Anchor structures, preventive or protective facilities, and construction methods for anchor structures.

Abstract

To provide an anchor structure capable of using a more flexible configuration for the required proof stress when a load is held by a plurality of anchors to support or hold the structure.SOLUTION: Since anchors having different standards can be used by connecting a plurality of anchors (anchors 11a, anchors 11b) in series by a connecting member 12, and holding a load F by the plurality of anchors connected in series, an anchor structure 1 can use a configuration that is more flexible with respect to the required proof stress.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an anchor structure, a preventive or protective facility, and a construction method of the anchor structure.

Background Art

[0002] Anchors are widely used as fixing means for supporting or holding structures. For example, as a protective or preventive facility against avalanches and falling rocks, a fence (including those with wire meshes) or a triangular pyramid-shaped frame is installed on a slope where there is a risk of avalanches and falling rocks, and these fences or frames are suspended by a suspension rope (wire rope) from an anchor fixed above the slope, or a wire rope of a pocket-type lock net stretched to form a pocket on a slope where there is a risk of avalanches and falling rocks, or a wire rope of a covering-type lock net, or a facility suspended by an anchor fixed above the slope, or a facility in which a floating rock pressing rope is laid along the slope and the upper part of the rope is suspended by an anchor, etc. are known. Technologies related to such protective facilities and anchors installed on slopes are disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The load-bearing capacity (the load an anchor can hold) can generally be increased with larger anchors, but installing large-diameter anchors requires large machinery. Large-diameter anchors are necessary when the load on the anchor is heavy or when the anchor's load-bearing capacity is reduced due to soft ground, etc. However, installing large-diameter anchors is difficult on slopes or other areas where large machinery cannot be brought in, and in such cases, multiple small-diameter anchors are installed in parallel to obtain the required load-bearing capacity. For example, as shown in Figure 7 of Patent Document 1, a single frame is suspended by two anchors installed in parallel. When using two anchors installed in parallel in this way to obtain the load-bearing capacity of two anchors, anchors of the same specifications are used from the viewpoint of equalizing the load balance. For example, if there are anchors with load-bearing capacities of 15KN, 20KN, and 40KN, and the required load-bearing capacity is 50KN, two 40KN anchors would have to be used, which would be over-specified for the requirements and would be uneconomical.

[0005] In view of the above, the present invention aims to provide an anchor structure that allows for a more flexible configuration to be used in relation to the required load-bearing capacity when a load is supported or held by multiple anchors for the purpose of supporting or holding a structure. [Means for solving the problem]

[0006] (Composition 1) An anchor structure characterized by having multiple anchors connected in series, thereby holding a load with these multiple anchors connected in series.

[0007] (Configuration 2) The anchor structure according to Configuration 1, characterized in that, when a load is applied to the anchor structure, the load is applied to all of the anchors connected in series before the displacement of any one of the anchors connected in series exceeds a specified displacement of that anchor.

[0008] (Composition 3) The anchor structure according to configuration 1 or 2, characterized in that the maximum load-bearing capacity of the anchor structure is obtained by the sum of the load-bearing capacities of all anchors connected in series.

[0009] (Composition 4) The anchor structure according to configuration 3, characterized in that when the maximum load-bearing capacity of the anchor structure is generated, the displacement amount of each of the multiple anchors connected in series becomes the specified displacement amount of each anchor.

[0010] (Composition 5) An anchor structure according to any one of configurations 1 to 4, wherein the anchor has a connecting member for connecting the anchors, and the connecting member is equipped with a length adjustment mechanism.

[0011] (Composition 6) An anchor structure according to any one of configurations 1 to 5, characterized in that anchors of different specifications are connected in series.

[0012] (Composition 7) An anchor structure according to any one of configurations 1 to 6, characterized in that, among the multiple anchors connected in series, the load is first applied to the anchor with the largest specified displacement.

[0013] (Composition 8) The anchor structure according to configuration 7, characterized in that the multiple anchors connected in series are connected in the order in which the load is applied, from the anchor with the largest specified displacement to the anchor with the smallest displacement.

[0014] (Composition 9) An anchor structure according to any one of configurations 1 to 6, characterized in that the load is applied first to the anchor with the largest diameter among the multiple anchors connected in series.

[0015] (Composition 10) The anchor structure according to Configuration 9, wherein a plurality of anchors connected in series are connected from an anchor with a larger diameter to an anchor with a smaller diameter in the order in which a load is applied.

[0016] (Configuration 11) The anchor structure according to any one of Configurations 1 to 10, further comprising a connecting member for connecting the anchors, wherein the connecting member has a displacement difference absorption structure that absorbs a displacement difference, which is a difference in a specified displacement amount between adjacent anchors.

[0017] (Configuration 12) The anchor structure according to Configuration 11, wherein the connecting member has a play for the displacement difference by the displacement difference absorption structure.

[0018] (Configuration 13) The anchor structure according to Configuration 11 or 12, wherein the connecting member includes a length adjustment mechanism and a reference portion for measuring an amount of length adjustment.

[0019] (Configuration 14) The anchor structure according to any one of Configurations 1 to 13, wherein the plurality of anchors are connected in series along a direction in which a load is applied.

[0020] (Configuration 15) A preventive or protective facility supported by the anchor structure according to any one of Configurations 1 to 14 and installed on a sloping ground.

[0021] (Configuration 16) A construction method of an anchor structure connected in series, comprising: a step of driving an anchor; and a step of connecting the anchors in series while applying a load to the anchors in a direction in which a load to be held by the anchors is applied.

[0022] (Configuration 17) A method for constructing an anchor structure according to configuration 16, characterized in that the anchor is connected by a connecting member having a length adjustment mechanism, and the length of the connecting member is shortened by the length adjustment mechanism until at least the looseness is eliminated.

[0023] (Composition 18) The method for constructing an anchor structure according to configuration 17, characterized in that the connecting member is equipped with a play mechanism, and after the step of shortening the length of the connecting member, a step of providing the connecting member with play equal to the difference in displacement, which is the difference in the specified amount of displacement between adjacent anchors.

[0024] (Composition 19) A preventive or protective facility comprising an anchor structure as described in any of configurations 1 to 14, a plurality of support columns, a receiving member provided between the support columns, and a support column connecting member connecting any of the plurality of anchors to the support column.

[0025] (Composition 20) The prevention or protection facility according to configuration 19, characterized in that the prevention or protection facility is installed on a sloping ground, and the support column is connected to one of the plurality of anchors located on the slope above the support column by the support column connecting member.

[0026] (Composition 21) The prevention or protection facility according to configuration 20, characterized in that one of the plurality of anchors connected to the support column is driven perpendicularly to the slope.

[0027] (Composition 22) The prevention or protection facility according to configuration 21, characterized in that one of the plurality of anchors connected to the support column and the support column connecting member are arranged in a straight line.

[0028] (Composition 23) The prevention or protection facility according to any one of claims 19 to 22, characterized in that the connection position of the support column connecting member to the support column is between the upper end of the support column and half the height of the support column. [Effects of the Invention]

[0029] According to the anchor structure of the present invention, by connecting multiple anchors in series, it becomes possible to use a more flexible configuration for the required load-bearing capacity. [Brief explanation of the drawing]

[0030] [Figure 1] Side view showing an anchor structure according to Embodiment 1 of the present invention [Figure 2] Perspective view showing the anchor structure of Embodiment 1 [Figure 3] Conceptual diagram comparing a conventional anchor with the anchor structure of Embodiment 1. [Figure 4] Table showing experimental results of the anchor structure of Embodiment 1 [Figure 5] A photograph showing the experiment. [Figure 6] A conceptual diagram illustrating the state in which a load is applied to a series anchor, causing displacement. [Figure 7] Side view showing the anchor structure of Embodiment 2 [Figure 8] Perspective view showing the anchor structure of Embodiment 2 [Figure 9] Conceptual diagram showing the construction procedure for the anchor structure of Embodiment 2 [Figure 10] A conceptual diagram illustrating the state in which a load is applied to a series anchor, causing displacement. [Figure 11] Table explaining the use of anchors with different specifications. [Figure 12] Table showing experimental results of the anchor structure of Embodiment 2 [Figure 13] Diagram showing another example of an anchor structure [Figure 14] This diagram shows an example of using an anchor structure for rockfall protection posts. [Figure 15]This diagram shows an example of using an anchor structure for rockfall protection posts. [Figure 16] Schematic side view showing the rockfall protection fence of Embodiment 3 [Figure 17] Schematic plan view showing the anchor structure portion of the rockfall protection fence of Embodiment 3 [Figure 18] Conceptual diagram illustrating the load-bearing capacity of anchor structures used in protective fences. [Figure 19] A schematic side view showing another example of a rockfall protection fence. [Figure 20] Schematic side view showing an example of a support column connecting member. [Figure 21] Diagram illustrating a conventional structure with two anchors installed in parallel. [Modes for carrying out the invention]

[0031] The embodiments of the present invention will be described in detail below with reference to the drawings. Note that the following embodiments are merely examples of how the present invention can be implemented, and do not limit the present invention to their scope.

[0032] <Embodiment 1> Figure 1 is a side view showing an anchor structure of Embodiment 1 according to the present invention, and Figure 2 is a perspective view thereof (cover members 14a and 14b are not shown for the sake of visibility of the members). The anchor structure 1 of this embodiment is an anchor that is driven into the ground to support a load in order to hold a facility on a slope or the like, and the load is held by multiple anchors connected in series. In this embodiment, multiple anchors are connected in series along the direction in which the load is applied. The anchor structure 1 comprises anchors 11a and 11b, a connecting member 12 for connecting these two anchors, and mounting portions 13a and 13b.

[0033] Anchors 11a and 11b are pipe anchors formed from steel pipes, and cap members 14a and 14b are provided on the top of each anchor. In addition to their function as caps, the cap members 14a and 14b also function as retainers for the attachment parts 13a and 13b and for preventing cables, etc., connected to the anchor structure 1 (cables, etc., that connect to facilities whose loads are held by the anchor structure 1) from coming loose. Although not shown in the illustration, holes are formed in the tops of anchors 11a and 11b and in the cap members 14a and 14b for passing retaining pin bolts, and they are fastened together by pin bolts. The anchor structure 1 of this embodiment uses anchors with the same specified displacement. The "specified displacement" is the amount of displacement at which the anchor generates its maximum load-bearing capacity. The specified displacement is determined by the size (thickness and length) of the anchor and the ground conditions such as the bearing capacity of the ground at the site where the anchor is installed. The method of determining the "specified displacement" is arbitrary and can be anything from measuring it on-site, experimentally determining it by simulating the target conditions, or calculating it.

[0034] Mounting portions 13a and 13b are components for attaching the connecting member 12 to anchors 11a and 11b, and have a ring-shaped portion that fits on the outside of the anchor and a fastening portion that protrudes from the ring-shaped portion. The fastening portion has a hole for passing a pin bolt PB through, and is fastened with the connecting member 12 and the pin bolt PB.

[0035] The connecting member 12 includes a steel arm 124 and a turnbuckle 121. The turnbuckle 121 functions as a length adjustment mechanism. Holes for passing pin bolts PB are formed at both ends of the steel arm 124, and the steel arm 124 is connected to the turnbuckle 121, and the steel arm 124 is connected to the mounting part 13a, respectively, by the pin bolts PB.

[0036] Next, we will explain the construction procedure for anchor structure 1. First, anchors 11a and 11b are installed. Any method can be used to install the pipe anchors 11a and 11b, but for example, the method disclosed in Patent Document 1 can be used. The equipment used in the method disclosed in Patent Document 1 is equipment that can be transported by hand, so anchors can be installed even in places where large machinery cannot be brought in.

[0037] Next, the anchor 11a and anchor 11b are connected in series using the connecting member 12. The order in which the connecting member 12 is attached to the anchors 11a and 11b can be arbitrary. For example, the steel arm 124, turnbuckle 121, and mounting parts 13a and 13b may be temporarily assembled first and then attached to the anchors 11a and 11b, or the mounting parts 13a and 13b may be attached to the anchors 11a and 11b first, and then the steel arm 124 and turnbuckle 121 may be attached. After assembling each component, the length of the connecting component 12 is shortened by rotating the turnbuckle 121, thereby applying tension until at least the looseness between each component is eliminated. "Looseness between components" refers to the combined result of tolerances and play between each component, such as the difference between the inner diameter of the hole (perforation) drilled in the ground for installing the anchor and the outer diameter of the anchor, the hole tolerance of each pin bolt, the play in the turnbuckle threads, and the difference between the inner diameter of the mounting part and the outer diameter of the anchor. The turnbuckle is used to apply tension to eliminate the looseness caused by these tolerances and play. The anchor structure 1 is constructed by fastening a cable (not shown in particular) to the anchor for connecting to a facility whose load will be held by the anchor structure 1, and then attaching the cover members 14a and 14b to the anchors 11a and 11b.

[0038] Furthermore, tightening the turnbuckle 121 will cause a force to act in a direction that pulls anchors 11a and 11b towards each other. As a result, the play between the anchor and the drill on the opposite side of the anchor tends to increase. For example, when a load is applied in the direction of F in Figure 1 during the use of the anchor structure 1, if there is play between the anchor and the drill on the left side of anchor 11a, sufficient load-bearing capacity may not be obtained in the initial stages when the load is applied. To mitigate these problems, it is advisable to connect the anchors while applying the load to them in the direction in which the load they are supposed to hold is applied. In the example shown in Figure 1, it is preferable to apply a load to anchor 11a in the direction of F before applying tension with the turnbuckle, and then tighten the turnbuckle 121 in this state. The load applied should be such that, when tension is applied with the turnbuckle, anchor 11a (an anchor whose direction of application of the load it should hold is opposite to the direction of tightening the turnbuckle) does not move in the direction of tightening the turnbuckle. Any method can be used to apply the load.

[0039] An example of a construction method in which a load is applied to anchor 11a while tightening the turnbuckle 121 is as follows. 1. Apply a load of 1KN or more to anchor 11a (the anchor that receives the load first) to eliminate any gap or looseness in front of the load (the play between the anchor and the drilled hole on the left side of anchor 11a in Figure 1). 2. Connecting member 12 connects anchor 11a and anchor 11b, and by tightening turnbuckle 121, tension is applied so that anchor 11a is momentarily pulled in the direction of anchor 11b (a state in which the front and rear anchors are balanced: the front anchor is momentarily pulled in the direction of the rear anchor, but fine adjustments are made to return the front anchor to its original position (the position when the load was applied) so that there is no displacement), thereby eliminating the forward looseness of anchor 11b (the play between the anchor and the drill on the left side of anchor 11b in Figure 1). The above construction method allows both anchors to eliminate wobbling by applying the same initial tension. Furthermore, to eliminate rattle (such as loosening of anchors or play in individual components), it is preferable to apply a load of 1 kN or more. On the other hand, since it is undesirable for the anchors to be displaced by applying too much load, it is preferable to apply a load of 5 kN or less. However, these values ​​are not limited to these ranges, and may be adjusted as appropriate depending on the size of the anchors and the condition of the ground.

[0040] According to the anchor structure 1 of this embodiment, by connecting the anchors in series, it becomes possible to use a more flexible configuration for the required load-bearing capacity. Figure 3 shows a conceptual diagram comparing a conventional anchor (parallel connection) with the anchor structure 1 of this embodiment. In the case of two conventionally placed anchors in parallel, it is necessary to use anchors of the same specifications to equalize the load balance. For example, if there are anchors with load capacities of 15kN, 20kN, and 40kN, and the required load capacities are 50kN, then two 40kN anchors (11') would have to be used, resulting in over-specification and being uneconomical. In contrast, the anchor structure 1 of this embodiment allows the use of anchors 11a and 11b with energies of 15kN and 40kN, respectively. As can be seen from this, the anchor structure 1 of this embodiment can be configured very flexibly, thereby providing high cost-effectiveness.

[0041] Figure 4 is a table showing the experimental results for the anchor structure of Embodiment 1. Figure 5 is a photograph showing the experimental setup. The table on the left of Figure 4 shows the specifications of the anchors used in this experiment (anchor diameter, length, and displacement under load). Here, anchor 11a was a pipe anchor with a diameter of 89.1 mm, a length of 1.1 m, and a yield strength of 25 kN (displacement of 55 mm), and anchor 11b was a pipe anchor with a diameter of 139.8 mm, a length of 1.1 m, and a yield strength of 35 kN (displacement of 55 mm). In this experiment, as explained above, the anchors were connected to each other while applying a load to the anchors in the direction in which the load they should hold is applied. More specifically, with a load of 1 kN applied to anchor 11a, the turnbuckle 121 was tightened to a state in which anchor 11a was momentarily pulled in the direction of anchor 11b (a state in which the front and rear anchors are balanced: the front anchor is momentarily pulled in the direction of the rear anchor, but the front anchor is returned to its original position (the position when the load was applied) by making fine adjustments such as slightly loosening the turnbuckle 121 to prevent displacement). The table on the right side of Figure 4 shows the experimental results. When a load of 5kN was applied, the displacement of both anchors was 3mm, confirming the synchronization of anchor displacement. As described above, since both anchors were connected with tension using the connecting member 12 during construction, the displacement amounts of both anchors remain synchronized even with subsequent loads. The maximum load-bearing capacity obtained was 60kN, which is the sum of the maximum load-bearing capacities of both anchors, and it was confirmed that the displacement at that time was 55mm.

[0042] In this embodiment, the anchor structure 1 synchronizes the displacement amounts of anchors 11a and 11b, so that "when a load is applied to the anchor structure, the load is applied to all anchors connected in series before the displacement amount of any one of the anchors connected in series exceeds the specified displacement amount of that anchor." Furthermore, the anchor structure 1 of this embodiment is such that "the maximum load-bearing capacity of the anchor structure is obtained by the sum of the load-bearing capacities of all anchors connected in series." As shown in the conceptual diagram in Figure 6(b), if the anchors are not properly connected, such as when the connecting members are loose, some anchors will not generate any load-bearing capacity. In the state shown in Figure 6(b-1), anchor C does not generate any load-bearing capacity at all. In this state, if anchors A and B exceed the specified displacement amount (i.e., exceed the load-bearing capacity), then anchors A and B will no longer be able to generate the specified load-bearing capacity. That is, in the state shown in Figure 6(b-2) as the displacement progresses further, anchor C is generating load-bearing capacity, but anchors A and B are unable to generate the specified load-bearing capacity. As a result, the load-bearing capacity of the anchor structure cannot be obtained as the sum of the load-bearing capacities of all anchors connected in series. In contrast, as shown in the conceptual diagram in Figure 6(a), when each anchor is properly connected, the load is distributed to all anchors connected in series when a load is applied, and the load-bearing capacity of the anchor structure is obtained as the sum of the load-bearing capacities of all anchors connected in series. The system is designed so that, when a load is applied to the anchor structure, all anchors connected in series are subjected to the load before the displacement of any one of the anchors exceeds the specified displacement of that anchor. This configuration ensures that all anchors can generate load-bearing capacity against the load. The effect is maximized when all anchors are connected in such a way that they simultaneously generate their maximum load-bearing capacity, but it is acceptable if some anchors do not generate their maximum load-bearing capacity, as long as the required load-bearing capacity is satisfied. The condition that "all anchors generate maximum load capacity simultaneously" is achieved by ensuring that "when the maximum load capacity of the anchor structure is generated, the displacement of each of the multiple anchors connected in series equals the specified displacement of each anchor."

[0043] As described above, according to the anchor structure 1 of this embodiment, by connecting the anchors in series, it is possible to use anchors of different specifications, allowing for a more flexible configuration to meet the required load-bearing capacity. This also makes it possible to achieve high cost-effectiveness. Furthermore, it has a length adjustment mechanism to eliminate play and tolerances between each component, so that the displacement of the anchor when a load is applied is synchronized, and problems such as not being able to obtain the planned load-bearing capacity can be reduced. Furthermore, when installing anchors, if the anchors are connected to each other while applying a load in the direction in which the load they are supposed to hold is applied, it is possible to reduce the occurrence of problems such as not being able to obtain the expected load-bearing capacity in the initial stages when a load is applied.

[0044] Furthermore, conventional parallel-connected anchors sometimes suffered from problems where the required load-bearing capacity could not be obtained due to the accumulation of soil and sediment, but the anchor structure 1 of this embodiment can reduce the occurrence of such problems. Figure 21 shows an example of a conventional parallel-connected anchor configuration. In this configuration, when using two anchors 106 and 107 installed in parallel, a double rope 101 is used and connected to the main rope 102. The connection between the double rope 101 and the main rope 102 involves engaging a shackle 104 with the thimble 103 of the main rope 102, and passing the double rope 101 through the shackle 104. A ring-shaped member 105 is loosely fitted to the shackle shaft of the shackle 104, and the double rope 101 is wrapped around the outer circumference of this ring-shaped member 105. This configuration allows the anchors to be suspended by the double rope via a pulley, ensuring that the load is evenly distributed to the two parallel-installed anchors 106 and 107. However, due to aging deterioration or the volume of soil, the pulley may cease to function properly, sometimes resulting in a large load being placed on only one of the anchors. Furthermore, when two anchors installed in parallel as described above are suspended by a double rope 101, sufficient load-bearing capacity (the load-bearing capacity of two anchors) may not be obtained due to the effects of unevenness in the sloping ground. For example, due to the effects of slope undulations and accumulated sediment, only one side of the double rope 101 may come into contact with the unevenness, resulting in a load imbalance and a large load being placed on only one anchor. As described above, in the case of parallel connection types, it becomes impossible to apply the load evenly to the parallel anchors, which can result in a failure to obtain the required load-bearing capacity. However, with the anchor structure 1 of this embodiment, such problems are reduced.

[0045] <Embodiment 2> Figure 7 is a side view showing the anchor structure of Embodiment 2 according to the present invention, and Figure 8 is a perspective view thereof (the cover members 14a and 14b are not shown for the sake of clarity of the members). Note that components similar to those in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and their explanations here are omitted or simplified. The anchor structure 1' of this embodiment is similar in basic concept to the anchor structure 1 of Embodiment 1, but further has a configuration for using anchors with different specified displacement amounts. As a "configuration for using anchors with different specified displacement amounts," the anchor structure 1' of this embodiment is equipped with a displacement difference absorbing structure 122 in the connecting member 12'.

[0046] The displacement difference absorption structure 122 includes a steel arm 1221 and a steel arm 1222. The steel arm 1222 has holes formed at both ends for passing pin bolts PB through, and the steel arm 1222 and the turnbuckle 121, and the steel arm 1222 and the steel arm 1221 are connected by pin bolts PB. The steel arm 1221 has a hole formed at one end for passing a pin bolt PB to connect to the mounting portion 13a. At the other end, an elongated hole 1221H is formed for loosely fitting the pin bolt PB to connect the steel arm 1221 so that it can slide in the direction of the load. The displacement difference absorbing structure 122 is configured such that a pin bolt PB is loosely fitted into an elongated hole 1221H of the steel arm 1221 so as to be slidable in the direction of the load, thereby connecting the steel arm 1222 to the steel arm 1221 in a slidable manner. The elongated hole 1221H is formed as an elongated hole having a length greater than or equal to the difference between the specified displacement of anchor 11a and the specified displacement of anchor 11b. This allows the steel arm 1222 to slide relative to the steel arm 1221 by at least the difference between the specified displacement of anchor 11a and the specified displacement of anchor 11b.

[0047] The anchor structure 1' further includes nuts 123a and 123b, which serve as reference points for measuring the length adjustment amount.

[0048] Next, the construction procedure for anchor structure 1' will be explained with reference to Figure 9. First, anchors 11a and 11b are installed (Figure 9(a)). In this embodiment, as will be explained later, anchor 11a has a specified displacement of 80 mm, and anchor 11b has a specified displacement of 55 mm. The method for installing the anchors is the same as described in Embodiment 1. Next, a facility to be suspended by the anchor structure 1' (in this case, a suspended avalanche prevention fence HF) is attached to the anchor 11a (Figure 9(b)). This applies a load to the anchors, as explained in Embodiment 1, which is to "connect the anchors while applying a load to the anchors in the direction in which the load that the anchors should hold is applied." Next, the anchors 11a and 11b are connected in series using the connecting member 12'. When attaching the connecting member 12' to the anchors 11a and 11b, the order in which the members are assembled can be arbitrary, as described in Embodiment 1. After assembling each component, the length of the connecting member 12' is shortened by rotating the turnbuckle 121, thereby applying tension until at least the looseness between each component is eliminated (Figure 9(c)). This is the same concept as in Embodiment 1. That is, with the load of the suspended avalanche prevention fence HF (approximately 5KN in this case) applied to the anchor 11a, the turnbuckle 121 is tightened to a state in which the anchor 11a is momentarily pulled in the direction of the anchor 11b (a state in which the front and rear anchors are balanced: the front anchor is momentarily pulled in the direction of the rear anchor, but the front anchor is returned to its original position (the position when the load was applied) by making fine adjustments such as slightly loosening the turnbuckle 121 so as not to cause displacement). As a result, the tension on the main rope connecting the suspended avalanche prevention fence HF and the anchor 11a and the tension on the connecting member 12' are synchronized (initial tension synchronization is performed).

[0049] After tightening the turnbuckle 121, loosen the turnbuckle 121 by the difference between the specified displacement of anchor 11a and the specified displacement of anchor 11b (25 mm) to create play in the length of the connecting member 12' (Figure 9(d)). In other words, by loosening the turnbuckle 121, the pin bolt PB of the steel arm 1222 slides back into the elongated hole 1221H of the steel arm 1221 by the length that has been increased, creating 25 mm of play. When loosening the turnbuckle 121 to create play, nuts 123a and 123b are used to ensure the exact length of that play. By measuring the distance between nuts 123a and 123b when tightening the turnbuckle 121, and then measuring the distance between nuts 123a and 123b as they expand when the turnbuckle 121 is loosened, the amount of play can be accurately measured. When tightening the turnbuckle 121, rotating nuts 123a and 123b until they contact the turnbuckle body ensures that the gap between nuts 123a and 123b and the turnbuckle body when the turnbuckle 121 is loosened is equal to the play length, which is convenient for subsequent maintenance and management. Furthermore, since it is sufficient to measure the distance between nuts 123a and 123b before and after loosening the turnbuckle 121, the positions of nuts 123a and 123b can be arbitrary. Here, nuts 123a and 123b are used as reference points for measuring the length adjustment amount, but any mark may be used instead of nuts. Furthermore, in a configuration where the length is adjusted by a screw mechanism, as in this embodiment, the amount of length adjustment can be defined by the number of rotations or angle of the screw, based on the screw pitch. Therefore, even without providing a reference part for measuring the amount of length adjustment, it is possible to accurately set the amount of play by the number of rotations or angle when loosening the turnbuckle 121.

[0050] Finally, the anchor structure 1 is constructed by attaching the cover members 14a and 14b to the anchors 11a and 11b (the cover members 14a and 14b may be attached at any time when it is possible to attach them).

[0051] The anchor structure 1' of this embodiment connects anchors with different specified displacement amounts in series. In order for each anchor to exert its maximum load-bearing capacity simultaneously, it is necessary to ensure that the specified displacement amounts that produce the maximum load-bearing capacity of each anchor occur simultaneously. In other words, for example, when connecting three standard anchors shown in the table in Figure 11(a) in series, if each anchor is connected without any play as in Figure 6(a), the displacement of all anchors will be the same. As a result, as shown in Figure 11(b), when the displacement exceeds 5 cm, the 89.1φ pipe anchor exceeds its load-bearing capacity and can no longer be considered to function as an anchor. The same applies to the 114.3φ pipe anchor when the displacement exceeds 7 cm. As a result, the overall load-bearing capacity of the anchor structure is limited to a maximum of 65 kN. On the other hand, by connecting anchors from those with larger specified displacement amounts to those with smaller specified displacement amounts in the order in which the load is applied, and by providing a displacement difference absorption structure 122 that absorbs the difference in displacement amounts between adjacent anchors, the load-bearing capacity can be maximized. For example, as shown in the conceptual diagram in Figure 10, when connecting three standard anchors shown in Figure 11(a) in series, let A be a 139.8φ pipe anchor with a specified displacement of 10cm, B be a 114.3φ pipe anchor with a specified displacement of 7cm, and C be an 89.1φ pipe anchor with a specified displacement of 5cm. The anchors are then connected in order of load application, from the largest to the smallest specified displacement. Furthermore, the play in the displacement difference absorption structure 122 between anchors A and B is set to 3cm, and the play in the displacement difference absorption structure 122 between anchors B and C is set to 2cm (Figure 10(a)). As a result, from the start of the load until the displacement reaches 3 cm, only anchor A generates load-bearing capacity and causes displacement due to the play in the displacement difference absorption structure 122 between anchors A and B (Figure 10(a-1)). If the load increases further, the play in the displacement difference absorption structure 122 between anchors A and B disappears, causing displacement in anchor B and generating load-bearing capacity. Until the displacement reaches 5 cm, the play in the displacement difference absorption structure 122 between anchors B and C allows anchors A and B to generate load-bearing capacity, but anchor C does not (Figure 10(a-2)). As the load increases further, the play in the displacement difference absorption structure 122 between anchors B and C disappears, and all anchors A to C generate load-bearing capacity (Figure 10(a-3)). As shown in the table in Figure 11(c), anchors A to C generate load-bearing capacity with a time difference until the displacement reaches 5 cm, and after the displacement exceeds 5 cm, all anchors generate load-bearing capacity. When the displacement reaches 10 cm, the displacement of anchor A is 10 cm, anchor B is 7 cm, and anchor C is 5 cm, generating load-bearing capacity of 40 kN for anchor A, 25 kN for anchor B, and 15 kN for anchor C, resulting in a maximum load-bearing capacity of 80 kN for the anchor structure as a whole. As explained above, the load-bearing capacity of the anchor structure is maximized by connecting anchors in order of increasing displacement to decreasing displacement, and by providing a gap equivalent to the difference in displacement between adjacent anchors. However, the order of anchor connection and the method of providing the gap may differ from the above, as long as the required load-bearing capacity is satisfied.

[0052] Figure 12 is a table showing the experimental results for the anchor structure of Embodiment 2. The table on the left of Figure 12 shows the specifications of the anchors used in this experiment (anchor diameter, length, and displacement under load). Here, anchor 11a was a pipe anchor with a diameter of 114.3 mm, a length of 1.6 m, and a yield strength of 35 kN (displacement of 80 mm), and anchor 11b was a pipe anchor with a diameter of 89.1 mm, a length of 1.1 m, and a yield strength of 25 kN (displacement of 55 mm). The table on the right side of Figure 12 shows the experimental results. Until the displacement reaches 25 mm, only anchor 11a generates load-bearing capacity due to the play in the displacement difference absorption structure 122. When the displacement exceeds 25 mm, both anchor 11a and anchor 11b generate load-bearing capacity. The maximum load-bearing capacity obtained was 60kN, which is the sum of the maximum load-bearing capacities of both anchors, and it was confirmed that the displacement at that time was 80mm (displacement of anchor 11a: 80mm, displacement of anchor 11b: 55mm).

[0053] As can be understood from the above explanation, the anchor structure 1' of this embodiment is configured such that "the load is applied first to the anchor with the largest specified displacement among a plurality of anchors connected in series," and "the plurality of anchors connected in series are connected from the anchor with the largest specified displacement to the anchor with the smallest displacement in the order in which the load is applied." Furthermore, "the load is applied first to the anchor with the largest diameter among a plurality of anchors connected in series," and "the plurality of anchors connected in series are connected from the anchor with the largest diameter to the anchor with the smallest diameter in the order in which the load is applied."

[0054] According to the anchor structure 1' of this embodiment, the same effects as in Embodiment 1 can be obtained even when using anchors with different specified displacement amounts.

[0055] Although each embodiment uses two anchors as an example, as mentioned in the above description, the method can also be applied when connecting three or more anchors. Furthermore, although pipe anchors were used as examples in each embodiment, any type of anchor can be used, and the direction of installation (vertical direction, direction perpendicular to the slope, etc.) can be appropriately selected depending on the type of anchor.

[0056] The connecting member can connect the anchors in series and has the necessary rigidity against tensile load (rigidity that does not substantially affect the synchronization of the displacement amounts of each anchor as described above), and is not limited to the configuration of the connecting member described in each embodiment. For example, a wire rope may be used as the connecting member. When using a wire rope, pretensioning may be performed to remove the structural elongation of the rope in order to obtain the necessary rigidity against tensile load. In the case of wire ropes, there is a degree of freedom in how they bend, so the bending of the wire rope may be used as an alternative to the displacement difference absorption structure described in the embodiment. Furthermore, if the elongation of a component can be controlled under tension, that elongation may be used as the "play equivalent to the difference in specified displacement" as described above. For example, the elongation of the wire rope may be taken into account, and the wire rope may be allowed to sag (the sum of the rope's elongation and sag forms the "difference in specified displacement"). As is clear from the above explanation, the "displacement difference absorption structure" is not limited to the configuration of Embodiment 2, but can be any configuration that can function as a margin of error corresponding to the difference in the specified displacement amount. Furthermore, while each embodiment uses a screw mechanism (a turnbuckle as a specific example) to adjust the length of the connecting member, the present invention is not limited to this, and any mechanism capable of length adjustment can be adopted.

[0057] Figure 13 shows another example of a connecting member. Figure 13(a) is a top view, and Figure 13(b) is a side view with a portion of it shown transparently. The connecting member used in the anchor structure 1'' in Figure 13 has some differences in its specific structure from that described in the embodiment, but conceptually it is the same as that described in the embodiment. For components similar to those in the embodiments, the same reference numerals as in the embodiments are used, and their descriptions here are omitted or simplified. The anchor structure 1'' in Figure 13 includes a turnbuckle 121 as a length adjustment mechanism and steel arms 122''a and 122''b as displacement difference absorption structures as connecting members. Each of the cover members 14a'' and 14b'' has a mounting portion (bolt B) for attaching the connecting members. Holes are formed in the upper parts of anchors 11a and 11b and in the cover members 14''a and 14''b, respectively, for passing retaining pin bolts, and they are fastened together by the pin bolts. Steel arms 122'a and 122'b have similar configurations, with a hole formed at one end for passing a pin bolt PB to connect to the turnbuckle 121. At the other end, elongated holes 122'Ha and 122'Hb are formed for slidably fitting the mounting parts (bolts B) of the cover members 14a' and 14b'. The elongated holes 122'Ha and 122'Hb are formed such that the sum of their lengths is greater than or equal to the difference between the specified displacement of anchor 11a and the specified displacement of anchor 11b. The anchor structure 1'' in Figure 13, having the above configuration, has the same function as the anchor structure 1'' of Embodiment 2. As is clear from this example, in applying the concept of the present invention as understood through the description of each embodiment, any structure having a similar function can be adopted, and such differences in specific structures do not constitute a difference in the concept of the present invention.

[0058] Embodiment 2 uses the example of suspending a suspended avalanche prevention fence, but the anchor structure is not limited to this. It can be used for various protective facilities such as protective fences and preventative fences against avalanches, rockfalls, and soil (landslides), triangular pyramidal frames installed for the purpose of avalanche prevention, pocket-type rock nets stretched to form pockets on slopes at risk of avalanches and rockfalls, and rope-hanging structures to hold down loose rocks along slopes. In addition, it can be used as a fixing means to support and hold any structure.

[0059] Figures 14 and 15 show an example in which the anchor structure according to the present invention is applied to a fixed protective fence (a protective fence having anchors directly connected to the support posts). Figure 14 shows a three-part anchor structure consisting of anchors 11a to 11c, with the anchor directly connected to the support post of the protective fence SF (the lower part of the support post underground) also being designated as anchor 11a of the anchor structure. Figure 14(a) is a side view conceptual diagram, and Figure 14(b) is a top view conceptual diagram.

[0060] In each embodiment, a configuration in which a tensile load is applied to the connecting member is used as an example, but the present invention is not limited to this, and a configuration in which a compressive load is applied to the connecting member is also possible. Figure 15(a) shows an example where the protective fence SF is positioned on the upper, sloping side of the anchor structure. In this case, each connecting member 12' will be subjected to a compressive load. Although there is a difference between tension and compression, the basic concept is the same as that described in the above embodiment. The anchors should be connected in the order in which the load is applied, from anchors with large specified displacement amounts to anchors with small specified displacement amounts, and elongated holes 1221H with the same length as the difference in specified displacement amounts between adjacent anchors should be provided (to absorb the displacement difference, which is the difference in specified displacement amounts between adjacent anchors). As shown in Figure 15(b), a configuration that utilizes both tension and compression may also be used. Furthermore, when compressive loads are applied, the connecting members must have the necessary rigidity to withstand the load, and members that would bend or flex generally cannot be used.

[0061] In each embodiment, an example is given in which multiple anchors are arranged in a straight line. However, "connecting in series" in the present invention is not limited to being in a straight line. Depending on the conditions of the construction site, they may be arranged in a zigzag pattern, for example. Furthermore, while it is desirable that each anchor be connected in series along the direction in which the load is applied, the direction in which the load is applied and the direction in which the anchors are aligned may differ.

[0062] <Embodiment 3> Figure 16 is a schematic side view showing a rockfall protection fence according to Embodiment 3 of the present invention. Figure 17(a) is a schematic plan view showing an anchor structure portion of a part of the rockfall protection fence according to Embodiment 3. The rockfall protection fence 2 of this embodiment comprises a plurality of support posts 21, a wire mesh 22 as a receiving member provided between the support posts 21, and a support post connecting member 25 that connects one of the anchors (in this case, anchor 11b) that constitute the anchor structure described in the above embodiment to the support post 21. In this embodiment, the rockfall protection fence 2 is installed on a slope, and the anchor 11b, located above the slope relative to the support post 21, is connected to the support post 21 by a support post connecting member 25. Furthermore, in this embodiment, the anchor 11b is driven perpendicular to the slope, and the support column connecting member 25 is positioned in a straight line with the anchor 11b. Regarding the basic structure of the rockfall protection fence, such as the support posts and receiving members, they can be the same as those of conventional, arbitrary rockfall protection fences, so a detailed explanation is omitted here.

[0063] The rockfall protection fence 2 of this embodiment has a structure in which the prevention or protection facility is supported by the anchor structure described in each of the above embodiments, and by further providing a support column connecting member 25, it enables the use of anchors more efficiently.

[0064] Figure 18 shows a conceptual diagram illustrating the load-bearing capacity of the anchor structure in the protective fence SF described in Figure 14. As can be understood from the descriptions of each embodiment above, for example, by using an anchor structure in which three anchors 11a to 11c having a yield strength of 100 kJ are connected in series, a protective fence SF capable of withstanding 300 kJ of energy can be obtained. Connecting the anchors in series provides the excellent effect of being able to flexibly change the configuration of the anchors. In addition, the rockfall protection fence 2 of this embodiment is designed so that the support column 21 and the anchor 11b are fastened together by the support column connecting member 25, thereby effectively utilizing the pull-out resistance of the anchor 11b. In other words, as shown in Figure 16, the load-bearing capacity of anchor 11b includes not only the load-bearing capacity against loads perpendicular to the longitudinal direction (axial direction) of the anchor, but also the load-bearing capacity (pull-out resistance) against loads applied along the longitudinal direction (axial direction) of the anchor (by fastening the support column 21 and anchor 11b with the support column connecting member 25). As conceptually shown in Figure 16, a rockfall protection fence 2 capable of withstanding 300 KJ of energy can be obtained by combining the perpendicular bearing capacity of anchor 11a (100 KJ), the perpendicular bearing capacity of anchor 11b (100 KJ), and the pull-out resistance of anchor 11b (100 KJ). Since the anchor 11b connected by the support column connecting member 25 is subjected to pull-out forces, it is preferable to use an anchor with high resistance to pull-out. For example, it is advisable to use various types of anchors that take pull-out resistance into consideration, such as the anchors described in Japanese Patent Publication No. 5542529 and Japanese Patent Publication No. 5597590.

[0065] As described above, according to the rockfall protection fence 2 of this embodiment, by fastening the support column 21 and the anchor 11b with the support column connecting member 25, the load is distributed in the direction of the support column connecting member 25, and the pull-out resistance of the anchor 11b can also be effectively utilized. Therefore, it is possible to reduce the horizontal load on the anchors, resulting in the excellent effect of reducing the number of anchors or using anchors with smaller cross-sections. It is also possible to reduce the cross-section of the support column itself, which is another excellent effect. As a result, the options for support columns and anchors that make up preventive or protective facilities increase (the number of combinations of each increases, allowing for a more flexible configuration), thus increasing the degree of design freedom.

[0066] In Figure 16, an example is shown in which a separate support column 21 and anchor 11a are connected vertically; however, the support column may be integrated with the anchor. When the support column is integrated with the anchor, for example, when an H-shaped steel beam is driven into the ground, the above-ground portion becomes the support column and the portion driven into the ground becomes the pile (anchor), the portion driven into the ground functions as one of the anchors constituting the anchor structure described in the above embodiment. That is, the anchor structure is constructed by connecting the member driven as an integrated support column and anchor with the anchor 11b using the connecting member 12.

[0067] Multiple anchors may be connected to each support column (anchor 11a). Figure 17(b) shows an example of this, where two anchors 11b are connected to each support column 21 (anchor 11a) by connecting members 12'. Of course, as explained in the embodiments described above, the number of anchors may also be increased or decreased in the series direction.

[0068] In this embodiment, the anchor 11b is provided perpendicular to the slope, and the support connecting member 25 is arranged in a straight line with respect to the anchor 11b as an example, but the present invention is not limited to this. For example, as illustrated in Figure 19, the anchor 11b may be driven in vertically, or the anchor 11b and the support column connecting member 25 may not be in a straight line. However, as described in this embodiment, if the anchor 11b is perpendicular to the slope and the anchor 11b and the support column connecting member 25 are in a straight line, the pull-out resistance of the anchor 11b can be utilized more effectively. Furthermore, in this embodiment, an anchor 11b located above the slope relative to the support column 21 is shown as an example, connected to the support column 21 by a support column connecting member 25. However, as shown in Figure 15(b), anchors may be placed on both sides of the prevention or protection facility, and the support column may be connected to the anchors by support column connecting members on both sides. In this case, the support column connecting member at the bottom of the slope will be subjected to a compressive load, and therefore needs to have the necessary rigidity against the compressive load. Furthermore, in preventative or protective facilities installed on surfaces other than slopes, anchor structures may be used for support, and the support columns and anchors may be connected by support column connecting members.

[0069] Any member having the necessary strength to withstand the expected tension can be used as the support column connecting member. Figure 20 shows an example of a support column connecting member. Figure 20(a) shows an example in which the support column connecting member 25 is made of steel material such as a flat bar. Mounting parts for attaching the support column connecting member 25, which is made of steel material, are formed at the top of the support column 21 and the anchor 11b, and they are connected to each other by the support column connecting member 25. Figure 20(b) shows an example in which the support column connecting member 25 is formed from a rope or other cable. Attachment parts for attaching the support column connecting member 25, which is made of a cable, are formed at the top of the support column 21 and the anchor 11b, and they are connected to each other by the support column connecting member 25. Figure 20(c) shows an example in which a length adjustment mechanism (or tension adjustment mechanism) 151 is provided on the support column connecting member 25. An example of the length adjustment mechanism (or tension adjustment mechanism) 151 is a turnbuckle or the like. In this example, the mounting portion of the support column connecting member 25 is provided as an attachment member 23 fixed (welded, etc.) to the support column 21 and an attachment member 24 (which may be a cover member) fixed (welded, etc.) to the head of the anchor 11b, with both ends of the support column connecting member 25 bolted to each of them. However, the present invention is not limited to this, and any mounting method that can be used to attach each of them can be used. It is preferable to attach the support column connecting member to the support column or anchor so that it can pivot, but it may also be attached so that it cannot pivot.

[0070] The mounting position of the support post connecting member to the support post is preferably within a range between the top end of the support post and half the height of the support post, such as a position that is 2 / 3H of the fence height H, as shown in Figure 19.

[0071] In this embodiment, a rockfall protection fence is used as an example of a preventative or protective facility, but the present invention is not limited to this, and the above concept can be applied to various types of preventative or protective facilities. Also, in this embodiment, wire mesh (face material) is used as an example of a receiving member, but various types of materials such as face materials, ropes, and beam members can be used as receiving members, depending on the purpose of each preventative or protective facility. [Explanation of Symbols]

[0072] 1... Anchor structure 11a, 11b... Anchors 12...Connecting members 121...Turnbuckle (length adjustment mechanism) 122...Displacement difference absorption structure 123a, 123b... Nut (reference part)

Claims

1. An anchor that is driven into the ground and generates load-bearing capacity while displacing in the direction of the load when subjected to a load, comprising a first anchor connected to the object to be supported, An anchor that is driven into the ground and generates load-bearing capacity while displacing in the direction of the load when subjected to a load, and a second anchor that is connected to the object to be supported via the first anchor, A connecting member for connecting the first anchor and the second anchor in series, the connecting member comprising a length adjustment mechanism for shortening the length of the connecting member, Equipped with, The length of the length adjustment mechanism for the connecting member has been shortened to eliminate any looseness between the members. An anchor structure in which there is no gap between the anchor and the hole drilled in the ground for installing the anchor at the point on the front side in the direction of the load from the supported object.

2. The anchor structure according to claim 1, wherein when the maximum load-bearing capacity of the anchor structure is generated, the displacement amounts of the first anchor and the second anchor are equal to the specified displacement amounts of each anchor.

3. Anchors of different specifications are connected in series. The anchor structure according to claim 1 or 2, wherein the load is applied first to the anchor with the largest specified displacement among the multiple anchors connected in series.

4. The anchor structure according to claim 3, wherein the plurality of anchors connected in series are connected in the order in which the load is applied, from the anchor with the largest specified displacement to the anchor with the smallest displacement.

5. The anchor structure according to any one of claims 1 to 3, wherein the load is applied first to the anchor with the largest diameter among the multiple anchors connected in series.

6. The anchor structure according to claim 5, wherein the plurality of anchors connected in series are connected in order of load application, from the largest diameter anchor to the smallest diameter anchor.

7. The anchor structure according to any one of claims 1 to 6, wherein the connecting member is equipped with a displacement difference absorbing structure that absorbs the difference in displacement between adjacent anchors, which is the difference in the specified amount of displacement.

8. The anchor structure according to claim 7, wherein the connecting member has play equal to the displacement difference due to the displacement difference absorption structure.

9. The anchor structure according to claim 7 or 8, wherein the connecting member comprises a reference portion for measuring the length adjustment amount of the length adjustment mechanism.

10. An anchor structure according to any one of claims 1 to 9, Multiple support posts, A receiving member provided between the aforementioned support columns, A support column connecting member that connects one of the plurality of anchors to the support column, A preventive or protective facility equipped with such facilities.

11. The prevention or protection facility according to claim 10, wherein the prevention or protection facility is installed on a sloping ground, and the support column is connected to any of the plurality of anchors located on the slope above the support column by the support column connecting member.

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