JPS6349035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shield excavation method that excavates while pumping an appropriate amount of air bubbles into a chamber facing the face of an earth pressure type excavator using a shield.

Conventionally, when excavating a water-logged sandy soil layer (including a gravel layer) with a shield excavator, the stability of the face is maintained by filling the chamber of the excavator with excavated soil. However, when the chamber is filled with earth and sand that has a large internal friction angle, the rotational resistance of the excavator's cutter increases, and in some cases, the cutter becomes unable to rotate or becomes extremely slow, resulting in a significant reduction in excavation speed. There was a problem.

One way to reduce this resistance is to inject slurry (a mixture of water and clay minerals such as bentonite and clay) into the chamber and mix it with the excavated soil, turning the excavated soil into a slurry. Conventionally, a method has been used to reduce the rotational resistance of the cutter, but since the muddy mixed soil produced by this method is treated as industrial waste, there has been a problem in that it is difficult to dispose of it.

The present invention was made to solve the above-mentioned problems, and by press-fitting air bubbles into the chamber of the face of a shield excavation machine and mixing it with excavated soil, the shear force of the mixed soil is reduced. , which reduces the rotational resistance of the cutter.

According to experimental results, when masa soil (coarse sand) and air bubbles are mixed at a volume ratio of 1:0.25, masa soil with a slump of 18 cm has such fluidity that it becomes impossible to measure the slump before mixing. I understand. Thus, the shear resistance of the soil is significantly reduced due to the mixing of air bubbles.

Furthermore, if mixed soil containing air bubbles is transported to a soil dump and left there, the air bubbles will naturally disappear and the soil will return to the state of normal excavated soil, so there is no need to treat it as industrial waste. Therefore, it is very effective in terms of pollution control.

As described above, the present invention provides a shield excavation method that reduces the rotational resistance of the cutter in the chamber of the face of a shield excavator, and is also advantageous in terms of pollution control, since there is no need to treat excavated soil as industrial waste. The purpose is to

Embodiments of the present invention will be described below with reference to the drawings.
In the figure, 1 is the ground, 1a is the shaft, 2 (see Figure 1) is the shield excavator, 2' (see Figure 2) is the shield excavator for propulsion, 3 is the chamber facing the face, and 4 is the screw discharger. The earth machine, 5 (see Figure 1) is a segment, 6 (see Figure 2) is a propulsion pipe, and 7 is a propulsion jack, which in the case of Figure 1 is interposed between the front end of the excavator 2 and segment 5. In the case of FIG. 2, the propulsion pipes 6 are arranged to be connected to the rear of the excavator 2' and are arranged so as to propel the rear end portions in the shaft 1a. Further, 8 is an earth removal conveyor installed in connection with the screw type earth removal machine 4.

Reference numeral 9 denotes a foaming device, which in the case of FIG. 1 is installed in the shaft 1a, and in the case of FIG. 2 it is installed on the ground 1.
FIG. 3 shows a schematic diagram of the structure of this foaming device 9, in which 10 is a foaming tube. An air supply pipe 11 and a liquid supply pipe 1 are connected to the foaming tube 10, and a pressure regulating valve 13 and a flow rate control valve 14 are inserted into the air supply pipe 11. 14a is a valve adjustment lever of the flow rate control valve 14.

Further, the liquid sending pipe 12 has a variable pump 16 which sucks the foaming liquid from the foaming liquid tank 15 and sends it to the foaming pipe 10.
A check valve 17 is inserted. 16a is a flow rate adjustment lever of the variable pump 16, 18 is an electric cylinder that controls this lever 16a, and 18' is an electric cylinder that controls the valve adjustment lever 14a. 19 is a foam pipe whose one end is connected to the foam pipe 10, and the other end is connected to the chamber 3 of the excavator.
It is connected inside.

Further, 20 is a displacement detector of the propulsion jack 7, and 21 is a conductor for introducing an output signal of this displacement detector 20 to a control section 22.

FIG. 4 is a circuit block diagram showing an example of this control section 22, where 23 is a rotary encoder, 24 is a rotary encoder, and 24 is a rotary encoder;
25 is a clock, 26 is a D/A converter, 27 is a controller, 28 is an electric cylinder power supply, 29 is a potentiometer, and 30 is a controller.

In the construction method of the present invention, the amount of bubbles pumped into the chamber 3 from the foaming device 9 is appropriately controlled according to the digging speed of the shield excavators 2, 2' using the above-mentioned device.

As the foaming liquid to be used in the tank 15, a surfactant or a protein-based foaming agent is suitable. ), or Escort K whose main component is partially hydrolyzed protein
(product name) etc.

Next, the construction method of the present invention using the apparatus configured as described above will be explained. In the construction method of the present invention, when excavating, the variable pump 16 is driven to feed the foaming liquid in the tank 15 into the foaming tube 10, and at the same time, air is introduced from the air pipe 11 to foam, and the foamed foam is transferred to the foaming pipe. 1
9 into the chamber 3 of the excavator 2, 2'. In this way, the excavated soil in chamber 3 becomes more fluid due to the inclusion of bubbles.
Digging performance can be improved by reducing the rotational resistance of the cutter. The excavated soil mixed with air bubbles is discharged from the screw type earth remover 4 onto the conveyor 8, and is carried outside via the conveyor 8.If this air mixed earth and sand is left in a soil dumping site, the air bubbles will naturally form. Since it disappears and becomes similar to ordinary excavated soil, there is no risk of it becoming a problem in terms of pollution control.

Further, in the construction method of the present invention, the amount of the bubbles to be pumped is appropriately controlled in accordance with the digging speed of the excavators 2 and 2'.

That is, when the displacement detector 20 detects the displacement caused by the excavation jack 7 and the signal output enters the rotary encoder 23 via the conductor 21, it is converted into a pulse, and the pulse is sent to the pulse counter 24.
The number of pulses per unit time by the clock 25 is D/A converted by the D/A converter 26, and this analog signal is sent to the controller 27.
sent to. The controller 27 controls the amount of bubbles generated by the foaming device 9 by controlling the electric cylinder power source 28 and operating the adjustment levers 14a, 16a via the electric cylinders 18, 18'.

Also, in this case, the movement of the electric cylinders 18, 18' can be adjusted proportionally to the speed by inverting the power supply to the potentiometer 29 and inputting it to the electric cylinder power supply 28 through the controller 30.

Since the construction method of the present invention is as described above, according to this construction method, it is possible to reduce the rotational resistance of the cutter in the chamber of the face of the shield excavation machine and improve the excavation performance, and it is not necessary to treat the excavated soil as industrial waste. By eliminating this, an excellent effect can be obtained, which is extremely advantageous in terms of pollution control.

[Brief explanation of drawings]

1 and 2 are elevational sectional views showing the state of ground excavation by the method of the present invention, FIG. 3 is a schematic diagram of the structure of the foaming device, and FIG. 4 is a circuit block diagram showing an example of a control section. 1...Ground, 1a...Shaft, 2...Shield excavator,
2'...Propulsion shield tunneling machine, 3...Chamber,
4... Screw earth removal machine, 5... Segment, 6... Propulsion pipe, 7... Propulsion jack, 8... Soil removal conveyor, 9... Foaming device, 10... Foaming tube, 11... Air feed pipe, 12... Liquid feed pipe, 13 ...Pressure adjustment valve, 14...Flow rate control valve, 14a...Valve adjustment lever, 15...Foaming liquid tank, 16...Variable pump, 16a...Flow rate adjustment lever, 17...Check valve, 18, 18'...Electric cylinder, 19... Foaming pipe, 20...Displacement detector, 2
DESCRIPTION OF SYMBOLS 1...Conductor, 22...Controller, 23...Rotary encoder, 24...Pulse counter, 25...Clock, 26...D/A converter, 27...Controller, 28
...Electric cylinder power supply, 29...Potensiometer, 30...Controller.

Claims (1)

[Claims] 1. A shield excavation method characterized in that air bubbles are force-fed to the front face of a shield excavation machine and mixed with excavated soil, and the amount of air bubbles fed is controlled according to the amount of thrust of the shield excavation machine. .