JPH0633715B2 - Shield excavation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention performs excavation while pumping an appropriate amount of bubbles into the face portion of the earth pressure excavator using a shield and the chamber facing the face face. This relates to the shield excavation method.

(Prior art and its problems) When excavating a gravel soil layer (including a gravel layer) that has been flooded by a shield machine, the stability of the cutting face is attempted to be maintained by filling the chamber of the machine with excavated soil. . However, in reality, it is very difficult to keep the excavated soil in the chamber, and it is difficult to suppress the inflow of groundwater into the chamber. is there. Also, when the chamber is filled with earth and sand with a large internal friction angle, the rotation resistance of the cutter of the excavator becomes large, and in some cases the cutter cannot rotate or it becomes extremely bad, resulting in a remarkable excavation speed. There was a problem of lowering.

Therefore, as a method to prevent the inflow of groundwater into the chamber and to reduce the resistance of cutter rotation, a mud material (a mixture of water and clay minerals such as bentonite) is injected into the chamber and mixed with the excavated soil. A method has heretofore been adopted in which the excavated soil is muddyed to prevent the groundwater from flowing into the chamber and to reduce the rotational resistance of the cutter. However, even with this method, when the water pressure of the face is high, or the aquifer containing large gravel cannot be sufficiently stopped, inflow of groundwater into the chamber may not be prevented. In addition, the mud-like mixed soil produced by this method has a high PH, and because of the mud-like shape, it is difficult to dispose of it, and the secondary pollution of construction occurs due to the disposal.

There is also known a method in which a mixed fluid composed of water, a foaming agent and air is supplied into the pressure chamber, and the mixed fluid is mixed with the cut earth and sand to pressurize the face of the face. (Kaisho 50-103129).

However, even with this method, it was not sufficient to suppress the groundwater from the face, and there was a limit to the stabilization of the face.

(Means for Solving the Problems) The present invention has been made to solve the problems as described above, and pumps bubbles that are hard to disappear even if they fit into the face of the cutter of the shield machine, even if they meet with water, By invading air bubbles into the ground, it creates a pressured state that is more effective than the normal pressured construction method, prevents groundwater from mixing into the cutting face, stabilizes the cutting face, and also sends bubbles to the chamber by another system. By mixing it with the excavated soil, reducing the shearing force of the mixed soil to reduce the rotational resistance of the cutter, and filling the mixed soil in the chamber and the screw to further stabilize the face. This is to give the excavated soil non-permeability and non-permeability.

That is, for example, according to the experimental results, the gravel content is 82%.
When the foam material is used in the ground, the use of the air bubble amount of about 1/1000 of the air amount used in the normal air pressure construction method has a sufficient air pressure effect.

Further, it is understood that when the masa soil (coarse sand) and the bubbles are mixed at a volume ratio of 1: 0.25, the masa soil of 7 cm of slumb has fluidity such that slamb cannot be measured before mixing. Thus, the mixing of air bubbles significantly reduces the shear resistance of soil.

In addition, if mixed soil mixed with bubbles is transported to the dump site and left there, the bubbles will disappear naturally and the state will return to normal excavated soil. It has the advantage of not worrying.

Therefore, as described above, the present invention is more effective than a normal pneumatic method by pressure-feeding water-resistant bubbles that have been previously foamed with a foaming liquid and air in a foaming device to the face part of the front face of the cutter of the shield machine. The pressure is created to stabilize the face, and the above-mentioned air bubbles resistant to water are pumped into the chamber by another system to reduce the rotation resistance of the cutter in the chamber, and the bubble mixed soil is introduced into the chamber and the screw. By making the face more stable by filling it with water, giving the excavated soil non-permeability and non-permeability, and eliminating the possibility of secondary construction pollution even if the excavated soil is discarded. It is intended to provide a shield excavation method which is advantageous from the above.

(Examples) Examples of the present invention will be described below with reference to the drawings. 1 and 2, 1 is ground, 1a is a shaft, 2 (Fig. 1) is a shield machine, 2 '(Fig. 2) is a shield shield machine for propulsion, 3 is cotton wool, 4 is a facet. Chamber facing 5
Is a screw earth unloader, 6 (Fig. 1) is a segment, 7
(Fig. 2) is a propulsion pipe. Reference numeral 8 in the drawing denotes a propulsion jack, which is interposed between the shield machine 2 and the front end face of the segment 6 in the case of FIG. 1, and in the rear part of the propulsion shield machine 2'in the case of FIG. Propulsion tube 7 connected and arranged with
Is arranged so as to propel the rear end of the vertical shaft 1a. Further, 9 is an earth discharging conveyor established by being connected to the screw type earth discharging machine 5.

10 is a foaming device, which is provided in the shaft 1a in the case of FIG.
In the case of FIG. 2, it is installed on the ground 1. The foaming device 10 can be installed in the tunnel pit 11 depending on the space. Bubbles are sent from the foaming device 10 through a foaming pipe 12. The foam sending pipe 12 is branched into a face injection pipe 13 and an in-chamber injection pipe 14, and flow rate control valves 15 and 15 'are respectively inserted therein. A face bubble pressure detector 16 is attached to the foam feeding pipe 12. Further, a cutter pressure detector 17 and a screw discharge pressure detector 18 are attached to the shield machine 2 and the propulsion shield machine 2 '. Reference numeral 19 in the figure is a displacement detector of the propulsion jack 8.

FIG. 3 shows a control system diagram of the foaming device 10 in the microcomputer 20 in which the amount of bubbles, the opening degree of the gate 5a of the screw type earth discharging machine 5 and the screw 5b (first
(See FIG. 2 and FIG. 2). Reference numeral 21 is a block having a statistical processing function of each data entered in the microcomputer 20, 22 is a signal amplifier of the face bubble pressure P by the bubble pressure detector 16, and 23 is a tank of bubble liquid.

FIG. 4 is a circuit block diagram showing an example of the foaming mechanism of the foaming device 10, 20 is the microcomputer, 24
Is a signal that converts each signal from analog to digital
A / D converter, 25 is a D / A for converting a digital signal output from the microcomputer 20 into an analog signal
The converters 26 and 26 'are electronic shutoff shift control panels for bubble liquid and air, and 27 and 27' are periodic rotation proportional control motors for bubble liquid and air, respectively. Also, 2
Reference numerals 8 and 28 ′ are bubble liquid and air clutch brakes, respectively, which are brake devices for limiting the upper and lower limits of the face bubble pressure P. Reference numeral 29 is a variable pump, and a check valve 31 is inserted in the liquid feeding pipe 30. 32 is a compressor, and the air from this compressor 32 is the air pipe 3
3 is sent to the foam tube 34, where it is mixed with the bubble liquid to form air bubbles, and the bubbles are sent to the downhole by the bubble pipe 12 as described above.

In the method of the present invention, by using the above-mentioned device, air bubbles are separately fed to each of the front face and the chamber of the shield machine, the face bubble pressure at the time of shield excavation, the cutter pressure, the screw soil discharge. The detected values of pressure and digging speed are sent to the microcomputer 20, and they are statistically analyzed, and the amount of bubbles injected into the front face of the cutter and the amount of bubbles injected into the chamber are controlled based on the analysis results. To do. And at the same time, the screw 5 of the screw excavator 5
The rotation speed of b and the opening degree of the gate 5a are also controlled to keep the bubble pressure of the face constant, and the rotation resistance of the cutter is set to an appropriate level to create an optimum excavation state.

As the foaming liquid to be used in the tank 23, a surfactant added with a superabsorbent polymer or a protein-based foaming agent is suitable. For example, polyoxyethylene alkylphenol ether sodium sulfate. Escort L (trade name) containing as a main component, a super absorbent polymer, for example, Sumika gel (trade name) containing a vinyl alcohol acrylate copolymer as a main component, or
Examples include those to which aqua keep (trade name) containing sodium polyacrylate as a main component is added, and escort K (trade name) containing partially hydrolyzed protein as a main component.

Next, an example of the method of the present invention using the apparatus configured as described above will be described. According to the method of the present invention, at the time of excavation, the variable pump 29 is driven to send the foaming liquid in the tank 23 to the foaming pipe 34, and at the same time, the air is sent to the foaming pipe 34 via the air supply pipe 33 by the compressor 32 to foam and foam. The produced air bubbles are fed into the shield machine 2, the face 3 of the cutter front face of the shield machine 2 ′ for propulsion, and the chamber 4 by the foam pipe 12. By doing so, a compressed air state that is more effective than the normal compressed air method is created, and the face 3 can be stabilized. In addition, the rotation resistance of the cutter in the chamber 4 can be reduced, and the bubble mixed soil is filled in the chamber 4 and the screw excavator 5.
Further stabilize the face 3. Then, the top of the excavation can be made impermeable. Also, if the mixed air and sand is left in the dumping place, the air bubbles will naturally disappear and it will be the same as normal excavated sand and sand, so there is no risk of pollution problems.

Further, in the method of the present invention, each data of face bubble pressure, cutter pressure, screw discharge pressure and excavation speed during shield excavation is instantly collected in the microcomputer 20, and statistically analyzed, and the analysis result Based on the above, the amount of bubbles pressed into the face 3 of the cutter and the amount of bubbles pressed into the chamber 4 are controlled, and the rotation speed of the screw 5b of the screw excavator 5 and the opening of the gate 5a are also controlled. The bubble pressure can be kept constant, and the rotational resistance of the cutter can be adjusted to an appropriate level to control so as to create an optimum excavation state.

That is, the face air bubble pressure detector 16, the cutter pressure detector 17, and the screw discharge pressure detector 18 detect the respective pressures, and the displacement by the propulsion jack 8 is detected by the displacement detector 19, and these output signals are A / A / D with D converter 24
The data is converted and sent to the microcomputer 20, the data is statistically analyzed, and the optimum control signal is sent to the electronic unauthorized conversion controller 26, 26 'through the microcomputer 20 based on the analysis result. Is used to change the number of revolutions of the periodic rotation proportional control radars 27 and 27 'to control the discharge amount of the variable pump 29. At the same time, by controlling the amount of air from the compressor 32, the amount of bubbles generated from the foam tube 34 and the mixing ratio of the amount of bubble liquid and the amount of air can be changed and adjusted to an optimum value.

The bubbles sent from the foaming pipe 34 through the foaming pipe 12 are diverted into the face injection pipe 13 and the injection pipe 14 into the chamber 4, and the bubbles are generated by controlling the flow control valves 15 and 15 ′ with the microcomputer 20. It is possible to control the rotational resistance of the cutter by adjusting the amount, keeping the bubble pressure of the face constant. Of course, in order to make these adjustments precise, the rotation speed of the screw 5b and the opening of the gate 5a of the screw excavator 5 can be controlled to create an optimum excavation state.

(Effect of the invention) Since the method of the present invention is as described above, according to this method, a compressed air state that is more effective than the normal compressed air method is created, the face is stabilized, and the rotation resistance of the cutter in the chamber is increased. By improving the excavation performance and filling the mixed soil in the chamber and the screw, it is possible to obtain an effect that the face can be further stabilized. In addition, since the excavated soil can be made impermeable and it is not necessary to treat the excavated soil as industrial waste, the method of the present invention has an excellent effect that it is very advantageous in terms of pollution control. .

[Brief description of drawings]

1 and 2 are vertical sectional views showing the excavated state of the ground by the method of the present invention. FIG. 3 is a schematic diagram showing a control system of the foaming device, and FIG. 4 is a schematic diagram showing a structure of the foaming device. 1 ... Ground 1a ... Vertical shaft 2 ... Shield excavator 2 '... Propulsion shield excavator 3 ... Face face 4 ... Chamber 5 ... Screw excavator 6 ... Segment 7 ... Propulsion pipe 8 ... … Propulsion jack 9 …… Soil removal conveyor 10 …… Foaming device 11 …… Tunnel mine 12 …… Bubbling pipe 13 …… Face injection pipe 14 …… Chamber injection pipe 15 …… Mud volume control valve (cut face side) 15 '... Flow control valve (inside chamber) 16 ... Face bubble pressure detector 17 ... Cutter pressure detector 18 ... Screw discharge pressure detector 19 ... Displacement detector 20 ... Microcomputer 21 ... Data Block having processing function 22 ... Amplifier 23 ... Bubbling liquid tank 24 ... A / D converter 25 ... D / A converter 26 ... Electronic cutoff shift controller (for bubbling liquid) 26 ...... Electronic cut-off shift controller (for air) 27 ...... Periodic rotation proportional control motor (for air bubble liquid) 27 '...... Periodic rotation proportional control motor (for air) 28 ...... Clutch brake (air bubble liquid side) 28' ...... Clutch brake (air side) 29 …… Variable pump 30 …… Liquid supply pipe 31 …… Check valve 32 …… Compressor 33 …… Air supply pipe 34 …… Bubbling pipe 35 …… Bubbling pipe.

Claims (1)

[Claims] 1. A bubble is preliminarily foamed with a foaming liquid and air to the front face of a shield machine, the bubble pressure is applied to the face to maintain the stability of the face, and the bubble is also provided in the chamber by another system. A shield excavation method characterized in that the mixed soil is filled in the chamber and the soil discharge screw by pumping and mixing with the excavated soil.