JP4047030B2 - Transmission type sabo dam - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission-type sabo dam that supports debris flow, in which fine-grained sediment during a normal period flows down through an opening provided in a levee body, and the opening is closed and stored with a large-grained soil during flooding.
[0002]
[Prior art]
As is well known, many sabo dams have been installed in the past to prevent devastation in mountainous areas due to a sudden outflow of sediment and deterioration of water storage function due to sedimentation, and in addition to rainy seasons, typhoons, etc. It is a place that should be installed immediately to protect private houses, facilities, roads, etc. from damage from debris flow caused by torrential rain.
[0003]
Conventionally, as a sabo dam, a concrete gravity sabo dam 50 as shown in FIG. 11 has been generally constructed. Most of the concrete gravity sabo dam 50 made of concrete is a so-called impervious type that dams even small gravel and muddy water and completely stores earth and sand.
[0004]
Such an impervious sabo dam has a sense of security to completely store sediment, but on the other hand, it has a major disadvantage that it tends to impair the function of the sabo dam as sediment accumulates at normal times and the preparation capacity decreases. have. In recent years, it has been clearly clarified that natural sediment transport downstream is necessary to prevent river and coastal erosion, and that continuity of upstream and downstream water systems is necessary for ecosystems such as fish. It has been.
[0005]
For this reason, a permeable sabo dam has been proposed, in which the opening is blocked by the engagement of gravel during the flow of debris, and small gravel and muddy water in the normal state pass downstream. As these general forms, a dam 60 having a slit S and made of concrete as shown in FIG. 12 and steel pipes 71 shown in FIG. 13 as shown in Japanese Patent Publication No. 58-51568 are arranged in a three-dimensional grid. There are steel pipe transmission type dams 70, etc., and each has a very large number of construction results.
[0006]
[Problems to be solved by the invention]
In the case of a concrete dam 60 having slits as shown in FIG. 12, there are the following problems.
[0007]
(1) Since the concrete dam 60 having a slit has a low tensile strength of the material, the wall body 61 cannot be made thin in order to resist a huge external force acting on the dam.
[0008]
(2) According to the document “Experiment on Debris Flow Countermeasure Sabo Facility” in “Civil Engineering Technical Data 22-2” (1980), if the slit net interval is not less than 1.5 times the maximum gravel diameter d _{95 in} the flowing sediment, It is said that the debris flow cannot be blocked at the time of debris flow, and eventually there is a limit to taking a large permeable part. For this reason, there is a concern that sand gravel tends to be stored during normal times, and the sand storage capacity is reduced during debris flow.
[0009]
(3) In addition, in a stream with a large flow rate, the water level is likely to rise due to dam raising. There is a risk of re-flow of gravel. An increase in water pressure due to rising water level also causes the cross section to be enlarged.
[0010]
(4) The concrete corners 61a and 61b, which are structural weak points, are chipped due to the impact of gravel, etc., and the cross section decreases, or the gravel enters between the slits and the side wall surface is shaved and the thickness decreases, There are concerns about structurally compromised safety.
[0011]
(5) Furthermore, it is an important problem from the viewpoint of maintaining the function of the dam that gravel stopped between the slits is extremely difficult to remove from the narrowness of the slits.
[0012]
Japanese Patent Application Laid-Open No. 11-50435 invents a concrete dam with a beam material provided on the upstream surface between slits as shown in FIG. In this dam 80, cross beams 81 extending in the left-right direction of the slit S are arranged in a multi-stage on the upstream surface of the dam, and each cross beam 81 is fixed to the base material 82. It has been resolved.
[0013]
However, (1) When considering stability against sedimentation pressure, pressure is also applied to the cross beam between the slits due to blockage, so increasing the net clearance between the slits reduces the weight of the dam in the same section. (2) It is difficult to replace when the horizontal beam is dented due to the impact of a boulder because the horizontal beam is upstream of the dam. (3) As shown in FIG. There remains a problem to be solved, such as the concern that the bottom plate 83 may be damaged by the fall of overflowing gravel.
[0014]
The steel pipe transmission type dam 70 as shown in FIG. 13 has the advantage that the transmission part can be enlarged by taking advantage of the strength of the steel material, and the sand storage capacity is ensured at the time of debris flow because it is difficult to store the gravel normally. In addition, since the water level is not easily raised due to the dam upstream of the dam, there is an advantage that the engagement of the soil particles at the tip of the debris flow is not loosened and the clogging between the slits is surely ensured.
[0015]
However, on the other hand, it is expensive compared to concrete because of its high material and high degree of processing, and it is very difficult to replace due to its complicated connection when it is dented by the impact of boulders. Have the disadvantages. In addition, it is common to stop gravel at the interval of the most upstream member. In this case, the problems (2) and (3) are the same as those of the concrete dam 80 in which a beam is provided between the slits. In addition, the gravel deposited inside the lattice of the steel pipe 71 as shown in FIG. 16 has a drawback that it is difficult to remove stones.
[0016]
The present invention has the problems of the conventional concrete dam with slits as described above, the concrete dam with a beam material on the upstream surface between the slits, and the transmission type dam with steel pipes assembled in a three-dimensional grid. In the transmission type sabo dam that can secure sand storage capacity during debris flow by providing beam material at the opening, the cross section of the wall body and beam material can be reduced, and stability is improved. The purpose is to provide a transmission type sabo dam.
[0017]
[Means for Solving the Problems]
The present invention has a cross section in which a plurality of beam members are inclined in the direction of the river axis at a predetermined interval in the vertical direction on the downstream side of an opening having a predetermined width between the walls constituting the dam body. By arranging it, the width of the opening (transmission part) is increased, debris at the time of debris flow is dared to enter between the walls and stopped by the beam material, and sediment is deposited in the space upstream of the opening In addition, it is intended to solve the above-mentioned problems of the prior art by making the sediment accumulation shape a gentle gradient.
[0018]
That is, in the first aspect of the present invention , the beam material is stretched between the walls of the opening having a predetermined width formed between the walls, and the beam is vertically moved downstream of the opening. A plurality of walls arranged at predetermined intervals in the direction and inclined so as to be positioned on the upstream side in the vertical direction, and both ends of the beam member are opposed to each other with the opening therebetween A transmission type sabo dam, which is inserted into each side surface and configured to allow sand and gravel to enter and accumulate in a space surrounded by the side surface of the wall on the upstream side of the beam member.
[0019]
In this first aspect, the wall body is a normal bank body extending in a direction perpendicular to the river axis, or an independent structure (see FIG. 1) disposed at intervals in the direction perpendicular to the river axis. An opening is provided in the water passage portion of the levee body, or an independent structure is disposed with the opening. The independent structure has a horizontal cross section that is long in the direction of the river axis (direction of debris flow), and a concrete structure, a steel structure, a composite structure such as steel and concrete, or the like can be used. The plurality of beam members in the vertical direction are inclined with an upward slope toward the upstream side in a side view, and are aligned in a line at a constant inclination angle, or arranged in a single line (for example, in a side view) Bent, curved, etc.). In the case of a constant inclination angle, for example, a gradient of about 30 ° to 60 ° is preferable.
[0020]
The net spacing between walls should be at least twice the maximum gravel diameter in the debris flow.
[0021]
This is a case where the net interval between the walls is limited numerically so that the upstream side of the opening is not blocked during the debris flow. Falling up Tsubute径referred to in the present invention, in addition to the normal maximum gravel size, the category includes a stream up gravel diameter d ₉₅ (95% Tsubute径) or the like.
[0022]
Net spacing of beam members each other at most 1.5 times the falling up gravel size in debris flow.
[0023]
This is a case where the numerical values are limited so that the downstream side of the opening can be reliably closed during the debris flow. Also in this case, the maximum flow gravel diameter includes the maximum flow gravel diameter d _{95 in} addition to the normal maximum gravel diameter.
[0024]
Beam members has a joint as much as possible in the vicinity of the fixing portion of the wall, or the end is inserted into a hole provided in the wall, and is detachable from the wall.
[0025]
This is a case where it can be easily replaced when the beam material is damaged, and the end of the beam material is joined to the fixing portion of the wall body via a joint such as a flange joint, or Insert the end of the beam material into a hole made of a sheath tube or the like provided on the wall, or divide the beam material into an end portion and an intermediate portion to be inserted into the hole, and join the end portion and the intermediate portion to each other Join through. Further, Harizai is Keru set inside between walls. As the beam material, a steel member such as a steel pipe, a shape steel, a steel bar, or a wire, or a concrete member such as reinforced concrete or prestressed concrete can be used.
[0026]
Claim 2 of the present invention is the transmission type sabo dam according to claim 1 , wherein the wall body is provided with a bottom plate for fixing the wall body or a top plate for connecting the wall bodies.
[0027]
The second aspect of the present invention is a case where a wall plate is stiffened by providing a bottom plate or a top plate. As these bottom plate and top plate, steel members, reinforced concrete, unreinforced concrete, soil cement, a frame or a frame filled with gravel or the like can be used.
[0028]
Claim 3 of the present invention is characterized in that wall bodies and beam materials are alternately provided in the direction perpendicular to the river axis, or a plurality of sets of wall bodies and beam materials are provided at intervals. is a transmission Sabo dam according to any one of claim 1 or 2.
[0029]
This claim 3 is a case where a plurality of beam material openings are provided according to the width of the river to be constructed, and the wall body and the beam material are continuously provided in the direction perpendicular to the river axis, or the wall body and beam material unit. Are discretely arranged at intervals in the direction perpendicular to the river axis.
[0030]
(1) According to the transmission type sabo dam according to claim 1, as shown in FIG. 7, debris enters and accumulates between walls during debris flow, and the slope of sedimentation after debris flow stops is inclined Since it is approximated to the arrangement of the materials, the sediment pressure applied to the beam material between the wall bodies becomes smaller as the gradient becomes gentler, and the cross section of the wall body and the beam material can be made smaller.
[0031]
(2) In addition, as shown in Fig. 8, the shape of the sediment works as a counterweight against overturning in the direction of the river axis, so it also has an advantageous effect on the overall stability of the transmission-type sabo dam. Can be reduced.
[0032]
(3) be increased twice or more falling-up gravel size net spacing of the wall each other as not to block at the upstream end of the wall, entering the soil gravel into between the wall body is not inhibited. This is because, according to the above-mentioned document "Experiment related to debris flow countermeasure sabo facilities", if the slit net interval is more than twice the maximum gravel diameter in the flowing debris, the slit does not cause complete blockage. .
[0033]
(4) The debris flow will not flow downstream if the net spacing between beams is 1.5 times or less than the maximum gravel diameter in the debris flow so that the debris flow is closed and stopped. According to the above-mentioned document "Experiment related to debris flow prevention sabo facilities", it is said that if the slit pure interval is 1.5 times or less the maximum gravel diameter in the flowing debris, the slit will be completely blocked. It depends on.
[0034]
(5) If the damage to the beam members by dropping collision gravel by direct collision or fully sand after overflow of debris flow occurs, if detachable, it is easy to achieve functional recovery and replacement.
[0035]
(6) Furthermore, as shown in Fig. 9, gravel that overflowed after full sand is unlikely to increase in speed by falling so as to roll on a gentle slope, and is filled with sand at the time of falling collision. Because it is supported by sedimentary earth and sand, there is little risk of falling off beam materials.
[0036]
(7) Furthermore, when removing the beam material, the beam material is located on the downstream side between the walls, and since the slope of sedimentation is gentle, the risk of slope failure is small. Easy replacement of stones and beams.
[0037]
(8) According to the transmission type sabo dam according to claim 2 , it is possible to prevent a fall in a direction perpendicular to the river axis by providing a bottom plate or a top plate and connecting the wall bodies to each other.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a perspective view showing an example of a transmission type sabo dam according to the present invention. FIG. 2 is an exploded perspective view showing an example of a wall body of the transmission type sabo dam of FIG.
[0039]
As shown in FIG. 1, the transmission-type sabo dam 1 in this embodiment includes a wall body 2, a beam member 3, a bottom plate 4, and a top plate 5.
[0040]
(i) Wall 2
As shown in FIG. 1, the wall body 2 in the present embodiment is disposed at a predetermined interval in the direction perpendicular to the river axis, and an opening (transmission portion) 10 is formed therebetween. The pure interval W between the walls of the opening 10 is set to be twice or more the maximum falling gravel diameter in the debris flow. The shape of the wall body 2 is a semi-oval horizontal section, a trapezoidal shape in side view, and a long structure in the direction of the river axis (direction of debris flow). By arranging in such a manner, a sedimentation space 11 for earth and gravel is formed on the upstream side of the opening 10 (see FIG. 5). Further, the downstream side of the wall body 2 is an inclined surface 12 inclined at a gentle inclination angle θ ₁ .
[0041]
As shown in FIG. 2, the wall body 2 has a semi-oval horizontal cross section and a trapezoidal outer shell 2 a having a lateral view, a filling material 2 b, a semi-oval lid member 2 c, and a rectangular shape. The lid material 2d. After the inside shell 2a is filled with the filling material 2b, it is constructed by sealing it with the lid material 2c and the lid material 2d.
[0042]
The wall body 2 is a member that directly receives external forces such as impact impact force, debris flow fluid force, and sedimentation pressure, and also supports the fulcrum reaction force of the beam material 3, and is sufficient to resist these loads and not be destroyed. Strength is required. For this reason, in this embodiment, the outer shell 2a is made of a high-strength steel plate so as not to cause breakage due to the collision of the debris flow, to obtain a sealing property in which the filling material 2b does not leak as a mold, It is possible to prevent the wall body 2 from being scraped by gravel that has entered 10 and to disperse and propagate the collision impact force to the filling material 2b.
[0043]
The filling material 2b can resist an external force with its shear strength by being composed of soil cement which is stronger than soil and cheaper than concrete.
[0044]
The lid members 2c and 2d are made of concrete having high strength and high sealing performance, so that the soil cement of the filling material 2b can be prevented from being deteriorated by erosion or freezing and thawing.
[0045]
As shown in FIG. 3, the upstream side of the wall body 2 is semicircular in plan view, thereby eliminating a corner portion where stress concentration occurs and eliminating a structural defect. Moreover, it can be made to approach easily into the opening part 10 even with the maximum gravel diameter.
[0046]
Further, as shown in FIG. 4, the downstream side of the wall body 2 is grounded when it receives a load from the upstream side by being inclined at an inclination angle θ ₁ substantially parallel to the arrangement gradient of a beam member 3 to be described later. The dead load on the downstream side where the reaction force becomes high can be reduced, and the entire transmission type sabo dam 1 can be made difficult to fall.
[0047]
The dimensions such as the width and height of the wall body 2 are appropriately determined in consideration of the situation of debris flow at the installation site, external force conditions, workability, economy, and the like.
[0048]
(ii) Beam material 3
As shown in FIG. 1, the beam member 3 in the present embodiment is spanned between the pair of wall bodies 2 and 2 on the downstream side of the opening 10 in parallel with the direction perpendicular to the river axis and becomes vertically upward. Plural pieces are arranged so as to be inclined at an inclination angle θ ₂ and aligned in a row so as to be located on the upstream side. Inclination angle theta ₁ of the inclination angle theta ₂ between the inclined surface 7 of the beam member 3 is substantially equal to, relatively gentle angle of 45 °, for example, or the like. The mutual pure interval a of the beam members 3 is set to 1.5 times or less of the maximum gravel diameter in the debris flow. Accordingly, as shown in FIG. 5, to catch boulders in the beam member 3 can stop debris, and as shown in FIG. 7, the beam member 3 of the inclination angle theta ₂ to sedimentation gradient after debris flow stop Thus, the angle of repose can be made close to the angle of repose, and the sediment pressure on the beam 3 can be reduced.
[0049]
The beam member 3 is fixed to the side surface of the wall body 2, but is detachable from the wall body 2 so that the beam member 3 can be easily replaced when the beam member 3 is damaged. That is, as shown in FIG. 6, the beam member 3 is composed of a main pipe 3a, a sheath pipe 3b, and a joint portion 3c, and the main pipe 3a can be firmly fixed to the side surface of the wall body 2 and easily. It can be replaced.
[0050]
The main pipe 3a is a hollow circular steel pipe. Even if local deformation occurs, this member has a small reduction in cross-sectional rigidity, is a closed cross-section member, and has a low stress concentration. Therefore, safety is high even after debris and the like are stopped due to a collision with a debris flow.
[0051]
The sheath pipe 3b is a circular steel pipe whose inner diameter is slightly larger than the outer diameter of the main pipe 3a, is embedded and fixed in the wall body 2, and the end portion of the main pipe 3a is inserted therein. In order to minimize the member stress of the wall body 2 due to the fulcrum reaction force of the main pipe 3a, the length of insertion, that is, the length of the sheath pipe 3b is made sufficiently large to distribute the load. Further, the load between the end portion of the main pipe 3a and the sheath pipe 3b is transmitted through a cushioning material 13 such as rubber to reduce an impact load.
[0052]
The joint part 3c is for allowing the main pipe 3a longer than the pure interval W of the wall body 2 to be inserted into the sheath pipe 3b, and is a rib for detachably joining the central part and the end part of the main pipe 3a. There is no flange. The flange-less flange needs to be thicker than the rib, but the flange joint 3c has no impact buffer due to the dent. Ribs are not used to reduce the risk.
[0053]
When the gravel in the debris flow is large, the main pipe 3a can be a hollow steel pipe as in this embodiment to absorb the impact force by local deformation of the beam and reduce the load on the fulcrum, and the gravel is small Since the impact force is small, the beam material 3 can be selected as a steel pipe filled with mortar, concrete, or the like to reduce the dent.
[0054]
(iii) Bottom plate 4
The bottom plate 4 in the present embodiment is a member that fixes the wall body 2, and it is necessary to reliably and smoothly transmit the load from the wall body 2 to the foundation ground. In addition, since the debris flow enters the opening 10 between them, the interval becomes large, so that the bottom slab 4 is made of reinforced concrete so that it can resist the shearing force and bending moment generated between the wall bodies by the ground reaction force. Yes.
[0055]
(iv) Top version 5
The top plate 5 in this embodiment has a role of helping to fix the wall body 2 together with the bottom plate 4, but is made of reinforced concrete as a relatively strong member because it receives its own weight or load of debris flow.
[0056]
According to the transmission type sabo dam 1 of the present embodiment configured as described above, the effects listed below can be achieved.
[0057]
(1) Because there is no restriction due to the boulder diameter of the slit interval, which was a disadvantage of the concrete dam with a conventional slit, it can be adjusted by the interval of the beam material 3 and the interval between the openings 10 is sufficiently secured. In the normal condition, the medium pebbles can be passed without clogging, the screen effect can be maintained for a long time, and the boulders can be captured efficiently.
[0058]
(2) The wall body 2 has a structure that is resistant to debris flow wear and collision, and is constrained by the bottom plate 4 and the top plate 5 so that it can have a high safety against debris flow.
[0059]
(3) Sand and gravel accumulate between the walls 2 and 2, and the beam material 3 is hardly subjected to sediment pressure due to its inclined arrangement, and the impact force is mitigated by the deformability of the member and its fixing method. Therefore, the cross section can be reduced together with the wall body 2, and an economical member design can be performed.
[0060]
(4) The beam 3 is easy to replace, excellent in maintenance and management, high safety when left after being filled with sand, and high long-term function.
[0061]
Modification of the embodiment
(a) Although the wall body 2 illustrated the structure which consists of an outer shell, a filling material, and a cover material, it is not restricted to this, An unreinforced concrete structure, a reinforced concrete structure, a steel frame structure, a steel frame reinforced concrete structure, etc. may be sufficient.
[0062]
Although the outer shell which comprises the wall body 2 illustrated the steel plate, it is not restricted to this, For example, members other than a steel plate, such as a shape steel, another metal, resin, or a concrete panel, may be sufficient.
[0063]
The filling material constituting the wall body 2 is exemplified by soil cement, but is not limited thereto, and other materials than the soil cement, such as gravel material, sandy soil, hard material such as concrete, crushed stone and cobblestone, etc. Cohesive soil may be used.
[0064]
The cover member constituting the wall body 2 is a concrete member, but is not limited thereto, and may be a material other than concrete, for example, steel, other metal, or resin. Moreover, the case where a lid is not provided is also included in the present invention.
[0065]
Although the shape of the wall 2 is exemplified by a semi-oval shape, the shape is not limited to this, and other shapes may be used.
[0066]
(b) The beam 3 is exemplified by a circular steel pipe, but is not limited to this, and other steel members such as a square steel pipe, an H-shaped steel, a wire or a steel bar, or a concrete member such as reinforced concrete or prestressed concrete. Etc.
[0067]
The arrangement of the beam members 3 is illustrated as being aligned in a single row, but is not limited to this, and the present invention also includes a case in which some of the beams 3 are not aligned in a single row, such as bent or curved in a side view. It is.
[0068]
(c) Although the bottom plate 4 and the top plate 5 are made of reinforced concrete, the present invention is not limited to this example. For example, steel members, unreinforced concrete, soil cement, metal frames and frames, etc. It may be a stuffed product. Further, the case where no bottom plate or top plate is provided is also included in the present invention.
[0069]
(d) The dam was illustrated as an example of two independent walls and one row of beam members spanning them, but this is not the only case, and various forms can be taken depending on the width of the river to be constructed. it can. For example, as shown in FIG. 10, one or more openings may be formed in a wall body 2 ′ continuous in the direction perpendicular to the river axis, and the beam member 3 may be disposed in the opening. Three or more bodies may be arranged, and the wall body 2 and the beam material 3 may be alternately arranged, or a plurality of units of two wall bodies and one row of the beam material are arranged at intervals in the direction perpendicular to the river axis. May be.
[0070]
【The invention's effect】
(1) According to the transmission type sabo dam according to claim 1, earth and sand gravel enters and accumulates between walls during debris flow, and the sediment gradient after debris flow stops approximates the arrangement of inclined beams. Therefore, the sediment pressure applied to the beam material between the walls becomes smaller as the gradient becomes looser, the cross section of the wall body and the beam material can be reduced, and an economical transmission type sabo dam can be obtained. .
[0071]
(2) Since the shape of the sediment deposited between the walls acts as a counterweight against overturning in the direction of the river axis, it also has an advantageous effect on the overall stability of the transmission type sabo dam and reduces the cross section of the walls and bottom slab. Therefore, an economical transmission type sabo dam with excellent stability and safety can be obtained.
[0072]
(3) be increased twice or more falling-up gravel size net spacing of the wall each other as not to block at the upstream end of the wall, without entering the soil gravel into between walls is inhibited, During normal times, medium and small pebbles can pass without clogging, and the screen effect can be maintained for a long time. A relatively simple and inexpensive structure with walls and beams can secure a large sand storage capacity during debris flow, and also prevent gravel reflow due to rising water levels in mountain streams with high flow rates.
[0073]
(4) If the net interval between the beams is set to be 1.5 times or less the maximum gravel diameter in the debris flow so that the debris flow is blocked, the debris flow will not flow downstream, and the wall and beam material Due to the relatively simple and inexpensive structure, the boulders can be reliably captured.
[0074]
(5) If the beam material is damaged due to a gravel fall collision caused by a direct debris flow collision or overflow after overflow, it is easy to replace and restore the function if it is removable. Excellent management and high safety.
[0075]
(6) Since the beam material is inclined, the gravel that overflowed after the full sand is unlikely to increase in speed by falling so as to roll on a gentle slope, and it is filled with sand at the time of falling collision. Is supported by sedimentary earth and sand, so there is little risk of dropout of beam materials, high safety, and high long-term functionality.
[0076]
(7) When removing the beam material, because the beam material is located on the downstream side between the walls, and because the slope of sedimentation is gentle, the risk of slope failure is small. Easy to change materials.
[0077]
(8) According to the transmission type sabo dam according to claim 2 , it is possible to prevent a fall in a direction perpendicular to the river axis by providing a bottom plate or a top plate and connecting the wall bodies to each other.
[Brief description of the drawings]
[0078]
FIG. 1 is a perspective view showing an embodiment of a transmission type sabo dam according to the present invention.
2 is an exploded perspective view showing an example of a wall body of the transmission type sabo dam in FIG. 1. FIG.
FIG. 3 is a plan view showing a state on the upstream side of the wall body of FIG. 2;
FIGS. 4A and 4B are a side view and a reaction force distribution diagram showing a state where the dam of the present invention receives a load from the upstream side. FIGS.
FIG. 5 is a vertical sectional view showing a state in which earth and sand gravel has entered between the walls of the present invention.
FIG. 6 is a plan view of a partial cross section showing an example of a detachable beam member of the present invention.
FIG. 7 is a vertical sectional view showing the state of sediment accumulation by the beam material after the sediment flow stop of the present invention.
FIG. 8 is a vertical sectional view and a reaction force distribution diagram showing the action of the dam of the present invention due to sedimentation.
FIG. 9 is a vertical cross-sectional view showing the movement of gravel after full sanding of the dam of the present invention.
FIG. 10 is a plan view showing a modification of the transmission type sabo dam of the present invention.
FIG. 11 is a perspective view showing a conventional impervious gravity sabo dam.
FIG. 12 is a perspective view showing a transmission-type sabo dam having a conventional slit.
FIG. 13 is a perspective view showing a conventional transmission sabo dam made of steel pipe.
FIG. 14 is a perspective view showing a conventional transmission type sabo dam with slits and cross beams.
15 is a vertical sectional view showing damage to the bottom slab in the dam of FIG. 14. FIG.
16 is a vertical cross-sectional view showing a state of deposition inside a steel pipe lattice in the dam of FIG. 13;
[Explanation of symbols]
[0079]
DESCRIPTION OF SYMBOLS 1 ... Transmission-type sabo dam 2 ... Wall body 2a ... Outer shell 2b ... Filling material 2c ... Cover material 2d ... Cover material 3 ... Beam material 3a ... Main pipe 3b ... Sheath pipe 3c ... Joint part 4 ... Bottom plate 5 ... Top plate 10 ... Opening 11 ... Deposition space 12 ... Inclined surface 13 ... Buffer material

Claims (3)

A beam is spanned between walls of an opening having a predetermined width formed between the walls, and a plurality of beams are provided at predetermined intervals in the vertical direction on the downstream side of the opening. The both ends of the beam members are inserted into the opposite side surfaces of the wall body across the opening, and the beam members are arranged so as to be positioned on the upstream side as they are vertically upward. A transmission type sabo dam characterized by being configured to allow sand and gravel to invade and accumulate in a space surrounded by the side surface of the wall on the upstream side.   The transmission type sabo dam according to claim 1, wherein the wall body is provided with a bottom plate for fixing the wall body or a top plate for connecting the wall bodies.   The wall body and the beam material are alternately provided in the direction perpendicular to the river axis, or a plurality of sets of the wall body and the beam material are provided at intervals. The transmission type sabo dam as described in the item.

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