with the mechanical gear of the steel formwork trolley on site. Furthermore, the initial candidate thickness that does not meet the safe driving requirements is screened out by the safety clearance distance. This ensures that the modeling based on the candidate thickness set guarantees the feasibility of on-site construction, avoids the risk of traffic collisions, and thus guarantees the absolute safety of the traffic boundary inside the tunnel.

[0042] It should be understood that the cross-sectional profile is the lining outer wall profile formed by offsetting the baseline profile line outward at equal intervals according to the candidate thickness. The control vertices are discrete points extracted by sampling at equal angles along the circumferential direction of the cross-sectional profile. Each control vertex has a unique sorting index in the circumferential direction, which is used to establish the vertex mapping relationship between adjacent slices in the subsequent process.

[0043] It should be noted that the number of control vertices included in the cross-sectional profile of all slices is the same.

[0044] In one alternative implementation, a reference profile corresponding to the starting point thickness can be obtained; the reference profile is then offset outward at equal intervals according to the candidate thickness of each slice to obtain the cross-sectional profile of each slice.

[0045] It should be understood that since the reference profile is the boundary line of the inner wall of the lining and the cross-sectional profile is the boundary line of the outer wall of the lining, the offset distance is equal to the candidate thickness.

[0046] Specifically, within the local orthogonal plane corresponding to the slice, the reference contour line is offset outwards (i.e., away from the tunnel centerline) at equal intervals along its geometric normal direction according to the candidate thickness. The resulting closed curve is the cross-sectional contour of the slice, which has the same shape as the reference contour line but with a correspondingly reduced radial dimension. For each point on the reference contour line, its offset coordinates are the original coordinates plus the product of the unit normal vector pointing outwards (i.e., away from the tunnel centerline) at that point and the candidate thickness.

[0047] After obtaining the cross-sectional profile, the number of control vertices can be preset (e.g., set to 360 points). For any slice's cross-sectional profile, with the geometric center of the profile as the origin, sampling is performed circumferentially at equal angular intervals within the local orthogonal plane containing the profile, starting from a preset starting position (e.g., directly above), to obtain the 360 ​​control vertices. Simultaneously, the sorting index of each control vertex is recorded sequentially according to the sampling order.

[0048] It should be noted that the cross-sectional profiles corresponding to different thickness candidates have different radii, but the starting orientation and step size during sampling remain consistent. Therefore, the control vertices corresponding to the same sorting index on different cross-sectional profiles have the same relative orientation. Through the above equal-angle sampling operation, each cross-sectional profile corresponding to each candidate thickness on each slice obtains a set of discrete control vertices sorted circumferentially, with a unique sorting index.

[0049] Understandably, the candidate thickness set for a slice may be empty. In the event that the candidate thickness set for a slice is empty, an alarm can be issued and modeling can be terminated.

[0050] It should be understood that if the candidate thickness set of a slice is empty, it means that there is no trolley module gear at the slice location that can meet the thickness transition requirements without encroaching on the travel clearance. This situation usually occurs in extremely narrow areas or areas with severely insufficient clearance margins, indicating that the space conditions of the transition section are insufficient to accommodate the assembly requirements of standard modular trolleys. In this case, an alarm can be issued and the current graph network simulation process can be forcibly stopped to avoid outputting unreasonable or dangerous modeling results.

[0051] S103. Determine the candidate thickness combinations between adjacent slices based on the candidate thickness set of adjacent slices, and determine the candidate mapping relationship set between the control vertices corresponding to each candidate thickness combination that satisfies the preset connection constraint.

[0052] It should be understood that a pair of adjacent slices are divided into preceding slices and subsequent slices according to the slice index. A thickness candidate combination is a pairing relationship formed by a candidate thickness in the preceding slice and a candidate thickness in the subsequent slice. This pairing relationship is used to characterize the possible thickness transition schemes between adjacent slices.

[0053] It should be understood that the preset connection constraint is used to limit the absolute difference between the sorted indices of matching control vertices between adjacent slices to no more than a preset neighborhood tolerance threshold.

[0054] The preset neighborhood tolerance threshold is used to limit the maximum sorting index jump range between preceding and following matching control vertices, representing the maximum number of misaligned grids allowed on the cross-sectional profile by the preceding and following connections. Its value can be determined based on a combination of the total number of control vertices and the curvature of the cross-sectional profile. For example, when the number of control vertices is 360, a value of 3 indicates that a phase offset of approximately 0.83% of the perimeter is allowed between preceding and following cross-sections. This threshold generally does not exceed 1% of the total number of control vertices, but can be appropriately increased to 5-10 in sharp bends.

[0055] In one optional implementation, the sorting index of the control vertices on the cross-sectional profile corresponding to each thickness candidate combination between adjacent slices can be extracted; for all mapping relationships between each control vertex of the preceding slice and each control vertex of the following slice corresponding to each thickness candidate combination between adjacent slices, the cyclic index difference of each vertex pair in each mapping relationship corresponding to each thickness candidate combination is determined; vertex pairs with cyclic index differences greater than the preset neighborhood tolerance threshold are identified as abnormal vertex pairs; mapping relationships containing abnormal vertex pairs are filtered out from all mapping relationships to obtain a set of candidate mapping relationships.

[0056] The mapping relationship refers to the one-to-one pairing scheme between all control vertices on the cross-sectional profile of the candidate thickness of the preceding slice and all control vertices on the cross-sectional profile of the candidate thickness of the subsequent slice. That is, a set of mapping relationships includes multiple vertex pairings equal to the number of control vertices in the preceding slice, and each control vertex of the preceding slice appears exactly once in each set of mapping relationships with each control vertex of the subsequent slice.

[0057] For example, assuming that the preorder slice and the postorder slice each have 360 ​​control vertices, then a set of mappings contains 360 vertex pairs.

[0058] It should be understood that for a certain thickness candidate combination between adjacent slices, there are multiple possible one-to-one pairing schemes between the control vertices of the preceding slice and the control vertices of the following slice, i.e., multiple mapping relationships. For each mapping relationship under the thickness candidate combination, each vertex pairing is traversed sequentially, and the sorted indexes of the control vertices of the preceding slice and the following slice involved in the vertex pairing are extracted. The cyclic index difference corresponding to the vertex pairing is then calculated.

[0059] Since the control vertices are distributed in a closed loop on the cross-sectional profile, the absolute value of the difference between the two sorting indices and the absolute value of the difference between the absolute value of the difference and the total number of control vertices can be calculated separately, and the minimum of the two values ​​can be determined as the cyclic index difference.

[0060] Optionally, the above calculation is repeated for all vertex pairs in the group of mappings to determine the set of cyclic index differences corresponding to each vertex pair in the group of mappings.

[0061] Understandably, when the cyclic index difference of a vertex pair is greater than the preset neighborhood tolerance threshold, it indicates that there are pairs in the mapping relationship to which the vertex pair belongs that have lines that will cross the internal region of the cross section, which will lead to large-scale mesh intersections. In this case, the vertex pair can be identified as an abnormal vertex pair, and the mapping relationship containing the abnormal vertex pair can be screened out as a whole. If the cyclic index difference of all vertex pairs in a mapping relationship is not greater than the preset neighborhood tolerance threshold, it indicates that all vertex pairs in the mapping relationship belong to the safe adjacent region on the circumferential topology, and the mapping relationship should be retained.

[0062] In one alternative implementation, for a given thickness candidate combination, a two-dimensional weight matrix can be constructed to carry all possible single vertex pairings under that thickness candidate combination. The rows of this matrix correspond to the control vertices of the preceding slice, and the columns correspond to the control vertices of the following slice. Each element in the matrix corresponds to a single pairing relationship between a pair of control vertices, and its initial value is the three-dimensional Euclidean distance of that pair. When traversing each element of this matrix, the preceding control vertex sorting index and the following control vertex sorting index that generated the element can be extracted, and the absolute value of the difference between their indices can be calculated. If this absolute value is greater than a preset neighborhood tolerance threshold, the value of the matrix element is set to a blocking value (e.g., the largest floating-point number allowed by computer memory or infinity), thereby removing the single pairing from the candidate mapping relationship set. After traversal processing, the single pairs corresponding to the elements in the two-dimensional weight matrix that are not set to blocking values ​​constitute the candidate single pairing set. Subsequently, when performing one-to-one surjective matching on this two-dimensional weight matrix, the algorithm automatically bypasses the blocked single pairs, and the output mapping relationship must satisfy the preset connection constraints.

[0063] The above method extracts the sorted index of the control vertices distributed along the circumferential direction, calculates the cyclic index difference of all possible mapping relationships, and quantifies the degree of deviation of vertex pairing in the cyclic direction. By using a preset neighborhood tolerance threshold, mapping relationships that exceed the index neighborhood range are rigidly screened out, so that the remaining mapping relationships are all legal matches within the local neighborhood. This eliminates the risk of geometric intersections and folds when generating 3D solid meshes and ensures the topological correctness of the subsequently generated 3D BIM solid surfaces.

[0064] S104. Based on the set of candidate mapping relationships between control vertices corresponding to each candidate thickness combination between adjacent slices and the coordinates of each control vertex, determine the target thickness sequence and the vertex mapping relationship corresponding to the selected target thickness sequence.

[0065] The target thickness sequence includes the target selected thickness for each slice.

[0066] It should be understood that the target thickness sequence is the optimal combination of thickness values ​​that runs through all slices and continuously transitions from the starting thickness to the ending thickness. By calculating the distance between control vertices using the coordinates of each control vertex, the target thickness sequence with the minimum cumulative mapping distance can be obtained, thus ensuring the smoothness of the 3D solid surface.

[0067] It should be understood that the vertex mapping relationship corresponding to the selected thickness sequence is the optimal mapping relationship between the control vertices of adjacent slices, that is, the mapping relationship that minimizes the cumulative mapping distance.

[0068] S105. Generate a 3D BIM entity of the tunnel transition section based on the target selected thickness of each slice and the vertex mapping relationship corresponding to the target selected thickness sequence.

[0069] It should be understood that a 3D BIM entity is a digital tunnel transition section model with a closed geometric space that can be directly used for construction material cutting and quantity statistics.

[0070] In one alternative implementation, the control vertices on the cross-sectional profile corresponding to the target selected thickness of each slice can be mapped to three-dimensional coordinates; the control vertices on adjacent slices can be connected according to the vertex mapping relationship corresponding to the target selected thickness sequence to generate a three-dimensional mesh wireframe; surface tiling and end cap plate stitching can be performed on the three-dimensional mesh wireframe to generate a three-dimensional BIM entity of the tunnel transition section.

[0071] Optionally, a coordinate transformation matrix is ​​established, using the local geometric origin of the slice as a reference, to transform from a two-dimensional local orthogonal plane to a three-dimensional coordinate system. Through this matrix transformation, the two-dimensional local coordinates of each control vertex on the cross-sectional profile are mapped to three-dimensional coordinates in the three-dimensional coordinate system.

[0072] Optionally, repeating the above mapping operation on all slices can generate multiple groups of scattered points aligned end to end in three-dimensional space, forming the geometric skeleton points of the transition section of the tunnel inner wall.

[0073] Optionally, based on the vertex mapping relationship corresponding to the selected thickness sequence, the vertex mapping relationship between all adjacent slices is traversed, and the paired control vertices between adjacent slices are connected to generate a set of regular and ordered skeleton line network between adjacent slices. This skeleton line network is the three-dimensional mesh wireframe.

[0074] During the surface laying phase, the built-in 3D polygon surface construction command of the BIM software can be invoked. The system uses the quadrilateral holes formed by the interlacing of adjacent lines in the 3D mesh frame as boundary conditions, and lays and fills each hole to generate a continuous digital mesh surface shell. This surface shell covers the side area of ​​the tunnel transition section, but the beginning and end are still open and have not yet formed a closed entity with volume.

[0075] During the initial and final cover plate stitching stage, the first and last cross-sections of the first slice and the last slice are located. Using the target selection thicknesses on these cross-sections, two closed 2D polygonal cover plates are generated. Subsequently, the hollow mesh surface shell is watertightly joined to the initial and final cover plates using the BIM software's built-in boundary topology stitching command. This stitching operation topologically matches and merges the open boundaries of the surface shell with the closed boundaries of the cover plates, ensuring no cracks, overlaps, or open edges at the joint, ultimately forming a 3D BIM transition section entity with a sealed geometric space.

[0076] In the methods provided in S101-S105 above, the tunnel transition section is divided into multiple slices by the construction step distance. Based on the starting thickness, ending thickness, trolley module, and safe driving boundary line, a candidate thickness set corresponding to each slice is generated. This ensures that each candidate thickness is a legal position that the steel formwork trolley can directly assemble on site and meets the safe driving boundary line constraints. Then, the mapping relationship between the control vertices of adjacent slices is topologically restricted by preset connection constraints to avoid mesh intersection and facet folding caused by the rotation of adjacent normal planes of curve segments. Afterward, the target thickness sequence and the corresponding vertex mapping relationship are determined by global optimization with the goal of minimizing the cumulative mapping distance. This makes the thickness transition not only meet the module and limit requirements in a single section, but also achieves a smooth transition with the minimum total distance of contour bridging on the entire tunnel transition section, taking into account both local manufacturing constraints and global geometric optimization. Finally, the 3D BIM entity generated based on the target selected thickness and the corresponding vertex mapping relationship can be directly used to guide construction, improving the construction feasibility, safety, economy, and digital effectiveness of parametric modeling of the tunnel transition section.

[0077] Combination Figure 1 ,like Figure 2 As shown, the above S104 can be implemented through S201-S204.

[0078] S201. Based on the coordinates of the control vertex, determine the total matching distance corresponding to each candidate mapping relationship in each candidate mapping relationship set.

[0079] It should be understood that the total matching distance corresponding to a candidate mapping relationship is the sum of the spatial connection distances between all vertex pairs in the candidate mapping relationship. It is used to characterize the sum of the physical lengths of all corresponding connections between the cross-sectional contours of adjacent slices under the candidate mapping relationship. The larger the value, the more significant the spatial distortion of the contour transition.

[0080] Optionally, since the two-dimensional coordinates of the control vertices have been mapped to three-dimensional coordinates in S102, the Euclidean distance between each pair of vertex pairs can be determined based on the three-dimensional coordinates of the control vertices. The Euclidean distances between all vertex pairs can be summed to obtain the total matching distance corresponding to the candidate mapping relationship.

[0081] S202. Determine the candidate mapping relationship with the smallest total matching distance in each candidate mapping relationship set as the best mapping relationship for the corresponding thickness candidate combination, and determine the total matching distance corresponding to the best mapping relationship as the minimum mapping distance.

[0082] It should be understood that the smaller the total matching distance, the shorter and more natural the connection between control vertices on adjacent slices is in space. This avoids wrinkles, folds, or self-intersections caused by long-distance oblique connections or cross-regional connections, resulting in a smoother and more continuous surface of the generated 3D model. Therefore, the candidate mapping relationship with the smallest total matching distance can be determined as the optimal mapping relationship.

[0083] Optionally, the constructed two-dimensional weight matrix can be input into the Hungarian algorithm solver to obtain the minimum total matching distance under the preset connection constraints, and the optimal mapping relationship that minimizes the total matching distance.

[0084] S203. Based on the minimum mapping distance corresponding to each thickness candidate combination, determine the thickness sequence with the minimum cumulative mapping distance from the first slice to the last slice.

[0085] It should be understood that the thickness sequence can be interpreted as the thickness path that runs through all slices, continuously transitioning from the starting thickness to the ending thickness with the minimum cumulative mapping distance. The cumulative mapping distance is the sum of the total matching distances between any two adjacent slices in all slices.

[0086] In one optional implementation, the starting thickness is used as the initial selected thickness of the first slice, and the cumulative mapping distance of the initial selected thickness of the first slice is set to zero. For each candidate thickness of the other slices, the process is traversed. For the current candidate thickness of the current slice, the sum of the cumulative mapping distance of each candidate thickness in the previous slice and the minimum mapping distance of the corresponding thickness candidate combination is calculated. The minimum sum corresponding to the current candidate thickness of the current slice is used as the cumulative mapping distance of the current candidate thickness, and the candidate thickness in the previous slice corresponding to the minimum sum is determined as the associated candidate thickness of the current candidate thickness. Starting from the ending thickness of the last slice, the process is reversed sequentially according to the associated candidate thickness of each candidate thickness of each slice to obtain the selected thickness of each slice, thus obtaining the thickness sequence.

[0087] It should be understood that since the starting thickness is fixed, the initial selected thickness of the first slice can be determined as the starting thickness. Since this starting thickness is the thickness of the first slice, the cumulative mapping distance of the initial selected thickness of the first slice should be zero.

[0088] It should be noted that the cumulative mapping distance of a slice is the sum of the mapping distances from the first slice to that slice.

[0089] During the traversal, you can proceed layer by layer from front to back according to the slice number.

[0090] For example, for each candidate thickness of the second slice (assuming it includes candidate thickness 1 and candidate thickness 2), the cumulative mapping distance 1 of candidate thickness 1 is: 0 plus the minimum mapping distance between candidate thickness 1 and the starting thickness, and the cumulative mapping distance 2 of candidate thickness 2 is: 0 plus the minimum mapping distance between candidate thickness 2 and the starting thickness. Since there is only one initial candidate thickness in the first slice, the associated candidate thickness of each candidate thickness in the second slice is the initial candidate thickness. For each candidate thickness of the third slice (assuming it includes candidate thickness 3), the cumulative mapping distance 3 between candidate thickness 3 and candidate thickness 1 (i.e., the cumulative mapping distance 1 plus the minimum mapping distance between candidate thickness 3 and candidate thickness 1) and the cumulative mapping distance 4 between candidate thickness 3 and candidate thickness 2 (i.e., the cumulative mapping distance 2 plus the minimum mapping distance between candidate thickness 3 and candidate thickness 2) are calculated respectively. If the cumulative mapping distance 3 is less than the cumulative mapping distance 4, then the associated candidate thickness of candidate thickness 3 is candidate thickness 1.

[0091] It should be understood that the cumulative mapping distance of 3 is the minimum cumulative mapping distance between the first slice and the third slice, i.e., the cumulative mapping distance of 3. And so on, the minimum cumulative mapping distance between the first slice and the last slice is obtained. This minimum cumulative mapping distance represents the minimum cumulative mapping distance from the first slice to the last slice.

[0092] After traversing all candidate thicknesses for all slices, we obtain the associated candidate thickness for each candidate thickness in each slice. At this point, we can take the endpoint thickness as the endpoint and start from that endpoint, backtracking the corresponding associated candidate thicknesses sequentially until we reach the starting thickness of the first slice, thus obtaining the thickness sequence from the first slice to the last slice.

[0093] It should be noted that in the previous slice, there may be multiple candidate thicknesses with the same minimum connection cost. In this case, there may be multiple associated candidate thicknesses, and consequently, there may be multiple thickness sequences obtained from subsequent backtracking.

[0094] Understandably, this chain-like backtracking reading allows us to extract the thickness sequence that spans all slices and has the smallest cumulative mapping distance.

[0095] S204. When there is only one thickness sequence with the smallest cumulative mapping distance, the thickness sequence is determined as the target thickness sequence, and the best mapping relationship between adjacent slices in the target thickness sequence is determined as the vertex mapping relationship corresponding to the target selected thickness sequence.

[0096] It is understandable that if there is only one thickness sequence that minimizes the cumulative mapping distance, then the thickness sequence can be directly determined as the target thickness sequence, and the candidate thickness corresponding to each slice position in the sequence can be determined as the target selected thickness of the slice. The best mapping relationship between adjacent slices in the target thickness sequence can be determined as the vertex mapping relationship.

[0097] In another alternative implementation, when there are multiple thickness sequences with the smallest cumulative mapping distance, the cumulative concrete volume increment corresponding to each thickness sequence can be determined; the thickness sequence with the smallest cumulative concrete volume increment is determined as the target thickness sequence, the selected thickness of each slice in the target thickness sequence is determined as the target selected thickness of each slice, and the optimal mapping relationship between adjacent slices in the target thickness sequence is determined as the vertex mapping relationship corresponding to the target selected thickness sequence.

[0098] Understandably, when there are multiple thickness sequences with the smallest cumulative mapping distance, the cumulative mapping distance alone cannot distinguish the quality of these multiple thickness sequences. In this case, cost indicators can be introduced for secondary screening.

[0099] It should be understood that the cumulative concrete volume increment is the total volume of concrete backfill that needs to be added compared to the reference thickness. The smaller the total concrete backfill volume, the lower the cost and the higher the economic efficiency. Therefore, the thickness sequence with the smallest cumulative concrete volume increment can be determined as the target thickness sequence.

[0100] Optionally, the smaller of the starting thickness and the ending thickness is determined as the reference thickness; for each slice in each thickness sequence, the increase in the annular area of ​​the cross section of the slice is determined based on the difference between the target selected thickness and the reference thickness; the product of the increase in the annular area of ​​the cross section and the construction step distance is used as the concrete volume increment of the slice; the concrete volume increments of all slices in each thickness sequence are summed to obtain the cumulative concrete volume increment corresponding to each thickness sequence.

[0101] It should be understood that the increase in the annular area of ​​the cross section is the additional area of ​​the annular region of the lining cross section compared to the reference thickness after the current slice adopts the target selected thickness.

[0102] Optionally, the difference between the target thickness and the reference thickness can be calculated first to obtain the thickness widening increment. Due to the difference in curvature between the inner and outer sides of the tunnel in the curved section, the thickness widening increment is not uniformly distributed on the same circumference, but is offset outward along the normal direction. Therefore, the additional cross-sectional area is an irregular ring. Combining the difference between the radius of curvature of the tunnel centerline at this slice location and the difference in arc length between the inner and outer sides of the lining, the thickness widening increment is converted into the increase in the two-dimensional annular cross-sectional area through geometric area formulas or integral calculations.

[0103] Optionally, for approximately straight road sections with a large radius of curvature (e.g., a radius of curvature greater than 500 meters), the rectangular ring approximation formula can be used to calculate the increase in the cross-sectional annular area as the product of the thickness widening increment and the average perimeter of the reference contour line. For sharp bends with a small radius of curvature (e.g., a radius of curvature less than or equal to 500 meters), an integral method can be used to divide the reference contour line into micro-elements at each 1-degree central angle or each 0.1-meter arc length. The cross-sectional annular area micro-element at each micro-element is equal to the product of the arc length increment after normal offset at that point and the thickness widening increment. The increase in the cross-sectional annular area is obtained by arithmetic summation of the areas of all micro-elements.

[0104] It should be understood that the construction step distance is used to characterize the longitudinal length benchmark, extending the cross-sectional deformation of a single slice into a volume increment in three-dimensional space. Multiplying the increase in the annular area of ​​the cross-section by the construction step distance can convert the two-dimensional cross-sectional area increment into the specific three-dimensional material volume of the current trolley's advance segment, that is, the additional concrete backfill volume caused by the slice at the target selected thickness.

[0105] Optionally, traversal is performed along all slices covered by the thickness sequence, the concrete volume increment calculated for each slice at the target selected thickness is extracted, and all concrete volume increments are summed to obtain the cumulative concrete volume increment of the entire tunnel transition section corresponding to the thickness sequence.

[0106] The methods provided in S201-S204 above quantify the spatial distortion cost of different thickness transition schemes between adjacent slices by determining the total matching distance and the minimum mapping distance; by calculating the cumulative mapping distance layer by layer and recording the associated candidate thickness, the computational complexity of global optimization is reduced by using the principle of dynamic programming; by backtracking backward to uniquely extract the thickness sequence from the endpoint thickness, the continuity and smoothness of the thickness transition are ensured; and while ensuring the minimum cumulative mapping distance, the increase in concrete volume is further measured, avoiding material waste and improving the economy of construction.

[0107] It should be noted that the order of the embodiments described above 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.

[0108] 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 parametric BIM modeling method for tunnels based on multi-template library integration, characterized in that, include: Obtain the starting thickness, ending thickness, trolley module, construction step distance, and safe driving boundary line of the tunnel transition section; The tunnel transition section is divided into multiple slices according to the construction step distance. Based on the starting thickness, ending thickness, trolley module and safe driving boundary line, a set of candidate thicknesses that meet the safe driving requirements is generated for each slice. Each candidate thickness of each slice has multiple control vertices distributed circumferentially on the cross-sectional profile. Based on the candidate thickness set of adjacent slices, determine each candidate thickness combination between adjacent slices, and determine the set of candidate mapping relationships between the control vertices corresponding to each candidate thickness combination that satisfy the preset connection constraints; Based on the set of candidate mapping relationships between control vertices corresponding to each thickness candidate combination between adjacent slices and the coordinates of each control vertex, the target thickness sequence and the vertex mapping relationship corresponding to the target selected thickness sequence are determined, wherein the target thickness sequence includes the target selected thickness of each slice; Based on the target selected thickness of each slice and the vertex mapping relationship corresponding to the target selected thickness sequence, a 3D BIM entity of the tunnel transition section is generated.

2. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 1, characterized in that, The process involves generating a candidate thickness set for each slice that meets the safety driving requirements based on the starting thickness, ending thickness, trolley module, and safe driving boundary line. This set includes: The orientation step size is determined based on the polarity of the difference between the end-point thickness and the starting-point thickness, as well as the trolley module. Using the starting point thickness as the initial value and the ending point thickness as the target value, and dividing the area by the directional step size, we obtain multiple initial candidate thicknesses between the initial value and the target value, as well as the thickness change increment of each initial candidate thickness. Determine the safe clearance distance for each segment based on the safe driving boundary line; From multiple initial candidate thicknesses, the initial candidate thicknesses whose thickness change increment is greater than the safety clearance distance of each slice are removed to obtain the candidate thickness set that meets the safe driving requirements for each slice.

3. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 1, characterized in that, The preset connection constraint is used to limit the absolute difference between the sorting indices of matching control vertices between adjacent slices to no more than a preset neighborhood tolerance threshold. The step of determining each candidate thickness combination between adjacent slices based on the candidate thickness set of adjacent slices, and determining the set of candidate mapping relationships between control vertices corresponding to each candidate thickness combination that satisfy the preset connection constraint, includes: Extract the sorted index of the control vertices on the cross-sectional profile corresponding to each candidate thickness combination between adjacent slices; For each thickness candidate combination between adjacent slices, determine the cyclic index difference of each vertex pair in each set of mapping relationships corresponding to each vertex pair in each set of mapping relationships. Each set of mapping relationships includes multiple vertex pairs equal to the number of control vertices in the previous slice. Vertex pairings whose cyclic index difference is greater than the preset neighborhood tolerance threshold are identified as abnormal vertex pairings. The candidate mapping set is obtained by filtering out mappings containing abnormal vertex pairings from all mappings.

4. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 1, characterized in that, The step of determining the target thickness sequence and the vertex mapping relationship corresponding to the selected target thickness sequence based on the set of candidate mapping relationships between control vertices corresponding to each candidate thickness combination between adjacent slices and the coordinates of each control vertex includes: Based on the coordinates of the control vertex, determine the total matching distance for each candidate mapping relationship in each candidate mapping relationship set; The candidate mapping relationship with the smallest total matching distance in each candidate mapping relationship set is determined as the best mapping relationship for the corresponding thickness candidate combination, and the total matching distance corresponding to the best mapping relationship is determined as the minimum mapping distance; Based on the minimum mapping distance corresponding to each candidate thickness combination, determine the thickness sequence with the minimum cumulative mapping distance from the first slice to the last slice; If there is only one thickness sequence with the smallest cumulative mapping distance, the thickness sequence is determined as the target thickness sequence, and the best mapping relationship between adjacent slices in the target thickness sequence is determined as the vertex mapping relationship corresponding to the target selected thickness sequence.

5. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 4, characterized in that, The step of determining the thickness sequence with the smallest cumulative mapping distance from the first slice to the last slice based on the minimum mapping distance corresponding to each candidate thickness combination includes: The starting thickness is used as the initial selected thickness of the first slice, and the cumulative mapping distance of the initial selected thickness of the first slice is set to zero. For each candidate thickness of slices other than the first slice, traverse the slices. For the current candidate thickness of the current slice, calculate the sum of the cumulative mapping distance of each candidate thickness in the previous slice and the minimum mapping distance of the corresponding thickness candidate combination. The minimum sum corresponding to the current candidate thickness of the current slice is taken as the cumulative mapping distance of the current candidate thickness, and the candidate thickness in the previous slice corresponding to the minimum sum is determined as the associated candidate thickness of the current candidate thickness. Starting from the final thickness of the last slice, the process backtracks sequentially based on the associated candidate thicknesses of each candidate thickness in each slice to obtain the selected thickness of each slice, thus obtaining the thickness sequence.

6. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 4, characterized in that, The step of determining the target thickness sequence and the vertex mapping relationship corresponding to the selected target thickness sequence based on the set of candidate mapping relationships between control vertices corresponding to each candidate thickness combination between adjacent slices and the coordinates of each control vertex includes: When there are multiple thickness sequences with the smallest cumulative mapping distance, determine the cumulative concrete volume increment corresponding to each thickness sequence; The thickness sequence with the smallest cumulative increase in concrete volume is determined as the target thickness sequence. The selected thickness of each slice in the target thickness sequence is determined as the target selected thickness of each slice. The optimal mapping relationship between adjacent slices in the target thickness sequence is determined as the vertex mapping relationship corresponding to the target selected thickness sequence.

7. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 6, characterized in that, Determining the cumulative concrete volume increment corresponding to each thickness sequence includes: The smaller value between the starting thickness and the ending thickness is determined as the reference thickness; For each slice in each thickness sequence, the increase in the cross-sectional annular area of ​​the slice is determined based on the difference between the target selected thickness and the reference thickness of the slice. The product of the increase in the annular area of ​​the cross section and the construction step distance is taken as the increase in the concrete volume of the slice. The cumulative concrete volume increment of each thickness sequence is obtained by summing the concrete volume increment of all slices in each thickness sequence.

8. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 1, characterized in that, The method further includes: Obtain the baseline profile corresponding to the starting thickness; The baseline profile is offset outward at equal intervals based on the candidate thickness of each slice to obtain the cross-sectional profile of each slice.

9. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 8, characterized in that, The step of generating a 3D BIM entity for the tunnel transition section based on the target selected thickness of each slice and the vertex mapping relationship corresponding to the target selected thickness sequence includes: Map the control vertices on the cross-sectional profile corresponding to the target selected thickness of each slice to three-dimensional coordinates; Connect the control vertices on adjacent slices according to the vertex mapping relationship corresponding to the selected thickness sequence to generate a 3D mesh wireframe. Perform surface tiling and end cap plate stitching on the 3D mesh wireframe to generate a 3D BIM entity of the tunnel transition section.

10. The tunnel parametric BIM modeling method based on multi-template library integration according to claim 1, characterized in that, The method further includes: If the candidate thickness set for a slice is empty, issue an alarm and terminate the modeling process.

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