JP7565310B2 - Cover material - Google Patents

Description

The present invention relates to a cover member used for measuring internal displacement, for example, in mountain tunnel construction work.

In mountain tunnel construction work, displacement measurements inside the tunnel are carried out as part of daily management in order to understand the behavior of the ground. Measurement points for measuring displacement inside the tunnel are set at five points per cross section, with measurements taken at 10m intervals (20-30m depending on the soil cover and construction progress). Measurements must be taken at least twice a day immediately after excavation. Previously, this measurement was carried out manually using a total station, with surveying reflective sheets (simple targets) set at the measurement points.

In recent years, the frequency of internal displacement measurements has been increased from the standard in order to understand the behavior of the ground in more detail. However, increasing the frequency of measurements poses the issue of increased labor required for measurements, which are still done manually. Therefore, to address this issue, automatic measurements are being adopted, using surveying prisms rather than surveying reflective sheets, and automatic collimation total stations.

On the other hand, surveying prisms are essential for automatic measurement, but there are concerns that they may be damaged by blasting used during excavation or flying debris such as flying stones, so efforts are being made to remove them except when making measurements and attach them only when making measurements.
While this innovation eliminated the risk of damage from blasting or flying debris such as flying stones, it still required the effort of setting up a surveying prism for each measurement, which was an issue.

Japanese Patent Application Publication No. 5-99670

Thus, the present invention has been devised to address the above-mentioned conventional problems, and has an object to provide a cover member which protects surveying targets and the like as protected objects from damage sources during tunnel construction, such as blast debris caused by blasting, and which allows excavation by blasting with the protected object attached without the need to remove it for each blasting, thereby making it possible to carry out excavation by blasting with the protected object attached, thereby keeping the measurement position constant and enabling accurate displacement measurement inside the tunnel, and which prevents damage to the surface of the protected object due to splashes of sprayed concrete and the like adhering to the protected object, and furthermore, which allows the protected object to be installed in the vicinity of the face, making it possible to measure displacement early after excavation, thereby shortening the tunnel construction period and enabling construction work to be carried out efficiently.

The present invention relates to
A displacement measuring device for a tunnel inner wall, in which a survey target is set on the inner wall of a tunnel being excavated, a measuring wave is emitted from a surveying instrument set on the tunnel entrance side toward the survey target, and the reflected wave of the measuring wave from the survey target is detected to obtain information on the displacement of the interior of the tunnel caused by the excavation of the tunnel,
The tunnel inner wall displacement measuring device has a cover member that covers and protects the survey target from blasting debris generated by blasting the tunnel face,
The cover member has a measurement wave measurable opening formed on the tunnel entrance side, through which the measurement wave emitted from the tunnel entrance side can be measured, and is structured to cover the survey target in a non-contact state;
The structure for covering the survey target in a non-contact state is such that the upper surface of the cover member extends in a direction parallel to the tunnel excavation direction to form a substantially rectangular shape, and is formed on a downward slope from the end face on the tunnel entrance side to the end face on the tunnel face side, and both side surfaces that bend downward from the widthwise end face of the upper surface are configured in a triangular shape with a downward slope from the end on the tunnel entrance side to the end on the tunnel face side, and the upper surface and both side surfaces of the above-mentioned configuration are configured to be able to deflect blasting debris scattered by blasting, thereby suppressing damage to the cover member, and preventing damage to the covered survey target, and the opening shape of the measurement wave measurable opening is substantially trapezoidal, and the both side surfaces are expanded outward from both end faces of the substantially rectangular upper surface and bent downward.
It is characterized by:
or
A plurality of the survey targets are attached to the inner wall surface of the tunnel being excavated.
It is characterized by the above.

According to the present invention, surveying targets and the like are protected as protected objects from damage sources during tunnel construction, such as blast debris caused by blasting, and excavation by blasting can be carried out with the protected objects attached without the need to remove them for each blasting. This allows the measurement position to be constant, making it possible to perform accurate displacement measurements inside the tunnel. It also prevents damage to the surface of the protected object caused by splashes of sprayed concrete and the like adhering to the protected object. Furthermore, since the protected object can be installed near the face, it becomes possible to perform displacement measurements early after excavation, which has the effect of shortening the tunnel construction period and enabling construction work to be carried out more efficiently.

FIG. 1 is a schematic diagram (1) showing the configuration of a target tunnel in which an object to be protected (e.g., a survey prism 2) is placed. FIG. 2 is a schematic diagram (2) showing the configuration of a target tunnel in which an object to be protected (e.g., a survey prism 2) is placed. 1 is a schematic diagram (3) showing the configuration of a target tunnel in which an object to be protected (e.g., a survey prism 2) is placed. FIG. 11 is a diagram showing an embodiment in which an object to be protected (e.g., a surveying prism 2) is covered with a cover member.

The present invention will now be described with reference to examples.
The displacement measuring device for the inner wall surface of a tunnel according to the present invention is used, for example, at a location during the construction of a tunnel. On the inner wall surface of a tunnel excavated by blasting, multiple surveying targets are installed, and measuring waves are emitted toward the surveying targets, and a surveying instrument 1 (such as a total station) detects and measures the reflected waves from the measuring waves. Then, by measuring the detected reflected waves and calculating the measured values, it is possible to obtain information on the displacement of the interior of the tunnel caused by the excavation of the tunnel.

Figure 1(a) is a diagram showing the installation location of a survey target when measuring the internal displacement of a tunnel, for example, in mountain tunnel construction work. Also, Figure 1(b) is a schematic diagram showing the side view of the target tunnel with the survey target placed.

One example of the survey target is a survey prism 2. As explained in the Background section, the measurement points for measuring internal displacement are basically five per cross section, and are set at 10 m intervals (20 to 30 m depending on the soil cover and construction progress). In addition, measurements must be taken at least twice a day immediately after excavation.

When measuring the air displacement inside a tunnel, the survey prisms 2 are installed at five locations (measurement points) per cross section as a rule, but depending on the construction method and various conditions such as the ground conditions and location conditions of the target tunnel, the number of locations per cross section can be three.

As shown in Figure 1(b), the total station serving as the surveying instrument 1 is installed at the tunnel entrance, about 50 to 100 m away from the tunnel face. As described above, the surveying instrument 1 can measure the air displacement inside the tunnel by having the surveying prism 2 reflect the measurement wave emitted from the surveying instrument 1 and detecting the reflected wave.

Here, measurements of tunnel internal displacement, especially initial values of internal displacement immediately after excavation, must be performed as early as possible at a location close to the tunnel face, for example, approximately 3 m from the face. If the start of measurements is delayed, the displacement (behavior of the ground and shoring) will progress, and the amount of information that can be obtained will decrease accordingly. Furthermore, it is important to standardize the cross-sectional location and frequency of displacement measurements in order to obtain the information necessary to consider setting appropriate management standards and to reflect this in the design and construction of the tunnel.

Conventionally, even if a surveying prism 2 was installed, there was concern that it could be damaged by blasting used during excavation or by flying stones and other blast debris, so the surveying prism 2 was removed except when making measurements, and the surveying prism 2 was attached each time a measurement was made. This meant that the effort of installing the surveying prism 2 was required for each measurement, and it was difficult to perform measurements immediately after excavation.

The tunnel inner wall displacement measuring device according to the present invention is configured such that multiple surveying targets (surveying prisms 2) are installed on the tunnel inner wall as objects to be protected, and each surveying prism 2 is covered with a cover member 3. In other words, by covering the surroundings of the surveying prism 2 except for the part that opens to the tunnel entrance side with the cover member 3 without contacting the surveying prism 2, the surveying prism 2 is protected from damage-causing objects that could damage it, and there is no need to remove the surveying prism 2 that was installed midway through the construction of the tunnel.

Possible causes of damage here include construction machinery such as backhoes, and blast debris generated after excavation by blasting. For example, heavy machinery working inside a tunnel may come into contact with the survey prism 2 and damage it, or objects such as pebbles kicked up by a conveyor belt or transport vehicle may collide with the survey prism 2 and damage it. In the following embodiment, blast debris generated after excavation will be described in detail.

The cover member 3 has a measuring wave measurable opening 4 formed on the tunnel mouth side. Figures 4(a) and 4(b) show an embodiment in which a survey prism 2 is installed on the inner wall surface of a tunnel and the survey prism 2 is covered by the cover member 3 in a non-contact manner. As can be seen from Figures 4(a) and 4(b), the cover member 3 has an opening on the tunnel mouth side, i.e., a measuring wave measurable opening 4 is formed, while the face side is not open and is closed in contact with the inner wall surface of the tunnel. The cover member 3 has a gentle downward slope from the opening end of the measuring wave measurable opening 4 toward the face side. This allows the blasting debris flying from the face side to be deflected, minimizing damage to the cover member 3 and thereby preventing damage to the survey prism 2. Here, there is no limitation on the specific shape of the cover member 3, but it is important that the measuring wave measurable opening 4 is provided and that the exterior of the survey prism 2 is covered in other places. There are also no limitations on the material that the cover member 3 is made of, but it must be made of a material that will not be damaged even if it is hit by flying blast debris.

It is generally believed that the cover member 3 is made of metal material, but in that case, when bending it three-dimensionally to cover the exterior of the survey prism 2, the bent parts are bent at an angle. Therefore, the cover member 3 has a shape as shown in FIG. 4, that is, of the three faces that cover the survey prism 2 when the cover member 3 is installed, the face (top face) facing the inside of the tunnel is approximately rectangular, and both side faces are approximately triangular, and since both side faces are approximately triangular, the approximately rectangular face often has a downward slope from one end in the longitudinal direction (the end that faces the tunnel entrance in the installed state) to the other end in the longitudinal direction (the end that faces the tunnel face in the installed state). Furthermore, the both side faces may be formed to slightly expand outward from the approximately rectangular face so that the opening shape of the measurement wave measurable opening 4 is approximately trapezoidal.

The cover member 3 is attached to the concrete part of the inner wall of the tunnel, for example, by means of bolts or other fasteners, without contacting the survey prism 2. In FIG. 4, the cover member 3 is fixed at two points on both sides by fasteners. However, this fastening method is not limited, and the cover member 3 can be more firmly fixed at three points in total by also fastening the point on the opposite side of the measurement wave measurable opening 4. In this way, there are no limitations on the number of fastening points or fastening points for fastening the cover member 3 to the wall, and any fastening method can be used as long as the survey prism 2 is not damaged and is protected by excavation caused by blasting. Furthermore, in addition to fastening the cover member 3 using fasteners, other methods such as fastening it to the support with magnets or welding can be considered.

As described above, excavation can be carried out by blasting with the surveying prism 2 installed on the inner wall of the tunnel, and displacement inside the tunnel can be measured with a surveying instrument such as a total station placed on the tunnel entrance side while protecting the surveying prism 2 from blasting debris such as flying stones. In other words, in the past, it was necessary to remove the surveying prism 2 from the inner wall of the tunnel each time blasting was carried out to prevent damage to the prism, but by covering the surveying prism 2 with the cover member 3, damage is prevented, and the cover member 3 has an opening 4 for measuring measuring waves, and because the opening on the tunnel entrance side is shaped in such a way that it is possible to measure displacement without blocking or interfering with the measuring waves from the total station.

In particular, according to the present invention, even immediately after excavation by blasting, the survey prism 2 can be attached near the face, and since there is no need to remove it, displacement measurement can be performed quickly, and there is no delay in starting measurement, and consistent measurements can be performed at the same position and under the same conditions. Therefore, the accurate information obtained can be used to consider setting appropriate management standards, and since accurate information can be obtained while reducing the labor required for reinstalling the prism, construction can be carried out more safely.

Next, an embodiment of displacement measurement using the displacement measuring device for the inner wall surface of a tunnel will be described with reference to Figs.
After excavation by blasting at a section in the middle of tunnel construction, survey prisms 2 are installed at five measurement points per cross section. In this embodiment, one survey prism 2 is installed near the top end of the tunnel inner wall, and two at the top and bottom of each of the left and right side walls, for a total of five measurement points. Note that the number of measurement points is set taking into consideration the excavation method and expected behavior of the ground, and is not limited to the five measurement points in this embodiment.

Then, a cover member 3 is attached to each of the installed survey prisms 2 using a connector such as a bolt. At this time, the cover member 3 is attached so that the open surface, i.e., the surface on which the measurement wave measuring opening 4 is formed, faces the tunnel entrance.

After that, a measurement wave is emitted from the total station installed at the tunnel entrance, and the measurement wave is reflected by the survey prism 2. The reflected wave is detected by the surveying instrument 1 in the total station, and measurements are made to obtain the displacement inside the tunnel. The frequency of measurements is more than twice a day immediately after excavation.

In this way, the survey prism 2 can reflect the measurement wave as a reflected wave even when covered with the cover member 3. In other words, since the cover member 3 has a measurement wave measurable opening 4 formed therein, it is possible to perform measurements without having to remove the cover member 3 each time a measurement is performed.

After the measurements are made, the debris generated by the blasting is removed outside using a prescribed method. Then, to prevent the excavated face from collapsing, sprayed concrete is sprayed onto the face and other areas near the face to protect it. If the surface of the survey prism 2 becomes soiled by splashes of sprayed concrete, problems will arise such as no reflected waves from the total station (surveying instrument 1), which will have a negative effect on displacement measurement.

Conventionally, splashes of sprayed concrete and the like would often adhere to the surface of the surveying prism 2, and to deal with this, it was necessary to remove the surveying prism 2 every time sprayed concrete was applied, or to remove the splashed dirt from the surveying prism 2, which took time and effort. In the present invention, a cover member 3 is attached to each surveying prism 2, so that the surveying prism 2 can be prevented from being soiled even when sprayed concrete is applied. Furthermore, it also serves to prevent dust generated by blasting or the operation of large heavy machinery from adhering to the surveying prism 2 and causing soiling. This solves the conventional problem, which also results in a significant reduction in work time.

Then, the tunnel is excavated again by blasting, but in the past, the survey prism 2 was removed from the inner tunnel wall after the displacement measurement. In contrast, in the present invention, the survey prism 2 is left in place and the cover member 3 is attached to cover the survey prism 2, so blasting can be performed without removing it.

Since there is no need to remove the survey prism 2 except when making measurements, as in the past, labor can be reduced, and the time required to attach and remove the survey prism 2 for each blasting is reduced, which shortens construction time.

Then, the survey prism 2 for the next measurement point is installed at an interval of about 10 to 20 m from the measurement point where the survey prism 2 was installed (see Figure 1 (b)). Note that the interval between measurement points depends on the ground conditions of the target tunnel, for example, if the ground is weak, the measurement points are installed at intervals of several meters.

In the same manner as described above, a cover member 3 is attached to each survey prism 2 at the next measurement point. In this case, the cover member 3 is attached so that the open surface of the cover member 3, i.e., the surface on which the measurement wave measurable opening 4 is formed, faces the tunnel mouth. Then, a measurement wave is emitted from a total station installed on the tunnel mouth side, the survey prism 2 reflects the measurement wave, and the total station detects this reflected wave to calculate and measure the displacement inside the tunnel (see FIG. 2).
The total station is installed 50 to 100 m away from the tunnel face, and is moved so that the distance from the tunnel face does not exceed 100 m.

As the excavation progresses, the cover member 3 is removed at points where there is no longer any impact from blasting or blast debris such as flying stones. That is, as can be seen from Figure 3, the cover member 3 is removed from the survey prism 2 installed on the mine mouth side of the total station, and the cover member 3 is attached to the survey prism 2 between the face and the total station.

In order to determine whether the displacement inside the tunnel has converged, the survey prism 2 with the cover member 3 removed is left installed on the inner wall of the tunnel. This makes it possible to measure the displacement inside the tunnel in the direction of the tunnel entrance by rotating the total station 180 degrees horizontally. The removed cover member 3 can also be used again for a newly installed survey prism 2, which reduces costs as there is no need to prepare the same number of cover members 3 as the survey prisms 2. After it is confirmed that the displacement inside the tunnel has converged, the lining concrete is constructed.

Incidentally, the cover member 3 may also be left attached to the survey prism 2 installed on the tunnel entrance side of the total station without being removed. In this case, the total station must emit survey waves from the back of the tunnel toward the tunnel entrance, i.e., in the opposite direction to the measurement procedure described so far, to measure the displacement. In that case, the cover member may be attached with the measurement wave measurable opening 4 facing the back of the tunnel. This makes it possible to protect the survey prism 2, particularly the survey prisms 2 installed on the left and right side walls of the tunnel inner wall, from flying debris such as stones generated by conveyor belts and transport vehicles when transporting the rubble from the tunnel entrance.

By repeating this procedure, it is possible to obtain accurate and rapid information on displacement measurements inside the tunnel. Then, by reflecting the information on the displacement measurements in the construction of the target tunnel, appropriate lining work can be carried out.

In the above embodiment, the object to be protected by the cover member 3 is the survey target (e.g., the survey prism 2), but the object to be protected by the cover member 3 is not limited as long as an opening is formed on one side of the tunnel excavation direction at a location during tunnel formation, the cover member 3 is attached to the inner wall of the tunnel so as to cover the object to be protected without contacting the object to be protected, and the cover member 3 is configured to protect the object to be protected from damage sources. For example, in the case where a display means (e.g., a monitor) that displays a color or image according to a predetermined displacement level based on the measurement result corresponding to the survey target is installed near the survey target on the inner wall of the tunnel for the purpose of making it easier for workers to visually recognize the displacement measurement result by the displacement measurement device on the inner wall of the tunnel as described above, that is, for the purpose of making it visible, the display means can also be used as the object to be protected, and the cover member 3 can be applied.

1 Surveying instrument 2 Surveying prism 3 Cover member 4 Measurement wave measurable opening

Claims (2)

A displacement measuring device for a tunnel inner wall, in which a survey target is set on the inner wall of a tunnel being excavated, a measuring wave is emitted from a surveying instrument set on the tunnel entrance side toward the survey target, and the reflected wave of the measuring wave from the survey target is detected to obtain information on the displacement of the interior of the tunnel caused by the excavation of the tunnel,
The tunnel inner wall displacement measuring device has a cover member that covers and protects the survey target from blasting debris generated by blasting the tunnel face,
The cover member has a measurement wave measurable opening formed on the tunnel entrance side, through which the measurement wave emitted from the tunnel entrance side can be measured, and is structured to cover the survey target in a non-contact state;
The structure for covering the survey target in a non-contact state is such that the upper surface of the cover member extends in a direction parallel to the tunnel excavation direction to form a substantially rectangular shape, and is formed on a downward slope from the end face on the tunnel entrance side to the end face on the tunnel face side, and both side surfaces that bend downward from the widthwise end face of the upper surface are configured in a triangular shape with a downward slope from the end on the tunnel entrance side to the end on the tunnel face side, and the upper surface and both side surfaces of the above-mentioned configuration are configured to be able to deflect blasting debris scattered by blasting, thereby suppressing damage to the cover member, and preventing damage to the covered survey target, and the opening shape of the measurement wave measurable opening is substantially trapezoidal, and the both side surfaces are expanded outward from both end faces of the substantially rectangular upper surface and bent downward.
A displacement measuring device for the inner wall of a tunnel.
A plurality of the survey targets are attached to the inner wall surface of the tunnel being excavated.
2. The tunnel inner wall displacement measuring device according to claim 1.