JPH0425399B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an excavation method using a shield excavator,
In particular, the present invention relates to an excavation method using a shield excavator that can prevent the spouting of pore water in the cutter chamber and reliably control the amount of earth removed by calculating the true earth pressure.

[Prior Art] Generally, when tunnel excavation work is carried out using a shield tunneling machine, the cutter chamber is filled with excavated soil and the excavated soil is added as appropriate while maintaining a predetermined pressure to prevent the collapse of the face ground. It needs to be ejected backwards.

That is, excavated soil and pore water usually coexist inside the cutting chamber, and each of these is applied to the cutting chamber as earth pressure and water pressure. In order to prevent the collapse of the face, which can cause ground subsidence, the pressure determined by the slack height, that is, the height from this excavator to the ground, must always be kept the same as the earth pressure in the cutter room. need to be maintained.

However, in the past, an earth pressure water pressure gauge was installed in the bulkhead that partitioned the cutter room to measure the total value of earth pressure and water pressure (this is because earth pressure alone cannot be directly measured independently); The amount of soil discharged has been controlled by changing the rotation speed of the screw conveyor so that the measured value approaches a predetermined control value.

[Problems to be solved by the invention] By the way, in the conventional excavation method, when the cutter chamber is filled with only excavated soil with little moisture, the measured value of the earth pressure water pressure gauge is almost the same as that of soil. There is no problem because only the pressure is displayed, but if there is not only excavated soil but also pore water and the water pressure increases as the excavation machine advances, the measured value of the earth pressure water pressure gauge will become high, causing a problem. arise. In other words, in this case as well, the screw conveyor is rotated to remove soil so that the measured value of the earth pressure water pressure gauge approaches the predetermined control value, but the soil plugs formed inside the screw conveyor while it is stopped are This rotation caused the screw to collapse, and since the water pressure inside the cutter was rising, there was an inconvenience that an eruption occurred through the screw conveyor. In particular, the above-mentioned disadvantages are a major problem in the shield construction method, which employs a construction method in which additives such as clay or bentonite are injected under pressure into the face ground for soil modification.

[Object of the Invention] The present invention focuses on the above-mentioned problems and has been devised to effectively solve the problems.

The purpose of the present invention is to make the water pressure in the cutter chamber slightly higher than the underground water pressure at the face, and to obtain the true earth pressure by calculating the differential pressure between the total pressure of earth pressure and water pressure and the water pressure. To provide an excavation method using a shield excavator, which can control the amount of earth discharged in a cutter chamber to maintain a set earth pressure control value, and thereby reliably prevent spouting of pore water and collapse of the face. It is in.

[Summary of the Invention] The configuration of the present invention that achieves the above object is to measure the water pressure in the cutter chamber to obtain a water pressure measurement value, and compare this measurement value with the face groundwater pressure to find that the water pressure measurement value is slightly higher. While removing the pressure in the cutter chamber, measure the total pressure of the earth pressure and water pressure in the cutter chamber to find the total pressure measurement value, find the differential pressure between this measurement value and the water pressure measurement value above, and calculate this difference. The gist of this invention is to control the amount of soil discharged in the cutter chamber so that the pressure is maintained at a preset earth pressure management value.

[Example] A preferred example of the method of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an example of a shield tunneling machine for carrying out the method of the present invention.

As shown in the figure, 1 is a cylindrical shield frame, and a cutter frame 2 is attached to the tip of the shield frame so as to cover the entire shield frame. A cutter chamber 3 for temporarily storing excavated soil is formed behind the cutter frame 2, and a cylindrical bulkhead 5 that partitions this cutter chamber 3 is fixed to the shield frame 1 side. A partition wall 4 connected to the rear of the cutter frame 2 and partitioning the side of the cutter chamber 3 is rotatably supported on the shield frame 1 side via a thrust bearing 30 and a radial bearing 31, and rotates the cutter frame 2. I'm starting to do that. Further, a bulkhead seal 6 is installed between the partition wall 4 and the outer periphery of the bulkhead 5. As a drive source for the cutter frame 2, a motor 7 is fixedly installed on the shield frame 1 side, and this and the partition wall 4 are connected via a gear mechanism 8. The bulkhead 5 has a screw conveyor 9 whose inlet end 9a is located in the cutter chamber 3 for discharging the excavated soil to the rear.
is installed.

The bulkhead 5 is provided with a water pressure gauge 10 and an earth pressure water pressure gauge 11 facing into the cutter chamber 3. This water pressure gauge 10 is installed inside a pipe 10b that opens into the cutting chamber 3 so as to close it, and a filter 10a crosses the open end of the pipe 10b that opens into the cutting chamber 3. In order for the water pressure gauge 10 to measure only the water pressure of the pore water, the filter 10a is arranged at the open end of the pipe 10b to allow only the pore water to pass through and block the earth pressure containing excavated soil particles. It's summery. Further, a well-known device is used as the earth pressure water pressure gauge 11, so that the total pressure of earth pressure and water pressure can be measured. Normally, it would be required to measure only earth pressure, but since it is difficult or impossible to directly measure only earth pressure, the total pressure of earth pressure and water pressure is measured, and this is combined with water pressure. This is to indirectly determine the contact pressure as the true earth pressure.
Further, the shield frame 1 is provided with a face groundwater pressure gauge 12 having the same structure as the water pressure gauge 10 to measure the water pressure at the face. That is, a water pressure gauge 12 is provided in the pipe 12b that opens underground at the face, and a filter is installed at the open end of the pipe 12b facing the underground face to block earth pressure containing excavated soil particles and allow only groundwater to pass through. 12a is fixed. And the water pressure gauge 10 and the earth pressure water pressure gauge 11
and each measurement value obtained by the face groundwater pressure gauge 12,
The information is transmitted to the control unit 13 via the communication line.

On the other hand, a tank 14 for storing a geological improvement agent produced by mixing clay or bentonite into water as an additive is provided at the rear of the shield excavator in the direction of excavation, and an injection pump 15 is connected to the tank 14 midway.
An injection passage 16 extends to the cutter frame 2 through the injection channel 16, so that the geology of the face can be improved by the injected geological improvement agent.

A pressure relief passage 17 is provided to connect this tank 14 and the inside of the cutting chamber 3, and a pressure relief valve 18 is interposed in the middle of this passage to discharge the interstitial water inside the cutting chamber 3. This pressure is relieved by this method.

On the other hand, the control section 13 has a storage section for storing preset earth pressure management values, etc., in addition to a calculation section that compares and processes various measured values input thereto. The valve opening degree of the pressure relief valve 13 and the rotation speed of the screw motor 19 are controlled based on the calculated values in the control section 13.

That is, the control unit 13 compares the water pressure measurement value with the face groundwater pressure and issues a valve opening control signal to the pressure release valve 18 so that the water pressure measurement value becomes slightly higher. At the same time, the screw motor 1 is operated so that the differential pressure between the total pressure measurement value of earth pressure and water pressure and the water pressure measurement value is determined, and this maintains the preset earth pressure management value.
9, a rotational speed control signal is issued to control the amount of soil discharged.

Next, the method of the present invention will be specifically explained based on the apparatus configured as described above.

First, the water pressure of the pore water in the cutter chamber 3 is measured with the water pressure gauge 10 installed in the bulkhead 5.
The earth pressure water pressure gauge 11 measures the total pressure of earth pressure and water pressure. The obtained water pressure measurement value and total pressure measurement value are each transmitted to the control unit 13.

On the other hand, the ground water pressure gauge 12 provided on the shield frame 1 measures the underground water pressure of the face ground, and this measured value is similarly transmitted to the control unit 13. Here, the geological improvement agent is injected under pressure from the tank 14 toward the front of the face, and because the excavator excavates, the water pressure (measured water pressure value) in the cutter chamber 3 is always higher than the underground water pressure at the face. There is a tendency to If the water pressure in the cutter chamber 3 becomes excessively high, there is a risk that the earth plugs will collapse and erupt when the screw conveyor 9 is started or when the screw is rotating, so it is necessary to prevent this from happening. Therefore, in the method of the present invention, the water pressure measurement value inputted to the control unit 13 and the underground water pressure at the face are subjected to a comparison calculation process, and the pressure relief valve 18 is adjusted so that the water pressure measurement value is slightly higher than the underground water pressure at the face. A valve opening control signal 20 is issued toward the That is, when the water pressure measurement value is too high, the valve is opened or the valve opening is increased to increase the amount of muddy water extracted from the cutter chamber 3 to reduce the water pressure in this chamber, and conversely, the water pressure measurement value is too low. When there is almost no difference between this and the groundwater pressure at the face, the pressure in this chamber is increased by reducing the opening degree of the valve or by closing it completely to reduce or eliminate the amount of muddy water extracted. The ideal differential pressure between the water pressure measurement value and the underground water pressure at the face is set and stored in advance in the control unit 13, and if this differential pressure does not cause an eruption,
In addition, the optimal differential pressure for excavation is normally set. The muddy water extracted from the cutter chamber 3 is transferred to the pressure relief passage 1.
7 into the tank 14, or discharged to the outside of the tunnel through a not-shown drain.

On the other hand, in the control unit 13, active earth pressure or static earth pressure determined by the distance between the excavator and the ground E, that is, the loosening height h, is preset and stored as an earth pressure management value. Then, in the calculation section of the control section 13, the differential pressure between the total pressure measurement value input thereto and the above-mentioned water pressure measurement value is determined. This differential pressure represents the true earth pressure, and the amount of earth removed is controlled so that this differential pressure maintains a preset earth pressure control value. The amount of soil removed is controlled by the screw motor 1.
This is done by issuing a rotation speed control signal 21 to the rotation speed 9 to control the rotation speed. In other words, if the differential pressure (true earth pressure) is greater than the earth pressure control value, the screw conveyor 9 is started to start the soil removal operation, or if it has already been started, its rotation speed is If the differential pressure is smaller than the earth pressure control value, the screw conveyor 9 is stopped and the earth removal operation is stopped, or the screw conveyor 9 is stopped even if it is already at a certain speed. If it is rotating, the number of revolutions is lowered to reduce the amount of soil removed, and in either case, the amount of soil removed is controlled so that the differential pressure always matches the earth pressure control value.

In this way, the true earth pressure in the cutting chamber 3 can always be made to match the earth pressure control value determined by the loosening height, so that no voids are created in the cutting chamber 3 and the face ground is Collapse can be reliably prevented.

In addition, since the water pressure in the cutter chamber 3 is only slightly higher than the underground water pressure at the cutting face due to the pressure release, the earthen plug that was formed inside the cutter chamber 3 during the stoppage collapsed when the screw was rotated to carry out the soil removal operation. No eruption occurs even in the event of an accident.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects can be achieved.

(1) We prevent this water pressure from rising excessively by releasing pressure in the cutter chamber and maintain it at a level slightly higher than the face groundwater pressure at all times. Even if it collapses, no eruption will occur.

(2) The true earth pressure inside the cutter room is determined, and the amount of earth removed is controlled so that this earth pressure maintains the earth pressure control value calculated and set in advance.
No voids are created in the cutter chamber, and collapse of the face ground can be prevented.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a shield tunneling machine for carrying out the method of the present invention. In the figure, 3 is the cutting room, 9 is the screw conveyor, 10 is the water pressure gauge, 11 is the earth pressure water pressure gauge, 12 is the face groundwater pressure gauge, 13 is the control section, 18 is the pressure relief valve, and 20 is the valve opening degree. The control signal 21 is a rotation speed control signal.

Claims (1)

[Claims] 1. In an excavation method using a shield excavator in which the excavated soil is filled into the cutter chamber and discharged backward in the excavation direction, the water pressure in the cutter chamber is measured to obtain a water pressure measurement value, and the water pressure measurement value is combined with the water pressure measurement value. The pressure inside the cutter chamber was relieved so that the measured water pressure value was slightly higher than the underground water pressure at the face, and
Measure the total pressure of earth pressure and water pressure inside the cutter room to obtain a total pressure measurement value, calculate the differential pressure between the total pressure measurement value and the above water pressure measurement value, and manage the earth pressure with this differential pressure set in advance. An excavation method using a shield excavator, characterized in that the amount of earth discharged in the cutter chamber is controlled so as to maintain the value.