JP2019218723A - Sand control dam - Google Patents

Abstract

To provide a sand control dam that does not require a concrete structure and, as a result, can be built even in a valley sandwiched between natural grounds.SOLUTION: A ring-type net 18 extending from a bottom B side of a valley R sandwiched between natural grounds H to a predetermined height position is stretched between the natural grounds H, a rope 26 engaged with the ring-type net 18 is bridged between the natural grounds H in the stretched area of the ring-type net 18, and both ends of the rope 26 are fixed to the natural grounds H by fixing means 2. The fixing means 2 inserts and fixes an anchor 3 cast on the natural ground to a pressure receiving plate 4 which is in contact with the surface of the natural ground H, and connects the pressure receiving plate 4 or the anchor 3 and the end of the rope 26 by connecting means 5 such as a turnbuckle member.SELECTED DRAWING: Figure 1

Description

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

  The sabo dam is generally provided in the shape of a gravity concrete dam in order to reduce the damage caused by landslide disasters, particularly debris flow, and is also called a sabo dam. Therefore, both sleeves at both ends of the valley (including rivers) in the width direction of the sabo dam have a stable installation structure buried deep in both shores. At the center of the valley in the width direction, an overflow section called water passage is formed. This type of sabo dam has a rigid structure that can reliably receive fluid pressure in addition to falling materials such as boulders and driftwood that flow at a high speed when debris flow occurs. In short, there is also the problem of significantly altering the ground.

  Therefore, an intermediate area such as a slit is provided at a predetermined position of the dam, and when a debris flow occurs, water flows downstream through the intermediate area, and a permeation type sabo dam that blocks a falling material such as boulders and driftwood has been attracting attention. . As such a transmission type sabo dam, for example, there is one described in Patent Document 1 below. This transmission type sabo dam is formed by forming a relatively large opening intermediate area between both sleeves of the dam, and alternately providing a three-dimensional structure and a plane structure in the intermediate area to generate debris flow. Downstream objects such as boulders and driftwood are blocked by each structure.

JP 2013-204272 A

  The sabo dam described in Patent Literature 1 is also a rigid structure in which deformation of each structure that blocks falling objects such as boulders and driftwood when debris flow occurs is not allowed, and it is necessary to construct a concrete structure that receives these structures. is there. Since such concrete structures are huge and generally difficult to construct without construction roads, conventional sabo dams can be constructed only relatively downstream from the debris flow source. However, many sources of debris flow are always in the uppermost stream of rivers, and in small valleys near the summits or deep hills without surface water, such as dry valleys. In large valleys, there are no construction roads and sabo dams with huge concrete structures cannot be built.

  In other words, for example, debris flows generated in small valleys near the summit or between deep mountains, while flowing downstream, encroach on trees and rocks on the shore and become larger as they go downstream, and the movement of debris flow Energy also increases. Therefore, the sabo dam built downstream of the river must have a robust structure to receive this huge kinetic energy. In other words, in order to effectively reduce the damage caused by debris flow, the kinetic energy of the debris flow is still small, for example, in the small valley near the summit or deep mountain, the debris flow of the debris flow immediately after the occurrence is precisely A sabo dam to be blocked is desired.

  The present invention has been made in view of the above problems, and has as its object the need for a concrete structure and the construction of a small-scale valley, thereby effectively reducing damage caused by debris flow. It is to provide a sabo dam that can be used.

To achieve the above object, the sabo dam according to claim 1,
A sabo dam provided in a valley sandwiched between grounds, which is bridged between both ends in the width direction of the valley, and both ends of which are fixed to the ground and engaged with the rope. By doing so, the net body extended to the region 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, the fixing means is an anchor cast on the surface of the ground, the anchor is inserted and fixed, a pressure receiving plate abutting on the surface of the ground, the pressure receiving plate or Connecting means for connecting an anchor and an end of the rope.

  According to this configuration, the net body is engaged with the rope whose both ends are fixed to the ground, and the net body is stretched substantially in the width direction of the valley. Therefore, when debris flow occurs, falling objects such as boulders and driftwood flowing in the valley are blocked by the net body, and at this time, the kinetic energy of the debris flow is absorbed by the deformation performance of the net body, and the entire net body It can block downflows. Therefore, a giant concrete structure is not required, and for example, it becomes possible to construct a dam even in a small valley near a mountaintop or in a deep mountain. In addition, because 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, it suppresses the collapse of the ground surface, which is one of the causes of the huge debris flow. It is possible to protect the surface of the ground and to suppress the huge debris flow.

  In the sabo dam according to claim 2, in the sabo dam according to claim 1, the plurality of ropes are disposed in a height direction of the valley, and a lower rope in the height direction is higher than an upper rope. The slack is set large.

  According to this configuration, the falling material storage volume composed of the net body and the rope deformed in accordance with the catching of the falling material at the time of debris flow increases as the height decreases downward, so that a larger amount of the falling material is stable. And capture it.

  The sabo dam according to claim 3 is the sabo dam according to claim 1 or 2, wherein a plurality of the ropes are disposed in a height direction of the valley portion, and the lower the rope in the height direction, the higher the rope. It is characterized in that the allowable extension of the length between the fixed portions at both ends is set to be larger than that of the rope.

  According to this configuration, since the elongation of the rope accompanying the deformation of the net body that catches the falling material when the debris flow occurs, the lower the rope in the height direction, the greater the rope elongation, so the downward flow composed of the deformed net body and the elongated rope The material storage volume becomes larger downward in the height direction, and it becomes possible to stably capture a large amount of the falling material.

  A sabo dam according to a fourth aspect is the sabo dam according to any one of the first to third aspects, wherein a lower end of the net body is fixed to a bottom of the valley.

  According to this configuration, when the debris flow occurs, it is possible to prevent the lower end of the net body blocking the inflow material such as boulders and driftwood from turning up, so that the debris flow when the debris flow occurs from below the net body. It is possible to prevent them from flowing downstream, and it is possible to reliably block them with a net body.

  The sabo dam according to claim 5 is the sabo dam according to any one of claims 1 to 4, wherein the rope is accompanied by a predetermined braking force when a load equal to or more than a predetermined value is applied to the rope. It is characterized in that a brake device that allows extension of the length of the rope is provided.

  According to this configuration, when a large load is applied to the rope, the elongation of the rope is allowed with a predetermined braking force. Therefore, the braking action, that is, the absorption of kinetic energy is secured with the elongation of the rope. Becomes possible. This makes it possible to more accurately absorb the kinetic energy of a falling object such as a debris flow, and the falling object can be more reliably blocked by the entire net body including the rope.

  As described above, according to the present invention, when debris flow occurs, falling objects such as boulders and driftwood are blocked by the net body, and at that time, the kinetic energy of the debris flow is absorbed by the deformation performance of the net body. Thereby, the flow-down material can be blocked by the entire net body. In addition, the pressure receiving plate covers the ground surface so as to press the ground surface, thereby protecting the ground surface and suppressing a huge debris flow. As a result, a concrete dam is not required, and an effective dam can be constructed even in a small valley. Thus, it is possible to effectively reduce damage caused by debris flow while preserving the landscape and the environment.

BRIEF DESCRIPTION OF THE DRAWINGS It is a partial cross-section front view which shows the whole structure of one Embodiment of the sabo dam of this invention. It is a perspective view of the fixing means used for the sabo dam of FIG. It is a perspective view which shows an example of the ring-shaped member used for the ring type net of FIG. FIG. 2 is a partial cross-sectional side view showing a state in which a falling material is blocked by the sabo dam of FIG. 1. It is explanatory drawing which shows the other example of the net body applicable to this invention.

  Hereinafter, embodiments of a sabo dam according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional front view showing the entire configuration of a sabo dam according to this embodiment. The sabo dam according to this embodiment is, like the existing sabo dam, extended in the width direction of the valley for the purpose of preventing sediment-related disasters, particularly damage caused by debris flow. In the embodiment, an object is to construct a relatively narrow valley portion R sandwiched between ground mountains H on both sides in the width direction. The “relatively narrow valley R sandwiched between the mountains H” particularly refers to a relatively small valley where it is difficult to construct a concrete structure, for example, a valley near a peak or a deep mountain. . The valley R defined in the present embodiment does not matter whether water flows. The illustrated valley portion R is a so-called dry flow where there is no water flow (normal surface water) at normal times. However, debris flows may occur during rainfall.

  In this sabo dam, a net body composed of a ring-type net 18 to be described later is extended from the bottom B side of the valley R to a predetermined height position in order to block down flowable substances such as boulders and driftwood when debris flow occurs. And stretched between the grounds H on both sides in the width direction of the valley R. As will be described later, the ring-type net 18 of this embodiment is configured by connecting, for example, ring-shaped members 20 each formed by winding a steel wire a plurality of times. Each of the net bodies is capable of absorbing the kinetic energy of the falling object by deforming itself, but in particular, the ring-shaped member 20 constituting the ring-type net 18 has a large allowable deformation amount. This 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 partially omitted for easy understanding, but the ring member 20 of the ring-type net 18 covers the entire stretched area of the net body. It is 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, in this embodiment, three ropes 26 are bridged between both ends of the valley R in the width direction. The rope 26 and the ring net 18 are engaged. As the rope 26, for example, a high-strength wire rope or the like is applied. The wire diameter of the rope 26 is, for example, about 12 to 30 mm. The three ropes 26 are disposed at predetermined intervals below the height with the above-mentioned predetermined height being the uppermost position, and each of the ropes 26 is placed inside the ring of the ring-shaped member 20 of the ring net 18, for example. And is engaged by being inserted through. Therefore, the engagement height position between the uppermost rope 26 and the ring net 18 is the upper end of the ring net 18.

  It is desirable that the ring-shaped member 20 and the rope 26 be connected at the portion where the rope 26 is inserted. Further, the rope 26 may be locked to the ring-shaped member 20 using, for example, an individual locking tool called a shank or a jaw without passing through the ring member of the ring net 18. Further, the rope 26 at the upper end of the net body stretching area supports, for example, the ring-type net 18 so as to be suspended, but all the ropes 26 including the rope 26 at the upper end are simply ring-type. In addition to supporting the net 18, the ring-type net 18 has a function of reinforcing the ring-type net 18 when the flow-down material is blocked. That is, the kinetic energy of the falling object when the debris flow occurs is absorbed by the deformation of the ring net 18 but is also transmitted to the rope 26. With respect to the kinetic energy transmitted to the rope 26, the rope 26 is firmly fixed to the ground H, or a braking force is applied to the rope 26 while allowing the rope 26 to extend. , The ring net 18 can be reinforced.

  Further, in this embodiment, the three ropes 26 are configured such that the slack of the lower ropes 26 in the height direction is greater than the slack of the upper ropes 26 as is apparent from the drawing. As described later, this is for the purpose of increasing the volume of the flow-down material accommodated by the ring-type net 18 and the rope 26 when the ring-type net 18 that blocks the flow-down material is deformed, that is, the capacity of the pocket as it goes downward. . Further, in this embodiment, the lower the rope 26, the larger the allowable elongation between the fixed portions at both ends of the rope 26 by the brake device 30 described later. This is also for the purpose of increasing the flow-through material storage volume by the ring net 18 and the rope 26, that is, the volume of the pocket downward.

  Both ends of each of the ropes 26 are fixed to the ground H on both sides in the width direction of the valley R by the fixing means 2, respectively. For example, as shown in FIG. 2, these fixing means 2 include an anchor 3 cast on the surface of the ground H, a pressure receiving plate 4 through which the anchor 3 is inserted and fixed, and which is in contact with the surface of the ground H. A connecting means 5 for connecting the pressure receiving plate 4 to the end of the rope 26 is provided. The pressure receiving plate 4 is made of a thick plate made of, for example, metal, concrete, or plastic. For example, a cross shape as shown in the figure, a fin-like thin plate connected between the crosses, and other various shapes are available. Things already exist. The size of the pressure receiving plate 4 is, for example, about 1 to 3 m when crossed. As the connecting means 5, for example, a turnbuckle member was used. 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. Then, these eyebolts 6 and the ends of the rope 26 are connected by connecting means 5 such as a turnbuckle member. A wire rope or the like can be applied to the connecting means 5.

  The anchor 3 of this embodiment is made of, for example, a steel bar, and the cement milk 8 inserted into the anchor hole 7 drilled from the surface of the ground H to the stabilized formation D and injected into the anchor hole 7 is used. It is hardened and fixed to the ground H. The diameter of the anchor hole 7 is about 120 mm, the diameter of the anchor 3 is about 50 mm, and the depth of the anchor hole 7 is about 7 to 30 m. As is well known, in the ground H on the steep slope, there is a possibility that the unstable layer T in the surface layer slides down on the slip surface indicated by the broken line in the figure. Therefore, in general, the anchor 3 is placed so as to reach the deeper stabilized formation D from the slip surface. That is, if the cement milk 8 hardens in the anchor hole 7 reaching the stabilized formation D of the ground H, the anchor 3 is integrated with the stabilized formation D.

  In this embodiment, a male screw is formed in the pressure receiving plate penetrating projecting portion of the anchor 3. After the anchor 3 is inserted into the through hole of the pressure receiving plate 4, for example, a cap nut 9 with a seat is screwed into the male screw. The pressure receiving plate 4 is pressed against the surface of the ground H by tightening, whereby the anchor 3 is inserted and fixed to the pressure receiving plate 4. Therefore, the pressure receiving plate 4 that contacts 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. A cap, for example, as shown by a dashed line in the figure is mounted on the pressure receiving plate penetrating projection of the anchor 3 and the cap nut 9, and grease for rust prevention is sealed in the inside. Further, a liquid absorbing cushion may be interposed between the pressure receiving plate 4 and the surface of the ground H, and cement milk may be injected and solidified into the cushion. Further, in place of the steel rod anchor, an existing anchor method using a plurality of strands of PC steel may be used.

  In addition, when the ring-shaped member 20 receives the falling material and deforms the ring-shaped member 20, the entire ring-type net 18 swells downstream. At this time, the lower end of the ring-type net 18 bulging downstream is turned up, so that the falling material does not flow out from the lower side of the ring-type net 18 to the downstream side. Then, the ring-shaped member 20 at the upstream end thereof 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 by its own weight or the weight of the ring net 18 as shown in FIG. The amount of slack makes it possible to adjust the suppression of the falling object by the ring net 18 and the suppression of the falling object by the rope 26 engaged with the ring net 18. That is, since the rope 26 is engaged with the ring-shaped member 20 of the ring net 18, the movement of the rope 26 and the movement of the ring net 18 at the time of occurrence of debris flow are linked to each other.

  The kinetic energy absorbing effect of the debris flow due to the deformation of the ring-type net 18, which will be described in detail later, is exerted when the net is no longer bent and the ring-shaped member 20 is deformed. On the other hand, the falling material is received by the ring net 18 and the slack of the rope is eliminated by the ring net 18 swelling to the downstream side. Can be supported. At this time, if a braking force is applied to the rope 26 while allowing the rope 26 to extend, the kinetic energy of the debris flow can be absorbed by the extension of the rope 26 accompanied by the braking force. Therefore, a brake device 30 is provided at both ends of the rope 26 to allow the length of the length between the two fixed portions of the rope to increase with a predetermined braking force. In this embodiment, as described above, the allowable elongation of the length between the two fixed portions of the rope 26 by the brake device 30 is set to be larger for the lower rope 26.

  The brake device 30 regulates, for example, the movement of the rope 26 in the longitudinal direction during normal times. When the debris flow occurs, the tension of the rope 26 increases when the ring net 18 receives the falling material and swells downstream to eliminate the slack of the rope 26. If the tension is larger than the regulating force of the rope 26 by the brake device 30, for example, the rope 26 slides in the brake device 30, and the frictional resistance associated with the slip becomes a braking force, and the kinetic energy of the debris flow is reduced by the braking force. Absorbed.

  In this embodiment, the amount of elongation of the rope 26 by these brake devices 30 is adjusted so that the elongation of the length between the two fixed portions of the rope 26 is limited at the same time as or before the deformation limit of the ring net 18. Set. With this configuration, the deformation limit of the ring net 18 is at or after the limit of the length extension between the two fixed portions of the rope 26, so that the kinetic energy absorption of the debris flow due to the extension of the rope 26 with the braking force. The kinetic energy of the debris flow exceeding the amount can be absorbed by the deformation of the ring net 18.

  For example, if the limit of the elongation of the rope 26 accompanying 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 a kinetic energy exceeding this limit, the rope 26 is completely extended. After the deformation, the kinetic energy exceeding the upper limit value can be absorbed by the deformation of the ring-type net 18, and thus the falling material can be suppressed. In addition, when the debris flow occurs, if the ring-type net 18 is not at the deformation limit, the rope 26 can be replaced and the ring-type net 18 can be reused as it is. Become.

  In the case where a plurality of brake devices 30 are provided for one rope 26 as shown in FIG. 1, for example, the magnitudes of the braking forces of the brake devices 30 may be set to different values. . With such a distribution of the braking force, for example, when two brake devices 30 are provided on one rope 26, one of the brake devices 30 operates first to exert a braking force, and thereafter, the other brake device 30 exerts the braking force. The brake device 30 of FIG. This makes it possible to exert the braking force continuously or intermittently, that is, to continuously absorb the kinetic energy while the rope 26 supporting the falling object continues to elongate.

  Next, the ring net 18 used in the present embodiment will be described. This ring-type net 18 is the same as that described in, for example, JP-A-2014-1584 (hereinafter also referred to as a prior art document), and is configured by connecting a plurality of ring-shaped members 20 to each other. In this embodiment, for example, as understood from FIG. 1, the four ring-shaped members 20 are evenly arranged around one ring-shaped member 20 so that It connects so that peripheral sides may contact. The connection structure of the ring-shaped member 20 has various forms as described in the prior art document.

  FIG. 3 is a perspective view showing an example of a ring-shaped member 20 used for the ring net 18 of FIG. This ring-shaped member 20 is configured by winding a wire 22 made of, for example, a steel wire a plurality of times (5 to 20 times) and fastening several places in a circumferential direction by fasteners 24. The fastener 24 is, for example, a substantially cylindrical metal member having a C-shaped side surface, and is fixed by being swaged after covering over the outside of the wire 22 that has been superposed by winding. This ring-shaped member 20 is also the same as that described in the above-mentioned prior art document, for example, the material of the wire 22, the wire diameter of the wire 22, the number of turns of the wire 22, the crimping force by the fastener 24, and the like. By adjusting, it is possible to adjust the strength at deformation and the energy absorbing power described later.

The wire 22 constituting the ring-shaped member 20 is preferably a steel wire manufactured from a hard steel wire, for example, but may be an iron wire manufactured from a mild steel wire, for example. In the case of a steel wire, a wire having a tensile strength of 800 N / mm ² or more is preferable. Further, those obtained by plating or coating these wires 22 can also be used. The diameter of the wire 22 is about 2.5 to 5 mm, and the diameter of the ring-shaped member 20 is about 300 to 1500 mm. By changing the diameter of the ring-shaped member 20, the ring-type net 18 can easily cope with the size of the flow-down material (boulder) to be blocked. For example, if the size of the boulder on the upstream side is investigated and the diameter of the ring-shaped member 20 is set in accordance with the size, it is possible to effectively block the falling material when the debris flow occurs.

  In the ring-type net 18 formed by connecting the ring-shaped members 20, for example, when a force (load) perpendicular to the net surface is applied, the ring-shaped members 20 are pulled together, so that the shape itself of the ring-shaped member 20 is deformed. At the same time, the wire 22 constituting the ring-shaped member 20 is deformed so that the winding thereof is loosened. These deformations occur when the kinetic energy of the debris flow, specifically, boulders and driftwood collide and a load acts on the net surface, and when a load is applied to the ring net 18, the ring-shaped member 20 is deformed. As a result, the kinetic energy of the debris flow is absorbed, and as a result, the effect of blocking boulders and driftwood is obtained by the entire ring net 18. Since the debris flow is generated from the upstream side to the downstream side of the mountain stream, the ring net 18 in which the ring-shaped member 20 is deformed by the kinetic energy of the debris flow bulges downstream when receiving the debris flow, as described above. .

  From these facts, it can be said that the sabo dam using the ring-type net 18 has a "soft structure" that receives the kinetic energy of the debris flow due to the deformation of the ring-shaped member 20, but only the conventional concrete dam type sabo dam and the middle basin part. This is different from the “rigid structure” of a transmission type sabo dam with a ridge. In the case of this embodiment, if the movement of the falling object can be suppressed by the entire ring net 18 including the rope 26 and the brake device 30 described above, thereafter, the rope 26 and the ring net 18 are tied up. The load received by the fixing means 2 is the static load of the falling object. As is well known, the same object has a much smaller static load than a dynamic load. Therefore, even if it has a simple structure, the fixing means 2 can continue to support the ring-type net 18 and the rope 26 that block the falling material, and thus do not need a foundation / framework made of a so-called concrete structure. . Therefore, the sabo dam can be constructed even in the valley R where it is difficult to construct the concrete structure, and the construction is greatly facilitated. This ease of construction brings great advantages in the place where the dam is built, that is, in the mountains.

  FIG. 4 is a partial cross-sectional side view showing a state in which the falling material is blocked by the sabo dam 1 of FIG. As described above, the ring-type net 18 that blocks the flow-down material swells downstream as the ring-shaped member 20 deforms (extends). In this embodiment, of 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 equal to the upper rope 26. Is set to be larger than the allowable elongation, the falling material storage volume constituted by the ring-type net 18 and the rope 26 that deforms so as to swell to the downstream side, that is, the volume of the pocket that receives the falling material is the height. Larger downward in the direction. Therefore, a large amount of the falling-down material is stably accommodated in the large pocket below, so that a large amount of the falling-down material can be stably captured. In addition, since the pressure receiving plate 4 for fixing the rope 26 to the ground H is pressed to cover the surface of the ground H, the valley shore portion, which contributes to the huge debris flow, that is, the ground H The collapse of the surface can be suppressed, thereby making it possible to prevent the debris flow from becoming huge. In addition, it is possible to increase the flow-down material storage volume as it goes downward in the height direction by only one of the setting of the slack of the rope 26 and the setting of the allowable elongation.

  As described above, according to the sabo dam of the present embodiment, the ring net 18 is engaged with the rope 26 whose both ends are fixed to the ground H, so that the ring net 18 is substantially in the width direction of the valley R. When the debris flow occurs, the falling flow of boulders and driftwood flowing through the valley R is blocked by the ring net 18 when the debris flow occurs. At this time, the kinetic energy of the debris flow is absorbed by the deformation performance of the ring net 18. By doing so, it is possible to block the falling material with the entire ring net 18. Therefore, a giant concrete structure is not required, and for example, it becomes possible to construct a dam at a small valley R near a mountaintop or a deep mountain. Further, since the pressure receiving plate 4 for fixing the rope 26 to the surface of the ground H not only receives the reaction force of the force related to the anchor 3 but also covers the surface of the ground H so as to press the surface, the debris flow It is possible to suppress the collapse of the ground surface, which is one of the causes of enormous enlargement, to protect the ground surface, and to suppress the giant debris flow.

  In addition, the lower rope 26 in the height direction is set to have a larger slack than the upper rope 26, so that the downflow constituted by the ring-type net 18 and the rope 26 deformed due to the catching of the falling object when the debris flow occurs. Since the material storage volume becomes larger downward in the height direction, it is possible to stably capture a large amount of the flowing-down material.

  In addition, the lower the rope 26 in the height direction, the larger the allowable elongation of the length between the fixed portions at both ends than the upper rope 26, the deformation of the ring-type net 18 that catches the falling material when the debris flow occurs. Of the rope 26 associated with the rope 26, the greater the lower the rope 26 in the height direction, the larger the volume of the falling material formed by the deformed ring-type net 18 and the elongated rope 26 becomes, the lower the height of the rope 26 becomes. An object can be stably captured in a larger amount.

  In addition, by fixing the lower end of the ring net 18 to the bottom B of the valley R, the lower end of the ring net 18 that blocks the falling objects such as boulders and driftwood during the debris flow is prevented from turning up. Therefore, it is possible to prevent the falling material at the time of generation of the debris flow from flowing from below the ring-type net 18 to the downstream, and it is possible to reliably block them with the ring-type net 18.

  In addition, a large load is applied to the rope 26 by providing the rope 26 with a brake device 30 that allows the length of the rope 26 to elongate with a predetermined braking force when a load equal to or more than a predetermined value is applied. Since the elongation of the rope 26 is sometimes permitted with a predetermined braking force, it is possible to secure a braking action, that is, a kinetic energy absorbing force with the elongation of the rope 26. This makes it possible to more accurately absorb the kinetic energy of a falling material such as a debris flow, and the falling material can be more reliably blocked by the entire ring net 18 including the rope 26.

  Although the embodiments have been described above, the configuration of the present invention is not limited to these embodiments, and various modifications can be made within the scope of the invention. For example, the number and material of the above-described ropes 26 are appropriately selected according to the situation at the site, and the brake devices are not limited to the above-described configuration, but may be applied while applying a braking force. Any material may be used as long as it allows the rope 26 to extend.

  Further, in the above-described embodiment, the ring-type net 18 is stretched by one stretch between the grounds H. However, a plurality of ring-type nets 18 may be stretched and stretched between the grounds H.

  Further, instead of the ring-type net 18, another net body can be applied. As such a net body, for example, as shown in FIG. 5, a rhombic wire net 26 made of a metal wire having a rhombic mesh can be used as the net body. As described in, for example, Japanese Patent Application Laid-Open No. 2016-37773, the rhombic wire mesh 26 is formed by, for example, bending a metal wire 28 to form a triangular-wave wire, and forming peaks and valleys of a plurality of triangular-wave wires arranged in parallel. It is constructed by weaving each other and engaging these triangular-shaped wires. Mild steel, hard steel, spring steel, stainless steel, or the like can be used for the metal wire 28 constituting the triangular-wave shaped wire. If necessary, the metal wire 28 may be coated to prevent abrasion, corrosion, and the like of the contact portion of the triangular wire. Examples of the coating treatment include a galvanizing treatment and a polyester coating treatment. Any net body including the rhombic wire net 26 can be used for the net body of the present invention, as long as it can block downflows.

2 Fixing means 3 Anchor 4 Pressure plate 5 Connecting means 7 Anchor hole 8 Cement milk 18 Ring net (net body)
Reference Signs List 20 ring-shaped member 26 rope 30 brake device 38 anchor pin H ground mountain R valley B bottom D stabilized stratum

Claims (5)

A sabo dam built in a valley sandwiched between grounds,
A rope that is bridged between both ends in the width direction of the valley, and both ends are fixed to the ground respectively;
By being engaged with the rope, a net body extended to a region from the bottom of the valley to a predetermined height position and stretched in a substantially width direction of the valley,
Fixing means for fixing both ends of the rope to the ground,
The fixing means,
An anchor cast on the surface of the ground,
A pressure receiving plate through which the anchor is inserted and fixed, and which comes into contact with the surface of the ground;
A sabo dam comprising: a connecting means for connecting the pressure receiving plate or anchor to an end of the rope. A plurality of the ropes are arranged in a height direction of the valley,
The sabo dam according to claim 1, wherein the lower the rope in the height direction, the larger the slack is set than the upper rope. A plurality of the ropes are arranged in a 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 allowable 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 of the net body is fixed to a bottom of the valley.   5. A rope device according to claim 1, wherein said rope is provided with a brake device which permits extension of the length of said rope while applying a predetermined braking force when a load equal to or more than a predetermined value is applied. Or the sabo dam according to item 1.

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