JP2008096416A - Calibration method for tension force detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration method for a tension force detector capable of carrying out proper calibration processing by simple work. <P>SOLUTION: A ground anchor 10 has an anchor cable 11 arranged penetrated through concrete 12, and arranged to bury a lower end part in the ground, and to project an upper end part from the concrete 12, an anchor head 13, and an anchor plate 14. This tension force detector of the present invention has a sensor plate 20 arranged between the anchor head 13 and the concrete 12, and a strain sensor for detecting a strain generated in the sensor plate 20. In the calibration processing, tensile force is applied onto the anchor cable 11 along a longitudinal direction thereof, and tension force is changed thereby to detect a relation between pressing force acting on the sensor plate 20 from the anchor cable 11 via the anchor head 13 and the strain generated in the sensor plate 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a calibration method for a tension detecting device that detects tension of a ground anchor used for applying tension in prestressed concrete, retaining earth on slopes, and the like.

  Ground anchors are used for applying tension in prestressed concrete laid on the ground and retaining earth on slopes.

  FIG. 23 shows a typical ground anchor 100. In FIG. 23, reference numeral 101 denotes a concrete member that is laid on the ground slope and the like and should be pressed to the ground side by the ground anchor 100, 102 is an anchor plate placed on the surface of the concrete member 101, and 104 is a resin sheath. , 106 is an anchor cable which is a tension member, 108 is an anchor head fixed to the anchor cable 106, and 109 is a cap having a function of preventing the anchor cable 106 from being corroded.

  The concrete member 101 and the anchor plate 102 are formed with insertion holes substantially coaxially. An anchor cable 106 accommodated in the sheath 104 is inserted through these insertion holes.

  The lower end of the anchor cable 106 is fixed to an anchor body (not shown) embedded in a stable ground in the ground below the concrete member 101. An anchor head 108 is fixed to an upper end portion of the anchor cable 106 led out from the insertion hole of the concrete member 101 and the anchor plate 102 to the ground side.

  The anchor head 108 is fixed to the anchor cable 106 that is in a tensioned state by pulling the upper end portion of the anchor cable 106 with a jack or the like, and is pressed toward the anchor plate 102 by a tension force acting via the anchor cable 106. It is fixed.

  In such a ground anchor 100, the tension applied to the anchor cable 106 may be loosened due to secular change, and the initial support strength by the anchor cable 106 may be reduced. Therefore, it is necessary to periodically check the tension of the anchor cable 106.

  Conventionally, various tension detecting devices have been proposed for detecting the tension of the anchor cable 106 in the installed ground anchor 100.

  For example, as shown in FIG. 24, the anchor plate 133 that receives the tension force of the anchor cable 123 is provided with a strain sensor 141 that detects the amount of bending strain of the anchor plate 133, and the bending strain detected by the strain sensor 141 is provided. There has been proposed a ground anchor tension detection system 110 including a tension monitor 144 that calculates a decrease in tension of the tension measuring device of the anchor cable 123 from the amount (see, for example, Patent Document 1).

In FIG. 24, reference numeral 131 is concrete, 129 is ground, 127 is an anchor body, 135 is an anchor head, 139 is an anchor cable 123, a wedge inserted between the anchor heads 135, and 136 is a cap.
JP 2006-162511 A

  However, in the conventional tension detecting device, the calibration process of the strain sensor may not be properly performed, and there is a possibility that the tension cannot be accurately detected.

  For example, when detecting the tension of the ground anchor using the ground anchor tension detection system 110 of Patent Document 1, if the surface of the concrete 131 is uneven, the pressing force applied to the anchor plate 133 by the tension of the anchor cable 123 Depends on the position of the anchor plate 133. For this reason, the bending distortion generated in the anchor plate 133 differs depending on the position of the anchor plate 133.

  For this reason, the bending strain detected by the strain sensor 141 attached to the anchor plate 133 differs depending on the attachment position of the strain sensor 141.

  In addition, since the installation environment of the ground anchor 100 is different for each ground anchor 100, even if the tension force of the anchor cable 106 is the same, the bending strain detected by the strain sensor 141 is different for each ground anchor 100. There are many.

  Therefore, when measuring the tension of the ground anchor 100, it is necessary to appropriately perform the calibration process of the ground anchor tension detection system 110 and the like. However, as described above, conventionally, an appropriate calibration process has been performed. There wasn't.

  In addition, since the calibration process of the ground anchor tension detection system 110 is often performed in a place where the scaffolding is poor, it is desirable that the calibration process can be simplified.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a calibration method for a tension detecting device that can perform an appropriate calibration process with a simple operation.

The present invention employs the following means in order to solve the above problems.
That is, the present invention
A calibration method for performing a calibration process of a tension detecting device that detects a tension of a ground anchor that applies a pressing force to the ground to a laying member laid on the ground,
The ground anchor is disposed through the laying member, a lower end is embedded in the ground, and an upper end projects from the laying member, and an upper end of the tension member. A fixed anchor head, and an anchor plate disposed between the anchor head and the laying member,
The tension detection device has a strain detection plate disposed between the anchor head and the laying member, and a strain detection means for detecting strain generated in the strain detection plate,
In the calibration process, a tension force is applied to the tension member along the longitudinal direction thereof to change the tension force, and a pressing force acting on the strain detection plate from the tension member via the anchor head; It is characterized by detecting the relationship with the strain generated in the strain detection plate.

  In the present invention, for example, before the tension force of the tension member is detected by the tension force detection device, a tensile force is applied to the tension member and the strain force is applied to the strain detection plate via the anchor head, and the strain is detected. By obtaining the relationship with the distortion generated in the detection plate, the calibration process can be performed easily and appropriately.

  When detecting the tension force of the tension member by the tension force detection device, a tensile force is applied to the tension member, the strain generated in the strain detection plate is detected, and the detected pressure is determined by the calibration process. The pressing force acting on the strain detection plate is obtained by collating with the relationship. Based on this pressing force, the tension force of the tension member can be accurately calculated.

  Further, in the calibration process, the means for applying a tensile force to the tension member and the means for detecting the strain of the strain detection plate can use each means of the tension detection device. No work is required and the calibration process can be performed easily. Examples of the tension member include a tension wire, a tension steel rod, a tension member formed on the upper side with a tension steel rod and the lower side with a tension wire.

  Here, examples of the strain include compression strain and bending strain.

Further, the tension detecting device is provided with a plurality of strain detecting means,
The calibration process calculates an average value of the distortions excluding the distortions out of a predetermined range among the distortions detected by the plurality of distortion detection units, and uses the average value to calculate the distortions and the distortions. The relationship with the pressing force can be obtained.

  In this case, since the strain detection means is provided at a plurality of positions of the strain detection plate, it is possible to appropriately detect the strain even when the pressing force acting on the strain detection plate varies depending on the position.

  In addition, the relationship between the pressing force and the strain can be obtained both when increasing and decreasing the tensile force applied to the tension member.

  In this case, an appropriate calibration process can be performed even when hysteresis occurs between the pressing force acting on the strain detection plate and the strain.

  Further, after the anchor head collides with the strain detecting plate, the relationship between the pressing force and the strain can be obtained.

  In this case, when the contact state between the anchor head and the strain detection plate is not uniform, the contact state can be improved by causing the anchor head to collide with the strain detection plate.

  Moreover, it is preferable to obtain the relationship between the pressing force and the strain by setting the tensile force applied to the tension member to a predetermined value or less.

  In this case, strain detection in a range where the tensile force exceeds a predetermined value can be omitted, so that the number of work steps can be reduced.

Further, the tensile force is applied to the tension member until the anchor head is separated from the strain detection plate,
Find the inflection point in the relationship between the tensile force and the amount of elongation of the tension member,
The tensile force at the inflection point is applied to the tension member to detect distortion of the strain detection plate,
The relationship between the tensile force and the strain can be obtained based on a straight line connecting the point indicating the relationship between the tensile force and the strain at the inflection point and the origin of the tensile force and the strain.

  In this case, since only the relationship between the tensile force and strain at the inflection point has to be obtained, the work can be shortened.

  In addition, the relationship between the tensile force and the strain can be obtained by removing the strain that is out of a predetermined range from the strain detected by the plurality of strain detection means.

  In this case, out of the distortions detected by the plurality of distortion detection means, only the appropriate distortion is used except for the specific distortion, so that more accurate calibration processing can be performed.

  Further, when there is the distortion outside the predetermined range, an alarm or warning can be generated.

  In this case, an alarm or warning is generated when the distortion deviates from the predetermined range due to some malfunction, so that the malfunction can be immediately recognized and appropriate measures can be quickly performed.

  Further, the relationship between the load and the strain can be obtained based on the average value of the strain detected by the plurality of strain detecting means. An arithmetic average can be illustrated as an average value.

  In this case, since the average value of the distortion is used when the distortions detected by the plurality of distortion detectors are different, an appropriate calibration process can be performed.

  According to the present invention, before measuring the tension of the ground anchor by the tension detector, the calibration process is performed by obtaining the relationship between the pressing force and the strain acting on the strain detection plate using the tension detector. Therefore, the calibration process can be performed easily and appropriately.

  In addition, by using a plurality of strain detection means, it is possible to detect strain at a plurality of positions of the strain detection plate. For example, the surface of the laying member has irregularities, and the pressing force acting on the strain detection plate varies depending on the position. Even in this case, it is possible to appropriately detect the strain of the strain detection plate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

<< First Embodiment >>
FIG. 1 is a diagram for explaining a calibration method of the tension detecting device 1 according to the first embodiment of the present invention. In addition, although this embodiment demonstrates the case where it applies to the tension detecting device of the ground anchor which gives tension to the concrete laid on the slope, this invention is not limited to this, The tension of the ground anchor It can be applied to the calibration of various tension detecting devices for detecting the tension.

  The ground anchor 10 is disposed through the concrete 12 so as to apply a pressing force toward the ground 15 to the concrete 12 that is a laying member laid on the ground 15, and a lower end portion of the ground anchor 10 is attached to the anchor body 30 in the ground 15. An anchor cable 11 that is fixed and has an upper end protruding above the concrete 12, an anchor head 13 that is disposed above the concrete 12 and is fixed to the upper end 11 a of the anchor cable (tension member) 11, and the anchor cable 11 The anchor plate 14 is provided between the anchor head 13 and the concrete 12 in order to transmit the pressing force by the above to the concrete 12 through the anchor head 13.

  An oil cap 61 (see FIG. 7) is fitted to the upper end portion 11a of the anchor cable 11. The anchor body 30 is formed in a predetermined size and shape by injecting a cement grout material. The anchor cable 11 is inserted through a resin sheath 31 having predetermined elastic characteristics. In addition to the anchor cable 11 that is a tension wire, examples of the tension member include a tension steel rod, an upper portion formed of a tension steel rod, and a lower portion formed of a tension wire.

  The anchor cable 11 and the anchor head 13 are fixed by inserting the anchor cable 11 into a wire insertion hole 13a formed in the anchor head 13, and inserting a tapered tubular wedge between the inner surface of the wire insertion hole 13a and the anchor cable 11. It is done by typing.

  The tension detection device 1 detects the tension of the anchor cable 11 in the ground anchor 10.

  That is, the tension detecting device 1 includes a sensor plate 20 that is a strain detecting plate disposed between the anchor head 13 and the anchor plate 14, and a strain detecting unit that detects a compressive strain generated in the sensor plate 20. It has the distortion sensor 21 which is.

  As shown in FIG. 2, the sensor plate 20 has a plurality of divided plates 20a. In the present embodiment, there are three divided plates 20a. These divided plates 20a are formed in a substantially rectangular shape, and have relatively large chamfers C at both outer corners.

  The three divided plates 20a are arranged in a substantially C shape so as to surround the plurality of anchor cables 11 of the ground anchor 10 (see FIG. 5). Moreover, the electric wire 22 extended from the control part 50 (refer FIG. 6) is connected to the approximate center part in the center division | segmentation plate 20a.

  Further, the central divided plate 20 a and the other divided plate 20 a are connected by a linear connecting member 23. And the clearance gap D is formed between the division | segmentation plates 20a and 20a of both sides.

  That is, the three divided plates 20a are connected in series and arranged so as to form a substantially C shape, and both ends thereof are open. These division | segmentation plates 20a are formed with the rust prevention steel plate adsorb | sucked to a magnet.

  The connecting member 23 is formed in a linear shape from an elastic material. Due to the elasticity of the connecting member 23, each divided plate 20a is urged toward the inside of the C-shape.

  An electric wire 24 is provided along the connecting member 23. Both ends of the electric wire 24 are connected to the strain sensors 21 and 21 of the adjacent divided plates 20a and 20a.

  As shown in FIG. 3, a rectangular hole 20b is provided in the approximate center of each divided plate 20a. A strain sensor 21 is provided in the hole 20b as shown in FIG.

  In the present embodiment, the strain sensor 21 is attached to the inner surface 20c of the hole 20b. The strain sensor 21 detects a compressive strain in the thickness t direction of the divided plate 20a.

  In this embodiment, the case where one strain sensor 21 is provided on one divided plate 20a is shown, but the same applies to the case where a plurality of strain sensors 21 are provided on one divided plate 20a. . A commercially available strain gauge is used for the strain sensor 21.

  Further, the strain sensor 21 needs to be provided with a high degree of weather resistance (waterproofness) in order to prevent contamination due to outside air, moisture, or the like. Therefore, in this embodiment, after the strain sensor 21 is attached in the hole 20b, the coating agent (waterproof resin) 25 is potted and buried in the hole 20b. Further, the opening of the hole 20b may be subjected to waterproofing treatment such as covering with a waterproof lid.

  As shown in FIG. 5, each divided plate 20 a of the sensor plate 20 is housed and attached between an outer peripheral edge 13 b of the anchor head 13 and a circumference 11 d that passes through the outer ends of all anchor cables 11. .

  FIG. 6 shows the control unit 50 in the tension detecting device 1 for the ground anchor. The control unit 50 includes a substrate box 51 and a tension monitoring device 52. The board box 51 and the tension monitor 52 are formed separately from each other.

  The substrate box 51 includes a parallel circuit 53 that reads an output signal of the strain sensor 21 and a storage medium 54. The parallel circuit 53 is connected to the strain sensor 21 of the divided plate 20a. The storage medium 54 may be an EEPROM (Electronically Erasable and Programmable Read Only Memory).

The tension monitor 52 includes a strain sensor operating circuit 55 having an amplifier circuit for amplifying a received signal from the parallel circuit 53, and converts the analog signal output from the strain sensor operating circuit 55 into a digital signal for output. / D conversion circuit 56, arithmetic processing for calculating the compression distortion amount of the divided plate 20a from the output signal of the A / D conversion circuit 56, and performing data read / write processing to the storage medium 60 such as CF (Compact Flash) An input operation circuit such as a circuit (MPU: Micro Processing Unit) 57, a display circuit 58 having a liquid crystal display or the like for displaying data calculated by the arithmetic processing circuit 57, a keyboard for setting processing contents by the arithmetic processing circuit 57, etc. 59, a storage medium 60 for storing input data from the input operation circuit 59 and processing data by the arithmetic processing circuit 57.

  As shown in FIG. 7, the board box 51 is attached to the inner surface of an oil cap 61 detachably provided on the anchor plate 14 with screws or the like so as to cover the upper end portion of the anchor cable 11.

  When measuring the tension of the ground anchor 10, the waterproof connector cap (not shown) is removed from the oil cap (resin or aluminum) 61 and the tension monitor 52 is connected to the connector 62. Just measure tension.

<Calibration process of tension detector>
As shown in FIG. 1, the tension detecting device 1 is calibrated by applying a tensile force to the anchor cable 11 along the longitudinal direction, thereby applying a pressing force (hereinafter referred to as the sensor plate 20) via the anchor head 13. Load) and the distortion generated in the sensor plate 20 is obtained.

  In the present embodiment, a tensile force is applied to the anchor cable 11 by applying a force in a direction away from the anchor plate 14 to the anchor head 13.

  Further, in the present embodiment, when detecting tension and performing calibration processing, the center hole jack 70 is used to apply a force in a direction away from the anchor plate 14 to the sensor plate 20 using the center hole jack 70. By changing the applied load, the relationship between the load and strain is detected. The center hole jack 70 can directly lift the anchor head 13 fixed to the anchor cable 11.

  That is, the center hole jack 70 is placed in the ram chair 71, which is placed on the anchor head 13 and installed on the concrete surface 12 a, the hydraulic jack 74 provided on the upper surface of the ram chair 71, and the ram chair 71. A yoke-shaped attachment 72 that is attached to the hydraulic jack 74 and holds the anchor head 13 and a hydraulic pump 75 that supplies hydraulic pressure to the hydraulic jack 74 are also provided.

  The ram chair 71 is formed in a cylindrical shape, and its lower end is opened. In addition, an opening 71 b having an appropriate size is provided on the side surface of the lower end portion of the ram chair 71.

  A plurality of position adjusting bolts 76 are screwed into the side surface of the lower end portion of the ram chair 71 at an appropriate interval from each other at a position excluding the opening 71b. These position adjusting bolts 76 are orthogonal to the center line of the ram chair and are mounted at substantially the same height as the anchor plate 14.

  By adjusting the screwing length of these position adjusting bolts 76, the relative position of the ram chair 71 with respect to the anchor plate 14 can be adjusted. In the present embodiment, the position adjustment bolt 76 is adjusted so that the center of the anchor head 13 coincides with the center of the anchor plate 14.

  The ram chair 71 is provided with a recess 71 a into which the fitting portion 74 a of the hydraulic jack 74 is fitted. The center of the ram chair 71 and the center of the hydraulic jack 74 can be aligned by fitting the fitting portion 74a of the hydraulic jack 74 into the recess 71a.

  Calibration processing (hereinafter referred to as calibration) of the tension detecting device 1 is performed after the sensor plate 20 of the tension detecting device 1 is attached and before detecting the tension of the anchor cable 11.

  The relationship between the load acting on the sensor plate 20 based on the tension force of the anchor cable 11 and the compressive strain generated on the sensor plate 20 depends on the unevenness in the contact portion of the anchor head 13 and the anchor plate 14 with the sensor plate 20, concrete It differs for each ground anchor 10 due to the inclination or unevenness of the surface 12a.

  That is, if the installation location of the ground anchor 10 changes, even if the tension force of the anchor cable 11 is the same, the load acting on the sensor plate 20 and the amount of compressive strain generated on the sensor plate 20 change.

  For this reason, in this embodiment, after attaching the tension detecting device 1 of the ground anchor to the ground anchor 10 as described above, calibration is performed before measuring the tension. Thereby, the relationship between the load acting on the sensor plate 20 and the strain is grasped.

  For calibration, first, the tension monitor 52 is connected to the board box 51.

  A pressure gauge 77 for measuring the hydraulic pressure is attached to the pipe between the hydraulic pump 75 and the hydraulic jack 74. Further, a displacement meter 78 for measuring the stroke amount X in the stroke portion 74 a of the hydraulic jack 74 and an amplifier 79 for amplifying the output of the displacement meter 78 are attached.

  The outputs of the pressure gauge 77 and the displacement gauge 78 are input to the tension monitoring device 52 via the amplifier 79.

  Next, a tensile force is applied to the anchor cable 11 by applying a force in a direction away from the sensor plate 20 to the anchor head 13 by the hydraulic jack 74 (hereinafter referred to as jack load). Then, the jack load FJ of the hydraulic jack 74 and the displacement X of the stroke portion 74a in the hydraulic jack 74 are measured. The jack weight FJ is calculated based on the hydraulic pressure supplied to the hydraulic jack 74.

  FIGS. 8A and 8B show a load acting on each portion when a tensile force is applied to the anchor cable 11 by applying a jack load FJ to the anchor head 13 in the longitudinal direction of the anchor cable 11 with the hydraulic jack 74. Indicates.

  As shown in FIG. 8A, when the anchor head 13 is separated from the sensor plate 20, no load is applied to the sensor plate 20, so that compressive strain does not occur. In this case, the jack load FJ is equal to the tension (cable load FC) of the anchor cable 11.

  As shown in FIG. 8B, when the anchor head 13 is in contact with the sensor plate 20, a sensor plate load FS that is a pressing force obtained by subtracting the jack load FJ from the cable load FC is applied to the sensor plate 20.

  Here, the cable load FC when the jack load FJ is 0 is referred to as a set load FB. That is, normally, the set load FB works on each part.

  FIG. 9 shows the balance of each load when the jack load FJ is gradually increased. 10 and 11 show the state of each part and the balance of force at each time point t0 to t6 in FIG.

  As shown in FIG. 9, when the jack load FJ is gradually increased from zero, the jack load FJ becomes equal to the set load FB of the anchor cable 11 at a certain time t2.

  When the jack load FJ is further increased, the anchor cable 11 is extended, and a gap is formed between the anchor head 13 and the sensor plate 20.

  Next, when the jack load FJ is gradually lowered, the anchor cable 11 contracts and the anchor head 13 moves in a direction approaching the sensor plate 20.

  At a certain time t4, the anchor head 13 comes into contact with the sensor plate 20, and the movement of the anchor head 13 stops. Thereby, contraction of the anchor cable 11 stops.

  As the jack load FJ is further lowered, a load (hereinafter referred to as a sensor plate load FS) obtained by subtracting the jack load FJ from the set load FB is applied to the sensor plate 20.

Thus, the sensor plate load FS can be changed by raising or lowering the jack load FJ. When the sensor plate load FS changes, the amount of compressive strain generated in the sensor plate 20 also changes.

  Therefore, by raising or lowering the jack load FJ, the relationship between the sensor plate load FS and the amount of compressive strain of the sensor plate 20 can be obtained.

  The set load (tensile force) FB can be obtained from the relationship between the jack load FJ and the displacement amount X of the stroke portion 74a in the hydraulic jack 74, as will be described next.

  FIG. 12 is an FJ / X-ray diagram showing a relationship between the jack load FJ and the displacement amount X of the stroke portion 74a when the anchor head 13 is moved away from the sensor plate 20 and then the jack load FJ is gradually lowered. is there.

  As can be seen from this FJ / X-ray diagram, when the jack load FJ is lowered, the anchor cable 11 contracts from the stretched state, so the displacement of the stroke portion 74a increases and the gradient of the FJ / X-ray diagram increases. .

  Then, after the anchor head 13 comes into contact with the sensor plate 20, the anchor cable 11 hardly contracts. For this reason, the displacement amount X is the amount of deformation of the sensor plate 20, the anchor head 13, etc., and the gradient of the FJ · X diagram is reduced.

  An inflection point P at which the gradient changes greatly is formed on the FJ · X-ray diagram. The jack load FJ at the inflection point P is the set load FB.

  FIG. 13 shows calibration data indicating the relationship between the sensor plate load FS and the strain ε of the sensor plate 20. In FIG. 13, the horizontal axis indicates the sensor plate load FS, and the vertical axis indicates the strain ε.

  In FIG. 13, circles indicate measurement data, solid lines indicate FS conversion lines A created by generalizing measurement data, and broken lines indicate FS conversion lines B in a range where measurement data cannot be acquired.

  The FS conversion line B is obtained by extending the FS conversion line A upward by a predetermined process. In other words, since the load FS of the sensor plate 20 cannot be made higher than the set load FB by the hydraulic jack 74, in this embodiment, the FS conversion is performed using the gradient (Δε / ΔFS) around the set load FB on the FS conversion line A. An FS conversion line B is created by extending the line A upward.

  In addition, the data of the set load FB in the FS conversion line A can be analyzed, and the FS conversion line B can be generated by a higher order function.

  This calibration data is obtained by raising and lowering the jack load FJ within the range of the set load FB or less.

  When detecting the tension of the ground anchor 10, the compression strain ε of the sensor plate 20 is detected by changing the jack load FJ using the center hole jack 70.

  Next, the FS conversion lines A and B of the calibration data are collated, and a sensor plate load FS corresponding to the detected compression strain ε is obtained. Based on the sensor plate load FS, the tension force of the anchor cable 11 is calculated.

  Hysteresis may occur between the strain ε when the sensor plate load FS increases and the strain ε when it decreases.

  When hysteresis occurs in this way, it is preferable to detect the strain ε both when the sensor plate load FS increases and when the sensor plate load FS decreases and to obtain the FS conversion lines A and B from both data.

  For example, when compressive strain of the sensor plate 20 is detected, hysteresis hardly occurs as shown in FIG.

  On the other hand, as shown in FIG. 15, when detecting the bending distortion of the sensor plate, hysteresis occurs. This is presumably due to slippage between the sensor plate and the anchor head.

  In addition, when one or both of the anchor head 13 and the anchor plate 14 sandwiching the sensor plate 20 have surface irregularities or crushing, the contact state between the sensor plate 20 and the anchor head 13 or the anchor plate 14 becomes uneven. The sensor plate load FS may become unstable.

  In this case, the contact state between the sensor plate 20 and the anchor head 13 or the anchor plate 14 can be adjusted by raising and lowering the hydraulic jack 74 to increase or decrease the jack load FJ.

  As shown in FIG. 1, the hydraulic pressure P supplied to the hydraulic jack 74 (or the jack load FJ calculated from the hydraulic pressure P), the displacement amount X of the stroke portion 74a in the hydraulic jack 74, and the strain ε of the sensor plate 20 are as follows: It is automatically input to the tension monitor 52.

  The tension monitor 52 creates FS conversion lines A and B of calibration data from the input data by a calculation program.

  FIG. 16 shows the calibration logic (see the right column in FIG. 16). At the time of calibration, basic information is set first. Here, ground anchor information and ID input, jack pressure receiving area AJ input, calibration sampling setting information input, and the like are performed.

  Next, a set load FB is obtained. Here, the jack hydraulic pressure P and the displacement amount X are automatically read to calculate the jack load FJ, and the set load FB is calculated from the FJ · X diagram.

  Next, calibration data is collected. Here, when the start button is pressed, the jack oil pressure P and the strain ε are automatically read, and the jack load FJ is calculated. Next, the sensor load FS is calculated.

  The calculation of the sensor load FS is repeatedly performed from the reading of the jack hydraulic pressure P and the strain ε. Then, when the end button is pressed, the above repetitive processing ends.

  Next, error determination of the strain ε data is performed. In the present embodiment, when each strain ε / maximum strain ε <0.2, the strain ε is determined to be an error.

Next, a calibration calculation formula FS (ε) is created. Here, based on the collected data of the sensor plate load FS and the strain ε, a calibration calculation formula FS (ε) or a map is created.

  As described above, according to the present invention, before the tension force of the ground anchor 10 is measured, by applying the jack load FJ to the anchor head 13, a tensile force is applied to the anchor cable 11, and the sensor plate load FS and the sensor plate are applied. Since the relationship with the strain ε generated at 20 is obtained and the FS conversion lines A and B are created based on this relationship, the calibration process can be performed appropriately.

  In addition, since the strain ε generated in the sensor plate 20 can be performed using the strain sensor 21 provided in the sensor plate 20 in order to detect tension, a scaffold or the like can be used without using special equipment. The calibration process can be easily performed even in a place where the condition is poor.

<Second Embodiment>
As shown in FIG. 17, there are cases where a measuring instrument such as a pressure gauge 77 cannot be connected to the tension monitor 52 depending on the installation location of the ground anchor 10.

  In such a case, the FS conversion lines A and B can be created by manually inputting the hydraulic pressure P, the displacement amount X, and the jack load FJ into the tension monitor 52.

  The calibration logic in this case is shown in the center column of FIG. In addition, except the matter demonstrated below, it is the same as that of 1st Embodiment.

  Here, ground anchor information and ID, jack pressure receiving area AJ input, and calibration sampling setting information are manually input as basic information settings.

  In the calculation of the set load FB, the jack hydraulic pressure P and the displacement amount X are manually input to the recorder 80, the set load FB is obtained from the FJ / X-ray diagram, and this is manually input to the recorder 80.

  In the collection of calibration data, when the jack pressure P is manually input to the tension monitor 52 and the read button is pressed, the strain ε is automatically read.

<Third Embodiment>
The tension measurement of the ground anchor 10 may be mainly aimed at managing whether there is anything that is extremely loose or has an abnormally high load, rather than accurately measuring the tension. Many. In this case, performance including workability and cost is required rather than measurement accuracy.

  When simplifying the calibration work, as shown in FIG. 18, the jack load FJ is raised and lowered to detect the set load FB. Next, the strain ε at the set load FB is detected.

  Next, as shown in FIG. 19, the FS conversion line is created by connecting the measurement data of the set load FB and the strain ε and the origin with a straight line.

  In this case, since the strain ε of the sensor plate 20 only needs to be measured at one point where the set load FB acts, the number of work steps can be reduced.

<Fourth embodiment>
As shown in FIGS. 20A and 20B, when the anchor plate 14 has a concave portion 66 or a convex portion 67 on the surface, the contact state between the anchor plate 14 and the sensor plate 20 becomes non-uniform, and the contact is made. Pressure is too high or too low. This is the same when the surface of the anchor head 13 is uneven.

  If the contact pressure between the anchor plate 14 and the sensor plate 20 is too small, the sensor plate 20 may not be distorted, or the sensitivity of the strain sensor 21 may be reduced, making it impossible to detect the distortion.

  In addition, when the contact pressure is excessive, the compressive strain of the sensor plate 20 exceeds the measurement range of the strain sensor 21, and the strain sensor 21 may be damaged in some cases.

  In the present embodiment, data when the contact pressure between the sensor plate 20 and the anchor head 13 or the anchor plate 14 is too low and abnormal data when it is too high are excluded by the following method.

  First, an appropriate range of contact pressure is set. Here, the minimum value of the appropriate range is the first predetermined value, and the maximum value of the appropriate range is the second predetermined value.

  When the contact pressure is less than the first predetermined value, the maximum strain ε is extracted from the strains ε detected by the plurality of strain sensors 21 after the calibration work is completed or during the calibration work.

  Then, a strain ε having a ratio of each strain ε to the maximum strain ε is excluded from a predetermined value, for example, 20% or less. In addition, when there is an excluded strain ε, a warning can be displayed on the tension monitor 52 or an alarm can be sounded.

  Thereby, for example, when the operator removes the sensor plate 20 and sets it again, the contact state between the sensor plate 20 and the anchor head 13 or the anchor plate 14 can be improved, and the calibration can be performed again. As a result, all the strain sensors 21 can be operated in a normal state.

  When the contact pressure exceeds the second predetermined value, the strain ε detected by the strain sensor 21 that exceeds the required range is excluded.

  If the strain ε exceeds the required range during the calibration operation, a warning can be immediately displayed on the tension monitor 52 or an alarm can be sounded.

  Thereby, an operator can recognize a warning or an alarm, for example, by performing an appropriate process such as preventing the sensor plate 20 from being subjected to a further load, and preventing the strain sensor 21 from being damaged.

  The warning or alarm can be generated not only when the strain ε exceeds the required range but also when the strain ε exceeds a predetermined value.

  Further, even when the output signal of the strain sensor 21 becomes excessively low or excessive due to disconnection or deterioration of the electric wires in each part, it can be processed in the same manner as when the contact state is not uniform.

<Fifth embodiment>
As shown in FIG. 21, the inclination of the concrete surface 12a is changed by the fluctuation of the ground 15 or the concrete 12, and the tension of the ground anchor 10 is increased or decreased.

  In such a case, the load distribution acting on the sensor plate 20 changes, and the strain ε detected by each strain sensor 21 with respect to the actual tension may be excessive or small.

  When the load distribution acting on the sensor plate 20 changes, it is preferable to evaluate the tension based on the load applied to the entire sensor plate 20. For this purpose, it is effective to obtain the tension based on the average value of the strains ε by all the strain sensors 21.

  FIG. 22 is a flowchart showing tension calculation processing by the tension monitor 52. Here, first, the strain detected by the strain sensor is read (S1). Next, abnormal distortion is eliminated (S2). Next, an average value of effective distortion is calculated (S3). Subsequently, tension is calculated based on the average value of strain (S4).

In the above-described embodiment, the case where the tension measuring device 1 is already installed on the ground anchor 10 has been described. However, the present invention is also applicable to the case where the tension detecting device 1 is newly installed on the ground anchor 10. it can.

  In this case, a tensile force is applied to the anchor cable 11 to provide a predetermined gap between the anchor head 13 and the anchor plate 14, and the sensor plate 20 is inserted into the gap to reduce the tensile force applied to the anchor cable 11. Then, the relationship between the tensile force and strain ε at that time is obtained.

  Moreover, although the said embodiment demonstrated the case where the calibration process of the tension | tensile_strength detection apparatus 1 which detects the compressive distortion of the sensor plate 20 was demonstrated, this invention is a tension | tensile_strength detection apparatus which detects the bending distortion of the plate for distortion detection. It can also be applied.

It is a figure explaining the calibration process of the tension | tensile_strength detection apparatus of the ground anchor of 1st Embodiment which concerns on this invention. It is a figure which shows the sensor plate of 1st Embodiment which concerns on this invention. It is sectional drawing of the sensor plate of 1st Embodiment which concerns on this invention, and is AA sectional drawing of FIG. It is sectional drawing which shows the attachment state of the distortion sensor of 1st Embodiment which concerns on this invention. It is a figure which shows arrangement | positioning of the sensor plate of 1st Embodiment which concerns on this invention, and is BB sectional drawing of FIG. It is a figure which shows the control part of 1st Embodiment which concerns on this invention. It is sectional drawing which shows the attachment state of the board | substrate box in the control part of 1st Embodiment which concerns on this invention. FIG. 8A is a view showing each load when the anchor head according to the first embodiment of the present invention is separated from the sensor plate, and FIG. 8B is a case where the anchor head is in contact with the sensor plate. It is a figure which shows each load. It is a figure which shows the balance state of each load at the time of raising / lowering the jack load of 1st Embodiment which concerns on this invention. It is a figure which shows the state of each part at the time of raising and lowering the jack load of 1st Embodiment which concerns on this invention, and the balance state of force, and is a figure which shows the state and balance in each time t0-t4 of FIG. It is a figure which shows the state and balance state of each part at the time of raising / lowering the jack load of 1st Embodiment which concerns on this invention, and is a figure which shows the state and balance in each time t4-t6 of FIG. It is a figure which shows the relationship between the jack load of 1st Embodiment which concerns on this invention, and the displacement of a stroke part. It is a figure which shows the relationship between the sensor plate load of 1st Embodiment which concerns on this invention, and distortion. It is a figure which shows the relationship between the sensor plate load of 1st Embodiment which concerns on this invention, and compressive strain. It is a figure which shows the relationship between a general sensor plate load and bending distortion. It is a figure explaining the logic of the calibration of 1st Embodiment and 2nd Embodiment which concern on this invention. It is a figure explaining the calibration process of 2nd Embodiment which concerns on this invention. It is a figure explaining the method of calculating | requiring the set load FB of 3rd Embodiment which concerns on this invention. It is a figure which shows the relationship between the sensor plate load of 3rd Embodiment which concerns on this invention, and distortion. FIG. 20A is a diagram showing a contact state between the sensor plate of the fourth embodiment according to the present invention and an anchor plate having a concave portion, and FIG. 20B is a contact state between the sensor plate and the anchor plate having a convex portion. FIG. It is a figure showing the state where the concrete surface of a 5th embodiment concerning the present invention changed. It is a flowchart which shows the average value calculation process of the distortion of 5th Embodiment which concerns on this invention. It is a figure which shows a general ground anchor. It is sectional drawing which shows the tension | tensile_strength detection method of the ground anchor which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tensile-force detection apparatus 10 Ground anchor 11 Anchor cable 11a Upper end part 11d Circumference 12 Concrete 12a Concrete surface 13 Anchor head 13a Wire material penetration hole 13b Outer periphery 14 Anchor plate 14 Anchor head 15 Ground 20 Sensor plate (Strain detection plate)
20a Dividing plate 20b Hole 20c Inner surface 21 Strain sensor 22 Electric wire 23 Connecting member 24 Electric wire 30 Anchor body 31 Sheath 50 Control unit 51 Substrate box 52 Tensile force monitor device 53 Parallel circuit 54 Storage medium 55 Sensor operating circuit 55 Strain sensor operating circuit 56 Conversion Circuit 57 Arithmetic processing circuit 58 Display circuit 59 Input operation circuit 60 Storage medium 61 Oil cap 66 Concave part 67 Convex part 70 Center hole jack 71 Ram chair 71a Concave part 71b Opening part 72 Attachment 74 Hydraulic jack 74a Stroke part 74a Fitting part 75 Hydraulic pump 76 Position adjustment bolt 77 Pressure gauge 78 Displacement gauge 79 Amplifier 80 Recorder 100 Ground anchor 101 Concrete member 102 Anchor plate 104 Sheath 106 Anchor Cable 108 Anchor head 110 Ground anchor tension detection system 123 Anchor cable 131 Concrete 133 Anchor plate 135 Anchor head 141 Sensor 144 Tension monitor

Claims (11)

A calibration method for performing a calibration process of a tension detecting device that detects a tension of a ground anchor that applies a pressing force to the ground to a laying member laid on the ground,
The ground anchor is disposed through the laying member, a lower end is embedded in the ground, and an upper end projects from the laying member, and an upper end of the tension member. Having a fixed anchor head and an anchor plate disposed between the anchor head and the laying member;
The tension detection device has a strain detection plate disposed between the anchor head and the laying member, and a strain detection means for detecting strain generated in the strain detection plate,
In the calibration process, a tension force is applied to the tension member along the longitudinal direction thereof to change the tension force, and a pressing force acting on the strain detection plate from the tension member via the anchor head; A method for calibrating a tension detecting device, characterized by detecting a relationship with strain generated in a strain detecting plate.   The method for calibrating a tension detecting apparatus according to claim 1, wherein the strain is a compressive strain or a bending strain. The tension detecting device is provided with a plurality of strain detecting means,
The calibration processing calculates an average value of the distortions excluding the distortions out of a predetermined range among the distortions detected by the plurality of distortion detection units, and calculates the average value of the distortions and the pressing force. 3. The method for calibrating a tension detecting device according to claim 1, wherein the relationship is obtained.   4. The tension measuring device according to claim 1, wherein a relationship between the pressing force and the strain is obtained both when increasing and decreasing a tensile force applied to the tension member. 5. Calibration method.   5. The method for calibrating a tension detecting device according to claim 1, wherein a relationship between the pressing force and the strain is obtained after the anchor head collides with the strain detecting plate. 6.   6. The tension detecting device according to claim 1, wherein a relationship between the pressing force and the strain is obtained by changing a tensile force applied to the tension member within a range of a predetermined value or less. Calibration method. Applying the tensile force to the tension member until the anchor head is separated from the strain detection plate,
Find the inflection point in the relationship between the tensile force and the amount of elongation of the tension member,
The tensile force at the inflection point is applied to the tension member to detect distortion of the strain detection plate,
Obtaining a relationship between the tensile force and the strain based on a straight line connecting the point indicating the relationship between the tensile force and the strain at the inflection point, and the origin of the tensile force and the strain. A method for calibrating a tension detecting device according to any one of claims 1 to 6.   A tensile force is applied to the tension member to provide a predetermined gap between the anchor head and the laying member, and the strain detection plate is inserted into the gap to lower the tensile force applied to the tension member. 7. The method for calibrating a tension detecting device according to claim 1, wherein a relationship between the tensile force and the strain at that time is obtained.   9. The relationship between the tensile force and the strain is obtained by excluding the strain out of a predetermined range from the strain detected by the plurality of strain detection means. A method for calibrating a tension detecting device according to claim 1.   10. The method for calibrating a tension detecting device according to claim 9, wherein an alarm or a warning is generated when the distortion is out of the predetermined range.   The tension detecting device according to any one of claims 3 to 10, wherein a relationship between the tensile force and the strain is obtained based on an average value of the strain detected by the plurality of strain detecting means. Calibration method.

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