Earth bucket fly-prevention structure for caisson and earth removal method

Abstract

To provide an earth bucket fly-prevention structure for caissons that can certainly prevent the incident of earth buckets' flying and a soil removal method applied in a pneumatic caisson construction method.SOLUTION: An earth bucket fly-prevention structure for caissons prevents an earth bucket from being pushed out with compressed air and then flying even when the compressed air in a high-pressure work space is released upon the encapsulating door of a material lock being damaged and flows into a material shaft. In the structure, the material shaft that is meant for an earth bucket transporting out the excavation soil excavated in the high-pressure work space to run through is a double-tube material shaft composed of an inner tube 2 and an outer tube 3. The aforesaid inner tube 2 of the double-tube material shaft has a slit part 2a formed on it that is capable of releasing the aforesaid compressed air from the inside of the shaft through the outside.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a structure for preventing the earth bucket of a caisson from flying away and a method for discharging earth in a pneumatic caisson construction method. [Background technology]

[0002] In the pneumatic caisson method, compressed air is sent into a high-pressure work chamber, and the soil excavated in the high-pressure work chamber is discharged to the outside using soil discharge equipment such as an earth bucket through a material shaft. In addition, when the earth bucket passes, a pair of upper and lower doors are opened and closed to allow for both the removal of soil and maintaining air pressure.

[0003] However, as the excavation depth increases with the pneumatic caisson method, the process of lifting the earth bucket from the high-pressure work chamber using the soil removal equipment becomes longer, and if the wire rope used to lift the earth bucket were to break, the height from which it would fall would also increase. In the worst case scenario, if the wire rope were to break, the earth bucket could fall from a high altitude with one of the material lock's two doors open, potentially destroying the door. In that case, the high air pressure inside the high-pressure work chamber could be suddenly released, flowing into the material lock, and the earth bucket loaded with soil could be pushed out of the material lock like a cannon, potentially resulting in a serious accident with serious consequences, potentially resulting in loss of life.

[0004] On the other hand, the exhaust noise and air leakage noise emanating from the material lock are loud, necessitating measures such as the installation of a sound-absorbing muffler. For example, Patent Document 1 discloses a material lock 9 having an airlock 17 provided between an upper hatch 15 and a lower hatch 16, with an air supply pipe 18 and an exhaust pipe 23 attached to the airlock 17, in which a sound-absorbing device for eliminating noise generated by the high-pressure air supplied from the air supply pipe 18 is provided in a substantially annular shape around the inside of the airlock 17 (see claim 1 in the scope of claims of Patent Document 1, paragraphs

[0023] to

[0044] of the specification, Figures 1 and 2 of the drawings, etc.).

[0005] Furthermore, Patent Document 2 discloses a material lock noise suppression device that has excellent sound-deadening and soundproofing functions, in which sufficient airtightness is obtained between the soundproof door and the cylindrical part in the noise suppression dome, the wire rope insertion holes provided in the noise suppression door are maintained at a substantially uniform size, an increase in the amount of air leakage is prevented, and the device can be made compact (see claim 1 in the scope of claims of Patent Document 1, paragraphs

[0023] to

[0032] of the specification, Figures 1 to 3 of the drawings, etc.).

[0006] However, the material lock with sound-absorbing function of Patent Document 1 and the sound-absorbing device of the material lock of Patent Document 2 are merely sound-absorbing devices that reduce the noise caused by air leakage, and are not designed to address the problem of the earth bucket flying off due to the wire rope being cut, as mentioned above, and naturally cannot prevent the earth bucket from flying off. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-143734 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-218790 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, the present invention was devised in consideration of the above-mentioned problems, and its purpose is to provide a caisson earth bucket flying prevention structure that can reliably prevent earth bucket flying accidents in double-tube material shafts, and a soil removal method in pneumatic caisson construction. [Means for solving the problem]

[0009] The earth bucket flying prevention structure for a caisson according to claim 1 is a structure for preventing an earth bucket from flying away even when the sealing door of the material lock is broken and the compressed air in the high-pressure work chamber is released and flows into the material shaft, and the material shaft through which the earth bucket for transporting excavated earth and sand in the high-pressure work chamber is inserted is a double-tube material shaft consisting of an inner tube and an outer tube, and the inner tube of the double-tube material shaft has a slit portion formed therein that communicates from inside the shaft to the outside and allows the compressed air to escape. It is characterized by:

[0010] The caisson earth bucket flying prevention structure of claim 2 is characterized in that, in the caisson earth bucket flying prevention structure described in claim 1, the slit portion is formed above the upper lock door of the sealing door.

[0011] The caisson earth bucket flying prevention structure of claim 3 is characterized in that, in the caisson earth bucket flying prevention structure of claim 1, the outer tube has an opening that connects from inside the shaft to outside the shaft and allows the compressed air to escape.

[0012] The earth removal method according to claim 4 is an earth removal method in a pneumatic caisson construction method, The material shaft for inserting an earth bucket to transport excavated soil and sand excavated in a high-pressure work chamber has the caisson earth bucket flying prevention structure described in any one of claims 1 to 3, and is characterized in that when the earth bucket is hoisted up and discharged, when the earth bucket passes through the upper lock door of the sealing door, the upper lock door is closed even when the lower lock door of the sealing door is closed. [Effects of the Invention]

[0013] According to the inventions of claims 1 to 4, even if the wire rope of the earth bucket is cut and the heavy earth bucket loaded with soil falls, damaging the sealing door of the material lock and releasing the compressed air in the high-pressure work chamber and flowing into the material shaft, it is possible to prevent a serious accident with the risk of death, such as the earth bucket loaded with soil being pushed out of the material lock like a cannon and flying out. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective side view that schematically shows the entire caisson shaft to which an earth bucket flying prevention structure for a caisson according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a perspective front view showing the double-tube shaft of the caisson shaft. [Figure 3] FIG. 3 is a plan view showing the double-tube shaft alone. [Figure 4] FIG. 4 is a perspective front view showing the slit shaft alone of the caisson shaft. [Figure 5] FIG. 5 is a plan view showing the slit shaft alone. [Figure 6] FIG. 6 is a perspective front view showing the exhaust shaft alone of the caisson shaft. [Figure 7] FIG. 7 is a horizontal cross-sectional view showing the exhaust shaft alone. [Figure 8]FIG. 8 is a schematic cross-sectional view showing the opening and closing operation of the sealing door when the caisson shaft is hoisted up and unloaded using a conventional soil unloading method. [Figure 9] FIG. 9 is a schematic cross-sectional view showing the accident situation when the wire rope of the caisson shaft is cut. [Figure 10] FIG. 10 is a schematic cross-sectional view showing the opening and closing operation of the sealing door when the caisson shaft is hoisted and unloaded using the soil unloading method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of a structure for preventing an earth bucket from flying off a caisson and a method for discharging earth according to the present invention will be described in detail with reference to the drawings.

[0016] [Caisson earth bucket flying prevention structure] (Caisson shaft) First, a caisson shaft 100 to which an earth bucket flying prevention structure 1 for a caisson according to an embodiment of the present invention (hereinafter simply referred to as earth bucket flying prevention structure 1) is applied will be described using Figure 1. Figure 1 is a perspective front view that schematically shows the entire caisson shaft 100 to which an earth bucket flying prevention structure 1 for a caisson according to an embodiment of the present invention is applied. Note that reference numeral 5 denotes a high-pressure working chamber 5.

[0017] The caisson shaft 100 described in this embodiment is a double-tube material shaft for bottom-mounted locking equipment, which has a large cross-sectional area and is composed of a cylindrical inner and outer tube with a locking section located at the bottom to accommodate deep depths. Of course, the earth bucket flying prevention structure for a caisson according to the present invention is not limited to double-tube material shafts for large-scale bottom-mounted locking equipment, but can also be applied to a single material shaft for a standard-sized caisson. However, at deep depths, the pressure inside the working chamber increases, making the problem of earth bucket flying more pronounced.

[0018] As shown in Figure 1, the caisson shaft 100 is a material shaft based on the double-tube shaft 10 (described below) of a double-tube type consisting of an inner tube 2 and an outer tube 3, and is a shaft for large-scale, deep caissons designed for a maximum operating pressure of approximately 0.9 MPa. Starting from the lower end connected to the caisson body 200, the caisson shaft 100 comprises a special shaft 11 with an inner flange structure that is installed in place of a heavy locking section when pouring concrete for the caisson, and a bottom door chamber 12 with a bottom door 12a. This bottom door 12a is a sealing door that seals off both the inner tube 2 and the outer tube 3.

[0019] The caisson shaft 100 is provided with a lower lock chamber 13 having a lower lock door 13a as a locking section, an intermediate lock chamber 14 that secures space between the lower lock door 13a and the upper lock door 15a, and an upper lock chamber 15 having an upper lock door 15a.

[0020] The lower lock door 13 a is a sealing door that seals the inner tube 2 , and the upper lock door 15 a is a sealing door that seals the inner tube 2 and the outer tube 3 .

[0021] As described above, the illustrated caisson shaft 100 is an example of a caisson shaft for deep excavation, and therefore, in anticipation of the wire rope being cut, which will be described in detail later, an intermediate door chamber 17 having an additional lock door 17a is provided in addition to the lower lock door 13a of the lock section described above. This additional lock door 17a is a sealing door that seals off the inner pipe 2 and outer pipe 3, just like the upper lock door 15a.

[0022] A slit shaft 16 and an exhaust shaft 16', which will be described in detail later, are installed continuously between this intermediate door chamber 17 and the upper lock chamber 15. Both the slit shaft 16 and the exhaust shaft 16' are shafts based on the double-tube shaft 10, and have slits formed therein that communicate from the inner pipe 2 to the outer pipe 3 to allow compressed air to escape when the wire rope is cut as described in the background art and an earth bucket (EB) falls, damaging the upper lock door 15a and allowing compressed air to flow into the inner pipe 2 from the high-pressure work chamber 5.

[0023] In addition, the exhaust shaft 16' has an opening 16a' formed in the outer pipe 3 that allows compressed air to escape from inside the double-tube shaft 10 to the outside. Reference numeral 16b' denotes a sound-absorbing muffler 16b' that reduces exhaust noise and air leakage noise, as described in the background art.

[0024] Furthermore, above the intermediate door chamber 17, a unit shaft 18 is provided, which has a bracket portion 18b on the outer periphery of the double-tube shaft 10 on which various units 18a required for the operation of the locking portion are mounted. Above the unit shaft 18, the aforementioned slit shaft 16 is provided, and above the slit shaft 16, two stages of double-tube shafts 10 are provided.

[0025] Moreover, above the two-stage double-tube shaft 10 that forms the upper part of the caisson shaft 100, the above-mentioned exhaust shaft 16' is provided.

[0026] At the top of the caisson shaft 100, an upper shaft 19 is provided, on which a hydraulic unit 19a and operating equipment are installed, and a landing 19b is formed around this upper shaft 19.

[0027] (double-tube shaft) Next, the double-tube shaft 10, which is a general shaft of the aforementioned caisson shaft 100, will be described in detail using Figures 2 and 3. Figure 2 is a perspective front view showing the double-tube shaft 10 alone of the caisson shaft 100, and Figure 3 is a plan view showing the double-tube shaft 10 alone.

[0028] 2 and 3, the double-tube shaft 10 includes a cylindrical inner tube portion 20 made of a 6 mm thick steel plate that constitutes the inner tube 2, an upper flange 21 made of a 75 mm wide, 19 mm thick flat bar welded to the upper end of the inner tube portion 20, and a lower flange 22 made of a 75 mm wide, 19 mm thick flat bar welded to the lower end of the inner tube portion 20. In the double-tube shaft 10 according to this embodiment, the inner tube portion 20 has a height of 2000 mm and an inner diameter D1 of 1200 mm.

[0029] As shown in Fig. 3, the upper flange 21 and the lower flange 22 are each provided with a plurality of bolt holes 21a (22a) for bolting to another shaft. Also, as shown in Figs. 2 and 3, the upper flange 21 and the lower flange 22 are joined perpendicularly to the inner cylindrical portion 20 via flange ribs 23 and 24 that serve as stiffening members.

[0030] Furthermore, the double-tube shaft 10 is equipped with a cylindrical outer tube portion 30 made of a 12 mm thick steel plate, an upper flange 31 made of a 90 mm wide, 25 mm thick flat bar welded to the upper end of the outer tube portion 30, and a lower flange 32 made of a 90 mm wide, 25 mm thick flat bar welded to the lower end of the outer tube portion 30. The outer tube portion 30 is set to a height of 2000 mm and an outer diameter D2 of 2332 mm.

[0031] As shown in Figure 3, the upper flange 31 and the lower flange 32 each have a plurality of bolt holes 31a (32a) for bolting to another shaft, and as shown in Figures 2 and 3, the upper flange 31 and the lower flange 32 are joined perpendicular to the outer tube portion 30 via flange ribs 33 and 34 which serve as stiffening materials.

[0032] The double-tube shaft 10 has an outer tube 3, which is the doughnut-shaped space between the inner tube 20 and the outer tube 30, and this outer tube 3 has a vertical ladder 35 for ascending and descending.

[0033] Reference numeral 36 denotes a lifting fitting 36 made of a 16 mm thick steel plate for hanging shackles etc. when assembling the caisson shaft 100 and lifting the double-tube shaft 10. Reference numeral P denotes various piping P installed in the outer pipe 3, and reference numeral 37 denotes a shaft connecting member 37 made of a 4 mm thick steel plate that connects the inner cylindrical portion 20 and the outer cylindrical portion 30 of the double-tube shaft 10.

[0034] (Slit shaft) Next, the slit shaft 16 of the caisson shaft 100 described above will be explained using Figures 4 and 5. Figure 4 is a perspective front view showing the slit shaft 16 of the caisson shaft 100 alone, and Figure 5 is a plan view showing the slit shaft 16 alone. The slit shaft 16 according to this embodiment differs from the double-tube shaft 10 described above mainly in that it has eight support columns 20' erected at a predetermined pitch instead of the inner cylindrical portion 20, so this point will be mainly explained, and the same components will be given the same reference numerals and explanations will be omitted.

[0035] As shown in Figures 4 and 5, the slit shaft 16 does not have an inner cylindrical portion 20. Instead, the upper flange 21 and the lower flange 22 are supported by eight support columns 20' made of 100 mm x 100 mm square steel pipes with a plate thickness of 6 mm, and the spaces between the support columns 20' form fully open slit sections 2a (see also Figure 6). Therefore, the slit shaft 16 is able to release compressed air from the inside of the shaft of the inner tube 2 to the outside through the slit sections 2a between the support columns 20'. Therefore, as will be described later, even if the wire rope lifting the earth bucket EB is cut and the earth bucket EB loaded with soil falls, destroying the lower lock door 13a due to the impact, the compressed air can escape from the inner tube 2 to the larger outer tube 3, reliably preventing the earth bucket EB from flying off.

[0036] As shown in Fig. 1, the slit shafts 16 are provided above the upper lock door 15a and the additional lock door 17a, respectively. Therefore, the slit portions 2a are formed above the upper lock door 15a and the additional lock door 17a, which are sealing doors, and in the unlikely event that the upper lock door 15a or the additional lock door 17a is damaged in an accident, the compressed air can escape from the inner pipe 2 to the outer pipe 3 directly above them (see also Fig. 9).

[0037] (exhaust shaft) Next, the exhaust shaft 16' of the caisson shaft 100 described above will be described using Figures 6 and 7. Figure 6 is a perspective front view showing the exhaust shaft 16' of the caisson shaft 100 alone, and Figure 7 is a horizontal cross-sectional view showing the exhaust shaft 16' alone. The main difference between the exhaust shaft 16' of this embodiment and the slit shaft 16 described above is that an opening 3a is formed in the outer cylindrical portion 30, so this point will be mainly described, and the same components will be given the same reference numerals and will not be described again.

[0038] As shown in Figures 6 and 7, a rectangular opening 3a measuring 639 mm x 1100 mm is formed in the outer cylinder portion 30 of the exhaust shaft 16', which allows compressed air to escape from the outer tube 3 to the outside of the shaft in the unlikely event that the upper lock door 15a or the additional lock door 17a is damaged in an accident (see also Figure 9).

[0039] This opening 3a is blocked from the outside by a 3 mm thick rubber plate 38. The upper part of this rubber plate 38 is bolted to the outer tube portion 30, and the lower part is magnetically attached to the outer surface of the outer tube portion 30 by a magnetic sheet 39. Therefore, when pressure is applied that exceeds the magnetic force of the magnetic sheet 39, the rubber plate 38 is free to open to the outside, and when compressed air flows in, it can be released from the outer tube 3 (outer tube portion 30) to the outside of the shaft.

[0040] [Earth removal method] Next, an earth removal method according to an embodiment of the present invention will be described with reference to Figs. 8 to 10. An example of earth removal using a caisson shaft 100 to which the earth bucket flying prevention structure 1 described above is applied will be described. Fig. 8 is a schematic cross-sectional view showing the opening and closing operation of the sealing door when the caisson shaft 100 is hoisted up and removed using a conventional earth removal method, and Fig. 9 is a schematic cross-sectional view showing the occurrence of an accident when the wire rope is cut. Also, Fig. 10 is a schematic cross-sectional view showing the opening and closing operation of the sealing door when the caisson shaft 100 is hoisted up and removed using the earth removal method according to an embodiment of the present invention.

[0041] As shown in Figure 8, in the conventional earth removal method, in the operating conditions for opening and closing the sealing door when hoisting and discharging the earth from the caisson shaft 100, when earth is loaded into the earth bucket EB and the wire rope is hoisted up by a structural crane (not shown), which is an earth removal facility, the lower lock door 13a, which is the material lock, is closed and the upper lock door 15a is open, and the earth is then hoisted up and discharged by the structural crane. The reason for this is that the compressed air in the high-pressure work chamber is sealed off by the lower lock door 13a, so the pressurized state is maintained, and there is no interference with the work of hoisting the earth bucket EB and discharging the earth.

[0042] However, as mentioned in the background art, if a malfunction occurs in a structural crane or the like and the wire rope hoisting the earth bucket EB is cut, the earth bucket EB loaded with soil will fall, as shown in Figure 9, and the impact will destroy the lower lock door 13a, causing the high air pressure in the high-pressure work chamber to be suddenly released and flow into the inner pipe 2, and the earth bucket EB loaded with soil will be pushed out of the inner pipe 2 like a cannon and thrown into the air, causing an accident. In particular, small caissons such as slim caissons are constructed in relatively narrow, densely populated residential areas, and there was a notable problem that if an earth bucket were to fly out, it could result in a serious accident.

[0043] However, in the caisson shaft 100 according to this embodiment, as described above, the slit shaft 16 is formed with slit portions 2a that communicate from the inside of the inner pipe 2 to the external outer pipe 3 and allow compressed air to escape. Therefore, even if the wire rope hoisting the earth bucket EB is cut and the earth bucket EB loaded with soil falls, destroying the lower lock door 13a due to the impact, the compressed air can be released from the inner pipe 2 to the outer pipe 3, which is a larger space, and can also be released outside the shaft through the opening 3a of the exhaust shaft 16'. Therefore, the earth bucket flying prevention structure 1 can reliably prevent the earth bucket EB from flying away.

[0044] Furthermore, in the earth removal method according to the embodiment of the present invention, as shown in Figure 10, when the caisson shaft 100 is hoisted and earth is removed, the sealing door closes the lower lock door 13a, and then when the earth bucket EB passes through the upper lock door 15a, the upper lock door 15a also closes. Therefore, even if the upper lock door 15a is destroyed in the unlikely event that the wire rope lifting the earth bucket EB is cut, the lower lock door 13a can prevent the high air pressure in the high-pressure work chamber from flowing into the inner pipe 2.

[0045] In the earth removal method according to this embodiment, when the earth bucket EB passes, the newly added additional lock door 17a is also closed in addition to the upper lock door 15a. This is because it is possible to further reduce the probability of an accident in which the earth bucket EB is thrown. However, the additional lock door 17a does not have to be closed. This is because closing the upper lock door 15a and the lower lock door 13a already provides double locking, which functions satisfactorily as a fail-safe.

[0046] In the structure 1 for preventing the earth bucket from flying away according to the embodiment of the present invention described above, the slit shaft 16 is formed with the slit section 2a and the exhaust shaft 16′ is formed with the opening 3a, so even if the wire rope for hoisting the earth bucket EB is cut and the earth bucket EB loaded with soil falls, destroying the lower lock door 13a due to the impact, the compressed air can be released from the inner pipe 2 into the larger space of the outer pipe 3 and outside the shaft, thereby reliably preventing the earth bucket EB from flying away.

[0047] Furthermore, in the earth removal method according to an embodiment of the present invention, when the caisson shaft 100 is hoisted and earth is removed, the lower lock door 13a is closed, and then when the earth bucket EB passes through the upper lock door 15a, the upper lock door 15a also closes. Therefore, even if the upper lock door 15a is destroyed, the lower lock door 13a can prevent the high air pressure in the high-pressure work chamber from flowing into the inner pipe 2.

[0048] The above has described in detail the earth bucket flying prevention structure 1 for a caisson according to an embodiment of the present invention and the earth removal method using the same. However, the above-mentioned and illustrated embodiments are merely specific embodiments for carrying out the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these. [Explanation of symbols]

[0049] 100: Caisson shaft (material shaft) 200: Caisson body EB: Earth bucket P: Piping 1: Earth bucket (caisson) flying prevention structure 10: Double tube shaft 11: Special shaft 12: Bottom door chamber 12a: Bottom door 13: Lower lock room 13a: Lower lock door (sealing door for material lock) 14: Intermediate lock chamber 15: Upper lock room 15a: Upper lock door (sealing door for material lock) 16: Slit shaft 16': Exhaust shaft 16a': opening 16b': Silencer muffler 17: Intermediate door chamber 17a: Additional lock door 18: Unit shaft 18a: Unit 18b: Bracket part 19: Upper shaft 19a: Hydraulic unit 19b:Landing 2: Inner tube 2a: Slit section 20: Inner cylinder 20': Post 21: Upper flange 21a: Bolt hole 22: Lower flange 23,24: Flange rib 3:Outer tube 30: Outer cylinder 3a: opening 31: Upper flange 31a: Bolt hole 32: Lower flange 33,34: Flange rib 35: Vertical ladder 36: Hanging hardware 37: Shaft connector 38: Rubber plate 39:Magnetic sheet 5: High-pressure work chamber

Claims

1. A caisson earth bucket flying prevention structure that prevents the earth bucket from being pushed out by the compressed air and flying away even if the sealing door of the material lock is broken and the compressed air in the high-pressure work chamber is released and flows into the material shaft, The material shaft for inserting an earth bucket for transporting excavated soil excavated in the high-pressure work chamber is a double-tube material shaft consisting of an inner tube and an outer tube, The inner tube of the double-tube material shaft is formed with a slit portion that communicates from the inside of the shaft to the outside and allows the compressed air to escape. A caisson earth bucket flying prevention structure characterized by the above.

2. The slit portion is formed above the upper lock door of the sealing door. The earth bucket flying prevention structure for a caisson according to claim 1, characterized in that:

3. The outer tube has an opening formed therein that communicates from inside the shaft to outside the shaft and allows the compressed air to escape. The earth bucket flying prevention structure for a caisson according to claim 1, characterized in that:

4. A method for discharging soil in a pneumatic caisson construction method, The material shaft for inserting an earth bucket for transporting excavated soil in a high-pressure work chamber has the earth bucket flying prevention structure for a caisson according to any one of claims 1 to 3, When the earth bucket is hoisted up and discharged, if the earth bucket passes through the upper lock door of the sealing door, the upper lock door is closed even if the lower lock door of the sealing door is closed. A soil removal method characterized by the above.

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