JPH0574420B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a lining method in which lining material such as cement is sprayed to prevent wall collapse of excavated ground in tunnel construction, etc., and a lining used to carry out the method. It is related to the device. There are two types of lining methods: the wet method and the dry method. The latter dry method is a construction method in which the dry powder material described above is pumped into a transportation pipe together with compressed air, and a liquid is injected into the transportation pipe before the discharge port. The present invention relates to the latter dry construction method. (Prior art) In the conventional dry construction method, in order to prevent the lining material transport pipe from being blocked, the dry powder material is pumped together with compressed air at a speed of approximately 30 m/sec or more, and near the discharge port, the As shown in Fig. 5, the liquid supplied through the water pipe d is injected into the dry powder material through several nozzle holes c provided on the inner surface of a hollow annular body b provided in the middle of the transport pipe a. The liquid was sprayed onto the wall. (Problem to be solved by the invention) However, in this conventional method, the nozzle hole c
Because the liquid was sprayed out in a straight line, it was difficult for the liquid to spread over the entire dry powder material.As a result, the liquid turned into dust during spraying, causing a worsening of the working environment in tunnel construction, etc. I was getting used to it. Furthermore, if the dry powder materials, especially cement and fine aggregate, cannot be sufficiently mixed with the liquid, a highly viscous mortar will be formed, resulting in the problem that the sprayed material that does not adhere to the wall will bounce back. In addition, conventional liquid volume control was carried out by the worker observing the adhesion of the sprayed material to the wall surface and operating a water volume adjustment valve (not shown) at hand. It was difficult to obtain the cement ratio (the amount of liquid per unit cement). As a result, there was a problem that the strength of the finished shotcrete varied widely. (Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and in the lining method in which the lining material is pumped by air pressure and sprayed onto the wall surface, the lining material is transported through a pipe. This is a lining method in which liquid is sprayed at a wide angle onto the lining material using a fan-shaped spray nozzle and a straight nozzle installed in the middle of the lining. A fan-shaped spray nozzle and a straight forward nozzle installed in the middle of the material transport pipe spray and supply liquid to the lining material at a wide angle, and a fixed-volume type is supplied by an induction motor operated via a frequency regulator. This is a lining method that controls the supply amount of the liquid to a desired set value by controlling the rotation of the pump.It also includes a sprayer that feeds the lining material into the transport pipe together with compressed air, and a sprayer that feeds the lining material into the transport pipe along with compressed air. It is equipped with a fan-shaped spray nozzle and a linear nozzle provided, a constant volume pump that supplies liquid to these nozzles, an induction motor that drives this constant volume pump, and a frequency regulator that controls the rotation of this induction motor. The lining device is characterized by: (Function) As mentioned above, in the construction method of the present invention, the fan-shaped spray nozzle and the straight nozzle provided in the middle of the lining material transport pipe are used to spray and supply liquid to the lining material at a wide angle. The dry powder material mixes well with the liquid, reducing the amount of dust generated during spraying and reducing the amount of sprayed material that bounces off rather than sticking to the wall. In particular, in the present invention, since the fan-shaped spray nozzle and the straight nozzle are used in combination, the above-mentioned effects are promoted. Furthermore, in the present invention, the rotation of the fixed displacement pump is controlled by an induction motor driven via a frequency regulator, so that the amount of liquid supplied is controlled to a desired set value. The water-cement ratio is always close to the design value.
Therefore, the finished shotcrete becomes homogeneous, and variations in strength are reduced. (Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3. In the figure, 1 is the wall surface on which the lining material will be sprayed, 2 is the hopper for the dry powder material of the lining material, and 3
is a belt conveyor conveying the material discharged from the hopper 2. In this embodiment, a sprayer 6 is provided which is connected to the delivery end of the belt conveyor 3 and sends the dry powder material into the transport pipe 5 together with the compressed air of the compressor 4, and is located near the discharge port 5a of the transport pipe 5. A plurality of fan-shaped spray nozzles 7 as shown in FIG. 2 and FIG.
A straight nozzle 8 is provided in between, penetrating the pipe wall of the transport pipe 5. In this embodiment, as shown in FIG. 2, three fan-shaped spray nozzles 7 are provided on the same circumference at the location A shown in FIG. A straight nozzle 8 is provided so that water can be injected into the transport pipe 5 from a total of six nozzles 7 and 8. These fan-shaped spray nozzles 7 and straight nozzles 8
are connected to a constant displacement pump 10 via a liquid supply pipe 9, and this pump 10 is connected to an induction motor 1.
1, and the number of revolutions of the induction motor 11 can be set to a desired value by a frequency adjuster 12. 12a is a dial for adjusting the frequency, and this dial 12a
If the frequency is changed by operating the induction motor 11, the rotation speed of the induction motor 11 will also change, and as a result, the discharge amount of the constant displacement pump 10 can be changed in proportion to the rotation speed. Therefore, if the frequency corresponding to each discharge amount of the pump 10 is calculated in advance, the dial 12
Since a desired discharge amount can be obtained by adjusting a, the water-cement ratio of shotcrete can be set accurately. Next, experimental results according to the present invention and comparison results with conventional construction methods will be explained.

【table】

[Table] * When the surface water content of fine aggregate was 6%, the water supply rate was 9.03/min and the water pressure was 30.0Kg/ ^cm2 . (c) Experimental results (C-1) Material rebound test A concrete plate (4 m wide x 2 m long x 0.2 m thick) was used as the spraying surface, and the amount of spray per time was approximately 0.1 m ³ (≒240 kg) (2 m wide). ×Vertical 1m×
The experiment was conducted with a thickness of 0.05 m). Rebound rate (R%) is the attached weight (AKg)
The rebound weight (BKg) was measured and calculated from R=B/A+B×100 (%).

[Table] Conventional method - A water injection ring with six conventional water injection holes was installed 3 m before the exit of the transport pipe. The construction method of the present invention - A water injection ring was used in which three fan-shaped spray nozzles and three straight nozzles were alternately arranged on the same circumference at one location 3 m before the outlet of the transport pipe. (C-2) Dust amount measurement The dust amount was measured under the conditions of a tunnel cross section of 40 m ² and ventilation rate of 600 m ³ /min. The measurement location was 1.5m above ground level near the center of the tunnel, 5m behind the spraying point. Measuring instrument KANO
−MAX (low volume sampler)

[Table] (C-3) Concrete strength test Specimens were taken from shotcrete by boring and compressive strength tests were conducted. The compression test results on the 28th were as follows.

[Table] (Effects of the invention) As mentioned above, according to the present invention, the amount of dust during concrete spraying is reduced to approximately 1/3, so
It can improve the working environment for tunnel construction, etc. In addition, the amount of lining material splashed back is reduced, which reduces material waste and helps improve the working environment. Further, according to the present invention, it is possible to obtain the effects that the shotcrete becomes homogeneous and its strength increases as a whole.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the device of the present invention used in the method of the present invention, Fig. 2 is a sectional view of its main parts, Fig. 3 is a sectional view of its fan-shaped spray nozzle, and Fig. 4 is a schematic diagram of the device used in the conventional method. Perspective view of the water injection ring section, No. 5
The figure is a partial sectional view. 1... Wall surface, 2... Hopper, 3... Belt conveyor, 4... Compressor, 5... Transport pipe, 6... Spray machine, 7... Fan-shaped spray nozzle,
8... Straight nozzle, 9... Liquid feed pipe, 10...
Constant displacement pump, 11... Induction motor, 12...
Frequency adjuster.

Claims (1)

[Claims] 1. In a lining method in which lining material is pumped by air pressure and sprayed onto a wall surface, a fan-shaped spray nozzle and a straight nozzle installed in the middle of a lining material transport pipe spray liquid onto the lining material at a wide angle. A lining method characterized by spraying and supplying. 2 In the lining method in which lining material is pumped by air pressure and sprayed onto the wall surface, a fan-shaped spray nozzle and a straight nozzle installed in the middle of the lining material transport pipe are used to spray and supply liquid to the lining material at a wide angle. A lining method characterized in that the supply amount of the liquid is controlled to a desired set value by controlling the rotation of a constant displacement pump by an induction motor operated via a frequency regulator. 3. A sprayer that sends the lining material into the transport pipe together with compressed air, a fan-shaped spray nozzle and a straight nozzle installed in the middle of this transport pipe, a fixed volume pump that supplies liquid to these nozzles, and this fixed volume pump. A lining device comprising an induction motor that drives a pump and a frequency adjuster that controls the rotation of the induction motor.