JP4527158B2 - Leakage recovery device in submersible construction method - Google Patents

Description

  The present invention relates to a leak recovery apparatus in a submerged method.

  As a construction method used for construction of a pier foundation, etc., a submerged construction method in which a caisson is set in the bottom of the water is known. In the submersion method, a blade piercing part that penetrates the ground is provided at the lower end of the cylindrical caisson body, a ceiling slab is formed on the inner peripheral side of the caisson body, and a caisson is formed on the inner peripheral side of the blade throat and below the ceiling slab. While separating the work chamber and supplying compressed air to the caisson work chamber, the internal ground is excavated and the caisson main body is set in the ground.

  In this case, a part of the compressed air supplied into the caisson work chamber can easily leak through the tip of the caisson main body and leak to the outside. It will erupt to an unexpected place through the water permeable layer inside and adversely affect adjacent structures.

Therefore, in the past, an air leakage recovery device was provided on the outer surface directly above the blade edge of the caisson body, but the recovery efficiency was poor. As a method for increasing the recovery efficiency, as disclosed in Patent Document 1, a leak recovery filter is formed around the outer edge of the caisson body so as to circulate, and a pumping pipe is connected to the leak recovery filter from the inside of the caisson body. , And by operating a pumping means such as a vacuum pump connected to the other end of this pumping pipe, leak the leaked air leaking outside through the tip of the caisson body from the caisson working room. There has been proposed an air-leakage recovery device that is inhaled and recovered by a filter.
JP 2002-88770 A

  However, in the above air leakage recovery apparatus, since the vacuum pump as the pumping means has to be prepared individually, there is a problem that the configuration of the air leakage recovery apparatus becomes complicated.

  The present invention has been made in view of such circumstances, and with a simple configuration, it is possible to collect leakage leaked outward from the caisson work chamber, preferably air and groundwater contained in the leakage. It is an object of the present invention to provide a leak recovery device in a submerged construction method that can be reliably separated and reduced, and further can suppress the amount of leak.

  In order to solve such a problem, the invention according to claim 1 of the present invention is provided with a blade opening portion penetrating into the ground at the lower end of the outer peripheral wall of the cylindrical caisson body, and on the inner peripheral side of the outer peripheral wall. Forming a ceiling slab, separating a caisson working chamber on an inner peripheral side of the blade edge portion and below the ceiling slab, and excavating the internal ground while supplying compressed air to the caisson working chamber; In the leak recovery device in the submerged construction method in which the main body is set in the ground and the compressed air leaked outside through the blade opening from the caisson working chamber is opened to the outer peripheral surface of the caisson main body. A leak recovery hole, a leak recovery passage having one end connected to the leak recovery hole and the other end communicating to the atmosphere, and an air supply passage having one end connected to a portion of the leak recovery passage close to the leak recovery hole And connected to the other end of the air supply passage. Characterized in that the air leakage recovery device in caisson method comprising a compressed air blowing means.

  Further, the invention according to claim 2 of the present invention, in addition to the configuration according to claim 1, is a leakage in a submerged construction method in which the leak collection holes are arranged at a plurality of locations along the horizontal direction of the outer peripheral surface of the caisson body. It is characterized by being a gas recovery device.

  Furthermore, the invention according to claim 3 of the present invention is the leak recovery apparatus in the submerged method, in addition to the configuration according to claim 1, wherein groundwater reduction means is provided at the end of the leak recovery passage at the atmosphere communication side. It is characterized by that.

  The invention according to claim 4 of the present invention, in addition to the configuration according to claim 3, separates the groundwater reduction means from the groundwater flowing into the leak recovery passage and the leak, It is characterized by having a leak recovery device in a submerged construction method in the basement as a separation storage tank for reducing the leak to the atmosphere.

  Further, the invention according to claim 5 of the present invention, in addition to the configuration according to claim 3, the groundwater reduction means, the air communication side end of the leak recovery passage is located on the ceiling slab of the caisson main body. It is set as the air leak collection | recovery apparatus in the submerged construction method opened on the water surface of the load water storage part provided in this.

  Furthermore, in the invention described in claim 6 of the present invention, in addition to the configuration described in any one of claims 1 to 5, the leakage of the compressed air is detected at the end of the leakage communication passage at the atmosphere communication side end. The leak detection device in the submerged construction method is provided with a leak detection device that performs the above and an alarm device that issues an alarm in conjunction with the operation of the leak detection device.

  Further, the invention according to claim 7 of the present invention is a submerged method in which in addition to the structure according to any one of claims 1 to 6, clogging prevention means for preventing clogging of earth and sand is provided in the leak recovery hole. It is characterized by having set it as the air leak collection | recovery apparatus in.

  Furthermore, the invention according to claim 8 of the present invention is a submersible that also uses compressed air supply means for supplying compressed air into the caisson work chamber as the compressed air supply means in addition to the configuration according to claim 1. It is characterized by being a leak recovery device in the construction method.

  According to the first aspect of the present invention, compressed air is supplied from the air supply passage to the leakage recovery passage by the compressed air supply means, thereby generating a negative pressure in the leakage recovery hole and leaking outside the caisson. Since air is sucked and collected from the air leakage collection hole, the compressed air supply means conventionally provided for supplying the compressed air to the caisson working chamber can be used as it is as the compressed air supply means. It is no longer necessary to separately prepare equipment such as a vacuum pump, and air leakage leaked outward from the caisson work chamber can be reliably recovered with a simple configuration.

  According to the invention which concerns on Claim 2, leak can be collect | recovered more efficiently with the multiple leak collection holes provided.

  According to the invention which concerns on Claim 3, the ground water reduction means can isolate | separate and reduce the air and ground water which are contained in the air leak.

  According to the invention which concerns on Claim 4, it can isolate | separate and reduce | restore more reliably the air and groundwater which are contained in the air leak by simple structure.

  According to the invention which concerns on Claim 5, the height of the air | atmosphere communication side edge part of an air leak collection | recovery channel | path can be made low, a lift can be lowered | hung, and extraction of groundwater and an air leak can be made easy.

  According to the sixth aspect of the invention, since an alarm is issued at the same time as air leakage is detected, if the amount of compressed air supplied to the caisson work chamber is reduced in conjunction with this, leakage from the caisson can be achieved. The amount of qi can be minimized.

  According to the invention which concerns on Claim 7, the clogging of the air leak collection | recovery hole can be prevented, and the air leak collection | recovery property outside a caisson can be improved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[Embodiment 1]

  FIG. 1 is a longitudinal sectional view of a caisson body 11 to which an air leakage recovery apparatus 10 according to Embodiment 1 of the present invention is applied. FIG. 2 is a plan view taken along the arrow II in FIG. It is the longitudinal cross-sectional view which expanded the III section of FIG.

  The caisson main body 11 is generally formed of reinforced concrete in a cylindrical shape, and a blade edge portion 14 is provided at the lower end of the outer peripheral wall 12 forming the outer peripheral portion thereof, and a horizontal plane ceiling slab 15 is provided on the inner peripheral side of the outer peripheral wall 12. A caisson working chamber 16 is formed below the ceiling slab 15 and on the inner peripheral side of the blade edge portion 14.

  In the first embodiment, the caisson main body 11 is formed in a square shape in the horizontal cross section, but may be a round shape, an oval shape, a triangle shape, a polygonal shape, or the like. The blade opening portion 14 has a wedge-shaped cross section that increases in thickness as it goes upward from the tip portion and toward the middle of the caisson main body 11.

  An air supply pipe 17 is connected to the caisson working chamber 16 from the outside, and compressed air supply means such as an air compressor 18 is connected to the outer end side of the air supply pipe 17. The portions indicated by reference numerals 19 and 20 in the figure are manlocks and material locks whose lower ends are connected to the caisson working chamber 16.

  In the submerged method, the caisson main body 11 formed in this way is inserted into the ground G with its blade edge portion 14 and the compressed air of the air compressor 18 is supplied into the caisson working chamber 16 from the air supply pipe 17. The ground G inside the caisson working chamber 16 is excavated by an unillustrated excavator installed inside the chamber 16, and the caisson main body 11 is submerged in the ground G by its own weight and finally enters the ground G as a foundation of a bridge pier or the like. Embed deeply. In addition, in order to increase the weight of the caisson body 11 and set it against the lifting pressure in the ground G, the load water 21 is often stored on the ceiling slab 15 of the caisson body 11.

  The air leakage recovery device 10 includes an air leakage recovery hole 24, an air leakage recovery passage 25, an air supply passage 26, a compressed air supply means, a groundwater reduction means, and the like. As the compressed air supply means, the above-described air compressor 18 is also used.

  As shown in an enlarged view in FIG. 3, the air leakage collection hole 24 opens to the outer peripheral surface that is about 0.1 m to 3 m above the lower end of the blade opening 14 of the caisson body 11, such as earth and sand. A filter 28 is fitted as a clogging prevention means for preventing clogging. The filter 28 can prevent clogging of the earth and mud when the ground G is excavated in the caisson working chamber 16 in the air leakage collection hole 24 and improve the air leakage recovery performance.

  The air leakage collection passage 25 is formed near the outer surface inside the outer peripheral wall 12 by, for example, embedding a metal pipe in the vertical direction, and one end (lower end) of the air leakage collection passage 25 is bent outward at a right angle to form the air leakage collection hole 24. The other end communicates with the atmosphere at a position higher than the air leakage collection hole 24. In this embodiment, the air leakage collection passage 25 extends upward from the air leakage collection hole 24 to the inside of the outer peripheral wall 12 and extends upward from the upper end portion of the caisson main body 11.

  The air leakage collection holes 24 and the air leakage collection passages 25 are arranged at a plurality of locations along the horizontal direction of the outer peripheral surface of the caisson main body 11. In the present embodiment, the air leakage recovery holes 24 and the air leakage recovery are made at a total of 8 locations including the corners of the caisson body 11 (outer peripheral wall 12) formed in a square cross section and the intermediate portions of the four sides of the outer peripheral wall 12. The passages 25 are provided at equal intervals, but this number increases or decreases depending on the size of the caisson main body 11 and is not limited to only eight places. In addition, the number of the air leakage collection holes 24 may be increased by arranging the air leakage collection holes 24 at a plurality of locations along the horizontal direction of the outer peripheral surface of the caisson main body 11 in this manner and also by providing multiple stages in the vertical direction. .

  The upper ends of the eight air leak collection passages 25 communicate with the air leak connection pipes 30 that are annularly arranged at the upper part of the caisson main body 11. The air leakage connection pipe 30 is formed in a square annular shape along the shape of the upper opening of the caisson main body 11, and the upper ends of the eight air leakage recovery passages 25 are formed at the corners formed by the four sides and at the middle of each side. Connected. One side of the air leakage connection pipe 30 extends horizontally as a air leakage extension pipe 30a, and the free end of the air leakage extension pipe 30a is open to the atmosphere. In addition, without providing the air leakage connection pipe 30, the air leakage collection passages 25 are gathered inside the caisson main body 11 and collected into one, and the collected pipes are drawn out of the caisson main body 11 to communicate with the atmosphere. It is good also as a structure.

  A storage tank 31 for separation as groundwater reduction means is connected to the air leakage extension pipe 30a. The separation storage tank 31 is configured in the form of a gas-liquid separation tank, and a leakage extension pipe 30a is connected to one surface thereof, and an air reduction pipe 32 and a groundwater reduction pipe 33 extend from the opposite surface. An air leakage detection device 35 is connected to the air reduction pipe 32, and a buzzer 36 as an alarm means is further connected to the air leakage detection device 35.

  For this reason, the air leakage collection passage 25 communicates with the atmosphere via the air leakage connection pipe 30, the air leakage extension pipe 30 a, the separation storage tank 31, and the air reduction pipe 32.

  The air leak detection device 35 detects air flowing in the air leak extension pipe 30a toward the atmosphere opening side as air leak. When the air leak detection device 35 detects air leak, the buzzer 36 is activated and an alarm is issued. Instead of the buzzer 36, visual warning means such as a blinking lamp may be used.

  On the other hand, the air supply passage 26 is formed by embedding a metal pipe or the like in the vertical direction inside the outer peripheral wall 12 in the same manner as the air leakage collection passage 25. Eight air supply passages 26 are arranged in the same manner as the air leakage recovery passages 25, each of which is parallel to the inside of the air leakage recovery passage 25, and one end of each air supply passage 26 is connected to the adjacent air leakage recovery passage 25. It is connected to the vicinity of the lower end, that is, a portion close to the air leakage collection hole 24, and from there, the inside of the outer peripheral wall 12 extends upward along the inside of the air leakage collection passage 25, and the other end extends out of the caisson body 11. .

  The upper ends of the eight air supply passages 26 communicate with the air supply connection pipes 38 that are annularly arranged at the upper part of the caisson main body 11. Similarly to the air leakage connection tube 30, the air supply connection tube 38 is formed in a square annular shape along the shape of the upper opening of the caisson main body 11, and is disposed on the inner peripheral side of the air leakage connection tube 30 in plan view. The upper ends of the eight air supply passages 26 are connected to the corner portion formed by the four sides and the middle portion of each side.

  One side of the air supply connecting pipe 38 extends horizontally as an air supply extension pipe 38a, and the free end side of the air supply extension pipe 38a is connected to the air supply pipe 17, and finally to the air compressor 18 which is a compressed air supply means. It is connected. A flow rate adjustment valve 39 is connected to an intermediate portion of the air supply extension pipe 38a. In addition, without providing the air supply connecting pipe 38, the air supply passages 26 are gathered inside the caisson main body 11 and gathered into one, and the collected pipes are pulled out of the caisson main body 11 and connected to the air supply pipe 17. It is good also as composition to do.

  When performing submergence work using the caisson main body 11 provided with the air leakage recovery device 10 configured as described above, the compressed air of the air compressor 18 is supplied from the air supply pipe 17 into the caisson working chamber 16 as described above. The ground G inside the caisson working chamber 16 is excavated while being fed to the ground, and the caisson main body 11 is allowed to sink into the ground G by its own weight.

  Along with this operation, the groundwater W is accumulated in the caisson working chamber 16, and the water level of the groundwater W is adjusted by adjusting the pressure of the compressed air supplied from the air supply pipe 18. By increasing the pressure of the compressed air sent from the air compressor 18 and increasing the internal pressure of the caisson working chamber 16, the level of the groundwater W can be lowered and the excavation workability can be improved.

  However, when the water level of the groundwater W in the caisson working chamber 16 decreases, a part of the compressed air easily passes through the tip of the blade opening 14 and leaks to the outside. In this way, the air leaking from the caisson working chamber 16 to the outside is recovered by the air leak recovery device 10 as follows.

  That is, by opening the flow rate adjusting valve 39 of the air supply extension pipe 38a, a part of the compressed air of the air compressor 18 is distributed to the eight air supply passages 26 through the air supply extension pipe 38a and the air supply connection pipe 38. Compressed air is sent to the vicinity of the lower end of the leak recovery passage 25. Since groundwater naturally flows into the inside of the air leakage collection passage 25 from the air leakage collection hole 24, the compressed air is supplied from the air supply passage 26 to the vicinity of the lower end of the air leakage collection passage 25, thereby causing air leakage. The groundwater in the recovery passage 25 is pushed up and pumped upward, thereby forming a gas-liquid flow F (see FIG. 3) that flows upward in the leakage recovery passage 25, and negative pressure is applied to the leakage recovery hole 24. Will occur.

  For this reason, as indicated by an arrow in FIG. 1, the air (leakage) leaked outside through the tip of the blade opening 14 from inside the caisson working chamber 16 upward along the outer peripheral surface of the caisson 11. During the flow, the air is sucked into the air leakage collection hole 24, and the air thus sucked is mixed with the above-described gas-liquid flow F flowing upward through the air leakage collection passage 25, and the air leakage connection pipe 30 and the air leakage extension pipe 30a. And then flows into the separation reservoir 31.

  The gas-liquid flow that has flowed into the separation storage tank 31 is separated into water and air (leakage), the water is reduced to the ground via the groundwater reduction pipe 33, and the air is returned to the atmosphere via the air reduction pipe 32. Reduced.

  According to this air leak recovery device 10, it is possible to recover air leaked from the caisson work chamber 16 to the outside with a very simple configuration, and to reliably separate the air contained in the air leak from the groundwater. And can be reduced.

  In particular, since the air compressor 18 provided as the compressed air supply means for supplying the compressed air to the caisson working chamber 16 can be used as the compressed air supply means as it is, the air leakage is sucked in the conventional manner. There is no need to separately prepare equipment such as a vacuum pump for generating negative pressure, and air leakage can be reliably recovered with a very simple configuration.

  Moreover, since the air leak collection holes are arranged at a plurality of locations along the horizontal direction of the outer peripheral surface of the caisson 11, the air leak from the caisson working chamber 16 can be collected more efficiently.

  Further, since the separation storage tank 31 as the groundwater reduction means is connected to the leakage extension pipe 30a that is the end of the leakage collection passage 25 on the atmosphere communication side, the air contained in the leakage and the groundwater are reliably separated. The environmental damage that tends to occur during construction work can be minimized.

In addition, since the air leakage detection device 35 and the buzzer 36 are provided in the air reduction pipe 32 of the separation storage tank 31, when air flows through the air reduction pipe 32, it is immediately detected as air leakage by the air leakage detection device 35. Then, the buzzer 36 is activated and an alarm is issued. Therefore, if the amount of compressed air supplied to the caisson working chamber 16 is decreased in conjunction with this, air leakage from the caisson working chamber 16 can be minimized.

  FIG. 4 is a longitudinal sectional view of the caisson body 11 to which the air leak recovery apparatus 50 according to Embodiment 2 of the present invention is applied. Here, since the configuration other than the air leak recovery device 50 is the same as that of the first embodiment shown in FIG.

  The air leakage recovery device 50 includes an air leakage recovery hole 51, an air leakage recovery passage 52, an air supply passage 53, compressed air supply means, groundwater reduction means, and the like. The compressed air supply means is an air compressor 18.

  The shape, structure, installation position, etc. of the air leakage recovery hole 51 are the same as those of the air leakage recovery hole 24 of the air leakage recovery device 10 in the first embodiment.

  The air leakage collection passage 52 is formed of a metal pipe or the like, and its lower half is embedded in the outer peripheral wall 12, and its lower end is bent outward at a right angle and connected to the air leakage collection hole 51. Further, the portion above the middle portion of the air leakage collection passage 52 is bent inward at a right angle and extends upward after entering the load water storage portion 54 provided on the ceiling slab 15 of the caisson main body 11, and its tip. The opening 52a opens on the water surface of the load water 21 and communicates with the atmosphere.

  Thus, by opening the front end opening 52a of the air leakage recovery passage 52 on the water surface of the load water 21, the air leakage recovery passage 52 itself functions as a groundwater reduction means.

  As with the air supply passage 26 in the first embodiment, one end of the air supply passage 53 is connected to a portion near the air leakage recovery hole 51 of the air leakage recovery passage 52, and the upper end of the air supply passage 53 is connected to the caisson main body 11. It connects with the air supply connection pipe | tube 55 arrange | positioned circularly by the upper part. One side of the air supply connecting pipe 55 extends horizontally as an air supply extension pipe 55a, and the free end side of the air supply extension pipe 55a is connected to the air supply pipe 17, and finally to the air compressor 18 which is a compressed air supply means. It is connected. A flow rate adjusting valve 56 is connected to an intermediate portion of the air supply extension pipe 55a.

  When the flow rate adjusting valve 56 is opened, a part of the compressed air of the air compressor 18 is distributed to the eight air supply passages 53 through the air supply extension pipe 55 a and the air supply connection pipe 55, and the lower end of the air leakage recovery passage 52. Compressed air is sent in the vicinity. Since groundwater naturally flows into the inside of the air leakage collection passage 52 from the air leakage collection hole 51, the compressed air is supplied from the air supply passage 53 to the vicinity of the lower end of the air leakage collection passage 52. The groundwater in the recovery passage 52 is pushed up and pumped upward, whereby a gas-liquid flow that flows upward in the leakage recovery passage 52 is formed, and a negative pressure is generated in the leakage recovery hole 51.

  For this reason, as indicated by an arrow in FIG. 4, air (leakage) that leaks out from the caisson working chamber 16 through the tip of the blade edge portion 14 moves upward along the outer peripheral surface of the caisson 11. In the middle of the flow, the air is sucked into the air leakage collection hole 51, and the air thus sucked is mixed with the above-described gas-liquid flow that flows upward in the air leakage collection passage 52. The water is discharged from the tip opening 52a to the load water reservoir 54.

  The gas-liquid flow discharged to the load water reservoir 54 is separated into air and water, the water is stored as the load water 21 as it is in the load water reservoir 54, and the air is reduced to the atmosphere. Excess load water 21 in the load water reservoir 54 is discharged to the outside by a water pump (not shown).

  According to this air leak recovery device 50, since the air leak recovery passage 52 can be formed very short, the head (water head) of the gas-liquid flow flowing upward in the air leak recovery passage 52 can be reduced, and pumping is facilitated. be able to. Therefore, if the scale of the caisson main body 11 is the same, the leak recovery device 50 can recover leak with less energy (negative pressure) than the leak recovery device 10 in the first embodiment. .

  In addition, since the end of the air communication side of the air leakage collection passage 52 is opened on the surface of the load water 21, the air leakage collection passage 52 itself functions as the ground water reduction means. Therefore, it is necessary to separately provide a dedicated ground water reduction means. The leak recovery device 50 can be greatly simplified.

  In addition, in the leak recovery device 10 (50) of the first and second embodiments, as shown in a preferred example in FIG. 5, the connection in which the air supply passage 26 (53) is connected to the leak recovery passage 25 (52). The section 26a (53a) is inclined so as to rise from the lower end of the air supply passage 26 (53) toward the air leakage collection passage 25 (52), and the connection section 26a (53a) is leaked at an acute angle. If it merges with the passage 25 (52), the flow rate of the gas-liquid flow F flowing upward in the leak recovery passage 25 (52) is increased to increase the negative pressure generated in the leak recovery hole 24 (51). In addition, it is possible to dramatically improve the air leak recovery.

It is a longitudinal cross-sectional view of the caisson main body to which the air leak collection | recovery apparatus which concerns on Embodiment 1 of this invention was applied. It is a top view by the II arrow of FIG. It is the longitudinal cross-sectional view to which the III section of FIG. 1 which concerns on the same Embodiment 1 was expanded. It is a longitudinal cross-sectional view of the caisson main body to which the air leak collection | recovery apparatus which concerns on Embodiment 2 of this invention was applied. It is a longitudinal cross-sectional view which shows the more suitable example of Embodiment 1,2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Leak recovery apparatus 11 Caisson main body 12 Peripheral wall 14 Cutting edge 15 Ceiling slab 16 Caisson working room 17 Air supply pipe 18 Air compressor which is compressed air supply means 21 Load water 24 Leak recovery hole 25 Leak recovery path 26 Air passage 28 Filter 31 as clogging prevention means 31 Separation storage tank as groundwater reduction means 35 Leakage detection device 36 Buzzer as alarm device 54 Loaded water storage part G Ground W Groundwater

Claims (8)

Provided at the lower end of the outer peripheral wall of the cylindrical caisson body is a blade opening that penetrates the ground, and forms a ceiling slab on the inner peripheral side of the outer peripheral wall, and on the inner peripheral side of the blade opening and below the ceiling slab The caisson working chamber is separated from the caisson working chamber, the compressed air is supplied to the caisson working chamber, the internal ground is excavated, and the caisson body is set in the ground. In the air leak recovery device in the submersible construction method that recovers compressed air that leaks outside by diving,
Leak recovery hole that opens to the outer peripheral surface of the caisson body,
A leak recovery passage, one end of which is connected to the leak recovery hole and the other end of which is connected to the atmosphere;
An air supply passage connected at one end to a portion of the air leakage recovery passage close to the air leakage recovery hole;
Compressed air supply means connected to the other end of the air supply passage;
An air leakage recovery device in a submerged construction method, comprising:   2. The air leakage recovery device according to claim 1, wherein the air leakage recovery holes are arranged at a plurality of locations along a horizontal direction of the outer peripheral surface of the caisson body.   The leak recovery apparatus for a submerged method according to claim 1, wherein groundwater reduction means is provided at an end of the leak recovery passage on the atmosphere communication side.   The groundwater reduction means is a separation storage tank that separates groundwater and airflow flowing into the airflow collection passage, and reduces the groundwater to the ground and the airflow to the atmosphere. The air leak recovery device in the submersible construction method according to claim 3.   The groundwater reducing means is characterized in that an end portion on the atmosphere communication side of the air leakage collection passage is opened on a water surface of a load water storage portion provided on the ceiling slab of the caisson body. 3. A leak recovery device in the submersible construction method according to 3.   An air leakage detection device that detects leakage of the compressed air and an alarm device that issues an alarm in conjunction with the operation of the air leakage detection device are provided at the end of the air communication side of the air leakage collection passage. An air leakage recovery device in a submerged construction method according to any one of claims 1 to 5.   7. The leak recovery apparatus for a submerged construction method according to claim 1, wherein the leak recovery hole is provided with a clog prevention means for preventing clogging of earth and sand.   The leak recovery apparatus in a submerged construction method according to claim 1, wherein the compressed air supply means is also used as a compressed air supply means for supplying compressed air into the caisson work chamber.

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