JP7154534B2 - Sabo dam - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sabo dam, and more particularly to a sabo dam for preventing debris flow disasters and sediment disasters.

Sabo dams are generally constructed in the shape of concrete gravity dams in order to reduce damage caused by sediment disasters, particularly debris flows, and are also called sabo dams. Therefore, both sleeves at both ends in the width direction of the valley (including the river) of the erosion control dam have a stable installation structure that is deeply buried in both banks, and the upper part of the dam that spans the entire width of the valley At the central portion in the width direction of the valley, an overflow portion called a water passage is formed. This type of erosion control dam has a rigid structure that can withstand not only large boulders and driftwood flowing at high speed but also fluid pressure in the event of a debris flow. In other words, there is also the problem of significantly altering the ground.

Therefore, permeable erosion control dams are attracting attention, in which an intermediate area such as a slit is provided at a predetermined location of the dam, and when a debris flow occurs, water flows downstream through this intermediate area to block out objects such as boulders and driftwood. . As such a permeable erosion control dam, for example, there is one described in Patent Document 1 below. This permeable sabo dam has an intermediate region with a relatively large opening formed between both sleeves of the dam, and is constructed by alternately providing a three-dimensional structure and a plane structure in this intermediate region to prevent the occurrence of a debris flow. Drifting materials such as boulders and driftwood of time are dammed by each structure.

JP 2013-204272 A

The erosion control dam described in Patent Document 1 is also a rigid structure that does not allow deformation of each structure that dams down objects such as boulders and driftwood when a debris flow occurs, and it is necessary to construct a concrete structure to receive these structures. be. Such concrete structures are huge and generally difficult to construct without construction roads, so conventional erosion control dams can only be constructed relatively downstream of the debris flow source. However, most of the sources of debris flows are the uppermost reaches of rivers and small valleys near mountain tops or in deep mountain valleys without regular surface water, such as dry valleys. In large-scale valleys, there are no construction roads, and erosion control dams with huge concrete structures cannot be constructed.

In other words, for example, a debris flow that occurs near a summit or in a small-scale valley in a deep mountain flows downstream, entraining trees and rocks on the shore, and becomes larger as it goes downstream, resulting in movement of the debris flow. energy will also increase. Therefore, the erosion control dam constructed on the downstream side of the river must have a robust structure in order to receive this huge kinetic energy. In other words, in order to effectively reduce the damage caused by a debris flow, it is necessary to accurately remove debris from a debris flow immediately after it occurs, especially in areas where the kinetic energy of the debris flow is still small, such as near mountain tops and in small valleys between deep mountains. A sabo dam is desirable.

The present invention has been made in view of the above problems, and its object is to be able to construct even small-scale valleys without the need for concrete structures, and as a result, effectively reduce damage caused by debris flows. To provide an erosion control dam capable of

In order to achieve the above object, the erosion control dam according to claim 1,
A erosion control dam provided in a valley sandwiched by natural ground, wherein a rope is bridged between both ends in the width direction of the valley and both ends are respectively fixed to the natural ground, and the rope is engaged with the rope. By doing so, the net body stretched from the bottom of the valley to a predetermined height position and stretched substantially in the width direction of the valley and both ends of the rope are fixed to the ground. fixing means, wherein the fixing means includes an anchor driven on the surface of the natural ground so as to reach a stabilization stratum deeper than the slip surface of the natural ground, and the head of the anchor is inserted through the anchor. a pressure plate that is fixed and abuts against the surface of the natural ground while being pressed by the tension force of the anchor; and connecting means that connects the pressure plate or the anchor and the end of the rope. It is characterized by

According to this configuration, the net body is engaged with the rope whose both ends are fixed to the natural ground, and the net body is stretched substantially in the width direction of the trough. Therefore, when a debris flow occurs, the net blocks the flowing objects such as boulders and driftwood that flow in the valley. Drainage can be dammed. Therefore, it is possible to construct a dam, for example, near a mountain top or in a small-scale valley between deep mountains without requiring a huge concrete structure. In addition, the pressure receiving plate not only receives the reaction force of the force related to the anchor, but also covers the surface of the ground so as to press it, so it suppresses the collapse of the ground surface, which is one of the causes of large-scale debris flows. It is possible to protect the ground surface and thereby suppress the enlarging of debris flows.

The erosion control dam according to claim 2 is the erosion control dam according to claim 1, wherein a plurality of the ropes are arranged in the height direction of the valley, and the lower the rope in the height direction, the higher the rope. It is characterized in that the slack is set large.

According to this configuration, the capacity for accommodating the falling objects, which is composed of the net body and the rope that are deformed as the falling objects are captured when a debris flow occurs, increases in the downward direction in the height direction. can be captured by

The sabo dam according to claim 3 is the erosion control dam according to claim 1 or 2, wherein a plurality of ropes are arranged in the height direction of the valley, and the lower the rope in the height direction, the higher the rope. The rope is characterized in that the allowable elongation amount of the length between the fixing portions at both ends is set larger than that of the rope.

According to this configuration, the rope elongation due to the deformation of the net body that caught the falling object when a debris flow occurred is greater for the lower rope in the height direction. The object storage volume increases downward in the height direction, making it possible to stably capture a larger amount of falling objects.

The sabo dam according to claim 4 is characterized in that, in the sabo dam according to any one of claims 1 to 3, the lower end of the net body is fixed to the bottom of the valley.

According to this configuration, when a debris flow occurs, it is possible to prevent the lower end of the net body, which dams up debris such as boulders and driftwood, from being turned up. It is possible to prevent them from flowing downstream, and to reliably dam them up with the net body.

The erosion control dam according to claim 5 is the erosion control dam according to any one of claims 1 to 4, wherein when a load equal to or greater than a predetermined value is applied to the rope, the load is applied with a predetermined braking force. It is characterized in that a braking device is provided to allow the extension of the length of the rope.

According to this configuration, when a large load is applied to the rope, the elongation of the rope is allowed while a predetermined braking force is applied. becomes possible. As a result, the kinetic energy of the falling objects such as debris flow can be more accurately absorbed, and the entire net body including the rope can more reliably dam the falling objects. The sabo dam according to claim 6 is characterized in that the pressure receiving plate has a longitudinal length of 1 m or more and 3 m or less in a plan view.

As described above, according to the present invention, when a debris flow occurs, the net blocks flowing objects such as boulders and driftwood, and at that time, the deformation performance of the net absorbs the kinetic energy of the debris flow. Therefore, the entire net body can dam the flowing material. In addition, by covering the ground surface so as to press the pressure receiving plate, it is possible to protect the ground surface and suppress an increase in the size of the debris flow. As a result, it is possible to build effective dams even in small-scale valleys without the need for concrete structures, thereby effectively reducing damage caused by debris flows while preserving the landscape and environment.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partially cross-sectional front view showing the overall configuration of an embodiment of a erosion control dam of the present invention; FIG. 2 is a perspective view of fixing means used in the erosion control dam of FIG. 1; FIG. 2 is a perspective view showing an example of a ring-shaped member used in the ring-type net of FIG. 1; 1. It is a partial cross-sectional side view which shows the state which dammed the flowing material with the sabo dam of FIG. FIG. 4 is an explanatory diagram showing another example of a net body applicable in the present invention;

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the sabo dam of this invention is described in detail with reference to drawings. FIG. 1 is a partial cross-sectional front view showing the overall construction of the erosion control dam of this embodiment. The erosion control dam according to this embodiment, like the existing sabo dam, extends in the width direction of the valley for the purpose of preventing damage caused by sediment disasters, especially debris flows. In the embodiment, the object is to construct a relatively narrow trough portion R sandwiched by ground H on both sides in the width direction. The "relatively narrow valley R sandwiched between natural grounds H" particularly refers to relatively small-scale valleys where it is difficult to construct a concrete structure, such as the vicinity of a summit or a valley between deep mountains. . It should be noted that the troughs R defined in this embodiment may or may not have water flow. The valley R shown in the figure is a so-called dry stream in which water does not normally flow (always surface water). However, when it rains, debris flow may occur.

In this erosion control dam, a net body consisting of a ring-type net 18, which will be described later, is extended from the bottom portion B side of the valley portion R to a predetermined height position in order to dam up debris such as boulders and driftwood when a debris flow occurs. and stretched between ground H on both sides of the valley R in the width direction. As will be described later, the ring-type net 18 of this embodiment is constructed by connecting ring-shaped members 20 each formed by winding a steel wire a plurality of times, for example. Any net body can absorb the kinetic energy of the falling material by deforming itself, but the ring-shaped member 20 that constitutes the ring-type net 18 in particular has a large amount of deformation that can be allowed. It has the advantage that the kinetic energy that can be absorbed is large. In FIG. 1, the ring-shaped member 20 of the ring-type net 18 is partly omitted for the sake of easy understanding, but the ring-shaped member 20 of the ring-type net 18 covers the entire stretched area of the net body. are arranged as follows.

In order to stretch the ring-type net 18 in the width direction of the valley R, in this embodiment, a plurality of ropes 26 (three in the drawing) are stretched between both ends of the valley R in the width direction. The rope 26 and the ring-type net 18 are engaged. A high-strength wire rope, for example, is applied to the rope 26 . The wire diameter of the rope 26 is, for example, approximately 12 to 30 mm. The three ropes 26 are arranged at predetermined intervals downward in the height direction with the predetermined height position as the uppermost position, and each rope 26 is arranged, for example, in the ring of the ring-shaped member 20 of the ring-type net 18. It is engaged by inserting it into the Therefore, the engagement height position between the uppermost rope 26 and the ring-type net 18 is the upper end of the ring-type net 18 .

In addition, it is desirable to connect the ring-shaped member 20 and the rope 26 at the insertion portion of the rope 26 . Alternatively, the rope 26 may be locked to the ring-shaped member 20 by using a separate locking tool called, for example, a shank or jaw, without passing through the ring member of the ring-type net 18 . In addition, the rope 26 at the upper end of the net body tensioning area supports, for example, the ring-type net 18 by suspending it. It not only supports the net 18 but also exhibits the function of reinforcing the ring-type net 18 when the ring-type net 18 dams up the flowing material. In other words, the kinetic energy of the falling material when a debris flow occurs is absorbed by the deformation of the ring-type net 18 but is also transmitted to the rope 26 . The kinetic energy transmitted to the rope 26 can be dealt with by firmly fixing the rope 26 to the natural ground H, or by applying a braking force to the elongation while allowing the elongation of the rope 26. , the ring-type net 18 can be reinforced.

In this embodiment, as is clear from the figure, the lower rope 26 in the height direction has more slack than the upper rope 26 . This is for the purpose of increasing the capacity of the ring-type net 18 and the rope 26 to contain the falling material, that is, the volume of the pocket, when the ring-type net 18 that dams up the falling material is deformed, as will be described later. . Further, in this embodiment, the lower the rope 26, the greater the allowable amount of elongation between both end fixing portions of the rope 26 by the brake device 30, which will be described later. This is also for the purpose of increasing the volume of the falling matter by the ring-type net 18 and the rope 26, that is, the volume of the pocket, toward the bottom.

Both ends of each rope 26 are fixed to the ground H on both sides of the valley R in the width direction by fixing means 2 . These fixing means 2 are, for example, as shown in FIG. A connecting means 5 for connecting the pressure receiving plate 4 and the end of the rope 26 is provided. The pressure-receiving plate 4 is made of, for example, a thick plate material made of metal, concrete, or plastic. something already exists. The size of the pressure receiving plate 4 is, for example, about 1 to 3 m across the cross. A turnbuckle member, for example, is used as the connecting means 5 . For example, in the pressure receiving plate 4 of FIG. 2, connecting eyebolts 6 are provided at each of the four corners of the cross-shaped central connecting portion. These eyebolts 6 and the ends of the ropes 26 are connected by connecting means 5 such as turnbuckle members. A wire rope or the like can also be applied to the connecting means 5 .

The anchor 3 of this embodiment is made of, for example, a steel bar, and is inserted into an anchor hole 7 drilled from the surface of the natural ground H to the stabilization stratum D. Cement milk 8 is injected into the anchor hole 7. It is hardened and fixed to the natural ground H. The diameter of the anchor hole 7 is approximately 120 mm, the diameter of the anchor 3 is approximately 50 mm, and the depth of the anchor hole 7 is approximately 7 to 30 m. As is well known, in the ground H on a steep slope, there is a risk that the unstable layer T of the surface layer may slide down along the slip surface indicated by the dashed line in the figure. Therefore, generally, the anchor 3 is placed so as to reach the stabilization stratum D which is deeper than the slip surface. That is, when the cement milk 8 hardens in the anchor hole 7 reaching the stabilization stratum D of the ground H, the anchor 3 is integrated with the stabilization stratum D.

In this embodiment, the pressure-receiving plate penetrating portion of the anchor 3 is formed with a male thread, and after the anchor 3 is inserted into the through-hole of the pressure-receiving plate 4, for example, a seat cap nut 9 is screwed into the male screw. By tightening, the pressure receiving plate 4 is pressed against the surface of the ground H, whereby the anchor 3 is inserted and fixed to the pressure receiving plate 4 . Therefore, the pressure receiving plate 4 that abuts on the surface of the ground H is fixed to the ground H by the anchor 3 so as to press the surface of the ground H. As shown in FIG. For example, a cap shown by a dashed line in the figure is attached to the projection of the anchor 3 passing through the pressure receiving plate and the cap nut 9, and the inside of the cap is filled with grease for rust prevention. Alternatively, a liquid absorbing cushion may be interposed between the pressure receiving plate 4 and the surface of the ground H, and the cement milk may be injected and solidified into this cushion. Also, an existing anchor construction method using a plurality of PC steel stranded wires may be used instead of steel bar anchors.

When the ring-shaped member 20 is deformed by receiving the falling material, the ring-shaped net 18 as a whole bulges downstream. At that time, the lower end of the ring-type net 18 that bulges downstream does not roll up, and the liquid does not flow out from the lower side of the ring-type net 18 to the downstream side. The ring-shaped member 20 at the upstream end is fixed to the bottom B of the valley R by an anchor pin 38 (see FIG. 4).

The actual rope 26 is slackened downward due to its own weight and the weight of the ring net 18, as shown in FIG. This amount of slack makes it possible to adjust the restraint of the falling material by the ring-type net 18 and the restraining of the flowing material by the rope 26 engaged with it. That is, since the rope 26 is engaged with the ring-shaped member 20 of the ring-type net 18, the movement of the rope 26 and the movement of the ring-type net 18 are linked to each other when debris flow occurs.

The effect of absorbing the kinetic energy of debris flow due to the deformation of the ring-type net 18, which will be described in detail later, is exhibited when the net is no longer flexed and the ring-shaped member 20 is deformed. On the other hand, the ring-type net 18 catches the falling material, and the ring-type net 18 bulges downstream so that the rope 26 loses its slack, and the rope 26 begins to exert a tension greater than its own weight. can support At this time, if the elongation of the rope 26 is permitted and a braking force is applied to the elongation, the kinetic energy of the debris flow can be absorbed by the elongation of the rope 26 accompanied by the braking force. For this reason, both ends of the rope 26 are provided with braking devices 30 that allow the length between the fixed portions of the rope to extend with a predetermined braking force. In this embodiment, as described above, the allowable elongation amount of the length between both fixed portions of the rope 26 by the brake device 30 is set larger for the lower rope 26 .

This brake device 30 regulates the movement of the rope 26 in the longitudinal direction, for example, in normal times. When a debris flow occurs, the ring-type net 18 catches the falling material and bulges downstream to eliminate the slack in the rope 26, increasing the tension of the rope 26. - 特許庁When this tension becomes larger than the restraining force of the rope 26 by the brake device 30, for example, the rope 26 slips within the brake device 30, and the frictional resistance associated with the slip becomes the braking force, and the kinetic energy of the debris flow is reduced by this braking force. be absorbed.

In this embodiment, the amount of elongation of the rope 26 by these braking devices 30 is set so that the elongation of the length between both fixed portions of the rope 26 reaches the limit at the same time as or before the deformation limit of the ring-type net 18. set. With this configuration, the deformation limit of the ring-type net 18 is reached at the same time as or after the elongation limit of the length between the fixed portions of the rope 26, so the kinetic energy of the debris flow is absorbed by the elongation of the rope 26 accompanied by the braking force. The deformation of the ring-type net 18 can absorb the excess kinetic energy of debris flow.

For example, when the elongation limit of the rope 26 accompanied by the braking force of the brake device 30 is set to the kinetic energy absorption upper limit value of the debris flow, if the debris flow has kinetic energy exceeding this limit, the rope 26 will be fully stretched. After that, the deformation of the ring-type net 18 can absorb the kinetic energy exceeding the upper limit value, thereby suppressing the falling matter. In addition, if the ring-type net 18 does not reach its deformation limit when a debris flow occurs, the rope 26 can be replaced and the ring-type net 18 can be reused as it is. Become.

For example, as shown in FIG. 1, when a plurality of braking devices 30 are provided for each rope 26, the magnitudes of the braking forces of the braking devices 30 may be set to different magnitudes. . With such a braking force distribution, for example, when two braking devices 30 are provided for one rope 26, one of the braking devices 30 operates first to exert a braking force, and then the other brake device 30 operates. brake device 30 operates to exert a braking force. By doing so, it is possible to exert braking force continuously or intermittently, that is, continue to absorb kinetic energy while the rope 26 supporting the falling material continues to stretch.

Next, the ring-type net 18 used in this embodiment will be described. The ring-type net 18 is similar to that described in, for example, Japanese Patent Laying-Open No. 2014-1584 (hereinafter also referred to as prior art document), and is configured by connecting a plurality of ring-shaped members 20 to each other. In this embodiment, for example, as can be seen from FIG. Connect so that the peripheral sides are in contact with each other. The connection structure of the ring-shaped member 20 has various forms as described in prior art documents.

FIG. 3 is a perspective view showing an example of a ring-shaped member 20 used in the ring-type net 18 of FIG. The ring-shaped member 20 is constructed by winding a wire rod 22 made of, for example, a steel wire a plurality of times (5 to 20 times) and tightening it with fasteners 24 at several points in the circumferential direction. The fastener 24 is, for example, a substantially cylindrical metal fitting having a C-shaped side surface, and is fixed by covering the outside of the wire rod 22 that is superimposed by winding and then crimping. This ring-shaped member 20 is also the same as that described in the above-mentioned prior art document. By adjusting , it is possible to adjust the strength and energy absorption capacity during deformation, which will be described later.

The wire rod 22 forming the ring-shaped member 20 is preferably a steel wire manufactured from, for example, a hard steel wire rod, but may be an iron wire manufactured from, for example, a mild steel wire rod. Steel wire preferably has a tensile strength of 800 N/mm ² or more. Moreover, those obtained by plating or coating these wires 22 can also be used. The diameter of the wire rod 22 is about 2.5-5 mm, and the diameter of the ring-shaped member 20 is about 300-1500 mm. By changing the diameter of the ring-shaped member 20, the ring-type net 18 can easily correspond to the size of the falling objects (boulders) to be dammed up. For example, if the size of the boulders upstream is investigated and the diameter of the ring-shaped member 20 is set according to the size, it is possible to effectively block the falling objects when a debris flow occurs.

In the ring-type net 18 configured by connecting the ring-shaped members 20, for example, when a force (load) perpendicular to the surface of the net is applied, the ring-shaped members 20 are pulled together, so the shape of the ring-shaped members 20 themselves is deformed. At the same time, the winding of the wire rod 22 forming the ring-shaped member 20 is deformed so as to loosen. These deformations are caused by the kinetic energy of the debris flow, specifically when the load acts on the net surface due to the collision of boulders and driftwood. , the kinetic energy of the debris flow is absorbed, and as a result, the ring-type net 18 as a whole has the effect of blocking boulders and driftwood. Since a debris flow occurs from the upstream side to the downstream side of a mountain stream, the ring-type net 18, in which the ring-shaped member 20 is deformed by the kinetic energy of the debris flow, bulges downstream when subjected to the debris flow, as described above. .

From these facts, it can be said that the erosion control dam using the ring-type net 18 is a "flexible structure" that receives the kinetic energy of the debris flow due to the deformation of the ring-shaped member 20. It is different from the “rigid structure” of permeable erosion control dams. In the case of this embodiment, if the movement of the falling material can be restrained by the entire ring-type net 18, including the rope 26 and the brake device 30, then the rope 26 and the ring-type net 18 are tied. The load received by the fixing means 2 is the static load of the flowing material. As is well known, the static load on the same object is much smaller than the dynamic load. Therefore, even with a simple structure, the fixing means 2 can continue to support the ring-type net 18 and the rope 26 that dammed the falling material, so that a foundation or frame made of a so-called concrete structure is not required. . Therefore, even in the valley R where it is difficult to construct a concrete structure, a erosion control dam can be constructed, and the construction is greatly facilitated. This ease of construction brings great merit in places where dams are constructed, that is, in mountainous areas.

FIG. 4 is a partial cross-sectional side view showing a state in which the erosion control dam 1 of FIG. As described above, the ring-type net 18 that has dammed the falling material bulges downstream as the ring-shaped member 20 deforms (extends). In this embodiment, among the three ropes 26, the slack of the lower rope 26 in the height direction is greater than the slack of the upper rope 26, and the allowable elongation of the lower rope 26 is is set to be larger than the allowable elongation of the , the volume of the falling matter storage composed of the ring-type net 18 and the rope 26 that deforms to bulge downstream, that is, the volume of the pocket that receives the falling matter, is equal to the height Larger in the downward direction. Therefore, a large amount of the falling matter is stably stored in the large lower pocket, so that a large amount of the falling matter can be stably captured. In addition, since the pressure receiving plate 4 for fixing the rope 26 to the ground H covers the surface of the ground H so as to press it, the valley bank, which is one of the causes of the enlarging debris flow, i.e. It is possible to suppress the collapse of the surface, thereby suppressing the enlarging of the debris flow. It should be noted that it is possible to increase the storage capacity of the falling material downward in the height direction by setting either the slackness of the rope 26 or the allowable elongation amount.

As described above, according to the erosion control dam of this embodiment, the ring-type net 18 is engaged with the rope 26 whose both ends are fixed to the natural ground H, and the ring-type net 18 extends substantially in the width direction of the valley R. Since it is stretched, when a debris flow occurs, the ring-type net 18 dams the falling objects such as boulders and driftwood flowing in the valley R, and at that time, the deformation performance of the ring-type net 18 absorbs the kinetic energy of the debris flow. As a result, the ring-type net 18 as a whole can dam up the falling matter. Therefore, it is possible to construct a dam even in the vicinity of a mountain top or in a small-scale valley R between deep mountains, for example, without requiring a huge concrete structure. Further, the pressure receiving plate 4 for fixing the rope 26 to the surface of the natural ground H not only receives the reaction force of the force related to the anchor 3, but also covers the surface of the natural ground H so as to press it. It is possible to protect the ground surface by suppressing the collapse of the ground surface, which is one of the causes of the gigantic size, and thereby suppressing the gigantic size of the debris flow.

In addition, the lower the rope 26 in the height direction, the more slack is set than the upper rope 26, so that the ring-type net 18 and the rope 26 deformed as they caught the falling objects when debris flow occurred. Since the object storage volume increases downward in the height direction, it is possible to stably capture a larger amount of falling objects.

In addition, the lower the rope 26 in the height direction, the larger the allowable elongation of the length between the fixed parts at both ends than the upper rope 26, so that the ring-type net 18 that catches the falling objects when a debris flow occurs is deformed. Since the elongation of the rope 26 due to the height direction is greater in the lower rope 26 in the height direction, the flow-down material storage volume composed of the deformed ring-type net 18 and the elongated rope 26 increases in the height direction downward. It is possible to stably capture a larger amount of objects.

In addition, by fixing the lower end of the ring-type net 18 to the bottom B of the valley R, the lower end of the ring-type net 18, which dams up falling objects such as boulders and driftwood, is prevented from being turned up when a debris flow occurs. As a result, it is possible to prevent the falling objects from flowing downstream from under the ring-type net 18 when a debris flow occurs, and the ring-type net 18 can reliably dam them up.

In addition, a large load is applied to the rope 26 by providing the rope 26 with a braking device 30 that allows the length of the rope 26 to expand while applying a predetermined braking force when a load of a predetermined value or more is applied. Since the elongation of the rope 26 is permitted with a predetermined braking force, it is possible to secure the braking action, that is, the ability to absorb kinetic energy as the rope 26 elongates. As a result, the kinetic energy of the falling objects such as debris flow can be more accurately absorbed, and the entire ring-type net 18 including the rope 26 can more reliably dam the falling objects.

Although the embodiments have been described above, the configuration of the present invention is not limited to these embodiments, and various modifications are possible within the scope of the invention. For example, the number and material of the ropes 26 described above are appropriately selected according to the situation of the site, and their braking devices are not limited to the above-described configuration, and are accompanied by braking force. Anything that allows the rope 26 to stretch may be used.

Further, in the above-described embodiment, only one ring-type net 18 is stretched between the natural grounds H, but a plurality of ring-type nets 18 may be stretched between the natural grounds H.

Furthermore, instead of the ring-type net 18, it is also possible to apply another net body. As such a net body, for example, as shown in FIG. 5, a rhombic metal wire mesh 26 made of a rhombic metal wire can be used as the net body. As described in Japanese Unexamined Patent Application Publication No. 2016-37773, for example, the rhombic wire mesh 26 is formed by bending a metal wire 28 into triangular wavy wires, and forming peaks and valleys of a plurality of triangular wavy wires arranged in parallel. It is constructed by interweaving and engaging those triangular wavy wires. Soft steel, hard steel, spring steel, stainless steel, or the like can be used for the metal wire 28 that constitutes the triangular wavy wire. If necessary, the metal wire 28 may be coated to prevent wear and corrosion of the contact portion of the triangular-wavy wire. The coating treatment includes, for example, galvanizing treatment and polyester coating treatment. Any net body including this rhombic wire mesh 26 can be used for the net body of the present invention as long as it can dam up the flowing material.

2 fixing means 3 anchor 4 pressure receiving plate 5 connecting means 7 anchor hole 8 cement milk 18 ring type net (net body)
20 Ring-shaped member 26 Rope 30 Brake device 38 Anchor pin H Natural ground R Valley B Bottom D Stabilizing stratum

Claims (6)

An erosion control dam provided in a valley sandwiched by natural ground,
a rope that is stretched between both ends in the width direction of the valley, and both ends are respectively fixed to the ground;
a net body that is stretched in a region from the bottom of the valley to a predetermined height position by being engaged with the rope and stretched substantially in the width direction of the valley;
fixing means for fixing both ends of the rope to the ground;
The fixing means are
an anchor placed on the surface of the natural ground so as to reach a stabilization stratum deeper than the slip surface of the natural ground ;
a pressure receiving plate, through which the head of the anchor is inserted and fixed, and which abuts against the surface of the natural ground while being pressed by the tension of the anchor ;
An erosion control dam, comprising a connection means for connecting the pressure plate or the anchor and the end of the rope. A plurality of the ropes are arranged in the height direction of the valley,
2. The erosion control dam according to claim 1, wherein a lower rope in the height direction is set to have a larger slack than an upper rope. A plurality of the ropes are arranged in the height direction of the valley,
The sabo dam according to claim 1 or 2, wherein the lower the rope in the height direction, the larger the permissible elongation of the length between the fixed portions at both ends than the upper rope. The sabo dam according to any one of claims 1 to 3, wherein a lower end portion of said net body is fixed to a bottom portion of said valley portion. 5. The rope according to any one of claims 1 to 4, further comprising a braking device that allows the length of the rope to extend while applying a predetermined braking force when a load of a predetermined value or more is applied. or the erosion control dam according to item 1. The erosion control dam according to any one of claims 1 to 5, wherein the pressure plate has a longitudinal length of 1 m or more and 3 m or less in plan view.

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