JP7774385B2 - Foreign object protection device and foreign object protection method - Google Patents

Description

This invention relates to technology related to expandable gaskets installed inside the departure and arrival tunnel entrances of shield machines. More specifically, it relates to a foreign object protection device that prevents foreign objects that would hinder the expansion of the expandable gasket from moving to the expandable gasket, and a foreign object protection method using the device.

The shield tunneling method involves digging underground with a shield machine while stabilizing the tunnel face, and then lining the tunnel with segments to build underground railway tunnels, road tunnels, water and sewerage tunnels, utility conduits, and tunnels for power and communications.

Tunnels constructed using the shield method (hereafter simply referred to as "shield tunnels") are planned to be located deeper than the ground surface, so a departure shaft is typically formed at the start of the shield tunnel to lower the shield machine to the excavation depth, while a destination shaft is typically formed at the end of the shield tunnel to pull the shield machine up to the ground.

When excavating a shield tunnel, it is naturally necessary to install a shield machine at the excavation depth within the departure shaft (hereinafter referred to as the "departure shaft portal"). Typically, the shield machine is suspended in sections from the ground and assembled at the departure shaft portal. Once assembled, the shield machine begins to excavate from the departure shaft portal into the natural ground, and as this excavation progresses, groundwater and soil begin to flow into the departure shaft portal. If groundwater and soil are allowed to flow into the departure shaft portal, there is a risk of the departure shaft becoming submerged, resulting in personal injury to workers, and there is also a risk of the natural ground collapsing, causing significant damage to the surrounding environment.

For this reason, as shown in Figure 6, gaskets are sometimes installed at the departure tunnel entrance. The gasket is attached to the inner circumference of a ring-shaped tunnel entrance hardware installed at the departure tunnel entrance, and this gasket closes the gap between the outer circumference of the shield machine (i.e., the skin plate) and the tunnel entrance hardware, preventing groundwater and sediment from flowing into the departure tunnel entrance. However, the rotating part of the shield machine's cutter can sometimes interfere with this gasket when passing through it, so in these cases, expandable gaskets are preferred.

Figure 7 is a step diagram showing a schematic example of the operation of the expandable gasket, and is an enlarged cross-sectional view of "Part A" shown in Figure 6. As shown in Figure 7(a), the expandable gasket is initially positioned along the wellhead hardware, leaving a specified gap between the skin plate and the wellhead hardware. This allows the shield machine to advance toward the natural ground without the cutter rotating part interfering with the expandable gasket. Once the cutter rotating part has passed, the expandable gasket expands as shown in Figure 7(b), closing the gap between the skin plate and the wellhead hardware. This prevents groundwater and soil generated during the shield machine's excavation from flowing into the starting tunnelhead.

When the rotating part of the cutter passes the expansion packing, some excavation will occur, which means that a certain amount of excavated soil may flow into the departure shaft. In this case, gravel and other materials may have accumulated at the departure shaft, particularly around the expansion packing. If the expansion packing expands in this state, the gap between the skin plate and the shaft opening hardware will not be sufficiently closed, as shown in Figure 8. When gravel is trapped between the skin plate and the expansion packing in this way, groundwater will be allowed to flow in, and there is a risk that the departure shaft will be submerged, so this must be avoided for the safety of workers.

Technologies have been proposed to address the issue of groundwater inflow into the departure shaft. For example, Patent Document 1 proposes a technology that prevents groundwater from inflowing by using wire brush packing attached to a ring-shaped steel plate in a cylindrical shaft.

Utility Model Registration No. 3190336

The technology disclosed in Patent Document 1 aims to prevent groundwater from entering a cylindrical shaft, and to solve this problem, a wire brush packing (or packing sealing tube) is configured to contact the outer periphery of the tunneling machine in a three-dimensional manner. Naturally, the wire brush packing and packing sealing tube are designed to be watertight.

However, it is generally difficult to achieve watertightness using wire brushes alone. Patent Document 1 therefore states, "The wire brush packing 200 is filled with grease material 21 (paragraph [0019])." However, filling the wire brush packing 200 with grease material 21 to achieve watertightness requires a considerable amount of grease material 21 and the installation of a filling device, resulting in considerable cost and effort. Furthermore, if watertightness were to be achieved using wire brushes alone, it would require the use of special wire brushes, such as a structure in which the wire brushes are covered with a bag-like material or a structure in which the wires are arranged quite densely, which would also increase procurement costs. Furthermore, because the wire brushes contact the outer periphery of the tunneling machine in a three-dimensional manner, they would need to be installed around the entire circumference of the tunneling machine, which also requires considerable cost and effort for watertightness.

The objective of the present invention is to solve the problems inherent in conventional technology, namely to provide a foreign object protection device and a foreign object protection method using the same that can suppress the obstruction of expansion of an expansion packing caused by foreign objects (such as gravel) during excavation, at a lower cost than conventional technology such as that shown in Patent Document 1.

The present invention is based on an unprecedented concept: it prevents the inflow of sand and gravel for a short period of time until the expansion packing expands, thereby utilizing a shield that allows groundwater to flow through but does not allow sand and gravel to pass through.

The foreign object protection device of the present invention is equipped with a shield to protect the expandable packing installed at the departure tunnel entrance (or arrival tunnel entrance) from foreign objects generated during excavation by the shield machine. This shield has the function of allowing water to pass through but not foreign objects. The foreign object protection device of the present invention is installed at the departure tunnel entrance (or arrival tunnel entrance) on the natural ground side of the expandable packing and so as to correspond to part (or all) of the outer periphery of the skin plate of the shield machine. In this way, the shield located between the cutter rotating part of the shield machine and the expandable packing can prevent the passage of foreign objects that would interfere with the expansion action of the expandable packing.

The foreign object protection device of the present invention can also use a brush-like shield formed from multiple wires.

The foreign object protection method of the present invention uses the foreign object protection device of the present invention to protect an expandable packing installed at the departure tunnel entrance (or arrival tunnel entrance) from foreign objects generated during excavation by a shield machine. The method comprises a foreign object protection device installation process and an excavation process. In the foreign object protection device installation process, the foreign object protection device of the present invention is installed at the departure tunnel entrance (or arrival tunnel entrance) on the natural ground side of the expandable packing and so as to correspond to part (or all) of the outer periphery of the skin plate of the shield machine. In the excavation process, the shield machine excavates from the departure tunnel entrance toward the natural ground (or from the natural ground to the arrival tunnel entrance).

The foreign object protection device and method of the present invention have the following effects.
(1) Since the inflow of sand and gravel is prevented at least until the expansion packing expands, the expansion packing's expansion inhibition can be suppressed. As a result, the expansion packing expands sufficiently to close the gap between the skin plate and the tunnel head hardware, preventing groundwater and soil from flowing into the starting tunnel head during shield machine excavation, and preventing the starting shaft from being submerged or the ground from collapsing.
(2) Since it does not allow sand and gravel to pass through but allows groundwater to flow through, there is no need to procure special wire brushes, etc., and therefore it can be implemented at a lower cost than conventional techniques such as those shown in Patent Document 1.

A cross-sectional view schematically showing a situation in which a shield machine starts from a starting tunnel entrance where a foreign object protection device of the present invention is installed. (a) is a cross-sectional view showing a schematic diagram of a foreign object protection device attached to the inner circumference of a ring-shaped wellhead metalwork, (b) is an enlarged front view showing a schematic diagram of a part of the foreign object protection device equipped with a shield, and (b) is an enlarged side view showing a schematic diagram of the shield of the foreign object protection device. A cross-sectional view schematically showing a situation in which the expansion packing has expanded sufficiently to close the gap between the skin plate and the wellhead hardware due to the effect of the foreign object protection device of the present invention. A cross-sectional view schematically showing a situation in which a shield machine enters an access tunnel portal where a foreign object protection device of the present invention is installed. 1 is a flow chart showing the main steps of a foreign object protection method according to the present invention. A cross-sectional view schematically showing the starting tunnel entrance where a packing is installed and the shield machine excavating into the natural ground. 1A is a step diagram schematically showing the state before the expansion type packing is expanded, and FIG. 1B is a step diagram schematically showing the state after the expansion type packing is expanded. FIG. 10 is a cross-sectional view schematically showing a state in which a foreign object is caught between the skin plate and the expansion packing.

Examples of the foreign object protection device and foreign object protection method of the present invention are described below with reference to the accompanying drawings.

1. Overview The present invention protects an expandable gasket from foreign objects (e.g., gravel) that may impede its expansion when a shield machine begins excavation from a starting tunnel portal (i.e., starting) or reaches a destination tunnel portal. More specifically, the object protection device of the present invention, located at the starting tunnel portal (or destination tunnel portal) closer to the natural ground than the expandable gasket, blocks excavated soil (e.g., gravel) generated when the shield machine starts moving, preventing the excavated soil from moving toward the expandable gasket until the expandable gasket begins to expand, thereby enabling normal expansion. The object protection device of the present invention includes a shield that allows groundwater to pass through but prevents excavated soil from passing through. This prevents the inflow of gravel and other debris until the expandable gasket expands, without requiring excessively high performance.

2. Foreign Object Protection Device Next, the foreign object protection device of the present invention will be described in detail. Note that the foreign object protection method of the present invention is a method of protecting an expandable packing from foreign objects using the foreign object protection device of the present invention. Therefore, the foreign object protection device of the present invention will be described first, and then the foreign object protection method of the present invention will be described.

Figure 1 is a cross-sectional view showing a schematic diagram of a shield machine MC starting from a departure tunnel entrance where a foreign object protection device 100 of the present invention is installed. At the departure tunnel entrance (or arrival tunnel entrance) where the foreign object protection device 100 of the present invention is used, an expandable packing 200 is installed on the inner periphery of a ring-shaped tunnel entrance hardware 400. Of course, as shown in this figure, the foreign object protection device 100 of the present invention can also be used at a departure tunnel entrance (or arrival tunnel entrance) where a spare packing 300 is installed in addition to the expandable packing 200.

The foreign object protection device 100 is installed at the departure (or arrival) tunnel entrance, closer to the natural ground than the expandable packing 200. More specifically, as shown in Figure 2(a), it is attached to the inner periphery of the ring-shaped tunnel entrance hardware 400. Note that in this figure, the foreign object protection device 100 is attached to correspond to the entire outer periphery of the skin plate of the shield machine MC, i.e., around the entire circumference of the tunnel entrance hardware 400. However, this is not limited to this, and the foreign object protection device 100 may also be attached to correspond to only a portion of the outer periphery of the skin plate, i.e., to a portion of the tunnel entrance hardware 400 (at one or more locations).

The foreign object protection device 100 also includes a shield 110, as shown in Figures 2(b) and 2(c). Figure 2(b) is an enlarged front view of a portion of the foreign object protection device 100 including the shield 110, and Figure 2(c) is an enlarged side view of the shield 110 of the foreign object protection device 100. As previously mentioned, this shield 110 has the function of preventing (shielding) excavated soil such as gravel generated during excavation by the shield machine MC (hereinafter referred to as "foreign objects" for convenience) from passing through, while allowing fluids such as groundwater (liquids, gases, etc.) to pass through. For example, Figure 2 shows the shield 110 as a brush-like object (such as a wire brush) formed from multiple wires. Alternatively, a mesh-like object (such as wire mesh) or a scrubbing brush-like object (such as a metal scrubbing brush) can also be used as the shield 110. However, it is desirable to use a material that is elastic enough to easily deform in response to the movement of the shield machine MC, and also has considerable strength.

As shown in Figure 1, the foreign object protection device 100 should be installed so that the shield 110 is approximately perpendicular (including perpendicular) to the axial direction of the shield machine MC. In prior art, such as Patent Document 1, when wire brushes or other devices are installed at the starting tunnel entrance, they are installed at an angle (i.e., lying down). For example, in Patent Document 1, as shown in Figure 10, the tip of the wire brush packing is installed with a gentle tilt toward the front (the direction of travel of the shield machine MC). This is because the wire brush packing in Patent Document 1 is designed not to interfere with the travel of the shield machine MC, and is also intended to provide watertightness and adhesion. In contrast, the foreign object protection device 100 (particularly the shield 110) of the present invention is designed to prevent the passage of foreign objects and allows the flow of groundwater and other debris, so watertightness and adhesion are not required. Therefore, there is no need to install the shield 110 at a gentle tilt (i.e., lying down), nor is it necessary to place it in close contact with the shield machine MC (skin plate). In other words, the shield 110 can be positioned so that it is approximately perpendicular to the axial direction of the shield machine MC, and can also be installed with a specified gap (smaller than the size of the anticipated foreign object) between the tip of the shield 110 and the skin plate. Installing the shield 110 so that it is approximately perpendicular to the axial direction of the shield machine MC in this way not only prevents flowing foreign objects from passing through, but can also be expected to have the effect of sweeping away any adhering (sticky) foreign objects with the very tip of the brush.

In Figure 1, as the shield machine MC advances toward the natural ground, the expansion packing 200 is positioned along the wellhead hardware 400 (i.e., folded) so as not to interfere with the cutter rotating part CT, and a specified gap is created between the skin plate of the shield machine MC and the wellhead hardware 400. Meanwhile, the cutter rotating part CT has already advanced into the natural ground, meaning that a certain amount of foreign matter has flowed into the starting wellhead. However, since the shield 110 has the function of allowing groundwater and the like to pass through but not foreign matter, the shield 110 restricts the foreign matter from moving further (to the left in the figure), thereby preventing the foreign matter from reaching the position of the expansion packing 200.

In this way, the shield 110 of the foreign object protection device 100 blocks foreign objects generated during excavation, preventing gravel from becoming trapped between the skin plate and the expansion packing 200 (Figure 8). As shown in Figure 3, the expansion packing 200 can expand sufficiently to close the gap between the skin plate and the wellhead hardware 400. As a result, the inflow of groundwater and soil into the starting tunnel entrance during excavation by the shield machine MC can be suppressed, preventing the starting shaft from being submerged and the ground from collapsing.

While the above explanation focuses on an example in which the shield machine MC departs from the departure tunnel portal, the foreign object protection device 100 of the present invention can also be used when the shield machine MC reaches the destination tunnel portal. In Figure 4, when the shield machine MC enters the destination tunnel portal from the natural ground, the expansion packing 200 is folded to prevent interference with the cutter rotating part CT, creating a predetermined gap between the skin plate of the shield machine MC and the tunnel portal hardware 400. Meanwhile, the shield machine MC proceeds through the destination tunnel portal with a portion of it (on the left side in the figure) remaining in the natural ground, meaning that a certain amount of foreign object has been drawn into the destination tunnel portal. However, because the shield 110 allows groundwater and other impurities to pass through but not foreign objects, the shield 110 restricts further movement of the foreign object (to the right in the figure), preventing it from reaching the position of the expansion packing 200. This allows the expansion packing 200 to expand sufficiently to close the gap between the skin plate and the tunnel portal hardware 400.

3. Foreign Object Protection Method Next, the foreign object protection method of the present invention will be described. The foreign object protection method of the present invention is a method for protecting an expandable packing from foreign objects using the foreign object protection device 100 described up to this point. Therefore, we will avoid overlapping explanations with those described for the foreign object protection device 100 and will only describe details unique to the foreign object protection method of the present invention. In other words, details not described here are the same as those described in "2. Foreign Object Protection Device."

As previously mentioned, the foreign object protection device 100 of the present invention can be used when the shield machine MC departs from the departure tunnel entrance, and can also be used when the shield machine MC reaches the destination tunnel entrance. Similarly, the foreign object protection method of the present invention can be implemented when the shield machine MC departs from the departure tunnel entrance, and when the shield machine MC reaches the destination tunnel entrance. For convenience, the following description will use an example in which the shield machine MC departs from the departure tunnel entrance.

Figure 5 is a flow chart showing the main steps of the foreign object protection method of the present invention. As shown in this figure, first, a starting shaft is formed (Step 10 in Figure 5), and then a wellhead hardware 400 is installed at the starting shaft entrance (Step 20 in Figure 5). Next, the foreign object protection device 100 of the present invention is attached to the inner periphery of the wellhead hardware 400 (Step 30 in Figure 5). At this time, the foreign object protection device 100 can be attached so as to correspond to the entire outer periphery of the skin plate of the shield machine MC (i.e., around the entire circumference of the wellhead hardware 400), or it can be attached so as to correspond to only a portion of the outer periphery of the skin plate (i.e., to a portion of the wellhead hardware 400). In addition, an expandable gasket 200 and a spare gasket 300 are also installed at predetermined positions on the inner periphery of the wellhead hardware 400 (Step 40 in Figure 5). However, at this point, the expandable packing 200 and spare packing 300 are positioned along the wellhead hardware 400 (i.e., folded).

The separated shield machine MC is lowered from the ground into the departure shaft, and the shield machine MC is assembled at the departure shaft entrance (Step 50 in Figure 5). Once assembly is complete, the shield machine MC is moved toward the natural ground (Step 60 in Figure 5). Furthermore, as the cutter rotating part CT passes through the expandable gasket 200 and spare gasket 300, these expandable gaskets 200 and spare gaskets 300 are expanded (Step 70 in Figure 5). As shown in Figure 1, as the shield machine MC moves, the cutter rotating part CT enters the natural ground, and a certain amount of foreign matter flows into the departure shaft entrance. However, because the shield 110 has the function of allowing groundwater and the like to pass through but not foreign matter, the shield 110 restricts further movement of the foreign matter. This prevents sand and gravel from becoming trapped between the skin plate and the expansion packing 200 (Figure 8), and allows the expansion packing 200 to expand sufficiently to close the gap between the skin plate and the wellhead hardware 400, as shown in Figure 3.

Once the gap between the skin plate and the wellhead metal fitting 400 is closed, full-scale excavation using the shield machine MC is carried out while maintaining this state (Step 80 in Figure 5).

The foreign object protection device and foreign object protection method of the present invention can be used in the construction of underground road tunnels, as well as railway tunnels, water and sewer tunnels, utility conduits, and tunnels for power and communications. They can also be used for excavation using small- to large-diameter shield machines, or for slurry shield tunneling and earth pressure shield tunneling, and can be used with a wide range of soil types. Given that the present invention enables the safe construction of social infrastructure such as tunnel structures, it is an invention that can be expected to not only be used industrially but also make a significant contribution to society.

100 Foreign object protection device of the present invention 110 Shield (of foreign object protection device) 200 Expandable packing 300 Spare packing 400 Wellhead hardware CT Cutter rotating part MC Shield machine

Claims (2)

A foreign object protection device that protects an expandable packing installed at a starting tunnel entrance or an arrival tunnel entrance from foreign objects generated by excavation by a shield machine,
a shield that allows water to pass through but does not allow the foreign matter to pass through;
It is installed at the departure tunnel entrance or the arrival tunnel entrance on the natural ground side of the expandable packing so as to correspond to part or all of the outer periphery of the skin plate of the shield machine,
the shielding body is installed in an orientation perpendicular or substantially perpendicular to the axial direction of the shield machine , with a predetermined gap being generated between the tip of the shielding body and the skin plate ,
The shielding body located between the cutter rotating part of the shield machine and the expandable packing prevents the passage of the foreign matter that hinders the expansion action of the expandable packing.
A foreign object protection device characterized by: A method for protecting an expandable packing installed at a starting tunnel entrance or a destination tunnel entrance from foreign objects generated during excavation by a shield machine using a foreign object protection device,
a foreign object protection device installation process for installing the foreign object protection device at the departure tunnel entrance or the arrival tunnel entrance on the natural ground side of the expandable packing so as to correspond to a part or all of the outer periphery of the skin plate of the shield machine;
An excavation process in which excavation is performed by the shield machine from the starting tunnel entrance toward the natural ground or from the natural ground toward the arrival tunnel entrance,
The foreign object protection device has a shield that allows water to pass through but does not allow the foreign object to pass through;
the shielding body is installed in an orientation perpendicular or substantially perpendicular to the axial direction of the shield machine , with a predetermined gap being generated between the tip of the shielding body and the skin plate ,
In the excavation step, the shielding body located between the cutter rotating part of the shield machine and the expandable packing prevents the passage of the foreign matter that hinders the expansion action of the expandable packing.
A method for protecting against foreign objects.