Construction quality management device and construction defect detection method

Abstract

To provide a construction quality management device and a construction defect detection method that improve work efficiency in quality management in compaction construction of the earth work.SOLUTION: A construction quality management device 100B (100) for managing construction quality in compaction construction includes a compaction machine 1 and a grounding resistance meter 5. The grounding resistance meter 5 includes grounding electrodes 51A-51D (51) and an auxiliary electrode 52. The grounding electrodes 51A-51D (51) are rear wheels 4a-4d (4) or a front wheel 3 of the compaction machine 1 and the rear wheels 4a-4d (4) or the front wheel 3 have conductive properties. It is preferable that the grounding electrodes 51A-51D (51) are the rear wheels 4a-4d (4) and there are two or more rear wheels 4a-4d (4). It is preferable that the auxiliary electrode 52 is the front wheel 3.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a construction quality control device and a construction defect detection method. [Background technology]

[0002] In recent years, technological developments related to the rolling construction of earthworks have been progressing, and related inventions have also been made public. In the rolling construction of earthworks, importance is attached to the quality control of the layer to be rolled, and it is necessary to improve the detection accuracy of defective parts in order to prevent poor construction. In particular, for a water-impermeable layer made of crushed bentonite stone, when the layer thickness is thinly constructed at about 10 cm to 30 cm, the lack of water-impermeability due to insufficient layer density becomes noticeable, so there is a strong demand for improving the detection accuracy of defective parts. For example, Patent Document 1 discloses a soil quality measuring device that measures the resistivity of soil on the ground after it has been compacted by a compaction machine such as a road roller. In the invention of Patent Document 1, a total of four electrode parts attached to both ends of the left and right frame parts come into contact with the ground, and the resistivity of the soil is measured by the Wenner method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-138732 A Summary of the Invention [Problem to be solved by the invention]

[0004] The invention of Patent Document 1 has a problem in that since one measurement point is used for each of four electrode parts, the work efficiency is low when detecting construction defects over a wide area of ​​the layer to be compacted. From this perspective, an object of the present invention is to provide a construction quality control device and a construction defect detection method that improve the work efficiency of quality control in compaction construction of earthworks. [Means for solving the problem]

[0005] The present invention, which solves the above-mentioned problems, is a construction quality control device for managing construction quality in compaction construction, comprising a compactor and an earth resistance meter, the earth resistance meter having an earth electrode and an auxiliary electrode, the earth electrode being a rear wheel or a front wheel of the compactor, and the rear wheel or the front wheel being conductive. The present invention also relates to a construction defect detection method using the quality control detection device, the construction defect detection method including a first step of measuring the grounding resistance of the grounding electrode and a second step of detecting construction defects.

[0006] According to the present invention, since a ground electrode can be mounted on the front or rear wheel of the rolling machine, it is possible to measure the ground resistance of the part of the rolling area (two-dimensional) where the front or rear wheel comes into contact. Then, the rolling machine moves over the entire rolling area, so that the ground resistance of the entire rolling area can be measured. Furthermore, by identifying the locations where the measured values ​​of the ground resistance are relatively different, construction defects can be detected. Therefore, construction defects can be efficiently detected over a wide range of the layer to be rolled.

[0007] It is also preferable that the ground electrode is the rear wheel and that there are two or more rear wheels. This allows a ground electrode to be installed on each of two or more rear wheels, so the ground resistance can be measured for each ground electrode that is placed (lined up) in a different position. Therefore, if a relatively different ground resistance is measured for any of the two or more ground electrodes, it can be determined that there was a construction defect at the point where that ground electrode came into contact. In this way, by installing ground electrodes on two or more rear wheels, it is possible to narrow down the defective points.

[0008] It is also preferable that the ground electrode is the rear wheel and the auxiliary electrode is the front wheel. This allows the earth resistance to be measured while keeping the distance between the earth electrode and the auxiliary electrode constant even when the rolling machine is moving, reducing noise in the measured value and improving the accuracy of detecting defective areas. It is also preferable that the ground electrode is the rear wheel, and the auxiliary electrode is an auxiliary wheel of the compactor that is located forward of the front wheel. In this way, the distance between the ground electrode and the auxiliary electrode can be made larger than when the auxiliary electrode is the front wheel. Also, even if the rolling mill is moving, the ground resistance can be measured while keeping the distance between the ground electrode and the auxiliary electrode constant. This further reduces the noise contained in the measured value, and further improves the accuracy of detecting defective parts. It is also preferable that the auxiliary electrode is disposed outside the rolling area. This allows the distance between the ground electrode and the auxiliary electrode to be sufficiently large, thereby extremely reducing the noise contained in the measured ground resistance, and greatly improving the accuracy of detecting defective areas. Effect of the Invention

[0009] According to the present invention, it is possible to improve the work efficiency of quality control in compaction construction of earthworks. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram of a construction quality control device according to a first embodiment. [Diagram 2] 5A and 5B are explanatory diagrams of a construction quality control device according to a second embodiment, where (a) is a plan view and (b) is a side view. [Diagram 3] FIG. 11 is a configuration diagram of a ground electrode according to a second embodiment. [Figure 4] FIG. 11 is a configuration diagram of another example of the ground electrode of the second embodiment. [Diagram 5] FIG. 11 is a configuration diagram of an auxiliary electrode according to a second embodiment. [Figure 6] FIG. 11 is an explanatory diagram (1 / 2) of detection of poor construction in the second embodiment. [Figure 7] FIG. 11 is an explanatory diagram (2 / 2) of construction defect detection in the second embodiment. [Figure 8] FIG. 11 is a configuration diagram of a second example of the auxiliary electrode of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In each drawing, common or similar components are denoted by the same reference numerals, and duplicated explanations thereof will be omitted.

[0012] [First embodiment] <Configuration> FIG. 1 is an explanatory diagram of a construction quality control device of a first embodiment. The construction quality control device 100A (100) is a device that detects construction defects of a rolling target layer L in order to control the construction quality in rolling construction. The construction quality control device 100A includes a rolling machine 1 and a ground resistance meter 2. The rolling machine 1 is, for example, a combined roller. The rolling machine 1 includes a front wheel 3 and four rear wheels 4. The front wheel 3 is an iron wheel. The rear wheels 4 are rubber tires. The rear wheels 4 can be designed to be conductive, for example, by fitting a metal ring having an axial length substantially equal to the width of the tire to the tire (see FIG. 3). The rolling machine 1 performs rolling on the rolling target layer L without or with vibration, and compacts the rolling target layer L. The rolling target layer L is, for example, a water-impermeable layer constructed of bentonite crushed stone.

[0013] The earth resistance meter 2 is an instrument for measuring the electrical resistance between a grounded conductor and a ground surface. The earth resistance meter 2 includes a ground electrode 21, a voltage electrode 22, a current electrode 23, and a main body 24. The main body 24 is mounted on the rolling machine 1. The earth electrode 21 is a measurement electrode that can be grounded at a measurement position for the earth resistance. As shown in FIG. 1, the earth electrode 21 is a rear wheel 4, and can measure the earth resistance of the surface contact portion (measurement point) between the rolling target layer L and the rear wheel 4. More specifically, a total of four earth electrodes 21 can be prepared for each of the four rear wheels 4. The voltage electrode 22 is an auxiliary electrode that is arranged at a different position from the earth electrode 21. The current electrode 23 is an auxiliary electrode that is arranged at a different position from the earth electrode 21. The auxiliary electrode is grounded and is a type of earth electrode. The main body 24 is an information processing device that issues an instruction to start measuring the earth resistance, performs calculation processing related to the measurement, and displays the measurement results. Main body portion 24 is electrically connected to ground electrode 21, voltage electrode 22, and current electrode 23 by wiring 25, 26, and 27.

[0014] <Measurement method> The fall of potential method can be used to measure the earth resistance of the measurement point. When an AC voltage V [V] is applied from the earth electrode 21, a closed circuit is formed through the earth, and a current I [A] flows. Then, the earth resistance R between the earth electrode 21 and the current electrode 23 is EC =V / I[Ω] is obtained. Ground resistance R EC is the earth resistance R of the earth electrode 21 E In addition, the ground resistance R of the current electrode 23 C Therefore, the earth resistance R C Excluding ground resistance R E In order to obtain the voltage, a voltage electrode 22 is placed between a ground electrode 21 and a current electrode 23. A current I [A] flows, and a voltage V between the ground electrode 21 and the voltage electrode 22 is p If this is obtained, the earth resistance R of the earth electrode 21 E =V p / I can be obtained. Although there is a ground resistance of voltage electrode 22, it can be designed so that it does not affect the measurement by making the internal resistance of a voltmeter (not shown) installed relative to voltage electrode 22 sufficiently large to make the current flowing through voltage electrode 22 extremely small.

[0015] Moreover, the measured value of the earth resistance contains some noise. Here, the potential distribution appearing on the ground surface when a current is passed through an electrode buried in the ground exhibits the characteristic that the potential decreases the further away from the electrode, and becomes 0 [V] at the point of infinity. As shown in FIG. 1, the voltage electrode 22 and the current electrode 23 are placed on the ground outside the compaction area consisting of the compaction target layer L, and are sufficiently distant from the earth electrode 21. Therefore, the noise contained in the measured value of the earth resistance of the earth electrode 21 can be sufficiently reduced.

[0016] <Detection of construction defects> According to the inventor's findings, when constructing a water-impermeable layer using crushed bentonite stone, if vibration-free rolling is performed twice using a combined roller, the compaction degree can be increased to 90% or more, and the desired layer density can be achieved. Therefore, it is easy to achieve the desired density, and the quality control of the rolling work depends on the detection of defective parts. The rolling machine 1 runs on the layer L to be compacted along a predetermined running path and performs the rolling work. The method for detecting construction defects using the construction quality control device 100A includes a first step of measuring the ground resistance of the ground electrode 21 and a second step of detecting construction defects. The first and second steps are performed continuously during the running and at various points in the rolling area. By monitoring the change in the measured ground resistance of the ground electrode 21 over the entire rolling area, defective parts can be detected.

[0017] There are various types of construction defects. First, there is a first case where the ground contact area of ​​the measured point is different from that of a healthy point. The first case 1 is often caused by, for example, different layer densities causing different amounts of penetration of the rear wheels 4 into the compacted layer L, or different grain sizes of crushed stone causing different void conditions due to uneven stone. There is also a second case where the resistivity value of the ground ground is different from that of a healthy point. The second case is often caused by, for example, different layer densities or different layer materials (layer components). Although this cannot be said to be construction defects in general, even if the moisture content is different, the measured value of the ground resistance of the ground electrode 21 is different, so the relevant point can be detected.

[0018] <Summary of the First Embodiment> According to the first embodiment, the ground electrode 21 can be mounted on the rear wheel 4 of the roller 1, so that the ground resistance (ground resistance of the ground electrode 21) for the compacted area portion (two-dimensional) with which the rear wheel 4 comes into contact can be measured. Then, the roller 1 moves over the entire compacted area, so that the ground resistance of the entire compacted area can be measured. Furthermore, by identifying locations where the measured values ​​of the ground resistance are relatively different, construction defects can be detected. Therefore, construction defects can be efficiently detected over a wide area of ​​the layer L to be compacted. 1, voltage electrode 22 and current electrode 23 serving as auxiliary electrodes are disposed outside the compaction area. This allows the distance between ground electrode 21 and the auxiliary electrodes to be sufficiently large, so that noise contained in the measured value of the ground resistance (the ground resistance of ground electrode 21) can be made extremely small, and the detection accuracy of defective parts can be significantly improved.

[0019] [Second embodiment] In describing the second embodiment, explanations of points that overlap with the first embodiment may be omitted. In addition, points of the second embodiment that overlap with the first embodiment may be selectively applied to the first embodiment.

[0020] <Configuration> FIG. 2 is an explanatory diagram of a construction quality control device of a second embodiment, where (a) is a plan view and (b) is a side view. The construction quality control device 100B (100) is a device that detects construction defects of a compaction target layer L in order to control the construction quality in compaction construction, similar to the construction quality control device 100A. The construction quality control device 100B includes the compactor 1 and the earth resistance meter 5 already described. The earth resistance meter 5 is an instrument that measures the electrical resistance between a grounded conductor and a ground surface, similar to the earth resistance meter 2. The earth resistance meter 5 includes ground electrodes 51A to 51D (51), an auxiliary electrode 52, and a main body 53. The ground electrode 51 is the same as the ground electrode 21. The main body 53 is the same as the main body 24. The auxiliary electrode 52 is an electrode that has both the function of the voltage electrode 22 and the function of the current electrode 23. The auxiliary electrode 52 is disposed at a position different from that of the ground electrode 51. The main body 53 is electrically connected to the ground electrode 51 and the auxiliary electrode 52. As shown in Fig. 2, the auxiliary electrode 52 is the front wheel 3, and can be grounded to the target layer L. Therefore, the ground resistance meter 5 can measure the ground resistance of the ground electrode 51 by the fall-of-potential method.

[0021] FIG. 3 is a configuration diagram of a ground electrode of the second embodiment. The ground electrode 51 can be implemented as rear wheels 4a to 4d (4) in which metal rings 41a to 41d (41) are fitted onto the tires 42a to 42d (42). The metal rings 41 make the rear wheels 4 conductive. The rolling mill 1 includes a frame 11, a shaft 12, and a drive unit 13 for the rear wheels 4. The frame 11 is the outer frame of the rear wheels 4. The shaft 12 is the rotation shaft of the rear wheels 4. The drive unit 13 is a drive source that rotates the shaft 12 around its axis. The ground electrode 51 includes slip rings 43a to 43d (43). The slip rings 43 are annular bodies arranged concentrically with the wheels 44a to 44d (44) of the rear wheels 4, and are a transmission mechanism for power and signals. Wirings 45a to 45d (45) are connected to the slip rings 43a to 43d. The main body 53 is electrically connected to the metal rings 41a to 41d via the slip rings 43a to 43d by wires 45a to 45d (45). The main body 53 is electrically connected to the auxiliary electrode 52 by a wire .

[0022] FIG. 4 is a configuration diagram of another example of the ground electrode of the second embodiment. In the example of FIG. 4, the metal rings 41a-41d and tires 42a-42d of the rear wheel 4 are replaced with iron wheels 46a-46d (46). Therefore, the rear wheel 4 in the example of FIG. 4 is conductive. At least in the measurement of the ground resistance of the ground electrode 51, the example of FIG. 3 and the example of FIG. 4 are the same. In addition, the rolling machine 1 is provided with bearings 18a-18d for the rear wheels 4a-4d. The bearings 18a-18d are insulators that rotate the iron wheel 46 around the axis of the shaft 12. Hereinafter, the second embodiment will be described using the example of FIG. 3.

[0023] FIG. 5 is a configuration diagram of the auxiliary electrode of the second embodiment. The auxiliary electrode 52 can be implemented as the front wheel 3 made of an iron wheel. Therefore, the front wheel 3 is conductive. The rolling machine 1 includes a frame 14, a shaft 15, bearings 16, 16, and a vibration mechanism 17 for the front wheel 3. The frame 14 is the outer frame of the front wheel 3. The shaft 15 is the rotation axis of the front wheel 3. The bearings 16, 16 are insulators that rotate the iron wheel around the axis of the shaft 15. The vibration mechanism 17 is a mechanism for performing vibration rolling with the front wheel 3. The auxiliary electrode 52 includes a slip ring 55. The slip ring 55 has the same function as the slip ring 43. A wiring 54 is connected to the slip ring 55. The main body 53 is electrically connected to the front wheel 3 via the slip ring 55 by the wiring 54.

[0024] <Equation for calculating earth resistance> According to Tagg's formula, when a cylindrical earth electrode is connected to a plate-like ground on the side of the cylinder, the earth resistance R of the earth electrode can be calculated using the following formula 1. R = (ρ / 4) (π / (a b)) 1 / 2 ...Formula 1 Here, ρ is the earth resistivity (Ωm), a is the vertical length of the earth electrode (m), and b is the horizontal length of the earth electrode (m). a is equal to the axial length of the cylinder. b is equal to the side ground length in the circumferential direction of the cylinder.

[0025] <On-site measurements> As shown in Fig. 2, when an AC voltage V [V] is applied from the ground electrode 51 by the fall of potential method and a current I [A] flows, the ground resistance R = V / I [Ω] is obtained. The ground resistance can be measured for each of the ground electrodes 51A to 51D, and R A ,R B ,R C ,R D Then, it can be calculated as shown in Equation 2 below. R A = V A / I A = R1+R 2A R B = V B / I B = R1+R 2B R C = V C / I C = R1+R 2C R D = V D / I D = R1+R 2D ...Formula 2 Here, V A ~V D : AC voltage applied to the ground electrodes 51A to 51D, I A ~I D : current flowing through the ground electrodes 51A to 51D, R1: ground resistance of the auxiliary electrode 52, R 2A ~R 2D : The ground resistance of the ground electrodes 51A to 51D. If the combined ground resistance for the four ground electrodes 51A to 51D is R2, then according to formula 3, R2 = 1 / R 2A + 1 / R 2B +1 / R 2C +1 / R 2D ...Formula 3 In addition, if the combined ground resistance of the four ground electrodes 51A to 51D and the auxiliary electrode 52 is R, then according to formula 4, R = R1 + R2 ...Formula 4 holds true.

[0026] Using equation 1, the ground resistance R1 of the auxiliary electrode 52 can be calculated by the following equation 5. R1 = (ρ1 / 4) (π / (a1 b1)) 1 / 2 ...Formula 5 Here, ρ1 is the resistivity of the ground near the electrode (layer L to be compacted). a1 is the width (axle length) of the front wheel 3, which is approximately 1.2 m. b1 is the side contact length of the front wheel 3, which is approximately 0.1 m. Thus, the ground resistance R1 of the auxiliary electrode 52 changes with the change in resistivity of the surface contact portion of the layer L to be compacted with the auxiliary electrode 52 as the compactor 1 travels, and with the ground contact conditions (ground contact area).

[0027] In addition, by using Equation 1, the ground resistance R of the ground electrode 51A is 2A can be calculated using the following Equation 6. R 2A = (ρ2 / 4)·(π / (a 2A b 2A )) 1 / 2 ...Formula 6 Here, ρ2 is the resistivity of the ground near the electrode (the layer L to be compacted). 2A is the width (axle length) of the rear wheel 4a, which is approximately 0.25 m. 2A is the side contact length of the rear wheel 4a, which is about 0.1 m. Therefore, the ground resistance R of the ground electrode 51A is 2A varies with the change in resistivity of the surface contact portion of the ground electrode 51A in the layer L to be compacted and with the ground contact condition (ground contact area) as the compactor 1 travels. The above description of the ground electrode 51A also applies to the ground electrodes 51B to 51D, and therefore will not be repeated.

[0028] <Detection of construction defects> The rolling machine 1 travels on the layer L to be compacted along a predetermined travel path to perform compaction. The method for detecting construction defects using the construction quality control device 100B includes a first step of measuring the ground resistance of the ground electrode 51 and a second step of detecting construction defects. The first and second steps continue during travel and are performed at various locations in the compacted area. By monitoring the change in the measured ground resistance of the ground electrode 51 over the entire compacted area, it is possible to detect defective locations. More specifically, first, the ground resistance meter 5 measures the voltage V relative to the current I flowing in the ground at the original position of the compacted area. From the measured current I and voltage V, the ground resistance meter 5 can calculate the combined ground resistance R for the four electrodes of the ground electrodes 51A to 51D and the auxiliary electrode 52. Furthermore, the ground resistance meter 5 calculates the ground resistance R of the ground electrodes 51A to 51D using Equations 2 to 6. 2A ~R 2D The earth resistance meter 5 can calculate the earth resistance R1 of the auxiliary electrode 52 and the combined earth resistance R2 for the four electrodes of the earth electrodes 51A to 51D. 2A ~R 2D ,By monitoring the changes in R1 and R2, the defective ,locations can be detected.

[0029] In addition, in consideration of the distance between the rear wheel 4, which is the ground electrode 51, and the front wheel 3, which is the auxiliary electrode 52, it is expected that the measured value of the ground resistance contains a considerable amount of noise. The ground resistance meter 5 can reduce the noise contained in the measured value to a desired level or less by performing a predetermined calculation process. For example, the predetermined calculation process may use a moving average. In this case, the change in the moving average of the change over time of the measured values ​​of the ground electrode 51 and the auxiliary electrode 52 is confirmed. The time difference Δt used for the moving average may be fixed, or may be appropriately set each time in consideration of the situation at the site. It may also be set in consideration of the moving speed of the roller 1. In addition,. Another example of the predetermined calculation process is one that uses the difference in the measured values ​​between each electrode. In this case, the difference in the measured values ​​is calculated for each combination of the ground electrodes (51A, 51B), (51A, 51C), (51A, 51D), (51B, 51C), (51B, 51D), and (51C, 51D), and the change in the difference is confirmed. A difference using the measurement value of the auxiliary electrode 52 may also be used.

[0030] <Example> Fig. 6 is an explanatory diagram (1 / 2) of construction defect detection in the second embodiment. Fig. 7 is an explanatory diagram (2 / 2) of construction defect detection in the second embodiment. Figs. 6(a), (b) and Figs. 7(a), (b) are plan views of the layer L to be compacted on which the compactor 1 runs. As shown in Fig. 6(a), when the compactor 1 runs over a sound portion of the layer L to be compacted, the earth resistance R measured at each of the earth electrodes 51A to 51D is A ,R B ,R C ,R D is R A = R1+R 2A , R B = R1+R 2B , R C = R1+R 2C , R D = R1+R 2D As shown in Equation 2, when the front wheel 3 of the rolling mill 1 travels and comes into contact with the defective portion S, the ground resistance R1 of the auxiliary electrode 52 changes due to a change in the resistivity or a change in the grounding condition (see Equation 5), as shown in FIG. A ,R B ,R C ,R D changes uniformly.

[0031] As shown in FIG. 7(a), when the rolling mill 1 continues to travel and the rear wheel 4b comes into contact with the defective portion S, the resistivity or the grounding condition changes, and the ground resistance R of the grounding electrode 51B decreases. 2B changes, and the earth resistance R of the earth electrodes 51A, 51C, and 51D 2A ,R 2C ,R 2D does not change. Therefore, the earth resistance R B Only the ground resistance R measured at each of the ground electrodes 51A to 51D changes. This makes it possible to determine that there is a defective part at the position where the rear wheel 4b passes in the width direction of the rolling compactor 1, and narrow down the location of the defective part. As shown in FIG. 7(b), when the rolling compactor 1 travels further and passes the defective part S, the rolling compactor 1 passes a sound part, which is the same as the case in FIG. 6(a). Therefore, the earth resistance R measured at each of the ground electrodes 51A to 51D changes. A ,R B ,R C ,RD is R A = R1+R 2A , R B = R1+R 2B , R C = R1+R 2C , R D = R1+R 2D and is as shown in Equation 2.

[0032] <Summary of the second embodiment> According to the second embodiment, the ground electrode 51 can be mounted on the rear wheel 4 of the roller 1, so that the ground resistance (ground resistance of the ground electrode 51) for the compacted area portion (two-dimensional) with which the rear wheel 4 comes into contact can be measured. Then, the roller 1 moves over the entire compacted area, so that the ground resistance of the entire compacted area can be measured. Furthermore, by identifying locations where the measured values ​​of the ground resistance are relatively different, construction defects can be detected. Therefore, construction defects can be efficiently detected over a wide range of the layer L to be compacted. 6 and 7, an auxiliary electrode 52 can be mounted on the front wheel 3 to measure the sum of the ground resistance of the ground electrode 51 and the ground resistance of the auxiliary electrode 52. These measurements are the same in that they monitor changes in the ground resistance to detect construction defects. In addition, since there are two or more rear wheels 4a-4d (4), it is possible to mount the ground electrodes 51A-51D (51) on each of the two or more rear wheels 4, and therefore it is possible to measure the ground resistance for each of the ground electrodes 51A-51D arranged (lined up) at different positions. Therefore, if a relatively different ground resistance is measured for any of the two or more ground electrodes 51A-51D, it can be determined that there is a construction defect at the location where the ground electrode 51A-51D comes into contact. In this way, since there are two or more rear wheels 4a-4d mounted with the ground electrodes 51A-51D, it is possible to narrow down the defective location. In addition, even if the rolling machine 1 is moving, the ground resistance can be measured while keeping the distance between the ground electrode 51 and the auxiliary electrode 52 constant. This makes it possible to reduce noise contained in the measured value and improve the accuracy of detecting defective parts.

[0033] <Another Example of the Second Embodiment> FIG. 8 is a configuration diagram of a second example of the auxiliary electrode of the second embodiment. Compared with the rolling machine 1 shown in FIG. 2, as shown in FIG. 8, the rolling machine 1 is provided with an auxiliary wheel 6 in front of the front wheel 3. The auxiliary wheel 6 can be, for example, an iron wheel and has electrical conductivity. The auxiliary electrode 52 is the auxiliary wheel 6 and can be grounded to the layer L to be rolled. Thus, the ground resistance meter 5 can measure the ground resistance of the ground electrode 51 by the fall-of-potential method. The configuration of the auxiliary electrode 52 mounted on the auxiliary wheel 6 can be, for example, similar to that shown in FIG. 5. According to the configuration in Fig. 8, the distance between the ground electrode 51 and the auxiliary electrode 52 can be made larger than when the auxiliary electrode 52 is the front wheel 3 (Fig. 2). In addition, even if the rolling machine 1 is moving, the ground resistance can be measured while keeping the distance between the ground electrode 51 and the auxiliary electrode 52 constant. This makes it possible to further reduce noise contained in the measured value and further improve the accuracy of detecting defective parts.

[0034] [Variations] (a): The ground electrode (21, 51) may be the front wheel 3 or the auxiliary wheel 6. The auxiliary electrode 52 may be the rear wheel 4. (b): In the first embodiment, the ground resistance measured by ground resistance meter 2 may be the sum of the ground resistance of ground electrode 21 and the ground resistance of current electrode 23. In other words, voltage electrode 22 does not need to be provided. By monitoring the changes in the sum of the ground resistance of ground electrode 21 and the ground resistance of current electrode 23 at various points in the compacted area, defective locations can be detected. (c): In the second embodiment, the ground resistance measured by the ground resistance meter 5 may be the ground resistance of the ground electrode 51. In other words, the ground resistance meter 5 measures the ground resistance R 2A ~R 2D By monitoring the change in temperature, it is possible to detect defective areas.

[0035] (d) It is also possible to realize a technology that appropriately combines the various technologies described in this embodiment. (e) The software described in this embodiment can be realized as hardware, and vice versa. (f) In addition, the hardware, software, flow charts, etc. may be modified as appropriate without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0036] 100A,100B,100 Construction quality control device 1. Roller 2,5 Earth resistance meter 3 Front wheel 4a~4d,4 Rear wheel 6. Training wheels 11,14 Frame 12,15 Shaft 13 Drive unit 16,18a~18d Bearings 17 Vibration mechanism 21,51,51A~51D Ground electrode 22 Voltage electrode 23 Current electrode 24,53 Main body 25, 26, 27 Wiring 41a~41d,41 Metal ring 42a~42d,42 Tires 43a~43d,43,55 Slip ring 44a~44d,44 Wheels 45a~45d,45,54 Wiring 46a~46d,46 Iron wheel 52 Auxiliary electrode L Compaction target layer S Defective part

Claims

1. A construction quality control device for controlling the construction quality in rolling construction, Equipped with a rolling machine and a ground resistance meter, The earth resistance meter includes an earth electrode and an auxiliary electrode, The ground electrode is a rear wheel or a front wheel of the rolling mill, A construction quality control device, wherein the rear wheels or the front wheels are conductive.

2. The construction quality control device according to claim 1 , wherein the ground electrode is the rear wheel, and the number of the rear wheels is two or more.

3. 3. The construction quality control device according to claim 2, wherein the ground electrode is the rear wheel, and the auxiliary electrode is the front wheel.

4. 3. The construction quality control device according to claim 2, wherein the grounding electrode is the rear wheel, and the auxiliary electrode is an auxiliary wheel of the rolling machine located forward of the front wheel.

5. The construction quality control device according to claim 1 or 2, wherein the auxiliary electrode is disposed outside a rolling area.

6. A construction defect detection method using the construction quality control device according to claim 1 or 2, A first step of measuring the ground resistance of the ground electrode; A second step of detecting a construction defect.

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