A method for controlling elevation measurement of prefabricated columns

Abstract

The invention relates to a height measurement and control method for prefabricated column installation. The method adopts a measuring instrument consisting of a level, a tower ruler and a tripod, and uses a polyfluorocarbon plate to increase the height. The specific operation steps are as follows: first, a plurality of polyfluorocarbon plate small components with different thicknesses are prepared to fully utilize the structural characteristics of the polyfluorocarbon plate; second, a base surface within the joint range of the hoisting column is roughened, and polyfluorocarbon plate components with the same thickness are placed at the center position and four corners of the positioning plate; third, the elevations of the polyfluorocarbon plates at five positions are measured, and the height differences between them are calculated. The thickness of the polyfluorocarbon plates is increased or decreased to control the height differences at each point to meet the specification requirements; finally, the prefabricated column is hoisted, and the verticality deviation is observed on two vertical planes. The polyfluorocarbon plates are increased or decreased at reasonable points according to the verticality deviation to indirectly control the elevation until the verticality of the center line of the prefabricated column meets the specification requirements, thereby completing the installation of the prefabricated column.

Description

Technical Field

[0001] The invention relates to an elevation measurement control method for prefabricated column installation, belongs to the field of elevated bridge construction, and is suitable for a measurement method during prefabricated column installation. Background Art

[0002] With the continuous emergence of four new technologies, elevated bridge construction is becoming increasingly factory-based and modularized, with prefabrication technology now widely used in actual projects. Prefabrication involves moving the traditional on-site concrete pouring process to a fabrication plant. On-site components are then modularly manufactured in a 1:1 design scale at the factory and then transported to the site for assembly like building blocks, enabling rapid, environmentally friendly bridge construction.

[0003] However, when installing and positioning prefabricated columns at the construction site, especially during the elevation measurement and control process, if only traditional level observations are performed, due to the limitations of the construction space and the inconvenience of frequent mobile measurements, there are certain limitations in the operation process. This traditional measurement work is heavy in workload, time-consuming, and has great safety risks. There are many factors that cause measurement errors, which is not conducive to the overall prefabricated column installation process and the accuracy control is also slightly inferior. Summary of the Invention

[0004] The present invention aims to solve the limitations of the above-mentioned measurement methods and provide a method to assist traditional leveling measurement, thereby achieving fast and high-precision measurement guarantees and accelerating construction progress.

[0005] To achieve the above-mentioned purpose, the technical solution of the present invention is: a method for measuring and controlling the elevation of prefabricated columns, which uses a measuring instrument consisting of a level, a tower ruler, and a tripod, supplemented by a PTFE plate to increase and adjust the elevation. The specific operating steps are as follows:

[0006] (1) Prepare several pieces of PTFE sheets with a thickness of 1 mm to 5 mm;

[0007] (2) The range of the platform positioning plate is roughened. In the roughened area, the center and four corners are selected and small PTFE plate components of the same thickness are placed. The center should be 2mm thicker than the four corners.

[0008] (3) Set up the level, level it, ensure that it is stable and its height is not affected by external environment;

[0009] (4) Observe the elevations of the five padding points and calculate the height differences between them. Based on the principle that the center point is 2mm higher than the four corners and the four corners are level, adjust the five elevation points. The height difference is adjusted by increasing or decreasing the thickness of the PTFE plate. The elevation adjusted at this time is the elevation reference plane for the subsequent prefabricated column installation. It must be adjusted in place to ensure the level of the reference plane.

[0010] (5) Lower the prefabricated column and insert the reserved steel bars, observe the plumb state of the center line on the two vertical surfaces of the column, and add or remove the PTFE plate at reasonable points according to the verticality deviation to indirectly control the elevation until the verticality of the center line of the prefabricated column meets the requirements of the specification, and the installation of the prefabricated column is completed.

[0011] Furthermore, in step (2), a 5 mm thick PTFE plate is placed at the center of the roughened area, and a 3 mm thick PTFE plate is placed at the four corners.

[0012] Furthermore, in step (5), when the side of the column that is tilted indicates that the elevation is too low, the conventional level elevation measurement cannot be performed due to the limited measurement space. For the lower side, the deficiency is compensated by padding with PTFE sheets; the verticality is repeatedly observed, and the number of PTFE sheets is increased or decreased at appropriate positions to finally complete the installation and positioning of the column.

[0013] Furthermore, the thickness of the PTFE plate is selected according to the actual height difference, and the thickness specifications include 1mm, 2mm, and 4mm, which can meet the accuracy requirement of the level instrument observation to 1mm.

[0014] Compared with conventional technologies, the present invention has the following advantages and effective results:

[0015] This invention utilizes traditional leveling methods, supplemented by the addition of a PTFE plate component, to overcome the limitation of being unable to measure elevation after the columns are lowered, enabling rapid and accurate installation of prefabricated columns. This overcomes the drawback of the level's limited sightline height and avoids the significant errors that can occur with other indirect elevation measurement methods, saving time while ensuring accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the placement of the PTFE sheet in the roughened area;

[0017] Figure 2 It is a schematic diagram of the traditional method of measuring the elevation of the datum surface;

[0018] Figure 3 This is a schematic diagram of the installation of prefabricated columns with limited elevation measurement and the assistance of PTFE plates;

[0019] Figure 4 It is a flow chart of the elevation measurement control method for prefabricated column installation. DETAILED DESCRIPTION

[0020] The invention will be described in further detail below with reference to the accompanying drawings.

[0021] like Figures 1 to 3 As shown, a method for controlling elevation measurement for prefabricated column installation employs a conventional level 1, a tripod 2, a tower ruler 3, and PTFE sheet spacers 4. When equipping the PTFE sheet spacers 4, sufficient quantities should be provided according to different thicknesses, and multiple pieces of the same thickness should be used.

[0022] like Figure 1 、 Figure 4 As shown in the figure, the operating steps of the elevation measurement control method for prefabricated column installation are as follows:

[0023] First, calibrate the measuring instruments. When preparing for on-site measurement, the geometric dimensions of the prefabricated columns entering the site must be inspected for quality, and center lines must be drawn on the two vertical surfaces, scale strips must be affixed, and markings must be made.

[0024] The surface of the pedestal within the reserved reinforcement of the limit plate is roughened. The density of the roughening points and the size of the holes must be uniform and appropriate, and not too rough. After the roughening is completed, the loose dust and concrete debris are blown away with a blower to create a gap for the grouting. The pedestal and column can be connected together with high-strength grouting material to form a whole.

[0025] like Figure 1 As shown, a 5mm thick PTFE plate is placed in the center of the roughened area, and a 3mm thick PTFE plate is placed in the four corners. The thickness of the pad should be composed of several pieces of smaller thickness, and cannot be set with a pad of exactly the right thickness.

[0026] like Figure 2 As shown, the ordinary leveling method is used to measure the PTFE plate pad, and the relative elevation measurement is adopted, so there is no need to perform backsight elevation orientation of the benchmark point.

[0027] Calculate the height difference of the measured elevation values, primarily the difference between point 1 and the remaining points, and the difference between the remaining points. First, select a corner point as a reference, then adjust the other three intersection points, adding or removing PTFE plates based on the height difference. Once the four corners are parallel, remeasure again. If the deviation is zero, adjust point 1 so that it is 2mm higher than the four corners. After adjustment, remeasure again to ensure the height difference remains within the requirements of 2mm and zero. This elevation plane serves as the reference surface.

[0028] like Figure 3As shown, the prefabricated columns are lowered for installation and positioning. After the prefabricated columns are lowered, there is no space on the support surface for a ruler, making direct elevation measurement impossible. The previously leveled reference surface will deform under the weight of the columns, and only a standard horizontal surface can ensure the plumb state of the prefabricated columns. Therefore, the use of PTFE sheets as underlayments is used to indirectly measure and control elevation.

[0029] Observe the verticality of the column surface using the principle of a plumb bob or theodolite's vertical axis. A tilted side of the column indicates a low elevation below, which can be adjusted by padding with PTFE sheeting. Repeatedly observe both sides of the prefabricated column several times, and adjust the elevation indirectly by increasing or decreasing the thickness of the PTFE sheeting accordingly.

[0030] After two or three repetitions, the elevation is adjusted to the correct position. The center lines of the two prefabricated columns are plumb, the PTFE sheeting under the columns is horizontal, and the height difference between them is zero, completing the installation, positioning, measurement, and control of the prefabricated columns.

[0031] The above-described method is only a description of the preferred implementation of the present invention and does not limit the scope of the present invention. Any substitution of materials or other defined description methods based on the principle of the technical method of the present invention should not be excluded from the scope of protection of the present invention.

Claims

1. A method for controlling elevation measurement for prefabricated column installation, characterized in that: Use a measuring instrument consisting of a level, a tower ruler, and a tripod, supplemented by a PTFE plate to increase and adjust the elevation. The specific operating steps are as follows: (1) Prepare several pieces of PTFE sheets with a thickness of 1 mm to 5 mm; (2) Roughen the range of the platform positioning plate, select the center and four corners of the roughened area, and place small PTFE plate components of the same thickness. The center should be 2mm thicker than the four corners. (3) Set up the level, level it, ensure that it is stable and its height is not affected by external environment; (4) Observe the elevations of the five padding points and calculate the height differences between them. Based on the principle that the center point is 2mm higher than the four corners and the four corners are level, adjust the five elevation points. The height difference is adjusted by increasing or decreasing the thickness of the PTFE plate. The elevation adjusted at this time is the elevation reference plane for the subsequent prefabricated column installation. It must be adjusted in place to ensure the level of the reference plane. (5) Lower the prefabricated column and insert the reserved steel bars, observe the plumb state of the center line on the two vertical surfaces of the column, and add or remove the PTFE plate at reasonable points according to the verticality deviation to indirectly control the elevation until the verticality of the center line of the prefabricated column meets the requirements of the specification, and the installation of the prefabricated column is completed.

2. The elevation measurement control method for prefabricated column installation according to claim 1, characterized in that: In step (2), a 5 mm thick PTFE plate is placed at the center of the roughened area, and a 3 mm thick PTFE plate is placed at the four corners.

3. The elevation measurement control method for prefabricated column installation according to claim 1, characterized in that: In step (5), when the side of the column that has fallen down indicates that the elevation is too low, the conventional level elevation measurement cannot be performed due to the limited measurement space. For the lower side, PTFE sheets are used to make up for the shortfall. The verticality is repeatedly observed, and the number of PTFE sheets is increased or decreased at appropriate positions to finally complete the installation and positioning of the column.

4. The elevation measurement control method for prefabricated column installation according to claim 1, characterized in that: The thickness of the PTFE plate is selected according to the actual height difference, and the thickness specifications include 1mm, 2mm, and 4mm, which can meet the accuracy requirement of the level instrument observation to 1mm.

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