JP7816856B2 - Protective structure and installation method for measuring equipment - Google Patents

Description

The present invention relates to a protective structure and installation method for measuring equipment.

In the construction of mountain tunnels, B-measurements are carried out with the main purpose of reflecting the results in the design and construction, depending on the ground conditions and the design content. This B-measurement is intended to determine the appropriateness of the support materials and construction methods used, as well as to ensure the rational and economical design and construction of the tunnels further inside.
This B measurement includes underground displacement measurement, steel support stress measurement, sprayed concrete stress measurement, and rock bolt axial force measurement, and all of these involve installing special sensors to obtain quantitative data (measurement data) to evaluate the current characteristics of the ground, as well as the future characteristics of the ground as excavation progresses.
For example, Patent Document 1 proposes a method for predicting ground conditions that enables highly accurate prediction of ground conditions ahead of the tunnel face by accurately identifying horizontal internal displacement in addition to tunnel subsidence.
Specifically, in the tunnel arch section of a tunnel with a cross-sectional shape that includes at least a semicircular section, multiple inclinometers are installed at intervals in the axial direction of the tunnel, measurement data from each inclinometer is obtained, the change in inclination angle is calculated from the measurement data from each adjacent inclinometer, and the ground conditions ahead of the tunnel face are predicted based on the calculation results.The inclinometers are installed at an angle of 55 to 65 degrees from the spring line, with the intersection of the horizontal spring line and the vertical center line as the center.

JP 2016-61080 A

Incidentally, in the construction of mountain tunnels, the mainstream method for collecting measurement data measured by sensors is the wired collection method, in which data is collected from the sensors via wired cables to a data logger or a PC (personal computer).
However, there are issues such as the time and effort required to install wired cables inside the tunnel, to protect them from flying blasting stones, and to secure a power source, and the danger involved in wiring work near the tunnel face.
Furthermore, it has become standard practice these days to set up a system in which data is constantly transferred from the above-mentioned data logger to a PC located in a guardhouse outside the mine via a communication cable (maximum communication distance, for example, 1.2 km), and the data can then be accessed from the PC via LAN at any time from the work site office. However, there are also sites where LAN cables are laid directly inside the mine or Wi-Fi (registered trademark) access points are installed, making maintenance of the communication cables (to prevent damage) an issue.

The wired data collection method described above requires workers and managers to have access to the vicinity of the measurement location during installation and construction. Because various vehicles and construction workers pass through the tunnel, it is necessary to select a time and measurement location that will not interfere with construction work.
In other words, since there is a concern that the surface may fall off at the face when the measurement location is near the face, it is desirable for safety reasons to locate the measurement location at a location some distance away from the face of the tunnel.
On the other hand, measuring the ground at a location some distance from the working face may lead to a decrease in the accuracy of the property evaluation, considering that measurements close to the ground are suitable for evaluating the cross-sectional position and the properties of the ground ahead.

The objective of this invention is to provide a protective structure and installation method for measuring equipment that eliminates the hassle and danger associated with wiring, covering, and maintaining wired cables, does not restrict measurement locations, allows measurement data to be quickly fed back into subsequent mountain tunnel construction, and effectively protects measuring equipment from flying blasting stones and the like.

In order to achieve the above object, one aspect of the protective structure for measuring equipment according to the present invention comprises:
A protective structure for measuring equipment that protects measuring equipment that measures quantitative data as mountain tunnels are excavated,
Among the primary sprayings applied to the excavated face and sides of the mountain tunnel, a steel support made of H-shaped steel is erected against the primary spraying surface of the primary spraying applied to the side, and a box-out space is provided at the installation position of a sensor on the primary spraying surface;
A secondary spraying that is constructed so as to involve the steel support and the box-out space;
The sensor is installed inside an installation hole extending from the box-out space to partway through the natural ground, and is an underground displacement meter or a rock bolt axial force meter;
A protective plate is provided to cover the box-opening space,
The protective plate is attached by anchors driven into at least the secondary spray.

According to this aspect, a sensor which is an underground displacement meter or a rock bolt axial force meter is installed inside an installation hole which is provided at the sensor installation position on the primary spray surface and extends from the box-out space to halfway into the ground, and a protective plate which is arranged to cover the box-out space is attached by anchors which are driven into at least the secondary spray, so that the protective plate can be securely and stably attached to the secondary spray via the anchors.
Furthermore, it eliminates the hassle and danger associated with wiring, protection, and maintenance of wired cables, there are no restrictions on measurement locations, measurement data can be quickly fed back to subsequent mountain tunnel construction, and measuring equipment can be effectively protected from flying blasting stones and the like.
For example, when secondary sprayed concrete is filled by embedding anchors that have already been attached to the protective plate, the anchors cannot be reliably embedded in the concrete depending on the filling (wraparound) of the concrete around the anchors. In contrast, with this embodiment, in which the anchors are driven into the secondary spray after filling, the protective plate can be reliably fixed against the secondary spray with the anchors without being affected by the filling ability of the concrete.
Here, "driven into at least the secondary spray" includes not only a configuration in which the anchor is driven only into the secondary spray, but also a configuration in which the anchor penetrates the secondary spray and reaches the primary spray on its back side.

In addition, "measuring equipment" includes devices that include a sensor such as an underground displacement meter or rock bolt axial force meter and a communication device that transmits the measurement data acquired by the sensor, as well as devices that include a unit that integrates a sensor, a communication device that transmits the measurement data acquired by the sensor, and a data logger that stores the measurement data.

The communication device is equipped with, for example, an LPWA wireless communication module and a communication antenna that transmits measurement data to another communication device located on the tunnel entrance side. By equipping the communication device with an LPWA wireless communication module and transmitting measurement data (quantitative data) to another communication device located on the tunnel entrance side, long-distance wireless communication in mountain tunnels can be achieved with low power consumption. This makes it possible to quickly feed back measurement data to subsequent mountain tunnel construction.
Here, LPWA (Low Power Wide Area) refers to a wireless communication method that enables wide-area data communication and low power consumption (for example, a communication method using the 920 MHz ISM (Industrial Scientific and Medical Band)). Note that in this specification, "long-distance communication" means wireless communication of measurement data over a distance of, for example, 100 m or more.

Measurement data received by another communication device installed at the tunnel entrance is transmitted, for example, via a network, to a PC or server device in the work site office, or to user terminals (smartphones, tablets, personal computers, etc.) carried by construction personnel (construction managers, construction company head office/branch staff, construction contractors, etc.). By applying LPWA wireless communication, the number of other communication devices installed at the tunnel entrance can be reduced, and depending on the length of the mountain tunnel, it may be possible to transmit measurement data measured by sensors to a server device, etc. via a network using only one other communication device, for example.

The measurement data sent to the server device is then transmitted via the server device to user terminals owned by multiple construction workers, allowing the multiple user terminals to share the measurement data simultaneously and in real time.
Furthermore, by having at least one of the server device and the user terminal determine the ground properties and/or ground evaluation corresponding to the ground properties (degree of hardness of the ground, stability/instability of the ground, suitability of the support pattern, etc.) based on the measurement data, multiple user terminals, for example, can quickly identify the suitability of the initially planned support pattern corresponding to the current ground properties and degree of hardness of the ground, etc.
Furthermore, if the current ground conditions are worse (for example, softer) than those in the initial planning stage, it will be possible to quickly review the support pattern, enabling construction management to be achieved that guarantees high construction safety even in the event of a sudden change in ground conditions.

Another aspect of the protective structure for measuring equipment according to the present invention is
The present invention is characterized by having a support unit in which a wire mesh or support rod is attached to the steel support, and the box-out space is provided at the installation position of the sensor in the wire mesh or support rod.

According to this aspect, the steel support is integrated with the wire mesh or support rods, and the support unit has a box-out space in the wire mesh or support rods where the sensor is installed, thereby enabling the creation of an efficient protective structure.

Another aspect of the protective structure for measuring equipment according to the present invention is
The protective plate is made of resin.

According to this aspect, since the protective plate is made of resin, there is no risk of impeding transmission when transmitting measurement data from a communication device included in the measuring equipment to another communication device located on the mine entrance side.
For example, if the protective plate is made of metal, there is a risk that transmission may be hindered. Here, the "communication device" refers to a wireless communication device.
Furthermore, when the protective plate is a polycarbonate plate, for example, with a thickness of about 6 mm or 10 mm, it has been confirmed that the polycarbonate plate does not crack during an indoor test conducted by the present inventors in which the plate was hit hard with a large hammer, making the protective plate excellent in impact resistance in addition to the above-mentioned ability to prevent communication interference.

Furthermore, one aspect of the measuring device installation method according to the present invention includes:
A method for installing measuring equipment that includes at least a sensor and that measures quantitative data as a mountain tunnel is excavated, comprising:
Process A: erecting a steel support structure made of H-shaped steel against the primary spraying surface of the primary spraying applied to the side of the excavated face and side of the mountain tunnel, and installing a box-out member at the planned installation position of the underground displacement meter or rock bolt axial force meter included in the sensor;
A process B in which a secondary spraying is carried out so as to encase the steel support and the box-punched member;
The method is characterized by having a process C in which an installation hole is constructed by drilling partway through the ground using the box-punching member, the sensor is installed inside the installation hole, the box-punching member is removed to form a box-punching space, a protective plate is arranged to cover the box-punching space, and the protective plate is attached by driving anchors into the ground at least against the secondary spraying.

According to this method, steel support is erected on the surface of the primary spraying, and a box-cutting member is installed at the planned installation location of a sensor such as an underground displacement gauge or rock bolt axial force meter. The secondary spraying is then carried out, enveloping the steel support and the box-cutting member. The sensor is then installed inside an installation hole drilled partway into the ground via the box-cutting member. A protective plate is then placed to cover the box-cutting space created by removing the box-cutting member. By attaching the protective plate by driving anchors into at least the secondary spraying, a protective structure in which the measuring equipment is effectively protected by the protective plate can be efficiently constructed inside a mountain tunnel. Furthermore, the protective plate can be securely and stably attached to the secondary spraying via the anchors.

In another aspect of the measuring device installation method according to the present invention,
In the step A, a wire mesh or support rod is attached to the steel support, and the box punch member is attached to the wire mesh or support rod at the intended position where the sensor is to be installed, and a support unit is erected.

According to this aspect, an efficient method for installing measuring equipment can be achieved by erecting a support unit with a box punch member attached to the intended location of the sensor, among the wire mesh or support rods attached to the steel support.

In another aspect of the measuring device installation method according to the present invention,
In the step C, the anchor is a fully threaded bolt, and the anchor is detachably fixed to at least the secondary spraying.

According to this aspect, by fixing the anchor, which is a fully threaded bolt, in a manner that allows it to be attached and detached at least to the secondary spray, it is possible to drive the anchor into the secondary spray while fixing the protective plate with a nut that is screwed onto the head of the fully threaded bolt.
Here, the fully threaded bolt is preferably in a form in which the tip thereof is sharpened so that it can be used as a driven anchor.
It is also preferable to provide a double nut on the head of the fully threaded bolt, as this prevents the nut that secures the protective plate from being crushed when the bolt is driven in.

In another aspect of the measuring device installation method according to the present invention,
In step C, the protective plate has a rectangular shape in plan view that is elongated in the circumferential direction of the mountain tunnel, and has multiple anchor holes opened along its periphery, and the anchors are inserted into the anchor holes and driven in.

According to this aspect, by inserting and driving anchors into each of the multiple anchor holes opened along the periphery of the protective plate, the protective plate can be reliably and stably fixed to the secondary spray via the multiple anchors while preventing damage to the protective plate due to the driving of the anchors.
Here, after the anchor is inserted into the anchor hole and driven in, a nut is screwed onto the head of the anchor, so that the nut engages around the anchor hole and supports the underside of the protective plate.
In addition, by loosening the nuts and removing the protective plate, the communicators and data loggers in the box-removing space can be easily replaced. After the communicators and data loggers have been removed from the box-removing space, it is recommended that formwork be installed to close the box-removing space, and the space be filled with mortar or the like for post-cleaning processing.

The protective structure and installation method for measuring equipment of the present invention eliminates the time and danger associated with wiring, protection, and maintenance of wired cables, does not restrict measurement locations, allows measurement data to be quickly fed back into subsequent mountain tunnel construction, and effectively protects measuring equipment from flying blasting stones and the like by using protective plates that are securely and stably attached at least against secondary spraying.

1 is a plan view showing an example of a protective structure for a measuring instrument according to an embodiment, together with an example of a natural ground measurement system. 4D is an enlarged view of part II of FIG. 1, a longitudinal cross-sectional view showing an example of a protective structure for a measuring instrument according to an embodiment, and is a process diagram illustrating a method for installing a measuring instrument according to an embodiment, following FIG. 4D. 3 is a view taken in the direction of the arrow III in FIG. 2, and is a plan view of the protective structure for the measuring equipment according to the embodiment as seen from inside the mountain tunnel. 1A to 1C are process diagrams illustrating a method for installing a measuring device according to an embodiment. 4B is a process diagram illustrating the method for installing the measuring device according to the embodiment, following FIG. 4A. 4B is a process diagram illustrating the method for installing the measuring device according to the embodiment. FIG. 4C is a process diagram illustrating the method for installing the measuring device according to the embodiment. FIG. FIG. 1 is an overall block diagram of an example of a natural ground measurement system. 10 is a diagram illustrating the state after the unit body has been removed from the box removal space 43. FIG.

The protective structure and installation method for measuring equipment according to the embodiment will be described below with reference to the accompanying drawings. Note that in this specification and drawings, substantially identical components will be designated by the same reference numerals, and redundant explanations may be omitted.

[Protective structure and installation method for measuring equipment according to the embodiment]
An example of a protective structure and an installation method for a measuring device according to an embodiment, and an example of a natural ground measurement system will be described with reference to FIGS. 1 to 6 .
Here, Fig. 1 is a plan view showing an example of a protective structure for a measuring instrument according to an embodiment together with an example of a natural ground measurement system, Fig. 2 is an enlarged view of part II in Fig. 1 and is a vertical cross-sectional view showing an example of a protective structure for a measuring instrument according to an embodiment, Fig. 3 is a view taken in the direction of arrow III in Fig. 2 and is a plan view of the protective structure for a measuring instrument according to an embodiment as seen from the inside of a mountain tunnel. Also, Figs. 4A to 4D and Fig. 2 are, in order, process diagrams explaining a method for installing a measuring instrument according to an embodiment. Furthermore, Fig. 5 is an overall block diagram of an example of a natural ground measurement system.

The tunnel to which the illustrated ground measurement system 200 is applied is a mountain tunnel. A mountain tunnel 10 is constructed by drilling a charge hole in the tunnel face 11 using a drilling machine such as a jumbo drill, and then loading and detonating an explosive. Mountain tunnels may also be constructed by mechanical excavation (not shown) using a free-face boring machine or breaker.

After the tunnel is extended to a specified length by blasting or other means, the natural ground in the area enclosed by the two-dot chain line V in Figure 1 is excavated forward, and new steel support 22 (steel arch support) and shotcrete are installed on the tunnel wall 13. A primary spraying 21 of concrete, for example, approximately 5 cm to 15 cm thick, is applied to the surface of the tunnel wall 13, and mirror spraying 21A is applied to the tunnel face 11. After that, steel support 22 made of H-shaped steel or the like is installed at specified intervals in the direction of excavation to protect the tunnel wall. Then, a secondary spraying 23 of concrete, for example, approximately 5 cm to 20 cm thick (an example of shotcrete), is applied, enveloping the steel support 22.

The primary spraying 21 and secondary spraying 23 are carried out by bringing a concrete mixer truck into the tunnel and spraying the concrete with a sprayer. After the secondary spraying 23 is carried out, rock bolts (not shown) are installed as needed. These rock bolts are made of steel bars, for example, approximately 2 to 6 meters long, and are used to support the tensile force caused by deformation of the ground G toward the inside of the tunnel, thereby suppressing deformation of the tunnel wall 13.

The ground measurement system 200 is a system that measures quantitative data as the mountain tunnel 10 is excavated. The ground measurement system 200 has at least one sensor 80 installed on the tunnel wall 13 of the mountain tunnel 10 or on the steel support 22 that supports the tunnel wall 13, a first communicator 32 (see Figure 5, an example of a communicator) that transmits the measurement data acquired by the sensor 80, and a second communicator 61 that is disposed closer to the tunnel entrance 12 than the first communicator 32 and receives the measurement data wirelessly transmitted from the first communicator 32.

As shown in FIG. 5, the data logger 31 and first communicator 32 are integrated to form the unit 30. The data logger 31 supplies an applied voltage or current, performs A/D conversion of the signal from the sensor 80, and stores the digital value after A/D conversion. In the data logger 31, the signal from the sensor 80 is converted into a digital value via A/D conversion, and the converted digital data is stored. The stored data is then transmitted via the communication antenna 33 provided in the first communicator 32.

The first communicator 32 is a slave device of an LPWA (wireless communication module) that conforms to the LoRa Private standard. Meanwhile, the communication master device 60 (base station) incorporates a second communicator 61 equipped with a communication antenna 63 and a tablet PC 62, which is also a component of the natural ground measurement system 200. The tablet PC 62 is connected to the LAN via Wi-Fi or a wired connection, and data files stored in the storage device (memory) of the tablet PC 62 are shared over the network, allowing data to be acquired in real time from the work site office, etc.

The interior of mountain tunnel 10 is filled with various obstacles (mainly made of metal), such as heavy machinery, center carts, and steel soundproof doors, creating an environment where radio waves are attenuated. However, the transmission and reception of measurement data using the LPWA wireless system is, in principle, possible over long distances of approximately 1 to 2 km. Therefore, in the natural ground measurement system 200, the second communication device 61 is installed, for example, at a distance of several hundred meters or more from the sensor 80 near the tunnel face 11. Thereafter, the system is constructed so that measurement data is transmitted to the second communication device 61 closest to the tunnel entrance 12, which is connected to an external network, without the need for relocation.

With the natural ground measurement system 200, measurement data acquired by the sensor 80 is transmitted from the first communication device 32 to the second communication device 61 located on the tunnel entrance 12 side, eliminating the effort and danger associated with wiring, protection, and maintenance of wired cables and eliminating limitations on measurement locations.

The protective structure 100 for measuring equipment shown in Figure 1 is a configuration in which the sensor 80 is an underground displacement meter. Here, in addition to an underground displacement meter, a rock bolt axial force meter may also be used as the sensor 80.

After the secondary spraying 23 is installed, a portion of the underground displacement meter 80 is installed by drilling an installation hole 90 extending from the primary spraying 21 to the ground G. The other portion of the underground displacement meter 80 is installed in a boxed-out space 43 provided inside the secondary spraying 23, and the unit body 30 installed nearby along with the other portion are housed in the boxed-out space 43.

The unit body 30 is placed near the underground displacement meter 80, and the underground displacement meter 80 and the data logger 31 of the unit body 30 are wired via a data cable 39 to form a measuring device 85.

The opening inside the tunnel of the box-out space 43 that houses the underground displacement sensor 80 and the unit body 30 is covered with a protective plate 42 such as a polycarbonate plate.

As shown in Figures 2 and 3, the protective plate 42 has a rectangular shape in plan view, with multiple anchor holes 42a (eight in the illustrated example) drilled along the periphery of the protective plate 42. Anchors 52 are driven into the secondary blast 23 around the box-cut space 43 through each anchor hole 42a. In other words, the protective plate 42 is fixed to the secondary blast 23 by eight anchors 52. Note that the anchors 52 may also pass through the secondary blast 23 and reach the primary blast 21. Here, "rectangle in plan view" includes not only rectangular and square shapes in plan view, but also rectangular and square shapes with curved corners and chamfered corners, as in the illustrated example.

The anchors 52 are formed by fully threaded bolts, some of which protrude from the protective plate 42 into the tunnel. Nuts 54 are fastened via washers 53 to the heads of the fully threaded bolts 52 that protrude into the tunnel. The protective plate 42 is supported by the nuts 54 fastened to the heads of each fully threaded bolt 52, thereby fixing the protective plate 42 to the tunnel side surface 23a of the secondary spray 23.

The protective plate 42 is fixed to the secondary spray 23 via nuts 54 threaded onto multiple fully threaded bolts 52, allowing the protective plate 42 to be removably fixed to the secondary spray 23.

In this way, the unit body 30, which is part of the measuring device 85, and part of the underground displacement meter 80 are housed in the box-out space 43 and are arranged at a distance from the secondary spray 23. A protective plate 42 closes the opening of the box-out space 43 on the inside of the tunnel, and the protective plate 42 is removably fixed to the secondary spray 23 by a plurality of fully threaded bolts 52 and nuts 54 driven into the secondary spray 23, thereby forming a protective structure 100 for the measuring device.

When replacing the unit body 30 with the protective structure 100, the nuts 54 are removed from the multiple fully threaded bolts 52 and the protective plate 42 is removed, allowing the unit body 30 to be easily removed from the box removal space 43 to the inside of the tunnel for replacement.

In addition, in the protective structure 100, the protective plate 42 arranged to cover the box-out space 43 is fixed to the secondary spraying 23 by anchors 52 driven into at least the secondary spraying 23, so the protective plate 42 can be securely and stably attached to the secondary spraying 23 via the anchors 52. Furthermore, this eliminates the effort and risk associated with wiring, protection, and maintenance of wired cables, eliminates restrictions on measurement locations, allows measurement data to be quickly fed back to subsequent mountain tunnel construction, and effectively protects the measuring equipment 85 from flying blasting stones, etc.

For example, when secondary sprayed concrete is filled by burying anchors already attached to the protective plate, the anchors may not be reliably embedded in the concrete depending on the filling (wraparound) of the concrete around the anchors. In contrast, with the protective structure 100 shown in the figure, in which anchors 52 are driven into the secondary sprayed concrete 23 after filling, the protective plate 42 can be reliably fixed to the secondary sprayed concrete 23 by the anchors 52 without being affected by the filling ability of the concrete.

Although not shown in the figures, multiple types of sensors are installed inside the tunnel wall 13 of the mountain tunnel 10 and the natural ground G. These sensors include the underground displacement meter shown in the figure, as well as a rock bolt axial force meter, a shotcrete stress meter, a steel support stress meter, a concrete strain meter, and a thermometer. A single 4-channel data logger, for example, is connected to the shotcrete stress meter and the steel support stress meter. A single 6-channel data logger is also connected to each of the rock bolt axial force meter and the underground displacement meter. Furthermore, multi-channel data loggers can also be manufactured and used. Thus, the number of channels varies depending on the type of sensor, and units containing data loggers are installed to correspond to each number of channels.

Next, an example of a method for installing a measuring device according to an embodiment will be described with reference to Figures 4A to 4D and Figure 2 in that order.

When forming the measuring equipment installation configuration (measuring equipment protective structure 100) shown in Figures 1 and 2, first, as shown in Figure 4A, the wire mesh 50 is fixed to the upper flange 22a of the steel support 22 with a wire or the like (not shown), and a box punch member 91 is fixed to the wire mesh 50 with a wire 95 to form the support unit 70. This box punch member 91 is fixed to the wire mesh 50 at the intended installation position of the sensor 80 when the support unit 70 is erected.

The box-cutting member 91 is a foam material that is integrally molded from, for example, chip urethane (an example of hard urethane) or expanded polystyrene. Here, the box-cutting member 91 may be formed from multiple plate-like bodies that are joined together by a band (not shown).

A guide pipe 92 made of a PVC pipe (VU pipe) or the like is buried inside the box-cutting member 91. This guide pipe 92 is aligned with the planned drilling position where the installation hole 90 should be drilled when the shoring unit 70 is erected.

The formed support unit 70 is erected in the X1 direction so that the back surface of the wire mesh 50 abuts the primary spray surface 21a of the primary spray 21, thereby creating the state before the secondary spray construction shown in Figure 4B.

The wire mesh 50 protrudes slightly toward the front of the tunnel from the already-installed steel support structure 22, and the newly installed wire mesh 50 is firmly secured by tying it to the protruding portion of the wire mesh 50 with binding wire 51.

Here, in addition to erecting the shoring unit 70, after erecting the steel shoring 22, a box-cutting member 91 may be installed at the planned installation position of the underground displacement meter 80 on the primary spraying surface 21a of the primary spraying 21 (this is process A).

Next, as shown in Figure 4C, the secondary spraying 23 is applied so as to encase the steel support 22 and box punch member 91 that form the support unit 70 (this completes Process B).

Next, as shown in Figure 4C, the installation hole 90 is constructed while a drilling machine (not shown) is guided to the planned drilling position via the guide tube 92. Once the drilling position has been determined, the guide tube 92 and box punch member 91 are removed.

Next, as shown in Figure 4D, the remaining box-opening member 91 is removed to form a box-opening space 43 that communicates with the installation hole 90, and the underground displacement meter 80 and unit body 30 are installed in the installation hole 90 and box-opening space 43.

Although not shown in the figures, an iron plate may be fixed to the wire mesh 50, and the data logger 31 may be fixed to the iron plate via a magnet fixed to the back of the data logger 31. Furthermore, it is preferable to connect the underground displacement meter 80 and the data logger 31 via a waterproof connector.

Next, as shown in Figure 2, the opening of the box-removal space 43 facing the inside of the tunnel is blocked with a protective plate 42, and anchors 52 are driven into the secondary spray 23 through multiple anchor holes 42a opened in the protective plate 42. It is preferable to attach double nuts to the heads of the fully threaded bolts 52, as this prevents the nuts securing the protective plate 42 from being crushed when the fully threaded bolts 52 are driven in.

By screwing and tightening nuts 54 onto the heads of each anchor 52 protruding into the tunnel from each anchor hole 42a in the protective plate 42, the protective plate 42 is fixed to the secondary spray 23, forming a protective structure 100 for the measuring equipment (this is process C).

In parallel with the above-mentioned process C, or before or after process C, the second communication device 61 is installed closer to the mine entrance 12 than the first communication device 32.

In the measuring equipment installation method shown in the figure, the box-punching member 91 is provided with a guide tube 92 for guiding the drilling machine that constructs the installation hole 90 to the planned drilling position and for guiding the underground displacement meter 80 to the installation hole 90. This allows the installation hole 90 to be constructed at the desired planned drilling position, and further allows the underground displacement meter 80 to be smoothly installed in the installation hole 90.

Furthermore, after erecting the support unit 70, which is composed of a steel support 22, wire mesh 50 (or support rods), and box punch member 91 integrated onto the primary spray surface 21a of the primary spray 21, the secondary spray 23 can be constructed so as to encase the support unit 70, thereby efficiently constructing a protective structure 100 in which the measuring equipment 85 is effectively protected.

Furthermore, by blocking the opening of the box-removal space 43 on the inside of the tunnel with a protective plate 42 and fixing the protective plate 42 to the secondary blast 23 by driving anchors 52 into the secondary blast 23 through multiple anchor holes 42a opened in the protective plate 42, it is possible to prevent damage to the protective plate 42 due to the driving of the anchors 52, while also ensuring that the protective plate 42 is securely fixed to the secondary blast 23 by the anchors 52.

After the required measurements are completed, when secondary lining (not shown) is constructed inside the secondary spraying 23, the protective plate 42 is removed and the unit body 30 is retrieved from the box removal space 43 in order to reuse the unit body 30. As shown in Figure 6, the box removal space 43 from which the unit body 30 has been retrieved is filled with mortar 45 to close it, and the protective plate 42 is reattached for disposal.

Note that other embodiments may be possible in which other components are combined with the configurations described in the above embodiments, and the present invention is in no way limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately depending on the application form.

10: Mountain tunnel 11: Face 12: Tunnel entrance 13: Tunnel wall 21: Primary spraying 21a: Primary spraying surface 22: Steel support (H-shaped steel)
22a: Upper flange 23: Secondary spraying (sprayed concrete)
23a: Mine surface 30: Unit body 31: Data logger 32: First communication device (LPWA slave, communication device)
33: Communication antenna 39: Data cable 41: Elastic protective material (hard sponge)
42: Protective plate 42a: Anchor hole 43: Box-opening space 44: Fixing bolt 45: Mortar 50: Wire mesh 51: Binding wire 52: Anchor (fully threaded bolt)
53: Washer 54: Nut 60: Communication base unit 61: Second communication device (LPWA base unit)
62: Tablet PC
63: Communication antenna 70: Support unit 80: Underground displacement meter (sensor)
85: Measuring equipment 90: Installation hole 91: Box cutter 92: Guide tube 95: Wire 100: Protective structure for measuring equipment (protective structure)
200: Ground measurement system G: Ground G1: Excavation B: Borehole

Claims (7)

A protective structure for measuring equipment that protects measuring equipment that measures quantitative data as mountain tunnels are excavated,
Among the primary sprayings applied to the excavated face and sides of the mountain tunnel, a steel support made of H-shaped steel is erected against the primary spraying surface of the primary spraying applied to the side, and a box-out space is provided at the installation position of a sensor on the primary spraying surface;
A secondary spraying that is constructed so as to involve the steel support and the box-out space;
The sensor is installed inside an installation hole extending from the box-out space to partway through the natural ground, and is an underground displacement meter or a rock bolt axial force meter;
A protective plate is provided to cover the box-opening space,
A protective structure for measuring equipment, characterized in that the protective plate is attached by anchors that are driven into at least the secondary spray. The protective structure for measuring equipment described in claim 1, characterized by having a support unit in which a wire mesh or support rod is attached to the steel support, and the box-out space is provided in the wire mesh or support rod at the installation position of the sensor. The protective structure for measuring equipment described in claim 1 or 2, characterized in that the protective plate is made of resin. A method for installing measuring equipment that includes at least a sensor and that measures quantitative data as a mountain tunnel is excavated, comprising:
Process A: erecting a steel support structure made of H-shaped steel against the primary spraying surface of the primary spraying applied to the side of the excavated face and side of the mountain tunnel, and installing a box-out member at the planned installation position of the underground displacement meter or rock bolt axial force meter included in the sensor;
A process B in which a secondary spraying is carried out so as to encase the steel support and the box-punched member;
A method for installing measuring equipment, comprising the steps of: drilling an installation hole partway through the ground using the box-punching member, installing the sensor inside the installation hole, removing the box-punching member to form a box-punching space, arranging a protective plate to cover the box-punching space, and driving anchors into at least the secondary spraying to attach the protective plate. The measuring equipment installation method described in claim 4, characterized in that in step A, a wire mesh or support rod is attached to the steel support, and the box punch member is attached to the wire mesh or support rod at the intended installation position of the sensor, thereby erecting a support unit. The measuring equipment installation method described in claim 4 or 5, wherein in step C, the anchor is a fully threaded bolt, and the anchor is removably fixed to at least the secondary spraying. The measuring equipment installation method described in claim 6, characterized in that in step C, the protective plate has a rectangular shape in plan view that is elongated in the circumferential direction of the mountain tunnel and has multiple anchor holes drilled along its periphery, and the anchors are inserted and driven into the anchor holes.