JP3771816B2 - Method for forming openings in sabo dams - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an opening in a sabo dam, and more particularly, to a method for forming an opening without adversely affecting the periphery when soil is accumulated inside an existing sabo dam.
[0002]
[Prior art]
The original purpose of the sabo dam is to prevent sediment runoff due to sudden flooding such as flash floods, and to protect the river basin along the debris flow disaster.
[0003]
Recently, however, the importance of sabo dams has declined due to the development of revetments, etc., and sediments accumulated in the upstream of the dam cannot function freely as sabo dams, or deposits of sludge humus In some cases, such as downstream water pollution or pollution caused by sewage, its presence may adversely affect the environment.
[0004]
On the other hand, rivers tend to be reviewed as a resource for breeding freshwater fish recently. However, if the existing sabo dam is left untouched as described above, it will become an obstacle to the migration of migratory freshwater fish.
[0005]
Therefore, for the promotion of river basin fisheries and the accompanying increase in catch production and for fish farm facilities constructed upstream, opening of fishway openings in existing sabo dams will enable freshwater fish to run up. Measures have come to be taken.
[0006]
However, when forming an opening for a fishway with earth and sand accumulating on an existing sabo dam, there are problems described below.
[0007]
[Problems to be solved by the invention]
That is, in the existing sabo dam, if the opening is formed with the sediment deposited on the upstream side as it is, not only does a large amount of sediment sediment flow to the downstream side, causing turbid water, The fishery resources such as salmon and carp in the downstream area will be greatly affected, and fishery compensation problems will occur due to the drastic decrease in catch.
The present invention has been made to solve such a problem, and the object of the present invention is to form a necessary opening while avoiding the outflow of the sediment accumulated in the sabo dam to the downstream side. It is providing the formation method of the opening part in a sabo dam.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a first step of dredging sediment deposited on the upstream side of an existing sabo dam, and a dam dam body of the sabo dam by a cutting means such as a wire saw to deposit sediment after the dredging. A second step in which a rectangular cutting block is formed by cutting to a depth reaching a position above the surface; and the rectangular cutting block is jacked up, and the dam dam body is penetrated under the rectangular cutting block. A third step of providing a drain opening to discharge water from the drain opening to lower the water level in the sabo dam, removing the rectangular cutting block, and partially opening the dam dam body A fourth step of forming a section, and by sequentially repeating the first to fourth steps, an opening having a predetermined length is formed in the dam dam body.
[0009]
According to the method of forming an opening according to the present invention configured as described above, after dredging earth and sand, water is discharged from the drain opening on the upper side, and further, dredging and discharging are repeated. Since the opening of a predetermined length is formed in the dam body by extending the partial opening downward, the necessary opening while avoiding the outflow of earth and sand accumulated in the sabo dam to the downstream side The part can be formed.
[0010]
In the case of the present invention, the rectangular cutting block is divided into two blocks of a tapered taper block and an inverse taper block by an oblique dividing line, and these blocks can be jacked up alternately.
[0011]
According to this configuration, it is possible to smoothly jack up while avoiding the competition of the rectangular cutting blocks.
[0012]
Further, in the case of the present invention, a pair of guide holes straddling each other between the dam dam body and the rectangular block are formed in a substantially vertical direction of the dam dam body, and the block is jacked up. A guide rod for guide can be inserted into each guide hole.
[0013]
According to this configuration, the block can be jacked up smoothly against the pressure of the water flow.
[0014]
Furthermore, in the case of the present invention, the opening is provided at three or more locations at a predetermined interval in the dam dam body, and after the partial opening is formed at two locations on one side, the remaining one or more locations are provided. Temporarily cut off the peripheral edge of the predetermined position of the opening, and while discharging water from the drain opening formed below the partial opening, the formation planned position of the remaining one or more openings is made dry. An opening having a predetermined length can be formed without providing the partial opening at a position where the opening is to be formed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1-8 has shown one Example of the formation method of the opening part in the sabo dam concerning this invention.
[0016]
The formation method of the opening part shown in these figures is a case where this invention is applied when forming the opening part for fishway in the existing sabo dam, and each figure is a front view and its AA in each figure. The cross section in a line and a BB line is shown.
[0017]
The method of forming the opening of this example is as follows:
(1). A first step of dredging sediment 5 deposited on the upstream side of the existing sabo dam 1;
(2). A second step of forming a rectangular cutting block B by cutting the dam body of the sabo dam 1 to a depth reaching a position above the surface of the sediment earth 5 after dredging by cutting means such as a wire saw;
(3). The rectangular cutting block B is jacked up, and a drain opening O penetrating the dam dam body 1 is provided at the lower part of the rectangular cutting block B], and water is discharged from the drain opening O to prevent sabo. A third step of lowering the water level in the dam 1,
(4) including a fourth step of removing the rectangular cutting block B and forming the partial opening S1 in the dam body 1;
(5). By repeating these first to fourth steps sequentially, the basic configuration is to form the opening S having a predetermined length in the dam dam body 1 by sequentially extending the partial opening S1 downward.
[0018]
As shown in FIG. 1, the existing sabo dam which is intended to form the opening S in this embodiment is a concrete dam in which a dam body of the sabo dam 1 is provided with a recess in the center, and a lower center portion thereof. Slightly large drainage holes 2 and small drainage holes 3 and 4 are formed in the left and right and top and bottom of the drainage holes 2, and each drainage hole 2 to 4 is closed by a corner-dropping gate or the like. ing.
[0019]
In the figure, symbol (R) indicates the right bank and (L) indicates the left bank. Moreover, the part shown with a broken line shows the formation planned location of the opening part S for fishways, and these opening parts S pass through the formation position of each drain hole 2, 3, and 4 so that it may reach below it. And a total of three locations.
[0020]
The state before construction of the existing sabo dam 1 will be described. On the upstream side of the dam 1, the earth and sand 5 approximately the height of the dam 1 is deposited, and the water surface WL is slightly higher than the central portion of the dam 1. The levee body 1 overflows and is discharged downstream.
[0021]
In this state, first, the drainage holes 2, 3 and 4 are closed, and the sediment 5 accumulated on the upstream side is removed to a predetermined depth position by a clamshell or the like (first step). .
[0022]
At this time, on the left bank side, crawling up to the vicinity of the dam 1 and then applying the embankment 6 on the sedimentary sand 5 upstream of the left bank to secure a scaffold, and then crawler crane that combines material lifting and dredging work etc. 7 is installed on the upper side of the embankment 6.
[0023]
Next, as shown in FIG. 2, a prefabricated work platform 8 is installed by being lifted by a crane 7 above the planned slit formation position on the center and left bank (L) side.
[0024]
At this time, the upper drain hole 3 on the left bank (L) side is closed with an iron plate or the like. Further, a plurality of bracket scaffolds 9 are temporarily installed on the left bank side. Next, the wire saw driving device 10 is installed on the work platform 8.
[0025]
Then, as shown in FIG. 3, after opening a wire through hole penetrating the dam 1 almost horizontally at the slit formation scheduled position, the wire saw W is hung between the through hole and the wire saw driving device 10 and guided. The left and right sides and the center are cut vertically and the bottom is cut horizontally to form a rectangular cutting block B (second step). The cutting depth at this time is set at a position where underwater cutting is possible slightly above the ground surface EL of the laid sedimentary sand 5.
[0026]
In parallel with this operation, eight anchor steel bars 11 for jacking up the cutting block B are prepared for each block, and these anchoring steel bars 11 are inserted and fixed to the rectangular cutting blocks B, respectively. To do.
[0027]
Next, as shown in FIG. 4, the jack 12 connected to the anchor steel bar 11 is arranged on the work platform 8, and the cutting block B is jacked up, so that the water level lowering portion is formed below the rectangular cutting block B. The water drain opening O is opened, the water in the dam 1 is discharged from the water drain opening O, and the back water level in the dam 1 is gradually lowered (third step).
[0028]
In this case, if the cross-sectional area of the drainage opening O is increased, and if it is opened at once, dirt and sand will be entrained at the time of discharge and turbid water will be generated. Discharge while adjusting the amount.
[0029]
The cutting shape of the rectangular cutting block B and the detailed procedure for jacking up will be described later. If the rectangular cutting block B is pulled up and held as it is, and the water level of the dam 1 is lowered, as shown in FIG. The gates of the drain holes 2 and 4 are opened, and the water level WL is further lowered.
[0030]
In the case of the present embodiment, since the drain hole 2 exists, such a treatment can be performed. However, when there is no drain hole 2, this step is not necessary. Thus, when the water level in the dam 1 falls, the sandbag 15 is piled on the slope of the dredged earth and sand 5 and the outflow is blocked | prevented.
[0031]
Thereafter, the rectangular cutting block B is jacked down, further cut and subdivided, and then lifted and removed sequentially by the crane 6 to form a partial opening S1 on the center and left bank (L) side as shown in FIG. Is done. In this case, the rectangular cutting block B can be removed by jacking up as it is without jacking down (fourth step).
Further, in parallel with this work, the right bank (R) is beaten, and after the dredging is completed, a dry work is performed, and a cutting work using the wire saw W similar to the above is sequentially performed. Without forming the rectangular cut block, a rectangular cutting block having a predetermined length is formed at a time, and the opening S having a predetermined length is completed by removing the rectangular cutting block.
[0032]
Next, as shown in FIG. 7, the right bank (R) temporary cut-off is removed, the sand bank 15 is loaded on the left bank (L), and the temporary cut-off is performed. Then, the remaining portion is sequentially cut and removed by the same operation procedure as described above to complete the full-length opening S.
[0033]
Finally, as shown in FIG. 8, the center is temporarily cut off with a sandbag 15 and water is allowed to flow from the left and right openings S, and the remaining part is continuously provided below the partial opening S1 of the central part by a dry operation. Are sequentially cut and removed by the same operation procedure as described above to complete the full length opening S.
[0034]
FIG. 9 shows the completed state of the sabo dam 1 described above. The drop between the upstream and downstream water levels WL of the dam 1 is extremely low depending on the bottom surface height of the opening S, and the fish runs up and down. The height will not hinder. In the figure, the bottom surface of the opening S has an inclined slope toward the downstream side. However, a stepped step may be provided at the stage of finishing the bottom surface of each opening S.
[0035]
Next, the cutting shape of the rectangular cutting block B and the detailed jack-up procedure of the rectangular cutting block B will be described with reference to FIG.
[0036]
FIG. 10A shows a top view and a side view of the rectangular cutting block B in a state where the cutting with the wire saw W has been completed. In this embodiment, the rectangular cutting block B is divided into left and right cutting blocks B1 and B2.
[0037]
A through hole SH of the wire saw W penetrates the dam body 1 in advance at the intersection of the vertical cutting line L1 and the horizontal cutting line L2 and the intersection of the central dividing line L3 and the horizontal cutting line L2 of each block B1, B2. So that it is drilled.
[0038]
The dividing line L3 is not vertical but is formed obliquely, whereby the left block B1 has a tapered shape and the right block B2 has a reverse taper to ensure the ease of jack-up work after cutting.
[0039]
In addition, a pair of circular guide holes GH are formed substantially vertically so as to be positioned at the central part of the dam body thickness of the dam 1 at approximately the center position of the vertical cutting lines L1 on both sides.
[0040]
This guide hole GH is formed so as to straddle between the dam body of the dam 1 and the left and right blocks B1 and B2 of the rectangular cutting block B separated from the dam body by cutting lines L and L2. A guide rod 14 for guiding when jacking up is inserted.
[0041]
Four anchoring steel bars 11 for jacking up are embedded in four corners of each of the blocks B1 and B2. When jacking up such a rectangular cutting block B, the following procedure is performed.
[0042]
That is, first, as shown in FIG. 10B, the left block B <b> 1 having a tapered shape is pulled upward by an unillustrated jack through the anchor steel rod 11. And if this left side block B1 is pulled up to some extent, it will hold | maintain in this position.
[0043]
In this state, as shown in FIG. 10C, the right block B <b> 2 can be pulled up, and this time, the right block B <b> 2 is pulled upward by the jack (not shown) via the anchor steel bar 11.
[0044]
At this time, the right block B1 is pulled up to the same position as the left block B1 and held at that position. By repeatedly performing such alternate jack-up operation, both the blocks B1 and B2 can be pulled up, and a predetermined drainage opening O for discharge can be formed in the lower part thereof.
[0045]
In this embodiment, the rectangular cutting block B is divided into a tapered taper shape and a reverse taper shape by an oblique dividing line L3 for the following reason. That is, if the cutting lines L and L2 are formed by a wire saw and are to be pulled upward while remaining rectangular, the cutting lines L and L2 formed by the wire saw W have a width of about a dozen mm, It is relatively small, and as the cutting progresses, its width becomes narrower, and furthermore, it is difficult to form accurately perpendicularly due to cutting resistance etc., so when pulling up, the cutting surface competes, The raising becomes very difficult and almost impossible.
[0046]
However, when the rectangular cutting block B is divided into a taper taper shape and an inverse taper shape by an oblique dividing line L3, the taper taper block B1 is pulled up first, and then the jack-up operation is repeated alternately to block B1. , B2 can be lifted smoothly without such competition.
[0047]
In this case, since the guide rod 14 is inserted into each guide hole GH formed so as to straddle between the left and right blocks B1 and B2, the blocks B1 and B2 can be smoothly jacked up.
[0048]
Further, when the rectangular cutting block B is pulled upward, water in the dam 1 tends to flow downstream, and the water pressure associated therewith acts. In this case, between the left and right blocks B1 and B2 Since the guide rod 14 is inserted into each guide hole GH formed so as to straddle the block, each block B1, B2 can be held in a predetermined position and state against this water pressure. As a result, the pulling operation can be easily performed.
[0049]
In the above embodiment, the wire saw W is exemplified as the cutting means for forming the rectangular cutting block B. However, the embodiment of the present invention is not limited to this, and for example, a disk-shaped blade is used. Cutting means may be used, or cutting means using these in combination.
[0050]
Further, in the above embodiment, the case where the opening S having a predetermined length is formed by repeating the process twice, but the implementation of the present invention is not limited to this and the number of times more than this. May be repeated.
[0051]
【The invention's effect】
As described above, according to the method of the present invention, the fishway opening can be formed while preventing the sediment sediment from flowing out to the downstream side, so that the downstream impact due to the sediment outflow can be prevented.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a first step of a method of the present invention.
FIG. 2 is an explanatory diagram showing a next step subsequent to FIG.
FIG. 3 is an explanatory view showing the same process.
FIG. 4 is an explanatory view showing the same process.
FIG. 5 is an explanatory view showing the same process.
FIG. 6 is an explanatory view showing the same process.
FIG. 7 is an explanatory view showing the same process.
FIG. 8 is an explanatory diagram showing the final step.
FIG. 9 is a perspective view showing a construction completion state.
FIGS. 10A to 10C are explanatory views showing a cutting shape of a cutting block and a pulling-up procedure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sabo dam 5 Accumulated sediment 7 Crawler crane WL Water surface 8 Work stand 10 Wire saw drive device 12 Jack W Wire saw S1 Partial opening S Opening B Rectangular cutting block B1, B2 Cutting block

Claims (4)

A first step of dredging sediment deposited on the upstream side of an existing sabo dam;
A second step of forming a rectangular cutting block by cutting the dam body of the sabo dam to a depth reaching a position above the surface of the sediment after the dredging by cutting means such as a wire saw;
Jack up the rectangular cutting block, and provide a drain opening through the dam dam body at the lower part of the rectangular cutting block, to discharge water from the drain opening, and in the sabo dam A third step of lowering the water level;
A fourth step of removing the rectangular cutting block and forming a partial opening in the dam dam body,
A method of forming an opening in a sabo dam, wherein an opening having a predetermined length is formed in the dam dam body by sequentially repeating the first to fourth steps. 2. The rectangular cutting block is divided into two blocks of a tapered taper block and a reverse taper block by oblique dividing lines, and these blocks are alternately jacked up. Of forming the opening of the substrate. A pair of guide holes straddling each other between the dam levee body and the rectangular block are drilled in a substantially vertical direction of the dam dam body, and a guide rod for guiding when jacking up the block, The method for forming an opening according to claim 2, wherein the opening is inserted into each guide hole. The opening is provided at three or more locations at a predetermined interval in the dam dam body,
After forming the partial opening at two locations on one side, temporarily cut off the periphery of the planned position of the remaining one or more openings,
While discharging water from the drain opening formed below the partial opening, the formation position of the remaining one or more openings is in a dry state,
2. The method for forming an opening in a sabo dam according to claim 1, wherein the opening having a predetermined length is formed at a place where the opening is to be formed without providing the partial opening.

Images