JP2005139865A - Underwater temporary cofferdam installation and its construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To install a bottom block having a large weight without using a large-sized heavy machinery. <P>SOLUTION: The underwater temporary cofferdam installation is provided at least with a caisson 22 installed on a concrete face 2a of a water reservoir side of a dam weir body 2, a watertight hardware 9 arranged at the foot of the caisson 22 and the bottom block 21 placed under the caisson 22 to support a buoyancy which acts on the caisson 22 when discharging water. The bottom block 21 is constructed in such a way that underwater concrete 21b is filled into a steel formwork 21a secured by a chemical anchor and that transmission of the temporary cofferdam tare acted on the bottom block 21 and of the buoyancy load acted when draining water in the temporary cofferdam are executed by an insertion reinforcing bar connecting the bottom block 21 and the dam weir body 2. Since the bottom block having a large weight can be easily installed without using the large-sized heavy machinery, the buoyancy generated when water is discharged within the caisson becomes smaller and the load affecting the dam weir body through the anchor is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an underwater provisional cutoff facility attached to a dam weir body and a method of constructing this underwater provisional cutoff facility in order to separate a dam weir body and a reservoir, for example, when improving a dam facility.

  For example, when improving a dam facility, prior to the construction, an underwater temporary cutoff facility is temporarily attached to the concrete surface of the dam weir on the reservoir side to separate the construction part and the reservoir in the dam weir. Hereinafter, a conventional underwater temporary cutoff facility will be described with reference to FIGS. 3 and 4.

  3 and 4, reference numeral 1 denotes a caisson, which is a box-type structure attached to the concrete surface 2 a on the reservoir side of the dam weir body 2 in order to secure some work space. The caisson 1 has a “U” -shaped ramen structure in a plan view, and is horizontally divided into a plurality of blocks and carried in the height direction.

  The caisson 1 is installed on the bottom lid 3 previously installed on the concrete surface 2a, and is integrated with the bottom lid 3, the movable lid 4 attached to the upper surface of the uppermost block of the caisson 1, and the door stop of the concrete surface 2a. The watertight metal fitting 9 keeps the watertight and secures the work space inside. The hydraulic load acting on the caisson 1 is transmitted to the concrete surface 2a via the leg portion 1a having a rigid frame structure.

  5 is installed on the upstream surface of the dam weir body 2, and is the total weight of the equipment (the downward force obtained by adding up the total weight of the movable lid 4, the caisson 1, the bottom lid 3, the lifting prevention material 7 described later, and the hanging hardware 8; It is a support frame that supports buoyancy acting on the caisson 1, and transmits the self-weight and buoyancy to the concrete surface 2 a via the PC anchor 6.

  7 is an anti-lifting material inserted between the uppermost block of the caisson 1 and the support frame 5 after the caisson 1 is installed and before the caisson 1 is drained. The buoyancy is transmitted to the support frame 5 as a compression force.

  Reference numeral 8 denotes a hanging metal object for connecting the support frame 5 and the bottom lid 3, and the weight of the bottom lid 3 and the weight acting on the bottom lid 3 (the weight of the caisson 1, the movable lid 4, and the lifting prevention material 7). ) Is transmitted to the support frame 5 as a tensile force.

  The above-described bottom lid 3 has a partial tank structure in order to reduce drowning during towing, and is a structure positioned above the bottom lid 3 after being connected to the support frame 5 via the hanging hardware 8. On the other hand, the water pressure (buoyancy) acting on the bottom surface is transmitted to the caisson 1 when draining inside the caisson 1. The movable lid 4 is attached to the upper surface of the uppermost block of the caisson 1, and prevents water from entering the caisson 1 when the water level rises above the top of the caisson 1. Moreover, although it is always open (during work), it is closed in advance if there is a possibility that the water level of the reservoir will rise.

  In addition, the said watertight metal fitting 9 is comprised from the bearing surface and the watertight surface, and has a structure which can transmit the water pressure of the caisson 1 reliably. Further, reference numeral 10 in FIGS. 3 and 4 denotes a tightening metal that connects the caisson 1 and the dam weir body 2 as an earthquake countermeasure.

  However, in the conventional underwater temporary cutoff facility, each block constituting the caisson 1 moves due to buoyancy generated during drainage inside the caisson, which causes water leakage. In addition, if the water depth at the installation location is deep or the size of the equipment is increased, the lift prevention equipment that supports buoyancy becomes large, and if the caisson's own weight increases, the suspension equipment that supports it also becomes large. there were.

Therefore, as a solution to the problems in the conventional underwater provisional cutoff facility, the present applicant is installed on at least the concrete surface 2a on the reservoir side of the dam weir body 2 as shown in FIGS. The caisson 12, the movable lid 4 attached to the upper surface of the caisson 12, the watertight hardware 9 provided on the leg of the caisson 12, and the buoyancy that is disposed at the lower part of the caisson 12 and acts on the caisson 12 during drainage The bottom block 11 has, for example, a hydraulic anchor 11a pressed against the concrete surface 2a by water pressure, a support girder 11b for transmitting the buoyancy to the hydraulic anchor 11a, and a caisson 12 Water in which a lower open type air chamber 12aa is provided in at least one of the blocks 12a and the bottom block 11 constituting the water. It has proposed a provisional deadline equipment.
JP 11-229355 A

  This underwater temporary closing facility proposed by the present applicant is necessary for the conventional underwater temporary closing facility, and the buoyancy generated when draining the caisson support frame and hanging hardware to support the caisson's own weight. It is possible to omit the anti-lifting material that supports the water and to reduce water leakage caused by the movement of the block due to buoyancy when the caisson is drained.

  However, the underwater provisional cutoff system proposed by the present applicant is a steel structure with a bottom block composed of a support girder and a hydraulic anchor, and its own weight is small, so the buoyancy increases and acts on the dam weir body via the hydraulic anchor. The burden to do was increasing. In order to reduce the load of the hydraulic anchor, the weight of the bottom block may be increased. However, when the weight of the bottom block is increased, a large heavy machine is required for installing the bottom block. However, there were cases where large heavy machinery could not be used due to the structure of the dam weir body.

  The problem to be solved by the present invention is that a bottom block having a large weight cannot be installed without using a large heavy machine.

The underwater provisional cutoff facility of the present invention is
At least a caisson installed on the concrete surface of the reservoir side of the dam weir body, a watertight hardware provided on the leg of the caisson, and a bottom part disposed under the caisson and supporting the buoyancy acting on the caisson during drainage In the underwater provisional cutoff facility with blocks,
The bottom block is a structure in which underwater concrete is filled in a steel mold, and the temporary blockage dead weight acting on the bottom block and buoyancy load transmission acting at the time of draining in the temporary cutout are transmitted to the bottom block and the dam weir body. The main feature is that it is performed by an insertion line connecting the two.

Moreover, the construction method of the underwater provisional cutoff facility of the present invention is as follows:
After fixing the steel formwork in place on the concrete surface at the reservoir side of the dam weir body with an anchor, the bottom block is formed by pouring underwater concrete into this steel formwork,
The most important feature is the installation of the caisson on the bottom block.

  According to the present invention, since the underwater concrete is poured into the steel mold after sinking the relatively light steel mold, it is easy to install a bottom block having a large weight without using a large heavy machine. can do. And by adopting a bottom block with a large weight, the buoyancy generated when draining the inside of the caisson is reduced, and the load acting on the dam weir body via the anchor is reduced.

  Hereinafter, an example of the underwater provisional cutoff facility according to the present invention will be described with reference to FIGS. 1 and 2. 1 and 2, the same reference numerals as those in FIGS. 3 to 6 denote the same or corresponding parts, and a detailed description thereof will be omitted.

  1 and 2, reference numeral 21 denotes a bottom block. For example, a lower support girder 21c and a mold 21a made of steel, an underwater concrete 21b filled in the mold 21a, a submerged concrete 21b and a dam. It is formed by an insertion line 21d that joins the weir body 2. In the underwater provisional cutoff facility of the present invention, the lower support girder 21c and the mold 21a are fixed to predetermined positions on the concrete surface 2a on the reservoir side of the dam weir body 2 with chemical anchors or the like. Then, after constructing the necessary number of insertion bars 21d, the underwater concrete 21b is poured into the mold 21a fixed with this chemical anchor or the like to be cured. This completes the installation of the bottom block 21 to the dam weir body 2.

  And in this invention, after fixing the formwork 21a to the predetermined position of the dam weir body 2 with a chemical anchor etc. as mentioned above, and inserting the reinforcement | strut 21d in the dam weir body 2 in the formwork 21a, underwater concrete 21b The caisson 22 is placed on the bottom block 21 filled with the. The caisson 22 has a “U” -shaped structure in a plane and is the same as the conventional caisson in that it is horizontally divided into a plurality of blocks in the height direction. A circular or polygonal structure may be used. Then, the movable lid 4 may be installed on the upper surface of the uppermost block of the caisson 22, and the work space inside the caisson 22 is kept watertight by the watertight hardware 9 integrated with the door stop of the concrete surface 2a. It is the same. The watertight hardware 9 may be installed before or after the bottom block 21 is installed.

  After the caisson 22 is installed, the buoyancy acting on the bottom block 21 is transmitted to the dam weir body 2 by shearing of the insertion bar 21d and concrete bearing pressure.

  As described above, the underwater provisional shut-off facility according to the present invention has the insertion weight 21d for integrally joining the underwater concrete 21b and the dam weir body 2 filled in the bottom block 21 with its own weight and buoyancy acting on the bottom block 21. By adopting a structure that transmits to the dam weir body 2 by the support pressure of the concrete, the transmission position of the load (self-weight and buoyancy of the caisson 22) to the dam weir body 2 is compared with the conventional underwater temporary cutoff facility. Since it can be made below 2, the burden on the dam weir body 2 can be greatly reduced.

  Further, since no structure is required above the caisson 22, the equipment weight can be reduced and the equipment structure can be simplified.

  The present invention is not limited to the above-described embodiment, and modifications of the embodiments are arbitrarily made within the scope of the technical idea of the present invention, such as one in which a formwork and a lower support girder may be integrally formed. is there.

  As described above, the present invention is not limited to the provisional deadline in a dam facility, but can also be applied to a provisional deadline for a building constructed in water.

It is a front view of the underwater temporary cutoff equipment concerning the present invention. It is a side view of FIG. It is a front view of the conventional underwater temporary cutoff equipment. FIG. 4 is a side view of FIG. 3. (A) is a schematic side view of the underwater temporary cutoff facility disclosed by patent document 1, (b) is a front view of (a). It is a detailed view of a caisson block constituting the underwater provisional cutoff facility disclosed in Patent Document 1, wherein (a) is a front view, (b) is a BB view of (a), and (c) is (b). FIG.

Explanation of symbols

2 Dam body 2a Concrete surface 9 Watertight hardware 21 Bottom block 21a Formwork 21b Underwater concrete 21d Inserting bar 22 Caisson

Claims (2)

A caisson installed at least on the concrete surface of the reservoir side of the dam weir,
Watertight hardware provided on the legs of this caisson,
In the underwater provisional cutoff facility provided at the bottom of the caisson and having a bottom block that supports buoyancy acting on the caisson during drainage,
The bottom block is a structure in which underwater concrete is filled in a steel mold, and the temporary blockage dead weight acting on the bottom block and buoyancy load transmission acting at the time of draining in the temporary cutout are transmitted to the bottom block and the dam weir body. An underwater temporary cut-off facility characterized in that it is performed by an insertion line that connects the two. It is a construction method of the underwater temporary cutoff facility according to claim 1,
After fixing the steel formwork in place on the concrete surface at the reservoir side of the dam weir body with an anchor, the bottom block is formed by pouring underwater concrete into this steel formwork,
Next, a construction method for an underwater temporary cutoff facility characterized in that a caisson is installed on the bottom block.

Images