Slope stabilization structure using rock bolt nuts

Abstract

To provide a nut for a lock bolt and a slope stabilization structure using the nut, capable of accommodating changes in a slope angel of the lock bolt to a vertical direction of a ground slope and improving the appearance.SOLUTION: A slope stabilization structure is provided with: lock bolts 14 installed in a ground slope surface S; plates 20 which are installed on the ground slope surface and through which heads of the lock bolts pass; and nuts 50 screwed on the heads of the lock bolts to fix the plates on the ground slope surface. The nut comprises a nut head 56 having a seat surface in a convex spherical shape abutting to a nut support part of the plate and a cylindrical part 52 being a cylindrical shape projecting from the seat surface and having, on its inner peripheral surface, a screw groove to which the head of the lock bolt is screwed, the cylindrical part being inserted in a through hole of the plate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rock bolt nut that is screwed onto the head of a rock bolt to fix a plate material that is attached to the head of the rock bolt that is driven into a ground slope for slope stabilization. To This concerns the slope stabilization structure used. [Background technology]

[0002] Anchor work, in which multiple anchor members are embedded at intervals into the ground slope of the natural ground, etc., and extend down to a stable layer deeper than the sliding surface of the ground, has been known as a slope stabilization method for preventing slope failure and landslides.Depending on the depth of the sliding layer (moving layer shallower than the sliding surface) of the target ground slope, there are two types of anchor work: the ground anchor method, which is applied when the layer is relatively deep, and the rock bolt method (rebar insertion method), which is applied when the layer is relatively shallow.

[0003] The ground anchor method is applied to slopes where the sliding layer is about 5m deep or more and where a large deterrent force is required. The anchor body of the ground anchor method is generally made of PC steel strands and has an anchoring part that is fixed to the stable layer, and a tensioning part that is located in the sliding layer and applies tension. The tensioning force of the anchor body is transmitted to the ground via a pressure plate attached to the head of the anchor body that protrudes from the ground slope. This pressure plate is relatively large (with a long side length of 1m or more) made of concrete or steel and fabricated on-site or in a factory.

[0004] On the other hand, the rock bolt method, which is the subject of this invention, is used in shallow surface areas where the sliding layer is about 3 m deep, and the entire rock bolt extending from the sliding layer to the stable layer is fixed to the ground with grout material.

[0005] In the rock bolt method, rock bolts are installed in a scattered manner, but even if the installation of these rock bolts maintains the slide surface, a local collapse phenomenon known as a hollow collapse can occur, in which part of the surface layer between adjacent rock bolts falls out.

[0006] To prevent the occurrence of hole-out, a method has been adopted in which a plate material (for example, a small pressure plate with a long side of about 600 mm) is attached to the head of the rock bolt and fixed with a nut, and the plate material is pressed against the ground slope from above. Another method is to lay a mesh body on the target slope and press this mesh body against the slope with a plate material attached to the head of the rock bolt (for example, Patent Document 1).

[0007] The nut is formed in a long cylindrical shape to ensure sufficient thread clearance, and in order to stably fix the plate material to the sloped surface, it is preferable that the axial direction of the nut is perpendicular to the surface of the plate material.

[0008] However, the insertion direction of the rock bolt is determined by the design based on the inclination angle of the natural ground and the inclination angle of the stable layer, and is therefore not necessarily perpendicular to the natural ground surface; rock bolts may be driven at a specified inclination angle from the vertical (for example, at an angle of about 10° from the perpendicular to the natural ground surface). Since the plate members are placed along the natural ground surface, the insertion direction of the rock bolt is not necessarily perpendicular to the surface of the plate members. Furthermore, since the plate members are also inclined due to the unevenness of the natural ground surface, the insertion direction (axial direction) of the rock bolt is generally inclined from the perpendicular to the surface of the plate members.

[0009] Since the axial direction of the nut coincides with the axial direction of the lock bolt, when the lock bolt is tilted from the vertical direction, the axial direction of the nut is tilted from the vertical direction relative to the surface of the plate material.

[0010] In such cases, a portion of the nut seating surface comes into strong local contact with the nut support surface of the plate, making it difficult to stably fix the plate.In slope stabilization structures in which a mesh with high tensile strength (so-called high-strength net) is laid on the surface of the natural ground, if the plate is not stably fixed, the tensile performance of the high-strength net cannot be fully demonstrated.

[0011] To address the problem of tilting from the vertical direction relative to a ground slope, Patent Document 2 discloses a device in which a first washer with a convex spherical lower surface and a second washer with a concave spherical upper surface are interposed between the nut and the plate material. The flat upper surface of the first washer abuts against the flat lower end surface of the nut, and the convex spherical lower surface abuts against the concave spherical surface of the second washer. The lower surface of the second washer is flat and abuts against the flat nut support surface of the plate material.

[0012] In this way, by interposing two washers with corresponding concave and convex spherical surfaces between the nut and the nut support surface of the plate material, it is possible to prevent localized contact with the plate material even if the axial direction of the nut is inclined from the perpendicular direction to the surface of the plate material. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 2019-94692 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-184855 Summary of the Invention [Problem to be solved by the invention]

[0014] In the slope stabilization structure using washers described in Patent Document 2, two washers are interposed between the plate material and the nut, so the protruding length from the plate material to the ground is increased by the total length of the cylindrical nut plus the thickness of the washers.

[0015] However, if the protrusion from the plate material becomes too large, it may be damaged by falling rocks or the appearance of the slope after installation may be impaired. In particular, if there is variation in the insertion direction of the rock bolts, the aesthetic appeal of the slope stabilization structure installation area may be impaired.

[0016] The present invention has been made in view of the above-mentioned problems, and provides a nut for a rock bolt that can accommodate changes in the inclination angle of the rock bolt relative to the vertical direction of the ground slope and can suppress the obstruction of the scenery. To The present invention aims to provide a slope stabilization structure using a stabilization method. [Means for solving the problem]

[0019] above In order to achieve the above object, the claims of the present invention 1 The slope stabilization structure related to Rock bolts installed on the ground slope, a plate material installed on the ground slope and having a through hole through which the head of the rock bolt passes; a nut threaded onto the head of the rock bolt to fix the plate material to the ground slope, A protective member is provided which is disposed between the lower end surface of the nut and the grout material filled inside the drilled hole for the rock bolt and covers the outer periphery of the rock bolt; The nut is a nut head having a convex spherical seat that contacts the nut support portion of the plate material; a cylindrical portion that protrudes from the seating surface, has a screw groove on its inner circumferential surface into which the head of the lock bolt screws, and is inserted into the through hole of the plate material; death, The protective member includes a cylindrical sponge surrounding the outer periphery of the lock bolt and a time-hardening filler filled in the sponge. It is characterized by:

[0020] With this configuration, if a rock bolt is driven at an angle inclined to the ground slope rather than perpendicular to it, the axial direction of the nut screwed onto the rock bolt will also be inclined rather than perpendicular to the surface of the plate material placed on the ground slope. However, the convex spherical seating surface of the nut head abuts evenly around the periphery of the seating surface without localized contact with the nut support surface of the plate material, preventing the generation of localized stress even when the rock bolt is driven at an angle inclined to the ground slope. Furthermore, the cylindrical portion of the nut having a threaded groove is inserted into the through hole of the plate material and is not visible from the ground side. Therefore, the presence of the cylindrical portion allows for a sufficient threading area with the head of the rock bolt while reducing the protruding length of the nut head that protrudes from the plate material to the ground side, thereby minimizing the disruption to the landscape of the area where the slope stabilization structure is installed. Furthermore, the area of ​​the lock bolt below the nut is covered and protected by the protective member, thereby preventing corrosion of the lock bolt.

[0021] Furthermore, the claims of the present invention 2 The slope stabilization structure according to claim 1 In the slope stabilization structure described in The nut support portion is formed by raising the periphery of the through hole on the upper surface side of the plate material, and the inner surface of the raised portion is formed into a concave spherical surface that receives the convex spherical seating surface of the nut. Nona It is characterized by being configured as a mat support surface.

[0022] This configuration increases the contact area between the nut seat and the nut support surface of the plate material, reducing the surface pressure per unit area. Furthermore, by providing the raised portion and making its inner surface spherical, a wide range of inclination angles of the nut can be accommodated regardless of the thickness of the plate. Furthermore, since a sufficient area of ​​the nut support surface can be secured, it is possible to prevent the nut from sinking into the nut support surface and thus prevent loosening.

[0023] Furthermore, the claims of the present invention 3 The slope stabilization structure according to claim 1 or 2In the slope stabilization structure described in The head of the rock bolt protrudes above the upper surface of the plate material when the plate material is installed on the ground slope. do.

[0024] This configuration makes it easy to tighten the nut onto the lock bolt.

[0027] Furthermore, the claims of the present invention 4 The slope stabilization structure according to claim 1 ~ 3 In the slope stabilization structure according to any one of the above items, The nut head is characterized by being formed in a substantially spherical shape that covers the head of the lock bolt.

[0028] With this configuration, the nut head is formed in a roughly spherical shape, so even if there is variation in the insertion direction of multiple rock bolts driven into the ground slope, the shape of the nut head when viewed from the ground will be a roughly uniform spherical shape, improving the aesthetic appearance after installation. In addition, the amount of protrusion of the nut head is reduced, making it possible to prevent damage from falling rocks.

[0029] Furthermore, the claims of the present invention 5 The slope stabilization structure according to claim 1 ~ 4 In the slope stabilization structure according to any one of the above items, The nut head has a recess on the top surface into which a tightening tool is fitted.

[0030] With this configuration, a tightening tool such as a torque wrench can be fitted into the recess formed on the top surface of the nut head, making it easy to tighten the nut. In other words, since it is configured as a recess, it is not noticeable from the outside, making it a structure that is both aesthetically pleasing and easy to install.

[0031] Furthermore, the claims of the present invention 6 The slope stabilization structure according to claim 1 ~ 4In the slope stabilization structure according to any one of the above items, The nut head has a peripheral surface portion formed in a polygonal shape in a plan view between a top surface portion and the seating surface.

[0032] With this configuration, a tightening tool such as a torque wrench can be fitted into the polygonal peripheral surface of the nut head, making it easy to tighten the nut, resulting in a structure that is both aesthetically pleasing and easy to install.

[0033] Furthermore, the claims of the present invention 7 The slope stabilization structure according to claim 1 ~ 6 In the slope stabilization structure according to any one of the above items, a mesh body laid on the ground slope and pressed against the ground slope by the plate material; The plate material has a protrusion that protrudes from the lower surface and penetrates the mesh of the mesh body.

[0034] According to this configuration, the above-mentioned claim 1 ~ 6 In addition to the above effects, the mesh laid on the ground slope can reliably prevent the occurrence of core holes, where parts of the surface layer between adjacent rock bolts fall out. Also, the protrusions of the plate material catch on the mesh, preventing the mesh from moving, preventing the mesh from shifting out of position. [Effects of the Invention]

[0035] Nut for lock bolt according to the present invention UsingAccording to the slope stabilization structure, the bearing surface of the nut head is formed in a convex spherical shape, so that the bearing surface of the nut can be uniformly abutted around the circumferential direction of the nut support part of the plate material even when the rock bolt is inclined rather than perpendicular to the ground slope. Furthermore, the cylindrical part of the nut with the thread groove is inserted into the through-hole of the plate material and is not visible from the ground side, so the protrusion length of the nut head from the plate material to the ground side can be reduced while ensuring sufficient thread allowance of the nut, thereby minimizing obstruction to the scenery. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a perspective view showing a slope stabilization structure according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the slope stabilization structure shown in FIG. 1. [Figure 3] 1A and 1B are diagrams showing a net body, in which (a) is a plan view of the net body and (b) is a side view of the net body. [Figure 4] 1A to 1C are diagrams showing a nut, in which (a) is a side view, (b) is a plan view, and (c) is a bottom view. [Figure 5] 10A, 10B, and 10C are diagrams showing another embodiment of the nut for a lock bolt, in which (a) is a side view, (b) is a plan view, and (c) is a bottom view. [Figure 6] 10A and 10B are diagrams showing another embodiment of the nut for a lock bolt, in which (a) is a side view and (b) is a plan view. [Figure 7] 10A and 10B are diagrams showing another embodiment of the nut for a lock bolt, in which (a) is a cross-sectional view and (b) is a plan view. [Figure 8] 10A and 10B are diagrams showing another embodiment of the nut for a lock bolt, in which (a) is a cross-sectional view and (b) is a plan view. [Figure 9] FIG. 10 is a side view showing a modified example of the nut for the lock bolt. [Figure 10] FIG. 10 is a side view showing a modified example of the nut for the lock bolt. [Figure 11]10A and 10B are diagrams illustrating another example of a plate material, in which (a) is a plan view of the plate material and (b) is a cross-sectional view of the plate material taken along line XX. [Figure 12] 10 is a diagram illustrating the state in which the plate material shown in FIG. 9 is engaged with the mesh body. FIG. [Figure 13] 3 is a cross-sectional view similar to FIG. 2 showing a slope stabilization structure according to a second embodiment of the present invention. [Figure 14] FIG. 3 is a cross-sectional view similar to FIG. 2 showing a reference example of a slope stabilization structure. DETAILED DESCRIPTION OF THE INVENTION

[0037] (First embodiment) FIG. 1 is a perspective view showing a slope stabilization structure according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the slope stabilization structure shown in FIG.

[0038] The slope stabilization structure 10 is installed on a ground slope (hereinafter simply referred to as "slope S") such as natural ground to prevent slope failure and landslides. The ground has a sliding layer (a moving layer shallower than the sliding surface) located on the surface that is easily weathered, and a stable layer that is stable ground located below it. The slope stabilization structure 10 of this embodiment is suitable for use on ground where the sliding layer is within 5 m deep, for example, about 2 to 4 m deep. The inclination angle of the slope S on which the slope stabilization structure 10 is installed is, for example, about 40 to 80 degrees with respect to the horizontal direction.

[0039] The slope stabilization structure 10 comprises a mesh body 12 laid in the installation area of ​​the slope stabilization structure 10, a plurality of rock bolts 14 driven in at intervals in the area where the mesh body 12 is laid, a plate material 20 attached to the head 15 of the rock bolt 14 using a rock bolt nut 50 (hereinafter simply referred to as "nut 50") screwed onto the rock bolt 14, and a filler member 30 arranged between the slope S and the plate material 20.

[0040] A plurality of rock bolts 14 are driven into the slope S at intervals within the construction range of the slope stabilization structure 10. The rock bolts 14 are inserted into holes (bored holes) 16 formed in the ground and extend to the stable layer. They are fixed to the stable layer and the moving layer by grout material 17 filled in the holes 16. The rock bolts 14 are driven into the slope S at a predetermined inclination angle from the perpendicular direction, depending on the position of the stable layer and the direction of the landslide, as necessary. The diameter of the rock bolts 14 may be, for example, approximately 19 mm to approximately 25 mm. In the example shown in FIG. 1 , the heads 15 of the rock bolts 14 are driven into the slope S at an inclination downward from the perpendicular direction. The inclination angle of the rock bolts 14 is, for example, less than 10° from the perpendicular direction. The rock bolts 14 preferably have a zinc plating layer or a zinc-aluminum alloy plating layer on their surfaces.

[0041] The mesh 12 is formed by weaving metal wires 13, which are made of hard steel wires and have a strength of 800N / mm 2 ~2000N / mm 2 The wire 13 has a tensile strength of 1000 MPa. Examples of such wires include wires made from hard steel wires as specified in JIS G 3506, hard steel wires (JIS G 3521), and galvanized steel wires (JIS G 3548). Wires 13 made from hard steel wires are less susceptible to plastic deformation than wires made from soft steel wires as specified in JIS G 3505, and have high tensile strength and spring properties. By using such wires, the mesh body 12 can be made into a high-strength net with high tensile strength. The wires 13 are not limited to those made of metal, and wires made from carbon fiber, glass fiber, aramid fiber, or the like, or wires made from highly corrosion-resistant resins can be used.

[0042] As shown in Fig. 3, the mesh body 12 of this embodiment is a diamond-shaped wire mesh having diamond-shaped meshes 13a. The size of the meshes 13a of the mesh body 12 can be, for example, such that one diagonal length (the shorter one in the mesh 13a in Fig. 3) is 50 to 150 mm, and the other diagonal length (the longer one in the mesh 13a in Fig. 3) is 50 to 200 mm. In addition, a twisted, annular bundling portion 13b is formed at the end of the shorter diagonal of the diamond-shaped mesh located on the side of the mesh body 12, and an end treatment is applied to connect the two bundling portions 13b.

[0043] The mesh body 12 is not limited to a diamond-shaped wire mesh, and may have meshes 13a of, for example, circular shapes. The wire material 13 preferably has a zinc plating layer or a zinc-aluminum alloy plating layer on its surface. The zinc plating layer or zinc-aluminum alloy plating layer may further be coated with a synthetic resin coating layer (e.g., a coating layer of saturated polyester (PET) or polyvinyl chloride (PVC)). This can further improve the corrosion resistance of the mesh body 20.

[0044] The plate material 20 is a plate-like member having through holes 21 through which the lock bolts 14 are inserted, and is fixed to the slope S by nuts 50 that are screwed onto the heads 15 of the lock bolts 14, with the mesh body 12 sandwiched between the plate material 20 and the slope S. The plate material 20 may be made of, for example, a metal such as steel, concrete, or fiber-reinforced resin. Ribs 23 are formed on the periphery of the plate material 20. The through holes 21 are formed in the center of the plate material 20. The inner diameter of the through holes 21 is formed so as to increase toward the lower surface 22b. The plate material 20 of this embodiment is formed in a substantially rectangular shape in a plan view, but the shape in a plan view is not limited to this and may be, for example, another polygonal shape or a circular shape.

[0045] A raised portion 24 is formed in the center of the plate material 20 by raising the upper surface 22a of the plate material around the through hole 21. That is, the raised portion 24 is formed around the through hole 21. The inner surface of this raised portion 24 is configured as a concave spherical nut support surface (nut support portion) 24a so as to receive the convex spherical bearing surface 57 of the nut 50. That is, the nut support surface 24a has a so-called mortar-like shape. As shown in FIG. 2, when viewed as the cross-sectional thickness of the plate material 20, the thickness D2 of the raised portion 24 is greater than the thickness D1 of the surrounding area. Thickness D1 is the thickness of the plate body excluding the ribs 23 and protrusions 26. In this way, by providing the raised portion 24, it is possible to ensure a nut support surface 24a with a sufficient area regardless of the thickness of the plate.

[0046] The lower surface 22b of the plate member 20 has at least one protrusion 26 protruding from the lower surface 22b. The length of the protrusion 26 is equal to or greater than the thickness d of the mesh body 12 shown in Fig. 3. In this embodiment, a plurality of protrusions 26 are formed on the lower surface 22b, and each of the protrusions 26 penetrates the mesh of the mesh body 12 in the installed state.

[0047] The nut 50 is threaded onto the head 15 of the lock bolt 14 to secure the plate material 20 to the slope S. The nut 50 can be formed of, for example, a metal material or a resin material, and preferably has a zinc plating layer or a zinc-aluminum alloy plating layer on its surface. As shown in FIG. 4, the nut 50 has a nut head 56 with a convex spherical bearing surface 57 and a tubular portion 52 protruding from the bearing surface 57. The bearing surface 57 preferably has a thicker plating layer than other surface regions.

[0048] The outer diameter of the nut head 56 is larger than the inner diameter of the through hole 21 of the plate material 20. The nut head 56 of this embodiment is formed in a generally spherical shape that covers the head 15 of the lock bolt 14, and its diameter is larger than the inner diameter of the upper end of the through hole 21. The nut head 56 has a recess 58 on its top surface 56a into which a fastening head 62 of a fastening tool 60 such as a torque wrench is fitted. The recess 58 of this embodiment is formed in a generally rectangular shape in plan view, but is not limited to this and may be another polygonal shape such as a hexagon.

[0049] The tubular portion 52 of the nut 50 is a tubular portion protruding from the seat surface 57. In this embodiment, the tubular portion 52 is formed in a cylindrical shape, but is not limited thereto and may be formed in a polygonal cylindrical shape. The diameter of the tubular portion 52 is formed smaller than the inner diameter of the through hole 21 of the plate member 20. The tubular portion 52 has a female thread portion 54 with a thread groove formed on its inner circumferential surface. In this embodiment, the female thread portion 54 penetrates the tubular portion 52 and extends to the nut head 56. The length of the female thread portion 54 of the nut head 56 is formed longer than the length of the female thread portion 54 of the tubular portion 52. Although not shown, the female thread portion 54 may extend so as to penetrate the nut head 56. In this embodiment, the length of the tubular portion 52 is shorter than the length of the nut head 56 in the axial direction of the nut 50. However, the length of the tubular portion 52 may be equal to or longer than the length of the nut head 56.

[0050] The filling member 30 is placed between the plate material 20 and the slope S when the slope S is uneven (i.e., uneven), to eliminate the unevenness between the plate material 20 and the slope S, to properly engage the protrusions 26 of the plate material 20 with the mesh body 12, and to stabilize the fixed state of the plate material 20 so that the tension force caused by tightening the nuts 50 is properly transmitted to the natural ground. The filling member 30 is placed on the slope S so as to overlap the plate material 20 as necessary. The filling member 30 includes a bag body 32, a porous member 34 loaded inside the bag body 32, and a filler material 36 that hardens over time and is injected into the bag body 32.

[0051] The bag body 32 is formed from a material that is breathable and can retain the filler 36 inside. Examples of such materials that can be used include nonwoven fabric made of polypropylene, polyethylene, polyester, or the like. This nonwoven fabric has pores that are large enough to allow air to pass through and a small amount of water to penetrate, but not allow the filler 36 to penetrate. The bag body 32 can be formed by joining the peripheral portions of two sheets of nonwoven fabric together. The filler member 30 of this embodiment has an insertion hole 38 formed in the center of the bag body 32 for inserting the lock bolt 14.

[0052] The porous member 34 has a large number of pores and / or gaps that can be impregnated with and retain the filler 36, and is also compressible and deformable. Examples of such materials include sponge, urethane foam, pulp products, and palm (lump fiber obtained from palm plants, etc.), but other materials may be used as long as they have the above-mentioned properties. In this embodiment, palm is used as the porous member 34. The filler 36 has a time-hardening property, and is fluid when injected into the bag body 32, and then becomes a solid. In this embodiment, cement milk is used as the filler 36, but the filler is not limited to this and may be, for example, a resin material or a grout material such as mortar.

[0053] The above-described slope stabilization structure 10 can be constructed in the following manner.

[0054] First, the ground slope S is drilled to provide holes 16 for inserting rock bolts 14. Next, the rock bolts 14 are inserted into the holes 16, and grout 17 is injected from the bottom of the holes 16 to install the rock bolts 14 (rock bolt installation process). Multiple rock bolts 14 are installed at intervals on the slope S on which the slope stabilization structure 10 is to be installed. As shown in FIG. 2, the rock bolts 14 are installed so that the heads 15 of the rock bolts 14 protrude above ground from the surface of the mesh body 12 after the mesh body 12 is installed. Furthermore, as shown in FIG. 2, after the plate material 20 is installed, the heads 15 preferably protrude above ground beyond the flat upper surface 22a of the plate material 20, and more preferably protrude above the raised portion 24. Having the rock bolt heads 15 protrude from the plate material 20 in this way makes it easier to thread the nuts 50 onto the rock bolts 14.

[0055] Next, the filler members 30 are placed on the slope S (filler member placement process). The filler members 30 are placed at positions overlapping the plate materials 20, and in this embodiment, the heads of the lock bolts 14 are inserted into the insertion holes 38 formed in the pouches 32 of the filler members 30.

[0056] Next, the mesh body 12 is laid on the slope S, which is the target area for installing the slope stabilization structure 10 (mesh body laying process). After that, the plate material 20 is attached to the heads 15 of the rock bolts 14 that penetrate the mesh of the mesh body 12, and the plate material 20 is temporarily fixed with nuts 50 (plate material temporarily fixing process). The plate material 20 is attached to the rock bolts 14 by inserting the heads 15 of the rock bolts 14 into the through holes 21 and tightening with nuts. At this time, as shown in FIG. 2, the protrusions 26 of the plate material 20 are installed so as to penetrate the mesh of the mesh body 12. The nut 50 can be easily tightened by tightening the tightening head 62 of the tightening tool 60 while fitting it into the recesses 58 of the nut head 56.

[0057] Next, with the plate material 20 temporarily fixed, the interior of the bag body 32 of the filler member 30 is filled with a liquid filler material 36 that hardens over time (filler material injection process). The filler material 36 is injected into the bag body 32 through an injection port formed in the bag body 32 using an injection hose (not shown). This stabilizes the engagement and fixation state between the protrusions 26 of the plate material 20 and the mesh body 12. Thereafter, the nuts 50 are fully tightened using a tightening tool 60, applying the necessary tension to the lock bolts 14. The plate material 20 is fixed to the slope S (plate material fixing process). After fully tightening, the convex spherical seating surface 57 of the nut 50 abuts against the concave spherical nut support surface 24a of the plate material 20. The cylindrical portion 52 of the nut 50 enters the through-hole 21 of the plate material 20, leaving only the nut head 56 exposed above ground from the plate material 20. The mesh body 12 is pressed against the slope S by the plate material 20. After the nuts 50 are fully tightened, a sealing material may be filled into the recesses 58. This makes it possible to prevent rainwater from accumulating in the recesses 58.

[0058] As shown in Figure 1, when a rock bolt 14 is driven inclined from the perpendicular direction to a slope S, the axial direction of the nut 50 threaded onto the rock bolt 14 is inclined from the perpendicular direction to the flat surface (upper surface 22a) of the plate material 20 placed on the slope S. In the slope stabilization structure 10 using the nut 50 described above, the bearing surface 57 formed on the nut head 56 is formed in a convex spherical shape, so that the bearing surface 57 does not locally contact the nut support surface 24a of the plate material 20 but contacts the bearing surface 57 uniformly around the circumferential direction. This makes it possible to accommodate changes in the inclination angle of the rock bolt 14 even when the rock bolt 14 is inclined from the perpendicular direction to the slope S.

[0059] Furthermore, the cone-shaped raised portion 24 on the plate 20, i.e., the concave spherical nut support surface 24a on the inner surface of the raised portion 24, ensures a wider contact area with the convex spherical bearing surface 57 of the nut 50. This allows a wide range of inclination angles for the nut, regardless of the thickness of the plate. In other words, within the range of the concave spherical nut support surface 24a, localized concentrations of surface pressure acting on the bearing surface 57 and the nut support surface 24a are eliminated, preventing the nut 50 from sinking into the plate 20 and further preventing the nut 50 from loosening.

[0060] Furthermore, in the above-described slope stabilization structure 10, the cylindrical portion 52 of the nut 50, on which the female thread portion 54 is formed, is inserted into the through-hole of the plate material and is not visible from the ground side, so that the cylindrical portion 52 can ensure a sufficient thread allowance of the nut 50 while reducing the protruding length of the nut head 56 protruding from the plate material 20 to the ground side. This can improve the aesthetic appeal of the entire slope stabilization structure.

[0061] In particular, in this embodiment, the nut head 56 is formed in a substantially spherical shape, and this nut head 56 covers the head 15 of the lock bolt 14. Therefore, even if there is variation in the insertion direction of multiple rock bolts 14 driven into the slope S, the shape of the nut head as seen from the ground will be approximately the same spherical shape, as shown in Figure 1. This results in a structure that is excellent in appearance after installation. In addition, the nut 50 can prevent corrosion of the head 15 of the lock bolt 14.

[0062] Furthermore, the nut 50 of this embodiment has a female thread portion 54 extending from the cylindrical portion 52 to the nut head 56, and in the slope stabilization structure 10, the head 15 of the rock bolt 14 protrudes further above ground than the top of the raised portion 24 of the plate material 20, and this head 15 is screwed into the female thread portion 54 formed on the nut head 56. In this way, by increasing the protrusion length of the head 15 of the rock bolt 14 from the upper surface 22a of the plate material 20 and screwing the lock bolt 14 and the nut 50 together even in the area of ​​the nut head 56, a high fastening force can be obtained.

[0063] Furthermore, the mesh body 12 laid on the slope S has a higher ability to conform to the slope S and is easier to install than a concrete crest frame. In this way, in the slope stabilization structure 10 using the mesh body 12, unlike a concrete crest frame, the installation surface of the plate material 20 may not be flat. However, by providing the plate material 20 with a raised portion 24 and forming a raised nut support surface 24a, the influence of the unevenness of the slope S can be suppressed and good contact can be maintained between the nut support surface 24a and the seat surface 57 of the nut 50.

[0064] Furthermore, in the slope stabilization structure 10 of this embodiment, the mesh body 12 laid on the slope S can reliably prevent the occurrence of hole-out in the surface layer between adjacent rock bolts 14. Furthermore, by having the protrusions 26 of the plate material 20 penetrate the mesh of the mesh body 12, the protrusions 26 are caught on the mesh body 12, preventing the mesh body 12 from moving. This prevents the mesh body 12 from shifting out of position.

[0065] Next, other embodiments of the nut 50 will be described with reference to Figures 5 to 8. In the embodiments described below, the same reference numerals are used to designate parts corresponding to those in the above-described embodiments, and details of the same configurations will be omitted.

[0066] FIG. 5 shows another embodiment of the nut 50, where (a) is a side view, (b) is a plan view, and (c) is a bottom view. The nut 50 shown in FIG. 5 has a nut head 56 formed in a generally spherical shape as a whole and a tubular portion 52 protruding from the seating surface of the nut head 56. The nut head 56 has an upper portion forming a top surface and a lower portion forming a seating surface 57 formed in a convex spherical shape. In addition, between the top surface 56a and the seating surface 57, there is a peripheral surface portion 59 formed in a polygonal shape in a plan view. In this embodiment, the polygonal peripheral surface portion 59 is formed in a hexagonal shape, but is not limited to this and may be, for example, a quadrilateral shape.

[0067] By forming the peripheral surface 59 of the nut head 56 in a hexagonal shape in this way, tightening work can be performed by fitting an existing tightening tool 60 such as a torque wrench into this peripheral surface 59. Specifically, the nut 50 can be tightened with the peripheral surface 59 of the nut 50 fitted into a hexagonal receiving recess formed in the head of the tightening tool 60.

[0068] 6A and 6B are diagrams showing still another embodiment of the nut 50, with (a) being a side view and (b) being a plan view. Note that the bottom view of the nut 50 shown in Fig. 6 has the same shape as Fig. 4C, so it is not shown here.

[0069] The nut 50 shown in Figure 6 has a nut head 56 that is formed in a substantially hemispherical shape. A seating surface 57 formed at the bottom of the nut head 56 is formed in a convex spherical shape, and a top surface 56a of the nut head 56 is formed in a flat shape. A recess 58 into which a tightening tool 60 is fitted is formed in the center of the top surface 56a. In addition, a peripheral edge 46b of the top surface 56a is chamfered. As shown in Figure 6, the nut head 56 of the nut 50 of the present invention only needs to have a seating surface 57 that is convex spherical, and the overall shape of the nut head 56 does not have to be spherical.

[0070] FIG. 7 shows still another embodiment of the nut 50, where (a) is a cross-sectional view and (b) is a plan view.

[0071] The nut 50 shown in FIG. 7 , like the nut 50 shown in FIG. 4 , has a cylindrical portion 52, a spherical nut head 56, a female threaded portion 54 extending from the cylindrical portion 52 to the nut head 56, and a recessed portion 58 formed in the top surface 56a of the nut head 56. Furthermore, the nut 50 of this embodiment has a screw hole 53 connecting the recessed portion 58 and the female threaded portion 54. A flat head screw 64 is threaded into the screw hole 53 to seal the hole. The entire surface of the nut 50, including not only the outer surface but also the female threaded portion 54, the recessed portion 58, and the screw hole 53, is coated with a zinc plating layer. The provision of the screw hole 53 in this manner prevents air from accumulating (so-called air pockets) at the bottom of the recessed portion 58 or the female threaded portion 54 during hot-dip galvanizing (hot-dip galvanizing) of the nut surface, thereby preventing unplated portions from being generated.

[0072] 8A and 8B are diagrams showing still another embodiment of the nut 50, where (a) is a cross-sectional view and (b) is a plan view. The entire surface of the nut 50 is coated with a zinc plating layer.

[0073] The nut 50 shown in FIG. 8 has a cylindrical portion 52, a spherical nut head 56, a female thread 54 extending from the cylindrical portion 52 to the nut head 56, and a circular recess 58 formed in the top surface 56a of the nut head 56. Furthermore, a threaded hole 53 is formed between the recess 58 and the female thread 54, connecting them. Similar to the example shown in FIG. 7, the threaded hole 53 functions to prevent air pockets from forming when the nut 50 is hot-dip galvanized. A bolt 66 with a hexagonal head is threaded into the threaded hole 53. The galvanized layer can be formed by dipping the bolt in molten zinc. The nut 50 shown in FIG. 8 can be threaded onto the head 15 of the lock bolt 14 using a torque wrench (tightening tool 60).

[0074] FIG. 9 is a side view showing a first modified example of the nut 50. As shown in the example, the nut 50 may have a slit 55 extending in the axial direction on its side surface. This slit 55 is for checking the inclination angle of the lock bolt 14 relative to the vertical direction of the slope S, and one or more slits 55 are formed at least in the head of the nut 55. This slit 55 may be, for example, a recessed groove extending in the axial direction formed on the side surface of the nut 55. While FIG. 9 shows one slit 55, it is preferable that two or more slits 55 be formed at intervals in the circumferential direction, and more preferably three or more slits 55 be formed at equal intervals in the circumferential direction. Although not shown, the nut 50 shown in FIGS. 5 to 8 may have a slit 55 on the side surface of the area forming the bearing surface 57.

[0075] Figure 10 is a side view showing a second modified example of the nut 50. As shown by the dashed line in Figure 10, the cylindrical portion 52 of the nut 50 may have a female thread portion 54 on its upper inner circumferential surface and a hollow portion 54a on its lower inner circumferential surface where no thread grooves are formed. The hollow portion 54a and the thread grooves 54 are continuous. The lower region of the cylindrical portion 52 where the hollow portion 54a is formed is a protective region that protects the outer surface of the lock bolt 14 and prevents corrosion of the lock bolt 14 when the nut 50 is threaded onto the lock bolt 14.

[0076] Next, a modified example of the plate material 20 will be described with reference to FIGS. 11 and 12. The plate material 20 of this modified example has a longer diameter (length in the longer direction) in plan view that is larger than the meshes 13 of the mesh body 12, and has a generally hexagonal shape in plan view. The plate material 20 has, on its upper surface 22a, a first rib 23a formed along the periphery of the plate material 20 and a plurality of second ribs 23b extending radially from a central protrusion 24 toward the first rib 23a. A plurality of protrusions 26 are formed on the lower surface 22b of the plate material 20. The size of the plate material 20 in plan view can be set as appropriate, but may be, for example, 350 to 650 mm in the longitudinal direction, preferably 400 to 600 mm, and 150 to 450 mm in the width direction perpendicular to the longitudinal direction, preferably 250 to 400 mm.

[0077] 12 is a view of the plate material 20 placed on the mesh body 12, viewed from the side of the slope S (i.e., from the underside of the plate material 20). As shown in the example, the protrusions 26 of the plate material 20 are inserted into the mesh holes 13a of the mesh body 12, so that when an external force is applied to the mesh body 12 and the relative positions of the plate material 20 and the mesh body 12 tend to shift, the engagement structure between the protrusions 26 and the wire materials 13 can prevent the mesh body 12 from shifting in position.

[0078] (Second embodiment) Next, a second embodiment of the slope stabilization structure 10 will be described with reference to Fig. 13. In Fig. 13, the same components as those in the first embodiment shown in Fig. 2 are denoted by the same reference numerals. In the following description, only the components different from the first embodiment will be described in detail, and the description of the other components will be omitted.

[0079] In the slope stabilization structure 10 of this embodiment, the rock bolts 14 include a first rock bolt 14A and a second rock bolt 14B connected in series via a coupler 18. The coupler 18 is formed in a hollow cylindrical shape with a female thread formed on its inner circumferential surface. In the illustrated example, one end of the coupler 18 is threadedly engaged with the upper end of the first rock bolt 14A, and the other end of the coupler 18 is threadedly engaged with the lower end of the second rock bolt 14B. By using the coupler 18 to connect the two rock bolts 14A and 14B in this way, the length of the head 15 of each rock bolt 14 that protrudes from the slope S can be easily adjusted.

[0080] In this embodiment, the protective member 40 fills the gap between the grout 17 filled in the drilled hole 16 for the rock bolt 14 and the lower end surface of the nut 50. The protective member 40 is formed in a cylindrical shape surrounding the outer periphery of the rock bolt 14. The material of the protective member 40 is not particularly limited and can be a resin, a metal, or a combination thereof. However, it is preferably formed from a material that is at least axially compressible, such as an elastic material such as sponge. The cylindrical protective member 40 formed from sponge is preferably covered on its outer periphery with a water-stopping sheet or coating layer without holes. The protective member 40 may also be configured such that the sponge is filled with a filler such as cement paste or a rust inhibitor. Forming the protective member 40 from an elastic material such as sponge makes the protective member 40 axially compressible. Even if the length of the gap between the grout 17 and the nut 50 changes due to tightening of the nut 50, the protective member 40 can be compressed and deformed to appropriately fill the gap. In this way, by filling the gap with the protective member 40, corrosion of the lock bolt 14 can be prevented.

[0081] The protective member 40 of this embodiment includes a cylindrical sponge, a waterproof sheet covering the outer surface of the sponge, and a filler material filled within the sponge. The head 15 of the rock bolt 14 is inserted into the hollow portion of the cylindrical sponge whose outer surface is covered with the sheet, and then mortar filler is injected into the sponge. When the filler material is not yet hardened, a nut 50 is threaded onto the head 15 of the rock bolt 15, compressing the protective member 40 between the nut 50 and the grout material 17 in the drilled hole 16. The compressed filler material within the sponge can spill out of the sponge from both axial ends of the unwatertight sponge.

[0082] Next, a reference example of a slope stabilization structure 100 including a nut 70 having a convex spherical seat 77 and a plate member 20 will be described with reference to Fig. 14. In the slope stabilization structure 100 shown in Fig. 14, the same parts as those in the second embodiment of the slope stabilization structure 10 shown in Fig. 13 are designated by the same reference numerals, and their description will be omitted.

[0083] The nut 70 of the reference example is formed in a generally spherical shape overall, with a female screw portion 74 formed with a screw groove inside. A recess 78 is formed in the top surface of the nut 70 (i.e., the surface of the nut opposite the insertion opening of the anchor bolt 14) into which the tightening head 62 of a tightening tool 60 such as a torque wrench is fitted. Around the rock bolt 14, the gap area generated between the grout material 17 filled in the drilled hole 16 and the lower end surface of the nut 70 is filled with a tubular protective member 40 that surrounds the rock bolt 14.

[0084] Even if the nut 70 does not have a cylindrical portion as in this reference example, a sufficient thread allowance can be ensured by appropriately setting the diameter of the nut 70. Furthermore, by combining it with the plate material 20 having the raised portion 24, the contact area between the seat surface 77 and the nut support surface 24a can be increased, and the surface pressure of the nut support surface 24a that receives the axial force (fastening force) can be sufficiently ensured.

[0085] The present invention is not limited to the above-described embodiments and modifications, and various modifications are possible without departing from the spirit of the invention.

[0086] For example, the slope stabilization structure 10 according to the present invention may be a structure that does not include the mesh body 12 or the filler member 30. When the filler member 30 is disposed, the filler member 30 may be disposed between the slope S and the mesh body 12, or alternatively, between the mesh body 12 and the plate material 20. [Explanation of symbols]

[0087] 10 Slope stabilization structure 12 Net body 14 Rock Bolt 15 Rock bolt head 20 Plate material 22a Upper surface of plate 22b Bottom surface of plate material 24 Ridge 24a Nut support surface (nut support part) 26 Protrusion 30 Filling material 32 Bag body 34 Porous materials 36 Filling material 50 Nuts (lock bolt nuts) 52 Cylindrical part 54 Female thread part 56 Nut head 56a Top part 57 Seat 58 Recess 59 Peripheral part S slope (ground slope)

Claims

1. Rock bolts installed on the ground slope, a plate material installed on the ground slope and having a through hole through which the head of the rock bolt passes; a nut threaded onto the head of the rock bolt to fix the plate material to the ground slope, A protective member is provided which is disposed between the lower end surface of the nut and the grout material filled inside the drilled hole for the rock bolt and covers the outer periphery of the rock bolt; The nut is a nut head having a convex spherical seat that contacts the nut support portion of the plate material; a cylindrical portion protruding from the seat surface, having a screw groove on an inner circumferential surface into which the head of the lock bolt screws, and inserted into the through hole of the plate material; A slope stabilization structure characterized in that the protective member comprises a cylindrical sponge surrounding the outer periphery of the rock bolt and a time-hardening filler filled within the sponge.

2. 2. The slope stabilization structure according to claim 1, wherein the nut support portion is formed by raising the periphery of the through hole on the upper surface side of the plate material, and the inner surface of the raised portion is made into a concave spherical nut support surface that receives the convex spherical seat surface of the nut.

3. 3. The slope stabilization structure according to claim 1, wherein the heads of the rock bolts protrude above the upper surfaces of the plates when the plate is installed on the ground slope.

4. 4. The slope stabilization structure according to claim 1, wherein the nut head is formed in a substantially spherical shape to cover the head of the lock bolt.

5. 5. The slope stabilization structure according to claim 1, wherein the nut head has a recess in the top surface thereof into which a tightening tool is fitted.

6. The slope stabilization structure according to any one of claims 1 to 4, characterized in that the nut head has a peripheral surface portion formed in a polygonal shape in a planar view between the top surface portion and the seat surface.

7. a mesh body laid on the ground slope and pressed against the ground slope by the plate material; 7. The slope stabilization structure according to claim 1, wherein the plate material has protrusions that protrude from the lower surface and penetrate the mesh of the mesh body.

Images