JP2013124510A - Construction method for dam body cofferdam structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cofferdam structure that can cope with the buoyance that is acted associated with the water drainage work of an inner space in construction.SOLUTION: A step in which a planned opening position 4a of a through hole 2 on a dam body upstream face 3 is brought into water-tight contact with an opening 21 of a dome body 10 that is a cofferdam structure, and a step in which water is discharged in an inner space 21 of the dome body 10 while weights 50 are sequentially input into the inner space 25 are executed to construct the cofferdam structure.

Description

  The present invention relates to a construction method for a temporary closing structure of a dam dam body, and specifically relates to a technology for a temporary closing structure capable of coping with buoyancy acting in conjunction with drainage work in the interior during construction.

  Through holes in the dam body of the existing dam for the purpose of securing a sediment discharge path on the upstream side of the dam body, a new water discharge path for the purpose of increasing flood control capacity, or a small hydroelectric generator installation area The number of cases of building is increasing. Conventionally, when constructing a through-hole in an existing dam body, a large-scale temporary cut-off work has been carried out to reach the bottom of the water upstream of the dam body, and the inside of the cut-off structure has been dried up to drill the through-hole. It was. However, such a method has a problem that the temporary deadline structure becomes large and the construction period and construction cost increase. Therefore, as a technology that enables temporary closing of dam water areas at a small scale and low cost, for example, a temporary closing structure (Patent Document 1) in which a spherical water blocking wall is attached to the surface of the dam dam body is proposed. Has been.

JP 2004-263380 A

In the above-described conventional temporary cutoff structure technology, the underwater hemispherical water blocking wall is pressed against the dam dam body by water pressure, and a frictional force is generated between them. It is based on the premise that the water wall will be fixed. On the other hand, when such a conventional temporary closing structure is adopted in actual construction, the inventors have found that a hemispherical water blocking wall drained from inside has a much larger buoyancy than its own aerial weight. Has been obtained. Moreover, since this buoyancy is generated when draining the inside of the hemispherical water blocking wall before the above-mentioned friction force is sufficiently exerted, it is expected that the buoyancy is countered by the friction force. It is a danger.
On the other hand, when the peripheral part of the temporary closing structure is fixed by driving an anchor to the dam dam body around the through hole, when the large buoyancy as described above is applied to the temporary closing structure, the anchor receiving the buoyancy There is also a concern that the dam dam around the through hole may be damaged by the reaction force.
That is, in the prior art, countermeasures have not been sufficiently taken into account for buoyancy applied to the temporary closing structure during construction.

  Accordingly, an object of the present invention is to provide a technology of a temporary closing structure that can cope with buoyancy that acts in conjunction with drainage work of the interior sky during construction.

The construction method of the temporary closing structure in the dam dam body of the present invention that solves the above problems is a construction method of the temporary closing structure used in the construction of the through hole in the existing dam dam body, A step of bringing the opening of the dome body, which is a temporary closing structure, into a predetermined opening position in a watertight manner, and a step of sequentially throwing weights into the inner space while draining water in the inner space of the dome body. It is characterized by.
According to such a construction method, when draining the water inside the dome, the necessary amount of weight is sequentially thrown into the dome, corresponding to the buoyancy that increases with the progress of drainage, By balancing the buoyancy and the total weight of the dome body including the loaded weight, the force required to support the dome body can be minimized. Therefore, according to the present invention, it is possible to provide a temporary closing structure that can cope with buoyancy that acts in conjunction with drainage work in the interior during construction.

  In addition, in the construction method of the temporary closing structure in the dam dam body, when removing the temporary closing structure, a step of sequentially discharging the weight from the inner space while pouring water into the inner space of the dome body may be included. According to such a construction method, when removing the dome body, that is, the temporary closing structure, a necessary amount of weight is removed from the dome body space in response to the buoyancy that decreases as water is injected into the dome body space once dried up. Sequentially discharged and balances the buoyancy generated in the dome body at each time point with the total weight of the dome body including the weight remaining in the inner space, thereby preventing excessive weight from being applied to the temporary structure. I can do it.

In addition, the construction method of the temporary cutoff structure in the dam dam body of the present invention is a construction method of the temporary cutoff structure used when constructing the through hole in the existing dam dam body, and the planned opening position of the through hole on the upstream surface of the dam dam body And a step of watertightly contacting the opening of the dome body that is a temporary closing structure, and a step of sequentially holding weights on the outside of the dome body while draining water in the inner space of the dome body. It is characterized by.
According to such a construction method, when draining the water in the dome body, the necessary amount of weight is sequentially held outside the dome body corresponding to the buoyancy that increases with the progress of drainage, and occurs at each time point. By balancing the buoyancy and the total weight of the dome body including the held weight, the force required to support the dome body can be minimized. Therefore, according to the present invention, it is possible to provide a temporary closing structure that can cope with buoyancy that acts in conjunction with drainage work in the interior during construction.

  The construction method of the temporary closing structure in the dam dam body may include a step of sequentially removing weights from the outside of the dome body while water is poured into the inner space of the dome body when the temporary closing structure is removed. . According to such a construction method, when removing the dome body, that is, the temporary closing structure, a necessary amount of weight is attached to the outside of the dome body in response to the buoyancy that decreases as water is poured into the dome body once dried up. The buoyancy generated in the dome body at each point in time is balanced with the total weight of the dome body including the weight remaining outside the dome body, so that excessive weight is applied to the temporary structure. Can be deterred.

  Further, in the construction method of the temporary closing structure in the dam dam body, the weight is placed in the inner space so that the total weight of the weight and the dome body at a certain time point balances the buoyancy generated in the dome body at the corresponding time point. It is preferable to sequentially insert or hold the dome body sequentially outside the dome body, or to sequentially discharge the weight from the inner space or sequentially remove it from the outside of the dome body. According to such a construction method, when draining the water in the dome, the buoyancy that increases with the progress of the drainage is handled flexibly and reliably, and the buoyancy generated at each point in time and the total weight of the dome including the weight. By taking the balance, it is possible to minimize the force required to support the dome during this period.

  ADVANTAGE OF THE INVENTION According to this invention, the temporary closing structure which can cope with the buoyancy which acts with the internal drainage work at the time of construction can be provided.

It is a general view which shows the example of the temporary deadline structure in 1st Embodiment. It is a figure which shows the construction procedure 1 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 2 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 3 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 4 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 5 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 6 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 7 of the temporary closing structure in 1st Embodiment. It is a figure which shows the construction procedure 8 of the temporary closing structure in 1st Embodiment. It is a general view which shows the example of the temporary deadline structure in 2nd Embodiment. It is a figure which shows the construction procedure 4 of the temporary closing structure in 2nd Embodiment. It is a figure which shows the construction procedure 7 of the temporary closing structure in 2nd Embodiment.

--- First Embodiment ---
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall view showing a structural example of a temporary closing structure of a dam dam body in the first embodiment. The temporary closing structure 100 in the first embodiment is a temporary closing structure on the upstream side of the dam body, which is used in the construction of the through hole 2 such as a sand pit in the dam body 1 of the existing dam. As shown in FIG. 1, the temporary closing structure 100 according to the first embodiment includes a dome body 10 having a semi-elliptical structure whose cross section is convex on the upstream side of the dam dam body.

  The dome body 10 has an opening 21 that abuts the dam dam body upstream surface 3 via a water blocking material 7 and surrounds the planned opening position 4 a of the through hole 2. The opening 21 is a skirt portion 33 whose peripheral edge is appropriately extended. When the opening 21 comes into contact with the dam dam body upstream surface 3 through the water blocking material 7, the skirt portion 33 has the skirt dam body upstream surface. 3 is contacted. Further, an appropriate anchor material may be placed on the upstream surface 3 of the dam body so as to penetrate the skirt portion 33, and the dome body 10 may be temporarily fixed.

  An air supply valve 27 and a manhole 28 are provided on the upper outer periphery of the dome body 10, and a drain valve 29 is provided on the lower outer periphery. The air supply valve 27 is connected to an air supply device on the bank body 2 through an appropriate air supply path, and is a valve for guiding air to the inner space 25 of the dome body 10, that is, the temporary cutoff structure 100. The manhole 28 is an opening / closing port serving as an entrance / exit of a worker who performs work in the inner space 25 of the temporary closing structure 100. The manhole 28 includes a valve (not shown), and can be opened and closed between the inner space 25 and the outside of the manhole. The drain valve 29 is a valve for draining water from the inner space 25 of the temporary closing structure 100 to the outside.

  Further, the dome body 10 in the first embodiment includes an input pipe 31 (weight input path) for supplying the weight 50 from the predetermined position above the water surface of the water area (eg, on the bank body 1) to the inner space 25. A weight inlet 22 is provided for communicating the inlet pipe 31 inside and outside the dome body 10. Examples of the weight 50 include a granular steel material, a lead material, a stone material, a sand material, or a liquid metal that can slide or roll on an appropriate conveyance path such as the inside of the inclined input pipe 31 and has a specific gravity from water. It is possible to adopt a substance whose is greater than a certain level. The feeding pipe 31 serving as a weight feeding path may include a belt conveyor, a pressure feeding device, and the like for transporting the weight 50 from the dam body 1 to the inner space 25. The input pipe 31 may be a steel pipe connected, or may be a hose-like member formed of a synthetic resin such as canvas, synthetic fiber, or rubber, and having appropriate rigidity and flexibility. Good.

  The weight supply device 60 is connected to the charging pipe 31 on the dam body 1 and supplies the weight 50 to the charging pipe 31. The weight supply device 60 has a structure for storing the weight 50, and a mechanism for acquiring the stored weight 50 by a predetermined amount and putting it in the pipe of the charging pipe 31, and is operated by a predetermined worker. In response to an electric signal from the control device, the motor and hydraulic device in the mechanism described above are driven according to the value indicated by the electric signal, and a predetermined amount of weight 50 is supplied to the input pipe 31. Of course, such an operation of supplying the weight 50 to the input pipe 31 may be performed by the worker himself.

  Further, in the inner space 25 of the dome body 10, a partition plate 35 serving as an enclosure for accommodating the weight 50 falling from the input pipe 31 described above is erected, and the weight 50 is scattered in the inner space 25. To prevent you from doing. The weight 50 accommodated in the inner space 25 is later discharged out of the dome body from the weight discharge port 23 provided below the area surrounded by the partition plate 35. The weight discharge port 23 includes an opening provided on the outer periphery of the dome body 10 and a door structure that opens and closes the opening in a watertight manner. The door structure receives an electrical signal from a control device operated by an operator on the dam body 1, drives a motor or a hydraulic device to move the door to expose the opening, and is accommodated in an area surrounded by the partition plate 35. The weight 50 that has been discharged is discharged into the water below the dome body. Further, after the weight 50 is discharged, an electric signal from a control device operated by an operator on the bank body 1 is also received, and a motor or a hydraulic device is driven to move the door to close the opening in a watertight manner.

  Although details will be described later, in the temporary closing structure 100 of the first embodiment, the total weight of the weight 50 and the dome body 10 at each time point corresponds to draining water in the inner space 25 of the dome body 10. In order to balance the buoyancy generated in the dome body 10 at that time, the weight 50 is sequentially inserted into the inner space 25, while the temporary closing structure 100 is removed after the through hole 2 is constructed, The weights 50 are sequentially discharged from the inner space 25 in consideration of the balance between the buoyancy and the total weight. In FIG. 1, the work table ship 40, the pump 41, and the air supply hose 42 used in conjunction with the drainage work from the inner space 25 are shown for reference (these will be described later).

  Hereinafter, the construction procedure of the temporary closing structure 100 of the first embodiment and the construction procedure of the through hole 2 will be described in detail. 2-9 is a figure which shows each construction procedure 1-8 of the temporary closing structure in 1st Embodiment, respectively. First, as shown in FIG. 2, the dome body 10 is suspended from the upper part of the dam body by a crane 80, and reaches a place (on the temporary structure 70 underwater) where the discharge pipe 48 is located at the upstream side 3 of the dam body. Submerge (Procedure 1). In addition, a closed gate door body 49 (FIG. 9) of a discharge pipe outlet is placed in advance in the inner space 25 of the dome body 10, both of which are large in size and weight, and are transported integrally to the site. It is impossible. Therefore, after completion of the inspection at the factory, these are divided and transported to the construction site and assembled near the dam body (not shown). Further, the temporary structure 70 described above is installed in the temporary placement position of the dome body 10 in the ground 5 upstream of the bank body.

  Following the procedure 1, as shown in FIG. 3, watertight processing such as sandwiching and fixing between the opening 21 of the dome body 10 and the upstream surface 3 of the dam body with the waterstop material 7 in the temporary closing structure 100 is performed ( Procedure 2). At this time, the dome body 10 may be temporarily fixed by penetrating the skirt portion 33 of the dome body 10 and placing an anchor on the upstream surface 3 of the dam dam body.

  Subsequently, as shown in FIG. 4, the input pipe 31 is suspended from the dam body by a crane 81 and connected to the weight input port 22 of the dome body 10. An injection pipe 31 is installed in advance on the inner space 25 side of the dome body 10 through the weight insertion port 22. Therefore, by this connection, the inside and outside of the dome body 10 communicate with each other through the insertion port 31 via the weight insertion port 22. Further, the manhole pipe 8 is suspended from the dam body by the crane 81 and connected to the manhole 28 of the dome body 10, and other manhole pipes 8 are sequentially connected to the upper end of the manhole pipe 8 connected to the manhole 28 ( Procedure 3).

  In installing the input pipe 31 and the manhole pipe 8, a worker is placed with the work table ship 40 floating in the water area upstream of the bank body, and the input pipe 31 and the manhole pipe 8 suspended by the crane 81 are positioned. The operation is such as the connection between the weight insertion port 22 and the insertion pipe 31, the connection between the manhole 28 and the manhole pipe 8, and the connection between the injection pipes 31 and the manhole pipes 8. Further, the manhole pipe 8 and the charging pipe 31 are temporarily fixed to the dam body upstream surface 3 with an appropriate fall prevention material 9 such as a steel bar (in the figure, only the manhole pipe 8 is fixed by the fall prevention material 9. Shown).

  Next, as shown in FIG. 5, the air supply hose 42 is extended from the pump 41 installed on the work table ship 40 and connected to the air supply valve 27 of the dome body 10, and the dome body 10 is connected to the inner space 25. Supply of pressurized air is started (procedure 4). At the same time, the drain valve 29 of the dome body 10 is opened, and the water present in the inner space 25 of the dome body 10 is discharged along with the air filling by the above-mentioned supply air, thereby making the inner space 25 dry.

  Note that the buoyancy generated in the dome body 10 during drainage from the inner space 25 is much larger than the air weight of the dome body 10 when the drainage is completed. For example, the inventors have found that when a dome body 10 having an opening with a diameter of 10000 mm is installed at a water depth of 17 m, the buoyancy of about 18000 kN exceeds the air weight of the dome body 10. On the other hand, if the dome body 10 is pressed against the dam dam body upstream surface 3 by water pressure, a frictional force is generated between the dam body upstream surface 3 and the dome body 10 to reduce buoyancy. Is generated when the water in the inner space 25 is discharged before the above-described frictional force is sufficiently exerted, and therefore it is dangerous to expect to resist buoyancy by the above-described frictional force.

  Therefore, in the first embodiment, as a countermeasure against the buoyancy that increases with the progress of the drainage described above, the total weight of the weight 50 and the dome body 10 thrown into the inner space 25 by a certain point in time is the dome at the corresponding point. It is assumed that the weight 50 is sequentially inserted into the inner space 25 as the drainage proceeds so as to balance the buoyancy generated in the body 10. Therefore, a water level meter 6 is installed at an appropriate location in the inner space 25, and a predetermined amount of weight 50 is inserted from the weight supply device 60 according to the value of the water level in the inner space 25 indicated by the water level meter 6. The weight 50 is thrown into the inner space 25.

  If the water level value indicated by the water level gauge 6 falls below a predetermined reference value determined from the weights of the dome body 10 and the weight 50 that has been thrown in at that time, the above-mentioned balance is lost and upward force is exerted on the dome body 10. Therefore, a predetermined amount of weight 50 according to the difference between the water level value indicated by the water level gauge 6 and the predetermined reference value is additionally inserted into the inner space 25. As a result, the amount of the weight 50 in the inner space 25 is increased, and the buoyancy generated in the dome body 10 at the corresponding time is balanced with the total weight of the weight 50 and the dome body 10 in the inner space 25, thereby supporting the dome body 10. Can minimize the power required for

  On the other hand, if the water level value indicated by the water level gauge 6 rises above the predetermined reference value, the above-described balance is lost, and it can be sensed that the downward force is won as the force applied to the dome body 10, so Without continuing, the above drainage operation is continued. When the buoyancy increases due to the progress of the drainage, the above balance state is exceeded, and the water level value indicated by the water level gauge 6 falls below the predetermined reference value, the loading of the weight 50 is resumed.

  When air bubbles start to be ejected from the drain valve 29 of the dome body 10 during the above-described supply of pressurized air while continuing the drainage from the inner space 25 and the introduction of the weight 50, the air is completely discharged in the inner space 25. Since this means that the water has been drained, the drain valve 29 and the air supply valve 27 are closed, the valve of the manhole 28 is opened, the pressure air is gradually released, and the inner space 25 is set to atmospheric pressure. Thus, the inner space 25 becomes atmospheric pressure, and the dome body 10 is pressed against the upstream surface 3 of the dam body by water pressure, and is kept at the underwater position. Further, at this time, the work of throwing the weight 50 into the inner space 25 becomes unnecessary, and therefore the throwing pipe 31 outside the dome body 10 is removed after the weight throwing opening 22 is closed.

  When draining the water in the inner space 25, a submersible pump set in advance in the inner space 25 is operated with the above-described air supply valve 27 and drain valve 29 closed, and the upper end of the manhole pipe 8 is operated. Alternatively, a method of draining water may be employed.

  Subsequently, as shown in FIG. 6, a management corridor 43 is provided above the uppermost manhole pipe 8 among the connected manhole pipes 8. It enters the inner space 25 of the dome body 10 through the manhole tube 8 and the manhole 28 (procedure 5). The worker who enters the inner space 25 confirms that the inner space 25 is in a drained state. On the other hand, it is assumed that an appropriate excavator such as a loader 85 excavates the through hole 2 from the downstream side of the bank body. After confirming the drainage completion state of the inner air 25, the loader 85 performs excavation of a portion left between the inner air 25 of the dome body 10 and the drilled through hole 2.

  When this excavation is completed and the inner space 25 and the through hole 2 of the dome body 10 penetrate, the installation of the closed gate door body door 47 and the bell mouth 46 and the installation of the air pipe 45 are performed as shown in FIG. Installation is performed (procedure 6). In this case, the door 47 for the closed gate door body and the bell mouth 46 previously placed in the inner space 25 of the dome body 10 are installed on the bank body 1, and the discharge pipe 48 from the downstream side of the bank body in the through hole 2. The discharge pipe 48 is connected to the closed gate door body 49 and the bell mouth 46. Further, the closed gate door body 49 is connected to the door 47 for the closed gate door body and the bell mouth 46.

  After this connection is completed, concrete is placed in a predetermined region such as a gap between the discharge pipe 48 and the inner wall of the through hole 2. In addition, the worker who has been working in the inner space 25 of the dome body 10 is made to leave on the work table boat 40 on the water or the management corridor 43 through the manhole pipe 8.

  Subsequently, as shown in FIG. 8, the air supply valve 27 and the drain valve 29 are opened, and water is injected into the inner space 25 of the dome body 10 (procedure 7). At this time, the required amount of weight 50 is sequentially discharged from the inner space 25 through the weight discharge port 23 in response to the buoyancy that decreases as water is injected into the inner space 25. By balancing the buoyancy generated in the dome body 10 at each time point with the total weight of the dome body 10 including the weight 50 remaining in the inner space 25, it is possible to prevent an excessive weight from being applied to the temporary structure 70. Because. In this case, if the water level value indicated by the water level gauge 6 rises above a predetermined reference value, it can be detected that the above-described balance is lost and the downward force is won as the force applied to the dome body 10. A predetermined amount of weight 50 is discharged from the inner space 25 according to the difference between the water level value and the predetermined reference value.

  When the weight 50 is discharged from the inner space 25 via the weight discharge port 23, the door structure provided in the weight discharge port 23 has an electrical signal (water level meter) from a control device operated by an operator on the dam body 1. 6 is received in accordance with the difference between the water level value indicated by 6 and a predetermined reference value, and the door is moved by driving a motor or a hydraulic device to open the opening (lower part of the dome body 10). , The opening that exposes the region surrounded by the partition plate 35 in water is exposed, and the weight 50 accommodated in the region surrounded by the partition plate 35 is discharged into the water below the dome body. In addition, after discharging a predetermined amount of weight 50, the door structure described above receives an electrical signal from a control device operated by an operator on the dam body 1 and drives the motor or hydraulic device to move the door to open. Block water tightly. Thus, water is poured until the inner space 25 is filled with water while balancing the buoyancy generated in the dome body 10 at each time point with the total weight of the dome body 10 including the weight 50 remaining in the inner space 25. .

  Subsequently, as shown in FIG. 9, the manhole tube 8 connected to the manhole 28 is sequentially removed, and the dome body 10 in the temporary closing structure 100 is also lifted and removed by the crane 80 (procedure 8).

--- Second Embodiment ---
Next, the temporary cutoff structure 100 of 2nd Embodiment is demonstrated. FIG. 10 is an overall view showing an example of a temporary closing structure in the second embodiment. Note that the description of the same structure, function, etc. as in the first embodiment described above will be omitted. The dome body 10 in the temporary cutoff structure 100 illustrated here includes a hook 30 that holds the weight 50 outside the dome body 10. The hook 30 is a member composed of a bowl-shaped steel material or the like, and has a sufficient strength that does not break even if a predetermined number of weights 50 are held. The hook 30 is connected to a wire 32 (weight transport means) that transports the weight 50 from the top of the bank body 1. In this case, the weight 50 is provided with a ring 51 through which the wire 32 is inserted at the upper end, and slides while passing the wire 32 passed through the ring 51 with an inclination in the path from the top of the dam body 1 to the hook 30. You can move up to 30.

  Note that a heavy machine may be employed as the weight conveying means without connecting the wire 32 to the hook 30. In that case, the heavy machine on the bank 1 needs to hang the weight 50 to the hook 30 and hang the ring 51 on the hook 30.

  In the temporary closing structure 100 according to the second embodiment, the total weight of the weight 50 hung on the hook 30 and the dome body 10 at each time is drained while the water in the inner space 25 of the dome body 10 is drained. While the weight 50 is sequentially held by the hook 30 so as to balance the buoyancy generated in the dome body 10, the buoyancy and the total weight are also added while water is poured into the inner space 25 when the temporary closing structure 100 is removed after the through-hole 2 is constructed. The weight 50 is sequentially removed from the hook 30 in consideration of the balance with the weight.

  Hereinafter, contents different from those of the first embodiment described above will be described in the construction of the temporary closing structure 100 of the second embodiment and the procedure of construction of the through hole 2. FIG. 11 is a diagram showing a construction procedure 4 of the temporary closing structure in the second embodiment. Here, the description of “procedure 1” to “procedure 3” is omitted, and “procedure 4” is described.

  In this case, the air supply hose 42 is extended from the pump 41 installed on the work table ship 40 and connected to the air supply valve 27 of the dome body 10, and the supply of pressurized air to the inner space 25 of the dome body 10 is started. To do. At the same time, the drain valve 29 of the dome body 10 is opened, and the water present in the inner space 25 of the dome body 10 is discharged along with the air filling by the above-mentioned supply air, thereby making the inner space 25 dry. At this time, as a countermeasure to the buoyancy that increases with the progress of the drainage described above, the total weight of the weight 50 and the dome body 10 hung on the hook 30 up to a certain point is generated in the dome member 10 at the corresponding point. It is assumed that the weight 50 is sequentially held by the hook 30 as the drainage proceeds so as to balance with the above. Therefore, a water level meter 6 is installed at an appropriate location in the inner space 25, and a predetermined amount of weight 50 is applied to the wire 32 from the weight supply device 60 according to the value of the water level in the inner space 25 indicated by the water level meter 6. The weight 50 is hung on the hook 30 and held.

  If the water level value indicated by the water level gauge 6 falls below a predetermined reference value determined from the weight of the dome body 10 and the weight 50 already held at that time, the above-mentioned balance is lost and the upward force is applied to the dome body 10. Therefore, a weight 50 of a predetermined amount corresponding to the difference between the water level value indicated by the water level gauge 6 and the predetermined reference value is newly applied to the hook 30. As a result, the amount of the weight 50 held by the hook 30 is increased, and the buoyancy generated in the dome body 10 at the corresponding time is balanced with the total weight of the weight 50 held by the hook 30 and the dome body 10. The force required to support the body 10 can be minimized.

  On the other hand, if the water level value indicated by the water level gauge 6 rises above the predetermined reference value, it can be detected that the above-mentioned balance is lost and the downward force is won as the force applied to the dome body 10. No additional work is performed and the above drainage operation is continued. If the buoyancy increases due to the progress of the drainage, the above balance state is exceeded, and the water level value indicated by the water level gauge 6 falls below the predetermined reference value, the operation of additionally applying the weight 50 to the hook 30 is resumed.

  While continuing the drainage from the inner space 25 and the operation of applying the weight 50 to the hook 30, when air bubbles start to be ejected from the drainage valve 29 of the dome body 10 during the supply of the above-mentioned pressure air, the inner space 25, the drainage valve 29 and the air supply valve 27 are closed, the valve of the manhole 28 is opened, the pressure air is gradually released, and the inner space 25 is set to atmospheric pressure. Thus, the inner space 25 becomes atmospheric pressure, and the dome body 10 is pressed against the upstream surface 3 of the dam body by water pressure, and is kept at the underwater position. At this time, since the work of newly placing the weight 50 on the hook 30 is not necessary, the wire 32 connected to the hook 30 is removed.

  Next, “Procedure 7” indicating the removal work of the weight 50 will be described. FIG. 12 is a diagram illustrating a construction procedure 7 for the temporary closing structure according to the second embodiment. In this case, as shown in FIG. 12, the air supply valve 27 and the drain valve 29 are opened, and water is injected into the inner space 25 of the dome body 10. At this time, the required amount of weight 50 is sequentially removed from the hook 30 in response to the buoyancy that decreases with the progress of water injection into the inner space 25. In order to prevent excessive weight from being applied to the temporary structure 70 by balancing the buoyancy generated in the dome body 10 at each time point with the total weight of the dome body 10 including the weight 50 remaining on the hook 30. It is. In this case, if the water level value indicated by the water level gauge 6 rises above a predetermined reference value, it can be detected that the above-described balance is lost and the downward force is won as the force applied to the dome body 10. A predetermined amount of weight 50 is removed from the hook 30 according to the difference between the water level value and the predetermined reference value.

  When removing the weight 50 from the hook 30, gripping means (eg, a manipulator or the like) that grips the weight 50 with the hook 30, slides on the hook 30, and releases it to the outside of the hook is a work on the dam body 1. An electric signal (a signal indicating the number of removed weights 50 determined in advance according to the difference between the water level value indicated by the water level gauge 6 and the predetermined reference value) from a control device operated by an operator is received. The weight 50 hung on the hook 30 is discharged into the water below the dome body. In this way, water is poured until the inner space 25 is filled with water while balancing the buoyancy generated in the dome body 10 at each time point with the total weight of the dome body 10 including the weight 50 remaining on the hook 30. Such an operation of removing the weight 50 from the hook 30 may employ a heavy machine instead of the above gripping means. In that case, the heavy machine on the bank 1 needs to hold the weight 50 by its own arm and remove it from the hook 30. After the water injection into the inner space 25 is completed, the manhole tube 8 connected to the manhole 28 is sequentially removed as in the first embodiment, and the dome body 10 in the temporary closing structure 100 is also lifted by the crane 80 and removed. The process is complete.

  The attachment and removal of the weight 50 may be performed by cooperation of underwater work by a heavy machine and a diver. Further, the weight 50 attached to the outside of the dome body may be a ring in which arc-shaped members are combined so as to be foldable so as to fit in a headband shape on the outer periphery of the dome body 10.

  In either of the first and second embodiments, the weight is continuously charged or held while draining from the inner space, or the weight is continuously poured while water is poured into the inner space. The form of discharging or removing was illustrated, but the drainage work from the interior is temporarily stopped for each predetermined amount of drainage, and the weight is inserted and held according to the buoyancy at that time, and similarly the water injection work to the interior is performed. It is good also as stopping once for every predetermined water injection quantity, and discharging | emitting or removing a weight according to the buoyancy in that case.

  Thus, according to each embodiment mentioned above, the provisional deadline structure which can cope with the buoyancy which acts with internal drainage work at the time of construction can be provided.

  Although the embodiment of the present invention has been specifically described based on the embodiment, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Dam body 2 Through-hole 3 Dam dam body upstream surface 4 Opening 4a Through-hole planned opening position 5 Ground 6 Water level gauge 7 Water stop material 8 Manhole pipe 9 Fall prevention material 10 Dome body (temporary closing structure)
21 Opening 22 Weight inlet 23 Weight outlet 24 Outer peripheral surface 25 Inner air 27 Air supply valve 28 Manhole 29 Drain valve 30 Hook 31 Input pipe (weight input path)
32 Weight transfer means 33 Skirt portion 35 Partition plate 45 Air pipe 46 Bell mouth 47 Closed door door door 48 Discharge pipe 49 Closed gate door body 50 Weight 51 Ring 60 Weight supply device 70 Temporary structure

Claims (5)

It is a construction method of a temporary closing structure used when constructing a through-hole in an existing dam body.
A step of watertightly contacting the opening of the dome body, which is a temporary closing structure, at the planned opening position of the through hole on the upstream surface of the dam dam body;
While draining the water in the inner space of the dome body, and sequentially throwing weights into the inner space;
The construction method of the temporary cutoff structure in the dam dam body characterized by including. In claim 1,
A method for constructing a temporary closing structure in a dam dam body, comprising a step of sequentially discharging weights from the inner space while pouring water into the inner space of the dome body when removing the temporary closing structure. It is a construction method of a temporary closing structure used when constructing a through-hole in an existing dam body.
A step of watertightly contacting the opening of the dome body, which is a temporary closing structure, at the planned opening position of the through hole on the upstream surface of the dam dam body;
A step of sequentially holding weights on the outside of the dome body while draining water in the inner space of the dome body;
The construction method of the temporary cutoff structure in the dam dam body characterized by including. In claim 3,
A method for constructing a temporary closing structure in a dam dam body, comprising a step of sequentially removing weights from the outside of the dome body while water is poured into the inner space of the dome body when removing the temporary closing structure. In any one of Claims 1-4,
In order to balance the total weight of the weight and the dome body at a certain point in time with the buoyancy generated in the dome body, the weight is sequentially inserted into the inner space or sequentially held outside the dome body, or A construction method for a temporary closing structure in a dam dam body, wherein the weights are sequentially discharged from the inner space or sequentially removed from the outside of the dome body.

Images