Disaster prevention structure

Abstract

To reduce bending moment generated in horizontal members installed between neighboring pillar members, when constructing a sand control dam to dam up debris flows and the like in mountain streams and the like where debris flows and the like are expected to occur.SOLUTION: A disaster prevention structure 1 is constructed of a plurality of column members 2, 2 arranged at intervals in either direction of a construction object, and a plurality of horizontal members 3 made of steel pipe concrete erected at intervals in a height direction between neighboring column members 2, 2. An inclined surface 3a which is inclined in a direction in which an axial length of the horizontal member 3 gradually increases from a downstream side to an upstream side with respect to a plane perpendicular to an axial direction of the horizontal member 3 is formed on both axial end faces of the horizontal member 3. A support surface 2a of the column member 2 that receives the inclined surface 3a is provided with an inclined surface corresponding to the inclined surface 3a of the horizontal member 3. The horizontal member 3 is supported by the column member 2 while the inclined surface 3a is in surface contact with the support surface 2a of the column member 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to disaster prevention structures such as sabo dams constructed for the purpose of damming up debris flows, etc., that may occur, for example, in mountain streams and other construction targets where debris flows, driftwood, etc. may occur. [Background technology]

[0002] For example, a buttress-type sabo dam constructed for the purpose of damming up debris flows in mountain streams etc. requires only horizontal members to be erected between adjacent buttresses in the width direction of the mountain stream. As a result, the structure is relatively simple, and the dam has the advantage that the impact (kinetic energy) generated when debris or rocks are received can be transmitted through the buttress to the riverbed or foundation concrete etc. (see Patent Documents 1 to 3).

[0003] However, when a horizontal member (top slab) is constructed on a buttress and joined to an adjacent buttress as in Patent Document 1, the horizontal member becomes a beam fixed at both ends, so when it receives a concentrated load from soil or rocks, it will bear the bending moment that is greatest at the center and both ends in the axial direction.

[0004] When a horizontal member is installed between adjacent buttresses and connected to the buttresses by a fitting means as in Patent Documents 2 and 3, the horizontal member becomes a simple beam, and therefore bears the bending moment that is greatest at the center in the axial direction in response to a concentrated load.

[0005] In addition, there is a method in which two horizontal members are connected by using a sheath pipe that spans between the ends of the horizontal members that are divided into two in the axial direction and joined at one end to a bracing member equivalent to a buttress (see Patent Documents 4 and 5). In these examples, the horizontal member becomes a cantilever beam with the other end that the sheath pipe spans as the free end, so the bending moment generated at one end of the horizontal member becomes maximum. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-180441 A (paragraphs 0022-0028, 0041-0044, Figs. 1 and 4) [Patent Document 2] JP 2005-336802 A (paragraphs 0018 to 0037, Figures 1 to 6) [Patent Document 3] JP 2010-84455 A (paragraphs 0025 to 0040, Figures 1 to 8) [Patent Document 4] JP 2013-204272 A (Claim 3, paragraphs 0029 to 0051, Figures 1 to 5) [Patent Document 5] JP 2021-156123 A (Claim 1, paragraphs 0023 to 0032, Figures 1, 4, and 5) Summary of the Invention [Problem to be solved by the invention]

[0007] In both examples, the reaction force from the impact force (concentrated load) from the soil and rocks acts on the horizontal members only in a direction perpendicular to the axis of the members, so the horizontal members must have cross-sectional performance sufficient to withstand the maximum bending moment corresponding to the expected impact force.

[0008] In view of the above background, the present invention proposes a disaster prevention structure that uses horizontal members having a structure that can reduce the bending moment that occurs in the horizontal members installed between adjacent column members such as buttresses. [Means for solving the problem]

[0009] The disaster prevention structure of the invention described in claim 1 comprises a plurality of pillar members arranged at intervals in any direction of a construction target, and a plurality of horizontal members made of reinforced concrete installed at intervals in the height direction between the pillar members adjacent in the said direction, The end faces on both sides of the horizontal member in the axial direction have inclined surfaces that are inclined with respect to a plane perpendicular to the axial direction of the horizontal member such that the axial length of the horizontal member gradually increases from the downstream side to the upstream side of the construction target, and the support surface of the column member that receives the inclined surface of the horizontal member has an inclined surface that corresponds to the inclined surface of the horizontal member, A constituent element of the present invention is that the horizontal member is supported by the pillar member while being in surface contact with the support surface of the pillar member at the inclined surface.

[0010] Disaster prevention structures refer to structures in general that serve to catch "moving objects" that cause disasters, such as the aforementioned sabo dams and driftwood capture structures, as well as rockfall and avalanche prevention fences. "Column members" refer to buttresses and bracing members when the disaster prevention structure is an sabo dam, as well as components of the disaster prevention structure that support horizontal members. In cases other than buttresses, column members are not necessarily vertical members whose axial direction faces the vertical direction, and the axial direction may face in an inclined direction relative to the vertical direction. "Moving objects" refer to objects that cause disasters such as debris flows, driftwood, falling rocks, and landslides. In the following, "moving objects" are referred to as "debris flows, etc."

[0011] "Construction target" refers to the location where the disaster prevention structure is constructed, which is the mountain stream in the case of erosion control dams and driftwood capture works, and the slope or similar location in the case of rockfall / avalanche prevention fences, etc. "Any direction of the construction target" refers to any one direction of the construction target, which is the width direction of the mountain stream in the case of erosion control dams, etc., and the horizontal direction along the slope in the case of rockfall prevention fences, etc.

[0012] "The end faces on both sides of the horizontal member in the axial direction have inclined surfaces that are inclined with respect to a plane perpendicular to the axial direction of the horizontal member" means that, as shown in Figure 5, at least a part of the end faces on both sides of the axial direction of the horizontal member 3 has inclined surfaces 3a that form an angle with the plane perpendicular to the axial direction of the horizontal member 3. "Horizontal members" are not necessarily erected with their axial direction facing perfectly horizontally, and they may be erected with their axial direction inclined with respect to the horizontal direction.

[0013] The "axial direction of the horizontal member (axis direction)" can be any direction of the construction object, such as the width direction of the stream when the horizontal member is installed (in use). The "plane perpendicular to the axial direction of the horizontal member" refers to the end face of a normal reinforced concrete horizontal member (beam member) with no inclination on the end face, and refers to a plane parallel to the direction of the flow of a debris flow, such as the direction of a stream when the horizontal member is installed. The end face of the horizontal member 3 is basically flat, but the entire end face does not necessarily have to be flat, and may include a curved or uneven surface in part. "At least a part of the end face" means that part of the end face may include a surface other than a flat surface.

[0014] "The horizontal member is inclined in such a direction that its axial length gradually increases from the downstream side to the upstream side of the construction target" means that when the horizontal member 3 in the erected state is viewed in a plane (plan view) as shown in Figure 5, the axial length of the horizontal member 3 is inclined in such a direction that it gradually increases from the downstream side (lower side of the figure) to the upstream side (upper side of the figure) of the construction target. When the construction target is a slope, etc., the "downstream side" and the "upstream side" are the lower side and the upper side, respectively. The "inclined surface 3a" is basically a vertical surface, but it does not necessarily have to be a vertical surface, and it may be a surface that is inclined with respect to the vertical direction, or a surface that includes a curved surface. The "flow direction of debris flow, etc." above is "from the upstream side to the downstream side."

[0015] "Having an inclined surface 3a" means that when the horizontal member 3 is viewed in the direction of action of the impact force (load) due to a debris flow or the like, the entire end face of the horizontal member 3 does not necessarily have a uniform inclined surface 3a. FIG. 5 shows an example in which the entire end face of the horizontal member 3 is formed as a uniform inclined surface 3a, but the inclined surface 3a may be formed only in the section from the downstream side to partway up the upstream side as shown in FIG. 6-(a) and (b), or only in the section from the upstream side to partway down the downstream side as shown in (c). In the example shown in FIG. 6, the axial length of a part of the upstream side or a part of the downstream side when the horizontal member 3 is viewed in the direction of action of the impact force is constant, and that part has an end shape that does not have an inclined surface 3a.

[0016] The statement that "the supporting surface of the column member that receives the inclined surface of the horizontal member has an inclined surface corresponding to the inclined surface of the horizontal member" means that the supporting surface 2a of the column member 2 that supports the inclined surface 3a of the horizontal member 3 in the acting direction of a debris flow or the like is substantially parallel to the inclined surface 3a of the horizontal member 3 and has an inclined surface capable of making surface contact with the inclined surface 3a. The statement "receives the inclined surface" means that the supporting surface 2a of the column member 2 supports the inclined surface 3a of the horizontal member 3 in the acting direction of a debris flow or the like.

[0017] "Surface contact" does not necessarily mean that the inclined surface 3a of the horizontal member 3 and the supporting surface 2a of the column member 2 must be in complete surface contact. It is sufficient if they are in a surface contact state as a whole. Although the supporting surface 2a of this column member 2 is basically a plane, it does not necessarily have to be a plane. The inclined surfaces 3a on both sides in the axial direction of the horizontal member 3 are in surface contact with the supporting surfaces 2a of the column members 2 on their respective sides and are supported in the acting direction of a debris flow or the like.

[0018] The statement that "the horizontal member 3 is supported by the column member 2 while making surface contact with the supporting surface 2a of the column member 2 at the inclined surface 3a" means that the horizontal member 3 is supported vertically downward by the column member 2 in a state where the inclined surface 3a of the horizontal member 3 is in surface contact with the supporting surface 2a of the column member 2 in the acting direction of a debris flow or the like. The horizontal member 3 is supported by the column member 2 by being placed on the "placement surface 2b" of the column member 2 described later.

[0019] Basically, the inclined surface 3a of the horizontal member 3 and the supporting surface (inclined surface) 2a of the column member 2 simply come into contact with each other, but depending on the design concept, they may be joined to each other. When the contact surfaces are joined, a bending moment is generated at the end of the horizontal member 3, but when they only come into contact, no bending moment is generated at the end of the horizontal member 3. As will be described later, only a bending moment and a shear force caused by the reaction force F2 (<W) received from the supporting surface 2a of the column member 2 are generated along the axial direction of the horizontal member 3. Even when the contact surfaces are joined, as will be described later, the component F2 of the reaction force that causes the bending moment and the shear force and is orthogonal to the axial direction is smaller than the case where the inclined surface 3a is not provided, so the bending moment and the shear force are also smaller.

[0020] The end faces on both axial sides of the horizontal member 3 have inclined surfaces 3a inclined with respect to a plane perpendicular to the axial direction, the support surface 2a of the column member 2 corresponds to the inclined surface 3a of the end face of the horizontal member 3, and has an inclined surface capable of surface contact with the inclined surface 3a. Thus, when the horizontal member 3 receives an impact force 2W due to a debris flow or the like as shown in FIG. 5, a force of W acts from each inclined surface 3a of the horizontal member 3 on each support surface 2a of the column member 2.

[0021] Assuming that the inclined surface 3a and the support surface 2a are in complete surface contact, the inclined surface 3a of the horizontal member 3 receives a force P perpendicular to the support surface 2a from the support surface 2a as a reaction force of W acting on the support surface 2a of the column member 2. If the angle formed by the axial direction of the horizontal member 3 and the inclined surface 3a is θ, then P = Wcosθ. The component F1 parallel to the axial direction of the horizontal member 3 is F1 = Wcosθ·sinθ (= W / 2·sin2θ), and the component F2 perpendicular to the axial direction of the horizontal member 3 is F2 = Wcosθ·cosθ = W(cosθ) 2 is divided into.

[0022] In Patent Documents 1 to 5, θ = 0°, so sinθ = 0 and cosθ = 1, and thus F1 = 0 and F2 = W. In contrast, in the present invention, since 0 < θ < 90°, F1 > 0 and 0 < F2 < W. A reaction force F2 smaller than W in the direction perpendicular to the axial direction and an axial force F1 act on the horizontal member 3.

[0023] Since the axial force F1 acts on both inclined surfaces 3a, 3a of the horizontal member 3 toward the axial center, it is an axial compressive force. Also, if 0 < θ < 90°, then F2 < W. Therefore, the reaction force in the direction perpendicular to the axial direction is smaller than the impact force W due to a debris flow or the like compared to the case where the inclined surface 3a is not present on the end face of the horizontal member 3, and the bending moment and shear force become smaller.

[0024] For example, when θ = 45°, cosθ = sinθ = 1 / √2, so F1 = F2 = W / 2. From F1 / F2 = sinθ / cosθ, if θ < 45°, then F1 < F2, and if θ > 45°, then F1 > F2. Incidentally, since F1 = W / 2·sin2θ, F1 is maximum when θ = 45°.

[0025] In other words, by forming the inclined surface 3a on the end face of the horizontal member 3, the horizontal member 3 can receive the reaction force F1 from the column member 2 as an axial compression force, while at the same time reducing the bending moment and shear force (stress) distributed in the axial direction. In particular, in order to reduce the reaction force F2 in the direction perpendicular to the axial direction of the horizontal member 3, it is desirable for 45°<θ<90°, and in order to maximize the axial force F1, it is desirable for θ=45°.

[0026] By forming an inclined surface 3a on the end face of the horizontal member 3, the horizontal member 3 itself receives axial compression force while reducing the stress (bending moment and shear force) distributed in the axial direction, so the horizontal member 3 is made of reinforced concrete with high compressive strength, and in particular steel pipe concrete (concrete-filled steel pipe (CFT)) which has high compressive strength. In the latter case, the steel pipe 31 includes circular steel pipes and square steel pipes. In some cases, tensile members made of materials that can introduce tensile force, such as reinforcing bars (main bars), PC steel, fiber reinforced plastics, etc., are placed along the axial direction in the concrete 32.

[0027] The horizontal member 3 is supported in the direction of action of a debris flow, etc., by the support surfaces 2a, 2a of the pillar members 2 on each side at the inclined surfaces 3a, 3a on both axial sides. On the other hand, in order for the horizontal member 3 to be supported vertically downward in the erected state between the pillar members 2, 2, it is necessary that a recess 21 is formed in the surface, etc., on the upstream side of the pillar member 2 as shown in Figures 7 and 8 (Claim 2).

[0028] When viewed in the direction of action of the debris flow, etc., the downstream side of this recess 21 becomes a support surface 2a that supports the horizontal member 3 in the flow direction of the debris flow, etc., and below and above the support surface 2a, a placement surface 2b and a holding surface 2c that can sandwich and hold the horizontal member 3 from above and below are respectively formed on the inner peripheral surface of the recess 21 (Claim 2). The "downstream side of the recess 21" refers to the farthest surface when the recess 21 is viewed in the direction of the flow of the debris flow, etc. (from upstream to downstream).

[0029] The ends of the horizontal member 3 on both axial sides are in contact with the support surface 2a of the pillar member 2 on the inclined surface 3a in the direction of flow (the action of impact force) of a debris flow or the like, while being sandwiched from above and below between the placement surface 2b and the holding surface 2c (Claim 2). "The end of the horizontal member 3 is sandwiched from above and below between the placement surface 2b and the holding surface 2c" means that while the lower surface of the end of the horizontal member 3 is in contact with the placement surface 2b, there are cases where the upper surface does not contact the holding surface 2c.

[0030] In any direction of the construction object (such as the width direction of the stream), the recesses 21 are formed on the side where the horizontal member 3 is installed, so there are some parts where they are formed on both sides of the center of the pillar member 2, and some parts where they are formed on only one side. "Any direction of the construction object (such as the width direction of the stream)" refers to the thickness direction of the pillar member 2 when the pillar member 2 is a buttress.

[0031] Since the horizontal member 3 is installed between adjacent pillar members 2, 2, in a portion where the pillar member 2 is located on one side in any direction of the construction target, such as the width direction of the stream, the recess 21 is formed only on one side of the center. In a portion where the pillar member 2 is located in the middle of any direction of the construction target (such as the width direction of the stream), the horizontal members 3 are installed on both sides of the pillar member 2, so recesses 21, 21 are formed on both sides of the center, as shown in Figures 7 and 8.

[0032] For the horizontal member 3 to be supported downward by the pillar member 2, it is sufficient that the horizontal member 3 is placed on the placement surface 2b of the recess 21, and it can be said that it does not necessarily have to be held by the retaining surface 2c. However, when subjected to an impact force from a mudslide or the like, if there is no retaining surface 2c, the horizontal member 3 will be likely to float up and it may be difficult for it to remain in the recess 21. Therefore, depending on the expected level of impact force, it is often necessary to form the retaining surface 2c in order for the horizontal member 3 to withstand the impact.

[0033] In claim 2, a recess 21 is formed from the upstream side of the pillar member 2, and both axial ends of the horizontal member 3 are contained within the recess 21.Therefore, the horizontal member 3 is in contact with the support surface 2a at the inclined surface 3a while also being constrained in the vertical direction within the recess 21, and the weight of the horizontal member 3 is supported by the bottom surface (support surface 2b) within the recess 21, while at the same time being constrained against vertical upward movement at the holding surface 2c.

[0034] In particular, if a restraining portion 2d for preventing the horizontal member 3 from falling out of the recess 21 is formed on the surface of the upstream side of the horizontal member 3, that is, the column member 2, when the end of the horizontal member 3 is fitted in the recess 21 (claim 3), the end of the horizontal member 3 fits in the recess 21, and while the inclined surface 3a is in surface contact with the support surface 2a, stability against falling out of the recess 21 is ensured in a state supported by the column member 2. The restraining portion 2d may be formed as a part of the column member 2 as shown in Figs. 7 and 9, or may be combined as a separate restraining member 2e that can be freely attached and detached as shown in Fig. 8. In claim 3, "the restraining portion 2d is arranged" means that the restraining member 2e as the restraining portion 2d is arranged.

[0035] The horizontal member 3 is basically installed between adjacent pillar members 2, 2 by moving parallel to the upstream side of the pillar member 2, or by inserting one end of the horizontal member 3 in the axial direction into the recess 21 of the pillar member 2 on that side and then rotating the other end of the horizontal member 3 in the horizontal direction around the one end of the horizontal member 3. In this relationship, when the restraining portion 2d formed on the surface side of the recess 21 of one of the adjacent pillar members 2, 2 is part of the pillar member 2, in principle the other restraining portion 2d (restraining member 2e) is formed as a separate body.

[0036] However, if there is enough space to allow one end of the horizontal member 3 to move in the axial direction of the horizontal member 3 within the recess 21 on that side, there is no need to rotate the other end, and therefore it is not necessarily necessary for the other restraint portion 2d to be formed as a separate body.

[0037] In either case, if the cross-sectional shape of the horizontal member 3 is circular, or if the steel pipe 31 in the case of steel pipe concrete is a circular steel pipe, the end of the horizontal member 3, which fits within the recess 21 and is supported in the direction of action of the debris flow, etc., is prevented from falling out of the recess 21 due to some force toward the upstream side, such as a reaction force of an impact force, or by rotating around its axis, and therefore the function of the horizontal member 3 to block debris flows, etc. is maintained.

[0038] If the cross-sectional shape of the horizontal member 3 is square, or if the steel pipe 31 in the case of steel pipe concrete is a square steel pipe, the horizontal member 3 is less likely to rotate around its axis, and is therefore less likely to fall out of the recess 21 than in the case of a circular steel pipe. However, if a restraint portion 2d is formed upstream of the recess 21 (claim 3), the horizontal member 3 will be reliably prevented from falling out of the recess 21 even if it is subjected to a force toward the upstream side. Effect of the Invention

[0039] On both axial end faces of a reinforced concrete horizontal member that is erected between adjacent column members in either direction of the object to be constructed, an inclined surface is formed that is inclined with respect to a plane perpendicular to the axial direction of the horizontal member in a direction in which the axial length of the horizontal member gradually increases from the downstream side to the upstream side of the object to be constructed, and an inclined surface corresponding to the inclined surface of the horizontal member is formed on the support surface of the column member that receives the inclined surface of the horizontal member, so that the horizontal member can receive the reaction force from the column member in a direction perpendicular to the inclined surface of the impact force from a debris flow, etc. As a result, the horizontal member can receive the reaction force from the column member as an axial compression force, while at the same time reducing the bending moment and shear force distributed in the axial direction. [Brief description of the drawings]

[0040] [Figure 1] This is an oblique view showing the upstream side of a horizontal member installed between column members when the cross-sectional shape of the horizontal member is circular or when a circular steel pipe is used as the steel pipe in the case of steel pipe concrete. [Diagram 2] FIG. 2 is a perspective view showing the downstream side of FIG. 1. [Diagram 3] FIG. 2 is an enlarged view of FIG. [Figure 4] 3, and (b) is a cross-sectional view taken along line xx in (a). [Diagram 5] This is an explanatory plan view showing the reaction forces that each inclined surface receives from each support surface when a horizontal member receives an impact force 2W from a mudslide or the like, and a force of W acts from each inclined surface of the horizontal member to each support surface of the pillar member. [Figure 6] 1A and 1B are plan views showing the relationship between the horizontal member and the supporting surface of the column member when the inclined surface of the horizontal member is formed halfway from the downstream side to the upstream side, and 1C is a plan view showing the relationship between the horizontal member and the supporting surface when the inclined surface is formed halfway from the upstream side to the downstream side. [Figure 7] 1A is a horizontal cross-sectional view showing the horizontal member stored in the recesses on both sides of adjacent column members, and FIG. 1B is a cross-sectional view taken along line xx in FIG. [Figure 8] 13 is a perspective view showing a state in which a groove is formed for inserting a restraining material that restrains a horizontal member that fits within a recess of a pillar member from the upstream side. FIG. [Figure 9] 1(a) is an oblique view showing an example in which a portion of the upstream side of the support surface and retaining surface of the column member is formed into a shape that includes a curved surface corresponding to the surface shape of the horizontal member when the cross-sectional shape of the horizontal member is circular or when a circular steel pipe is used for the steel pipe in the case of steel pipe concrete, and 1(b) is a longitudinal cross-sectional view of 1(a). [Figure 10] This is an oblique view showing the upstream side of a horizontal member installed between column members when the cross-sectional shape of the horizontal member is square, or when a square steel pipe is used as the steel pipe in the case of steel pipe concrete. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] 1 to 4 show an example of the configuration of a disaster prevention structure 1 that includes multiple (plural) pillar members 2 arranged in one direction of the construction object (such as the width direction of the stream) and multiple horizontal members 3 made of reinforced concrete that are erected at intervals in the height direction between adjacent pillar members 2 in that direction. The pillar members 2 are constructed mainly of reinforced concrete or the like directly on the construction object, such as the bed of the stream, or on a foundation of smoothed concrete or the like constructed on the construction object. Hereinafter, "any direction of the construction object" will also be referred to as the width direction of the stream, etc., and the direction perpendicular to that will also be referred to as the "direction of the stream (flow)."

[0042] 1 to 4 and 10 show examples in which the disaster prevention structure 1 is a sabo dam or the like, but the disaster prevention structure 1 can also be constructed as a driftwood capture structure, a rockfall / avalanche prevention fence, etc. When the disaster prevention structure 1 is a sabo dam or the like, walls (sleeves) 4, 4 are constructed on both sides in the width direction of the stream, and a wall-like buttress is constructed as a pillar member 2 between the walls 4, 4. In this case, the wall 4, like the pillar member 2, is constructed of reinforced concrete or the like directly on the construction target, such as the stream bed, or on a foundation constructed on the construction target.

[0043] When the disaster prevention structure 1 is a rockfall prevention fence or the like, the pillar member 2 is formed in a cylindrical shape or the like, but regardless of the formation of the recess 21, the pillar member 2 is given a cross-sectional shape and cross-sectional performance that can sufficiently resist the impact force received by the horizontal member 3 and transmit the force to the foundation or the like. Depending on the construction location of the disaster prevention structure 1, the axial direction of the pillar member 2 may be oriented vertically or inclined relative to the vertical.

[0044] 1 to 4 particularly show an example of the installation of horizontal member 3 when the horizontal member 3 is made of concrete-filled steel pipe (CFT) in which concrete 32 is filled inside steel pipes 31. Tensile members 33 such as rebars or PC steel members serving as tensile resistance members are arranged in the axial direction within the concrete 32 of the horizontal member 3. The tensile members 33 are basically arranged at equal intervals in the circumferential direction as shown in the figures, but may also be arranged in a concentrated manner on the downstream side, which becomes the tension side when an impact force (load) due to a debris flow or the like acts.

[0045] In addition, tension is applied in advance to the PC steel member serving as the tension member 33, which is located downstream and becomes the tension side when the horizontal member 3 is subjected to an impact force from a debris flow or the like, and prestress is sometimes introduced in the axial direction to the concrete 32 on the tension side.

[0046] As shown in Figure 5, the end faces on both sides in the axial direction of the horizontal member 3 have inclined surfaces 3a that are inclined with respect to a plane perpendicular to the axial direction of the horizontal member 3, and the support surface 2a of the pillar member 2 that supports the inclined surface 3a of the horizontal member 3 in the direction of the debris flow, etc., has an inclined surface that corresponds to the inclined surface of the horizontal member 3. The horizontal member 3 is supported by the pillar member 2 while being in surface contact with the support surface 2a of the pillar member 2 at the inclined surface 3a. Both the inclined surface 3a and the support surface 2a are inclined surfaces that are inclined with respect to the plane perpendicular to the axial direction of the horizontal member 3 in a direction such that the axial length of the horizontal member 3 gradually increases from the downstream side to the upstream side of the construction target, such as a mountain stream.

[0047] The end face of the horizontal member 3 may be entirely inclined 3a as shown in Figures 5 and 7, or may only be partially inclined 3a as shown in Figures 6-(a) to (c). In either case, the inclined face 3a is basically a vertical face, but it may also be a face inclined relative to the vertical direction. When part of the end face is inclined 3a, the part of the end face other than the vertical face 3a becomes a vertical face 3b perpendicular to the axial direction, etc.

[0048] 6-(a) and (b) show cases where an inclined surface 3a is formed from the downstream side to partway up the upstream side of the construction target, and a vertical surface 3b is formed on the upstream side as an end surface. In these cases, the inclined surfaces 3a, 3a of adjacent horizontal members 3, 3 sandwiching the column member 2 contact the support surfaces 2a, 2a of the column member 2, and the vertical surfaces (end surfaces) 3b, 3b contact each other. (b) shows an example where a vertical surface 3c parallel to the axial direction of the horizontal member 3 is formed on the downstream side of the vertical surfaces 3b, 3b that contact each other. In this example, the vertical surface 3c parallel to the axial direction of the horizontal member 3 contacts the vertical surface 2g formed on the upstream side of the column member 2.

[0049] Fig. 6-(c) shows a case where a slope 3a is formed from the upstream side to the middle of the downstream side of the construction target, and a vertical surface 3b is formed on the downstream side of the slope 3a. In this case, too, the slopes 3a, 3a of the horizontal members 3, 3 adjacent to each other across the pillar member 2 contact the support surfaces 2a, 2a of the pillar member 2, but the vertical surface 3b contacts the side surface of the pillar member 2 in the stream width direction (thickness direction), etc.

[0050] 3 and 4, a recess 21 having a shape corresponding to the three-dimensional shape of the end of the horizontal member 3 is formed in the portion of the pillar member 2 in which the axial end of the horizontal member 3 is accommodated, so that the pillar member 2 can support the horizontal member 3. The downstream side of this recess 21 becomes the support surface 2a that supports the inclined surface 3a of the horizontal member 3 in the direction of a debris flow or the like.

[0051] The support surface 2a is formed in a shape having an inclined surface corresponding to the inclined surface 3a, such as a surface parallel to the inclined surface 3a of the horizontal member 3. Since the support surface 2a of the recess 21, which comes into contact with the inclined surface 3a of the horizontal member 3 in the direction of a debris flow or the like, basically forms a surface substantially parallel to the inclined surface 3a, when the inclined surface 3a is a vertical surface, the support surface 2a also becomes a vertical surface.

[0052] Since the recess 21 appears to be formed from the upstream side to the downstream side of the pillar member 2, the recess 21 is basically formed from the upstream surface of the pillar member 2, but it may also be formed in the middle part of the pillar member 2, such as in the direction of the stream (flow).

[0053] The vertical lower and upper surfaces of the recess 21 become the placement surface 2b and the holding surface 2c, respectively, which can come into contact with the lower and upper surfaces of the end of the horizontal member 3. As shown in Fig. 7-(b), the lower surface of the horizontal member 3 is placed on and comes into contact with the lower placement surface 2b, but the upper surface of the horizontal member 3 does not necessarily come into contact with the upper holding surface 2c.

[0054] When the cross-sectional shape of the horizontal member 3 is circular, or when the steel pipes 31 constituting the horizontal member 3 made of steel pipe concrete are circular steel pipes, the placing surface 2b and the holding surface 2c may be formed into a shape including a curved surface such as a circle corresponding to the surface shape of the horizontal member 3 or the surface shape of the circular steel pipe, as shown in Figures 9-(a) and (b). In this case, the placing surface 2b and the holding surface 2c, together with the support surface 2a, can restrain the horizontal member 3 (steel pipe 31) from both the top and bottom, and in the horizontal direction (the direction of debris flow, etc.).

[0055] When the cross-sectional shape of the horizontal member 3 is circular, or when the steel pipe 31 of the horizontal member 3 made of steel pipe concrete is a circular steel pipe or a square steel pipe, the recess 21 is basically formed in a triangular prism shape, a square prism shape, or the like according to the shape of the end of the horizontal member 3 when viewed vertically on one side of the center of the column member 2 in the stream width direction, as shown in Figures 7 and 8, from the perspective of ease of formation. However, when the cross-sectional shape of the horizontal member 3 is circular, including when it is made of steel pipe concrete, the recess 21 may be formed in a shape having a curved surface corresponding to the portion where the inclined surface 3a of the axial end of the horizontal member 3 is formed, as described above.

[0056] As shown in Fig. 7, a restraining portion 2d is formed on the surface of the upstream side of the column member 2, which is on the upstream side of the horizontal member 3 when the horizontal member 3 is placed in the recess 21, to prevent the horizontal member 3 from falling out of the recess 21. The restraining portion 2d is formed from the lower side, or the upper side, or both above and below the recess 21, as shown in Fig. 7-(b).

[0057] In the example shown in Figure 9, the support surface 2b and the holding surface 2c are formed in a curved shape corresponding to the surface of the horizontal member 3, so that the restraint portions 2d in the example of Figure 7 are formed above and below the recess 21 on the surface side of the pillar member 2 (upstream side of the recess 21) of the support surface 2b and the holding surface 2c, and therefore there is no need to form or arrange the restraint portions 2d separately.

[0058] The restraining portion 2d may be formed as a part of the column member 2 as shown in Figures 7 and 9, but may also be made of reinforced concrete or steel as a separate body from the column member 2 as a restraining member 2e replacing the restraining portion 2d shown in Figure 7 as shown in Figure 8. In the case of Figure 8, a groove 2f is formed in the column member 2 on the upstream side of the recess 21 in a portion where the upper and lower parts of the restraining member 2e are placed. The horizontal member 3 is mainly subjected to impact forces from a debris flow or the like toward the downstream side when a debris flow or the like occurs, and is not subjected to loads toward the upstream side under normal circumstances, so the groove 2f may be formed only on the lower side of the recess 21.

[0059] In addition, although not shown, there is a method in which the groove 2f is not formed in the recess 21, and the restraining material 2e is overlapped and joined to the upstream surface of the pillar member 2 that sandwiches the recess 21 from above and below. In that case, the restraining material 2e is fixed to the pillar member 2 by a bolt or anchor bolt that penetrates the restraining material 2e itself and is inserted and fixed into the pillar member 2, or a post-installed anchor.

[0060] Figure 10 shows an example of the configuration of a disaster prevention structure (sabo dam) 1 in which the horizontal member 3 has a square cross-sectional shape or the steel pipe 31 of the horizontal member 3 made of steel pipe concrete is a square steel pipe, the horizontal member 3 is erected between adjacent column members 2, 2, the axial ends are stored in each recess 21, and the horizontal member 3 is supported on the support surface 2b.

[0061] In this case, the inclined surface 3a of the horizontal member 3 is the same as when the cross-sectional shape of the horizontal member 3 is circular, so the support surface 2a of the recess 21 is basically a vertical surface. When the cross-sectional shape of the horizontal member 3 is rectangular, including when it is made of steel pipe concrete, and the horizontal member 3 is erected so that each surface of the horizontal member 3 forms a vertical plane and a horizontal plane, the placement surface 2b and holding surface 2c of the recess 21 will be horizontal surfaces.

[0062] In this example, the cross-sectional shape of the horizontal member 3 is rectangular, so that the placement surface 2b and the holding surface 2c can be made horizontal, and the stability of the horizontal member 3 when supported by the column member 2 is higher than when the cross-sectional shape is circular. Therefore, there is less need to form a restraining portion 2d for restraining the horizontal member 3 to the column member 2 or to join a restraining member 2e, and the structure of the column member 2 is simplified compared to when it is circular. [Explanation of symbols]

[0063] 1……Disaster prevention structure, 2...Column member, 21...Recess, 2a...Support surface, 2b...Placement surface, 2c...Holding surface, 2d...Restraint part, 2e...Restraint material, 2f...Groove, 2g...Vertical surface, 3...Horizontal material, 3a...Slanted surface, 3b...Vertical surface, 3c...Vertical surface, 31...Steel pipe, 32...Concrete, 33...Tensile material, 4...Wall section.

Claims

1. The present invention comprises a plurality of column members arranged at intervals in any direction of the construction object, and a plurality of horizontal members made of steel pipe concrete installed at intervals in the height direction between the column members adjacent in the width direction, The end faces on both sides of the horizontal member in the axial direction have inclined surfaces that are inclined with respect to a plane perpendicular to the axial direction of the horizontal member in a direction in which the axial length of the horizontal member gradually increases from the downstream side to the upstream side of the construction target, The support surface of the column member that receives the inclined surface of the horizontal member has an inclined surface corresponding to the inclined surface of the horizontal member, A disaster prevention structure characterized in that the inclined surface of the horizontal member is supported by the pillar member while being in surface contact with the support surface of the pillar member.

2. A recess is formed on the upstream surface of the pillar member into which the axial end of the horizontal member is inserted, and the downstream side of the recess serves as the support surface. Below and above the support surface, a placement surface and a support surface are formed that can support the axial end of the horizontal member from above and below. A disaster prevention structure as described in claim 1, characterized in that the ends on both axial sides of the horizontal member are in surface contact with the support surface of the column member, while being sandwiched from above and below by the placement surface and the holding surface.

3. A disaster prevention structure as described in claim 1 or claim 2, characterized in that a restraint portion is formed or arranged on the upstream surface of the column member on the upstream side of the horizontal member when the axial end of the horizontal member is located within the recess, to prevent the horizontal member from falling out of the recess.

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