Earth retaining pipe for forming an access tunnel and underground pipeline construction method using the same

Abstract

To provide an earth retaining tube for forming a reach shaft and an underground tube construction method, which allows a wide work space in a tube without using a large tubular member and does not impair the water stop properties of water stop rubber.SOLUTION: An earth retaining tube 1 for forming a reach shaft according to the present invention includes a tubular member 2, a plurality of sheets of water stop rubber 3 provided overlappingly on an inner surface of the tubular member 2, a protection sheet 4 provided on an inner surface of the tube in the innermost water stop rubber of the tubular member 2, a water stop rubber support member 5 when supporting the water stop rubber 3 and the protection sheet 4, and a soil cutting member 10 provided at a tip of the tubular member 2. A tube insertion hole 9 into which a propulsion tube enters is formed in the water stop rubber 3.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to a method for constructing underground pipelines for laying buried pipes horizontally in the ground. [Background technology]

[0002] When laying underground pipes such as water and sewer pipes and gas pipes horizontally underground, if there are no obstacles above ground, it is possible to lay the pipes by digging a trench above ground. However, if there is already a waterway or fence above the section where the buried pipe is to be laid, digging a trench above ground requires removing those obstacles and then rebuilding them after the buried pipe laying work is completed, which increases the amount of work, costs, and time required. Furthermore, if water is flowing in the waterway, it may not be possible to stop the waterway.

[0003] One construction method involves installing a propulsion machine inside a pre-built vertical shaft (starting shaft) and propelling the pipe horizontally from the starting shaft to construct an underground pipeline. This allows for the creation of a horizontal underground pipeline without touching waterways or walls above ground. However, in order to connect the other end of this horizontally laid buried pipe to another pipe, a vertical shaft (arrival shaft) must be excavated at the other end and the connection work must be carried out inside the arrival shaft. This requires watertight measures to prevent groundwater and soil from seeping into the space where these work is carried out. Therefore, a chemical injection technique is used in which a hardening agent is injected in advance around the arrival shaft (Patent Document 1).

[0004] In the invention of Patent Document 2, an earth-retaining guide pipe having a cylindrical guide pipe body, a horizontal hole provided in the side wall near the tip of the guide pipe body, and an elastic sheet provided on the outside of the guide pipe body so as to cover the horizontal hole is inserted vertically into the ground to form an arrival tunnel, and a propulsion pipe is propelled horizontally from the starting tunnel and inserted into the horizontal hole while the tip of the propulsion pipe is pressed against the elastic sheet of the earth-retaining guide pipe, a water-stopping section is formed between the propulsion pipe and the horizontal hole by the elastic sheet, and a hole is made in the elastic sheet with the tip of the propulsion pipe to connect the earth-retaining guide pipe and the propulsion pipe.

[0005] In the invention of Patent Document 3, the retaining pipe for forming an access tunnel has a tubular member, a watertight rubber, a watertight rubber support member provided inside the tubular member, and a soil cutting member provided at the tip of the tubular member, and a pipe insertion hole is formed in the watertight rubber. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-207783 [Patent Document 2] Japanese Patent Publication No. 2005-282315 [Patent Document 3] JP 2014-37733 A Summary of the Invention [Problem to be solved by the invention]

[0007] When laying buried pipes that run horizontally underground, it is effective to drive the jacking pipe horizontally from the starting tunnel to avoid obstacles such as waterways above the pipes, but this requires taking water-stopping measures to prevent groundwater and soil from entering the work space. However, ground improvement using chemical injection as described in Patent Document 1 is a supplementary and temporary construction method, and in ground containing a large amount of permeable groundwater or in construction locations where there is a concern about water leakage from waterways, chemical injection alone does not provide a sufficient water-stopping effect.

[0008] The earth-retaining guide pipe and underground pipeline construction method of Patent Document 2 enable the construction of underground pipelines while preventing groundwater and soil from entering the work space, without requiring workers to enter the arrival tunnel. An elastic sheet covering the horizontal tunnel prevents groundwater and soil from entering the arrival tunnel before it is connected to the jacking pipe. The elastic sheet also forms a watertight seal when the jacking pipe is inserted into the earth-retaining guide pipe, preventing groundwater and soil from entering the arrival tunnel or the jacking pipe during construction. However, the earth-retaining guide pipe of Patent Document 2 has a rubber sheet attached to the outside of the guide pipe body, and its protruding portion creates resistance when inserted into the ground. This makes insertion particularly difficult in hard ground. Furthermore, although the rubber sheet does not have any holes and is designed to be drilled with the tip of the jacking pipe, it has proven difficult to actually drill through the highly elastic rubber sheet.

[0009] The earth retaining pipe for forming an access tunnel in Patent Document 3 has a pipe insertion hole formed in the waterstop rubber, eliminating the need to drill the waterstop rubber with the jacking pipe. This allows for easy watertightness while connecting the jacking pipe. The waterstop rubber is attached so that the tip of the jacking pipe does not come into contact with the waterstop rubber until the hole in the hole cover plate is completely drilled. Once the hole in the hole cover plate is completely drilled, the rotation of the jacking pipe is stopped and the jacking pipe is inserted, preventing damage to the waterstop rubber. However, the jacking pipe must penetrate deeply into the tubular member. Therefore, when the jacking pipe is fully inserted, the distance from the tip of the jacking pipe to the inner wall at the back of the tubular member becomes short. When a horizontal buried pipe is inserted into the jacking pipe and connected to a vertical buried pipe introduced from above the access tunnel, the space available for this connection is limited. To achieve sufficient space, a larger-diameter tubular member would be required, which increases the cost of materials and installation. Furthermore, if the construction site is not large enough, a large tubular member cannot be used.

[0010] Furthermore, when the thrust pipe enters the hole in the watertight rubber, the tip of the thrust pipe may damage the watertight rubber, thereby impairing its watertightness.

[0011] The object of this invention is to provide an earth retaining pipe for forming an access tunnel and an underground pipeline construction method that allows for a large working space inside the pipe without using large tubular members and does not impair the water-stopping properties of the water-stop rubber. [Means for solving the problem]

[0012] To solve the above problems, the present invention provides an earth-retaining pipe for forming an access tunnel, comprising a tubular member, multiple waterstop rubbers stacked on the inner surface of the tubular member, a protective sheet attached to the inner surface of the innermost waterstop rubber of the tubular member, a waterstop rubber support member supporting the waterstop rubbers and the protective sheet, and a soil-cutting member attached to the tip of the tubular member, the waterstop rubber having a pipe insertion hole. The waterstop rubbers include an outer waterstop rubber that contacts the inner surface of the tubular member and an inner waterstop rubber that is located inside the outer waterstop rubber, and the inner waterstop rubber is preferably thicker than the outer waterstop rubber. The tubular member preferably has a cylindrical main body, a hole formed in the side of the main body, and a hole cover member attached to the outer surface of the main body to cover the hole, the waterstop rubber being attached to the inner surface of the hole cover member.

[0013] Furthermore, the underground pipeline construction method of this invention is an underground pipeline construction method that uses the above-mentioned retaining pipe for forming the arrival tunnel, in which the retaining pipe for forming the arrival tunnel is rotated and driven vertically into the ground to form the arrival tunnel, and a sheath pipe having a soil cutting member at its tip and an outer diameter larger than the inner diameter of the pipe insertion hole in the watertight rubber is rotated and sent from the starting tunnel side toward the arrival tunnel, and while rotating the sheath pipe, it is brought into contact with the retaining pipe for forming the arrival tunnel and the hole cover member is cut with the tip of the sheath pipe, and the sheath pipe is inserted into the pipe insertion hole in the watertight rubber and a watertight section is formed with the watertight rubber while the sheath pipe is connected to the retaining pipe for forming the arrival tunnel, and the main pipe is sent from the starting tunnel side to the arrival tunnel through the sheath pipe to form an underground pipeline from the starting tunnel side to the arrival tunnel. [Effects of the Invention]

[0014] The earth retaining pipe for forming an access tunnel of this invention has sufficient space inside the pipe, making it easy to connect horizontal and vertical buried pipes. Even when the sheath pipe, which serves as the jacking pipe, pushes and widens the holes in the watertight rubber as it enters, the watertightness of the watertight rubber is not impaired. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a front view showing a retaining wall pipe for forming an access tunnel. [Figure 2] FIG. [Figure 3] AA cross-sectional view of the same. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. 2 is a development view of a water-stop rubber support member. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. 10 is a development view of another example of a water-stop rubber support member. [Figure 14] This is a conceptual diagram showing the underground pipeline construction method. [Figure 15] 1 is a flowchart showing the steps of the underground pipeline construction method. [Figure 16] FIG. 10 is a cross-sectional view showing the state in which the propulsion pipe has reached the target position. [Figure 17] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a front view of an earth-retaining pipe for forming an arrival tunnel, Fig. 2 is a left side view, Fig. 3 is a cross-sectional view taken along line AA, Fig. 4 is a cross-sectional view taken along line BB, and Fig. 5 is a cross-sectional view taken along line CC. The earth-retaining pipe for forming an arrival tunnel 1 includes a tubular member 2, a water-stop rubber 3, the water-stop rubber 3 provided inside the tubular member 2, a protective sheet 4 that protects the water-stop rubber 3, and a water-stop rubber support member 5.

[0017] The tubular member 2 is a cylindrical member that forms the main body of the earth-retaining pipe for forming an access tunnel of this invention. It can be formed from a cylindrical steel pipe or other material. In this example, a hole 6 is provided in a portion of the side, and a hole cover plate 7 is attached to cover the hole. In this case, the hole cover plate 7 is also included in the tubular member. In this example, a cylindrical pipe 8 with sufficient strength is used as the main body of the tubular member 2, and a steel pipe is used here. When constructing an underground passage, a sufficient inner diameter is required to insert a vertical buried pipe into the tubular member 2 and connect it to a horizontal buried pipe within the tubular member 2. However, as described below, these operations can be performed without workers entering the access tunnel, allowing the use of a much smaller pipe. Moreover, the present invention provides sufficient working space within the pipe, making it possible to apply pipes less than 500 mm in length, which have not been used previously. For example, it is preferable to select an outer diameter between 400 mm and 800 mm, and a length between 800 mm and 1000 mm. In particular, in this example, a steel pipe (φ400 steel pipe) with an outer diameter of 406.4 mm and a thickness of 6.4 mm is used. A rectangular hole 6 is drilled on the side of this steel pipe at the position where the waterproof rubber 3 will be installed. This hole 6 is oriented in the direction in which the jacking pipe will enter during construction, and the jacking pipe passes through this hole. However, this hole 6 is formed to be larger than the outer diameter of the jacking pipe.

[0018] A hole cover plate 7 is provided on the outside of hole 6 to cover hole 6. Figure 6 is a front view of the hole cover plate, and Figure 7 is a plan view of the same. Hole cover plate 7 is large enough to cover hole 6, and is made by bending a rectangular steel plate so that it has a curved surface that fits the outer surface of cylindrical member 8. It is made of a material that has a certain degree of strength but is weaker than cylindrical member 8. In this case, a steel plate with a thickness of 4.5 mm is used, which is thinner than cylindrical member 8.

[0019] Figure 8 is a development view of the watertight rubber. A rectangular rubber sheet is used for the watertight rubber 3. A pipe insertion hole 9 is formed in the center of the watertight rubber 3. The diameter of this pipe insertion hole 9 is slightly smaller than the diameter of the thrust pipe (sheath pipe) to be inserted. For example, when the outer diameter of the sheath pipe is 250 mm, the diameter of the pipe insertion hole 9 of the watertight rubber 3 is set to about 200 mm.

[0020] The watertight rubber 3 is provided in multiple layers. Here, two layers are layered: an outer watertight rubber 3a that contacts the inner surface of the tubular member 2, and an inner watertight rubber 3b that is provided inside the outer watertight rubber 3a. A lubricant is applied between the outer watertight rubber 3a and the inner watertight rubber 3b to reduce friction between the two watertight rubbers. The inner watertight rubber 3b is thicker than the outer watertight rubber 3a; in this example, the outer watertight rubber 3a is 5 mm thick and the inner watertight rubber 3b is 10 mm thick. By making the inner watertight rubber 3b this thick, sufficient watertightness can be achieved with just the inner watertight rubber 3b. While the inner watertight rubber 3b contributes to the watertightness of the outer watertight rubber 3a, it also functions to protect the inner watertight rubber 3b when the sheath tube enters.

[0021] Figure 9 is a development of the protective sheet. It is rectangular, the same shape as the watertight rubber 3, but has no holes. It is attached to the inside surface of the watertight rubber 3, i.e., the surface facing the inside of the tubular member 2. The protective sheet 4 preferably has moderate elasticity, and a smooth sheet with a low coefficient of friction is used. This reduces resistance from soil and sand when the sheet is driven into the ground while rotating, effectively preventing damage to the watertight rubber. In this example, a sheet made of glass fiber fabric coated with a silicone resin is used. The sheet is 0.3 mm thick and is made of plain-woven glass fiber fabric.

[0022] The waterstop rubber support member 5 is a member for supporting the waterstop rubber 3 and protective sheet 4 inside the tubular member 2. Fig. 10 is a developed view of an example of a waterstop rubber support member, Fig. 11 is a front view of the same, and Fig. 12 is a plan view of the same. In this example, the waterstop rubber support member 5 is a bent, plate-like member formed as a single unit, and is made of a 4.5 mm thick steel plate. In the developed view, it is a rectangle with the same outer periphery as the waterstop rubber 3 and protective sheet 4, but there is a large rectangular cutout inside, giving it the shape of a rectangular frame. The waterstop rubber support member 5 is formed by bending this so that it forms a curved surface that roughly follows the inner surface of the hole cover plate 7.

[0023] The hole cover plate 7, the watertight rubber 3, the protective sheet 4 and the watertight rubber support member 5 are provided with bolt holes 12 aligned with one another along the periphery.

[0024] The hole cover plate 7 is attached by welding to the outer surface of the pipe so as to cover the hole 6 in the cylindrical member 8 (the main body of the tubular member). The waterstop rubber 3 is then attached to the inner surface of this hole cover plate 7. At this time, the pipe insertion hole 9 of the waterstop rubber 3 is filled with lubricant 11. A silicone bond specially designed for bonding to protective sheets is applied to the inner surface of the waterstop rubber 3, and the protective sheet 4 is then placed on top of it. In this way, the protective sheet 4 is firmly attached to the waterstop rubber 3 and integrated into it. The waterstop rubber support member 5 is then placed on the inside of that. Bolts are passed through the bolt holes 12 from the outside of the hole cover plate 7, and nuts are attached and tightened on the inside. This secures the outer periphery of the waterstop rubber 3 and protective sheet 4 to the inner surface of the hole cover plate 7. The head of the nut is then welded to the hole cover plate 7, and the nut head can be ground off with a grinder to reduce protrusion outside the pipe.

[0025] Figure 13 is a development view of another example of a watertight rubber support member. In this figure, the watertight rubber support member 5 is separated into a pair of horizontal strip-shaped plates 5a and a pair of vertical strip-shaped plates 5b. When all of these are assembled, the shape resembles the example in Figure 10. Dividing it into four parts like this makes manufacturing easier. Also, with a one-piece member, all of the bolt holes 12 must be precisely aligned with the bolt holes in the watertight rubber 3 and protective sheet 4, which can be difficult. However, in this example, the four parts can be positioned independently of each other, making alignment easier.

[0026] The above has been explained using an example in which the tubular member 2 is composed of a cylindrical member 8 and a hole cover plate 7. Using a hole cover plate 7 that is thinner than the cylindrical member 8 has the advantage of making it easier to cut with the sheath tube and to insert it into the tubular member 2. The waterstop rubber 3 and protective sheet 4 are arranged so that they fit inside the hole 6 of the cylindrical member 8. Unlike this example, the tubular member 2 can also be formed only from the cylindrical member 8. In this case, the water-stop rubber 3 and the protective sheet 4 are attached to the inner surface of the cylindrical member 8.

[0027] The lower end of the tubular member 2 is provided with multiple high-hardness cutting claws called metal crowns as soil cutting members 10. These soil cutting members 10 enable effective cutting of soil and sand, making it easier to insert the tubular member 2 into the ground.

[0028] Next, we will explain the underground pipeline construction method using retaining pipes for forming arrival tunnels. Figure 14 is a conceptual diagram that shows the underground pipeline construction method, and Figure 15 is a flowchart showing the steps of the underground pipeline construction method. This underground pipeline construction method uses a jacking method that sends out a sheath pipe horizontally from the starting tunnel toward the arrival tunnel. This type of jacking method has already been put into practice and is disclosed in Japanese Patent Application Laid-Open No. 2006-193983 and Japanese Patent Application Laid-Open No. 2006-214086, etc.

[0029] The starting tunnel 20 is formed by a well-known method such as a manhole. A driving machine 21 is installed in the starting tunnel 20 to drive the jacking pipe x laterally into the ground from the starting tunnel 20.

[0030] Meanwhile, a retaining pipe 1 for forming an arrival pit is inserted vertically at the position where the jacking pipe x is to reach, forming a vertical shaft that will serve as the arrival pit. In soil types with high permeability such as sand or gravel that do not stand upright, soil with confined water, ground with strong groundwater flow, or ground where groundwater may rise from below a vertical buried pipe, in addition to using the retaining pipe 1 for forming an arrival pit, auxiliary construction methods such as chemical grouting are also implemented. If there is a water leak, the filler material will be diluted by groundwater and the like when it is poured between the jacking pipe x and the buried pipe 24 (described later), causing problems such as the filler material not being strong enough. However, these problems can be prevented by using auxiliary construction methods such as chemical grouting. The earth-retaining pipe 1 for forming the arrival tunnel is driven in by a shaft-forming propulsion machine 23. The propulsion machine 23 grips the earth-retaining pipe 1 for forming the arrival tunnel and rotates it while inserting it into the ground. Since there are no protrusions on the outer or inner surface of the earth-retaining pipe 1 for forming the arrival tunnel, there is little resistance to rotation. Even so, the soil inside the earth-retaining pipe 1 for forming the arrival tunnel comes into contact with the inner surface of the tubular member 2, but the inner surface of the water-stop rubber 3 is covered with a protective sheet 4, preventing damage from contact with the soil. A soil cutting member 10 is attached to the tip of the earth-retaining pipe 1 for forming the arrival tunnel, so the soil is effectively cut away by its rotation. This allows the earth-retaining pipe 1 for forming the arrival tunnel to be erected even in hard soil.

[0031] Once the arrival tunnel forming earth retaining pipe 1 has been inserted to a certain extent into the ground, a steel pipe of the same diameter is added on top by welding or other means, and the pipe is further erected. The soil inside the steel pipe is then removed by auger removal or vacuum suction. In this way, the arrival tunnel 22 is formed. The pipe insertion hole 9 of the waterproof rubber 3 of the arrival tunnel forming earth retaining pipe 1 is oriented toward the starting tunnel 20. If necessary, a small amount of cement liquid may be poured into the arrival tunnel 22 to harden the bottom and prevent groundwater and soil from flowing in from the bottom.

[0032] Once the arrival tunnel 22 is formed, the jacking pipe x is sent from the starting tunnel 20 toward the pipe insertion hole 9 of the arrival tunnel formation earth retaining pipe 1. The tip of the jacking pipe x is also equipped with multiple high-hardness cutting claws called metal crowns, which are shaped like a sawtooth. This jacking pipe x is rotated and advanced toward the arrival tunnel 22. The soil inside the jacking pipe x is discharged by suction from the starting tunnel 20. When the tip of the jacking pipe x reaches the arrival tunnel formation earth retaining pipe 1, it reaches the side of the tubular member 2 and drills a hole in the side. The saw-shaped tip of the jacking pipe x is pressed against the hole cover plate 7 as it rotates, forming a hole in the hole cover plate 7. Here, because the hole cover plate 7 is also shaped like a cylindrical shell, the tip of the jacking pipe x first comes into contact with the hole cover plate 7 at its top and bottom. Cutting of the hole cover plate 7 begins from this point. When the hole cover plate 7 is cut down to the inner surface at this point, the tip of the jacking pipe x comes into contact with the outer waterproof rubber 3a. However, at this point, drilling of the hole in the hole cover plate 7 is not complete. The jacking pipe x continues to rotate and advance, and drilling is completed by cutting down to the left and right sides of the hole cover plate 7.

[0033] Figure 16 is a cross-sectional view showing the arrival of the jacking pipe, showing the state in which the jacking pipe x enters from the right side of the figure. Figure 17 is a cross-sectional view taken along the DD line of the same figure. Until the drilling is complete, the jacking pipe x enters the pipe insertion hole 9 of the watertight rubber 3. The lubricant filled in the pipe insertion hole 9 comes out onto the surface of the watertight rubber 3, reducing friction between the jacking pipe x and the watertight rubber 3. However, as the sawtooth tip of the jacking pipe x rotates and comes into contact with the outer watertight rubber 3a, cracks may occur in the outer watertight rubber 3a that comes into contact with it. These cracks may progress through the outer watertight rubber 3a in the thickness direction and reach the opposite surface. However, since the inner watertight rubber 3b is a sheet independent of the outer watertight rubber 3a, cracks will not progress to the inner watertight rubber 3b. Therefore, the outer watertight rubber 3a also functions as a protective sheet for the inner watertight rubber 3b.

[0034] Because the pipe insertion hole 9 is smaller than the outer shape of the jacking pipe x, the jacking pipe x enters while pushing the rubber sheet near the pipe insertion hole 9 into the inside of the earth-retaining pipe 1 for forming the arrival tunnel. The protective sheet 4 is a plain-woven glass fiber fabric that can be easily cut with a blade, so it is broken through by the tip of the jacking pipe x. The portion of the rubber sheet near the pipe insertion hole 9 then bends to wrap around the side of the jacking pipe x, and this portion becomes a water-stopping section. In this way, a water-stopping section can be formed simply by inserting the jacking pipe x into the earth-retaining pipe 1 for forming the arrival tunnel, preventing groundwater and soil from flowing into the earth-retaining pipe 1 for forming the arrival tunnel from the point where the jacking pipe x enters.

[0035] Once the pipe x has penetrated deep enough to form a sufficient watertight section, the rotation and advancement of the pipe x is stopped. Because the watertight rubber 3 is attached along the inner surface of the tubular member 2, a long distance remains between the tip of the pipe x and the inner surface of the tubular member 2, ensuring a large working space. In this way, the pipe x and the arrival hole 22 are connected.

[0036] Next, buried pipes (main pipes) 24, 25 are passed through the retaining pipe 1 for forming the arrival tunnel and the propulsion pipe x in two directions, vertically and horizontally. A horizontal buried pipe 24 is introduced from the starting tunnel 20 through the propulsion pipe x to the retaining pipe 1 for forming the arrival tunnel. A vertical buried pipe 25 is introduced from above the arrival tunnel 22. A drop bend bent at 90° is provided at the bottom end of the vertical buried pipe 25 so that it can be connected to the tip of the horizontal buried pipe 24. The ends of these two buried pipes 24, 25 are connected inside the retaining pipe 1 for forming the arrival tunnel, and this work can be done without anyone entering the pipe. A worker above the arrival tunnel 22 holds the upper side of the vertical buried pipe 25 and adjusts the position and orientation of its lower end, then pushes the horizontal buried pipe 24 out of the starting tunnel 20 and connects its tip to the bottom end of the vertical buried pipe 25. This work requires a large working space, but according to the present invention, the necessary working space can be obtained even with a thin earth retaining pipe for forming an access tunnel.

[0037] After the buried pipes 24, 25 are connected to each other, filler is poured from above the arrival tunnel 22 and poured between the jacking pipe x and the buried pipe 24. On the starting tunnel 20 side, the end of the jacking pipe x is capped, sealing the space between the jacking pipe x and the buried pipe 24. The pouring of filler is stopped once the space is completely filled. It is preferable to insert the jacking pipe x to a certain length so that it protrudes into the tubular member 2. By connecting the tubular member 2 and the jacking pipe x together in this manner and solidifying the connection by pouring in filler, the tubular member 2 and the jacking pipe x move as a unit in the event of shaking such as an earthquake, and no force is applied that would deform the connection between the buried pipes 24, 25. This prevents the connection between the buried pipes 24, 25 from being damaged by vibrations such as an earthquake, resulting in water leakage.

[0038] In this way, an underground pipeline is formed that continues from the top of the arrival shaft 22 to the departure shaft 20. It does not affect construction even if there is an obstacle such as a waterway between the departure shaft 20 and the arrival shaft 22, or in any ground conditions. Furthermore, since there is no need for workers to enter the arrival shaft 22, construction can be carried out even in a small vertical shaft that is too small for a person to enter. [Explanation of symbols]

[0039] 1. Retaining pipe for forming the arrival tunnel 2. Tubular members 3.Waterproof rubber 4. Protective sheet 5.Waterstop rubber support member 6. Hole 7. Hole cover plate 8. Cylindrical member (main body of tubular member) 9. Pipe insertion hole 10. Soil cutting member 11. Lubricants 12. Bolt holes 20. Departure Tunnel 21. Propulsion machinery 22.Achievement pit 23. Shaft-forming propulsion machine 24. Horizontal buried pipes 25.Vertical buried pipes x. Propulsion pipe (sheath pipe)

Claims

1. A retaining pipe for forming an access tunnel, comprising a tubular member, a plurality of water-stopping rubbers stacked on the inner surface of the tubular member, a protective sheet provided on the inner surface of the innermost water-stopping rubber of the tubular member, a water-stopping rubber support member that supports the water-stopping rubbers and the protective sheet, and a soil cutting member provided at the tip of the tubular member, wherein a pipe insertion hole is formed in the water-stopping rubber.

2. The retaining pipe for forming an access tunnel as described in claim 1, wherein the water-stopping rubber has an outer water-stopping rubber that contacts the inner surface of the tubular member and an inner water-stopping rubber that is arranged inside the outer water-stopping rubber, and the inner water-stopping rubber is thicker than the outer water-stopping rubber.

3. A retaining pipe for forming an access tunnel as described in claim 1 or claim 2, wherein the tubular member has a cylindrical main body, a hole provided on the side of the main body, and a hole covering member provided on the outer surface of the main body to cover the hole, and the water-stopping rubber is attached to the inner surface of the hole covering member.

4. 4. An underground pipeline construction method using the retaining pipe for forming an arrival pit according to claim 3, wherein the retaining pipe for forming an arrival pit is driven vertically into the ground while rotating to form an arrival pit; A sheath tube having a soil cutting member at its tip and an outer diameter larger than the inner diameter of the tube insertion hole of the watertight rubber is rotated and sent from the starting tunnel side toward the arrival tunnel, While rotating the sheath pipe, the sheath pipe is brought into contact with the retaining pipe for forming the arrival hole, and the hole covering member is cut with the tip of the sheath pipe; The sheath pipe is inserted into the pipe insertion hole of the watertight rubber to form a watertight section with the watertight rubber, and the sheath pipe is connected to the retaining pipe for forming the arrival pit. An underground pipeline construction method in which the main pipe is sent from the starting tunnel to the arrival tunnel through a sheath pipe, forming an underground pipeline from the starting tunnel to the arrival tunnel.

Images