JP2023024089A - Tunnel face front survey system, geophone, and tunnel face front survey method - Google Patents

Abstract

To provide a tunnel face front survey system, a geophone, and a tunnel face front survey method capable of increasing analysis accuracy of an elastic wave from the front of a tunnel face by blasting and also facilitating positional change of the geophone.SOLUTION: The tunnel face front survey system comprises an exploder 1 starting blasting for excavation, a detector 2 detecting a shot mark which indicates start timing for the blasting for excavation, and a geophone 3 detecting an elastic wave 8 generated by the blasting for excavation. The geophone 3 is located at a receiving hole 6 drilled in a tunnel peripheral wall surface, and has a holding part for fixing the geophone 3 onto a porous wall of the receiving hole 6.SELECTED DRAWING: Figure 1

Description

The present invention relates to a face forward exploration system, a geophone, and a face forward exploration method.

In the construction of mountain tunnels, it is important to grasp ground information such as fracture zones and spring zones that may cause problems in construction in advance. In order to grasp the rock ground information in advance, face forward prospecting using the principle of reflection seismic survey has been performed. The TSP (Tunnel Seismic Prediction) method and the TFT (Tunnel Face Tester) method are known as conventional methods for face forward exploration. In the TSP method, multiple blasting holes drilled in the tunnel peripheral wall are sequentially blasted to generate vibration, and the reflected waves reflected by the fracture zone are received by geophones in multiple vibration receiving holes and analyzed. This technology predicts the ground conditions ahead. Details of the TSP method are disclosed in Non-Patent Document 1, for example. In addition, in the TFT method, the tunnel face wall is blasted to generate vibration, and the reflected wave reflected by the fracture zone is received by a geophone placed on the rock bolt head of the tunnel wall and analyzed. It is a technology to predict the rock ground condition of Details of the TFT method are disclosed in Patent Document 1, for example.

Katsuhisa Yotsuka, Shigeru Shinohara, Tunnel Face Forward Exploration System TSP303 Prediction of fault fracture zone, geological interface and spring water in front of the face by three-dimensional analysis of elastic wave reflection method, Construction Machinery Construction, Vol.68, No. 5, May 2016

JP 2018-025487 A

In the TSP method, the epicenter is the exploration blast. For this reason, it is necessary to suspend the excavation work during face forward exploration. As a result, there is a problem that the excavation work is prolonged. In addition, in the TSP method, it was necessary to fix the geophone by filling the inside of the receiving hole with a filler such as mortar in order to improve the analysis accuracy of the reflected wave. For this reason, even if bad ground is distributed at the position of the geophone, the position cannot be changed, and it is necessary to re-drill the hole for receiving the geophone, which takes time to install the geophone. I had a problem.
On the other hand, the TFT method has the advantage that the excavation work does not have to be interrupted because the blasting for excavation is used as the epicenter. However, in the TFT method, since the geophone is placed at the top of the rock bolt, the noise of the reflected wave increases due to the influence of the surface wave propagating along the tunnel sidewall, which makes it difficult to improve the analysis accuracy.
From this point of view, the present invention provides a front face exploration system, a geophone, and a front face exploration system that can improve the analysis accuracy of elastic waves from the front of the face due to blasting and facilitate the position change of the geophone. The subject is to propose an exploration method.

In order to solve the above problems, the present invention provides a blaster for starting excavation blasting, a detector for detecting a shot mark indicating the start timing of excavation blasting, and a shot mark generated due to the excavation blasting. a geophone for detecting elastic waves, the geophone being arranged in a vibration receiving hole drilled in the tunnel peripheral wall surface, and a face provided with a holding portion for fixing the geophone to the hole wall of the vibration receiving hole. It is a forward looking system.
Further, the present invention is a geophone for detecting elastic waves generated due to blasting for excavation, which is arranged in a vibration receiving hole drilled in a tunnel wall surface, and the geophone is disposed in the vibration receiving hole. A geophone with a holding part fixed to a hole wall.
Further, the present invention comprises a first step of placing a geophone in a vibration receiving hole drilled in a tunnel wall surface, a second step of fixing the geophone to the hole wall of the vibration receiving hole, and operating a blaster. a third step of starting excavation blasting with a detector; a fourth step of detecting a shot mark indicating the start timing of excavation blasting by a detector; and a fifth step of detecting .
According to this configuration, since the blasting for excavation is the epicenter, the excavation work does not have to be interrupted. In addition, since the geophone is placed in the receiving hole, compared to the TFT method, the elastic waves generated due to the blasting for excavation (including the reflected waves reflected by the fracture zone in front of the face and the seep zone, etc.) ) can be reduced. In addition, since the holding part fixes the geophone to the hole wall of the vibration receiving hole, the sensor of the geophone can be brought into close contact with the ground, and the noise of the elastic wave detected by the sensor can be reduced without filling materials such as mortar. can. Therefore, it is possible to improve the analysis accuracy when the analysis device analyzes the elastic waves detected by the geophone. In addition, since the holding part can release the fixation of the geophone to the hole wall of the receiving hole, even if a defective ground is distributed at the position where the geophone is placed, the position of the geophone can be determined by taking out the geophone, for example. can be changed. In other words, since no filler such as mortar is used, installation of the geophone can be completed in a short time. Therefore, it is possible to improve the analysis accuracy of the elastic wave from the front of the face due to blasting, and to easily change the position of the geophone.
In the TFT method, since the geophone is placed at the head of the rock bolt, it is necessary to prepare protective equipment to prevent damage to the geophone due to flying stones from blasting or contact with construction machinery. rice field. In other words, the TFT method has a problem that the number of parts required for face forward exploration increases. On the other hand, since the geophone of the present invention is arranged in the vibration receiving hole, the protective equipment is not required, and the number of parts required for searching the front face can be reduced.

Further, the detector is connected to a blasting busbar that connects the explosive used in the blasting for excavation and the blaster, and is arranged between the explosive and the blaster, and the explosive is used in tunnels. It is preferable that the blaster is arranged at the face, and the blaster is arranged closer to the tunnel portal than the receiving hole.
According to this configuration, the configuration for realizing blasting for excavation can be simplified. Also, the blaster can be protected from flying stones caused by blasting.

Moreover, it is preferable that a data logger connected to the geophone is further provided, and the data logger is provided with a wireless section that receives the shot marks from the detector by wireless communication.
According to such a configuration, the data logger can start recording data generated when the geophone receives the elastic wave, triggered by the reception of the shot mark. In other words, the time from the start of blasting to the reception of elastic waves can be reliably recorded. Moreover, since the data logger and the detector communicate wirelessly, the positional relationship between the data logger and the detector can be appropriately adjusted according to the progress of excavation work.

The geophone includes a geophone for detecting the elastic wave, and the data logger includes a control section for opening and closing the holding section, and a recording section for recording data of the elastic wave detected by the geophone. is preferred.
According to such a configuration, it is possible to simplify the configuration for realizing the detection of elastic waves.

Moreover, it is preferable that the data logger is arranged in the vibration receiving hole.
According to such a configuration, it is not necessary to prepare protective equipment to prevent the data logger from being damaged due to contact with flying stones or construction machinery due to blasting. Therefore, it is possible to reduce the number of parts for searching the face forward.

Moreover, it is preferable to further include a cable for communicably connecting the geophone and the data logger.
According to such a configuration, after the end of face front exploration, the cable can be hauled in to easily recover the geophone at the back of the receiving hole.

Moreover, it is preferable to further include a pushing portion for pushing the geophone into the depth of the vibration receiving hole.
According to such a configuration, the geophone can be easily arranged at the deep position of the vibration receiving hole.

Further, the blasting for excavation is step blasting in which blasting is performed in three or more stages at a predetermined scheduled blasting timing, and the time interval from the first blasting to the second blasting is set to the third blasting from the second blasting. is preferably longer than the time interval until blasting.
According to such a configuration, it is possible to obtain time for measuring elastic waves (reflected waves) caused by the first blasting. As the distance to the fracture zone and the seep zone in front of the face increases, the time until the reflected wave is observed increases. If the time interval from the 1st blasting to the 3rd blasting is set longer than the time interval, the geophone can detect the second blasting without being affected by it. Therefore, the noise of the reflected wave from the first blast is reduced. As a result, it is possible to increase the search distance of face forward search.

ADVANTAGE OF THE INVENTION According to this invention, while being able to raise the analysis accuracy of the elastic wave from the face front by blasting, it can facilitate the position change of a geophone.

1 is an overall configuration diagram of a face forward exploration system of the present embodiment; FIG. It is a side view internal sectional view of a geophone. It is explanatory drawing when the holding|maintenance part of a geophone is opened. (a) is a side view internal cross-sectional view of the push-in portion, and (b) is a side view internal cross-sectional view of the base portion of the geophone. It is explanatory drawing of step blasting in blasting for excavation. It is a flowchart which shows the procedure of the face front searching method of this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with appropriate reference to the drawings. Each drawing is merely a schematic representation to the extent that the present invention can be fully understood. Accordingly, the present invention is not limited to the illustrated examples only. In addition, in each figure, the same code|symbol is attached|subjected about a common component and a similar component, and those overlapping description is abbreviate|omitted.

[composition]
FIG. 1 is an overall configuration diagram of the face front exploration system of the present embodiment, and is a plan view of the inside of a tunnel pit. The face front detection system includes a blaster 1 , a detector 2 , a geophone 3 and a data logger 4 .
The blaster 1 is equipment for starting blasting for excavation. Blasting for excavation is to blast explosives (not shown) placed on the tunnel face to crush the ground. The blaster 1 is connected to the explosive by a blasting busbar 5 . The blaster 1 is arranged on the pithead side of a vibration receiving hole 6 drilled in the tunnel peripheral wall.
The detector 2 detects shot marks indicating the start timing of blasting for excavation. The detector 2 is communicably connected to the data logger 4 wirelessly (eg, WiFi (registered trademark)). The detector 2 can send the detected shot marks to the data logger 4 . The detector 2 is connected to the blasting busbar 5 and placed in the tunnel between the explosive and the blaster 1 .
Geophone 3 detects elastic waves 8 generated due to excavation blasting. The geophone 3 is arranged in the vibration receiving hole 6 . The elastic wave 8 reaches the geophone 3 through the ground after being reflected by the fracture zone 9 in front of the tunnel face.
The data logger 4 is a device that records various data. The data logger 4 is communicably connected to the geophone 3 via a cable 7 and can receive data of the elastic waves 8 detected by the geophone 3 .

[Details of Geophone]
FIG. 2 is a side view internal cross-sectional view of the geophone 3 . The geophone 3 has a substantially rod-like shape with a diameter smaller than that of the vibration receiving hole 6 . The geophone 3 includes a housing 31 , a cap 32 , a geophone 33 , a holder 34 and a motor 35 .
The housing 31 is a substantially cylindrical body. A holding portion 34 in a closed state and a motor 35 are arranged in the hollow portion of the housing 31 . A part of the side surface of the housing 31 is opened, and the holding portion 34 accommodated in the housing 31 can be deployed radially outward through the opening.
The cap 32 is the head of the geophone 3 and is connected to the tip of the housing 31 .
The geophone 33 is a sensor (seismometer) that detects elastic waves 8 reflected by the fracture zone 9 due to excavation blasting. Geophone 33 is received in cap 32 .

The holding part 34 is a member that fixes the geophone 3 to the hole wall of the vibration receiving hole 6 . The holding portion 34 includes a block 341 , a pair of first arms 342 and 342 , a second arm 343 and an actuator 344 . A parallel link mechanism is formed by the block 341 , the pair of first arms 342 , 342 and the actuator 344 .
The block 341 is a portion that comes into contact with the hole wall of the vibration receiving hole 6 when the holding portion 34 is in the open state.
A pair of first arms 342 , 342 connect block 341 and actuator 344 .
The second arm 343 connects the block 341 and the base side surface of the housing 31 .
Actuator 344 is driven by motor 35 to move in the axial direction.
When the motor 35 rotates forward, it moves the actuator 344 to the positive side in the axial direction (direction from the base of the housing 31 toward the cap 32). direction toward the root). When the actuator 344 is moved to the positive side in the axial direction, the parallel link mechanism is expanded to open the holding portion 34 (see FIG. 3), and when the actuator 344 is moved to the opposite side in the axial direction, the parallel link mechanism is folded. holding portion 34 is closed (see FIG. 2).
Although FIG. 2 shows the end cap 37 covering the base of the housing 31 , the end cap 37 is removed when the geophone 3 is used, and the cable 7 is connected to the geophone 3 .

[Operation of Geophone]
FIG. 3 is an explanatory view when the holding portion 34 of the geophone 3 is opened. Assume that the geophone 3 with the holding portion 34 in the closed state is placed at a predetermined position within the vibration receiving hole 6 . For example, an operator can use an analysis device to send a control signal to the geophone 3 via the data logger 4 . When the control signal is transmitted, the geophone 3 causes the motor 35 to rotate forward according to the control signal, thereby moving the actuator 344 to the positive side in the axial direction. Then, the block 341 moves outward in the engaging direction of the housing 31 through the pair of first arms 342 and 342 and the second arm 343 and comes into contact with the hole wall of the vibration receiving hole 6 . Therefore, the geophone 3 is fixed to the hole wall of the vibration receiving hole 6, and the geophone 33 can be substantially brought into close contact with the ground. As a result, the noise of the elastic wave 8 detected by the geophone 33 can be reduced.
In addition, there are cases where it is desired to change the placement position of the geophone 3 for reasons such as poor detection of the elastic wave 8 due to the presence of bad ground at the placement position of the geophone 3 . In this case, for example, an operator uses an analysis device to transmit a control signal to the geophone 3 via the data logger 4 . The geophone 3 reverses the motor 35 according to the control signal to move the actuator 344 to the opposite side in the axial direction. Then, the contact between the block 341 and the hole wall of the vibration receiving hole 6 is released via the first arms 342 , 342 and the second arm 343 , and the block 341 is accommodated in the housing 31 . As a result, the geophone 3 can be moved and changed to a desired arrangement position.

[Pushing part]
FIG. 4A is a side view internal cross-sectional view of the push-in portion, and FIG. 4B is a side view internal cross-sectional view of the base portion of the geophone. The push-in portion 10 is a tubular body that pushes the geophone 3 into the vibration receiving hole 6 . The pushing portion 10 includes a plurality of rod portions 101, a plurality of joint portions 102, and guide receiving portions 103,103. Further, the geophone 3 has guide portions 36, 36 at its root portion.
The rod portion 101 is a cylindrical body forming the body portion of the push-in portion 10 . The cable 7 can be inserted through the hollow portion of the rod portion 101 .
The joint portion 102 connects adjacent rod portions 101 . By adding the rod portion 101 using the joint portion 102, the full length of the push-in portion 10 can be adjusted.
The guide receiving portions 103 , 103 receive the guide portions 36 , 36 of the geophone 3 . The guide receiving portions 103 , 103 are connected to the distal end portion of the leading rod portion 101 and extend from the distal end portion of the leading rod portion 101 in the axial direction of the push-in portion 10 and so as to face the geophone 3 . extended.
The guide portions 36 , 36 of the geophone 3 are needle-like bodies extending from the root portion of the geophone 3 in the axial direction of the geophone 3 and facing the push-in portion 10 . The guide portions 36 , 36 are received in the guide receiving portions 103 , 103 , so that the axial rotation position of the push-in portion 10 and the axial rotation position of the geophone 3 can be aligned.

As shown in FIG. 4(b), the geophone 3 is placed at a predetermined position (out of reach of the operator) in the vibration receiving hole 6 with the cable 7 connected to the base of the geophone 3. Suppose that When desiring to push the geophone 3 deep into the vibration receiving hole 6, the operator inserts the cable 7 through the hollow portion of the push-in portion 10 and causes the guide receiving portions 103, 103 to receive the guide portions 36, 36. FIG. After that, the operator pushes the push-in part 10 deep into the vibration receiving hole 6 to push the geophone 3 into the vibration receiving hole 6 and arrange the geophone 3 at a desired position.

[Details of data logger 4]
Returning to FIG. 1, the data logger 4 includes a radio section (not shown) and a recording section (not shown). The radio section is a functional section that receives shot marks from the detector 2 by radio communication. The recording unit is a functional unit that records data of elastic waves 8 detected by the geophone 33 .
As shown in FIG. 1, the data logger 4 is arranged at the entrance of the receiving hole 6 . The data logger 4 has a cylindrical body with a diameter substantially equal to or smaller than the hole diameter of the receiving hole 6 . The data logger 4 also has a disk-shaped flange portion having a larger diameter than the body portion of the data logger 4 . On the other hand, at the entrance of the vibration receiving hole 6, a concave portion (diameter enlarged portion) having a diameter larger than that of the vibration receiving hole 6 is formed. When the operator places the data logger 4 at the entrance of the vibration receiving hole 6, the flange portion of the data logger 4 is received in the recess at the entrance of the vibration receiving hole 6 and locked to the plane of the recess. A worker can fix the data logger 4 to the entrance of the vibration receiving hole 6 by fixing the flange portion to the recess with a screw or the like. Further, by making the depth of the concave portion larger than the plate thickness of the flange portion, the entire data logger 4 can be arranged inside the tunnel peripheral wall rather than the tunnel peripheral wall. As a result, the possibility that flying stones from blasting for excavation collide with the data logger 4 can be made extremely small.

[cable]
As shown in FIG. 1, cable 7 connects data logger 4 and geophone 3 . After completing the front face exploration, the worker takes out the data logger 4 from the entrance of the vibration receiving hole 6 . Next, the worker can easily collect the geophone 3 in the depth of the vibration receiving hole 6 by pulling the cable 7 .

[Excavation blasting]
The excavation blasting of the present embodiment can be, for example, step blasting in which three stages of blasting are performed at predetermined scheduled blasting timings. Note that the number of steps is not limited to three, and may be four or more. FIG. 5 is an explanatory diagram of step blasting in blasting for excavation. A virtual point P and circles Q1 to Q3 are prepared on the tunnel cutting wave surface shown in FIG. Circles Q1 to Q3 are concentric circles with point P as the center. The radius of circle Q2 is twice that of circle Q1. The radius of circle Q3 is three times that of circle Q1. Place gunpowder at point P. The point P becomes an investigation hypocenter. Also, one or more explosives are arranged on the circumference of each of the circles Q1 to Q3. However, the gunpowder placed at the point P and the gunpowder placed on the circumference of each of the circles Q1 to Q3 are aligned on a straight line. Therefore, the explosive placed at the point P and the explosive placed on each of the circles Q1 to Q3 are arranged at regular intervals.
When the blaster 1 is operated and blasting for excavation is started, the explosive at the point P connected to the blasting generatrix 5 is blasted, then the explosive at the circle Q1, the explosive at the circle Q2, and the explosive at the circle Q3 are sequentially blasted. . Since the explosive arranged at the point P and the explosive arranged in each of the circles Q1 to Q3 are arranged at equal intervals, the blasting intervals of the respective explosives are the same. If the blasting timing of the explosive at the point P is 0 ms, for example, the explosive timing of the circle Q1 is 250 ms later, the explosive timing of the circle Q2 is 500 ms later, and the explosive timing of the circle Q3 is 750 ms later. Geophone 3 detects elastic waves 8 at 0 ms, 250 ms, 500 ms, and 750 ms after blasting timing.

Although the above description is of ordinary stepped blasting, this embodiment introduces stepped blasting that skips steps. In the case of the example of FIG. 5, the step blasting for step skipping is blasting after 500 ms on the circumference of circle Q1, blasting after 750 ms on the circumference of circle Q2, and blasting after 1000 ms on the circumference of circle Q3. Therefore, there is no blasting after 250ms, and the geophone 3 detects elastic waves 8 at blasting timings of 0ms, 500ms, and 750ms. By step skipping, the measurement time (500 ms) of the elastic wave 8 (reflected wave) caused by the blasting of the explosive at the point P can be earned. As the distance to the fracture zone 9 in front of the face and the spring water zone increases, the time until the reflected wave is observed increases, but the blasting of the gunpowder in circle Q1 is omitted, and the measurement time is 500 ms (silent interval). , the elastic wave 8 generated by the blasting of the explosive at the point P is detected by the geophone 3 without being affected by the blasting of the explosive at the circle Q2. Therefore, the noise of the elastic wave 8 due to the blasting of the explosive at the point P is reduced. As a result, it is possible to increase the search distance of face forward search. Specifically, in the case of ordinary stepped blasting, the search distance was about 100 to 150m, but in the case of stepped stepped blasting, it was confirmed that the search distance could be extended to about 400m.

In the more general step blasting of step skipping, the time interval from the first blasting to the second blasting is made larger than the time interval from the second blasting to the third blasting. . According to such a configuration, it is possible to obtain time for measuring elastic waves (reflected waves) caused by the first blasting. As the distance to the fracture zone and the seep zone in front of the face increases, the time until the reflected wave is observed increases. If the time interval from the 1st blasting to the 3rd blasting is set longer than the time interval, the geophone can detect the second blasting without being affected by it. Therefore, the noise of the reflected wave from the first blast is reduced. As a result, it is possible to increase the search distance of face forward search.

[motion]
A face forward search method performed by the face forward search system will be described. FIG. 6 is a flow chart showing the procedure of the face front searching method according to the present embodiment.
First, an operator places the geophone 3 in the vibration receiving hole 6 (step S1). A worker can push the geophone 3 deep into the vibration receiving hole 6 using the push-in portion 10 . Therefore, the position of the geophone 3 within the vibration receiving hole 6 can be appropriately set. Geophone 3 is connected to data logger 4 by cable 7 .
Next, the operator operates the analysis device to fix the geophone 3 to the vibration receiving hole 6 (step S2). Specifically, the analysis device transmits a control signal to the geophone 3 via the data logger 4 . The geophone 3 that has received the control signal brings the block 341 of the holding portion 34 into contact with the hole wall of the vibration receiving hole 6 . When it is desired to change the position of the geophone 3 due to ground failure or the like, the operator operates the analysis device to release the fixation of the holding portion 34, move it to a desired position, and then move the holding portion 34 again. The block 341 is brought into contact with the hole wall of the vibration receiving hole 6 to fix the vibration receiver 3 to the vibration receiving hole 6 .
Next, the worker places the data logger 4 in the receiving hole 6 (step S3).

Next, the operator operates the blaster 1 to start blasting for excavation (step S4). Explosive blasting for excavation blasts the explosive placed on the tunnel face and generates an elastic wave 8 . After being reflected by the crush zone 9, the elastic wave 8 reaches the receiving hole 6 via the ground.
Next, the detector 2 detects shot marks according to the operation of the blaster 1 (step S5). The detector 2 transmits the detected shot marks to the data logger 4 . Therefore, the data logger 4 can know the start timing of blasting for excavation, and can specify the detection timing of the elastic wave 8 by the geophone 3 .
Next, the geophone 3 detects the elastic wave 8 reflected by the fracture zone 9 (step S6). Specifically, by fixing the geophone 3 by the holding portion 34 , the geophone 33 substantially in close contact with the ground can detect the elastic wave 8 . Geophone 3 transmits data of detected elastic wave 8 to data logger 4 via cable 7 .
Next, the data logger 4 records the data of the elastic waves 8 received from the geophone 3 . For example, the data logger 4 can associate each piece of data of the detected elastic waves 8 with the detection timing of the elastic waves 8 specified from the start timing of blasting for excavation. In addition, for example, the data logger 4 can record the data of the elastic wave 8 on the built-in recording medium. The worker takes out the recording medium from the data logger 4 and connects the recording medium to the analysis device, so that the analysis device can acquire the data of the elastic wave 8 and perform a predetermined analysis.
This completes the face forward exploration method.

After completing the exploration of the face front, the worker takes out the data logger 4 from the receiving hole 6 . In addition, the operator can easily take out the geophone 3 by hauling in the cable 7 connected to the data logger 4 .

According to this embodiment, since the blasting for excavation is the epicenter, the excavation work does not have to be interrupted. In addition, since the geophone 3 is placed in the receiving hole 6, compared to the TFT method, the elastic wave 8 generated due to the blasting for excavation (reflection from the fracture zone in front of the face, the spring water zone, etc.) (including waves) can be reduced. In addition, since the holding part 34 fixes the geophone 3 to the hole wall of the vibration receiving hole 6, the sensor (geophone 33) of the geophone 3 can be brought into close contact with the ground. Noise in elastic waves detected by the sensor can be reduced. Therefore, it is possible to improve the analysis accuracy when the analysis device analyzes the elastic wave 8 detected by the geophone 3 . In addition, since the holding part 34 can release the fixation of the geophone 3 to the hole wall of the vibration receiving hole 6, even if a defective ground is distributed at the position where the geophone 3 is arranged, the geophone 3 can be taken out. The position of geophone 3 can be changed. That is, since the conventional filling material such as mortar is not used, installation of the geophone 3 can be completed in a short time. Therefore, it is possible to improve the analysis accuracy of the elastic wave 8 from the front of the face due to blasting, and to easily change the position of the geophone 3 .
In addition, since the geophone 3 is arranged in the receiving hole 6, the protective equipment required in the conventional TFT method is no longer necessary, and the number of parts for prospecting the front face can be reduced.

Further, the data logger 4 can start recording data generated when the geophone 3 receives the elastic wave 8 by using the reception of the shot mark as a trigger. That is, the time from the start timing of blasting to the reception timing of the elastic wave 8 can be reliably recorded. Moreover, since the data logger 4 and the detector 2 communicate wirelessly, the positional relationship between the data logger 4 and the detector 2 can be appropriately adjusted according to the progress of excavation work.
In addition, since the data logger 4 is arranged in the vibration receiving hole 6, like the vibration receiver 3, protective equipment becomes unnecessary, and the number of parts for performing face forward exploration can be reduced.

[Modification]
(a): The detector 2 and the data logger 4 may be communicatively connected not wirelessly but by wire.
(b): Instead of using the cable 7, the data logger 4 and the geophone 3 may be connected to communicate wirelessly, and the data logger 4 wirelessly receives the data of the elastic wave 8 from the geophone 3. may
(c): A plurality of vibration receiving holes 6 can be prepared, and the vibration receiver 3 and the data logger 4 can be arranged in each of the vibration receiving holes 6 . Also, a plurality of geophones 3 may be arranged in the vibration receiving hole 6 . Further, the drilling direction of the vibration receiving hole 6 does not have to be perpendicular to the extending direction of the tunnel.
(d): Step skipping When performing step blasting, the number of steps to be skipped and the number of times can be appropriately set.
(e): The data logger 4 may be configured to have an embedded storage unit without a built-in removable recording medium. In this case, the analyzing device and the data logger 4 are communicably connected by wire or wirelessly, and the data logger 4 can transmit the data of the elastic wave 8 to the analyzing device.

(f): It is also possible to realize a technique in which the various techniques described in this embodiment are appropriately combined.
(g): The software described in this embodiment can be implemented as hardware, and the hardware can be implemented as software.
(h): In addition, hardware, software, flowcharts, etc. can be changed as appropriate without departing from the scope of the present invention.

Reference Signs List 1 blaster 2 detector 3 geophone 4 data logger 5 blasting generatrix 6 vibration receiving hole 7 cable 8 elastic wave 9 crush zone 10 pushing part 101 rod part 102 joint part 103 guide receiving part 31 housing 32 cap 33 geophone 34 holding part 341 Block 342 First Arm 343 Second Arm 344 Actuator 35 Motor 36 Guide Part 37 End Cap

Claims (10)

a blaster for initiating drilling blasting;
a detector for detecting a shot mark indicating the start timing of the blasting for excavation;
A geophone that detects an elastic wave generated due to the blasting for excavation,
The face front exploration system, wherein the geophone is disposed in a bore hole drilled in a tunnel wall surface, and includes a holding section for fixing the geophone to the bore wall of the borehole. The detector is connected to a blasting busbar that connects the explosive used for blasting for excavation and the blaster, and is arranged between the explosive and the blaster,
The explosive is placed in the tunnel face,
The face front exploration system according to claim 1, wherein the blaster is arranged closer to the tunnel portal than the receiving hole. further comprising a data logger connected to the geophone;
The data logger is
3. The face front exploration system according to claim 1, further comprising a radio unit that receives the shot mark from the detector by radio communication. The geophone is
comprising a geophone that detects the elastic waves;
The data logger is
a control unit that opens and closes the holding unit;
4. The face forward exploration system according to claim 3, further comprising a recording unit for recording data of elastic waves detected by said geophone. 5. The face front exploration system according to claim 3, wherein the data logger is arranged in the receiving hole. The face front exploration system according to any one of claims 3 to 5, further comprising a cable that communicably connects the geophone and the data logger. The face front surveying system according to any one of claims 1 to 6, further comprising a push-in section for pushing the geophone into the depth of the geophone. A geophone for detecting elastic waves generated due to blasting for excavation,
A geophone arranged in a vibration receiving hole drilled in a tunnel peripheral wall surface, and comprising a holding part for fixing the geophone to the hole wall of the vibration receiving hole. a first step of arranging a geophone in a receiving hole drilled in a tunnel peripheral wall;
a second step of fixing the geophone to a hole wall of the vibration receiving hole;
a third step of operating the blaster to start drilling blasting;
a fourth step in which a detector detects a shot mark indicating the start timing of the blasting for excavation;
and a fifth step in which the geophone detects an elastic wave generated due to the blasting for excavation. The blasting for excavation is step blasting in which three or more stages are blasted at a predetermined scheduled blasting timing,
10. A face front exploration method according to claim 9, wherein the time interval from the first blasting to the second blasting is set longer than the time interval from the second blasting to the third blasting.

Images