JPH07301089A - Launching method of shield machine - Google Patents

Abstract

PURPOSE:To prevent the flow out of underground water, sand and earth into a launching shaft surely and very easily, without prolonging a construction period and increasing the cost, and launch a shield machine to a satisfactory manner. CONSTITUTION:Before the front end 4a of a shield machine 4 passes through an improved soil area 3 and arrives at an unimproved soil area, a bag-attached ring 22 is installed in a launching shaft 2 where the end of the bag-attached ring 22 and an opening of a launching entrance are closed with an entrance packing 7 while a back-filling material is filled up in a shielding bag 21 installed the outer peripheral part of the bag-attached ring 22, thereby expanding the bag so as to join with the internal surface of the launching entrance and forming a ring-shaped space on the outer peripheral side of the bag-attached ring 22. Then, excavation work is started again by driving the shield machine 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a shield excavator for excavating a sewer tunnel, an automobile tunnel, a railway tunnel, etc.

[0002]

2. Description of the Related Art As is well known, in the shield construction method, a cutter device provided at a front end portion of a shield excavator having an outer cylindrical skin plate is rotated to excavate the natural ground while the skin plate is being excavated. This is a method of excavating and constructing a tunnel in the ground by connecting rings formed by assembling segments that are cylindrical divided bodies, and further taking a reaction force at the front end of the rings to extend the propulsion jack inside the shield excavator. In the above shield construction method, when the shield excavator is started, as shown in FIG. 7, the ground is formed near the start shaft 2 formed on the side of the start shaft 1 constructed by concrete, for example, by freezing or chemical solution injection. The ground improvement portion 3 formed by hardening was formed, and in this state, the excavation by the shield excavator 4 was started from the starting hole 2 and the temporary ring 5 and the permanent ring 6 were connected.

By the way, the start of the shield excavator 4 is the most troublesome construction stage in the entire construction, and when the shield excavator 4 is started under high water pressure, which is expected to increase in the future, the start pit 2 is opened. Safe and economical measures against the acting water pressure are needed. For this reason,
Conventionally, before the front end portion 4a of the shield excavator 4 reaches the unimproved portion of the ground, the opening portion of the tail void T on the shaft 1 side is closed by an entrance packing 7 made of an iron plate and rubber, and then the tail void T The backfill material 9 was filled in the inside by the backfill injection pump 8.

[0004]

However, in the starting method described above, the backfill material 9 filled in the tail void T flows downward due to gravity, so that the backfill material 9 is sufficiently above the tail void. Therefore, the sealing by the backing material 9 becomes insufficient. That is, when the excavation of the shield excavator 4 is started in this state, when the front end portion 4a of the shield excavator 4 reaches the unimproved portion and groundwater, sand, earth and sand, etc., flow into the tail void T, High pressure acts on the entrance packing 7 on the upper side where the sealing by the backing material 9 is weak, and further, from the weak sealing part of the entrance packing 7 to groundwater,
There is a risk that sand, earth and sand, etc. will flow into the starting shaft 1 and interrupt the excavation work, or that ground subsidence may occur at the upper part of the excavation site.

Therefore, as shown in FIG. 8, the starting shaft 1
In this state, an entrance room 11 is constructed by extending the start pit entrance 2 in the axial direction, and with the shield excavator 4 installed in the entrance room 11, the ring 6 and the shield excavator 4 are separated from the entrance room 11. There is a method of coping with the water pressure by filling the backfill material 9 with the backfill material 9 and even in this method, when the excavation of the shield excavator 4 is restarted, A void is created between the filler material 9 and groundwater, sand, or earth and sand flows into the void, and high pressure acts on the entrance packing 7, causing groundwater, sand, or earth and the like to flow into the starting shaft 1. In addition, the backing material 9 causes the shield excavator 4 to
May adhere to the entrance room 11 and the shield excavator 4 may be unable to restart. Further, in the case of this method, it takes a lot of time and labor to construct the entrance room 11 in the starting shaft 1 and leads to an increase in cost. Furthermore, the construction of the entrance room 11 prolongs the construction period. There was a problem of being lost. Further, in order to construct the entrance room 11, it is necessary to construct a large-diameter starting shaft 1, which further complicates the construction work and prolongs the construction period. Since it can be applied only to a place where the starting shaft 1 can be constructed, it is not a preferable starting method at the present time when the density of buildings is increasing.

The present invention has been made in view of the above circumstances, and does not lead to a longer construction period, higher costs, etc.
It is an object of the present invention to provide a method for starting a shield excavator that can very easily and reliably prevent outflow of groundwater, sand, earth and sand, etc. into the starting shaft.

[0007]

In order to achieve the above-mentioned object, a method for starting a shield excavator according to claim 1 is such that a shield excavator is used to form an excavation hole from a start hole formed laterally in a shaft. A method of starting a shield excavator for starting excavation, in which the ground improvement portion obtained by hardening the ground in the vicinity of the starting hole is excavated by the shield excavator,
Before the shield excavator passes through the ground improvement section,
A ring is installed in the starting hole and the space between the ring and the starting hole is closed at the front side in the excavation direction and the rear side in the excavation direction to form an annular space part, and a filler is filled in the space part. It is characterized by filling and curing.

A starting method of the shield excavator according to a second aspect is the starting method of the shield excavator according to the first aspect, wherein the end of the ring on the rear side in the excavating direction and the opening of the starting wellhead are formed. While closing with packing,
A shield bag is provided on the outer peripheral side of the ring on the front side in the excavation direction, and the shield bag is filled with a filler to be closely attached to the inner surface of the start hole, thereby closing the space between the ring and the start hole and forming an annular shape. It is characterized by forming a space part of.

[0009]

According to the starting method of the shield excavator according to the first aspect, the ring is installed in the starting hole of the starting hole before the shield excavator passes through the ground improvement section near the starting hole of the starting hole. An annular space is formed by blocking the front side and the rear side in the excavation direction of the space with the starting hole, and the annular space is filled with a filling material and cured to form an annular seal. Parts are formed. After that, the excavation of the shield excavator is restarted, and when the front end of the shield excavator passes through the ground improvement part and reaches the unimproved part of the ground, groundwater, sand, earth and sand, etc. from the unimproved part,
It flows into the tail void of the shield excavator. At this time, since a seal part made of a hardened annular filler is formed between the ring and the starting hole, the outflow of groundwater, sand, earth and sand, etc., flowing into the tail void to the vertical shaft is reliably prevented. It

Further, according to the starting method of the shield excavator of the second aspect, by filling the inside of the shielding bag provided on the outer peripheral side of the ring with the filler, the shielding bag expands and the inner surface of the starting pit mouth is expanded. In close contact with. That is, a packing that closes the end on the rear side in the excavation direction of the ring and the opening of the starting shaft entrance,
The space between the ring and the inner surface of the starting hole is closed by the shielding bag expanded by the filling with the filling material, and an annular space is formed. In this state, the filling material is filled into the annular space portion and cured, so that the space portion filled with the filling material serves as a seal portion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a starting method for a shield excavator according to the present invention will be described below with reference to the drawings. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. First, the ground in the vicinity of the starting pit mouth 2 is set beforehand as the ground improvement section 3 which is hardened by freezing or injecting a chemical solution, and the shield excavator 4 is installed in the starting pit mouth 2 and the temporary side is provided behind the shield excavator 4. A temporary ring 5 consisting of segments is installed. Next, a front end portion 4a is cut by a cutter device (not shown) provided on the front end portion 4a side of the shield excavator 4.
While excavating the ground improvement section 3 on the side, a temporary ring 5 is further connected to the rear side of the shield excavator 4 (see FIG. 1).

Further, when the excavation by the shield excavator 4 is advanced and the tail 4b of the shield excavator 4 passes through the opening of the starting wellhead 2, a steel segment is formed inside the starting wellhead 2 and an annular shape is formed on the outer peripheral side thereof. The bag-equipped ring 22 provided with the shielding bag 21 is installed, and the bag-equipped ring 22 and the opening of the starting hole 2 are closed by the entrance packing 7. With the front end 4a of the shield excavator 4 inside the ground improvement section 3, when the tail 4b of the shield excavator 4 exceeds a predetermined size (about 300 mm) from the bag ring 22, the excavation by the shield excavator 4 is stopped, and the bag is closed. A back-filling material such as instant-setting air mortar is injected into the shielding bag 21 of the attached ring 22 by the back-filling injection pump 8 to inflate the shielding bag 21, and its outer peripheral side is the inner circumference of the starting hole 2 Stick it to the side. In this way, the ring with bag 2
An annular space K defined by the bag ring 22, the starting hole 2, the shielding bag 21, and the entras packing 7 is formed on the outer peripheral side of 2 (see FIG. 2).

Then, from the grout hole (not shown) formed in the bag ring 22, a backfilling pump 8 is used to fill the space K with a backfilling material 9 such as instant-setting air mortar, The backing material 9 is cured. By doing so, the seal portion S formed by filling the backing material 9 in the annular space portion K is formed (see FIG. 3). In this state, the excavation by the shield excavator 4 is restarted, the adjustment ring 23 is connected to the bag ring 22 to adjust the axial length, and then the permanent ring 6 made of a concrete segment is connected. While continuing the excavation. Then, the back void material 9 is injected into the tail void T on the outer peripheral side of the main ring 6 by the back void injection pump 8 (see FIG. 4). Furthermore, while continuing to excavate the shield excavator 4,
A tunnel is constructed while connecting the main rings 6 and filling the tail voids T on the outer peripheral side of the main rings 6 with the backing material 9 (see FIG. 5).

Here, the front end portion 4a of the shield excavator 4
However, when the ground improvement part 3 reaches the unmodified part, that is, the soft ground, groundwater, sand, earth and sand flow into the tail void T from the soft ground, and the inflowing groundwater, sand, earth and sand, etc. Backing material 9 filled in the tail void T
From a portion where the backfill material 9 is insufficiently filled on the upper side of the tail void T, toward the opening portion of the starting wellhead 2, but a bag is formed near the opening of the starting wellhead 2. An annular space K defined by the attached ring 22, the starting hole 2, the shielding bag 21, and the entras packing 7.
An annular seal portion S formed by filling the backing material 9 and hardening it
As a result, the groundwater, sand, earth and sand flowing into the tail void T can be reliably prevented from flowing into the opening of the starting hole 2. As a result, it is possible to reliably prevent the interruption of the excavation work and the occurrence of ground subsidence above the excavation site due to the inflow of groundwater, sand, earth and sand, etc. into the starting shaft 1.

After that, the temporary ring 5 in the starting shaft 1 is removed, and the entrance packing 7 and the bag ring 22 are
A plate (not shown) is completely closed by welding to perform a water-stop treatment, and then a decorative concrete 24 is placed at the water-stop location where the plate is welded and closed (see FIG. 6).

As described above, according to the starting method of the shield excavator of the above-described embodiment, the starting shaft 1 can be carried out without performing a large-scale work such as constructing the entrance room 11.
It is possible to reliably prevent outflow of groundwater, sand, earth and sand, etc. into the interior, eliminate problems due to the outflow of groundwater, sand, earth, sand, etc. into the vertical shaft 1 and start the shield excavator 4 extremely well. be able to.

[0017]

As described above, according to the starting method of the shield excavator of the present invention, the following effects can be obtained. According to the starting method of the shield excavator according to claim 1, before the shield excavator passes through the ground improvement portion near the start hole, the space between the ring installed in the start hole and the start hole is in the front in the excavating direction. And the rear side in the excavation direction is closed to form an annular space, and the annular seal can be formed by filling the interior of the annular space with a filler and curing it. When the machine passes through the ground improvement section and reaches the unimproved section, even if groundwater, sand, earth and sand, etc., flow into the tail void from the unimproved section, the seal section allows the starting pit opening for groundwater, sand, earth and sand, etc. It is possible to reliably prevent the outflow from the opening of the to the vertical shaft. As a result, it is possible to reliably prevent interruption of excavation work due to inflow of groundwater, sand, earth and sand, etc. into the shaft, and occurrence of ground subsidence above the excavation site. That is, as compared with a large-scale method of constructing an entrance room, it is possible to reliably prevent the outflow of groundwater, sand, earth and sand, etc. into the shaft at a low cost without prolonging the construction period, The shield excavator can be launched extremely well.

According to the starting method of the shield excavator according to the second aspect, the end of the ring on the rear side in the excavating direction and the opening of the starting hole are closed by packing, and the shielding bag provided on the outer peripheral side of the ring. By filling the inside with the filling material, it is possible to extremely easily form the annular space portion serving as the seal portion.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a starting hole for explaining an embodiment of a starting method for a shield excavator according to the present invention.

FIG. 2 is a cross-sectional view of a starting hole for explaining an example of a starting method for a shield excavator according to the present invention.

FIG. 3 is a cross-sectional view of a starting hole for explaining an example of a starting method for a shield excavator according to the present invention.

FIG. 4 is a cross-sectional view of a start hole for explaining an embodiment of a start method for a shield excavator according to the present invention.

FIG. 5 is a cross-sectional view of a starting hole for explaining an example of a starting method for a shield excavator according to the present invention.

FIG. 6 is a cross-sectional view of a starting hole for explaining an example of a starting method for a shield excavator according to the present invention.

FIG. 7 is a cross-sectional view of a starting hole for explaining a starting method of a conventional shield excavator.

FIG. 8 is a cross-sectional view of a starting hole for explaining a starting method of a conventional shield excavator.

[Explanation of symbols]

 1 Starting shaft (vertical shaft) 2 Starting shaft entrance 3 Ground improvement part 4 Shield excavator 7 Entrance packing (packing) 9 Backfill material (filling material) 21 Shielding bag 22 Ring with ring (K) Space section

Claims (2)

[Claims] 1. A method of starting a shield excavator, which starts excavation of an excavation hole by a shield excavator from a start hole formed laterally in a shaft, wherein the ground near the start hole is hardened. Excavate the ground improvement section by the shield excavator, before the shield excavator passes through the ground improvement section,
A ring is installed in the starting hole and the space between the ring and the starting hole is closed at the front side in the excavation direction and the rear side in the excavation direction to form an annular space part, and a filler is filled in the space part. A method for starting a shield excavator, which comprises filling and hardening. 2. An end of the ring on the rear side in the excavating direction and an opening of the starting hole are closed by a packing, and a shielding bag is provided on the outer peripheral side of the ring on the front side in the excavating direction. The shield excavator according to claim 1, wherein a space between the ring and the starting hole opening is closed by forming a ring-shaped space portion by filling a filling material and closely contacting the inner surface of the starting hole opening. How to start.