Chimney outer tube formwork deconstruction and real-time positioning construction method based on BIM technology

Abstract

The present application relates to chimney digital construction technology field, disclose a chimney outer tube formwork deconstruction and real-time positioning construction method based on BIM technology, including: obtaining BIM construction dataset, establish the continuous function relationship of chimney outer tube, generate chimney outer tube three-dimensional entity model, divide construction section and generate three-dimensional positioning grid, after checking output chimney outer tube three-dimensional entity model and three-dimensional positioning grid;Positioning the section to be constructed, extracting the key size to calculate the section circumference and the gradient of the section, deconstructing the section surface and the template specification library matching to generate the parameter list;Extract the theoretical space coordinates to form the theoretical positioning point set;Obtain the site measured point to calculate the radial deviation and the elevation deviation, output warning information and correction positioning data when exceeding the standard;After completion, obtain the chimney completion point cloud data, iterative fitting and local correction and archive construction information, output the completion version of chimney outer tube three-dimensional entity model and whole cycle construction information database, improve the construction precision and efficiency of chimney outer tube.

Description

Technical Field

[0001] This invention relates to the field of digital construction technology for chimneys, specifically to a construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology. Background Technology

[0002] Most chimney outer casings feature gradually curved surface structures. Traditional construction relies on 2D drawings and manual surveying and layout, making it difficult to guarantee the accuracy of formwork assembly, disassembly, and positioning. This often leads to problems such as misaligned joints, poor arc transitions, and grout leakage. In high-altitude operations, formwork compaction and positioning rely heavily on experience-based judgment, lacking visual guidance and real-time verification, making verticality and radius control difficult. Furthermore, the lack of digital coordination in formwork turnover and dismantling results in low efficiency and high safety risks. Existing technologies do not integrate BIM models with on-site positioning, failing to accurately achieve formwork disassembly, dynamic matching, and real-time correction, thus failing to meet the high-precision and high-efficiency construction requirements of chimneys.

[0003] Chinese Patent CN118965686A discloses a BIM-based slipform construction method for a chimney with a variable diameter outer circle and inner square shape. The method includes: modeling and designing the slipform equipment using BIM technology and performing calculations; conducting no-load and load tests before construction; calculating the slipforming speed and concrete demolding strength using the BIM system; performing initial slipforming based on the BIM calculation results and feeding the initial slipforming test results back to the BIM system for verification; debugging and various checks; normal slipforming; and stopping and dismantling the slipform equipment after slipforming is completed. Compared with existing technologies, this invention designs slipform equipment for chimneys with an outer circle and inner square shape, achieving slipform construction of the chimney through the synchronous lifting of the inner and outer ring lifting platforms. BIM technology enables coordination of data and information among project participants, reducing construction costs and simplifying the synchronous construction and coordination of the outer concrete structure and the inner concrete platform. Furthermore, calculations can help identify potential problems before actual construction.

[0004] Although there is an existing BIM-based slipform construction method for variable-diameter chimneys with an outer circle and inner square shape, which achieves safe slipform construction and construction coordination optimization of variable-diameter chimneys with an outer circle and inner square shape through BIM modeling and verification, synchronous lifting of inner and outer platforms, and control of slipforming speed and demolding strength, the existing chimney slipform construction technology still relies on manual calculation. This is not only cumbersome and time-consuming, but also prone to human error, affecting construction safety and accuracy. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a construction method for chimney outer cylinder template deconstruction and real-time positioning based on BIM technology. This method solves the problems of cumbersome template layout, high layout loss, poor positioning accuracy, and difficulty in real-time control of construction deviations in traditional chimney construction. By using elevation-driven parametric modeling, intelligent template layout, three-dimensional positioning point generation, and on-site measurement and correction, the method improves construction efficiency and forming quality, and constructs a traceable full-cycle construction information database.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology includes:

[0008] Key geometric and process parameters are extracted from chimney construction-related documents and preprocessed to generate a BIM construction dataset.

[0009] Using elevation as the driving variable, a continuous functional relationship between the outer diameter, inner diameter, and slope of the chimney outer cylinder is established. A three-dimensional solid model of the chimney outer cylinder is generated through parametric modeling. Construction segments are divided and a three-dimensional positioning mesh is generated. After verification, the three-dimensional solid model of the chimney outer cylinder and the three-dimensional positioning mesh are output as theoretical benchmarks.

[0010] The system locates the construction segment in real time, extracts the key dimensions of the corresponding construction segment from the 3D solid model of the chimney outer cylinder, calculates the segment perimeter and taper gradient, deconstructs the surface of the corresponding construction segment and matches it with the preset template specification library to generate a parameter list, and extracts the theoretical spatial coordinates of template corner points and screw hole positions from the 3D positioning mesh to form a theoretical positioning point set.

[0011] During construction, the radial and elevation deviations are calculated by combining on-site measured points with theoretical positioning point sets. When deviations exceed the limits, early warning information and correction positioning data are output. After completion, the chimney as-built point cloud data is acquired for iterative fitting and local correction, and the construction information is archived. The as-built chimney outer cylinder three-dimensional solid model and the full-cycle construction information database are output.

[0012] Specifically, the steps for generating a 3D solid model of the chimney's outer casing include:

[0013] The data parsing module of the BIM platform is used to extract and verify the structured BIM construction dataset.

[0014] Using elevation as the driving variable, a continuous functional relationship between the outer diameter, inner diameter, slope, and elevation of the chimney outer casing is established.

[0015] Based on continuous function relationships, the parametric modeling algorithm built into the BIM platform generates a three-dimensional solid model of the chimney outer cylinder, including an input layer, a feature extraction layer, a parameter optimization layer, and an output layer.

[0016] The input layer is used to receive the BIM construction dataset and continuous function relationship parameters after being verified by the data parsing module;

[0017] The feature extraction layer is used to extract key features of the chimney outer casing from the verified BIM construction dataset and continuous function relationships, and couple them with the continuous function relationships to filter out the core parameters required for generating the three-dimensional solid model of the chimney outer casing.

[0018] Specifically, the steps for generating a 3D solid model of the chimney outer casing also include:

[0019] The parameter optimization layer is used to combine construction specification parameters to optimize the linear relationship between the inner and outer diameters of the chimney in a continuous functional relationship.

[0020] The decreasing coefficient and inner and outer diameter parameters are dynamically optimized, and the range of parameter values ​​is constrained.

[0021] The output layer is used to output the initial 3D solid model and parameter records of the outer casing of the chimney.

[0022] Using the design parameters in the BIM construction dataset as the core training samples and combining historical chimney construction model data as auxiliary samples, a model training dataset is constructed.

[0023] The sum of squared deviations between the model dimensions and the design values ​​was used as the loss function, and the Adam optimizer was combined to iteratively train the 3D solid model of the chimney outer casing.

[0024] During training, the parameter validation logic of the parameter optimization layer is invoked in each iteration to monitor the model parameter deviation in real time.

[0025] After training, the validated BIM construction dataset and elevation parameters are input in real time. Through function calculation and feature matching, the initial three-dimensional solid model of the chimney outer cylinder and the corresponding function relationship parameter package are output.

[0026] Specifically, the steps for outputting the three-dimensional solid model and three-dimensional positioning mesh of the chimney outer casing as the theoretical benchmark include:

[0027] Based on the initial three-dimensional solid model of the outer casing of the chimney, the corresponding function relationship parameter package, and the requirements for dividing the construction segments, the construction segments are divided along the height of the chimney.

[0028] Generate an initial three-dimensional positioning mesh for each construction segment, associate the elevation, inner and outer diameters and slope parameters of the corresponding segment, and output a three-dimensional model of the chimney outer cylinder with construction segment division and the initial three-dimensional positioning mesh.

[0029] Calculate the dimensional deviation, call the dynamic optimization logic of the parameter optimization layer for the parts with excessive dimensional deviation, and correct the parameters of the chimney outer cylinder 3D model divided by construction segments based on the continuous function relationship to obtain the corrected 3D positioning mesh.

[0030] Perform collision checks to identify interference conflicts, adjust the node coordinates of the 3D positioning mesh to eliminate interference conflicts, and verify and confirm the results again after adjustment;

[0031] Integrate and correct the 3D model of the chimney outer casing, the 3D positioning mesh, and all parameter records, verify the data consistency, and output the 3D solid model of the chimney outer casing and the 3D positioning mesh as the theoretical benchmark.

[0032] Specifically, the steps for calculating the segment perimeter and the convergence gradient include:

[0033] For each construction segment, using the bottom and top elevations of the current construction segment as boundaries, the outer cylinder surface patch of the current construction segment is extracted from the three-dimensional solid model of the chimney outer cylinder, which serves as the theoretical benchmark, and parameterized. domain;

[0034] Read the coordinates of all grid nodes corresponding to the bottom elevation of the current construction segment, and take the circumferential midline of all grid node coordinates as the reference direction for the expansion of the fan-shaped ring.

[0035] The bottom outer diameter, top outer diameter, and average radius of the current construction segment are calculated using a continuous function relationship expression, and the upper arc length, lower arc length, and radial height of the fan-shaped ring are also calculated.

[0036] The average value of the upper and lower arc lengths is used to obtain the perimeter of the current construction segment. The tapering gradient of the current construction segment is calculated based on the bottom outer diameter, top outer diameter, and segment height.

[0037] Specifically, the steps for generating the parameter list include:

[0038] Using a fan-shaped annular zone as the raw material area, a two-dimensional matrix nesting algorithm is used for template arrangement. Multi-objective particle swarm optimization iteratively searches for the optimal combination, outputting a list of standard templates required to cover the fan-shaped annular zone and... Position coordinates within the domain;

[0039] For the remaining areas not covered by the standard template, generate the geometric contour of the non-standard template based on the boundary shape, and calculate the cutting dimensions of the non-standard template;

[0040] The standard and non-standard templates are inversely mapped back to a 3D surface for virtual splicing and alignment detection.

[0041] If the maximum gap between adjacent template boundaries is greater than the preset gap threshold or the misalignment is greater than the preset misalignment threshold, the alignment test is deemed to have failed. The template positions are rotated or swapped and the test is repeated until the seam rule is met.

[0042] Summarize the list of standard templates, the cutting dimensions of non-standard templates, and the position coordinates of each template to generate a parameter list.

[0043] Specifically, the steps for forming the theoretical location point set include:

[0044] Place each template in The corner points in the domain are converted into three-dimensional spatial coordinates. For surfaces that cannot be analytically represented, bilinear interpolation is used to calculate the three-dimensional spatial coordinates.

[0045] Traverse the 3D positioning grid and calculate the Euclidean distance using 3D spatial coordinates;

[0046] If the Euclidean distance is less than or equal to the preset distance limit, the node attributes are directly inherited; otherwise, the theoretical coordinates of the corner points are calculated and marked as encrypted positioning points.

[0047] Based on the relative layout of the screw holes, calculate the parameter coordinates of all hole positions and map them onto a three-dimensional surface. Expand along the surface normal vector to obtain the spatial coordinates of the actual screw piercing point.

[0048] The corner point set and screw hole position set are obtained and combined into the original theoretical point set. The overlapping points or nearest neighbor points are merged using a clustering and merging algorithm, and the theoretical points are associated with the three-dimensional positioning grid.

[0049] For each construction segment, perform graph theory connectivity testing and surface fit verification on the theoretical points; calculate the slope change rate based on the original theoretical point set, and determine whether to retain all theoretical points based on the preset change rate threshold.

[0050] A visual code is generated for each theoretical point to form a set of theoretical positioning points.

[0051] Specifically, the steps for outputting early warning information and correction positioning data include:

[0052] For each construction segment, the actual measured points on site were read according to the construction sequence, and the ICP local registration algorithm was used to...

[0053] A coarse match is performed between the field measurement points and the theoretical positioning point set, and each theoretical point obtains a corresponding field measurement point to form a matching pair;

[0054] For each matching pair, the chimney central axis is extracted from the three-dimensional solid model of the chimney outer casing, which serves as the theoretical benchmark.

[0055] Line coordinates are used to calculate radial deviation and elevation deviation;

[0056] When the radial deviation is greater than the preset first deviation threshold or the elevation deviation is greater than the preset second deviation threshold, an early warning is triggered and an early warning message is output, and the deviation point is recorded.

[0057] For deviation points, the radial correction component is calculated along the radial direction, and the elevation correction component is calculated along the vertical direction. The composite correction vector is obtained through vector synthesis, and associated with the corresponding theoretical point ID, template number, and construction segment number to generate correction timing data.

[0058] Specifically, the steps for outputting the as-built 3D solid model of the chimney outer casing and the full-cycle construction information database include:

[0059] After construction is completed, the completed chimney point cloud data is acquired. Statistical filtering algorithm and voxel grid downsampling are used to reduce point cloud noise and remove outliers to obtain the denoised completed chimney point cloud.

[0060] Using the 3D solid model of the outer casing of the chimney as a reference, coarse and fine registration are performed on the denoised chimney as-built point cloud, and the transformed chimney as-built point cloud is output.

[0061] After traversing the completed point cloud of the chimney and registering it with the corresponding points of the three-dimensional solid model surface of the chimney outer cylinder, the maximum distance between the completed point cloud of the chimney and the surface of the three-dimensional solid model of the chimney outer cylinder is calculated.

[0062] If the maximum distance is less than or equal to the preset maximum distance threshold, the registration is deemed successful; otherwise, the registration is deemed unsuccessful, and the process returns to the fine registration step for recalculation.

[0063] Specifically, the steps for outputting the as-built 3D solid model of the chimney outer casing and the full-cycle construction information database also include:

[0064] Horizontal slices were extracted from the registered chimney as-built point cloud, and the RANSAC algorithm was used to fit circles to extract the actual outer diameter and center coordinates.

[0065] The actual bottom outer diameter and actual decreasing coefficient are calculated by back-calculating the modified linear regression equation; the actual inner diameter is calculated by back-calculating the inner wall points of the registered chimney as-built point cloud; and the actual slope is calculated by modifying the actual slope formula.

[0066] Based on the outer diameter, inner diameter, and slope of the three-dimensional solid model of the chimney outer casing, calculate the outer diameter deviation, inner diameter deviation, and slope deviation;

[0067] Set various deviation thresholds. When any deviation exceeds the corresponding deviation threshold, the 3D solid model of the chimney outer casing will be corrected.

[0068] By employing RBF-based NURBS surface deformation, a displacement field is superimposed onto the control points of the NURBS surface to generate a corrected local surface patch. This patch is then seamlessly integrated with the uncorrected area and reassembled into a finished 3D solid model of the chimney outer cylinder, which is then output.

[0069] Integrate data from the entire construction process to build and output a full-cycle construction information database.

[0070] The beneficial effects of this invention are:

[0071] 1. This invention generates a 3D solid model and 3D positioning mesh for the outer casing of a chimney through BIM parametric modeling and elevation-driven continuous function relationships, reducing errors in manual modeling and dimensional calculations. Based on template deconstruction, layout optimization, and minimum loss algorithms, it quickly generates standard and non-standard template lists, reducing on-site layout and manual arrangement steps and improving template cutting and assembly efficiency. Combined with theoretical positioning point sets and real-time deviation monitoring, it improves the forming accuracy and construction safety of the chimney casing, solving the problems of low accuracy, poor efficiency, and difficult management in traditional chimney construction.

[0072] 2. This invention achieves real-time early warning and positioning correction of construction deviations based on three-dimensional laser measurement and ICP local registration algorithm, ensuring that the entire construction process is within a controllable range. In the completion stage, a three-dimensional solid model of the chimney outer shell is generated through point cloud fitting and NURBS surface correction, which completely preserves the data of the entire construction process and builds a full-cycle information database, realizing the traceability, verification and reusability of chimney construction. Digital technology is integrated into the entire chimney construction process, reducing manual intervention and rework, and improving construction quality and acceptance efficiency. Attached Figure Description

[0073] Figure 1 A schematic diagram of a construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology;

[0074] Figure 2 This is a flowchart illustrating the generation of a three-dimensional solid model of the outer casing of a chimney in this invention;

[0075] Figure 3 This is a flowchart illustrating the formation of the theoretical positioning point set in this invention;

[0076] Figure 4 This is a flowchart of the process for outputting early warning information and correction positioning data in this invention. Detailed Implementation

[0077] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0078] Example

[0079] refer to Figures 1 to 4 As shown in the figure, this embodiment introduces a construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology, including the following steps:

[0080] Key geometric and process parameters, including but not limited to slope, elevation, inner diameter, outer diameter, and segment height of 1.5m, are extracted from chimney construction-related documents. These parameters are then preprocessed to generate a BIM construction dataset containing design parameters, construction constraints, and segment division rules. The chimney construction-related documents include 2D chimney construction drawings, construction specifications, and on-site work condition records. Preprocessing includes data cleaning, format standardization, and consistency verification.

[0081] Based on the BIM construction dataset in the BIM platform, a continuous functional relationship between the outer diameter, inner diameter, and slope of the chimney outer cylinder is established with elevation as the driving variable. A three-dimensional solid model of the chimney outer cylinder is generated through parametric modeling. Construction segments are divided along the height of the chimney according to the construction requirement of 1.5m segment height. A 1.5m×1.5m three-dimensional positioning grid is generated for each construction segment. The model accuracy is verified, the dimensions are checked and the collision is checked to ensure that the three-dimensional solid model of the chimney outer cylinder is consistent with the design, the transition between each construction segment is smooth and there is no interference or conflict. Finally, the three-dimensional solid model of the chimney outer cylinder and the three-dimensional positioning grid are output as the theoretical benchmark.

[0082] Based on the current construction progress and corresponding stage elevation, the segment to be constructed is located in real time. Key dimensions of the corresponding construction segment, including outer diameter, inner diameter, and slope, are extracted from the 3D solid model of the chimney outer cylinder. The segment perimeter and taper gradient are calculated. A pre-set template specification library is called, and the surface of the corresponding construction segment is deconstructed and unfolded into a fan-shaped ring using a minimum loss algorithm. The fan-shaped ring is matched with the standard templates in the template specification library. Non-standard filling templates are generated for areas that cannot be covered after matching. The templates are arranged and virtually spliced ​​according to the splicing rules, generating a parameter list containing template number, cutting size, and splicing order. At the same time, the theoretical spatial coordinates of template corner points and screw hole positions are extracted from the 3D positioning grid to form a theoretical positioning point set, providing a reliable basis for on-site construction positioning and replacing manual calculation to avoid human error. Among these, the splicing rules are to minimize splices and losses.

[0083] During construction, 3D laser positioning equipment is used to acquire on-site measured points at the construction site of the chimney outer casing. These points are then compared point-by-point with the theoretical positioning point set to calculate radial and elevation deviations. When the radial deviation exceeds a preset first deviation threshold or the elevation deviation exceeds a preset second deviation threshold, warning information and correction positioning data are output. After construction, 3D laser scanning is used to acquire the chimney's completed point cloud data. After noise reduction and registration, this data is iteratively fitted with the 3D solid model of the chimney outer casing. Actual geometric parameters are calculated, and the 3D solid model of the chimney outer casing is locally corrected to ensure consistency with the actual structure. Finally, deviation records, correction information, acceptance data, and completion parameters are archived, and the completed 3D solid model of the chimney outer casing and a full-cycle construction information database are output, enabling digital traceability of the construction process and improving construction accuracy and safety.

[0084] Specifically, the steps for outputting the three-dimensional solid model and three-dimensional positioning mesh of the chimney outer casing as the theoretical benchmark include:

[0085] The data parsing module of the BIM platform is used to extract and verify the structure of the BIM construction dataset, removing outliers and standardizing parameter units, such as elevation in meters (m) and slope in degrees (°), to ensure data integrity and consistency. Using elevation as the driving variable, a continuous functional relationship is established between the chimney's outer diameter, inner diameter, slope, and elevation. The expression for this continuous functional relationship is shown below:

[0086] ;

[0087] ;

[0088] ;

[0089] in, The elevation is defined as the range from the bottom elevation of the chimney to the top elevation, which is consistent with the chimney design elevation range in the BIM construction dataset. For elevation The outer diameter of the chimney casing; For elevation The inner diameter of the outer casing of the chimney; For elevation The slope of the outer casing of the chimney; Design the outer diameter of the bottom of the chimney; Design the inner diameter of the bottom of the chimney; The linear decreasing coefficient of the chimney's inner and outer diameters is determined by the slope requirements in the BIM construction dataset to ensure compliance with design standards. For elevation The formula for calculating the design outer diameter of the chimney outer casing is used to calculate the outer diameter of the outer casing at different elevation positions; For elevation The formula for calculating the inner diameter of the outer casing of a chimney is used to calculate the inner diameter of the casing at different elevation positions. For elevation The slope calculation formula for the outer casing of the chimney is to convert the actual slope at the corresponding elevation by the ratio of the difference between the inner and outer diameters to the elevation, so as to ensure that the slope meets the design requirements.

[0090] Based on continuous function relationships, a three-dimensional solid model of the chimney outer casing is generated through the parametric modeling algorithm built into the BIM platform. The three-dimensional solid model of the chimney outer casing includes an input layer, a feature extraction layer, a parameter optimization layer, and an output layer. Each layer is embedded in the parametric modeling algorithm to realize the transformation from data to model.

[0091] The input layer receives the BIM construction dataset and continuous function relationship parameters verified by the data parsing module, including but not limited to the design outer diameter of the chimney bottom. Chimney bottom design inner diameter Linear decrease coefficient of chimney inner and outer diameter This provides basic data support for generating a three-dimensional solid model of the chimney outer casing;

[0092] The feature extraction layer is used to extract key features of the chimney outer casing from the verified BIM construction dataset and continuous function relationship, including but not limited to the correlation features between elevation and size, and slope change features. The extracted key features of the chimney outer casing are coupled with the continuous function relationship to filter out the core parameters required for the generation of the three-dimensional solid model of the chimney outer casing, such as the elevation value range.

[0093] The parameter optimization layer is used to combine construction specification parameters to optimize the linear decrease coefficient of the chimney's inner and outer diameters in a continuous functional relationship. Inner and outer diameter parameters , Dynamic optimization is performed, and the parameter value range is constrained to avoid dimensional deviations or slope anomalies. Dynamic optimization includes: targeting the dimensional accuracy and slope tolerance required by construction specifications, and iteratively adjusting the parameters using a gradient descent algorithm based on the core parameters output from the feature extraction layer. , , The parameters, determined according to the chimney construction specifications, are that the absolute deviation of the model dimensions from the design values ​​is less than or equal to 5mm, and the absolute deviation of the slope from the design values ​​is less than or equal to 0.5°. After each iteration, the parameter verification module built into the BIM platform calculates the model dimensions at each elevation position corresponding to the current parameters in real time. , ),slope The deviation from the centralized design value in the BIM construction data is compared with the dimensional limit to determine whether the deviation meets the standard, until the deviation is less than the dimensional limit; the range of constraint parameter values ​​includes: limited , The value range is less than or equal to the allowable deviation specified in the design documents, while also constraining arbitrary elevations. corresponding , All are greater than 0, and the outer cylinder wall thickness is... The wall thickness must be greater than or equal to the minimum design wall thickness to ensure structural safety; [The following appears to be a separate, unrelated sentence:] Limited The gradient of values ​​ensures the slope. The chimney taper changes continuously and monotonically along the height direction, without abrupt changes or reversals, ensuring a smooth transition in the chimney's tapering. The minimum design wall thickness is determined by the minimum thickness limit for the chimney wall specified in the construction specifications.

[0094] The output layer is used to output the initial 3D solid model of the chimney outer casing that meets the design requirements, and simultaneously outputs the parameter records during the generation process of the initial 3D solid model of the chimney outer casing, including the corresponding elevations. , , Numerical value;

[0095] Using design parameters from the BIM construction dataset as core training samples and historical chimney construction model data as auxiliary samples, a model training dataset is constructed. The sum of squared deviations between model dimensions and design values ​​is used as the loss function, and the 3D solid model of the chimney outer casing is iteratively trained using an Adam optimizer with a learning rate of 0.001 and a weight decay coefficient of 0.0001 for 200 iterations. During training, the parameter verification logic of the parameter optimization layer is invoked in each iteration to monitor model parameter deviations in real time, ensuring that the training process does not exceed the limits specified in the construction specifications. After training, the verified BIM construction dataset and elevation parameters are input in real time. Through function calculation and feature matching built into the 3D solid model of the chimney outer casing, the initial 3D solid model of the chimney outer casing and the corresponding function relationship parameter package are output.

[0096] Based on the initial 3D solid model of the chimney outer casing, the corresponding function relationship parameter package, and the construction segment division requirements, the construction segment division requirement is that the segment height is 1.5m, and the division range starts from the bottom elevation of the chimney and proceeds sequentially along the height direction to the top elevation. Using the segment division module of the BIM platform, the construction segments are divided along the height direction of the chimney according to the 1.5m standard. The mesh generation algorithm built into the BIM platform generates an initial 3D positioning mesh of 1.5m×1.5m for each construction segment. The mesh nodes are based on the bottom elevation of each construction segment and are associated with the elevation coordinates, inner and outer diameter parameters, and slope parameters of the corresponding segment. The output is a 3D model of the chimney outer casing with construction segment division and the initial 3D positioning mesh of each segment.

[0097] The model accuracy verification module of the BIM platform compares the key dimensions of the 3D model of the chimney outer cylinder with the construction segment division with the design parameter dimensions in the BIM construction dataset. The difference between the key dimensions and the design parameter dimensions is calculated to obtain the dimension deviation. For parts with dimension deviation greater than the dimension limit, the dynamic optimization logic of the parameter optimization layer is called to correct the parameters of the 3D model of the chimney outer cylinder with the construction segment division based on the continuous function relationship, and the corrected 3D positioning mesh is obtained.

[0098] Perform collision checks to identify interference conflicts between construction segments and between the positioning grid and the model surface. Based on the segment division requirements and continuous function relationships, adjust the node coordinates of the 3D positioning grid to eliminate interference conflicts. The adjustment process includes: marking interfering nodes on the BIM platform and extracting their coordinates and corresponding elevations; then calculating the theoretical coordinate range of the corresponding elevations using the corrected parameters; if the node coordinates overlap with the model surface, it is considered surface interference, and the Z-axis of the adjustment point along the normal is finely adjusted to be less than or equal to 2mm; if adjacent segments...

[0099] If node coordinates intersect, it is determined that the nodes intersect. Fine-tune the X and Y axes to keep the spacing between them at 0.1-0.2m. After adjustment, check again to confirm that there are no conflicts and that the requirements are met.

[0100] The data fusion module of the BIM platform integrates the corrected 3D model of the chimney outer casing, the 3D positioning grid, and all parameter records, eliminating redundant data, verifying data consistency, and finally outputting the final result.

[0101] The three-dimensional solid model and three-dimensional positioning mesh of the chimney outer casing, serving as the theoretical benchmark, are simultaneously output as complete parameter reports.

[0102] This report provides a basis for subsequent construction positioning.

[0103] Specifically, the steps for forming the theoretical location point set include:

[0104] For each construction segment, the bottom elevation of the current construction segment is used as the reference. and top elevation Using the boundary as the boundary, the outer cylinder surface patch of the current construction segment is extracted from the three-dimensional solid model of the chimney outer cylinder, which serves as the theoretical benchmark. Utilizing the parametric representation of the three-dimensional solid model of the chimney outer cylinder, the outer cylinder surface patch is parameterized as... Domain, in which The direction is circumferential, and the range of values ​​is... ; The direction is the height direction, and the value range is... ;

[0105] Read the coordinates of all grid nodes corresponding to the bottom elevation of the current construction segment from the three-dimensional positioning grid, and take the circumferential midline of all grid node coordinates as the reference direction for the unfolding of the sector ring, so as to ensure that the sector plane after the sector ring is unfolded is aligned with the on-site layout coordinate system.

[0106] The bottom outer diameter of the current construction segment is calculated using a continuous function expression. Top outer diameter Based on the bottom outer diameter and top outer diameter of the current construction segment, through Obtain the average radius Further calculation of the upper arc length of the sector ring. Lower arc length and radial height The calculation formula is as follows:

[0107] ;

[0108] ;

[0109] ;

[0110] in, This is the circumference of the outer circle at the top of the current construction segment; 1.5 is the circumference of the bottom outer circle of the current construction segment; 1.5 is the segment height. This is the cosine value of the slope of the outer cylinder surface of the current construction segment;

[0111] Calculate the upper arc length Lower arc length The average value is used to obtain the segment perimeter of the current construction segment; based on the bottom outer diameter of the current construction segment... Top outer diameter With segment height, through

[0112] Calculate the taper gradient of the current construction segment. This indicates the reduction in outer diameter per meter of height;

[0113] Using a fan-shaped ring as the raw material area to be cut, a two-dimensional matrix layout algorithm is used for template arrangement. The specific template arrangement process includes: abstracting each template in the template specification library as a rectangle, with the width being the arc length dimension and the height being the radial dimension, and recording the bendability adaptability coefficient. Based on the template material characteristics, thickness, and on-site bending construction process, the bendability adaptability coefficient is determined to be between 0 and 1. The objective function is to minimize the loss rate, while simultaneously constraining the number of joints. Each construction segment has no more than 3 circumferential joints, and vertical joints are continuous with a staggered distance greater than or equal to a staggered distance threshold. The staggered distance is the circumferential spacing between vertical joints of adjacent construction segments, and the staggered distance threshold is determined to be 300mm based on template splicing construction specifications and on-site construction error control requirements. A multi-objective particle swarm optimization iterative search is used to find the optimal combination, outputting a list of standard templates required to cover the fan-shaped ring and a list of standard templates in... The location coordinates within the domain; where the template specification library is determined by engineering design drawings, on-site construction equipment load-bearing capacity, and industry template standards and specifications; For the remaining areas not covered by standard templates, the non-standard template generation module is called to generate the geometric outline of the non-standard template based on the boundary shape of the remaining area, and the cutting dimensions of the non-standard template are calculated using the calculation formulas for the upper arc length, lower arc length, and radial height;

[0114] Standard templates and non-standard templates are classified according to The coordinates are inversely mapped back to a 3D curved surface for virtual splicing. Finite element meshes are used for alignment checks, verifying that the maximum gap between adjacent template boundaries is less than the gap threshold and the misalignment is less than the misalignment threshold. If the maximum gap between adjacent template boundaries is greater than the gap threshold or the misalignment is greater than the misalignment threshold, the alignment check fails. The template positions are rotated or swapped, and the process is repeated until the splicing rules are met, minimizing splices and losses. The gap threshold is set at 1mm according to the template splicing construction quality acceptance standards, and the misalignment threshold is set at 0.5mm according to the template installation flatness requirements. After splicing, a list of standard templates, non-standard template cutting dimensions, and the coordinates of each template position are compiled to generate a parameter list.

[0115] For each template in The four corner points in the domain are marked as ,in, , Given the total number of corner points of all formwork in the current construction segment, the three-dimensional function relationship of the chimney outer cylinder solid model is used to... Convert to three-dimensional space coordinates For surfaces that cannot be directly expressed analytically, bilinear interpolation is used. The domain mesh nodes are used to calculate the three-dimensional spatial coordinates. If the outer surface of the chimney is a regular surface that can be analytically expressed, such as a hyperboloid or a conical surface, the parameterized surface equation of the outer surface is a three-dimensional functional relationship, as shown below:

[0116]

[0117]

[0118]

[0119] in, for In the domain The outer cylinder radius corresponding to the direction For circumferential parameters, This refers to the height direction parameter; Circular parameters The corresponding cosine value is used to calculate the projection component of the corner point in the X-axis direction in three-dimensional space, which represents the circumferential horizontal position of the corner point relative to the central axis of the chimney. Circular parameters The corresponding sine value is used to calculate the projection component of the corner point along the Y-axis in three-dimensional space, and... Together, determine the specific circumferential location of the corner point on the horizontal plane. The elevation of the corner point relative to the bottom of the current construction segment along the Z-axis in three-dimensional space. The height increment, This is the bottom elevation of the current construction segment;

[0120] Using a 3D positioning mesh as a spatial reference frame, traverse all mesh nodes in the 3D positioning mesh, according to Calculate three-dimensional spatial coordinates Euclidean distance to each grid node ,in, The coordinates of the grid nodes are set. The distance limit is set to 5mm according to the on-site positioning accuracy requirements. If there are grid nodes whose Euclidean distance is less than or equal to the distance limit, the node attributes are directly inherited, including the elevation, number and normal vector of the grid nodes whose Euclidean distance is less than or equal to the distance limit. Otherwise, the theoretical coordinates of the corner point are calculated from the four surrounding grid nodes through bilinear interpolation, and the corner point is marked as a densified positioning point. The grid node ID from which the densified positioning point interpolation comes is recorded.

[0121] Based on the predefined screw hole layout in the template specification library, one hole is placed every 300mm along the perimeter of the template, with the center of the hole 50mm from the edge of the plate and a diameter of 16mm; in each template... Calculate the parametric coordinates of all holes in the domain. ,in, , The total number of screw holes in a single template is calculated using [template arc length / 300]×2 + [template radial height / 300]×2. An equidistant geodesic mapping method is used to map the hole positions from the planar template to the three-dimensional curved surface. Specifically, in the fan-shaped unfolded plane of the template, the hole positions are represented by planar coordinates. The planar distance is converted to the surface arc length along equidistant geodesics on the three-dimensional curved surface, and then the hole position coordinates are calculated. Ensure that the position of the hole on the three-dimensional curved surface is consistent with the layout of the planar template;

[0122] Using the surface normal vector provided by the three-dimensional solid model of the chimney outer cylinder, each hole position is expanded outward by a template thickness along the normal direction to obtain the spatial coordinates of the actual screw perforation point; the template thickness is determined to be 12mm according to the construction load requirements; due to the existence of construction errors, historical data is obtained from the historical construction database, and the hole position coordinates are increased by ±2mm of normal distribution noise as the theoretical allowable deviation range, which meets the on-site construction accuracy requirements;

[0123] The corner point set is obtained based on the 3D coordinate transformation result of the template corner points, and the screw hole set is obtained based on the 3D coordinate mapping result of the screw hole positions. The corner point set and screw hole set of each template are merged to form the original theoretical point set of the current construction segment. For the overlapping points or neighboring points in the original theoretical point set due to the splicing of plates, the corner points coincide or the hole spacing is too close, a clustering and merging algorithm is adopted. Using the Euclidean distance between points as a metric, points with an Euclidean distance of less than 1mm are grouped into one class, and the geometric center is taken as the unique theoretical point. The template shared by the unique theoretical point is recorded. The theoretical points in the original theoretical point set are associated with the 3D positioning grid. Each theoretical point is associated with at least one network node ID to form a traceable point-grid mapping relationship, which facilitates the quick search of the reference grid during on-site positioning.

[0124] For each construction segment, a graph connectivity test is performed on the theoretical points. An undirected graph is constructed with the theoretical points as nodes and the template edges or bolt hole connections as edges. The existence of isolated points in the undirected graph is checked. Isolated points are nodes that are not connected to any other nodes. If isolated points exist, their coordinates are recalculated.

[0125] For each construction segment, the surface fit of the theoretical points is checked, assuming the equation of the chimney outer surface is an implicit function. ,pass Calculate the absolute minimum distance from each theoretical point to the surface of the 3D solid model of the chimney's outer casing, where, , , The partial derivative of the equation of the outer surface of the chimney is given. According to the positioning accuracy requirements of the outer surface of the chimney, the judgment threshold is set to 2mm. If the absolute minimum distance is greater than the judgment threshold, the theoretical point is judged as a floating point. The floating point is corrected to the surface of the three-dimensional solid model of the outer surface of the chimney by projecting along the normal direction of the outer surface of the chimney, and the correction amount is recorded, that is, the coordinate difference before and after the correction.

[0126] To facilitate on-site layout, the original theoretical point set is adaptively sparsified by means of... Calculate the rate of change of slope ,in, The angle between the outer cylinder generatrix and the vertical direction. This is the rate of change of the angle between the outer cylinder generatrix and the vertical direction along the height direction, i.e., the rate of change of slope. Based on the balance between on-site layout efficiency and positioning accuracy, a change rate threshold of 0.5° / m is set. If the slope change rate is greater than the threshold, it is identified as a region of abrupt slope change, and all theoretical points are retained. If the slope change rate is less than or equal to the threshold, it is identified as a region of gentle curvature, and redundant theoretical points are eliminated by taking one point every 5° in the circumferential direction and one point every 0.5m in the vertical direction to reduce the amount of data. A visual code is generated for each theoretical point to form a set of theoretical positioning points. The visual code includes converting the three-dimensional coordinates into polar coordinates relative to the central axis of the chimney. Add a QR code string containing the theoretical point ID, template number, borehole number, and grid node ID; among which, The distance from the theoretical point to the central axis. For circumferential angle, Elevation.

[0127] Specifically, the steps for outputting the as-built 3D solid model of the chimney outer casing and the full-cycle construction information database include:

[0128] For each construction segment, the on-site measured points of the chimney outer casing construction area, collected by the 3D laser positioning equipment, are read according to the construction sequence. The ICP local registration algorithm is used to coarsely match the on-site measured points with the theoretical positioning point set. The coarse matching process includes: using the theoretical positioning point set as a reference, searching for the nearest theoretical point for each on-site measured point to establish a one-to-one correspondence; after completing the coarse matching, each theoretical point... Obtain the corresponding field measurement points This forms a matching pair;

[0129] For each matching pair, the chimney central axis is extracted from the three-dimensional solid model of the chimney outer casing, which serves as the theoretical benchmark.

[0130] Linear coordinates, calculating radial deviation based on the coordinates of the chimney's central axis. Deviation from elevation The formula for calculating radial deviation is: The formula for calculating elevation deviation is: Based on the construction precision requirements of the chimney outer casing and industry standards, a first deviation threshold of 5mm is set, and a second deviation threshold of 3mm is set according to the chimney elevation control standards and construction quality acceptance specifications. When the radial deviation exceeds the first deviation threshold or the elevation deviation exceeds the second deviation threshold, an early warning is triggered and an early warning message is output, and the corresponding theoretical point and the actual measured point are recorded as deviation points. For deviation points, the radial correction component is obtained by calculating the difference in radial distance between the actual measured point and the theoretical point from the actual measured point to the theoretical point. The elevation correction component is obtained by calculating the difference in elevation between the actual measured point and the theoretical point from the actual measured point in the vertical direction. The composite correction vector is obtained through vector synthesis. The synthesized correction vector is associated with the corresponding theoretical point ID, template number, and construction segment number to generate correction timing data;

[0131] After construction, 3D laser scanning was used to acquire as-built point cloud data of the chimneys. Statistical filtering algorithms and voxel mesh downsampling were employed for point cloud denoising and outlier removal to obtain the denoised as-built point cloud of the chimneys. The specific process included: for each chimney as-built point cloud data point, calculating the average distance from each point to all points in its neighborhood within a 0.1m radius; if the average distance of a single chimney as-built point cloud data point within the neighborhood exceeded twice the standard deviation of the global average distance, it was marked as an outlier and removed; and setting the point cloud density according to the requirements.

[0132] The voxel size is 5mm, and the centroid of the point cloud within the voxel is used as the representative point to reduce the amount of data while maintaining geometric features.

[0133] Using the 3D solid model of the chimney's outer casing as a reference, coarse and fine registration are performed on the denoised chimney as-built point cloud. The coarse registration process includes: extracting key points using the fast point feature histogram of the denoised chimney's as-built point cloud; and estimating the initial transformation matrix through rotation and translation using a sample consistency initial registration algorithm to initially align the denoised chimney's as-built point cloud with the 3D solid model of the chimney's outer casing. The fine registration process includes: using the ICP algorithm with normal constraints to iteratively optimize the initial transformation matrix; in each iteration, each element in the denoised chimney's as-built point cloud is compared with the initial transformation matrix. The algorithm searches for the nearest point on the surface of the 3D solid model of the chimney's outer casing, aiming to minimize the sum of the squared distances from each point to the surface of the 3D solid model of the chimney's outer casing. The initial transformation matrix is ​​updated, and the iteration stops after 200 iterations. Specifically, the algorithm calculates the minimum distance between each point in the denoised chimney as-built point cloud and each point on the surface of the 3D solid model of the chimney's outer casing using the shortest distance algorithm from point to surface. The minimum distance threshold is set to 10mm according to the registration accuracy requirements and the fitting standard between the point cloud and the model. If the minimum distance is less than or equal to the minimum distance threshold, it is judged as the nearest point.

[0134] After coarse and fine registration are completed, the transformed chimney as-built point cloud is output. The coordinate system of the chimney as-built point cloud is consistent with that of the 3D solid model of the chimney outer cylinder. After traversing the chimney as-built point cloud and registering it with the corresponding points on the surface of the 3D solid model of the chimney outer cylinder, the maximum distance between the chimney as-built point cloud and the surface of the 3D solid model of the chimney outer cylinder is calculated. According to the chimney as-built point cloud registration quality acceptance standard, the maximum distance threshold is set to 20mm. If the maximum distance is less than or equal to the maximum distance threshold, the registration is deemed qualified; if the maximum distance is greater than the maximum distance threshold, the registration is deemed unqualified, and the process returns to the fine registration step to recalculate.

[0135] From the registered chimney as-built point cloud, horizontal slices are taken at 0.5m intervals along the height direction, with each slice being 0.1m thick. For each slice, a circle is fitted using the RANSAC algorithm to extract the actual outer diameter. and the coordinates of the center of the circle; based on the modified linear regression equation The actual bottom outer diameter was calculated by least squares fitting. and actual decrease factor Similarly, using the inner wall points of the registered chimney as-built point cloud, the actual inner diameter is calculated by normal filtering and separation. By correcting the actual slope formula The actual slope was calculated. ;

[0136] Compare the actual outer diameter calculated in reverse Actual inner diameter Actual slope Outer diameter of the chimney outer shell 3D solid model , inner diameter With slope ,pass , , The outer diameter deviation, inner diameter deviation, and slope deviation were calculated.

[0137] According to the construction allowable deviation specification for the outer diameter of the chimney outer cylinder, the outer diameter deviation threshold is set to 3mm. According to the construction allowable deviation specification for the inner diameter of the chimney outer cylinder and the wall thickness control requirements, the inner diameter deviation threshold is set to 3mm. According to the construction allowable deviation specification for the slope of the chimney outer cylinder and the structural stability requirements, the slope deviation is set to ±0.1°. When the outer diameter deviation is greater than the outer diameter deviation threshold, or the inner diameter deviation is greater than the inner diameter deviation threshold, or the slope deviation is greater than the slope deviation threshold, the chimney outer cylinder three-dimensional solid model correction is triggered.

[0138] The correction is performed using RBF-based NURBS surface deformation. The correction process includes: selecting out-of-limit regions where the outer diameter deviation exceeds the outer diameter deviation threshold, the inner diameter deviation exceeds the inner diameter deviation threshold, or the slope deviation exceeds the slope deviation threshold; uniformly sampling control points every 0.2m within these out-of-limit regions; and using the signed distance from the registered chimney as-built point cloud to the surface of the chimney's outer 3D solid model as the displacement field constraint to construct the RBF interpolation function. ,in, , This represents the total number of control points sampled within the area exceeding the limit. The interpolation coefficients are obtained by solving the linear equation. get, Control points The corresponding signed distance displacement; For thin plate spline kernel functions, Points to be corrected To the control point The Euclidean distance;

[0139] The displacement field is superimposed onto the control points of the NURBS surface to generate a corrected local surface patch.

[0140] The non-overlapping region stitching smoothing algorithm seamlessly integrates the corrected local surface patches with the uncorrected areas, ensuring overall continuity and yielding corrected local NURBS surfaces. These corrected local NURBS surfaces are then reconstructed into a complete as-built 3D solid model of the chimney outer casing. By integrating data from the entire construction process, including but not limited to deviation records, correction and positioning data, registration parameters, actual geometric parameters, model correction logs, template layout lists, and acceptance records, a structured data association is built using a PostgreSQL database. Combined with a graph database to store the traceability relationships between entities, a full-cycle construction information database is obtained. Finally, the as-built 3D solid model of the chimney outer casing and the full-cycle construction information data are output.

[0141] In summary, this invention achieves digital management and control of chimney construction through BIM technology, solving the problems of large calculation errors, inaccurate positioning, and difficulty in traceability in traditional construction, thereby improving construction accuracy and safety. First, key geometric and process parameters from the chimney's two-dimensional drawings, construction specifications, and on-site conditions are extracted and preprocessed to generate a BIM construction dataset. In the BIM platform, a continuous functional relationship between the outer diameter, inner diameter, and slope of the outer cylinder is established, driven by elevation. A three-dimensional solid model of the chimney's outer cylinder is generated through parametric modeling. The construction is divided into segments at 1.5m heights, and a three-dimensional positioning mesh is generated. After accuracy verification and collision checks, the three-dimensional solid model of the chimney's outer cylinder and the three-dimensional positioning mesh are output as theoretical benchmarks. Secondly, based on the construction progress, the sections to be constructed are located, dimensional parameters are extracted, and the template specification library is called. A minimum loss algorithm is used to deconstruct the curved surface into fan-shaped rings, matching standard templates and generating non-standard templates. Virtual splicing is completed, and a template parameter list is generated. Simultaneously, the theoretical coordinates of template corner points and screw hole positions are extracted. After coordinate transformation, interpolation correction, and sparsification, a theoretical positioning point set is formed, providing a basis for on-site construction. During construction, 3D laser positioning equipment is used to acquire on-site measured points. The ICP algorithm is used to match these points with the theoretical positioning point set, calculating radial and elevation deviations. If deviations exceed limits, early warning information and correction positioning data are output. After construction, 3D laser scanning is used to acquire the chimney's completed point cloud. After noise reduction, coarse registration, and fine registration, iterative fitting is performed with the 3D solid model of the chimney's outer cylinder. Actual geometric parameters are calculated inversely. For areas exceeding limits, NURBS surface deformation correction using RBF is applied, generating the completed 3D solid model of the chimney's outer cylinder. Finally, the data from the entire construction process is integrated, a structured association is built using a PostgreSQL database, and data traceability is achieved by combining a graph database. The final output is a completed 3D solid model and a full-cycle construction information database, realizing digital traceability of the entire construction process, improving the accuracy and safety of chimney outer casing construction, and reducing human error and construction rework.

[0142] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology, characterized in that, include: Key geometric and process parameters are extracted from chimney construction-related documents and preprocessed to generate a BIM construction dataset. Using elevation as the driving variable, a continuous functional relationship between the outer diameter, inner diameter, and slope of the chimney outer cylinder is established. A three-dimensional solid model of the chimney outer cylinder is generated through parametric modeling. Construction segments are divided and a three-dimensional positioning mesh is generated. After verification, the three-dimensional solid model of the chimney outer cylinder and the three-dimensional positioning mesh are output as theoretical benchmarks. The system locates the construction segment in real time, extracts the key dimensions of the corresponding construction segment from the 3D solid model of the chimney outer cylinder, calculates the segment perimeter and taper gradient, deconstructs the surface of the corresponding construction segment and matches it with the preset template specification library to generate a parameter list, and extracts the theoretical spatial coordinates of template corner points and screw hole positions from the 3D positioning mesh to form a theoretical positioning point set. During construction, the radial and elevation deviations are calculated by combining on-site measured points with theoretical positioning point sets. When deviations exceed the limits, early warning information and correction positioning data are output. After completion, the chimney as-built point cloud data is acquired for iterative fitting and local correction, and the construction information is archived. The as-built chimney outer cylinder three-dimensional solid model and the full-cycle construction information database are output.

2. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 1, characterized in that, The specific steps for generating a 3D solid model of the chimney outer casing include: The data parsing module of the BIM platform is used to extract and verify the structured BIM construction dataset. Using elevation as the driving variable, a continuous functional relationship between the outer diameter, inner diameter, slope, and elevation of the chimney outer casing is established. Based on continuous function relationships, the parametric modeling algorithm built into the BIM platform generates a three-dimensional solid model of the chimney outer cylinder, including an input layer, a feature extraction layer, a parameter optimization layer, and an output layer. The input layer is used to receive the BIM construction dataset and continuous function relationship parameters after being verified by the data parsing module; The feature extraction layer is used to extract key features of the chimney outer casing from the verified BIM construction dataset and continuous function relationships, and couple them with the continuous function relationships to filter out the core parameters required for generating the three-dimensional solid model of the chimney outer casing.

3. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 2, characterized in that, The specific steps for generating a 3D solid model of the chimney outer casing also include: The parameter optimization layer is used to combine construction specification parameters to optimize the linear relationship between the inner and outer diameters of the chimney in a continuous functional relationship. The decreasing coefficient and inner and outer diameter parameters are dynamically optimized, and the range of parameter values ​​is constrained. The output layer is used to output the initial 3D solid model and parameter records of the outer casing of the chimney. Using the design parameters in the BIM construction dataset as the core training samples and combining historical chimney construction model data as auxiliary samples, a model training dataset is constructed. The sum of squared deviations between the model dimensions and the design values ​​was used as the loss function, and the Adam optimizer was combined to iteratively train the 3D solid model of the chimney outer casing. During training, the parameter validation logic of the parameter optimization layer is invoked in each iteration to monitor the model parameter deviation in real time. After training, the validated BIM construction dataset and elevation parameters are input in real time. Through function calculation and feature matching, the initial three-dimensional solid model of the chimney outer cylinder and the corresponding function relationship parameter package are output.

4. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 3, characterized in that, The specific steps for outputting the three-dimensional solid model and three-dimensional positioning mesh of the chimney outer casing as a theoretical benchmark include: Based on the initial three-dimensional solid model of the outer casing of the chimney, the corresponding function relationship parameter package, and the requirements for dividing the construction segments, the construction segments are divided along the height of the chimney. Generate an initial three-dimensional positioning mesh for each construction segment, associate the elevation, inner and outer diameters and slope parameters of the corresponding segment, and output a three-dimensional model of the chimney outer cylinder with construction segment division and the initial three-dimensional positioning mesh. Calculate the dimensional deviation, call the dynamic optimization logic of the parameter optimization layer for the parts with excessive dimensional deviation, and correct the parameters of the chimney outer cylinder 3D model divided by construction segments based on the continuous function relationship to obtain the corrected 3D positioning mesh. Perform collision checks to identify interference conflicts, adjust the node coordinates of the 3D positioning mesh to eliminate interference conflicts, and verify and confirm the results again after adjustment; Integrate and correct the 3D model of the chimney outer casing, the 3D positioning mesh, and all parameter records, verify the data consistency, and output the 3D solid model of the chimney outer casing and the 3D positioning mesh as the theoretical benchmark.

5. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 4, characterized in that, The specific steps for calculating the segment perimeter and the convergence gradient include: For each construction segment, using the bottom and top elevations of the current construction segment as boundaries, the outer cylinder surface patch of the current construction segment is extracted from the three-dimensional solid model of the chimney outer cylinder, which serves as the theoretical benchmark, and parameterized. domain; Read the coordinates of all grid nodes corresponding to the bottom elevation of the current construction segment, and take the circumferential midline of all grid node coordinates as the reference direction for the expansion of the fan-shaped ring. The bottom outer diameter, top outer diameter, and average radius of the current construction segment are calculated using a continuous function relationship expression, and the upper arc length, lower arc length, and radial height of the fan-shaped ring are also calculated. The average value of the upper and lower arc lengths is used to obtain the perimeter of the current construction segment. The tapering gradient of the current construction segment is calculated based on the bottom outer diameter, top outer diameter, and segment height.

6. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 5, characterized in that, The specific steps for generating the parameter list include: Using a fan-shaped annular zone as the raw material area, a two-dimensional matrix nesting algorithm is used for template arrangement. Multi-objective particle swarm optimization iteratively searches for the optimal combination, outputting a list of standard templates required to cover the fan-shaped annular zone and... Position coordinates within the domain; For the remaining areas not covered by the standard template, generate the geometric contour of the non-standard template based on the boundary shape, and calculate the cutting dimensions of the non-standard template; The standard and non-standard templates are inversely mapped back to a 3D surface for virtual splicing and alignment detection. If the maximum gap between adjacent template boundaries is greater than the preset gap threshold or the misalignment is greater than the preset misalignment threshold, the alignment test is deemed to have failed. The template positions are rotated or swapped and the test is repeated until the seam rule is met. Summarize the list of standard templates, the cutting dimensions of non-standard templates, and the position coordinates of each template to generate a parameter list.

7. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 6, characterized in that, The specific steps for forming the theoretical location point set include: Place each template in The corner points in the domain are converted into three-dimensional spatial coordinates. For surfaces that cannot be analytically represented, bilinear interpolation is used to calculate the three-dimensional spatial coordinates. Traverse the 3D positioning grid and calculate the Euclidean distance using 3D spatial coordinates; If the Euclidean distance is less than or equal to the preset distance limit, the node attributes are directly inherited; otherwise, the theoretical coordinates of the corner points are calculated and marked as encrypted positioning points. Based on the relative layout of the screw holes, calculate the parameter coordinates of all hole positions and map them onto a three-dimensional surface. Expand along the surface normal vector to obtain the spatial coordinates of the actual screw piercing point. The corner point set and screw hole position set are obtained and combined into the original theoretical point set. The overlapping points or nearest neighbor points are merged using a clustering and merging algorithm, and the theoretical points are associated with the three-dimensional positioning grid. For each construction segment, perform graph theory connectivity testing and surface fit verification on the theoretical points; calculate the slope change rate based on the original theoretical point set, and determine whether to retain all theoretical points based on the preset change rate threshold. A visual code is generated for each theoretical point to form a set of theoretical positioning points.

8. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 7, characterized in that, The specific steps for outputting early warning information and correction positioning data include: For each construction segment, the on-site measured points are read according to the construction sequence. The ICP local registration algorithm is used to coarsely match the on-site measured points with the theoretical positioning point set. Each theoretical point obtains the corresponding on-site measured point to form a matching pair. For each matching pair, the chimney central axis is extracted from the three-dimensional solid model of the chimney outer casing, which serves as the theoretical benchmark. Line coordinates are used to calculate radial deviation and elevation deviation; When the radial deviation is greater than the preset first deviation threshold or the elevation deviation is greater than the preset second deviation threshold, an early warning is triggered and an early warning message is output, and the deviation point is recorded. For deviation points, the radial correction component is calculated along the radial direction, and the elevation correction component is calculated along the vertical direction. The composite correction vector is obtained through vector synthesis, and associated with the corresponding theoretical point ID, template number, and construction segment number to generate correction timing data.

9. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 8, characterized in that, The specific steps for outputting the as-built 3D solid model of the chimney outer casing and a full-cycle construction information database include: After construction is completed, the completed chimney point cloud data is acquired. Statistical filtering algorithm and voxel grid downsampling are used to reduce point cloud noise and remove outliers to obtain the denoised completed chimney point cloud. Using the 3D solid model of the outer casing of the chimney as a reference, coarse and fine registration are performed on the denoised chimney as-built point cloud, and the transformed chimney as-built point cloud is output. After traversing the completed point cloud of the chimney and registering it with the corresponding points of the three-dimensional solid model surface of the chimney outer cylinder, the maximum distance between the completed point cloud of the chimney and the surface of the three-dimensional solid model of the chimney outer cylinder is calculated. If the maximum distance is less than or equal to the preset maximum distance threshold, the registration is deemed successful; otherwise, the registration is deemed unsuccessful, and the process returns to the fine registration step for recalculation.

10. The construction method for chimney outer cylinder formwork deconstruction and real-time positioning based on BIM technology according to claim 9, characterized in that, The specific steps for outputting the as-built 3D solid model of the chimney outer casing and the full-cycle construction information database also include: Horizontal slices were extracted from the registered chimney as-built point cloud, and the RANSAC algorithm was used to fit circles to extract the actual outer diameter and center coordinates. The actual bottom outer diameter and actual decreasing coefficient are calculated by back-calculating the modified linear regression equation; the actual inner diameter is calculated by back-calculating the inner wall points of the registered chimney as-built point cloud; and the actual slope is calculated by modifying the actual slope formula. Based on the outer diameter, inner diameter, and slope of the three-dimensional solid model of the chimney outer casing, calculate the outer diameter deviation, inner diameter deviation, and slope deviation; Set various deviation thresholds. When any deviation exceeds the corresponding deviation threshold, the 3D solid model of the chimney outer casing will be corrected. By employing RBF-based NURBS surface deformation, a displacement field is superimposed onto the control points of the NURBS surface to generate a corrected local surface patch. This patch is then seamlessly integrated with the uncorrected area and reassembled into a finished 3D solid model of the chimney outer cylinder, which is then output. Integrate data from the entire construction process to build and output a full-cycle construction information database.

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