Retaining wall guard fence and construction method thereof

Abstract

To provide a retaining wall guard fence, which can be constructed with simple work in a stable posture right on top of upper surface of an existing retaining wall, and a construction method thereof.SOLUTION: There are an expanded concrete support layer 30 constructed on-site on the top surface of an existing retaining wall 10, and multiple anchor materials 40 that penetrate the expanded support layer 30 and are fixed to the back ground G to position the expanded support layer 30; the expanded support layer 30 has an expanded top surface 31 that is wider than the top surface 11 of the existing retaining wall 10, and an expanded portion 32 that protrudes from the top surface 11 of the existing retaining wall 10 toward the mountainside slope; the head parts of the anchor materials 40 are fixed to an inclined position on the mountainside slope of the expanded portion 32 of the expanded support layer 30 to position the expanded support layer 30 so that it cannot be displaced, and the lower parts of pillars 21 are set upright by being planted on the expanded top surface 31 of the expanded support layer 30.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a protective fence for capturing avalanches, rockfalls, and other falling objects such as collapsed earth and sand, and particularly to a protective fence for retaining walls constructed on the upper part of existing retaining walls such as leaning retaining walls and a method for constructing the same.

Background Art

[0002] As a protective facility for preventing disasters caused by falling objects such as avalanches, rockfalls, and collapsed earth and sand, a protective fence including a plurality of columns and a protective net is known. The kinetic energy of the falling object acting on the protective net is ultimately supported by the columns. As one of the methods for installing the columns of these protective fences, a method of burying the lower part of the column in a concrete fence foundation is known, and the kinetic energy acting on the column is supported by the fence foundation (Patent Document 1).

[0003] On the other hand, as a gravity retaining wall for protecting a slope, a leaning retaining wall that resists earth pressure by its own weight while leaning is known. In some cases, a protective fence may be additionally installed on the upper part of this existing leaning retaining wall. As a method for constructing a protective fence on the upper part of an existing leaning retaining wall, it has been proposed to construct a large concrete fence foundation wider than the top surface on the upper part of the existing retaining wall, erect columns on the newly provided fence foundation after raising it, and construct a protective fence (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The conventional construction technology of protective fences has the following points to be improved. <1>In addition to the need to excavate the mountain-side slope of the existing retaining wall or perform ground improvement, a large fence foundation must be added to the upper part of the existing retaining wall. Therefore, constructing a protective fence on the upper part of an existing retaining wall requires a lot of cost and construction period. <2>Although it is conceivable to erect a support column at the top edge of the existing retaining wall that leans, generally, since the depth of the top surface of the existing retaining wall is only about 50 cm, which is very narrow, it is technically difficult to erect a support column while maintaining a stable posture on the top surface of the retaining wall. <3>Even if it were possible to construct a protective fence by erecting a support column at the top edge of the existing retaining wall that leans, the top edge of the existing retaining wall would be damaged due to being unable to withstand the impact load during impact.

[0006] The present invention has been made in view of the above points, and its object is to provide a protective fence for a retaining wall and a construction method thereof that can construct a protective fence in a stable posture directly above the top surface of an existing retaining wall by simple construction.

Means for Solving the Problems

[0007] The present invention is a protective fence for a retaining wall constructed on the upper part of an existing retaining wall that includes a plurality of support columns and a protective net for capturing falling objects, and includes a concrete-made extended support layer constructed on-site on the top edge surface of the existing retaining wall, and a plurality of anchor materials that penetrate the extended support layer and are fixed to the back ground to position the extended support layer. The extended support layer has an extended top surface wider than the top edge surface of the existing retaining wall and an extended portion protruding from the top edge surface of the existing retaining wall toward the mountain side of the slope. The head of the anchor material is fixed at a biased position on the mountain side of the slope of the extended portion of the extended support layer to position the extended support layer so that it cannot be displaced, and the lower part of the support column is placed on the extended top surface of the extended support layer and erected. In another aspect of the present invention, the depth width of the extended support layer has a dimensional relationship larger than the depth width of the top edge surface of the existing retaining wall. In another aspect of the present invention, a plurality of anchor bolts are implanted in the extended support layer according to the standing positions of the columns, and the base plate at the lower part of the column may be bolted and erected through the plurality of anchor bolts. In another aspect of the present invention, one or more pressure plates are embedded in the extended support layer, and the anchor bolts are fixed to the pressure plates. In another aspect of the present invention, the extended support layer is continuously formed along the top end surface of an existing retaining wall. In another aspect of the present invention, a base plate may be provided at the lower part of the column, and the head of the anchor material may be fixed at a biased position on the slope and ridge side of the base plate.

[0008] In another aspect of the present invention, there is provided a method for constructing a protective fence for a retaining wall, which comprises constructing a protective fence having a plurality of columns and a protective net on the upper part of an existing retaining wall. A concrete extended support layer is constructed on the top end surface of the existing retaining wall on-site. The extended support layer has an extended top end surface wider than the top end surface of the existing retaining wall and an extended part protruding from the top end surface of the existing retaining wall toward the slope and ridge side. The head of the anchor material is fixed to the extended part of the extended support layer to position the extended support layer immovably, and the lower part of the column is placed on the extended top end surface of the extended support layer and erected. In another aspect of the present invention, when constructing the extended support layer, a plurality of anchor bolts are implanted in the extended support layer according to the standing positions of the columns, and the base plate at the lower part of the column may be bolted and erected through the plurality of anchor bolts. In another aspect of the present invention, one or more pressure plates may be embedded in the extended support layer, and the anchor bolts may be fixed to the pressure plates. In another aspect of the present invention, a base plate may be provided at the lower part of the column, and the head of the anchor material may be fixed at a biased position on the slope and ridge side of the base plate.

Advantages of the Invention

[0009] The present invention has at least one of the following advantages. <1>In the present invention, by combining an extended support layer constructed on the top end surface of an existing retaining wall and an anchor material for positioning the extended support layer, the top end surface of the existing retaining wall can be effectively utilized to erect the columns of the protective fence in a stable posture. <2>By utilizing an anchor material fixed to the back ground without connecting between the extended support layer and the top end surface of the existing retaining wall, the extended support layer can be positioned in a non-displaceable manner. Therefore, a protective fence can be easily constructed on the upper part of the existing retaining wall. <3>If the head of the anchor material is fixed to an extended portion outside the top end surface of the existing retaining wall, the anchor material can be installed in a short time and easily without penetrating the top end surface of the existing retaining wall. <4>The impact force transmitted to the column is supported by the back ground through the anchor material, so that excessive stress does not concentrate on the extended support layer or the top end surface of the existing retaining wall, and damage to the upper part of the extended support layer or the existing retaining wall can be effectively avoided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

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Figure 6

Figure 7

Figure 8

Figure 9

Best Mode for Carrying Out the Invention

[0011] Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1]

[0012] <1> Leaning type existing retaining wall Referring to FIGS. 1 to 3, the leaning type existing retaining wall 10 is a gravity retaining wall provided on a slope, and includes a cast-in-place concrete structure, a laminated structure of precast concrete blocks, and the like. In the present invention, when installing the guardrail 20 on the upper part of the existing retaining wall 10, a concrete expansion support layer 30 is constructed on-site on the top end surface 11 of the existing retaining wall 10, and the columns 21 of the guardrail 20 are erected using this expansion support layer 30 as a support base.

[0013] <1.1> Expansion support layer The expansion support layer 30 is a mortar or concrete base layer for supporting the columns 21, and has an expanded top end surface 31 wider than the top end surface 11 of the existing retaining wall 10 and an expansion part 32 protruding from the top end surface 11 to the slope mountain side. As shown in FIG. 4, a plurality of anchor bolts 33 are implanted in the expansion support layer 30 according to the erection positions of the columns 21. If necessary, a metal or fiber reinforcing material is embedded in the expansion support layer 30, or short fibers or long fibers are mixed in to reinforce the expansion support layer 30.

[0014] In the expansion part 32 of the expansion support layer 30, a plurality of through holes 35 are opened along the longitudinal direction of the expansion support layer 30, and the expansion support layer 30 can be positioned by the anchor materials 40 inserted into each through hole 35.

[0015] <1.1.1> Total length of the expansion support layer The expansion support layer 30 is formed continuously along the top end surface 11 of the existing retaining wall 10, but the expansion support layer 30 may be partially (completely) formed according to the erection positions of the columns 21.

[0016] <1.1.2> Layer thickness of the expansion support layer (FIG. 5) The layer thickness of the extended support layer 30 is uniform throughout its entire length, and in practical use, a layer thickness of about 400 mm is sufficient.

[0017] <1.1.3>Depth dimension of the extended support layer (Figure 6) When the depth width of the top end surface 11 of the existing retaining wall 10 is B1 and the depth width of the extended top end surface 31 of the extended support layer 30 is B2, the depth width B2 of the extended top end surface 31 has a dimensional relationship that is larger than the depth width B1 of the top end surface 11. Such a dimensional relationship is for substantially expanding the depth width B1 of the top end surface 11 of the existing retaining wall 10.

[0018] The depth width B2 of the extended support layer 30 is a dimension obtained by adding the protruding dimension (about 100 - 150 mm) of the extended portion 32 to the depth width B1 of the top end surface 11. That is, when the depth width B1 of the top end surface 11 is, for example, 500 mm, the depth width B2 of the extended top end surface 31 is 600 - 650 mm.

[0019] <1.2>Anchor material The anchor material 40 is a fixing member for positioning the extended support layer 30 by obtaining reaction force from the back ground G of the existing retaining wall 10. The anchor material 40 is inserted through the through hole 35 provided in the extended portion 32 of the extended support layer 30. The length of the fixed length portion of the anchor material 40 is appropriately selected according to the site conditions. For the anchor material 40, inexpensive tension members such as round steel bars and ground anchors are used.

[0020] <1.3>Fixing position of the anchor material (Figures 3, 6) The through hole 35 may be provided at any position of the extended support layer 30. However, if it is formed within the formation range of the top end surface 11 of the existing retaining wall 10, a new through hole for inserting the anchor material 40 into the top end surface 11 has to be drilled. By forming the through hole 35 in the extended portion 32 of the extended support layer 30 that extends to the slope mountain side, the anchor material 40 can be fixed to the back ground G avoiding the top end surface 11 of the existing retaining wall 10. By offsetting the fixing position of the anchor material 40 with respect to the extension support layer 30 toward the slope mountain side, not only can the horizontal movement of the extension support layer 30 be effectively suppressed, but also the anti-tipping effect of the extension support layer 30 and the support column 21 is improved.

[0021] <2> Overview of the protective fence This will be described with reference to FIGS. 1 and 2. The protective fence 20 is a protective facility for avalanche countermeasures, landslide debris countermeasures, or falling rock countermeasures, and is appropriately selected according to the intended use. The protective fence 20 includes a plurality of support columns 21 erected on the extension support layer 30 and a protective net 25 provided between adjacent support columns 21. In FIG. 1, a shape-maintaining rope 29 is horizontally spanned between the heads of the support columns 21, but the shape-maintaining rope 29 is not essential.

[0022] <2.1> Support column The support column 21 includes a terminal support column, an intermediate support column, or an intermediate terminal support column. The support column 21 includes a base plate 22 integrally provided at the lower part of the support column 21. For the support column body constituting the support column 21, known support column structures such as steel pipes, columns, mortar-filled steel pipes, H-beams, etc. can be used, for example. The base plate 22 is a steel plate having dimensions larger than the cross-sectional shape of the support column 21 and is integrally fixed to the support column 21 by welding or the like. The base plate 22 has a plurality of bolt holes 22a at its peripheral edge (FIG. 4).

[0023] <2.2> Erection means of the support column In the extension support layer 30, a plurality of anchor bolts 33 and one or more bearing plates 34 are embedded when forming the extension support layer 30 (FIG. 5). In order to increase the support bearing capacity of the anchor bolt 33, the head of each anchor bolt 33 is fixed to the bearing plate 34 within the extension support layer 30. The support column 21 fixes the base plate 22 with a plurality of anchor bolts 33 protruding upward from the extension support layer 30 and nuts 37. Note that the number of installed bearing plates 34 is not limited to two and can be appropriately selected.

[0024] <2.3> Protective net The protective net 25 includes at least a plurality of rope materials 26 and a net material 27. The protective net 25 may additionally include a known buffer device.

[0025] In this example, a form is shown in which a rope material 26 that can be horizontally installed over a plurality of spans is combined with a net material 27 made of a diamond wire mesh. Both ends of each rope material 26 are connected to a terminal support or an intermediate terminal support, and at the intersection of the intermediate support 21b and each rope material 26, the intermediate support moors each rope material 26 in a state where it can slide. Furthermore, a plurality of spacing retainers 28 are attached between the plurality of rope materials 26 provided in multiple stages to maintain the spacing between the rope materials 26. The configuration of the protective net 25 is appropriately selected according to the type of falling objects, the amount of falling objects, etc.

[0026] [Method for constructing a protective fence] Next, a method for constructing a protective fence 20 on the upper part of the existing retaining wall 10 will be described.

[0027] <1> Preliminary preparation As shown in FIG. 4, foreign matters such as deteriorated concrete pieces, mosses, and salts such as snow melting agents often adhere to the top surface 11 of the existing retaining wall 10. Therefore, these foreign matters are removed using a known chipping tool, brush, etc., and the top surface 11 is cleaned beautifully.

[0028] <2> Formation of the extended support layer A formwork is assembled on the upper part of the existing retaining wall 10. After setting the pressure plate 34 and a plurality of anchor bolts 33 in the formwork according to the planned installation positions of the supports 21, mortar or concrete is placed in the formwork to construct the extended support layer 30. When constructing the extended support layer 30, a pipe material for punching out a box or the like is set in the extended part 32 of the extended support layer 30 to form a through hole 35 (FIG. 7). Since the extended support layer 30 has a larger area than the top end surface 11 of the existing retaining wall 10, a plurality of anchor materials 40 can be implanted in the extended support layer 30 without being affected by the area of the top end surface 11.

[0029] <2.1>Formation of the adjustment layer On the upper surface of the extended support layer 30, an adjustment layer 36 made of non-shrink mortar is formed at the planned installation position of the support column 21 (Figure 4). In practice, the layer thickness of the adjustment layer 36 may be about 30 mm, and the planar area of the adjustment layer 36 may be the minimum dimension that allows the base plate 22 to be placed. Note that the adjustment layer 36 is not essential and may be omitted in some cases.

[0030] <3>Fixing of the anchor material A plurality of anchor materials 40 are fixed to the backfill ground G of the existing retaining wall 10 along the extended support layer 30. After setting washers 41 on the heads of the respective anchor materials 40, the fixing nuts 42 are tightened to fix the extended support layer 30 (Figure 7).

[0031] It is also possible to fix the anchor material 40 by penetrating the top end surface 11 of the existing retaining wall 10, but the operation of drilling the existing retaining wall 10 requires a lot of time and labor. Therefore, if a through hole 32 is formed in the extended portion 32 that is separated from the top end surface 11 of the existing retaining wall 10, the anchor material 40 can be installed quickly and easily without penetrating the top end surface 11.

[0032] <4>Assembly of the protective fence After the subsequent operations, the protective fence 10 is assembled on the extended support layer 30.

[0033] <4.1>Installation of the support column Nuts 37 are tightened on each anchor bolt 33 protruding directly above the adjustment layer 36 to fix the base plate 22, and the support column 21 is erected at a predetermined position on the extended support layer 30 (Figures 5 and 6).

[0034] <4.2>Installation of the protective net As shown in FIG. 1, a plurality of rope members 26 are horizontally installed in multiple stages between the columns 21 erected on the extended support layer 30, and the ends of each rope member 26 are fixed to the terminal columns 21a. An interval maintaining member 28 is cross-mounted between the plurality of rope members 26 provided in multiple stages. The slope mountain side of the plurality of rope members 26 is covered with a net material 27 to assemble a protective net 25. The intersection of the rope member 26 and the net material 27 is connected by a coil material 23 or the like.

[0035] If necessary, a holding rope (not shown) is connected between the head of each column 21 and the slope mountain side anchor, or between the head of each column 21 and the slope valley side anchor.

[0036] [Self-supporting structure of the protective fence] Next, the self-supporting structure of the protective fence 20 will be described.

[0037] <1> Relationship between the top end surface of the existing retaining wall and the extended support layer As shown in FIGS. 1 and 2, the protective fence 20 is erected on the upper surface of the extended support layer 30 formed on the upper part of the existing retaining wall 10 so as to be self-supporting. Regarding the relationship between the top end surface 11 of the existing retaining wall 10 and the extended support layer 30, the extended support layer 30 is only placed on the top end surface 11 of the existing retaining wall 10, and there is no member directly connecting between the extended support layer 30 and the top end surface 11.

[0038] <2> Fixing means of the extended support layer The extended support layer 30 is positioned in a state where horizontal displacement is impossible by a plurality of anchor materials 40 fixed to the back ground G through through holes 35 formed biased toward the slope mountain side of the extended support layer 30, and load transmission between the extended support layer 30 and the back ground G is possible through the anchor materials 40.

[0039] <3> Relationship between the extended support layer and the column Between the lower part of the support column 21 that constitutes the protective fence 20 and the extended support layer 30, a plurality of anchor bolts 33 and nuts 37 are rigidly connected, enabling load transfer between the support column 21 and the extended support layer 30 (Figure 6).

[0040] <4>Support of impact load In Figure 2, when a falling object W such as a rockfall drops from the slope mountain side and collides with the protective net 25 of the protective fence 20, the protective net 25 stretches and deforms toward the valley side while absorbing the kinetic energy of the falling object W. The impact force acting on the protective net 25 is transmitted to the support column 21. The impact force transmitted to the support column 21 is supported by the frictional resistance of the contact surface between the lower surface of the extended support layer 30 and the top end surface 11 of the existing retaining wall 10, as well as the shear strength and tensile strength of the plurality of anchor materials 40 connected to the extended support layer 30. Therefore, the impact force finally transmitted to the support column 21 through the protective net 25 is supported by the backfill ground G through the anchor material 40. As a result, excessive stress does not concentrate on the extended support layer 30 or the top end surface 11 of the existing retaining wall 10, and damage to the upper part of the extended support layer 30 or the existing retaining wall 10 can be effectively avoided.

[0041] <5>Overturning moment of the extended support layer (support column) When an impact force acts on the protective net 25, an overturning moment in the counterclockwise direction acts on the support column 21. The overturning moment acting on the support column 21 is transmitted to the extended support layer 30 via the anchor bolt 33 and the bearing plate 34.

[0042] When an overturning moment in the counterclockwise direction acts on the extended support layer 30, it attempts to rotate with the front end P of the extended support layer 30 in contact with the top end surface 11 of the retaining wall 10 as a fulcrum, but the anchor material 40 provided at the rear end of the extended support layer 30 effectively restrains the rotation of the extended support layer 30.

[0043] Since the fixing position of the anchor member 40 is biased toward the slope peak side with respect to the installation position of the support column 21, the support reaction force of the anchor member 40 during impact can be smaller compared to the form in which the fixing position of the anchor member 40 is aligned with the installation position of the support column 21.

[0044] [Embodiment 2] Other embodiments will be described hereinafter. In the description thereof, the same parts as those in the above-described embodiments are denoted by the same reference numerals, and the detailed description thereof is omitted.

[0045] <1> Configuration Referring to FIGS. 8 and 9, another form in which the head of the anchor member 40 is fixed to a part of the end plate 22 will be described. In the previous Embodiment 1, the form in which the head of the anchor member 40 is fixed to the extended support layer 30 was described. However, the head of the anchor member 40 may be fixed to the slope peak side of the base plate 22 of the support column 21. An anchor hole 22b is formed on the slope peak side of the base plate 22 of the support column 21, and the anchor member 40 is inserted through the anchor hole 22b and the through hole 35 of the extended support layer 30. The head of the anchor member 40 is fixed to the base plate 22 via a washer 41 and a fixing nut 42.

[0046] <2> Effects of this Example In this embodiment, in addition to obtaining the same effects as those in the previous Embodiment 1, by fixing the slope peak side of the base plate 22 of the support column 21 with the head of the anchor member 40, the stability of the posture of the support column 21 is further improved, and the effect of suppressing damage to the upper part of the extended support layer 30 and the existing retaining wall 10 at the installation position of the support column 21 is improved.

Description of Reference Numerals

[0047] G ····· Back ground of the existing retaining wall 10 ····· Existing retaining wall 11 ····· Top end surface of the existing retaining wall 20 ····· Protection fence 21 ····· Support column 21a ··· Terminal support column 21b ··· Intermediate support column 22····Base plate 22a···Bolt holes of the base plate 22b···Anchor holes of the base plate 23····Coil material 25····Protective net 26····Rope material 27····Net material 28····Spacing retainer 29····Shape-maintaining rope 30····Expansion support layer 31····Expanded top surface 32····Expansion part of the expansion support layer 33····Anchor bolt 34····Bearing plate 36····Adjustment layer 37····Nut 40····Anchor material 41····Washer 42····Fixed nut

Claims

1. A protective fence for a retaining wall constructed on top of an existing retaining wall that has multiple columns and a protective net and captures falling debris, a concrete-made extended support layer constructed on-site on the top end surface of the existing retaining wall, and a plurality of anchor materials that penetrate the extended support layer and are fixed to the back ground to position the extended support layer. The extended support layer has an extended top end surface that is wider than the top end surface of the existing retaining wall, and an extended portion that protrudes from the top end surface of the existing retaining wall toward the slope mountain side. The head of the anchor material is fixed at a biased position on the slope mountain side of the extended portion of the extended support layer to position the extended support layer so that it cannot be displaced. Characterized in that the lower part of the column is placed on the extended top end surface of the extended support layer and erected. A protective fence for a retaining wall.

2. The protective fence for a retaining wall according to claim 1, characterized in that the depth width of the extended support layer has a dimensional relationship greater than the depth width of the top end surface of the existing retaining wall.

3. The protective fence for a retaining wall according to claim 1, characterized in that a plurality of anchor bolts are implanted in the extended support layer according to the erected position of the column, and the base plate at the lower part of the column is bolted through the plurality of anchor bolts and erected.

4. The protective fence for a retaining wall according to claim 3, characterized in that one or more pressure plates are embedded in the extended support layer, and the anchor bolts are fixed to the pressure plates.

5. The protective fence for a retaining wall according to claim 1, characterized in that the extended support layer is continuously formed along the top end surface of the existing retaining wall.

6. The protective fence for a retaining wall according to claim 1, characterized in that a base plate is provided at the lower part of the column, and the head of the anchor material is fixed at a biased position on the slope mountain side of the base plate.

7. A construction method for a protective fence for a retaining wall that constructs a protective fence with multiple columns and a protective net on top of an existing retaining wall, constructing a concrete-made extended support layer on-site on the top end surface of the existing retaining wall, wherein the extended support layer has an extended top end surface that is wider than the top end surface of the existing retaining wall, and an extended portion that protrudes from the top end surface of the existing retaining wall toward the slope mountain side, while fixing the head of the anchor material to the extended portion of the extended support layer to position the extended support layer so that it cannot be displaced, characterized in that the lower part of the column is placed on the extended top end surface of the extended support layer and erected. A construction method for a protective fence for a retaining wall.

8. When constructing the extended support layer, a plurality of anchor bolts are implanted in the extended support layer according to the standing positions of the columns, and the base plate at the lower part of the column is bolted and erected through the plurality of anchor bolts. The method for constructing the retaining wall protection fence according to claim 7, characterized in that.

9. One or more pressure plates are embedded in the extended support layer, and the anchor bolts are fixed to the pressure plates. The method for constructing the retaining wall protection fence according to claim 7, characterized in that.

10. A base plate is provided at the lower part of the column, and the head of the anchor material is fixed at a deviated position on the slope side of the base plate. The method for constructing the retaining wall protection fence according to claim 7, characterized in that.

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