JPH08284584A - Method and equipment for controlling internal pressure of expansion-contraction type entrance packing in starting shaft - Google Patents

Abstract

PURPOSE: To conduct proper sealing by controlling the internal pressure of an expansion-contraction type entrance packing in response to groundwater pressure (external pressure). CONSTITUTION: In the control method of the internal pressure of an entrance packing 13 using an expansion-contraction type seal in a starting shaft 1, the groundwater pressure PB of a starting pit mouth 2 in the starting shaft 1 is measured. The internal pressure PA of the entrance packing 13 is controlled in response to the groundwater pressure PB of the starting pit mouth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion-type entrance packing in a starting shaft, and more particularly to an expansion-type entrance packing in a starting shaft for the purpose of performing proper sealing by controlling the internal pressure of the expansion-type entrance packing. Regarding packing.

[0002]

2. Description of the Related Art As a first conventional technique, FIGS.
The configuration of "Jitsuko 56-6550" shown in FIG. At the periphery of the shield starting hole 53 opened in the pit wall 52 of the vertical shaft 51 to start the shield 55, the base end portion is provided with the cylindrical body 5.
A pair of elastic band-shaped rings 58 and 59, which are fixed to 7a and whose opposite ends are wrapped, are provided in the elastic band-shaped rings 58 and 59. A pressing body 61 made of is provided in an annular shape, and by the pressing body 61, the elastic band-shaped rings 5 are formed.
A shield starting vertical wall for sealing a gap formed between the shield starting hole 53 and the shield 55 or the segment 54 by pressing the outer peripheral surfaces of the shield 55 or the segment 54 starting from the shield starting hole 53 with 8, 9 and 59. Sealing device is described. The flexible member 6 is penetrated through the segment 60 and the flexible member 61.
A fluid injection hole 62 for supplying a fluid to the space 61a formed by 1 is provided.

The operation of the first conventional technique will be described.
When the shield 55 is started from the vertical shaft 51, first, when an elastic body is used for each elastic belt ring and the pressing body 61 in 59, the tip of the shield 55 is sufficiently shrunk to expand the diameter, and the tip of the shield 55 is shielded from the starting hole 53. After being inserted into the inside, the contraction of the pressing body 61 is released, and when the pressing body 61 is an expansion and contraction bag, the pressing body 61 is inserted from the fluid injection hole 62 installed through the segment 60 and the pressing body 61. A fluid is supplied to the formed void 61a. As a result, the tip ends of the elastic band-shaped rings 58 and 59 are pressed against the outer peripheral surface of the shield 55 by the restoring force of the elastic body or the expansion of the expansion / contraction bag, and the gap formed between the shield starting hole 53 and the shield 55 is sealed. Further, when the shield 55 passes through the shield starting hole 53, the segment 54 following the shield 55
Reaches the seal body 56. The outer diameter of the segment 54 is smaller than that of the shield 55, but the pressing body 61 further expands as the shield 55 passes and presses the tip ends of the elastic strip rings 58 and 59. 58 and 59 reach the outer peripheral surface of the segment 54 as shown by the chain double-dashed line in FIG.
3 and the segment 54 will be sealed.

As a second conventional technique, the structure of "Actual Kaihei 5-22697" shown in FIG. 8 will be described. A tubular tail shield 70 is provided at the rear of the tunnel excavator, and an expansion / contraction seal 7 is provided near the rear of the inner peripheral surface of the tail shield 70.
In the tail seal device of the tunnel excavator to which 2 is attached, the tail seal device of the tunnel excavator in which the soft rubber 71 is continuously attached to the outer surface of the rubber 74 forming the expansion-contraction seal 72 in the circumferential direction is described. Has been done. A fluid supply hole 79 is provided in the tail shield 70, and the fluid is supplied from the fluid supply hole 79 to the void 80 formed of the rubber 74.

The operation of the second conventional technique will be described.
By supplying the fluid from the fluid supply hole 79 to the void 80 constituted by the rubber 74, the rubber 74 of the expansion / contraction seal 72 is
Is extended, the soft rubber 71 attached to the outer surface of the rubber 74 is pressure-bonded to the segment 73 to form gaps 75, 76 caused by the axial step A and the circumferential step B of the segment 73.
The soft rubber 71 is closed to improve the waterproofness.

[0006]

However, in the first prior art and the second prior art, since the sealing surface pressure is a set constant pressure, it becomes impossible to endure and leak water when the groundwater pressure becomes high. However, if it is set to withstand an unnecessarily high groundwater pressure, there is a problem in durability of the seal, and there is a problem in that cost is increased to solve this problem. In addition, when the shield machine enters during excavation, there is a possibility that the seal surface pressure will suddenly rise due to a sharp increase in the tightening allowance from the state where there is no tightening allowance, and that the seal machine will pass and the segment will pass. There is a problem in that, when the space between and is sealed, the tightening margin is sharply reduced and the seal surface pressure is rapidly reduced, so that the change cannot be followed and water leakage occurs.

[0007]

In order to achieve the above object, the method for controlling the internal pressure of the expansion / contraction entrance packing in the starting shaft according to the present invention comprises the steps of measuring the groundwater pressure PB at the opening of the starting shaft in the starting shaft. It consists of controlling the internal pressure PA of the entrance packing according to the groundwater pressure PB at the starting pit entrance.

The method for controlling the internal pressure of the expandable / retractable entrance packing is to measure the internal pressure PA of the entrance packing and the groundwater pressure PB of the starting hole, and PA-PB = P
The step of calculating α and the step of controlling the internal pressure PA of the entrance packing so that this Pα becomes a predetermined value also include the step of measuring the groundwater pressure PB at the starting pit entrance,
It may also include a step of calculating PA = PB + Pα (predetermined value) and a step of controlling the internal pressure of the expansion / contraction entrance packing to be PA. Further, the internal pressure control method of the expansion type expansion packing is as follows: measuring the internal pressure PA of the entrance packing, comparing the internal pressure PA of the entrance packing with a set pressure P0, and the internal pressure PA.
And the step of calculating the differential pressure between the set pressure P0 and this differential pressure (P
It is possible to control the internal pressure PA of the entrance packing to be the set pressure P0 according to A-P0), and it is also possible to switch the method to the internal pressure control method of the other expansion-contraction type entrance packing.

An internal pressure control device for an expansion / contraction type entrance packing according to the present invention is an internal pressure control device for an entrance packing using an expansion / contraction type seal in a starting shaft.
The control valve for the inner pressure PA of the entrance packing, the means for detecting the groundwater pressure PB at the starting pit entrance, and the groundwater pressure PB signal are input, and the control signal for the inner pressure PA of the entrance packing is calculated according to this groundwater pressure PB signal. Calculated internal pressure P
The controller outputs a control signal of A to the control valve.

In the internal pressure control device of the entrance packing using the expansion-contraction seal, a control valve for the internal pressure PA of the entrance packing and an internal pressure P of the entrance packing are provided.
A and each pressure detecting means for detecting the groundwater pressure PB at the starting pit entrance, and the internal pressure PA signal and the groundwater pressure PB signal are input to calculate the differential pressure signal (PA-PB) = Pα, and the calculated difference The pressure Pα signal is the internal pressure PA of the entrance packing.
The control valve for controlling the internal pressure PA of the entrance packing, the pressure detecting means for detecting the groundwater pressure PB at the starting point, and the groundwater pressure P
Input the B signal to calculate the inner pressure PA = (PB + Pα) of the entrance packing, which is higher than the groundwater pressure PB signal by the predetermined pressure Pα, and output the calculated inner pressure PA of the entrance packing to the control valve of the inner pressure PA of the entrance packing. It can also consist of a controller.

Further, in an internal pressure control device for an entrance packing using an expansion / contraction type seal, a control valve for the internal pressure PA of the entrance packing, a pressure detecting means for detecting the internal pressure PA of the entrance packing, and an internal pressure PA signal for this entrance packing are provided. A comparator for the set pressure P0 signal and a control signal for changing the internal pressure PA of the entrance packing to the set pressure P0 according to the differential pressure (PA-P0) signal are output to the control valve of the internal pressure PA of the entrance packing. The controller may include a controller, which may be provided with switching means for switching to an internal pressure control device of the entrance packing using the other expansion-contraction type seal.

[0012]

When the above-mentioned structure is adopted, the following operation is performed. In the internal pressure control method for the expansion / contraction type entrance packing, the groundwater pressure PB at the starting pit entrance is measured, and the internal pressure PA for the entrance packing is controlled according to the groundwater pressure PB.

In the internal pressure control method for the expandable / retractable entrance packing, the internal pressure PA of the entrance packing and
The groundwater pressure PB at the start pit entrance is measured and P
After calculating A-PB = Pα, the internal pressure PA of the entrance packing is controlled so that this Pα becomes a predetermined value,
The groundwater pressure PB at the start pit entrance was measured, and PA was calculated from this measured value.
After calculating = PB + Pα (predetermined value), the internal pressure of the expansion / contraction entrance packing is controlled to become PA. Further, in the internal pressure control method for the expansion type expansion packing, the internal pressure PA of the entrance packing was measured and compared with the internal pressure PA of the entrance packing and the set pressure P0 to calculate the differential pressure between the internal pressure PA and the set pressure P0. Thereafter, the internal pressure PA of the entrance packing is controlled so as to become the set pressure P0 according to this differential pressure (PA-P0). The internal pressure control method for the expandable / retractable entrance packing can be switched to the internal pressure control method for the other expandable / retractable entrance packing.

In the internal pressure control device for the expansion / contraction type packing according to the present invention, in the internal pressure control device for the entrance packing using the expansion / contraction type seal, the controller inputs the groundwater pressure PB signal detected by the groundwater pressure PB detection means, The control signal of the internal pressure PA of the entrance packing is calculated according to this groundwater pressure PB signal, and the internal pressure PA control valve of the entrance packing is controlled by the calculated control signal of the internal pressure PA.

In the internal pressure control device for the entrance packing using the expansion / contraction type seal, the controller has an internal pressure PA of the entrance packing and a groundwater pressure PB of the starting pit.
By inputting the internal pressure PA signal and the groundwater pressure PB signal detected by the respective pressure detecting means, the differential pressure signal (PA-PB) =
By calculating Pα and controlling the control valve of the internal pressure PA of the entrance packing by the calculated differential pressure Pα signal, the controller also controls the predetermined pressure Pα from the groundwater pressure PB signal detected by the pressure detecting means of the groundwater pressure PB at the starting pit. A high inner pressure PA of the entrance packing PA = (PB + Pα) is calculated, and the control valve of the inner pressure PA of the entrance packing is controlled by the calculated inner pressure PA signal of the entrance packing.

Further, in the internal pressure control device for the entrance packing using the expansion / contraction seal, the controller uses a comparator to compare the internal pressure PA signal of the entrance packing detected by the pressure detecting means for the internal pressure PA of the entrance packing and the set pressure P0 signal. In comparison, the control valve for controlling the internal pressure PA of the entrance packing is controlled by a control signal such that the internal pressure PA of the entrance packing becomes the set pressure P0 according to the differential pressure (PA-P0) signal. Further, the internal pressure control device of this entrance packing can be switched to the internal pressure control device of the other entrance packing. Further, a backup plate is provided in parallel along the outer surface of the entrance packing opposite to the groundwater pressure. This backup plate can be elastically deformed according to the internal pressure of the entrance packing.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an internal pressure control method for a expandable / retractable entrance packing and a control device therefor according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a side sectional view showing an embodiment of an expansion / contraction type entrance packing in a starting shaft according to the present invention, and FIG.
FIG. 3 is an enlarged view of the P portion of FIG. 3, FIG. 3 is a view from the direction of the arrow V of FIG. 1 excluding the excavator A, FIG. 4 is a view showing details of the inside of the controller in FIG. 2, and FIG. FIG. 3 is a diagram showing a flowchart of an internal pressure control system for the expansion / contraction entrance packing in FIG.

In FIG. 1, the ground 9 on the side of the starting shaft 2 is improved. On the inner wall of the excavated starting shaft 1 which is next excavated, a starting shaft opening 2 and a bearing wall 3 for obtaining the tunneling reaction force of the tunnel are installed in the tunnel excavation direction. Is installed. Further, in the starting shaft 1, a shield machine A composed of a front body A1 and a rear body A2 is provided with a shield jack 5 to generate a propulsive reaction force from a segment 6 wound between a temporary support structure 4 and Get and promote. Next, a mirror cut of the mirror portion grounded to the starting hole 2 is performed by fusing. Further, the front surface of the shield machine A projects into the entrance portion 8 of the starting pit 2 and the expansion / contraction entrance packing described in detail in FIG. After that, the excavation of the natural ground 9 is started. The segment 6 is wound up by a segment erector 10, and the rolled up segment 6 is corrected to a perfect circle by a perfect circle holding device 11. FIG. 1 shows a state where mirror cutting is completed by the cutter 7, and shows a state in which the skin plate of the shield machine A is in contact with the expansion / contraction entrance packing portion to seal the entry of groundwater.

In FIG. 2, which is an enlarged view of the P section of FIG. 1, a starting hole 2 is installed on the inner wall of the excavated starting shaft 1 in the excavating direction of the shield machine A. An expansion / contraction type entrance packing 13 is fixed to a pit entrance inner peripheral wall portion 12 installed in the starting pit opening 2 with a fixing bolt 14, and a backup plate 15 is in contact with an outer surface of the expansion / contraction type entrance packing 13. Further, a water supply pipe 16 for supplying muddy water or water into the entrance packing 13 and an external pressure detection pipe 17 for guiding the groundwater pressure outside the entrance packing 13 are installed at the starting pit entrance 2. In this way, the internal pressure PA of the entrance packing 13 is detected by the internal pressure detector 18, and the external pressure (groundwater pressure) PB of the entrance packing 13 is detected by the external pressure detector 19 as an electric signal.

The internal pressures PA and PB detected by the internal pressure detector 18 and the external pressure detector 19 are output to the controller 20, and a predetermined control signal is calculated by the controller 20 as shown in detail in FIG. It is output to the solenoid 22a or 22b of the internal pressure control valve 21. Therefore, the muddy water or water discharged from the pump 23 is controlled by the internal pressure control valve 21 and is supplied into the entrance packing 13.
The two-dot chain line L1 is the maximum diameter portion of the rear body A1, the two-dot chain line L2 is the skin plate portion of the front body A2, and L3 is the segment outer diameter portion. In FIG. 3, the entrance packing 13 is fixed to the starting hole 2 by a stop bolt 14 via a backup plate 15. The two-dot chain line L4 represents the state when the entrance packing is expanded.

The controller 2 in FIG. 2 shown in FIG.
Each embodiment according to the present invention will be described in detail with reference to No. 0. First, a first embodiment of the present invention will be described. The inner pressure detector 18 and the outer pressure detector 19 measure the inner pressure PA of the entrance packing 13 and the outer pressure PB of the entrance packing 13. When the internal pressure signal PA and the external pressure signal PB are input to the controller 20, the arithmetic unit 20a calculates PA-PB as Pα. Next, arithmetic unit 2
0b, P2 and the set value P0 stored in the memory 24a are calculated as i2 = k2 (P [alpha] -P [alpha] 0), and i2 is calculated.
The signal is output to the switching device 25. If i2 <0,
The i2 signal is output from the switching device 25 to the solenoid 22a to move the internal pressure control valve 21 in the direction of the a position, and the pump 2
The muddy water of No. 3 or water is supplied into the entrance packing 13, and PA, that is, Pα is increased to control Pα = Pα0. If i2 ≥0, the i2 signal is output from the switching device 25 to the solenoid 22b to move the internal pressure control valve 21 in the direction of the b position to discharge muddy water or water from the inside of the entrance packing 13 to obtain PA, that is, Pα.
Is reduced to approach Pα = Pα0.

Next, a second embodiment of the present invention will be described. When the external pressure detector 19 measures the external pressure PB of the entrance packing 13 and the controller 20 inputs the external pressure signal PB, the calculator 20c outputs the external pressure signal PB.
B and the set value Pα stored in the memory 24b to PB
+ Pα is calculated as PA, and this P is calculated by the computing unit 20d.
I1 = k1 * PA is calculated from A, and the i1 signal is output to the switching device 25. The i1 signal is output from the switching device 25 to the solenoid 22a to move the internal pressure control valve 21 in the direction of position a to supply muddy water or water from the pump 23 into the entrance packing 13, and the inner pressure of the entrance packing 13 is PA = PB. It is controlled to be + Pα.

Next, a third embodiment of the present invention will be described. When the internal pressure PA of the entrance packing 13 is measured by the internal pressure detector 18 and output to the controller 20, this internal pressure PA and the set value P stored in the memory 24c are measured.
The difference (PA-P0) from 0 is calculated by the calculator 20e as Pβ. In the calculator 20f, the Pβ signal and the memory 2
From the set value Pβ0 stored in 4d, i3 = k3 (Pβ
-Pβ0) is calculated and the i3 signal is output to the switching device 25. If i3 <0, the i3 signal is output from the switching device 25 to the solenoid 22a to move the internal pressure control valve 21 in the direction of the a position to supply muddy water or water of the pump 23 into the entrance packing 13 to set Pβ. The PA is controlled by increasing it so as to approach Pβ0. If i3 ≧ 0, i3
A signal is output from the switching device 25 to the solenoid 22b to move the internal pressure control valve 21 in the b position direction to discharge muddy water from the inside of the entrance packing 13 to change Pβ to Pβ0.
To control PA by decreasing it toward Therefore, PA is controlled so that Pβ is decreased to approach Pβ = Pβ0. Coefficient k in the arithmetic units 20b, 20d, 20f
1 to k3 are solenoids 22a and 22b of the same control valve 21
Have values to adjust for input to. When the solenoids 22a and 22b are not excited at the same time, the centering spring 26 brings the control valve 21 to the c position.

In FIG. 5, when the flow of the internal pressure control system for the expansion / contraction entrance packing is started, the starting hole entrance external pressure PB is measured in step S1. Step S
At 2, measure the initial pressure P0 and the upper limit pressure P1 of the entrance packing. In step S3, the internal pressure PA of the entrance packing is measured. Initial pressure P0 in step S4
Is compared with the internal pressure PA, and if PA ≥P0 is not satisfied, the internal pressure P is applied to the control valve of the expansion type entrance packing in step S5.
An increase signal of A is output and the process returns to step S3. The inner pressure PA of the entrance packing is measured again in step S3, and the initial pressure P0 and the inner pressure PA are compared in step S4. When PA ≧ P0, the inner pressure PA of the entrance packing is the groundwater pressure PB, which is the groundwater pressure. The pressure will ensure a reliable seal. Next, in step S6, the internal pressure PA and the upper limit pressure P1 are compared, and if PA <P1 is not satisfied, step S6
Internal pressure PA to the control valve of the expansion / contraction entrance packing at 3
The decrease signal is output and the process returns to step S3.

If PA ≧ P0 in step S4 and PA <P1 in step S6 again, the internal pressure PA of the entrance packing becomes an appropriate pressure, so that the shield machine A plunges into the entrance portion in step S8. At the same time as this rush, in step S9, the internal pressure PA of the entrance packing
Is measured, and the starting shaft outside pressure PB is measured in step S10. In step S11, the internal pressure PA and the starting pit outside pressure PB
If PA ≧ kPB (k = 1.0 to 1.2) is not satisfied, an increase signal of the internal pressure PA is output to the control valve of the expansion / contraction entrance packing in step S12, and step S9 is performed.
Return to After the inner pressure PA is measured again in step S9 and the starting well entrance outside pressure PB is measured in step S10, and when PA ≧ kPB in step S11, the entrance packing inner pressure PA is surely the starting well entrance outside pressure PB which is groundwater pressure. The pressure is such that it can be sealed. Next, in step S13, the internal pressure PA is compared with the upper limit pressure P1. If PA <P1 is not satisfied, a decrease signal of the internal pressure PA is output to the control valve of the expansion / contraction entrance packing in step S14, and the process returns to step S9. The starting pressure outside the outlet PB is measured again in step S10, PA ≧ kPB in step S11, and step S11.
If PA <P1 at 13, the internal pressure PA of the entrance packing becomes a proper pressure, so the shield machine A is advanced at step S15. If the construction is not completed in step S16, the process returns to step S9. If the construction is completed again in step S16, the flow is completed by lining the entrance portion in step S17.

[0026]

As described above, the following effects can be obtained by the internal pressure control method and the control device for the expansion / contraction entrance packing in the starting shaft according to the present invention. (1) Since the seal contact surface pressure corresponding to the external pressure can be automatically secured against a sudden change in the external pressure, control is simple. Furthermore, it can handle high water pressure and is suitable for excavation in deep underground. (2) By introducing muddy water or water around the starting port as it is, control management for external pressure becomes easy. (3) It is possible to flexibly follow the outer peripheral projection of the shield machine or the segment outer diameter clearance that occurs when passing through the starting opening. (4) The backup plate prevents the entrance packing from being pushed out by the external pressure toward the starting shaft and becoming incapable of sealing. (5) When the internal pressure of the entrance packing is not applied,
Backup plate prevents drooping.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of an expansion / contraction type entrance packing in a starting shaft according to the present invention.

FIG. 2 is an enlarged view of a P part in FIG.

3 is a view as seen from an arrow V in FIG. 1 excluding the excavator A, (A) is an overall view, and (B) is a detailed view of a Q portion of (A).

FIG. 4 is a diagram showing details inside the controller in FIG. 2;

FIG. 5 is a view showing a flowchart of an internal pressure control system for the expansion / contraction type entrance packing in the starting shaft according to the present invention.

FIG. 6 is a diagram showing a first conventional technique.

7 is an enlarged view of a Q portion of FIG.

FIG. 8 is a diagram showing a second conventional technique.

[Explanation of symbols]

1 Start vertical shaft 2 Start shaft 3 Support wall 4 Temporary support 5 Shield jack 6 Segment 7 Cutter 8 Entrance part 9 Ground 10 Segment erector 11 True circle holding device 12 Hole inner peripheral wall 13 Entrance packing 14 Stop bolt 15 Backup plate 16 Water Supply Pipeline 17 External Pressure Detection Pipeline 18 Internal Pressure Detector 19 External Pressure Detector 20 Controller 20a, 20b, 20c, 20d, 20e, 20f Computer 21 Internal Pressure Control Valve 22a, 22b Solenoid 23 Pump 24a, 24b, 24c, 24d Memory 25 Switching device 26 Centering spring A Shield machine PA Internal pressure PB External pressure

Claims (11)

[Claims] 1. A method for controlling an inner pressure of an entrance packing using an expansion / contraction type seal in a starting shaft, wherein a step of measuring a groundwater pressure PB at a starting port of the starting shaft and an entrance according to the groundwater pressure PB at the opening of the starting shaft. A method for controlling the internal pressure of a expandable / retractable entrance packing in a starting shaft, comprising the step of controlling the internal pressure PA of the packing. 2. The method for controlling the internal pressure of a expandable / retractable entrance packing in a starting shaft according to claim 1, wherein the internal pressure PA of the entrance packing and the groundwater pressure PB at the starting hole of the starting shaft in the starting shaft are measured; PB = Pα
And a step of controlling the internal pressure PA of the entrance packing so that this Pα becomes a predetermined value, a method of controlling the internal pressure of the expansion-type entrance packing in the starting shaft. 3. The method for controlling the internal pressure of the expansion-type entrance packing in the starting shaft according to claim 1, wherein the groundwater pressure PB at the starting port of the starting shaft in the starting shaft is measured;
A method for controlling the internal pressure of an expandable entrance packing in a starting shaft, comprising the steps of calculating A = PB + Pα (predetermined value) and controlling the internal pressure of the expandable entrance packing to become PA. 4. A method of controlling an inner pressure PA of an entrance packing using an expansion-contraction type seal in a start shaft, a step of measuring an inner pressure PA of the entrance packing, a step of comparing the inner pressure PA of the entrance packing with a set pressure P0, and an inner pressure. Calculating the differential pressure between PA and the set pressure P0,
An internal pressure control method for an expandable / retractable entrance packing in a starting shaft, wherein the internal pressure PA of the entrance packing is controlled to become a set pressure P0 according to the differential pressure (PA-P0). 5. An internal pressure control method for the expansion-type entrance packing in the starting shaft according to any one of claims 1 to 3 and an internal pressure control method for the expansion-type entrance packing in the starting shaft according to claim 4 can be switched. A method for controlling the internal pressure of an expansion-contraction type entrance packing in a starting shaft. 6. An internal pressure control device for an entrance packing using an expansion / contraction type seal in a starting shaft, a control valve for an internal pressure PA of the entrance packing, a means for detecting a groundwater pressure PB at a starting hole in the starting shaft, and a groundwater pressure. A controller for inputting a PB signal, calculating a control signal for the internal pressure PA of the entrance packing in accordance with the groundwater pressure PB signal, and outputting the calculated control signal for the internal pressure PA to the control valve. Internal pressure control device for expansion / contraction type entrance packing in starting shaft. 7. The internal pressure control device for an entrance packing using the expansion-contraction type seal in the starting shaft according to claim 6, wherein a control valve for the internal pressure PA of the entrance packing, the internal pressure PA of the entrance packing, and the starting in the starting shaft. Each pressure detecting means for detecting the groundwater pressure PB at the wellhead and these internal pressure PA signal and groundwater pressure PB signal are input to calculate a differential pressure signal (PA-PB) = Pα, and the calculated differential pressure Pα signal is calculated. An internal pressure control device for an expansion-contraction type entrance packing in a starting shaft, comprising a controller for outputting a control valve for the internal pressure PA of the entrance packing. 8. The internal pressure control device for an entrance packing using the expansion-contraction type seal in the starting shaft according to claim 6, wherein the control valve for the internal pressure PA of the entrance packing and the groundwater pressure PB at the starting hole in the starting shaft are detected. By inputting this groundwater pressure PB signal, the internal pressure PA of the entrance packing, which is higher than the groundwater pressure PB signal by a predetermined pressure Pα = (PB + Pα), is calculated, and the calculated internal pressure PA signal of the entrance packing is used as the entrance. An internal pressure control device for an expansion-contraction type entrance packing in a starting shaft, comprising a controller that outputs the internal pressure PA of the packing to a control valve. 9. An internal pressure control device for an entrance packing using an expansion-contraction type seal in a start shaft, a control valve for the internal pressure PA of the entrance packing, a pressure detection means for detecting the internal pressure PA of the entrance packing, and a pressure detection means for the entrance packing. A comparator for comparing the internal pressure PA signal and the set pressure P0 signal and a control signal for controlling the internal pressure PA of the entrance packing so that the internal pressure PA of the entrance packing becomes the set pressure P0 according to the differential pressure (PA-P0) signal. An internal pressure control device for expansion-contraction type entrance packing in a starting shaft, comprising a controller for outputting to a valve. 10. A switching means for switching between the internal pressure control device for the expansion-type entrance packing in the starting shaft according to claim 6 and the internal pressure control device for the expansion-type entrance packing in the starting shaft according to claim 9. An internal pressure control device for expansion-contraction type entrance packing in a starting shaft. 11. The internal pressure control device for an expansion-contraction type entrance packing in the starting shaft according to claim 10,
An internal pressure control device for expansion-contraction type entrance packing in a starting shaft, comprising a backup boot.