JP7534583B2 - Method and device for measuring porosity of material surface - Google Patents

Description

The present invention relates to a method and device for measuring the porosity of a material surface, and in particular to a method and device for measuring the porosity of the surface of a concrete base for seismic isolation.

In recent years, there has been an increasing need for seismic isolation structures that prevent earthquake vibrations from being directly transmitted to buildings by installing seismic isolation devices such as laminated rubber between the building and the foundation. As shown in Figure 1, a seismic isolation device 1 is connected to an upper structure 3 and a seismic isolation foundation 4 via steel plates called base plates 2 installed above and below.
During construction, in order to integrate the base plate 26 with the structure, it is necessary to pour concrete 512 with the base plate 2 installed as shown in Figure 2. At this time, the concrete 4 for the lower seismic isolation foundation must be poured so that no gaps are formed on the surface 4a of the concrete for the lower seismic isolation foundation of the base plate, but it is not possible to remove the base plate for each seismic isolation foundation to check the filling status.
Therefore, prior to the actual construction, a full-scale construction test is carried out to check whether the filling rate target set by the designer is met, thereby confirming that there are no flaws in the planned construction plan. In this construction test, the base plate is removed from the test specimen and the void ratio of the surface layer of concrete underneath is calculated. If the void ratio is below the specified value, the validity of the construction plan is confirmed and the start of actual construction is approved.

Published Patent Publication No. 2018-71125

Obayashi Corporation Technical Research Institute Report No. 83 2019 Obayashi Corporation

When mounting the vibration isolation device 1 on the concrete base 4, it is necessary to cast the base plate 2 for mounting the device on the concrete base 4. In actual construction, as shown in the cross-sectional view of the method of pouring concrete under the base plate in Figure 2, the reinforcement is surrounded by a formwork 6, and concrete 5 is poured from an opening in the center of the base plate 2 placed on the reinforcement. However, if the filling rate of the concrete surface 4a2 is low, there is a possibility that the vertical load cannot be efficiently transmitted to the concrete base 4. Generally, a filling rate of 90 to 95% is required. In order to measure the filling rate, the base plate 2 must be removed once and the total area of the filling leakage, so-called void 8, must be measured.
Conventional methods for calculating the filling rate have mainly involved manual work, such as visually detecting voids, coloring them with felt-tip pens, and measuring the colored areas with a ruler. This posed challenges to the work process, as it took several days to measure a one-meter square earthquake-resistance foundation concrete structure, for example.

In order to solve the above problems, the present invention uses a three-dimensional surface shape measuring means using light as described below.
First, the surface of the concrete base isolation foundation, which is the measurement target, is measured with an optical 3D measurement device, and the surface shape is converted into digital data. Next, the data is processed with dedicated analysis software to calculate the required void ratio. The 3D measurement device used in this case adopts a measurement principle called the structured light method, and guarantees the necessary and sufficient measurement accuracy.

According to the porosity measurement method and device of the present invention, the measurement results of the porosity of the surface of the concrete base isolation foundation can be output in a few seconds to a few tens of minutes, which leads to a significant improvement in work efficiency, and as a result, contributes to shortening the measurement work process and reducing costs. Furthermore, the accuracy of porosity calculation is improved by improving the reliability of the basic data for porosity calculation, and there is also an effect that visualization and recording as digital data are improved. Furthermore, since the method and device of the present invention are characterized by being non-contact and non-invasive with respect to the measurement object, there is also an effect that the measured surface is not soiled or damaged.

Cross-section of the seismic isolation foundation Cross-sectional view of concrete pouring method for the bottom of the base plate An explanatory diagram of scanning the surface of the seismic isolation foundation concrete with a 3D shape measurement device Measurement workflow 3D data of void distribution Color map display of 3D void distribution data Displaying analysis results on a map Quantified porosity detection results

The following describes an embodiment of the present invention with reference to the drawings. Note that in the following description, the same components are given the same reference numerals and the description is omitted.

Figure 3 is an explanatory diagram of one embodiment in which the measurement method and device 3 according to the present invention is applied to measuring the porosity of the concrete surface 4a of the seismic isolation foundation shown in Figure 2. A measurement worker 9 holds the measurement device 10 and scans the concrete surface 4a to be measured. Since the range 4 that can be measured in one scan with the measurement device 10 is about A4 size, the data from multiple scans is generally automatically stitched together on a PC to complete the data for the entire concrete surface 4a that needs to be measured. Figure 4 shows a flow chart of the measurement work according to this embodiment.

Next, we will explain a specific measurement example of a concrete surface 4a with a measurement range of 400 mm horizontal and 150 mm vertical. In this example, we set it so that dents less than 0.5 mm deep are ignored. This is because in this type of construction, the smoothness of the concrete surface 4a is usually kept to 0.5 mm or less. Also, even if the smoothness of the concrete surface 4a is 0.5 mm or more, it can be ignored if the relative depth is less than 0.5 mm compared to the reference surface calculated from the local surface surrounding the void.

When the concrete surface 4a having voids is scanned and measured by the measuring device 10 of this embodiment, the three-dimensional surface shape data shown in Figure 5 is obtained. Next, the data is numerically processed by the software installed on the PC, and the depth of the recesses due to the voids is displayed as a color map, as shown in Figure 6. The color bar on the right side of this figure indicates depths of 0.5 mm or more to 3.92 mm. Furthermore, the void depth data in this figure is divided into a grid of 2.5 mm vertically and horizontally, and output as CSV data. Figure 7 shows a map display of the analysis results in which recesses with a depth of 0.5 mm or more and a horizontal length of 5 mm or more are colored red using Excel's VBA function. The specific method of selecting effective voids is to search for cells in each row from left to right that also have data of a depth of 0.5 mm or more, and only if the cell to the right of that cell is 0.5 mm or more, the corresponding cell is colored red and counted as the corresponding void. When the work on one row is completed, the work is moved to the row below and the same work is repeated. As a result, the number of void cells with a depth of 0.5 mm or more and a length of 5 mm or more, i.e., the area, can be determined. Figure 8 shows the porosity quantified from the detection results in Figure 7.

In the above embodiment, the measurement of the surface of concrete is described as the measurement target, but it goes without saying that the material surface to which the present invention can be applied is not limited to a concrete surface.

According to the method and device for measuring the porosity of a material surface of the present invention, the degree and number of dents on the measured surface can be measured quickly, quantitatively, and objectively, so that it can be effectively used in the civil engineering and construction fields where concrete is often used. Furthermore, since the material surfaces to which the method and device of the present invention can be applied are not limited to concrete surfaces, it can be used to measure the number of dents on asphalt road surfaces, and to measure the distortion of bricks and peeling of tiles on the walls of structures, etc.

1 Vibration isolation device 2 Base plate 3 Upper structure 4 Vibration isolation foundation concrete 4a Vibration isolation foundation concrete surface 5 Poured concrete 5a Concrete pouring direction 6 Formwork 7 Hopper 8 Gap 9 Measurement worker 10 Three-dimensional shape measurement device 11 Single-shot scan area 12 Measurement projection light 13 Total measurement area 14 Upper structure

Claims (1)

When calculating the porosity of the concrete surface of the seismic isolation foundation,
(1) measuring the surface using an optical three-dimensional shape measurement technique having a resolution of 0.5 mm or less to obtain three-dimensional coordinate data;
(2) analyzing the three-dimensional coordinate data to obtain a depth value of a recess due to a void;
(3) dividing the depth values into a grid of 2.5 mm length and width and outputting representative values as a data file in CSV format;
(4) loading the output CSV data file into spreadsheet software such as Excel, and using a VBA function, coloring only cells that are 0.5 mm deep or more and have two or more adjacent cells in a row, and counting the number of such cells;
(5) A step of calculating the porosity by dividing the number of colored cells by the number of cells (number of grids) in the entire CSV data;
A method for calculating the porosity of a surface of seismic isolation foundation concrete, comprising: