Quality Evaluation Method

Abstract

To provide a quality evaluation method enabling intensity of stone material which may deteriorate over time to be easily detected, and enabling such stone material to be reinforced if necessary.SOLUTION: There is provided a quality evaluation method comprising the steps of: acquiring stone material B as a sample, from a site; hitting a surface H of the stone material B by a hammer 1; measuring acceleration of the hammer 1 to the surface H and a hitting speed of the hammer 1; calculating intensity at the surface H from the hitting acceleration and the hitting speed; acquiring, relationship between a depth and intensity of the stone material B, by repeating, a step of calculating intensity while polishing the surface H; hitting the surface of the stone material B on the site by the hammer 1, thereby calculating intensity on the surface of the stone material B, and estimating intensity of a healthy portion of the stone material B on the site, from the relationship between the depth and intensity of the stone material B; and replacing at least a part of the stone materials B, if the estimated intensity is less than or equal to a prescribed threshold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a quality assessment method. [Background technology]

[0002] Patent Document 1 describes a method for managing dismantled stones. This method includes the steps of assigning unique identifiers to the dismantled stones, taking images of the dismantled stones, collecting attribute information about the dismantled stones, collecting technical information necessary for re-stacking each dismantled stone, and temporarily placing the dismantled stones and then using a GPS to determine their temporary placement positions. The GPS uses an RTK (real-time kinematic) positioning method. Furthermore, before and after the step of determining the temporary placement positions, steps are performed to measure the strength of the stones. This strength measurement is performed using a Schmidt-rock hammer, an impact analysis device, or an ultrasonic measurement device.

[0003] Patent Document 2 describes a method and system for inspecting concrete structures. This inspection system includes a hammer with a sphere, an acceleration sensor that detects the acceleration of the sphere, a cable extending from the acceleration sensor, and a monitor connected to the cable. The monitor is a computer that calculates the elastic modulus of the concrete structure. In this inspection method, the sphere of the hammer strikes a measurement site of the concrete structure, and the contact time between the sphere and the concrete structure and the velocity of the sphere are measured.

[0004] The elastic modulus of the concrete structure is then calculated from the contact time, velocity of the sphere, Poisson's ratio of the sphere, elastic modulus of the sphere, mass of the sphere, radius of the sphere, and Poisson's ratio of the concrete structure. The calculated elastic modulus of the concrete structure is compared with a preset soundness threshold. If the elastic modulus is smaller than the soundness threshold, the concrete structure is evaluated as having either lifting or spalling. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-65349 [Patent Document 2] Patent No. 6709713 Summary of the Invention [Problem to be solved by the invention]

[0006] However, since stone materials weather over time, it is necessary to measure their strength periodically and reinforce them as necessary. However, there are cases where a large amount of stone is present on-site, and in such cases it can be difficult to measure the strength of all the stone materials on-site. Therefore, there is a need to easily measure the strength of stone materials on-site and reinforce them as necessary.

[0007] The present disclosure aims to provide a quality evaluation method that can easily measure the strength of stone that may be subject to deterioration over time and reinforce the stone as necessary. [Means for solving the problem]

[0008] A quality assessment method according to one aspect of the present disclosure is a quality assessment method for stone that weathers over time. The quality assessment method includes the steps of acquiring a sample of stone from a site, striking the surface of the stone with a hammer, measuring the hammer's impact speed and the acceleration of the hammer relative to the surface when striking the surface with the hammer, calculating the strength of the surface from the impact speed and acceleration, obtaining a relationship between the depth and strength of the stone by repeating the step of calculating the strength while polishing the surface, striking the surface of the stone at the site with the hammer to calculate the strength of the surface of the stone at the site, and estimating the strength of a sound portion of the stone at the site from the relationship between the depth and strength of the stone, and replacing at least a portion of the stone if the estimated strength is equal to or less than a predetermined threshold.

[0009] In this quality assessment method, a stone sample possibly deteriorating over time is acquired from a site, and the surface of the acquired stone is struck with a hammer to measure the hammer impact speed and the hammer acceleration relative to the surface. The strength of the stone at its surface is calculated from the measured impact speed and acceleration. The stone's surface is then polished while repeatedly calculating the strength, thereby obtaining the relationship between the stone's depth and strength. Therefore, the relationship between the stone's depth and strength can be obtained from the stone sample acquired from the site, and the strength of the sound portion can be estimated. Furthermore, the surface of the stone at the site is struck with a hammer to calculate the strength at the surface, and the strength of the sound portion of the stone at the site is estimated from the relationship between the stone's depth and strength obtained from the sample stone. At the site, the strength of stone that has deteriorated over time is largely dependent on the strength of the sound portion that has not deteriorated over time. This quality assessment method allows the strength of the sound portion of the stone to be estimated by striking the surface at the site based on the previously acquired relationship between the stone's depth and strength, making it easy to estimate the strength of stone that may have deteriorated over time. Furthermore, if the estimated strength is below a predetermined threshold, a portion of the stone is replaced, so that the stone can be reinforced as needed if its strength is below the threshold.

[0010] Another aspect of the present disclosure relates to a quality assessment method for evaluating the quality of stone that weathers over time, and the quality assessment method includes the steps of obtaining a sample of stone from a site, striking the surface of the stone with a hammer, measuring the hammer's impact speed when striking the surface with the hammer and the acceleration of the hammer relative to the surface, calculating the strength of the surface from the impact speed and acceleration, and obtaining a relationship between the depth and strength of the stone by repeating the steps of calculating the strength while polishing the surface, striking the surface of the stone at the site with the hammer to calculate the strength of the stone at the site and estimating the depth of a sound portion of the stone at the site from the relationship between the depth and strength of the stone, and installing an anchor foundation in the stone at the site so as to extend to a position deeper than the depth of the sound portion.

[0011] In this quality assessment method, similar to the aforementioned quality assessment method, stone samples that may be subject to deterioration over time are acquired from the site, and the relationship between the stone's depth and strength is acquired by repeatedly calculating the strength while polishing the surface of the acquired stone. Therefore, the relationship between the stone's depth and strength can be acquired from the stone sample acquired from the site. The surface of the stone at the site is also struck with a hammer to calculate the strength at that surface, and the depth of the sound part of the stone at the site is estimated from the relationship between the stone's depth and strength acquired from the sample stone. Furthermore, anchor foundations are installed in the stone at the site so that they extend deeper than the depth of the sound part. Therefore, anchor foundations can be installed to an appropriate depth using the estimated sound part, allowing the stone to be reinforced as needed.

[0012] The quality evaluation method may further include a step of estimating the timing for repair of the on-site stone from the relationship between the depth and strength of the stone. In this case, the timing for repair of the on-site stone can be estimated from the relationship between the depth and strength previously obtained from the sample stone, so that the deterioration of the stone over time can be predicted and the stone can be reinforced at an appropriate time. [Effects of the Invention]

[0013] According to the present disclosure, the strength of stone materials that may be subject to deterioration over time can be easily measured, and the stone materials can be reinforced as necessary. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a side view showing an example of a stone to which a quality evaluation method according to an embodiment is applied. [Figure 2] FIG. 10 is a diagram showing a process of striking the surface of a stone with a hammer. [Figure 3] 1 is a flowchart illustrating an example of steps of a quality evaluation method according to an embodiment. [Figure 4] 1 is a graph showing an example of the relationship between depth and strength (elastic modulus) of stone. [Figure 5] Graphs (a) and (b) show examples of the relationship between depth and strength (elastic modulus) of stone. [Figure 6] 1 is a graph showing an example of the relationship between depth and strength (elastic modulus) of stone. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the quality evaluation method according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations will be omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated to facilitate understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0016] FIG. 1 is a diagram showing an exemplary site A to which the quality assessment method according to this embodiment is applied. As shown in FIG. 1, a structure S is constructed on a stone B. That is, the stone B is used as the foundation of the structure S. As an example, a plurality of stones B are lined up along both a vertical direction D1 and a horizontal direction D2. For example, the plurality of stones B include a first stone B1 and a second stone B2 that are provided on the ground, and a third stone B3 that is at least partially buried underground.

[0017] At site A, the soundness of multiple stones B is evaluated. Stones B are existing stones that make up structure S, and are stones that have weathered over time and may have cross-sectional defects or reduced strength. If the evaluation determines that stone B needs repair, then at least one of reinforcement and replacement of stone B will be carried out.

[0018] Non-destructive testing, including visual inspection and hammering testing, is known as a method for assessing the deterioration of structures. However, these methods are primarily aimed at the surface layer of stone B, making it difficult to accurately assess stone B that has deteriorated at site A. Since the deterioration (weathering) of stone B progresses from the surface of stone B toward the interior of stone B, it is not easy to accurately assess stone B at site A using the above methods. When a large number of stone B exist at site A, it is necessary to be able to assess stone B accurately and efficiently.

[0019] As shown in Fig. 2, in this embodiment, a ball-hitting inspection method is used to evaluate stone B. The ball-hitting inspection method uses a hammer 1 having a spherical hitting part 3 attached to the tip of a handle 4, and an accelerometer 2 attached to the hitting part 3. The hammer 1 is used to hit stone B, which is the object of quality evaluation.

[0020] The accelerometer 2 measures the acceleration in the direction of collision between the striking part 3 and the stone B. When the stone B is struck by the hammer 1, the accelerometer 2 detects the impact waveform generated by the collision between the striking part 3 and the stone B as an acceleration waveform (acceleration data). The striking part 3 is made of metal, for example, and has a diameter of 50 mm.

[0021] In the impact ball detection method, the elastic modulus can be quickly and easily determined using Hertz's theoretical formula from the acceleration waveform obtained from the accelerometer 2 when the striking part 3 of the hammer 1 strikes stone B. By using this theory, the elastic modulus can be calculated regardless of the strength of the strike (the amount of energy at the time of the strike).

[0022] In the quality evaluation method for stone B according to this embodiment, a sampling test is conducted on stone B in advance, and the stone B at site A is evaluated using the results of the sampling test. In the sampling test for stone B, stone B is obtained as a sample stone from stone B under the same conditions as site A (under the same environment, such as the same weather conditions). Then, a ball inspection method is used to determine the relationship between the strength and depth (distance from the surface) of stone B from the sample stone B, and the stone B at site A is evaluated using this relationship. Below, a specific example of the quality evaluation method for stone B according to this embodiment is described.

[0023] Fig. 3 is a flowchart showing an example of steps in a quality evaluation method for stone B according to this embodiment. As shown in Fig. 3, first, stone B is acquired as a sample stone from a site A (a step of acquiring a stone, step S1). At this time, stone B is moved from the site A into a testing room, and then a laboratory test is performed on stone B.

[0024] In the indoor test of stone B, a hammer 1 is prepared to strike stone B (hammer preparation process). For example, as shown in Figure 2, a hammer 1 is prepared with a striking part 3 attached to the tip of a handle 4, and an accelerometer 2 is attached to the surface of the striking part 3. For example, a cable 5 extends from the accelerometer 2, and a charge amplifier 6, a terminal panel 7, an AD converter 8, and a computer (arithmetic unit) 9 are connected to the cable 5.

[0025] Next, the surface of stone B is struck with hammer 1 (step of striking the surface of stone, step S2). For example, striking unit 3 is struck perpendicularly to surface H of stone B. When surface H of stone B is struck with striking unit 3, accelerometer 2 detects an acceleration waveform. The acceleration waveform detected by accelerometer 2 is transmitted to computer 9 as, for example, an acceleration signal via cable 5, charge amplifier 6, terminal panel 7, and AD converter 8. Charge amplifier 6 amplifies the acceleration signal from accelerometer 2, and terminal panel 7 removes noise components contained in the amplified signal. AD converter 8 performs AD conversion of the noise-removed signal. Computer 9 performs calculations based on the acceleration signal obtained from accelerometer 2 and outputs an evaluation result for stone B.

[0026] Next, the impact speed of the hammer 1 and the acceleration of the hammer 1 relative to the surface H of the stone B are calculated (a process of measuring the impact speed of the hammer and the acceleration of the hammer relative to the surface). For example, the computer 9 calculates the impact speed of the hammer 1 (the speed of the striking part 3) by integrating the acceleration of the striking part 3 of the hammer 1 detected by the accelerometer 2 until the striking part 3 of the hammer 1 comes into contact with the stone B. Then, the computer 9 analyzes the acceleration signal obtained from the accelerometer 2 to measure the acceleration of the striking part 3 of the hammer 1 and the stone B.

[0027] Next, the strength of the surface H of stone B is calculated from the impact speed and acceleration (strength calculation process, step S3). In this embodiment, the computer 9 calculates the elastic modulus of stone B as the strength of stone B. The computer 9 calculates the elastic modulus of stone B from the above impact speed and acceleration, the Poisson's ratio of the impact part 3, the elastic modulus of the impact part 3, the mass of the impact part 3, the radius of the impact part 3, and the Poisson's ratio of stone B.

[0028] In this embodiment, Hertz's elastic contact theory is used to calculate the elastic modulus of the surface H of the stone B as the strength of the surface H. According to Hertz's elastic contact theory, the elastic modulus Ec of the surface H of the stone B can be calculated using the formula (1) described below.

number

[0029] After calculating the strength (elastic modulus) of the surface H of the stone B as described above, the surface H is polished using a core end surface polishing machine (a process of polishing the surface of the stone, step S4). The core end surface polishing machine is, for example, a grinder. After polishing the surface H, the strength of the surface H is calculated by striking the surface H with the striking part 3 of the hammer 1, as described above.

[0030] As mentioned above, weathering of stone B progresses from the surface H of stone B toward the interior of stone B, so if the calculation of the strength of surface H is repeated while polishing surface H of stone B, the strength gradually increases. The calculation of the strength of surface H is repeated while polishing surface H, and the depth of stone B (depth from surface H) when the strength becomes constant is the depth of the sound part (unweathered part) of stone B. Therefore, the calculation of the strength of surface H is repeated while polishing surface H, and after the calculated strength becomes constant (YES in step S5), the relationship between the strength and depth of stone B is obtained (relationship obtaining process, step S6).

[0031] The relationship between the strength and depth of stone B is shown in the graph in Figure 4. Figure 4 shows the relationship between the depth from the surface H of stone B and the elastic modulus (GN / m 2 ) for the first stone B1, the second stone B2, and the third stone B3 (for the third stone B3, the upper part and the lower part of the third stone B3).

[0032] As shown in FIG. 4, the elastic modulus of each of the first stone B1, the second stone B2, and the third stone B3 increases the further away (the deeper) they are from the surface H. This shows that the quality assessment method according to this embodiment can quantitatively evaluate the degree of weathering of the stone B. Furthermore, the elastic modulus near the surface H of the third stone B3, which is partially buried underground, is smaller than the elastic modulus near the surface H of the first stone B1 and the second stone B2, which are above ground. In other words, the third stone B3, which is partially buried underground, has a greater degree of weathering at its surface H than the first stone B1 and the second stone B2. The trend in the elastic modulus of the upper part of the third stone B3 is similar to the trend in the elastic modulus of the lower part of the third stone B3.

[0033] As described above, the soundness trends of the first stone B1 and the second stone B2 are consistent, and the soundness trends of the upper part of the third stone B3 and the lower part of the third stone B3 are consistent. Furthermore, for the first stone B1, the second stone B2, and the third stone B3, once the depth from the surface H reaches a certain level, the increase in the modulus of elasticity slows down and the modulus of elasticity stabilizes. In the example of Figure 4, the modulus of elasticity stabilizes when the depth from the surface H is 30 mm or more, indicating that the depth of the sound part of stone B is approximately 30 mm.

[0034] Figure 5(a) is a graph obtained by extracting the relationship between depth and elastic modulus for the first stone B1 and the second stone B2 from the graph in Figure 4. Figure 5(b) is a graph obtained by extracting the relationship between depth and elastic modulus for the upper part of the third stone B3 and the lower part of the third stone B3 from the graph in Figure 4. In Figures 5(a) and 5(b), the elastic modulus at depths of 30 mm or more is normalized to 1.

[0035] As shown by the dashed line in Figure 5(a), if the depth is x and the elastic modulus is y, then from the first stone B1 and the second stone B2, y=0.0116x+0.6508(0≦x≦30) y=1(30≦x) The relationship between depth and strength (elastic modulus) was obtained. Also, as shown by the dashed line in Figure 5(b), from the top of the third stone B3 and the bottom of the third stone B3, y=0.029x+0.1288(0≦x≦30) y=1(30≦x) The relationship between depth and intensity was obtained.

[0036] As described above, after obtaining the relationship between depth and strength from the sample stone, the strength of the sound part of stone B at site A is estimated, for example (step of estimating the strength of the sound part of stone at site, step S7). Specifically, as described above, the hammer 1 strikes the surface of stone B at site A, and computer 9 measures the striking speed and acceleration of hammer 1 and calculates the strength (elastic modulus) of surface H of stone B at site A. Then, the strength of the sound part of stone B at site A is estimated from the relationship between depth and strength described above.

[0037] For example, for stone B at site A in the same environment as the first stone B1 or the second stone B2, the strength of the sound part is estimated from the relationship between depth and strength shown in Figure 5(a). In this case, the strength of the sound part of stone B is estimated assuming that the depth of the sound part of stone B is constant (for example, 30 mm) in the same environment as the first stone B1 or the second stone B2. For example, since the intercept of the graph in Figure 5(a) is 0.6508, the elastic modulus E at the surface H of stone B at site A is s Therefore, the elastic modulus E0 of the sound part of the stone B can be estimated using the following equation (2). E0=E s / 0.6508 (2)

[0038] On the other hand, for the stone at site A under the same environment as the third stone B3, the strength of the sound part is estimated from the relationship between depth and strength shown in Figure 5(b). For example, since the intercept of the graph in Figure 5(b) is 0.1288, the elastic modulus E at the surface H of stone B at site A is s Therefore, the elastic modulus E0 of the sound part of the stone B can be estimated using the following equation (3). E0=E s / 0.1288 (3) As described above, in this embodiment, by testing multiple different types of sample stone, it is possible to grasp the strength trends of multiple types of stone.

[0039] Furthermore, after obtaining the relationship between depth and strength from the sample stone, the depth of the sound part of stone B at site A may be estimated (step of estimating the depth of the sound part of stone B at site, step S7). Specifically, as described above, after calculating the strength of surface H of stone B at site A, the depth of the sound part of stone B at site A is estimated from the relationship between depth and strength described above.

[0040] For example, for stone B at site A in the same environment as the first stone B1 or the second stone B2, the depth of the sound part is estimated from the relationship between depth and strength shown in Figure 5(a). For example, the normalized elastic modulus E at the surface H of stone B at site A is calculated using the equation in Figure 5(a) s Using this, the depth X0 of the sound part of the stone B can be estimated from the following equation (4). 1=0.0116X0+E s ···(4)

[0041] In addition, for Stone B at Site A, which is in the same environment as Stone B3, the depth of the sound part is estimated from the relationship between depth and strength shown in Figure 5(b). Specifically, the normalized elastic modulus E at the surface H of Stone B at Site A is calculated using the equation in Figure 5(b) and s Using this, the depth X0 of the sound part of the stone B can be estimated from the following equation (5). 1=0.029X0+E s ···(5)

[0042] As described above, after estimating the strength or depth of the sound portion of stone B at site A, it is determined whether or not repair of stone B at site A is necessary (step S8). At this time, for example, it is determined whether the strength of the sound portion of stone B at site A is equal to or greater than a predetermined threshold. If it is determined that repair is not necessary (NO in step S8), the series of steps is completed. On the other hand, if it is determined that repair is necessary (YES in step S8), for example, an anchor foundation is installed in stone B at site A (anchor foundation installation step, step S9). The anchor foundation installation step is performed, for example, based on the depth of the sound portion of stone B at site A estimated in step S7. At this time, the anchor foundation is installed so that its embedded depth is equal to or greater than the depth of the sound portion. For example, if the depth of the sound portion is 30 mm, the embedded depth of the installed anchor foundation will be 30 mm or greater.

[0043] Furthermore, if it is determined that repair is necessary (YES in step S8), at least a portion of stone B at site A may be replaced (step of replacing at least a portion of stone, step S9). The step of replacing at least a portion of stone is carried out, for example, based on the strength of the sound portion of stone B at site A estimated in step S7. At this time, for example, weathered stone B is replaced with a new stone B. Furthermore, the replacement step may be carried out based on the depth of the sound portion of stone B at site A estimated in step S7.

[0044] After step S9 is executed as described above, the series of steps is completed. Note that instead of installing an anchor foundation or replacing stone B in step S9, stone B may be repaired by a method other than these. In this way, when it is determined in step S8 that repair is necessary, the repair method and repair means for stone B can be changed as appropriate.

[0045] Next, the effects obtained from the quality evaluation method according to this embodiment will be described. As described above, in this quality evaluation method, a stone B that may be subject to deterioration over time is acquired as a sample from a site A, and the surface H of the acquired stone B is struck with a hammer 1 to measure the impact speed of the hammer 1 and the acceleration of the hammer 1 relative to the surface H. The strength of the surface H of the stone B is calculated from the measured impact speed and acceleration. Then, by repeating the above strength calculation while polishing the surface H of the stone B, the relationship between the depth and strength of the stone B is obtained. Therefore, the relationship between the depth and strength of the stone B can be obtained from the stone B acquired as a sample from the site A.

[0046] Furthermore, the surface H of stone B at site A is struck with hammer 1 to calculate the strength at surface H, and the strength of the sound part of stone B at site A is estimated from the relationship between the depth and strength of stone B obtained from the sample stone B. Therefore, at site A, the strength of the sound part of stone B can be estimated by striking surface H from the relationship between the depth and strength of stone B obtained in advance, so that the strength of stone B that may be subject to deterioration over time can be easily estimated.

[0047] Furthermore, if the estimated strength is equal to or less than a predetermined threshold, part of stone B is replaced. Therefore, if the strength of stone B is equal to or less than the threshold, stone B can be reinforced as needed. Also, if the estimated strength is equal to or less than a predetermined threshold, anchor foundations may be installed on stone B at site A so that they extend to a position deeper than the depth of the sound part. In this case, anchor foundations can be installed to an appropriate depth using the estimated depth of the sound part, making it possible to reinforce stone B as needed.

[0048] The above describes an embodiment of the stone quality evaluation method according to the present disclosure. However, the quality evaluation method according to the present disclosure is not limited to the above-described embodiment and can be modified as appropriate within the scope of the gist described in the claims. In other words, the content and order of the steps of the quality evaluation method are not limited to the above-described embodiment and can be modified as appropriate.

[0049] For example, the quality evaluation method may estimate the time when stone B at site A needs repair based on the relationship between depth and strength for stone B, a sample stone shown in Figure 4, Figure 5(a), or Figure 5(b) (the step of estimating the time when repair is required). For example, the equation of the graph shown in Figure 6 is y = 0.0116x + 0.6508, but the intercept value of 0.6508 decreases over time, and the slope of the graph changes to L1 and L2. As an example, L1 indicates a certain number of years later, and L2 indicates another certain number of years later. In the step of estimating the time when repair is required, the relationship between depth and strength after a certain number of years is calculated, and the stone may be repaired when the depth of the sound portion exceeds a certain value or the strength of the surface H of stone B falls below a certain value. As a specific example, repair may be performed after a certain number of years when the relationship between depth and strength reaches L1, or after another certain number of years when the relationship reaches L2.

[0050] In this case, it becomes possible to carry out necessary repairs at the necessary time for stone B at site A. In other words, since the time for repairs of stone B at site A can be estimated from the relationship between depth and strength obtained in advance from the sample stone B, it is possible to predict the deterioration of stone B over time and reinforce stone B at the appropriate time.

[0051] In the above embodiment, an example has been described in which the accelerometer 2 is connected to the cable 5, the charge amplifier 6, the terminal panel 7, the AD converter 8, and the computer 9. However, the signal processing device for the acceleration waveform obtained when the stone B is struck with the hammer 1 is not limited to the above example and can be modified as appropriate.

[0052] In the above-described embodiment, an example has been described in which a structure S is constructed on top of stone B, and stone B is used as the foundation of structure S. However, the stones that are the subject of the quality evaluation method according to the present disclosure are not limited to those on which a structure is constructed, and can be changed as appropriate. In this way, the quality evaluation method according to the present disclosure can be used for various stone materials as long as they are stone materials that weather over time. [Explanation of symbols]

[0053] 1...Hammer, 2...Accelerometer, 3...Striking part, 4...Handle, 5...Cable, 6...Charge amplifier, 7...Terminal panel, 8...AD converter, 9...Computer, A...Site, B...Stone, B1...First stone, B2...Second stone, B3...Third stone, D1...Vertical direction, D2...Horizontal direction, H...Surface, S...Structure.

Claims

1. A method for evaluating the quality of stone that weathers over time, comprising: The stone is used as a foundation for a structure, obtaining stone samples from the site; striking the surface of the stone with a hammer; measuring the impact velocity of the hammer when the hammer strikes the surface and the acceleration of the hammer relative to the surface; calculating a strength at the surface from the impact velocity and the acceleration; a step of obtaining a relationship between the depth and the strength of the stone by repeating the step of calculating the strength while polishing the surface; a step of calculating the strength of the surface of the stone at the site by hitting the surface of the stone at the site with a hammer, and estimating the strength of the sound part of the stone at the site from the relationship between the depth and the strength of the stone; replacing at least a portion of the stone if the estimated strength is less than or equal to a predetermined threshold; A quality evaluation method comprising:

2. A method for evaluating the quality of stone that weathers over time, comprising: The stone is used as a foundation for a structure, obtaining stone samples from the site; striking the surface of the stone with a hammer; measuring the impact velocity of the hammer when the hammer strikes the surface and the acceleration of the hammer relative to the surface; calculating a strength at the surface from the impact velocity and the acceleration; a step of obtaining a relationship between the depth and the strength of the stone by repeating the step of calculating the strength while polishing the surface; a step of calculating the strength of the surface of the stone at the site by hitting the surface of the stone at the site with a hammer, and estimating the depth of the sound part of the stone at the site from the relationship between the depth and the strength of the stone; installing anchor foundations in the on-site masonry so as to extend to a depth greater than the depth of the sound section; A quality evaluation method comprising:

3. The method further comprises a step of estimating the time when the stone at the site needs to be repaired based on the relationship between the depth and strength of the stone. The quality evaluation method according to claim 1 or 2.

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