Large-span concrete-filled steel tube main arch data acquisition and analysis method, system and device

Abstract

The invention relates to the technical field of engineering data processing, in particular to a large-span concrete-filled steel tube main arch data collection and analysis method, system and device, and the method mainly comprises the steps: obtaining the point cloud data of the landform where a main arch is located, building a three-dimensional point cloud model through the point cloud data, and carrying out the calculation of the three-dimensional point cloud model. Based on the three-dimensional point cloud model, calculating to obtain a shadow region of the main arch in the acquisition time period, obtaining real-time meteorological data of the main arch at different time periods of a plurality of observation points, based on the real-time meteorological data and a Dilger model, obtaining a heat flux density of a surface unit of the main arch, and obtaining an initial temperature of the main arch; and the temperature stress of the section of the main arch is obtained and output through the temperature distribution and the initial temperature of the main arch. Through the above method, the collected data is further analyzed, feedback of the bridge temperature distribution result and the temperature stress result is realized, comprehensive understanding and evaluation of the temperature influence of the structure in actual operation are ensured, and detailed data support is provided for safety analysis of the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering data processing, and in particular to a method, system and device for collecting and analyzing data of a large-span steel tube concrete main arch. Background Art

[0002] With the rapid development of bridge construction in my country, the requirements for construction control of large-span steel tube concrete arch bridge structures during the construction phase and health monitoring during the operation phase are becoming increasingly complex, systematic and refined. In the process of bridge construction, construction control, as an important component, not only needs to determine the construction methods and process conditions based on structural analysis and on-site measurement results, but also needs to set appropriate construction parameters to ensure that the bridge remains safe and stable throughout the construction period. In the operation phase, health monitoring can reflect the health status of the bridge under the combined action of various loads in real time.

[0003] Meteorological data such as solar radiation, wind speed, and temperature are important factors that affect construction control parameters and operational health status. Only through real-time and accurate measurement of these meteorological parameters can the accuracy of structural health monitoring be ensured. However, after current data collection, more detailed analysis is often not carried out, and the judgment of structural safety needs to be improved.

[0004] In addition, the current measurement method is to set up meteorological stations near the bridge site or at different cross-sections of the bridge to obtain meteorological parameter data. However, these meteorological stations are fixed. For large-span steel tube concrete arch bridges, as the span and height increase, the meteorological parameters at different locations of the bridge may be different. With the increase in the number of fixed meteorological station locations, a series of problems will arise, such as high collection costs, difficulty in installation, and difficulty in data transmission. Summary of the invention

[0005] The purpose of the present invention is to provide a method, system and device for data collection and analysis of a large-span steel tube concrete main arch to solve the above-mentioned problems in the prior art.

[0006] The embodiments of the present invention are implemented by the following technical solutions:

[0007] In a first aspect, the present invention provides a method for data collection and analysis of a large-span steel tube concrete main arch, comprising:

[0008] Obtain point cloud data of the topography where the main arch is located, establish a three-dimensional point cloud model through the point cloud data, and calculate the shadow area of ​​the main arch during the acquisition period based on the three-dimensional point cloud model;

[0009] Based on the shadow area, the non-shadow area is obtained, the real-time meteorological data of the main arch at different time periods at several observation points are obtained, and the heat flux density of the surface unit of the main arch is obtained based on the real-time meteorological data and the Dilger model;

[0010] The temperature distribution on the main arch surface is obtained through the heat flux density, the initial temperature of the main arch is obtained, and the temperature stress of the main arch section is obtained and output through the temperature distribution and the initial temperature of the main arch.

[0011] Preferably, establishing a three-dimensional point cloud model through point cloud data includes:

[0012] Determine the scope of the target area and set the control points for collecting point cloud data, determine the layout parameters of the collection base station and set the flight route of the first UAV, and use the UAV to collect image data at the location of the collection base station;

[0013] Set the heading overlap rate and lateral overlap rate, and set the flight altitude limit function of the drone through the heading overlap rate;

[0014] The main arch is located at a location where three-dimensional modeling is performed on the spot to obtain a three-dimensional model of the main arch, the collected image data is obtained, and a three-dimensional point cloud model with real coordinate information is synthesized through the image point coordinates and control points in the overlapping area of ​​the image data.

[0015] Preferably, the function of setting the flight altitude limit of the drone includes:

[0016]

[0017] Where H is the flight altitude of the UAV, Δx is the terrain height difference, and O is the heading overlap rate.

[0018] Preferably, obtaining the shadow distribution area of ​​the main arch during the acquisition period includes:

[0019] Establishing a three-dimensional shell unit model of the main arch based on a finite element unit, and importing the three-dimensional model of the main arch into the three-dimensional shell unit model of the main arch;

[0020] Discretize the surface of the main arch three-dimensional shell unit model into surface units of triangular meshes, and establish unit sets and node coordinate sets of different components;

[0021] The solar altitude angle and azimuth at a certain moment are obtained, and the solar direction vector at that moment is obtained through the altitude angle and azimuth. The solar direction vector is used to determine whether any surface unit of the main arch is blocked by the terrain and landforms, and the shadow area of ​​the main arch is obtained.

[0022] Preferably, judging whether any surface unit of the main arch is blocked by the topography by the sun direction vector comprises:

[0023] Obtain the three unit node coordinates of the surface unit scattered into a triangular mesh, through the three unit node coordinates;

[0024] The center point coordinates are projected along the sun direction vector to determine whether a projection point is formed at any position of the main arch three-dimensional shell unit model. If a projection point is formed, the surface unit is determined to be a shadow area at this moment. If no projection point is formed, the surface unit is determined to be a non-shadow area at this moment.

[0025] Preferably, the determining that the surface unit is a shadow area at this moment includes determining that the surface unit is a self-shadow area blocked by its own back surface, or an other-shadow area blocked by other components, including:

[0026] Calculate the element normal vector of the surface element through the three element node coordinates;

[0027] Calculate whether the dot product of the sun direction vector and the element normal vector is less than or equal to 0. If it is less than or equal to 0, the surface element is divided into a self-shadow area. If it is greater than 0, the center point of the surface element is obtained through the element node coordinates.

[0028] A ray is established through the center point and the sun direction vector, the intersection of the ray and any plane is taken as the starting point, and three vectors are constructed with three unit nodes as the end points. After cross-producting the three vectors, it is determined whether the directions are the same. If they are the same, the surface unit is judged as the shadow area, if not, it is judged as the non-shadow area.

[0029] Preferably, the acquiring of real-time meteorological data of the main arch at different time periods includes setting a second UAV flight route, and the second UAV flight route includes:

[0030] Determine the arch rib type of the bridge, wherein the arch rib type includes a single arch rib and multiple arch ribs;

[0031] When the arch rib type is determined to be a single arch rib, a signal is sent to make the UAV fly along the outer side of the arch rib parallel to the arch rib axis;

[0032] When the rib type is determined to be multiple ribs, a signal is sent to cause the drone to fly in a zigzag pattern along the outer side of the rib parallel to the rib axis, alternating up and down.

[0033] Preferably, obtaining the heat flux density of the main arch surface unit includes:

[0034] The theoretical heat flux density is obtained through the Dilger model and the angle of the sun's rays;

[0035] Obtain the direct solar radiation value in the real-time meteorological data, define the error function, and find the adjustment coefficient that minimizes the error function E through the least squares method;

[0036] The theoretical heat flux density at each observation point is scaled according to the adjustment coefficient to obtain the corrected heat flux density.

[0037] In the second aspect, a data acquisition and analysis system for a large-span steel tube concrete main arch includes:

[0038] A three-dimensional model building module is configured to obtain point cloud data of the topography where the main arch is located, and to build a three-dimensional point cloud model through the point cloud data;

[0039] A shadow recognition module is configured to calculate the shadow area of ​​the main arch within the acquisition period based on the three-dimensional point cloud model;

[0040] The solar radiation model calculation module is configured to obtain the non-shadow area based on the shadow area, obtain the real-time meteorological data of the main arch at different time periods at several observation points, and obtain the heat flux density of the surface unit of the main arch based on the real-time meteorological data and the Dilger model;

[0041] The temperature field analysis module is configured to obtain the temperature distribution of the main arch surface through the heat flux density, obtain the initial temperature of the main arch, and obtain and output the temperature stress of the main arch section through the temperature distribution and the initial temperature of the main arch;

[0042] A main control device is connected to the three-dimensional model building module, the shadow recognition module, the solar radiation model calculation module and the temperature field analysis module, and is used to execute the above-mentioned large-span steel tube concrete main arch data collection and analysis method.

[0043] In a third aspect, a data collection and analysis device for a large-span steel tube concrete main arch includes a drone;

[0044] The UAV is provided with a meteorological data collection device and a processing unit, and the processing unit is connected to the meteorological data collection device and the UAV, and is used to execute the above-mentioned large-span steel tube concrete main arch data collection and analysis method;

[0045] The meteorological data collection device includes a wind speed meter, a wind direction meter, a solar radiation sensor, and a temperature sensor.

[0046] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0047] The method provided by the present invention mainly includes obtaining point cloud data of the topography where the main arch is located, establishing a three-dimensional point cloud model through the point cloud data, calculating the shadow area of ​​the main arch during the acquisition period based on the three-dimensional point cloud model, obtaining real-time meteorological data of the main arch at different periods at several observation points, and obtaining the heat flux density of the main arch surface unit based on the real-time meteorological data and the Dilger model; obtaining the temperature distribution of the main arch surface through the heat flux density, obtaining the initial temperature of the main arch, and obtaining and outputting the temperature stress of the main arch section through the temperature distribution and the initial temperature of the main arch. Through the above method, the collected data is further analyzed, and the feedback of the bridge temperature distribution results and temperature stress results is realized, ensuring a comprehensive understanding and evaluation of the temperature impact of the structure in actual operation, and providing detailed data support for the safety analysis of the structure.

[0048] Secondly, the present invention also uses drones as carriers to collect, transmit and analyze various data, so that data from multiple points of the main arch can be collected through a set of equipment, which reduces costs and solves the problem of difficult installation of current fixed meteorological stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 The structural temperature field calculation process of the present invention;

[0051] Figure 2 Schematic diagram of a point cloud data set of the present invention.

[0052] Figure 3 It is a schematic diagram of the imaging range of the present invention;

[0053] Figure 4 It is a schematic diagram of image overlap of the present invention;

[0054] Figure 5 It is a schematic diagram of the overlapping area of ​​the present invention;

[0055] Figure 6 It is a schematic diagram of projection points of the present invention;

[0056] Figure 7 A schematic diagram of a triangular mesh and three nodes of the present invention;

[0057] Figure 8 It is a schematic diagram of the judgment process of self-shadow and other-shadow of the present invention;

[0058] Fig. 9 A schematic diagram of the flight route of a single-arch UAV of the present invention;

[0059] Fig.10 A schematic diagram of the flight route of the multi-arch UAV of the present invention;

[0060] Fig.11 It is a structural schematic diagram of the data collection and analysis device of the present invention;

[0061] Icons: 1- wind speed meter, 2- wind direction meter, 3- solar radiation sensor, 4- temperature sensor, 5- drone, 6- camera. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0063] The division of modules in the application is a logical division. There may be other divisions in actual application. For example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed.

[0064] The modules or submodules described independently may be physically separated or not: they may be implemented by software or hardware, and some modules or submodules may be implemented by software, and the processor may call the software to implement the functions of these modules or submodules, and other modules or submodules may be implemented by hardware, such as by hardware circuits. In addition, some or all of the modules may be selected according to actual needs to achieve the purpose of the present application.

[0065] Please refer to Figure 1-2 As shown, the present invention provides a data collection and analysis method for a large-span steel tube concrete main arch, comprising:

[0066] S101: acquiring point cloud data of the topography where the main arch is located, establishing a three-dimensional point cloud model through the point cloud data, and calculating the shadow area of ​​the main arch during the acquisition period based on the three-dimensional point cloud model;

[0067] Using the high-definition camera carried by the drone, based on the altitude of the origin of the coordinate system, a grid was arranged within 500m outside the bridge outline in the bridge site plan to obtain a large number of coordinate point cloud data sets of the terrain and landforms near the bridge site, which were used to generate a three-dimensional model of the terrain and landforms.

[0068] S102: Based on the shadow area, a non-shadow area is obtained, real-time meteorological data of the main arch at different time periods at several observation points are obtained, and heat flux density of the surface unit of the main arch is obtained based on the real-time meteorological data and the Dilger model;

[0069] A take-off and landing platform for drones is set up near the arch foot of the arch bridge. The drone is equipped with a high-definition camera and a portable meteorological detector, and flies to a designated position directly above the centerline of the bridge span, which is not blocked by other parts of the bridge to ensure complete sunlight. It hovers at this position and collects meteorological data, including instantaneous horizontal plane direct irradiance, instantaneous horizontal plane scattered irradiance and temperature, and establishes the origin of the coordinate system at this position, and records the altitude of this point.

[0070] S103: obtaining the temperature distribution of the main arch surface through the heat flux density, acquiring the initial temperature of the main arch, and obtaining and outputting the temperature stress of the main arch cross section through the temperature distribution and the initial temperature of the main arch.

[0071] Specifically, the location and number of sections where the temperature field needs to be calculated are determined. Then, the unit sets and coordinate information contained in the sections at different locations are automatically identified from the three-dimensional model of the bridge. Using this information, a two-dimensional model is automatically generated, and a two-dimensional heat conduction differential equation is established with a constant material thermal conductivity and no internal heat source.

[0072]

[0073] Where t is temperature, τ is time, a is thermal diffusivity, and x, y, and z are spatial coordinates in a rectangular coordinate system.

[0074] Furthermore, the collected air temperature is applied to the edge of the two-dimensional model as the first-type boundary condition of the heat conduction problem.

[0075] Furthermore, the collected wind speed data of cross sections at different locations, combined with the convection heat transfer coefficient and the temperature of the surrounding fluid, are applied to the edge of the two-dimensional model as the third type of boundary conditions for the heat conduction problem.

[0076] Furthermore, the heat flux density of the surface unit is used as the second type of boundary condition for the heat conduction problem and applied to the units corresponding to the edges in the two-dimensional model.

[0077] In this way, the temperature distribution of the bridge cross section can be calculated, and combined with the initial temperature of the bridge when it is completed, the temperature stress of the bridge cross section can be calculated using finite element software.

[0078] The method provided by the present invention mainly includes obtaining point cloud data of the topography where the main arch is located, establishing a three-dimensional point cloud model through the point cloud data, calculating the shadow area of ​​the main arch during the acquisition period based on the three-dimensional point cloud model, obtaining real-time meteorological data of the main arch at different periods at several observation points, and obtaining the heat flux density of the main arch surface unit based on the real-time meteorological data and the Dilger model; obtaining the temperature distribution of the main arch surface through the heat flux density, obtaining the initial temperature of the main arch, and obtaining and outputting the temperature stress of the main arch section through the temperature distribution and the initial temperature of the main arch. Through the above method, the collected data is further analyzed, and the feedback of the bridge temperature distribution results and temperature stress results is realized, ensuring a comprehensive understanding and evaluation of the temperature impact of the structure in actual operation, and providing detailed data support for the safety analysis of the structure.

[0079] An exemplary embodiment of the present invention is as follows Figure 3-5 As shown, establishing a three-dimensional point cloud model through point cloud data includes:

[0080] S201: Determine the scope of the target area, set control points for collecting point cloud data, determine the layout parameters of the collection base station and set the flight route of the first unmanned aerial vehicle, and use the unmanned aerial vehicle to collect image data at the location of the collection base station;

[0081] Among them, the control point needs to specify its latitude, longitude, altitude and other information, and the acquisition base station layout parameters can include shooting distance, observation area length, base station spacing, etc. The resolution of the image data can be obtained through the above parameters and the parameters of the shooting camera.

[0082]

[0083] Where H is the shooting distance, p s is the pixel size, f is the focal length of the camera, and Y is the resolution.

[0084] After obtaining the resolution, the parameters can be adjusted according to the ground resolution requirements so that the resolution meets the detection requirements.

[0085] S202: Setting the heading overlap rate and the lateral overlap rate, and setting the flight altitude limit function of the UAV through the heading overlap rate;

[0086] When there is a height difference in the terrain, the overlapping shadow area will gradually become smaller. The key to point cloud modeling is to calculate the coordinates of each encrypted point in the image by measuring the point coordinates in the overlapping area of ​​the image, combining the coordinates of the control points and the collective relationship between the image and the photographed terrain. Therefore, the reduction of overlapping shadows will lead to a decrease in the accuracy of modeling. In order to meet the accuracy requirements of modeling, the heading overlap rate of this embodiment is set to 60%-80%, and the lateral overlap rate is set to 15%-80%.

[0087] Specifically, the flight altitude limit function of the drone is set as follows:

[0088]

[0089] Where H is the flight altitude of the UAV, Δx is the terrain height difference, and O is the heading overlap rate.

[0090] S203: Performing on-site three-dimensional modeling of the location of the main arch to obtain a three-dimensional model of the main arch, acquiring the collected image data, and synthesizing a three-dimensional point cloud model with real coordinate information through the coordinates of the image points and control points in the overlapping area of ​​the image data.

[0091] After obtaining relatively ideal image data, the image data is spliced ​​and integrated into a three-dimensional point cloud model with real coordinate information by using the image point coordinates of the overlapping area of ​​the image data, combined with the pre-set control point information, and using the focal length of the captured image, control point information, etc.

[0092] The established model is edited, mainly to eliminate or trim points irrelevant to modeling, and then the 3D model is smoothed and denoised, and finally a solid 3D point cloud model of the target area is obtained.

[0093] An exemplary embodiment of the present invention is as follows Figure 6-8 As shown, the shadow distribution area of ​​the main arch during the acquisition period includes:

[0094] S301: establishing a main arch three-dimensional shell element model based on a finite element unit, and importing the main arch three-dimensional model into the main arch three-dimensional shell element model;

[0095] Based on the finite element method, a three-dimensional shell element model of the main arch is established, and the three-dimensional model of the main arch is imported. The model surface is discretized into a triangular mesh, and the element set Set_elements and node coordinate set Set_nodes of different components are established. It should be noted that since the three-dimensional terrain model does not participate in the calculation of the bridge temperature field, the terrain grid size far exceeds the surface grid size of the bridge component.

[0096] S302: discretizing the surface of the main arch three-dimensional shell unit model into surface units of a triangular mesh, and establishing unit sets and node coordinate sets of different components;

[0097] S303: Obtain the solar altitude angle and azimuth at a certain moment, obtain the solar direction vector at that moment through the altitude angle and azimuth, determine whether any surface unit of the main arch is blocked by the terrain through the solar direction vector, and obtain the shadow area of ​​the main arch.

[0098] Specifically, judging whether any surface unit of the main arch is blocked by the terrain by the sun direction vector includes:

[0099] Obtain the three unit node coordinates of the surface unit scattered into a triangular mesh, through the three unit node coordinates;

[0100] The center point coordinates are projected along the sun direction vector to determine whether a projection point is formed at any position of the main arch three-dimensional shell unit model. If a projection point is formed, the surface unit is determined to be a shadow area at this moment. If no projection point is formed, the surface unit is determined to be a non-shadow area at this moment.

[0101] Specifically, the determining that the surface unit is a shadow area at this moment includes determining that the surface unit is a self-shadow area blocked by its own back surface, or an other-shadow area blocked by other components, including:

[0102] Calculate the element normal vector of the surface element through the three element node coordinates;

[0103] Calculate whether the dot product of the sun direction vector and the element normal vector is less than or equal to 0. If it is less than or equal to 0, the surface element is divided into a self-shadow area. If it is greater than 0, the center point of the surface element is obtained through the element node coordinates.

[0104] A ray is established through the center point and the sun direction vector, and the intersection of the ray and any plane is taken as the starting point. Three vectors l1, l2, and l3 are constructed with three unit nodes as the end points, and the cosine values ​​of the angles between the vectors are calculated. The angles of the three vectors with three unit nodes as the end points are α1, α2, and α3.

[0105] cosα1=dot(l1,l2) / (norm(l1)*norm(l2))

[0106] cosα2=dot(l2,l3) / (norm(l2)*norm(l3))

[0107] cosα3=dot(l3,l1) / (norm(l3)*norm(l1))

[0108] If the cross product directions of these vectors are the same, that is, cosα11=cosα2=cosα3=1, then the surface unit is judged as a shadow area; if they are different, then it is judged as a non-shadow area.

[0109] In this example, you can also make a judgment by following the steps below:

[0110] If the projection point is within the spatial plane formed by a certain topographic unit, it means that the sunlight shining on the surface of the bridge unit is blocked by the topographic unit.

[0111] The blocked bridge surface units are added to the set Set_bri_Mo1. Next, the set Set_bri of bridge surface units is subtracted from the set Set_bri_Mo1 of bridge surface units blocked by topography, so as to obtain the set Set_bri_part of bridge surface units not blocked by topography.

[0112] Further, determine whether the bridge unit surface unit set Set_bri_part is blocked by its own back side, and compare the angle between the outer normal vector of the unit surface and the sun direction vector. If the angle is greater than or equal to 90°, it means that the light is incident from the opposite direction, and the unit surface is blocked by its own back side. Add these units to the self-shadow set Set_bri_So.

[0113] Furthermore, a subtraction is made between the set of all units Set_bri_part contained in the bridge and the set of self-shadowing Set_bri_So, so as to obtain the set of bridge surface units Set_bri_part2 that is not blocked by its own rods.

[0114] Furthermore, to determine whether the unit surface in the Set_bri_part2 set is blocked by other bridge components, the following steps can be followed:

[0115] Use the three node coordinates of the surface unit in the Set_bri_part2 set to calculate the center point coordinates of the bridge surface unit coord_cen_bri2_i;

[0116] Project the coordinates of the center point along the sun direction vector, and the projection point should fall on the space plane formed by the remaining units in the Set_bri_part2 set except this unit.

[0117] If the projection point is within the spatial plane formed by one of the remaining units, it means that the sunlight shining on the surface of the bridge unit is blocked by other components.

[0118] The blocked bridge surface units are added to the set Set_bri_Mo2. Next, the set Set_bri_part2 of bridge surface units is subtracted from the set Set_bri_Mo2, thus obtaining the bridge surface illumination unit set Set_bri_No.

[0119] Through the above steps, the bridge surface units that are blocked by terrain, blocked by their own back, blocked by other components, and under light are divided into different sets.

[0120] An exemplary embodiment of the present invention, referring to Figure 9-10As shown, obtaining real-time meteorological data of the main arch at different time periods includes setting a second UAV flight route, and the second UAV flight route includes:

[0121] S401: Determine an arch rib type of the bridge, where the arch rib type includes a single arch rib and multiple arch ribs;

[0122] S402: When the arch rib type is determined to be a single arch rib, a signal is sent to cause the UAV to fly along the outer side of the arch rib parallel to the arch rib axis;

[0123] Specifically, first, the flight route of the UAV is established, and according to the position of the arch rib axis in the coordinate system, the main flight route along the outer side of the arch rib parallel to the arch rib axis is set. According to the span of the bridge and the precise requirements of the temperature field calculation, the number of stop points Po,i is set on the main flight route.

[0124] After that, after self-checking, the drone was equipped with a high-definition camera and a portable meteorological detector, took off from the arch foot on one side, and flew to point Po,1 along the set main flight route. After confirming the coordinates of point Po,1, it stopped and collected horizontal solar radiation, temperature, wind speed and other relevant data samples, while recording the collection time and altitude. Then it continued to fly to the next stop point Po,2 until it reached the arch foot on the other side. The measurement plan covers round trip flights, with two stops and measurements at each stop point.

[0125] S403: When the rib type is determined to be multiple ribs, a signal is sent to cause the drone to perform an alternating up and down zigzag flight along the outer side of the rib parallel to the rib axis.

[0126] Steel tube concrete truss arch bridges usually have many rods and contain two arch rib axes in the vertical direction. Stop points are arranged on these two axes respectively, and the flight route of the drone is set in a Z shape. The flight starts from the arch foot on one side, first reaches the stop point Po,d1 of the lower chord arch rib and stops and hovers. After collecting meteorological data, it moves vertically to the stop point Po,u1 of the corresponding upper chord arch rib and stops and hovers again to collect meteorological data. Then it pitches over this point and goes to the stop point Po,d2 of the next lower chord arch rib until it reaches the arch foot on the other side. The measurement plan covers round trip flights, and each stop point is used for two stops and meteorological data collection.

[0127] In addition, for key cross-sectional locations other than the arch ribs, secondary flight routes are set, and the UAV reaches the stop point through hovering, vertical, pitch, roll, and yaw movements to complete meteorological data collection.

[0128] After the drone flight data collection is completed, it returns to the drone take-off and landing platform set up near the arch foot and transmits the data back for analysis.

[0129] Taking into account the time-varying characteristics of solar radiation, air temperature and wind speed, the flight and sampling frequencies are reasonably set according to the meteorological change rate near the bridge site.

[0130] In an exemplary embodiment of the present invention, obtaining the heat flux density of the main arch surface unit includes:

[0131] S501: Obtain theoretical heat flux density through the Dilger model and the angle of the sun's rays;

[0132] Direct solar radiation refers to the radiation energy of sunlight that directly shines on the ground through the atmosphere. The intensity of this radiation depends on factors such as the altitude angle of the sun, atmospheric transparency, cloud cover, and the altitude of the ground. Scattered solar radiation refers to the solar radiation that scatters with gases, dust, and aerosols in the atmosphere when passing through the atmosphere, and eventually reaches the ground in the form of solar radiation from all directions in the sky. The intensity of this radiation is mainly determined by factors such as the incident angle of solar radiation and atmospheric conditions. In the illuminated area, the total solar radiation received by the bridge surface unit includes direct solar radiation, scattered radiation, and ground reflection. In the shadow area, the total solar radiation received by the bridge surface unit only includes scattered radiation and ground reflection. The Dilger solar radiation model is used to calculate the direct solar radiation received by the bridge surface.

[0133] S502: Obtain the direct solar radiation value in the real-time meteorological data, define the error function, and find the adjustment coefficient that minimizes the error function E through the least square method;

[0134] S503: Scale the theoretical heat flux density of each observation point according to the adjustment coefficient to obtain a corrected heat flux density.

[0135] According to the Dilger model, the intensity of direct solar radiation is related to the atmospheric transparency coefficient P on a sunny day, the atmospheric absorption constant tu, and the relative atmospheric pressure at the bridge site. Using the measured meteorological data in the bridge site area obtained by drones at different time periods, the atmospheric absorption constant tu can be inferred and the empirical parameters in the Dilger model can be further corrected.

[0136] Secondly, the heat flux density of the bridge surface unit Set_bri is calculated based on the Dilger model and the angular relationship between the components and the sun's rays. This heat flux density is the theoretical value qcal,i calculated by the model under clear weather conditions, but the effect of cloud thickness on direct solar radiation has not been considered. The adjustment factor k is introduced to consider the effect of cloud thickness on direct solar radiation.

[0137] In the third step of the flight control system, the horizontal solar direct radiation qtest,i collected by the drone on the flight route at different cross-section positions of the bridge is compared with the theoretical value qcal,i calculated by the model at this point, and an error function E is defined, which is the sum of the squares of the errors of all measuring points. The least squares method is used to find the parameters that minimize the error function E, that is, the overall adjustment coefficient k. Assuming that the adjustment coefficients of all measuring points are the same, the overall adjustment coefficient k is determined by minimizing the error function E. Then, the calculated theoretical heat flux density of the bridge surface unit is adjusted by scaling the calculated value of each measuring point according to k.

[0138] Specific:

[0139]

[0140] k=(X T X) -1 X T Y

[0141] Where f(x) is the calculated theoretical value of the model at each point, E is the defined error function, X is the data matrix observed by the UAV, Y is the calculated theoretical value vector corresponding to f(x), and k is the coefficient vector to be obtained.

[0142] Since the present invention adopts more empirical formulas or coefficients for calculation, it is necessary to compare and verify the data of each parameter adopted. The main function of the data verification module is to compare whether the parameter values ​​adopted in the clear sky model are accurate.

[0143] Specifically, the heat flux density data is acquired and compared with the total solar radiation on the horizontal plane to verify whether the parameter values ​​used in the clear sky model are accurate. For the heat flux density calculation value, this data verification module needs to set the system threshold β, and substitute the heat flux density calculation value obtained by the drone collection data and the shadow recognition module into the following formula to calculate the relative error.

[0144]

[0145] Where α is the relative error, q2 is the calculated value of heat flux, and q1 is the total solar radiation on the horizontal plane.

[0146] If the error is within the system threshold range, the calculation and analysis module can be entered. If the error is outside the system threshold range, the parameter values ​​used in the aforementioned clear sky model calculation need to be corrected until the relative error between the calculated value of the total solar radiation on the horizontal plane and the data value collected by the solar radiation sensor is within the threshold β range.

[0147] In the second aspect, a data acquisition and analysis system for a large-span steel tube concrete main arch includes:

[0148] A three-dimensional model building module is configured to obtain point cloud data of the topography where the main arch is located, and to build a three-dimensional point cloud model through the point cloud data;

[0149] A shadow recognition module is configured to calculate the shadow area of ​​the main arch within the acquisition period based on the three-dimensional point cloud model;

[0150] The solar radiation model calculation module is configured to obtain the non-shadow area based on the shadow area, obtain the real-time meteorological data of the main arch at different time periods at several observation points, and obtain the heat flux density of the surface unit of the main arch based on the real-time meteorological data and the Dilger model;

[0151] The temperature field analysis module is configured to obtain the temperature distribution of the main arch surface through the heat flux density, obtain the initial temperature of the main arch, and obtain and output the temperature stress of the main arch section through the temperature distribution and the initial temperature of the main arch;

[0152] A main control device is connected to the three-dimensional model building module, the shadow recognition module, the solar radiation model calculation module and the temperature field analysis module, and is used to execute the above-mentioned large-span steel tube concrete main arch data collection and analysis method.

[0153] In a third aspect, a data collection and analysis device for a large-span steel tube concrete main arch includes a drone;

[0154] The UAV is provided with a meteorological data collection device and a processing unit, and the processing unit is connected to the meteorological data collection device and the UAV 5, and is used for the above-mentioned method for collecting and analyzing data of a large-span steel tube concrete main arch;

[0155] The meteorological data collection device comprises a wind speed measuring instrument 1 , a wind direction measuring instrument 2 , a solar radiation sensor 3 and a temperature sensor 4 .

[0156] The anemometer 1, the wind direction meter 2, the solar radiation sensor 3 and the temperature sensor 4 are all fixed on the meteorological parameter collection mechanism bracket, which is made of light-weight steel such as carbon steel. The structure can be hollowed out to further reduce the weight and facilitate the movement of the drone 5.

[0157] The UAV includes a power device, a bracket fixing bolt is arranged on the top of the UAV, which is used to fix the meteorological parameter collection mechanism, a processing unit is arranged at the rear of the UAV, a high-definition camera 6 is arranged in front of the UAV to provide a convenient field of vision for the UAV operator, and the camera can store video recordings, and a meteorological parameter collection mechanism power supply is arranged under the UAV to supply power to the sensors arranged on the meteorological parameter collection mechanism.

[0158] The meteorological collection mechanism bracket is a device for connecting the drone to the meteorological sensor. The structure is composed of a T-shaped bracket, and 4 holes are evenly arranged at the top for fixing various meteorological parameter sensors.

[0159] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0160] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. The computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0161] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A data collection and analysis method for a large-span steel tube concrete main arch, characterized in that: include: Obtain point cloud data of the topography where the main arch is located, establish a three-dimensional point cloud model through the point cloud data, and calculate the shadow area of ​​the main arch during the acquisition period based on the three-dimensional point cloud model; Based on the shadow area, the non-shadow area is obtained, the real-time meteorological data of the main arch at different time periods at several observation points are obtained, and the heat flux density of the surface unit of the main arch is obtained based on the real-time meteorological data and the Dilger model; The temperature distribution on the main arch surface is obtained through the heat flux density, the initial temperature of the main arch is obtained, and the temperature stress of the main arch section is obtained and output through the temperature distribution and the initial temperature of the main arch.

2. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 1 is characterized in that: The establishing of a three-dimensional point cloud model through point cloud data comprises: Determine the scope of the target area and set the control points for collecting point cloud data, determine the layout parameters of the collection base station and set the flight route of the first UAV, and use the UAV to collect image data at the location of the collection base station; Set the heading overlap rate and lateral overlap rate, and set the flight altitude limit function of the drone through the heading overlap rate; The main arch is located at a location where three-dimensional modeling is performed on the spot to obtain a three-dimensional model of the main arch, the collected image data is obtained, and a three-dimensional point cloud model with real coordinate information is synthesized through the image point coordinates and control points in the overlapping area of ​​the image data.

3. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 2 is characterized in that: The function for setting the flight altitude limit of the drone includes: Where H is the flight altitude of the UAV, Δx is the terrain height difference, and O is the heading overlap rate.

4. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 3 is characterized in that: The shadow distribution area of ​​the main arch during the acquisition period includes: Establishing a three-dimensional shell unit model of the main arch based on a finite element unit, and importing the three-dimensional model of the main arch into the three-dimensional shell unit model of the main arch; Discretize the surface of the main arch three-dimensional shell unit model into surface units of triangular meshes, and establish unit sets and node coordinate sets of different components; The solar altitude angle and azimuth at a certain moment are obtained, and the solar direction vector at that moment is obtained through the altitude angle and azimuth. The solar direction vector is used to determine whether any surface unit of the main arch is blocked by the terrain and the shadow area of ​​the main arch is obtained.

5. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 4 is characterized in that: The step of judging whether any surface unit of the main arch is blocked by the terrain by using the sun direction vector comprises: Obtain the three unit node coordinates of the surface unit scattered into a triangular mesh, through the three unit node coordinates; The center point coordinates are projected along the sun direction vector to determine whether a projection point is formed at any position of the main arch three-dimensional shell unit model. If a projection point is formed, the surface unit is determined to be a shadow area at this moment. If no projection point is formed, the surface unit is determined to be a non-shadow area at this moment.

6. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 5 is characterized in that: The determining that the surface unit is a shadow area at this moment includes determining that the surface unit is a self-shadow area blocked by its own back surface, or an other-shadow area blocked by other components, including: Calculate the element normal vector of the surface element through the three element node coordinates; Calculate whether the dot product of the sun direction vector and the element normal vector is less than or equal to 0. If it is less than or equal to 0, the surface element is divided into a self-shadow area. If it is greater than 0, the center point of the surface element is obtained through the element node coordinates. A ray is established through the center point and the sun direction vector, the intersection of the ray and any plane is taken as the starting point, and three vectors are constructed with three unit nodes as the end points. After cross-producting the three vectors, it is determined whether the directions are the same. If they are the same, the surface unit is judged as the shadow area, if not, it is judged as the non-shadow area.

7. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 5 is characterized in that: The obtaining of real-time meteorological data of the main arch at different time periods includes setting a second UAV flight route, wherein the second UAV flight route includes: Determine the arch rib type of the bridge, wherein the arch rib type includes a single arch rib and multiple arch ribs; When the arch rib type is determined to be a single arch rib, a signal is sent to make the UAV fly along the outer side of the arch rib parallel to the arch rib axis; When the rib type is determined to be multiple ribs, a signal is sent to cause the drone to fly in a zigzag pattern along the outer side of the rib parallel to the rib axis, alternating up and down.

8. The method for data collection and analysis of a large-span steel tube concrete main arch according to claim 5 is characterized in that: The obtaining of the heat flux density of the main arch surface unit comprises: The theoretical heat flux density is obtained through the Dilger model and the angle of the sun's rays; Obtain the direct solar radiation value in the real-time meteorological data, define the error function, and find the adjustment coefficient that minimizes the error function E through the least squares method; The theoretical heat flux density at each observation point is scaled according to the adjustment coefficient to obtain the corrected heat flux density.

9. A data acquisition and analysis system for a large-span steel tube concrete main arch, characterized in that: include: A three-dimensional model building module is configured to obtain point cloud data of the topography where the main arch is located, and to build a three-dimensional point cloud model through the point cloud data; A shadow recognition module is configured to calculate the shadow area of ​​the main arch within the acquisition period based on the three-dimensional point cloud model; The solar radiation model calculation module is configured to obtain the non-shadow area based on the shadow area, obtain the real-time meteorological data of the main arch at different time periods at several observation points, and obtain the heat flux density of the surface unit of the main arch based on the real-time meteorological data and the Dilger model; The temperature field analysis module is configured to obtain the temperature distribution of the main arch surface through the heat flux density, obtain the initial temperature of the main arch, and obtain and output the temperature stress of the main arch section through the temperature distribution and the initial temperature of the main arch; A main control device, which is connected to the three-dimensional model building module, the shadow recognition module, the solar radiation model calculation module and the temperature field analysis module, and is used to execute a large-span steel tube concrete main arch data collection and analysis method as described in any one of claims 1-8.

10. A data collection and analysis device for a large-span steel tube concrete main arch, characterized in that: Including drones; The UAV is provided with a meteorological data collection device and a processing unit, and the processing unit is connected to the meteorological data collection device and the UAV, and is used to execute the data collection and analysis method for a large-span steel tube concrete main arch according to any one of claims 1 to 8; The meteorological data collection device includes a wind speed meter, a wind direction meter, a solar radiation sensor, and a temperature sensor.

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