JP3733262B2 - Method and apparatus for static loading test of mesh body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is installed on a slope adjacent to a road, a railway, or a house, and captures a falling rock, debris flow, or avalanche generated on the slope, and falls on the road, a railway, or a house. The present invention relates to a net static loading test method for grasping the energy absorption characteristics of a net used to prevent this.
[0002]
[Prior art]
Conventionally, as this type of mesh body, as shown in FIGS. 7 and 8, a strand 1a made of mild steel having a wire diameter of 2.6 mm to 4.0 mm is bent in a saw blade shape, and the strand 1a There is known a net body 1 formed by weaving a plurality of the above-mentioned knives by inscribed their vertices at each pitch.
And this protection net | network 1 is, for example, standing up the support | pillar 2 which consists of I-shaped steel or H-shaped steel, as shown in FIG. The wire ropes 3 are inserted, and the ends of the wire ropes 3 and the ends of the strands 1a are fixed to the columns 2 so as to cover a predetermined area between the columns 2. And is used as a protective fence.
Further, as shown in FIG. 9, there is also known a mesh body 4 in which strands 4a are formed in a spiral shape, and a plurality of strands 4a are knitted so as to be inscribed at each pitch. Similar to the body 1, it is used as a protective fence by being fixed between the support columns 2 via a wire rope 3.
[0003]
And the absorption energy in such a net | network 1 (4) gives the evaluation value to the deformation | transformation form classification when a falling rock collides with a guard fence, and the form accompanying it, From the correlation figure with the kinetic energy of a falling rock It is determined by estimating the kinetic energy that breaks the net.
[0004]
[Problems to be solved by the invention]
However, in the calculation of the absorbed energy of the mesh body 1 (4) by the above-described method, since the estimation is based on the correlation diagram with the kinetic energy of falling rocks, the absorbed energy of the mesh body is quantitatively grasped. It has not reached.
[0005]
The present invention has been made in view of the above-described conventional problems, and a static loading test method for a net body capable of quantitatively grasping the absorbed energy of the net body used in the protective net as much as possible. An object is to provide an apparatus.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, in order to achieve the above-mentioned object, the net body static loading test method is provided by horizontally installing a net body used as a protective net on a rectangular frame. The mesh body is fixed on both sides of the gantry in one direction and is not fixed on both sides of the gantry in a direction perpendicular to the mesh body, and the mesh body is disposed below the center of the net in the surface direction. A load body to which a load is applied is brought into contact, and the load body is lifted by a jack to deform the net body, thereby measuring the load applied to the net body and the vertical displacement of the net body. The load-displacement characteristic of the mesh body is obtained by
In the method for static loading test of a mesh body according to claim 2 of the present invention, the aforementioned load body according to claim 1 is formed in a spherical shell shape so as to protrude toward the mesh body. It is characterized by.
According to a third aspect of the present invention, there is provided a method for static loading test of a net body, wherein when the jack according to the first or second aspect is operated up to the vicinity of an allowable stroke, the load body is set to a raised position. After the holding, the jack is contracted and the supporting position of the jack is raised.
According to a fourth aspect of the present invention, there is provided a static loading test apparatus for a net body, in which a net body used as a protective net is placed , and a frame that is assembled in a rectangular shape, and both sides in one direction of the frame. A fixing mechanism that is provided only on the upper surface and fixes the mesh body on both sides in one direction of the gantry, a loading body that is brought into contact with the lower surface of the central portion of the mesh body, and a substantially central portion of the gantry It is provided and is comprised by the jack which raises the load body mentioned above and applies a load to the said net | network body, It is characterized by the above-mentioned.
Furthermore, the static load test apparatus for a net body according to claim 5 of the present invention is configured such that when the load applied by the jack to the load body is removed from the load body according to claim 4, A hanging mechanism for holding the load body in the raised position is provided.
[0007]
According to the method for static loading test of a mesh body according to any one of claims 1 to 3, a static load is applied to the mesh body by gradually raising the loading body with a jack. By gradually increasing the static load, measuring the load at that time and the amount of displacement of the mesh body, and observing the correlation between them, the absorbed energy of the mesh body can be quantitatively determined even though it is a static load. I can grasp it.
And like invention of Claim 2, it can load in the state close | similar to the idealized rock fall model by forming a loading body in spherical shell shape.
Furthermore, as in the invention described in claim 3, when the jack is operated to the vicinity of the allowable stroke, the jack is contracted while the loaded body is held in the raised position, and the support position of the jack is further raised. Thus, even when a displacement exceeding the allowable stroke of the jack occurs in the net body, the measurement can be performed.
And according to invention of Claim 4 or Claim 5, the static loading test method of Claim 1 thru | or Claim 3 mentioned above can be implemented favorably.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail.
First, a structural example of a net static loading test apparatus suitably used in the present embodiment will be described with reference to FIGS.
[0009]
In these drawings, a static load test apparatus according to the present embodiment indicated by reference numeral 10 is provided with a gantry 11 on which a mesh body 1 (4) is placed, and upper surfaces of both sides of the gantry 11. (4) The fixing mechanism 12 for fixing both side portions, the loading body 13 brought into contact with the lower surface of the central portion of the mesh body 1 (4), and the loading body described above, provided at a substantially central portion of the gantry 11 And a jack 14 that applies a load to the net body 1 (4) by raising 13.
[0010]
Next, these details will be described. The gantry 11 is constructed by assembling a plurality of H-shaped steels 11a into a rectangular shape and stacking them in the vertical direction. A beam 11b made of H-shaped steel for fixing is attached.
Here, in this embodiment, since the reaction force of the jack 14 is supported by the gantry 11, the tensile force in the axial direction is received, so that a shearing force is prevented from acting on the bolts connecting the H-shaped steels 11 a. Therefore, as described above, each H-shaped steel 11a is stacked in the vertical direction, and each H-shaped steel 11a is fastened with a bolt so that only a tensile force acts on the bolt.
[0011]
As described in detail in FIG. 3, the aforementioned packing body 13 is formed by forming a spherical body having a diameter L into a spherical shell having a height L / 4 left from its apex.
A ring-shaped bottom plate 15 is integrally fixed to the inner periphery of the opening by welding, and the reinforcing plate 16 attached to the bottom plate 15 so as to pass through the center of the bottom plate 15 and the load body 13 described above. A plurality of reinforcing ribs 17 that are arranged from the vicinity of the opening toward the top of the spherical shell and that are in contact with the inner surface of the load body 13 over the entire length, the joint portions of the reinforcing plates 16 and the load body 13 described above. And a clevis 19 that is fixed to the core bar 18 through the apex of the load 13 and is integrally fixed.
Further, at the portion where the reinforcing plates 16 are connected to each other and located on the outer side of the load body 13, a recess 20 is formed in which the piston of the jack 14 is fitted and positioned.
[0012]
The lower end of the cylinder portion of the jack 14 is fixed to the beam 11b by a bolt or the like via the auxiliary piece 21 shown in FIG. 1, and the piston tip portion is positioned above the jack 14. The load body 13 is adapted to be fitted into the recess 20.
Further, in the present embodiment, as shown in FIG. 1, a displacement gauge 22 is attached to the auxiliary piece 21, and a wire W fixed in the vicinity of the piston tip of the jack 14 is connected to the piston. The displacement amount of the beam 11b, that is, the extension amount of the jack 14 is measured.
[0013]
Further, as shown in FIG. 4, the jack 14 has a hydraulic valve 23 that switches a supply mode of hydraulic oil via a hydraulic circuit, and a hydraulic pump that supplies the hydraulic oil to the jack 14 via the hydraulic valve 23. 24 and a pressure gauge 25 for detecting the pressure of hydraulic oil supplied from the hydraulic pump 24 are connected in series.
[0014]
The displacement gauge 22 and the pressure gauge 25 include information on the displacement of the piston output from the displacement gauge 22, that is, information on the displacement of the mesh body 1 (4), and the hydraulic oil output from the pressure gauge 25. A data logger 26 that generates a load-displacement curve by inputting the pressure information, that is, the load information is connected.
[0015]
As shown in FIG. 2, the fixing mechanism 12 includes a fixing plate 27 inserted inside the strands 1a (4a) on both sides of the mesh body 1 (4), and the fixing mechanism 27 as shown in FIG. The plate 27 is constituted by bolts 28 for fixing the flange 27 of the H-shaped steel 11 a constituting the mount 11.
A number of the bolts 28 are provided at predetermined intervals in the length direction of the H-shaped steel 11a, and each bolt 28 is provided vertically through the flange of the H-shaped steel 11a. The fixing plate 27 is clamped and fixed by a pair of nuts 30 screwed to the bolts 28 and fixed to the flange by nuts 29 screwed from above the flanges.
[0016]
Further, in the present embodiment, a suspension mechanism 31 is provided on the load body 13 to hold the load body 13 in the raised position when the load applied by the jack 14 to the load body 13 is removed. It has been.
The suspension mechanism 31 includes a crane (not shown) and a tension meter 32 such as a load cell attached to the crane and connected to the clevis 19 of the load 13 described above.
[0017]
Next, an embodiment of the static loading test method of the present invention will be described together with the operation of the static loading test apparatus 10 of the present embodiment configured as described above.
First, both sides of the mesh body 1 (4) are fixed to the gantry 11 via the fixing mechanism 12, and the loading body 13 is mounted on the suspension mechanism 31, and the loading body 13 is raised by the suspension mechanism 31. The lower part of the center of the net 1 (4) is brought into contact.
Next, the jack 14 is operated, and the tip end portion of the piston is fitted into the recess 20 formed in the load body 13 and stopped.
[0018]
In this state, the pressure of the hydraulic oil supplied to the jack 14 is detected by the pressure gauge 25, and the piston position is detected based on the output from the displacement gauge 22.
Since this state is an unloaded state with respect to the net body 1 (4), the pressure gauge 25 and the displacement gauge 22 are reset to be set to an initial state.
As a result, the hydraulic oil is supplied to the jack 14 and a load is applied to the center of the net 1 (4) to deform the net 1 (4).
This deformation is performed by intermittent driving in which the extension amount of the jack 14 is stopped when it reaches a predetermined value, and the jack 14 is operated again in the extension direction after the stop time has elapsed for a predetermined time.
For example, when the extension amount of the jack 14 reaches 50 mm, the supply of the hydraulic oil to the jack 14 is stopped, and then the operation of the jack 14 is started after the operation of the jack 14 is stopped for 3 minutes.
As described above, the operation of the jack 14 is intermittently performed after the operation of the jack 14 is stopped, and the deformation of the net body 1 (4) is continuously performed, and accordingly, the net body 1 (4) is added. This is because the load gradually decreases, but a static state for converging the decreased load is formed.
[0019]
Then, during the period from the stop of the jack 14 to the next operation, the amount of displacement of the mesh body 1 (4) is measured every predetermined amount of displacement, and the operating oil of the jack 14 is measured at predetermined time intervals. The pressure, that is, the load is measured in a plurality of stages.
[0020]
Here, when the maximum deformation amount of the mesh body 1 (4) exceeds the maximum stroke of the jack 14, the test is continued as follows.
That is, when the jack 14 is extended to a predetermined stroke, the loading body 13 is fixed by the suspension mechanism 31, and then the jack 14 is contracted, and the jack 14 and the auxiliary piece 21 have a predetermined thickness. After the auxiliary piece was inserted and fixed, the piston of the jack 14 was again fitted into the recess 20 of the loading body 13, thereby continuing the operation of the jack 14 again after restraining the movement of the loading body 13. The test becomes possible.
Then, by making the thickness of the interposed auxiliary piece coincide with the predetermined stroke of the jack 14 described above, the subsequent displacement can be easily detected.
Here, when the jack 14 is removed, the load acting on the mesh body 1 (4) acts on the suspension mechanism 31 as it is. By detecting this load with the tensiometer 31, It is possible to prevent an overload on the suspension mechanism 31.
[0021]
The relationship between the load and the displacement with respect to the net 1 (4) thus measured can be calculated by the data logger 26 to obtain the load-displacement characteristic.
Here, the result of having performed such a static loading test with respect to the net 1 shown in FIGS. 7 and 8 and the net 4 shown in FIG. 9 is shown in FIG.
In this figure, a curve A is a load-displacement curve for the net body 1, and a curve B is a load-displacement curve for the net body 4. From this result, although the load increases linearly at the initial stage of the displacement amount, it can be clearly understood that the load suddenly rises at the end stage and the net body 1 (4) is broken.
Therefore, according to this embodiment, although it is a static load, the deformation | transformation characteristic until it leads to destruction of the net body 1 (4) is calculated | required quantitatively.
[0022]
The various shapes, dimensions, and the like of the constituent members shown in the embodiments are merely examples, and can be variously changed based on design requirements and the like.
[0023]
【The invention's effect】
As described above, according to the method for static loading test of a mesh body according to any one of claims 1 to 3 of the present invention, the load body is gradually raised by a jack so that The static load is gradually increased while applying a static load, the load at that time and the displacement of the mesh body are measured, and the correlation between these is observed. The absorbed energy can be grasped quantitatively. And like invention of Claim 2, it can load in the state close | similar to the idealized rock fall model by forming a loading body in spherical shell shape.
Further, as in the invention described in claim 3, when the jack is operated to the vicinity of the permissible stroke, the jack is contracted while the loaded body is held in the raised position, and the support position of the jack is further raised. Thus, even when a displacement exceeding the allowable stroke of the jack occurs in the net body, the measurement can be performed.
And according to invention of Claim 4 or Claim 5, the static loading test method of Claim 1 thru | or Claim 3 mentioned above can be implemented favorably.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of the present invention.
FIG. 2 is a plan view showing an embodiment of the present invention.
FIGS. 3A and 3B show a side view and a bottom view of a loaded body according to an embodiment of the present invention. FIGS.
FIG. 4 is a schematic view showing a jack and its driving member according to an embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a main part showing a fixing mechanism for fixing a net body according to an embodiment of the present invention.
FIG. 6 is a load-displacement curve diagram of a net obtained by an embodiment of the present invention.
FIG. 7 is a front view showing a structural example of a net.
8 is a longitudinal sectional view of FIG.
FIG. 9 is a longitudinal sectional view showing another structural example of the net.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Net body 1a Strand 2 Strut 3 Wire rope 4 Net body 4a Strand 10 Static loading test apparatus 11 Mounting frame 11a H-shaped steel 11b Beam 12 Fixing mechanism 13 Loading body 14 Jack 15 Bottom plate 16 Reinforcement plate 17 Reinforcement rib 18 Core rod 19 Clevis 20 Recess 21 Auxiliary piece 22 Displacement gauge 23 Hydraulic valve 24 Hydraulic pump 25 Pressure gauge 26 Data logger 27 Fixing plate (fixing mechanism)
28 bolts (fixing mechanism)
29 Nut (Fixing mechanism)
30 Nut (fixing mechanism)
31 Suspension mechanism 32 Tensile meter W Wire

Claims (5)

A net used as a protective net is installed horizontally on a rectangular frame, and the net is fixed on both sides in one direction of the frame, and both sides of the frame in a direction perpendicular thereto. A load body that applies a load to the net body is brought into contact with a lower portion of the center portion in the surface direction of the net body without being fixed on the upper side, and the net body is deformed by raising the load body with a jack. And measuring the load applied to the mesh body and the vertical displacement of the mesh body to thereby determine the load-displacement characteristics of the mesh body. 2. The static loading test method for a mesh body according to claim 1, wherein the load body is formed in a spherical shell shape so as to protrude toward the mesh body. 2. When the jack is operated to the vicinity of an allowable stroke, the jack is contracted and the supporting position of the jack is raised after holding the load body in the raised position. 3. A static loading test method for a mesh body according to 2. Placed mesh member is used as a guard net, a frame that is assembled in a rectangular shape, provided only on both sides the upper surface of the one-way this frame, the net assembly on both sides of the one-way of the said frame A fixing mechanism for fixing, a loading body that is brought into contact with the lower surface of the central portion of the net body, and a jack that is provided at a substantially central portion of the gantry and raises the load body to apply a load to the net body. A static loading test apparatus for a mesh body, characterized in that The suspension according to claim 4, further comprising: a hanging mechanism that holds the load in a raised position when the load applied by the jack to the load is removed from the load. Static loading test equipment for nets.

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