JPH0448162B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the amount of voids generated at the top when constructing a secondary concrete lining for forming a tunnel.

[Conventional technology]

Generally, when constructing a secondary lining for a tunnel, a formwork is installed inside the tunnel and concrete is poured into the gap between the formwork and the tunnel, but some gap remains at the top. It is normal to do so.

Therefore, the amount of voids must not exceed a permissible value below the predetermined concrete thickness.

Therefore, methods for managing the top void of the secondary lining include a method of detecting the pressure due to the weight of concrete placement, and a method of detecting the winding thickness using a sensor that detects the height of concrete placement.

[Problem that the invention seeks to solve]

However, although the former method is extremely effective in determining the effective pressure of concrete acting on the formwork, it is impossible to directly determine the amount of voids generated at the top, and the latter method is The method is to install sensors at several locations at the top of the tunnel and detect the amount of voids by knowing the concrete placement situation, but this method has the problem of being uneconomical because the sensors must be buried. There is.

[Means for solving problems]

In view of the problems of the prior art as described above, the present invention has been made with the objective of providing a method for detecting the amount of voids in a secondary lining that can accurately determine the amount of voids generated in the secondary lining. Its structure is that when constructing the secondary lining of a tunnel, a formwork is installed in the tunnel, and the top of the concrete is detected from the inside of the top of the formwork toward the top of the tunnel, etc. An appropriate number of level switch electrode rods equipped with electrodes, uniform thickness, and arbitrary length are inserted variably, and the height from the formwork to the top of the tunnel etc. is measured using the electrode rods as a scale, and The thickness of the secondary lining concrete is set by the insertion length of this electrode rod, and the insertion length of the electrode rod at that time is determined by detecting the top of the concrete to be cast by the electrode of the electrode rod. The method is characterized in that the amount of air at the top of the secondary lining is detected based on these measured values.

[Effect]

That is, the present invention uses, for example, a capacitive level switch for detecting the concrete casting surface, and inserts an appropriate number of the electrode rods from the inside of the top of the formwork toward the top of the tunnel with a variable insertion length. concrete is placed, the change in capacitance is caught by the electrode rod, and an alarm lamp is lit via a relay to detect the amount of void.

〔Example〕

Next, an example of implementation of the method of the present invention will be explained with reference to the drawings.

Figure 1 shows the level switch installed on the formwork K. The level switch is composed of an electrode rod A and an amplifier device B containing an amplifier inside, and the electrode rod A has an electrode D fixed to its tip. Insulated rod 1
The pipe 2 has a winding thickness scale. 3 is a suitable number of bolts fixed to the top of the formwork K; 4 is a rubber packing with a through hole 5 in the center for inserting the electrode rod A, and the bolt 5 is fitted around the periphery; 6 is a slide flange; A seal cylinder 7 is fixed to the seal cylinder 7 and a seal material 8 is arranged thereon, and a lock bolt 9 is attached to the seal cylinder 7.
0 is fixed, and through holes 11, 12, 13 similar to the through holes 5 of the rubber packing 4 are provided in the center of the slide flange 6, seal cylinder 7, and mounting cylinder 10, and the slide flange 6 is fitted onto the bolt 3. to be dressed,
The nuts 14 are screwed onto the bolts 3 and tightened, and the slide flange 6 is attached to the formwork K with the rubber packing 4 interposed.
It has become established.

Then, the electrode rod A passes through the mounting tube 10, the seal material 8, the seal tube 7, the slide flange 6, the rubber packing 4, and the formwork K, and enters the gap R between the formwork K and the tunnel T. It is now possible to insert it.

Note that the amplifier device B is detachably attached to the electrode rod A.

Next, a procedure for managing the top void of the secondary lining concrete using the above-mentioned level switch device will be explained.

(1) Determine the installation position of the winding thickness detection part in the formwork K. If the segments that make up the tunnel are steel segments, select several locations in the longitudinal direction where the ribs or joints can be avoided. .

(2) Drill an electrode rod insertion hole Ka at the above mounting position,
Install the rubber packing 4 and slide flange 6.

(3) After cleaning the formwork K and applying a release agent,
As shown in Figure a, the electrode rod A is inserted to the top of the tunnel, and the height H from the formwork to the top of the tunnel is measured.

(4) Slide the electrode rod A and attach it to the mounting tube 1 with the lock bolt 9 at the desired height position (scale H1).
0, and as shown in FIG. 2b, set the amplifier device B and connect the amplifier to the alarm AL.

(5) Concrete is poured in the state of (4) above, and when the top of the concrete reaches electrode D at the tip of electrode rod A, as shown in Figure 2c, electrode D detects this. , the alarm AL lamp lights up via the amplifier device.

(6) Now, as shown in Fig. 2d, when the insertion length of electrode rod A is increased to H2, it becomes detectable again and the lamp of alarm AL goes out.

(7) By performing the operations (4) to (6) above, it is possible to grasp the concrete pouring condition, but it is assumed that the planned amount of concrete has now been poured and the condition is as shown in Figure 2 e. Then, this time, reverse the electrode rod A to the alarm.
Pull it out until the AL lamp lights up. The position where the light is lit at this time is the top position of the poured concrete, and the measured value at that time is the actual thickness H3.

(8) Obtain H and H3 by the above operations, and calculate the void amount ΔH=H−H3. If ΔH is greater than the allowable value, pour more concrete into the void.

(9) When the measurement of the actual winding thickness is completed and it is within the allowable value, as shown in Figure 2 f, the amplifier device B
Remove the electrode rod A by loosening the lock bolt 9 and pull out the electrode rod A. In order to prevent concrete from flowing out from the electrode rod insertion hole Ka, insert a closing pin P into the insertion hole to close it, as shown in Fig. 2g. Insert and complete all tasks.

In the above, the lamp of the alarm AL was used as a method for confirming whether or not the level switch was detected, but the operation indicator lamp normally attached to the amplifier may also be used.

Further, the state in which the closing pin P is attached is as shown in FIG.

〔Effect of the invention〕

As described above, the present invention has the following advantages over conventional methods.

(1) Not only can you see the flow of concrete during pouring, but you can also measure the thickness of the concrete roll at any location during pouring.

(2) The electrode rod can be easily installed even in a narrow space, and the electrode rod itself can be used as a scale, so measuring the height from the formwork to the top of the tunnel can be done just as easily as measuring the concrete wrapping thickness. .

(3) By measuring the final thickness of concrete, it is possible to accurately determine the amount of voids.

(4) After the secondary lining is completed, the electrode rod is removed and the electrode rod insertion hole provided in the formwork is closed with a closing pin, so that the sensor does not remain in the concrete.

(5) Since electrode rods can be used repeatedly, economical efficiency increases as the construction length and number of times they are used increases.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the level switch installed on the formwork, Figures 2a to 2f are diagrams showing the procedure for managing the voids at the top of the secondary lining concrete, and Figure 3 is a cross-sectional view of the level switch installed on the formwork. FIG. 3 is a cross-sectional view of the lining with the closing pins attached after concrete pouring. A... Electrode rod, B... Amplifier device, D... Electrode, AL
...Alarm, K...Formwork, T...Tunnel, 6...Slide flange, 7...Seal tube, 8...Seal material, 9...
Lock bolt, 10... Lock bolt mounting tube, 1
4...Natsuto.

Claims (1)

[Claims] 1. When constructing the secondary lining of a tunnel, a formwork is installed in the tunnel, and an electrode is provided at the top end of the formwork to detect the top of the concrete, pointing from the inside of the top of the formwork toward the top of the tunnel, etc. Insert an appropriate number of level switch electrode rods of uniform thickness and arbitrary length with variable insertion length, use the electrode rods as a scale to measure the height from the formwork to the top of the tunnel, etc. The thickness of the secondary lining concrete is set by the insertion length of the rod, while the top of the concrete to be cast by the electrode of the electrode rod is detected and the insertion length of the electrode rod at that time is measured. A method for detecting the amount of empty space in a secondary lining, which is characterized in that the amount of empty space at the top of the secondary lining is detected based on these measured values.