JPH094397A - Lock bolt measuring method and device for tunnel - Google Patents

Abstract

PURPOSE: To detect the filling state of mortar by driving reference drive bolts near a lock bolt, and comparing the tuning frequencies of the electromagnetic waves applied to both bolts. CONSTITUTION: The first and second reference drive bolts 9, 10 having known lengths are inserted into holes 7, 8 formed near a lock bolt 5 having an unknown length, the void in the hole 7 is completely filled with mortar, and the hole 8 is filled with mortar in the incomplete state. An electromagnetic wave oscillator 11 and a reception level detector 12 are connected to the first reference drive bolt 9, and electromagnetic waves are applied to it while the frequency is changed in sequence. The electromagnetic wave frequency tuned in response to the length of the first reference drive bolt 9 is specified based on the diagram of the electromagnetic wave absorption level tuning frequency obtained this time. The electromagnetic wave oscillator 11 and the reception level detector 12 are connected to the lock bolt 5 having the unknown length, the similar diagram is obtained, the length of the lock bolt 5 is estimated via comparison and calculation in reference to the tuning frequency corresponding to the length of the first reference drive bolt 9, and the filling state of mortar is estimated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel rock bolt measuring method and apparatus, and more particularly to a measuring method and apparatus for measuring the length and the mortar filling state of a rock bolt placed in the ground where a tunnel is formed. It is about.

[0002]

2. Description of the Related Art Generally, in forming a tunnel, there is a step of drilling a predetermined position on an arched wall surface of a tunnel formed by excavation, inserting a lock bolt of a predetermined length, and injecting mortar. In order to confirm whether or not the prescribed lock bolt has been inserted and whether or not the mortar has been completely filled after construction, conventionally, as construction management, check the length of the lock bolt used before construction and after construction. The pull-out inspection is performed to check whether the pull-out has a predetermined adhesion strength.

[0003]

However, the pull-out inspection of the lock bolt has problems in terms of time and cost.

The present invention is designed to eliminate the above drawbacks.

[0005]

A method for measuring a rock bolt of a tunnel according to the present invention comprises a step of driving a reference driving bolt having a known length in the vicinity of the lock bolt driven in the tunnel in the same manner as the lock bolt. , A step of adding a variable frequency electromagnetic wave to the reference mounting bolt and the lock bolt and measuring the tuning frequency from the electromagnetic wave absorption level, and estimating the length of the lock bolt from the difference between the tuning frequencies corresponding to the both bolts. Consists of steps.

Further, in the tunnel rock bolt measuring method according to the present invention, a first reference driving bolt having a known length is driven near the lock bolt driven in the tunnel in the same manner as the lock bolt, and driven. The step of completely filling the hole with mortar, the step of placing a second reference mounting bolt of known length in the same manner as the lock bolt, and the step of incompletely filling the casting hole with mortar; A step of applying a variable frequency electromagnetic wave to the first and second reference mounting bolts and measuring the tuning frequency from the electromagnetic wave absorption level; and the difference between the tuning frequencies corresponding to the bolts to the mounting hole of the lock bolt. And the step of estimating the filling state of the mortar.

Further, the tunnel rock bolt measuring device of the present invention comprises a reference mounting bolt of known length, which is mounted near the lock bolt of the tunnel in the same manner as the above lock bolt,
An electromagnetic wave oscillator for switching and applying a variable frequency electromagnetic wave to the lock bolt and the reference driving bolt, measuring means for measuring the tuning frequency of the electromagnetic wave with respect to the lock bolt and the reference driving bolt, and tuning corresponding to both bolts. And a measuring means for measuring the length of the lock bolt from the frequency difference.

Further, the tunnel rock bolt measuring device of the present invention is a first standard in which the length of the rock bolt of the tunnel is known and the same as the above-described rock bolt is known and the hole is completely filled with mortar. A variable frequency electromagnetic wave is switched and applied to the driving bolt and a second reference driving bolt whose length is known and whose driving hole is incompletely filled with mortar, and the lock bolt and the first and second reference driving bolts. An electromagnetic wave oscillator, a measuring means for measuring the tuning frequency of the electromagnetic wave with respect to the lock bolt and the first and second reference mounting bolts, and the driving of the lock bolt from the difference between the tuning frequencies corresponding to the bolts. And means for estimating the filling state of the mortar into the hole.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is the ground, 2 is a tunnel excavated in the ground 1, 3 is an arched wall surface of the tunnel 2, 4 is a hole drilled in the ground 1 through the arched wall surface 3. Reference numeral 5 indicates a lock bolt of unknown length inserted into the hole 4, and 6 indicates mortar filled in the void in the hole 4.

In the present invention, holes 7 and 8 similar to the hole 4 are formed in the vicinity of the lock bolt 5 of unknown length, and the first reference striking rod having a known length is formed in the holes 7 and 8. The mounting bolt 9 and the second reference mounting bolt 10 of known length are respectively inserted, and the space in the hole 7 into which the first reference mounting bolt 9 is inserted is completely filled with the mortar 6. , Second
The filling of the mortar in the hole 8 into which the standard setting bolt 10 of FIG.

Further, 1 to 50 MH is provided in the tunnel 2.
A variable frequency electromagnetic wave oscillator 11 that oscillates an electromagnetic wave having a frequency in the range of z and a reception level detector 12 are arranged.
Output terminal of the electromagnetic wave oscillator 11 and reception level detector 1
The two input terminals can be switched and connected to the respective bolts 5, 9 and 10 via the incident reflection detection detector 13 and the connection terminal 14, respectively.

Since the tunnel lock bolt measuring method and device of the present invention are as described above, when measuring the length of the lock bolt 5 of unknown length, first, the electromagnetic wave oscillator 11 and the reception level detector 12 are set to the above-mentioned first. The reference mounting bolt 9 of No. 1 is switched and connected, and an electromagnetic wave is applied thereto while changing its frequency in sequence.

In this case, since the bolt in the ground 1 functions as a vertical antenna for electromagnetic waves, the electromagnetic wave having a wavelength corresponding to four times the length of the bolt is tuned to the bolt so that the electromagnetic wave absorption level is reduced. Become.

Therefore, the electromagnetic wave absorption level-tuning frequency diagram as shown in FIG. 2 can be obtained on the detection screen in the reception level detector 12, and the first reference mounting bolt 9 can be obtained from this diagram. It is possible to specify the electromagnetic wave frequency to be tuned corresponding to the length from the position where the electromagnetic wave absorption level becomes minimum.

It should be noted that the tuning frequency changes somewhat depending on the conditions around the bolt, but in an ideal environment in which there is no influence of the environment in a vacuum, the tuning frequency for a bolt having a length of 6 m is about 12.5 MHz. It was confirmed.

Next, the electromagnetic wave oscillator 11 and the reception level detector 12 are connected to the lock bolt 5 of unknown length,
A similar diagram is obtained, and from the tuning frequency obtained from this diagram, the length of the first reference mounting bolt 9 having a known length and the corresponding tuning frequency are referred to, and a comparison and arithmetic circuit (not shown) is used. ) Etc., the length of the unknown rock bolt 5 is estimated.

The length of the first reference mounting bolt 9 of which the length is known is 1 with respect to the lock bolt 5 whose length is to be measured.
It is preferable to use the one having a difference within m from the viewpoint of error.

It was also confirmed that the tuning frequency also changes depending on the degree of mortar filling in the holes.

Therefore, although the length of the lock bolt 5 is known, if the filling condition of the mortar 6 into the hole 4 into which the lock bolt 5 is inserted is unknown, the above-mentioned measurement is performed and the mortar is known. The same procedure is performed for the second reference mounting bolt 10 that is not completely filled, and
The mortar filling state in the hole 4 into which the lock bolt 5 is inserted can also be estimated from the relationship between the tuning frequency and the length and the mortar filling state obtained from the reference mounting bolts 9 and 10.

[0021]

As described above, according to the tunnel rock bolt measuring method and apparatus of the present invention, the length of the lock bolt 5 placed in the ground 1 and the mortar filling state in the hole 4 are set after the completion of construction. There is a great benefit of being able to measure very easily and accurately.

[Brief description of drawings]

FIG. 1 is an explanatory view of a tunnel rock bolt measuring method and device according to the present invention.

FIG. 2 is a diagram for explaining a tunnel rock bolt measuring method and device according to the present invention.

[Explanation of symbols]

 1 Ground 2 Tunnel 3 Arched Wall Surface 4 Hole 5 Rock Bolt 6 Mortar 7 Hole 8 Hole 9 First Reference Placing Bolt 10 Second Reference Placing Bolt 11 Electromagnetic Wave Oscillator 12 Reception Level Detector 13 Incident Reflection Detection Detector 14 Connecting terminal

Claims (4)

[Claims] 1. A step of driving a reference mounting bolt of a known length in the vicinity of a lock bolt driven in a tunnel in the same manner as the lock bolt, and a variable frequency electromagnetic wave is applied to the reference driving bolt and the lock bolt. In addition, a method of measuring a rock bolt of a tunnel, which comprises a step of measuring the tuning frequency from the electromagnetic wave absorption level and a step of estimating the length of the lock bolt from the difference between the tuning frequencies corresponding to the both bolts. . 2. A step of placing a first reference placing bolt of known length in the vicinity of a rock bolt placed in a tunnel in the same manner as the lock bolt, and completely filling the placing hole with mortar, A step of placing a second reference placing bolt of known length in the same manner as the lock bolt, and incompletely filling the placing hole with mortar; and the lock bolt and the first and second reference placing bolts. A variable frequency electromagnetic wave, and measuring the tuning frequency from the electromagnetic wave absorption level; and the step of estimating the filling state of the mortar into the mounting hole of the lock bolt from the difference in the tuning frequency corresponding to each bolt. A method for measuring a rock bolt in a tunnel, which is characterized in that 3. A reference placing bolt having a known length placed near the lock bolt of the tunnel in the same manner as the lock bolt, and an electromagnetic wave for selectively applying variable frequency electromagnetic waves to the lock bolt and the reference placing bolt. An oscillator, a measuring means for measuring the tuning frequency of the electromagnetic wave with respect to the lock bolt and the reference mounting bolt, and a measuring means for measuring the length of the lock bolt from the difference between the tuning frequencies corresponding to the both bolts. A rock bolt measuring device for tunnels. 4. A first reference placing bolt having a known length which is placed near a lock bolt of a tunnel in the same manner as the lock bolt and whose placing hole is completely filled with mortar, and a placing bolt whose known length is provided. A second reference mounting bolt whose hole is incompletely filled with mortar, an electromagnetic wave oscillator for selectively applying variable frequency electromagnetic waves to the lock bolt and the first and second reference mounting bolts, the lock bolt, and First and second
Measuring means for measuring the tuning frequency of the electromagnetic wave with respect to the reference mounting bolt, and means for estimating the filling state of the mortar into the mounting hole of the lock bolt from the difference in the tuning frequency corresponding to each bolt. A unique device for measuring rock bolts in tunnels.