JP6021254B2 - Ground deformation detection structure, ground deformation detection method, and ground deformation detection device - Google Patents

Description

  The present invention relates to a natural ground deformation detection structure, a natural ground deformation detection method, and a natural ground deformation detection method that are used, for example, when detecting natural ground deformation of a tunnel during excavation by measuring axial force of a rock bolt. It relates to equipment.

  Conventionally, a technique for measuring the axial force of a rock bolt is known as a means for detecting the state of a natural ground during excavation. However, since it is necessary to place a special measuring bolt to measure the shaft of the lock bolt in the ground, it is easy to estimate the lock bolt axial force by measuring the load generated on the washer even with a normal lock bolt. However, a method for detecting ground deformation at an early stage has been proposed. That is, when the natural ground is loosened by excavation, an axial force is generated on the lock bolt, and a load acts on the washer tightened by the nut. Therefore, it is possible to detect ground deformation by measuring the load acting on the washer.

  As a measurement structure used for detecting this kind of ground deformation, for example, an inner washer, an annular measurement disk (load cell), and an outer washer are sequentially inserted and inserted into a protruding portion of an anchor material such as a lock bolt protruding from a drilling hole. Tighten the nut from the top and apply a pulling force to the lock bolt. At the same time, the measurement disk is clamped between the ground and the load pressure is measured by the measurement disk, and the display structure provided on the measurement disk indicates the fixing force. It can be applied (see Patent Document 1).

JP 2001-133392 A

  By the way, the measurement structure as described above may be used, for example, to continue the anchoring force measurement of the anchor material while being installed on the slope of the natural ground. In some cases, after measurement, the measurement structure is disassembled, an expensive measurement disk is removed, and the measurement structure of another anchor material is formed with the removed measurement disk.

  For example, in tunnel construction, after the excavation, spray concrete is applied to the inner surface of the tunnel, and rock bolts are placed on the ground, and then it is confirmed that the natural ground deformation has settled at the rear of a predetermined distance from the face that has advanced by excavation. After that, lining concrete is placed so that the protruding part of the lock bolt is embedded, but at this time, the measurement structure installed on the lock bolt is disassembled and the measurement disk is removed so that it is not embedded in the lining concrete and removed. The measurement structure is formed on another lock bolt near the face using the measured disk (see FIG. 6).

  However, in order to disassemble such a measurement structure and remove the measurement disk from the lock bolt, it is necessary to loosen and remove the nut. However, when the nut is loosened, the stress in the ground is released and the ground is loosened. End up. In addition, since the washer that is actually loaded is released together with the measurement disk, there is a risk of work due to the washer dropping off.

  The present invention is proposed in view of the above problems, and when removing the measuring unit from the lock bolt, the looseness of the natural ground is reduced as much as possible, and the risk that the washer actually supporting the load may fall off. It is an object of the present invention to provide a natural ground deformation detection structure, a natural ground deformation detection method, and a natural ground deformation detection device capable of ensuring safety of work.

The natural ground deformation detection structure of the present invention includes a washer that is externally inserted into a protruding portion of the rock bolt from the natural ground, and a string wound around an outer circumferential groove, and a male thread portion of the protruding portion that is in non-contact with the washer. a slotted nut is screwed into the provided contact from the projecting end side of the lock bolt to the washer, with the grooved nut in the shaft hole is loosely inserted, communicates said outward from said shaft hole and a housing slits cut through the thickness direction is provided on the side, and the lock bolt axial force measuring portion to be extrapolated to the external thread portion in contact with the housing, screwed into the male screw portion is provided with a measuring nut for supporting said lock bolt axial force measuring unit and the abutment and the housing of the housing abutting the washer, wherein the cord of the grooved nut with lead free state slits The grooved nut can be screwed in and brought into contact with the washer according to the drawing of the string, and the grooved nut is in contact with the washer. The measurement nut, the lock bolt axial force measurement unit, and the housing can be detached in accordance with the loosening of the measurement nut.
According to this configuration, when removing the lock bolt axial force measuring unit from the lock bolt, the grooved nut can be removed from contact with the washer, and the load can be removed while maintaining the load supported by the washer. Mountain loosening can be reduced as much as possible. Further, it is possible to eliminate the risk that the washer that actually supports the load will fall off, and to ensure the safety of the work. Further, since the members necessary for the continuous support of the natural ground load are the grooved nut and the housing, it can be realized at a low cost. Further, by screwing the grooved nut by pulling the string which is derived from the slit, it is possible to abut the slotted nut in the housing washers, and shall not need thereof work with easy effort be able to. In addition, by forming the communication portion of the housing as a slit, it is possible to provide a high-strength housing that is substantially provided around the lock bolt over the entire length of the housing in the lock bolt axial direction, and it is possible to increase the strength of the detection structure. .

The ground deformation detection method of the present invention includes a first step of extrapolating a washer to a protruding portion of the rock bolt from the ground, and a groove in which a string is wound around an outer peripheral groove on the male screw portion of the protruding portion. with the attached nut screwed so as not to contact with the washer, a housing slits cut throughout communicating with and thickness direction to the outside from the shaft hole is provided laterally the grooved nut and arranged to be loosely inserted into said shaft hole, wherein a second step of deriving said cord from said slit, and a third step extrapolate lock bolt axial force measuring unit to the external thread portion, the measurement nut A fourth step in which the washer, the housing, and the lock bolt axial force measurement unit are in contact with each other by the measurement nut, and the lock bolt axial force measurement unit locks the lock. Bolt A fifth step of measuring force, a sixth step of pulling the string and screwing the grooved nut into contact with the washer, loosening the screwing of the measurement nut, It is characterized by comprising a measuring nut, the lock bolt axial force measuring part, and a seventh step of detaching the housing.
According to this configuration, when removing the lock bolt axial force measuring unit from the lock bolt, the grooved nut can be removed from contact with the washer, and the load can be removed while maintaining the load supported by the washer. Mountain loosening can be reduced as much as possible. Further, it is possible to eliminate the risk that the washer that actually supports the load will fall off, and to ensure the safety of the work. Further, since the members necessary for the continuous support of the natural ground load are the grooved nut and the housing, it can be realized at a low cost. Further, by screwing the grooved nut by pulling the string which is derived from the slit, it is possible to abut the slotted nut in the housing washers, and shall not need thereof work with easy effort be able to. In addition, by forming the communication portion of the housing as a slit, it is possible to provide a high-strength housing that is substantially provided around the lock bolt over the entire length of the housing in the lock bolt axial direction, and it is possible to increase the strength of the detection structure. .

The ground deformation detection device of the present invention is a ground deformation detection device used in the ground deformation detection structure of the present invention, and is composed of the grooved nut and the housing. Features.

  According to the present invention, when removing the measuring unit from the lock bolt, it is possible to reduce the looseness of the natural ground as much as possible, to reliably avoid the risk of the natural ground collapse, and to actually support the load. This eliminates the risk of the washer falling off and ensures work safety.

The longitudinal cross-sectional view which shows the natural ground deformation detection structure of 1st Embodiment. Explanatory drawing which shows the structural member in the natural ground deformation detection structure of 1st Embodiment. (A) is a side view of a grooved nut, (b) is the front view. (A)-(d) is sectional explanatory drawing which shows the process from placement of the lock bolt to installation of the housing in the natural ground deformation detection method of 1st Embodiment. (A)-(d) is sectional explanatory drawing which shows the process from installation of a measurement disk to the removal of a measurement disk in the natural ground deformation | transformation detection method of 1st Embodiment. (A) is a perspective explanatory drawing which shows the tunnel by which the lock bolt was driven in the internal peripheral surface, (b) is an enlarged view of the A section of the same figure (a). The longitudinal cross-sectional view which shows the natural ground deformation detection structure of 2nd Embodiment. Explanatory perspective drawing which shows the structural member in the natural ground deformation detection structure of 2nd Embodiment.

[First Embodiment Natural Ground Deformation Detection Structure and Natural Deformation Detection Method]
The natural ground deformation detection structure according to the first embodiment of the present invention is installed at a protruding portion of a rock bolt provided on the natural ground. For example, the rock bolt 10 placed in the tunnel space S shown in FIG. It is installed on the protruding part. FIG. 6 shows a state in which the ground deformation detection structure is disassembled and a measurement disk 14 or the like, which will be described later, is removed, and the lock placed in the drill hole 4 made in the ground 3 and the shotcrete 2 is shown. A washer 11 and a grooved nut 12 are provided at the projecting portion of the bolt 10, and are supported by the axial force of the lock bolt 10 when the natural ground 3 is loosened, and these are embedded in the lining concrete 6. ing. In FIG. 6, 1 is the inner peripheral surface of the tunnel, 5 is the grout material filled in the gap in the drilling hole 4 into which the lock bolt 10 is inserted, and 7 is positioned in front of the tunnel being excavated. It is a face.

  And the natural ground deformation detection structure of 1st Embodiment is a lock | rock in which the external thread part 10a is formed in the base end part, for example, as shown in FIG.1 and FIG.2, and the screw node 10b is formed in the front end side. Installed on the projecting portion of the bolt 10, has a washer 11, a nut 12 with a groove as a nut, and a housing 13, and is further extrapolated to the male screw portion 10 a so as to contact the housing 13 from the projecting end side of the lock bolt 10. The measurement disk 14 and the plate 15 that constitute the lock bolt axial force measurement unit, and the measurement nut 16 are provided.

  The washer 11 is provided so as to be in contact with the shotcrete 2 by being externally inserted into a protruding portion of the rock bolt 10 from the ground 3 and the shotcrete 2, and in this example, the male screw portion 10a of the bump. As the washer 11, an appropriate one such as a round washer can be used in addition to the square washer shown in the drawing.

  As shown in FIGS. 1 to 3, the grooved nut 12 has one end of the string 122 fixed to a predetermined portion of the outer circumferential groove 121 formed on the outer periphery, the string 122 is wound around the outer circumferential groove 121, and the string 122. The other end is drawn out of the outer peripheral groove 121. The string 122 is wound so that the grooved nut 12 is screwed in the bolt tightening direction when pulled out. The string 122 is preferably a wire such as a stainless steel wire, but any wire or strip may be used as long as it can be wound around the outer circumferential groove 121 and the grooved nut 12 can be screwed. The grooved nut 12 is screwed into the male screw portion 10a at a position away from the washer 11 so as not to contact the washer 11, and is provided so as not to contact a measurement disk 14 described later.

  The housing 13 has a thick plate shape, and has a thickness that allows the grooved nut 12 to move by a predetermined length of the male screw portion 10a. A shaft hole 131 is formed at the center of the housing 13 with a diameter that allows the grooved nut 12 to enter. The shaft hole 131 corresponds to a hollow portion of the housing 13. The housing 13 is formed with a slit 133 that communicates from the shaft hole 131 to the side surface 132 as a communicating portion that communicates from a hollow portion provided on the side to the outside. The slit 133 extends over the entire thickness of the housing 13. It is cut and formed.

  The housing 13 is provided on the outer periphery of the male screw portion 10a so as to come into contact with the washer 11 from the protruding end side of the lock bolt 10, and the shaft hole 131 in which the grooved nut 12 screwed into the male screw portion 10a is a hollow portion. It is arranged so as to be loosely inserted inside. Then, the string 122 of the grooved nut 12 is led out from the slit 133 which is a communication portion, and the other end of the string 122 is pulled out to the outside of the housing 13. In the first embodiment, the communication portion provided on the side of the housing 13 and communicating from the hollow portion to the outside is appropriate as long as the string 122 of the grooved nut 12 can be led out to the outside. A through hole or the like communicating from the shaft hole 131 to the side surface 132 may be used.

  The measuring disk 14 has a ring shape, for example, oil is sealed in two circular plates serving as pressure receiving surfaces, and the pressure applied to the pressure receiving surface is displayed by a display means such as an attached Bourdon tube. And is externally inserted into the male screw portion 10a so as to come into contact with the housing 13 from the protruding end side of the lock bolt 10. Further, the plate 15 constituting the lock bolt axial force measuring unit together with the measuring disk 14 has a shaft hole 151 formed at the center, and the male threaded part 10a is brought into contact with the measuring disk 14 from the protruding end side of the lock bolt 10. Extrapolated to

  The measurement nut 16 is screwed into the male threaded portion 10a of the lock bolt 10, and the plate 15, the measurement disk 14, the housing 13, and the washer 11 are brought into contact with each other, and the washer 11 is brought into contact with the shotcrete 2. Support in a state. The measurement nut 16 supports the plate 15 and the measurement disk 14 at predetermined positions, so that when a load is applied from the natural ground 3, the measurement disk 14 is pressed via the washer 11 and the housing 13 to measure the measurement disk. 14 is loaded, and the axial force of the lock bolt 10 can be easily measured from the pressure measured by the measurement disk 14 and the load.

  Then, the grooved nut 12 is screwed by the screwing operation by pulling the string 122 through the slit 133, whereby the grooved nut 12 is brought into contact with the washer 11, and the measuring nut 16 is loosened in this state. Thus, the load support from the natural ground 3 by the washer 11 is maintained, and the plate 15 and the measurement disk 14 corresponding to the lock bolt axial force measurement unit and the housing 13 are locked without dropping the washer 11. The bolt 10 can be detached from the male thread portion 10a.

  Next, a natural ground deformation detection method using the natural ground deformation detection structure will be described.

  First, as shown in FIG. 4A, for example, a rock bolt 10 is formed by forming a hole 4 in a sprayed concrete 2 applied to a tunnel ground 3 and a tunnel inner peripheral surface 1. 4 is filled with a grout material 5 and solidified, and further, as shown in FIG. 4B, the male screw of the lock bolt 10 protruding from the ground 3 and the shotcrete 2 The washer 11 is extrapolated to the part 10a, and the washer 11 is arranged so as to substantially contact the shotcrete 2.

  Thereafter, as shown in FIG. 4C, the grooved nut 12 is screwed into the male screw portion 10 a of the lock bolt 10, and is screwed to a position separated so as not to contact the washer 11. 4D, the housing 13 is disposed on the outer periphery of the male screw portion 10a so that the grooved nut 12 is loosely inserted into the shaft hole 131 corresponding to the hollow portion of the housing 13. The string 122 of the hooked nut 12 is led out of the housing 13 through a slit 133 corresponding to a communicating portion of the housing 13.

  Thereafter, as shown in FIGS. 5A and 5B, the measurement disk 14 and the plate 15 constituting the lock bolt axial force measurement unit are sequentially extrapolated from the protruding end side of the lock bolt 10 to the male screw portion 10a. The measurement nut 16 is screwed into the male screw portion 10a, and the washer 11, the housing 13, the measurement disk 14, and the plate 15 are supported by the measurement nut 16 in contact with each other. Then, the load applied to the washer 11 by the measuring disk 14 and the axial force of the lock bolt 10 are measured to detect the natural deformation, and this measurement is performed for a necessary period to confirm the natural deformation. .

  Thereafter, when the measuring disk 14 is detached, as shown in FIG. 5 (c), the string 122 of the grooved nut 12 is pulled and the grooved nut 12 is screwed to advance toward the washer 11. The attached nut 12 is brought into contact with the washer 11. Then, in this state, the screwing of the measuring nut 16 is loosened, and the measuring nut 16, the plate 15, the measuring disk 14, and the housing 13 are removed from the male threaded portion 10a of the lock bolt 10 (see FIG. 5D). The removed measurement disk 14, as well as the housing 13, the plate 15, and the measurement nut 16 are used when forming a natural ground deformation detection structure on the lock bolt 10 driven in another position. Further, the measurement nut 16, the plate 15, the measurement disk 14, and the protruding portion of the lock bolt 10 from which the housing 13 is detached, the washer 11 externally attached thereto, and the male screw portion 10a of the protruding portion are screwed together. The grooved nut 12 is embedded in the lining concrete 6 in a subsequent process.

  According to the ground deformation detection structure or the ground deformation detection method of the first embodiment, the grooved nut 12 is brought into contact with the washer 11 when the measuring disk 14, the plate 15, etc. are removed from the lock bolt 10. The load can be removed while maintaining the load support from the natural ground 3 by the washer 11, and the looseness of the natural ground 3 can be reduced as much as possible. Further, it is possible to eliminate the risk that the washer 11 that actually supports the load will drop off, and to ensure the safety of the work. Moreover, since the members required for the continuous support of the natural ground load are the grooved nut 12 and the housing 13, it can be realized at low cost.

  Further, by pulling the string 122 led out from the communicating portion and screwing the grooved nut 12, the grooved nut 12 in the housing 13 is brought into contact with the washer 11 even when the communicating portion is a small slit 133 or the like. In addition, the operation can be simple and labor-saving. Further, since the communication portion can be a small slit 133 or the like, it can be a high-strength housing 13 that is provided substantially around the lock bolt 10 over the entire length of the housing 13 in the lock bolt axial direction. As a result, it is possible to increase the strength of the detection structure.

[A natural ground deformation detection structure and a natural ground deformation detection method of the second embodiment]
Next, a ground deformation detection structure and a ground deformation detection method according to the second embodiment will be described.

  As shown in FIGS. 7 and 8, the ground deformation detection structure of the second embodiment is provided with a nut 22 and a housing 23 at corresponding positions instead of the grooved nut 12 and the housing 13 in the first embodiment, respectively. Other configurations are basically the same as those of the first embodiment.

  The nut 22 is a nut such as a general hexagon nut, and is screwed into the male screw portion 10a at a position spaced from the washer 11 so as not to contact the washer 11, and is also in contact with a substrate 231 or a measurement disk 14 described later. It is provided so as not to.

  The housing 23 has a rectangular substrate 231, and a shaft hole 232 into which the protruding portion of the lock bolt 10 can be inserted is formed at the center of the substrate 231. On one surface of the substrate 231, side walls 233 and 233 are spaced apart from each other at opposite positions, and the side walls 233 are formed to extend from the substrate 231. The side walls 233 and 233 are spaced apart from each other so that the nut 22 can be loosely inserted therebetween, and the side walls 233 and 233 have a height that allows the nut 22 to move by a predetermined length of the male screw portion 10a. The space between the side walls 233 and 233 corresponds to the hollow portion of the housing 23.

  In the housing 23, the open portion between the end edge of one side wall 233 and the end edge of the other side wall 233 corresponds to a communication portion communicating from the hollow portion provided on the side to the outside. A tool such as a wrench can be inserted, and the nut 22 disposed in the hollow portion is formed in a size that can be screwed with the tool. In addition, the communication part in 2nd Embodiment is appropriate if it is the structure which can insert tools, such as a wrench, and can screw the nut 22 arrange | positioned in a hollow part with a tool.

  The housing 23 is provided on the outer periphery of the male screw portion 10a so as to contact the washer 11 from the protruding end side of the lock bolt 10, and the male screw portion 10a is inserted into the shaft hole 232 with the base plate 231 facing the protruding end side of the lock bolt 10. Is provided on the outer periphery so that the tips of the side walls 233 and 233 are in contact with the washer 11. Further, the nut 22 screwed into the male screw portion 10a is disposed so as to be loosely inserted between the side walls 233 and 233 which are hollow portions. A measurement disk 14 constituting a lock bolt axial force measurement unit is in contact with the substrate 231.

  In the natural ground deformation detection structure of the second embodiment, the measurement nut 16 causes the plate 15, the measurement disk 14, the housing 23, and the washer 11 to abut each other, and causes the washer 11 to abut against the shotcrete 2. I support it in the state. Then, by inserting a tool such as a wrench from the open portion which is the communication portion and screwing the nut 22 in, the nut 22 is brought into contact with the washer 11, and in this state, the measuring nut 16 is loosened, and the washer 11 The measurement nut 16, the plate 15 corresponding to the lock bolt axial force measurement unit and the measurement disk 14, and the housing 23 are connected to the male screw of the lock bolt 10 without causing the washer 11 to fall off. It can be detached from the portion 10a.

  In the natural ground deformation detection method using the natural ground deformation detection structure of the second embodiment, after the washer 11 is arranged as in the first embodiment, the nut 22 is screwed into the male thread portion 10a of the lock bolt 10, The housing 23 is arranged on the outer periphery of the male screw portion 10a so that the board 231 is located on the protruding end side of the lock bolt 10 so as not to contact the washer 11, and corresponds to the hollow portion of the housing 23. The nut 22 is loosely inserted in the space between the side walls 233 and 233 to be performed.

  Thereafter, as in the first embodiment, the measurement disk 14 and the plate 15 constituting the lock bolt axial force measurement unit are sequentially extrapolated from the protruding end side of the lock bolt 10 to the male screw portion 10a, and the measurement nut 16 is further inserted into the male screw. The washer 11, the housing 23, the measurement disk 14, and the plate 15 are in contact with each other and supported by the measurement nut 16. Then, the load applied to the washer 11 by the measuring disk 14 and the axial force of the lock bolt 10 are measured to detect the natural deformation, and this measurement is performed for a necessary period to confirm the natural deformation. .

  Thereafter, when the measuring disk 14 is detached, a tool such as a wrench is inserted from an open portion between the edge of one side wall 233 and the edge of the other side wall 233, and the nut 22 is screwed with the tool. The nut 22 is brought into contact with the washer 11. In this state, the screwing of the measurement nut 16 is loosened, and the measurement nut 16, the plate 15, the measurement disk 14, and the housing 23 are removed from the male screw portion 10 a of the lock bolt 10. The removed measurement disk 14, as well as the housing 23, the plate 15, and the measurement nut 16 are used to form a natural ground deformation detection structure on the lock bolt 10 driven in another position. Further, the measurement nut 16, the plate 15, the measurement disk 14, and the protruding portion of the lock bolt 10 from which the housing 23 is detached, the washer 11 externally attached to the protruding portion, and the male screw portion 10a of the protruding portion are screwed together. The nut 22 is embedded in the lining concrete 6 in a later process.

  According to the natural ground deformation detection structure or the natural ground deformation detection method of the second embodiment, a corresponding effect can be obtained by the configuration corresponding to the first embodiment, and an opening corresponding to a communication portion into which a tool can be inserted is provided. By inserting a tool from the portion and screwing the nut 22 in, the nut 22 can be brought into contact with the washer 11 by a simple and trouble-free operation. In addition, since a general nut can be used as the nut 22, further cost reduction can be achieved.

[Modifications of Embodiment, etc.]
In addition to each invention and each embodiment, the invention disclosed in this specification is specified by changing these partial configurations to other configurations disclosed in this specification within the applicable range, or these It includes those specified by adding other configurations disclosed in this specification to the configuration, or those obtained by deleting these partial configurations to the extent that partial effects can be obtained and specifying them as a superordinate concept. The following modifications are also included.

  For example, the lock bolt axial force measuring unit according to the present invention is appropriate in addition to the measuring disk 14 and the plate 15 that enclose the oil of the above embodiment and display the pressure with a Bourdon tube. A predetermined pressure sensor such as a shape is sandwiched between the housings 13 and 23 and the plate 15 or between the housings 13 and 23 and the measurement nut 16, and light-emitting parts such as LEDs are color-coded on the side parts of the pressure sensor. As a configuration that controls the control unit so that the corresponding light emitting unit such as green or red emits light according to the pressure detection value of the pressure sensor, the load applied to the washer and the axial force of the lock bolt can be directly observed It is good also as a thing.

  Further, a special nut or a general nut such as a grooved nut 12 screwed into the male screw portion of the protruding portion of the lock bolt and loosely inserted into the hollow portion of the housing is connected to the communication portion in the present invention via the communication portion. For example, when a nut is screwed in with a hand or a finger, an open portion provided in the housing in a size that allows the hand or the finger to be inserted can be used. Further, the natural ground targeted by the present invention is appropriate in addition to the natural ground around the tunnel being excavated, and the present invention can be used when detecting the natural ground deformation at an appropriate place.

  The present invention can be used, for example, when detecting ground deformation such as a tunnel during excavation.

DESCRIPTION OF SYMBOLS 1 ... Tunnel inner peripheral surface 2 ... Sprayed concrete 3 ... Ground mountain 4 ... Drilling hole 5 ... Grouting material 6 ... Covering concrete 7 ... Face face 10 ... Lock bolt 10a ... Male thread part 10b ... Screw joint 11 ... Washer 12 ... With groove Nut 121 ... outer peripheral groove 122 ... string 13 ... housing 131 ... shaft hole 132 ... side 133 ... slit 14 ... measuring disk 15 ... plate 151 ... shaft hole 16 ... measuring nut 22 ... nut 23 ... housing 231 ... substrate 232 ... shaft hole 233 ... side plate S ... tunnel space

Claims (3)

A washer extrapolated to the protruding part of the rock bolt from the ground,
A string nut is wound around the outer circumferential groove, and a grooved nut that is screwed to the male thread portion of the protruding portion without contact with the washer
Said provided contact from the projecting end side of the lock bolt to the washer, with the grooved nut in the shaft hole is loosely fitted, outright throughout communicating with and thickness direction to the outside from the shaft hole write A housing in which a slit is provided on the side;
A lock bolt axial force measuring portion to be extrapolated to the external thread portion in contact with the housing,
A screw nut that is screwed into the male screw portion, and includes a measurement nut that supports the contact between the lock bolt axial force measurement unit and the housing and the contact between the housing and the washer;
The string of the grooved nut is led out from the slit in a state where it can be pulled out,
According to the drawing of the string, the grooved nut can be screwed into contact with the washer, and the measurement nut is loosened in a state where the grooved nut is in contact with the washer. According to the invention, the measurement nut, the lock bolt axial force measurement unit, and the housing can be detached. A first step of extrapolating a washer to the protruding portion of the rock bolt from the ground;
The male thread portion of the projecting portion, a grooved nut string on an outer peripheral groove is wound with screwed so as not to contact with the washer, outright throughout communicating with and thickness direction to the outside from the shaft hole A second step in which a housing in which a slit inserted therein is provided is arranged so that the grooved nut is loosely inserted into the shaft hole , and the string is led out from the slit ;
A third step of extrapolating the lock bolt axial force measuring portion to the male screw portion;
A fourth step of screwing a measuring nut into the male screw portion and supporting the washer, the housing, and the lock bolt axial force measuring portion in contact with each other by the measuring nut;
A fifth step of measuring an axial force of the lock bolt in the lock bolt axial force measuring unit;
A sixth step of pulling the string and screwing the grooved nut into contact with the washer;
A seventh step of loosening the screwing of the measuring nut and detaching the measuring nut, the lock bolt axial force measuring unit, and the housing;
A natural ground deformation detection method comprising: A ground deformation detection device used in the ground deformation detection structure according to claim 1 ,
A ground deformation detection device comprising the grooved nut and the housing .

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