JP2013015412A - Physical property evaluation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physical property evaluation apparatus which is capable of easily evaluating the physical property of a target on the basis of the Hertzian theory of elastic contact even if the worker's hand is unlikely to reach an impact point.SOLUTION: A physical property evaluation apparatus 1 comprises a rod body 3 for a worker to hold the rear end side thereof, a metallic hammer 13 which is connected to a front end part of the rod body 3 and includes an acceleration sensor 15 and a spherical impact surface 13a, and a computer which arithmetically operates the deformation property of a target on the basis of acceleration data obtained by the acceleration sensor 15 when an impact surface 13a of the hammer 13 collides with the target (rock-bed 53). The hammer 13 is supported to be movable in a direction of the collision between the impact surface 13a and the target, with respect to the rod body 13.

Description

  The present invention relates to a physical property evaluation apparatus for evaluating physical properties of an object.

  Conventionally, as a technology in such a field, a nondestructive measuring apparatus described in Patent Document 1 below is known. This device consists of a ball-shaped hammer that strikes the surface of a concrete structure, a sensor for collecting the impact signal when the hammer strikes, and the Hertz elastic contact from the impact signal collected by the sensor. And a control device for deriving the rigidity of the concrete structure based on the theory. As another technique in this field, a Schmitt hammer test method is known in which concrete is hit using a dedicated device to estimate the strength of the concrete.

JP 2004-150946 A

  In the apparatus of Patent Document 1, it is necessary for an operator to grip a hammer handle and hit a point to be hit on the surface of the object (hereinafter, “hit point”). For example, when it is desired to evaluate the characteristics of a rock in the face of a tunnel under construction, it is necessary to hit the rock. However, since there is a risk of falling rocks and skin falling near the face, workers should avoid approaching the face from the viewpoint of preventing occupational accidents. Therefore, the striking point is at a position that cannot be reached by the operator, and it is difficult to use the method of Patent Document 1. Further, for example, when it is desired to evaluate the characteristics of the side wall of the tunnel, it may be necessary to hit a high position on the side wall of the tunnel. In this case, if the worker's hand does not reach the hitting point, it is necessary to assemble a scaffold in the tunnel, which takes time and effort. In addition, the Schmitt hammer test method cannot be applied if the worker's hand does not reach the strike point.

  Therefore, the present invention has an object to provide a physical property evaluation apparatus that can easily perform physical property evaluation of an object based on Hertz's elastic contact theory even when it is difficult for an operator to reach a hitting point. .

  A physical property evaluation apparatus according to the present invention is a physical property evaluation device for evaluating physical properties of an object, and is connected to a rod body for an operator to hold the rear end side, a front end portion of the rod body, an acceleration sensor, and a spherical surface. A hammer having a striking surface having a shape, and acceleration data acquisition means for acquiring acceleration data for calculating deformation characteristics of the object from the acceleration sensor when the striking surface of the hammer collides with the object. The hammer is supported so as to be movable in the collision direction between the striking surface and the object with respect to the rod.

  According to the physical property evaluation apparatus of the present invention, even when the operator's hand is difficult to reach the hit point, the operator brings the front end of the bar close to the hit point while holding the rear end side of the bar, A hammer connected to the front end of the body can collide with the strike point. Then, acceleration data at the time of collision is obtained by the acceleration sensor. In the subsequent steps, the deformation characteristics of the object are calculated based on Hertz's elastic contact theory based on the obtained acceleration data. Here, in order to obtain appropriate acceleration data applicable to Hertz's elastic contact theory, it is necessary to cause the hammer and the object to collide in a state where the movement of the hammer due to repulsion is allowed at the moment of collision. According to the physical property evaluation apparatus of the present invention, the hammer is supported so as to be movable in the collision direction between the striking surface and the target object with respect to the rod body. It is in a state in which the movement of the hammer due to repulsion is allowed, and appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained.

  Further, the acceleration data acquisition means may include a calculation means for calculating the deformation characteristics of the object based on the acquired acceleration data. The acceleration data acquisition means may be an electronic storage medium that stores the acquired acceleration data as electronic data.

  Specifically, the connecting portion between the rod body and the hammer urges the hammer forward with a movement allowing portion that enables the hammer to move parallel to the rod body in the extending direction of the rod body. It is good also as a structure which has a biasing part.

  In this configuration, the worker collides the hammer connected to the front end of the rod with the hit point by holding the rear end of the rod and pushing the hit point of the object on the front end of the rod. Can be made. Since the hammer is connected to the rod body by the movement allowing portion so as to be movable in the extending direction of the rod body, the hammer collides with the object in a state in which the movement of the hammer due to repulsion is allowed. . Accordingly, appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained.

  Further, since the rod body is quickly accelerated forward during the piercing operation, the hammer tends to move backward with respect to the rod body due to inertia. At this time, if the hammer reaches the rear end limit of the movement allowable range of the movement allowable portion, the movement of the hammer at the moment of collision is limited, and appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained. You can't get it. Therefore, by providing the urging portion, it is possible to urge the hammer forward when the rod body is accelerated, and to prevent the hammer from reaching the rear end limit of the allowable movement range. Therefore, even when the rod is rapidly accelerated, appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained.

  Further, specifically, the connecting portion between the rod body and the hammer is provided with a hammer at one end, and the other end is rotatable with respect to the rod body in a plane parallel to the extending direction of the rod body. It is good also as a structure which has the rod-shaped member currently supported.

  In this configuration, the operator can hold the rear end side of the rod body, rotate the rod-shaped member to swing the hammer, and cause the hammer to collide with the striking point. Since the rod-shaped member is rotatable, the hammer collides with the object in a state where the movement in the tangential direction of the rotation is allowed. Accordingly, appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained.

  Moreover, in the physical-property evaluation apparatus of this invention, it is preferable that the length of a rod is 2 m or more. Considering the case where the physical property evaluation device is applied to the evaluation of the face of the tunnel under construction, in general, the area within 2m from the face is likely to cause a skin fall, falling rocks, etc., and the worker is 2m from the face. Approaching within is considered to be especially avoided. According to the above configuration, even when the deformation characteristics of the working face of the tunnel under construction are evaluated, the operator can work 2 m or more away from the working face.

  According to the physical property evaluation apparatus of the present invention, physical property evaluation of an object based on Hertz's elastic contact theory can be easily performed even when an operator's hand is difficult to reach the hitting point.

It is a figure which shows 1st Embodiment of the physical property evaluation apparatus which concerns on this invention, and its usage. It is a partially broken side view which expands and shows the hit | damage part of the physical property evaluation apparatus shown in FIG. It is a side view which expands and shows the hit | damage part of 2nd Embodiment of the physical property evaluation apparatus which concerns on this invention. (A)-(d) is a figure which shows the waveform of each acceleration data obtained by the test 1 of the present inventors. It is a graph which shows the result of other tests 2 by the present inventors. It is a graph which shows the result of other tests 3 by the present inventors.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a physical property evaluation apparatus according to the invention will be described in detail with reference to the drawings.

(First embodiment)
A physical property evaluation apparatus 1 shown in FIG. 1 is an apparatus that strikes an evaluation object and analyzes an impact waveform at the time of impact to evaluate deformation characteristics of the evaluation object. For example, the physical property evaluation apparatus 1 can obtain the deformation coefficient (relationship between stress and strain) of the rock mass 53 using the rock mass 53 of the face 51 of the tunnel 90 under construction as an evaluation object. And based on the obtained deformation coefficient of the rock 53, the specification of the support work to be performed near the face 51 can be appropriately set.

  As shown in FIG. 1, the physical property evaluation apparatus 1 includes a rod 3 that extends linearly. The length of the rod 3 is 2 m or more, and for example, a metal pipe or the like is used as the rod 3. At one end of the rod 3, a striking portion 5 that strikes a striking point 53 a of the bedrock 53 is provided. As shown in the figure, the worker A uses the physical property evaluation apparatus 1 while holding the other end of the rod 3. Hereinafter, the extending direction of the rod 3 is the front-rear direction, the end on the side where the striking portion 5 is provided is the “front end”, and the end on the side held by the worker A is the “rear end” Words including the concepts of “before” and “after” are used for explaining the positional relationship.

  The physical property evaluation apparatus 1 further acquires a shock waveform (acceleration data) obtained by the striking unit 5, and analyzes the shock waveform to calculate a deformation coefficient of the rock 53 (acceleration data acquisition means, calculation means) 7 It has. As the computer 7, a commercially available personal computer storing a predetermined evaluation program can be used.

  Next, with reference to FIG. 2, the structure of the hit | damage part 5 is demonstrated. As shown in the drawing, the striking portion 5 includes a hammer 13 positioned in front of the rod body 3, and as a connecting portion for connecting the rod body 3 and the hammer 13, a slide mechanism (movement allowing portion) 13 and an urging force are provided. Part 17.

  The hammer 13 is a metal sphere having a diameter of about 5 cm, for example, and the front surface of the spherical hammer 13 forms a striking surface 13a that collides with the striking point 53a. In applying Hertz's elastic contact theory, which will be described later, it is not essential that the entire hammer 13 is spherical, and at least the striking surface 13a may be spherical. The hammer 13 is not necessarily made of metal, and the material of the hammer 13 may be rubber, wood, plastic, ceramic, or the like. An acceleration sensor 15 is attached to the rear surface of the hammer 13. The acceleration sensor 15 measures acceleration in the collision direction at the time of collision between the striking surface 13a and the striking point 53a. That is, when the hit point 53 a is hit with the hammer 13, the acceleration sensor 15 detects an impact waveform generated by a collision between the hit surface 13 a and the rock 53 as an acceleration waveform. The detected acceleration waveform is transmitted as an acceleration signal to the computer 7 via the data cable 15a or the like.

  The slide mechanism 11 is provided in a hollow portion at the front end of the rod 3 and includes a fixed rail 11b and a movable rail 11a engaged with the fixed rail 11b so as to be movable back and forth. The fixed side rail 11 b is fixed to the inner wall surface of the hollow portion of the bar 3, and the front end of the moving side rail 11 a protrudes forward from the front end opening of the bar 3. The hammer 13 is attached to the front end of the moving side rail 11a. With such a structure, the hammer 13 can move in parallel with the rod 3 in the front-rear direction (the extending direction of the rod 3). Further, in the slide mechanism 11, the front-rear limit and the rear-end limit exist in the movement range of the hammer 13 because the movement range of the moving rail 11 a is limited by a predetermined stopper mechanism (not shown).

  As the slide mechanism 11, for example, a known slide rail part having a structure in which a ball is sandwiched between the fixed side rail 11b and the moving side rail 11a may be used. The slide mechanism 11 may have another structure as long as it supports the hammer 13 so as to be movable back and forth.

  Further, the striking part 5 includes a biasing part 17 that biases the hammer 13 forward. The urging portion 17 includes two arms 19 that can be opened and closed by hinge coupling, and a torsion spring 21 that urges the arms 19 in the opening direction. Since the tips of the two arms 19 are hinged to the moving side rail 11a and the outer wall surface of the rod body 3, respectively, the urging force of the torsion spring 21 acts as a force for urging the hammer 13 forward. . The force generated by the torsion spring 21 is adjusted to zero when the hammer 13 is at the front end limit position. When the hammer 13 is retracted from the front end limit position, the torsion spring 21 is moved to the hammer position. Demonstrates the force to push 13 forward.

  Based on the above configuration, as shown in FIG. 1, the worker A can hit the hit point 53a with the hammer 13 by holding the rear end side of the rod 3 and pushing the hit point 53a. . As described above, the acceleration signal reflecting the impact waveform at the time of impact is transmitted from the acceleration sensor 15 to the computer 7 via the data cable 15a and the like.

Subsequently, the computer 7 executes a predetermined evaluation program stored in advance to calculate an elastic coefficient of the rock mass 53 using Hertz's elastic contact theory based on the acceleration signal (impact waveform). According to Hertz's elastic contact theory, the contact time between the sphere and the elastic plane when the sphere collides with the elastic surface is expressed by the following equation (1).

However,
E ₁ : Elastic coefficient of the sphere μ ₁ : Poisson's ratio of the sphere R: Radius of the sphere M: Mass of the sphere E ₂ : Elastic coefficient of the elastic body μ ₂ : Poisson's ratio of the elastic body V ₀ : Collision speed.

Patent Document 1 discloses that Hertz's elastic contact theory as described above is used for measuring the rigidity of a concrete structure. In this embodiment, Hertz's elastic contact theory is applied when measuring the deformation coefficient of the rock mass 53. That is, in the present embodiment, in the Hertz elastic contact theory, the hammer 13 is applied to the sphere, and the rock mass 53 is applied to the elastic body. In this case, E ₁ , μ ₁ , R, and M are known in the equation (1). Moreover, as the Poisson's ratio μ ₂ of the rock 53, a value of 0.2 may be used as the Poisson's ratio of a general rock mass. Furthermore, T _c and V ₀ can be calculated from the impact waveform represented by the acceleration signal. Therefore, as long obtained acceleration signal, may be based on the equation (1) to calculate the elastic modulus (deformation coefficient) E ₂ of the rock 53 is unknown amount.

  Then, the effect by the physical-property evaluation apparatus 1 is demonstrated.

Generally, there is a risk of falling rocks, skin falling, etc. near the face, so from the viewpoint of preventing work accidents, the worker A should avoid approaching the face 51 of the tunnel 90 under construction. For example, in the following press release, there is a statement that "80% or more of work accidents near the tunnel face occur within 2m from the face", and worker A is an area within 2m from the face. Going into is considered to be especially avoided. Therefore, the worker A cannot approach within 2 m from the hitting point 53a.
[Press Release] Kashima Construction Co., Ltd. Press Release, “Loading Gunpowder from a Position 2m from the Face”, October 7, 2008,
(URL: http://www.kajima.co.jp/news/press/200810/7c1-j.htm)

  On the other hand, according to the physical property evaluation apparatus 1, the front end portion of the rod body 3 in a state where the worker A holds the rear end side of the rod body 3 by the configuration in which the hitting portion 5 is provided at the front end portion of the rod body 3. The worker A himself / herself can hit the hit point 53a with the hammer 13 without approaching the hit point 53a. In particular, since the length of the rod 3 is 2 m or more, the worker A does not have to enter an area (within 2 m from the face) where entry should be avoided. Further, considering the length of the rod 3 held by the operator A, the entire length of the rod 3 may be 2.5 m or more.

  However, when the rod 3 is too long, the handling by the operator A becomes difficult, and there is a problem that the rod 3 cannot be hit in an appropriate hitting direction due to the deflection of the rod 3. Therefore, the length of the rod 3 is preferably 3.5 m or less. That is, the length of the rod 3 is preferably 2.0 to 3.5 m, and more preferably 2.8 to 3.2 m among them.

  Further, in order to obtain appropriate acceleration data applicable to Hertz's elastic contact theory, it is necessary to hit the rock 53 in a state where the movement of the hammer 13 due to repulsion at the moment of impact is allowed. That is, at the moment of hitting, the movement of the hammer 13 elastically rebounding from the rock 53 should not be hindered. Here, a structure in which the hammer 13 is simply fixed to the front end of the rod 3 is considered. According to the apparatus of this structure, when the worker A performs an operation of piercing the hit point 53a, it is easy to perform an operation of pushing forward further for a certain time immediately after the collision between the hammer 13 and the rock mass 53, that is, the hammer 13 It tends to be in a state where the movement of bouncing back is hindered. Furthermore, since the hammer 13 is located away from the worker A and is difficult to see, it is difficult for the worker A to finely adjust the hammering state of the hammer 13. Therefore, with the structure in which the hammer 13 is simply fixed to the front end portion of the rod body 3, it is difficult to obtain appropriate acceleration data applicable to Hertz's elastic contact theory.

  On the other hand, according to the physical property evaluation apparatus 1, the hammer 13 employs a configuration in which the hammer 13 is supported so as to be movable in the collision direction (front-rear direction) with respect to the rod body 3. Specifically, since the hammer 13 is connected to the rod body 3 via the slide mechanism 11, the hammer 13 is allowed to move backward due to repulsion from the rock 53 at the moment of hitting. It is. Accordingly, appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained.

  Further, since the rod body 3 is quickly accelerated forward during the piercing operation, the hammer 13 tends to move backward with respect to the rod body 3 due to inertia. At this time, if the hammer 13 reaches the rear end limit, the backward movement of the hammer 13 at the moment of impact is limited, and appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained. become unable.

  On the other hand, in the physical property evaluation apparatus 1, by providing the urging portion 17, the hammer 13 is urged forward by the urging portion 17 when the rod body 3 is accelerated. You can avoid reaching the limit. Therefore, even when the rod 3 is accelerated quickly, it is possible to ensure the backward movement of the hammer due to repulsion and obtain appropriate acceleration data applicable to Hertz's elastic contact theory.

  It should be noted that, at the moment of hitting, the forward biasing force by the biasing portion 7 is acting, and the movement of the hammer 13 to the rear is slightly hindered. Compared with this, the influence of the urging force can be ignored.

(Second Embodiment)
Then, 2nd Embodiment of the physical-property evaluation apparatus of this invention is described. The physical property evaluation apparatus 101 according to the present embodiment is provided with a hitting unit 105 shown in FIG. 3 at the tip of the rod 3 instead of the hitting unit 5. About the other structure of the physical property evaluation apparatus 101, since it is the same as that of the physical property evaluation apparatus 1 of 1st Embodiment, the overlapping description is abbreviate | omitted. 3, the same or equivalent components as those in FIG. 1 or FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 3, the hitting portion 105 includes a connecting bar (bar-shaped member) 111 that connects the bar 3 and the hammer 13. The upper end of the connecting bar 111 is rotatably supported by the bar 3 at the hinge 111a. The connecting bar 111 is rotatable in a vertical plane (in a plane parallel to the extending direction of the bar 3) around the hinge portion 111a. A hammer 13 is attached to the lower end of the connecting bar 111. The acceleration sensor 15 detects the acceleration in the tangential direction of the rotation trajectory of the hammer 13. A string 113 having the same length as that of the bar 3 is attached to the connecting bar 111. With the above configuration, the hammer 13 can swing in the front-rear direction around the hinge portion 111a.

  In using the physical property evaluation apparatus 101, the worker A is in a state where the bar 3 of the physical property evaluation apparatus 101 is substantially horizontal and the rear end portion is held, as in FIG. The worker A can pull the hammer 13 backward by inclining the connecting bar 111 by pulling the rear end portion of the string 113. In this state, if the tip of the rod 3 is brought close to the rock mass 53 (or brought into contact with the rock mass 53) and the string 113 is released, the hammer 13 swings forward by its own weight, and the striking surface 13a and the striking point 53a Collide. The operator A can hit the hit point 53a with the hammer 13 by the operation as described above.

  According to this physical property evaluation apparatus 101, the hammer A can hit the hit point 53 a with the hammer 13 without approaching the hit point 53 a due to the configuration in which the hit portion 105 is provided at the front end of the bar 3. . Further, since the hammer 13 can swing back and forth, the hammer 13 is allowed to move in the collision direction (the tangential direction of the rotation track of the hammer 13) due to the repulsion from the rock 53 at the moment of hitting. Accordingly, appropriate acceleration data applicable to Hertz's elastic contact theory can be obtained.

  Further, by adjusting the amount of pulling the string 113, the swing width of the hammer 13 at the time of striking can be easily adjusted, and the striking energy can be easily adjusted.

  The present invention is not limited to the first and second embodiments described above. For example, in the embodiment, an example in which the physical property evaluation apparatus is applied to evaluation of a face of a tunnel has been described. However, the physical property evaluation apparatus of the present invention can also be used for evaluation of side wall concrete of a tunnel. In tunnel construction, after blasting or excavating with a machine, the rock mass is exposed not only on the face but also on the side wall near the face. The physical property evaluation apparatus of the present invention can also be applied to the evaluation of the rock exposed on the side wall. Here, the side wall portion in the vicinity of the face is a portion of the side wall in front of the face and indicates a range within a predetermined distance in the tunnel axis direction when viewed from the face. The predetermined distance is, for example, 0.5 m to 2.0 m. Even in the evaluation of tunnel side wall concrete and rocks on the side wall as described above, it is sometimes necessary to hit a high position. Conventionally, if the worker's hand does not reach the hit point, the tunnel We had to work with the scaffolding inside, and it took time and effort. However, according to the physical property evaluation apparatus of the present invention, hitting points that are hard to reach by the operator are hit and appropriate acceleration data is obtained, so that work efficiency can be improved.

  In the first and second embodiments, the acceleration signal is transmitted from the acceleration sensor 15 to the computer 7 via the data cable 15a. However, the acceleration signal may be transmitted from the acceleration sensor 15 to the computer 7 by wireless communication. Good. In this case, the data cable 15a is omitted, and the limitation on the action range of the worker A is reduced.

  Further, an electronic storage medium capable of storing and storing acceleration data (impact waveform) is employed in place of the computer 7 provided with the calculation means, and the obtained acceleration data is stored and stored as electronic data in the electronic storage medium. It is good to go. In this case, an operation in which acceleration data stored in the electronic storage medium is batch processed by a computer afterwards can be considered. Since electronic storage media are generally smaller and lighter than the computer 7 having an arithmetic function, the electronic storage media can be attached to the rod 3. By adopting a small and lightweight electronic storage medium, the handling burden of the physical property evaluation apparatuses 1 and 101 by the worker A is reduced. As the electronic storage medium, a semiconductor memory, a hard disk device, or the like can be used.

  Subsequently, a test conducted by the present inventors in order to confirm the above-described effects by the physical property evaluation apparatuses 1 and 101 will be described.

[Test 1]
The inventors of the present invention have a physical property evaluation device 1, a physical property evaluation device 101, a device having a structure in which a hammer 13 is simply fixed to the front end portion of the rod 3 (hereinafter referred to as “comparison device”), and the above-mentioned Patent Document 1. Using the apparatus (hereinafter referred to as “reference apparatus”), a test for hitting an object was performed. The hit object of the physical property evaluation apparatus 1 and the reference apparatus is mudstone, and the hit object of the comparison apparatus is mortar. FIG. 4A shows acceleration data (impact waveform: time is on the horizontal axis and acceleration is on the vertical axis) obtained by striking using the physical property evaluation apparatus 1, the physical property evaluation apparatus 101, the comparison apparatus, and the reference apparatus, respectively. , (B), (c), (d).

  As shown in FIG. 4 (d), in the reference device, the gripping object extending to the side of the spherical hammer is gripped and the target is hit by the swinging motion of the hammer, so that the hammer rebounds at the moment of hitting. It is difficult to be in a state, and ideal acceleration data is obtained.

  On the other hand, as shown in FIG. 4 (c), the acceleration data obtained by the comparison device is a waveform indicating vibration and cannot be applied to Hertz's elastic contact theory, and the deformation coefficient of the object is analyzed. Was impossible. This is considered to be caused by the operation of pressing the hammer 13 further forward immediately after the impact.

  On the other hand, as shown in FIG. 4A, according to the physical property evaluation apparatus 1, ideal acceleration data similar to that of the reference apparatus was obtained. This is due to the fact that the hammer 13 was allowed to move due to the repulsion of the hit and was caused by the action of the slide mechanism 11 and the urging portion 17.

  Similarly, as shown in FIG. 4B, ideal acceleration data similar to that of the reference apparatus was obtained by the physical property evaluation apparatus 101. This is due to the fact that the hammer 13 was struck in a state where the movement of the hammer 13 due to the repulsion of the hammer was allowed, and is considered to result from the configuration in which the hammer 13 can be easily rotated. From the above, the above effects by the physical property evaluation apparatus 1,101 were confirmed.

[Test 2]
The present inventors selected a total of 10 measurement points that are considered to have three different strengths on the side wall of an already excavated tunnel of about 2000 m. Each measurement point is selected from three different rock classification points. Three rock classification points are equivalent to class B or higher, and rock classifications are points corresponding to B to CI classes. Five points were selected, and two points were selected where the rock classification was equivalent to CII-D class. The rock classification at each point is determined in advance by observation of a geological engineer. The type of rock on the side wall of the tunnel is basalt.

On the other hand, the following document 1 shows the relationship between the rock classification of natural ground and the deformation coefficient as shown in Table 1 below.
Reference 1: “Public Works Research Institute Data: Prediction and countermeasure manual for ground deformation during tunnel excavation (draft)”, Ministry of Construction, Civil Engineering Research Institute, Tunnel Laboratory, February 1994, p. 20.

Moreover, the relationship between the rock classification and the deformation coefficient as shown in Table 1 is considered to be appropriate in light of the description in the following document 2 (particularly, Table-7 on page 112).
Reference 2: Hirokichi Kikuchi et al. “Comprehensive geotechnical evaluation of load resistance of dam foundation rock”, Applied Geology, Japan Society of Applied Geology, 1984, Special Issue, p. 103-118.

  The present inventors obtained the deformation coefficient of the side wall surface at each measurement point using the above-described reference device, the physical property evaluation device 1, and the physical property evaluation device 101. The measured value of the deformation coefficient at each measurement point in each device is averaged separately for each rock classification at the measurement point, and is shown as a graph in FIG.

  As a result of this test, as shown in FIG. 5, according to the measurement using each device, an appropriate deformation coefficient corresponding to the rock classification at each point was obtained as a measured value in view of Table 1 above. . In other words, it has been found that the above-described devices can provide reasonable results of deformation coefficient measurement, and the physical property evaluation apparatuses 1 and 101 can measure the correct deformation coefficient of an object as in the reference apparatus. It was confirmed.

[Test 3]
The inventors selected two measurement points (the right side surface and the left side surface of the tunnel) on the side wall surface of the tunnel. The side walls of the selected measurement points are all mudstone. And the deformation coefficient of each measurement point was calculated | required using the physical-property evaluation apparatus 1. FIG. Separately, the deformation coefficient at each measurement point was determined using the “in-hole horizontal loading test method” established as a standard of the Geotechnical Society (JGS1421-2003). The deformation coefficient obtained by each method is shown in FIG.

  As shown in FIG. 6, when the physical property evaluation apparatus 1 was used, almost the same deformation coefficient as in the in-hole horizontal loading test was obtained at both the measurement points (1) and (2). Therefore, it is considered that the measured value of the deformation coefficient by the physical property evaluation apparatus 1 has the same reliability as the in-hole horizontal loading test. Therefore, the measurement of the deformation coefficient by the physical property evaluation apparatus 1 can be used for the same purpose as the in-hole horizontal loading test. Similarly, the above-described reference device and physical property evaluation device 101 have the same reliability as the in-hole horizontal loading test and can be used for the same purpose as the in-hole horizontal loading test. Hereinafter, the physical property evaluation apparatuses 1, 101 and the above-described reference device are collectively referred to as “physical property evaluation apparatus 1”.

  Further, if the reliability of the measured value is equivalent to that in the in-hole horizontal loading test, the purpose and application of the deformation coefficient measurement by the physical property evaluation apparatus 1 or the like can be expanded to the same extent as in the in-hole horizontal loading test. For example, as an example of application of deformation coefficient measurement by the physical property evaluation apparatus 1 or the like, an example applied to tunnel construction will be considered below. In tunnel construction, the geological consultant is in charge of the planning and survey stage. Usually, the elastic wave velocity distribution of the whole natural ground to be excavated is investigated by elastic wave exploration, and the natural ground is evaluated based on the velocity value. . In addition, drilling and electrical exploration are performed as necessary.

  Thereafter, a standard design may be applied in designing the tunnel support structure. That is, a typical support structure corresponding to the ground grade is determined for each company, based on the past construction results, and the determination (standard design) may be applied to the design of the support structure. As another method for designing the support structure, an analytical method may be applied. That is, the support structure may be designed by theoretical analysis or numerical analysis (FEM or the like). At this time, as a deformation coefficient of the natural ground used in the theoretical analysis and the numerical analysis, the result of the above-mentioned horizontal loading test in the hole may be used. Instead, the deformation by the physical property evaluation apparatus 1 or the like may be used. It is conceivable that a measure of the coefficient can also be used. That is, it is considered that the measured value of the deformation coefficient by the physical property evaluation apparatus 1 or the like can be used for theoretical analysis or numerical analysis (FEM or the like) in natural ground evaluation.

  Furthermore, at the tunnel construction stage, while reassessing whether the actual natural ground was the same as the originally predicted natural ground, from the viewpoint of rationality and economic efficiency, a support structure was established as necessary. May change. At this time, the measurement of the deformation coefficient by the physical property evaluation apparatus 1 or the like can be employed as a technique for re-evaluating the natural ground in place of the in-hole horizontal loading test.

  In addition, the in-hole horizontal loading test is relatively troublesome, such as the need for boring, and the measurement time per point is also relatively long. Compared to this, the measurement of the deformation coefficient by the physical property evaluation apparatus 1 or the like is easier than the measurement work, is relatively less troublesome, and requires a shorter measurement time than the in-hole horizontal loading test. Are better. Therefore, the measurement of the deformation coefficient by the physical property evaluation apparatus 1 or the like is relatively easy to increase the number of measurement points as compared with the in-hole horizontal loading test, and more detailed evaluation and re-evaluation of the ground can be performed. .

DESCRIPTION OF SYMBOLS 1 ... Physical property evaluation apparatus, 3 ... Rod, 5 ... Blowing part, 7 ... Computer (acceleration data acquisition means, calculation means), 11 ... Slide mechanism (connection part, movement allowance part), 13 ... Hammer, 13a ... Battering surface , 15 ... acceleration sensor, 17 ... urging unit (connecting unit, urging unit), A ... worker.

Claims (6)

A physical property evaluation apparatus for evaluating physical properties of an object,
A rod for the operator to hold the rear end,
A hammer connected to the front end of the rod and having an acceleration sensor and a spherical striking surface;
Acceleration data acquisition means for acquiring acceleration data for calculating deformation characteristics of the object from the acceleration sensor when the hitting surface of the hammer collides with the object;
With
The hammer is
An apparatus for evaluating physical properties, characterized in that the rod is supported so as to be movable in a collision direction between the striking surface and the object. The acceleration data acquisition means includes
The physical property evaluation apparatus according to claim 1, further comprising a calculation unit that calculates a deformation characteristic of the object based on the acquired acceleration data. The acceleration data acquisition means includes
The physical property evaluation apparatus according to claim 1, wherein the physical property evaluation apparatus is an electronic storage medium that stores the acquired acceleration data as electronic data. The connecting portion between the rod and the hammer is
A movement allowing portion that enables the hammer to move parallel to the rod body in the extending direction of the rod body;
The physical property evaluation apparatus according to claim 1, further comprising: an urging portion that urges the hammer forward. The connecting portion between the rod and the hammer is
The hammer is provided at one end, and the other end has a rod-like member supported so as to be rotatable with respect to the rod in a plane parallel to the extending direction of the rod. The physical property evaluation apparatus according to any one of 1 to 3. The physical property evaluation apparatus according to claim 1, wherein the length of the rod is 2 m or more.

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