JP6474998B2 - Fall control method and pier - Google Patents

Description

  The present invention relates to a fall prevention method that makes it difficult for an existing pier provided directly on the ground to fall, and a pier that is difficult to fall.

Conventionally, an existing pier whose foundation is a “direct foundation” or an existing pier that is a “pile foundation having a structure in which the pile and the foundation are not connected” is known. Since such existing piers are directly provided on the ground (including ground reinforced with wooden piles, etc.), they may fall over due to an earthquake or the like.
As a fall-suppressing construction method that makes it difficult for such existing piers to fall, for example, a construction method in which the ground and the pier are integrated with a ground anchor (for example, see Patent Document 1), or a construction method that increases the contact area between the ground and the pier. And so on.

JP 9-209373 A

However, in the case of the construction method in which the ground and the pier are integrated with the ground anchor, the anchor is large and the ground anchor fixing portion of the pier needs to be reinforced, which increases the cost.
In the case of a construction method that increases the contact area between the ground and the pier, when the pier is installed in a river or sea, it must be shielded to install a member that increases the contact area. For this reason, a large-scale facility is required, resulting in problems such as increased costs and a longer construction period. In addition, water leakage may occur and it may not be possible to construct safely.

The present invention has been made in view of the circumstances as described above, and is a toppling-suppressing construction method that makes it difficult for the existing bridge pier directly provided on the ground to fall, and can be inexpensively and safely constructed, and An object of the present invention is to provide a fall prevention method capable of shortening the work period.
Moreover, the other objective of this invention is to provide the bridge pier which cannot fall easily.

In order to solve the above problems, the fall prevention method of the present invention is
A fall prevention method that makes it difficult for the existing piers directly on the ground to fall,
When the ground shake occurs, the upper part above the cutting position and the lower part below the cutting position slide relatively, and the positional relationship between the upper part and the lower part is shifted. If produced, the so that the cut surface to produce a restoring force to the positional relationship is formed, and is configured to cut the existing piers.

Therefore, since the existing pier is only cut, inexpensive and safe construction is possible, and the construction period can be shortened.
In addition, even if the upper part and the lower part slide relative to each other and the positional relationship between the upper part and the lower part is displaced, a restoring force is generated and the original positional relationship is restored naturally. Can do.

Preferably,
A slide member may be installed between the upper part and the lower part.

  By comprising in this way, since an upper part and a lower part become easy to slide relatively, it becomes possible to suppress a fall effectively.

The pier of the present invention is
A pier directly on the ground,
It is separated up and down,
Have a sliding structure for the separation boundary,
When said deviation of the positional relationship between the upper and lower slides in separation boundary occurs it is configured to so that rise to restoring force of the positional relationship.

Therefore, when an earthquake occurs, it is possible to control a sliding mechanism rather than a tilting mechanism, and thus it is possible to provide a bridge pier that does not easily fall over.
In addition, even if the upper and lower positional relationship is shifted by sliding at the separation boundary, a restoring force is generated and the original positional relationship can be restored naturally.

According to the present invention, it is possible to provide a fall-suppressing construction method capable of inexpensive and safe construction and shortening the construction period.
In addition, it is possible to provide a pier that does not easily fall over.

It is a figure which shows an example of a structure of the existing pier. It is a figure which shows an example of the structure of the example of the fall control method of 1st Embodiment, and the pier (fall-resistant bridge pier) of 1st Embodiment. It is a figure which shows the example of a slide structure. It is a figure which shows an example of the procedure of the fall suppression construction method of 1st Embodiment. It is a figure which shows an example of the structure of the pier (fall-resistant bridge pier) of 2nd Embodiment, an example of the fall control method of 2nd Embodiment. It is a figure which shows another example of the fall prevention construction method of 2nd Embodiment, and another example of the structure of the bridge pier (fall-resistant bridge pier) of 2nd Embodiment.

  With reference to the drawings, embodiments of the overturning suppression method and the pier according to the present invention will be described. The embodiments described below are given various technically preferable limitations for carrying out the present invention, but the scope of the present invention is not limited to the following embodiments and illustrated examples.

[First Embodiment]
First, the existing pier 10 will be described.
FIG. 1 is a diagram illustrating an example of the configuration of an existing pier 10.
The existing pier 10 is a rail pier made of unreinforced concrete. As shown in FIG. 1, as shown in FIG. 1, a floor slab 1, which has a quadrangular pillar shape and can be laid with a track, is installed via a bridge girder 2. .

  The existing pier 10 is directly provided on the ground (including ground reinforced by wooden piles and the like). That is, the foundation of the existing pier 10 is a “direct foundation” or a “pile foundation having a configuration in which the pile and the foundation are not connected”. Therefore, the existing pier 10 may be tilted due to the inertial force of the earthquake and may fall down in some cases during an earthquake. Therefore, in the present embodiment, in order to change the existing pier 10 to the fall-resistant pier 20 that is harder to fall than the existing pier 10, for example, as shown in FIG. 2 and FIG. The existing pier 10 is cut so as to be orthogonal to the upper part 21 and the upper part 21 on the upper side from the cutting position and the lower part 22 on the lower side from the cutting position are configured to be relatively slidable. By configuring in this way, it becomes possible to make the sliding mechanism more dominant than the tilting mechanism when an earthquake occurs, so that it is difficult to fall.

  The overturn-resistant pier 20 is separated into an upper portion 21 and a lower portion 22 that can be relatively slid. If the frictional force between the upper part 21 and the lower part 22 is negligibly small, the inertial force of the earthquake acts on the lower part 22 installed on the ground, but the upper part 21 has an earthquake. Since neither the inertia force nor the force from the lower portion 22 acts, the upper portion 21 does not shake or tilt even if an earthquake occurs, and can maintain the state before the occurrence of the earthquake. The greater the inertial force of the earthquake, the greater the moment for tilting the lower portion 22 (the moment of force around the overturning fulcrum of the lower portion 22), so the lower portion 22 tends to tilt. On the other hand, a force in a direction to cancel the moment acts on the lower portion 22 from the upper portion 21. Therefore, if the moment to tilt the lower portion 22 is large enough to be canceled out by the force from the upper portion 21, the lower portion 22 does not tilt and rolls together with the ground, and the upper portion 21 Slide relative to. Therefore, depending on the magnitude of the moment to tilt the lower portion 22 and the magnitude of the force in the direction to cancel the moment to tilt the lower portion 22, it depends on the tilting mechanism when an earthquake occurs. The sliding mechanism becomes dominant.

The position at which the existing pier 10 is cut can be appropriately set according to the size of the existing pier 10, the shape of the installation location of the existing pier 10, the seismic performance required at the installation location of the existing pier 10, etc. From the viewpoint of reducing the moment for tilting the side portion 22 and increasing the force in the direction for canceling the moment for tilting the lower portion 22, the position at which the existing pier 10 is cut is determined by the existing pier 10 It is preferable that it is below the center of gravity position.
The moment to incline the structure is proportional to the distance between the center of gravity of the structure and the fall fulcrum. That is, when a force having the same magnitude as the inertial force of an earthquake acts on the center of gravity, the shorter the distance between the center of gravity and the falling fulcrum, the smaller the moment for tilting the structure. The lower the position of the center of gravity of the lower part 22 is, the shorter the distance between the center of gravity of the lower part 22 and the falling fulcrum is. Therefore, the position of the center of gravity of the lower part 22 is preferably lower.
Moreover, since the force of the direction which cancels the moment which makes the lower part 22 incline increases so that the weight of the upper part 21 is large, the one where the weight of the upper part 21 is large is preferable.

Further, it is preferable that the upper portion 21 and the lower portion 22 are slid relatively easily (the smaller the frictional force between the upper portion 21 and the lower portion 22), the more difficult it is to fall.
As the upper portion 21 and the lower portion 22 are relatively difficult to slide relative to each other, the upper portion 21 acts as an inertial force by the magnitude of the frictional force and swings or tilts in accordance with the movement of the lower portion 22. It becomes easy. Therefore, since it becomes difficult for the upper part 21 to maintain the state before the occurrence of the earthquake, the force in the direction to cancel the moment to tilt the lower part 22 is reduced. Furthermore, the moment that acts on the lower portion 22 as a reaction force by the magnitude of the inertial force received by the upper portion 21 increases the inclination of the lower portion 22 or the entire pier.
On the other hand, as the upper part 21 and the lower part 22 slide relatively easily, the state of the upper part 21 is not affected by the state of the lower part 22, and the upper part 21 can easily maintain the state before the occurrence of the earthquake. Therefore, the force in the direction to cancel the moment for tilting the lower portion 22 is increased, and it is more difficult to fall. Therefore, for example, as shown in FIG. 3A, the cut surface may be used as it is, but in order to make it easier to slide, lubricating oil is injected into the gap between the upper portion 21 and the lower portion 22. It is preferable to coat the cut surface with a lubricant or install a slide member between the upper portion 21 and the lower portion 22.

  The slide member is not particularly limited. For example, a free ball bearing 23 is used as shown in FIG. 3B, or a plate having a surface friction coefficient smaller than that of the cut surface as shown in FIG. 3C, for example. 24 can be used in an overlapping manner. As the plate 24, for example, a plate made of a known material such as a fluororesin, a plate subjected to a known surface treatment such as a fluorine coating treatment, or the like can be used.

That is, the sliding structure of the overturn-resistant pier 20 may be configured by mutually facing surfaces (cut surfaces) in the upper portion 21 and the lower portion 22 (see FIG. 3A), or on the upper side. The part 21 and the lower part 22 may be configured by mutually facing surfaces (cut surfaces) and a lubricant that coats these surfaces, or the upper part 21 and the lower part 22 may be mutually connected. Even if it is comprised by any one of the surfaces (cut surface) which opposes, and the slide member installed between the upper part 21 and the lower part 22 (refer FIG.3 (b)). Alternatively, it may be configured by a slide member installed between the upper part 21 and the lower part 22 (see FIG. 3C).
Which slide structure is adopted is appropriately set according to the state of the cut surface, the size of the existing pier 10, the shape of the installation location of the existing pier 10, the seismic performance required at the installation location of the existing pier 10, etc. Is possible.

Next, a description will be given of the procedure of the fall prevention method for making the existing pier 10 provided directly on the ground difficult to fall, that is, the fall prevention method for changing the existing pier 10 to the fall-resistant bridge pier 20. Below, the case where the free ball bearing 23 is provided as a slide member between the upper part 21 and the lower part 22 is demonstrated to an example.
FIG. 4 is a diagram illustrating an example of a procedure of the overturning suppression method when a free ball bearing 23 is provided as a slide member between the upper portion 21 and the lower portion 22.

First, as shown to Fig.4 (a), (b), the supporting member S which supports the part used as the upper part 21 is fixed to the existing pier 10 using a post-construction anchor etc. (illustration omitted). As long as the support member S is a member having the required support performance, there are no particular limitations on the material, structure, and the like, and known members can be used.
Subsequently, as shown in FIG.4 (b), the existing pier 10 is cut | disconnected using cutting machines, such as a wire saw. When the existing pier 10 is cut using a cutting machine, the cutting is about the thickness of the blade of the cutting machine (for example, the diameter of the wire when the cutting machine is a wire saw) between the upper part 21 and the lower part 22. For example, when a slide member thicker than the cutting width is installed between the upper portion 21 and the lower portion 22, the upper portion 21 and the lower portion 22 are made larger than the cutting width. Since there is a need to separate them at intervals, there are two cutting positions as shown in FIG. On the other hand, when the cut surface is used as it is (see FIG. 3A), when lubricating oil is injected into the gap between the upper portion 21 and the lower portion 22, or a slide member having a thickness equal to or less than the cutting width is installed. In such a case, it is not necessary to separate the upper portion 21 and the lower portion 22 from each other with a larger interval than the cutting width, and therefore only one cutting position is required.

Next, as shown in FIG. 4C, the formed body (in the case of this embodiment, unreinforced concrete) that forms the existing pier 10 is removed from between the upper part 21 and the lower part 22.
And as shown in FIG.4 (d), the free ball bearing 23 is installed between the upper part 21 and the lower part 22, and the support member S is removed. In this way, the existing pier 10 can be changed to the fall-resistant pier 20.
In the middle of cutting the existing pier 10, it is also possible to install a known support machine such as a flat jack in the gap generated by the cutting and remove the support machine after installing the slide member. Further, in the middle of cutting the existing pier 10, it is possible to install a free ball bearing 23, a plate 24, etc. in the gap generated by the cutting and use it as a slide member as it is. In these cases, the support member S may not be installed before the existing pier 10 is cut.

  According to the fall control method of the first embodiment described above, it is a fall control method that makes it difficult for the existing bridge pier 10 provided directly on the ground to fall, and when the ground shakes, the upper side from the cutting position is the upper side. The existing pier 10 is cut so that the portion 21 and the lower portion 22 below from the cutting position slide relative to each other.

Therefore, since only the existing pier 10 is cut, inexpensive and safe construction is possible, and the construction period can be shortened.
Specifically, since the existing pier 10 is only cut, reinforcement during construction is unnecessary or small-scale reinforcement is sufficient. Therefore, compared with the conventional fall prevention construction methods, such as the construction method which integrates a ground and a bridge pier with a ground anchor, cheap construction becomes possible.
Since the existing pier 10 is only cut, even if the existing pier 10 is installed in a river or the sea, the work can be performed on the water surface if the cutting position is on the water surface. Therefore, large-scale facilities for water shielding are not necessary, and it is not necessary to consider safety against water leakage, so compared with conventional methods for preventing overturning such as methods that increase the contact area between the ground and the pier. Therefore, inexpensive and safe construction is possible, and the construction period can be shortened.
Furthermore, it is a construction method that increases the contact area between the ground and the pier, and when the pier is a railway pier, in a narrow space near the track, the construction becomes complicated, and a place to install a member that increases the contact area is installed. Although problems, such as being unable to ensure, arise, since the existing pier 10 is only cut, construction that is not affected by the track (track) becomes possible.

  Moreover, according to the fall suppression construction method of 1st Embodiment, it can be comprised so that the existing pier 10 may be cut | disconnected so that the cut surface orthogonal to a perpendicular direction may be formed.

  By configuring in this way, the existing bridge pier 10 may be cut horizontally, and the cutting work is simple. Therefore, it is possible to carry out a cheaper and safer construction and further shorten the construction period.

  Further, according to the overturning suppression method of the first embodiment, a slide member (free ball bearing 23, plate 24 having a smaller surface friction coefficient than the cut surface) is provided between the upper portion 21 and the lower portion 22. It can be configured to be installed.

  By comprising in this way, since the upper part 21 and the lower part 22 become easy to slide relatively, it becomes possible to suppress a fall effectively.

  Moreover, according to the pier of 1st Embodiment, it is the pier (fall-resistant pier 20) directly provided in the ground, Comprising: It is isolate | separated up and down, and it is comprised so that it may have a slide structure in a separation boundary. .

  Therefore, since it is possible to control the sliding mechanism rather than the tilting mechanism when an earthquake occurs, it is possible to provide a bridge pier (fall-resistant bridge pier 20) that does not easily fall over.

[Second Embodiment]
In 1st Embodiment, in order to change the existing pier 10 into the fall-resistant pier 20 which is harder to fall than the said existing pier 10, the existing pier 10 is cut | disconnected and cut | disconnected so that a cut surface may orthogonally cross with respect to a perpendicular direction. Although the upper part 21 on the upper side from the position and the lower part 22 on the lower side from the cutting position are configured to be relatively slidable, in the second embodiment, the existing pier 10 is made to be more than the existing pier 10. In order to change to a toppling-resistant pier 30 that is not easily toppled, the existing pier 10 is cut so that the cut surface is an inclined surface that is inclined toward the central axis C of the existing pier 10, and the upper portion 31 on the upper side from the cutting position is cut. The lower part 32 on the lower side is configured to be relatively slidable from the cutting position. Even in such a configuration, it is possible to make the sliding mechanism more dominant than the tilting mechanism when an earthquake occurs, so that it is difficult to fall. Further, with this configuration, even if the upper portion 31 and the lower portion 32 slide relative to each other and the positional relationship between the upper portion 31 and the lower portion 32 is shifted, the restoring force due to gravity is reduced. It can occur and return to the original positional relationship.

  As a cut surface formed of an inclined surface inclined toward the central axis C of the existing pier 10, for example, as shown in FIG. 5A, a cut surface formed of two inclined surfaces inclined toward the central axis C, for example, FIG. As shown in FIG. 6 (a), there may be mentioned those composed of four inclined surfaces inclined toward the central axis C.

  The fall-resistant bridge pier 30 shown in FIG. 5A has a cut surface composed of two inclined surfaces inclined in the horizontal direction orthogonal to the extending direction of the bridge girder 2. Therefore, in the fall-resistant bridge pier 30, an earthquake occurs and the upper part 31 and the lower part 32 slide relative to each other, and the positional relationship between the upper part 31 and the lower part 32 extends the bridge girder 2. Even if it is shifted in the horizontal direction perpendicular to the direction, as shown in FIG. 5 (b), the restoring force that restores the positional relationship is generated by the gravity acting on the upper portion 31, so that the original positional relationship is naturally restored. You can go back.

In the example shown in FIG. 5A, the inclination direction of the inclined surface is the horizontal direction orthogonal to the extending direction of the bridge girder 2, but the present invention is not limited to this, and the inclination direction of the inclined surface is: For example, the extending direction of the bridge girder 2 may be used.
Moreover, it is also possible to configure to have a plurality of cut surfaces composed of two inclined surfaces inclined toward the central axis C. In this case, as shown in FIG. 5 (c), if the inclined direction of the inclined surface constituting one cut surface is different from the inclined direction of the inclined surface constituting the other cut surface, a plurality of directions are obtained. This is preferable because it can cope with the deviation. Here, in the overturn-resistant pier 30 shown in FIG. 5C, the portion sandwiched between the upper cut surface and the lower cut surface is the lower portion 32 when viewed from the upper cut surface, Since it is the upper portion 31 when viewed from the lower cut surface, the reference numerals “31, 32” are given in FIG.

  A tip-over resistant pier 30 shown in FIG. 6A is a cone composed of two inclined surfaces inclined in the horizontal direction perpendicular to the extending direction of the bridge girder 2 and two inclined surfaces inclined in the extending direction of the bridge girder 2. It has a cut surface. Therefore, in the fall-resistant bridge pier 30, even if the positional relationship between the upper portion 31 and the lower portion 32 is deviated, a restoring force due to gravity is generated regardless of the deviated direction, and naturally the original positional relationship. You can return to

In addition, the cut surface of the fall-resistant bridge pier 30 shown to Fig.6 (a) may be curved as shown, for example in FIG.6 (b).
Moreover, the cut surface of the overturn-resistant pier 30 shown in FIG. 5A may also be curved, for example, as shown in FIG. The same applies to the cut surface of the overturn-resistant pier 30 shown in FIG.
In addition, which shape is adopted as the shape of the cut surface is appropriately set according to the direction of ground shaking assumed at the installation location of the existing pier 10 or the seismic performance required at the installation location of the existing pier 10. Is possible.
Further, depending on the state of the cut surface, the size of the existing pier 10, the shape of the installation location of the existing pier 10, the seismic performance required at the installation location of the existing pier 10, etc., between the upper portion 31 and the lower portion 32. It is also possible to install a slide member on.

  According to the overturning suppression method of the second embodiment described above, the upper portion 31 and the lower portion 32 are relatively slid and the positional relationship between the upper portion 31 and the lower portion 32 is shifted. In such a case, the existing pier 10 can be cut so that a cutting surface that generates a restoring force to restore the positional relationship is formed.

With this configuration, even if the upper portion 31 and the lower portion 32 slide relative to each other and the positional relationship between the upper portion 31 and the lower portion 32 is shifted, a restoring force due to gravity is obtained. It can occur and return to the original positional relationship.
In the present embodiment, the overturn-resistant pier 30 has a cut surface formed of an inclined surface that is inclined downward toward the central axis C, but is not limited to this. For example, the central axis C You may have the cut surface which consists of an inclined surface which inclines upward toward.
Further, in the present embodiment, the overturn-resistant pier 30 has a cut surface composed of a plurality of inclined surfaces inclined toward the central axis C, but is not limited to this. You may have the cut surface which consists of several inclined surfaces which incline toward the line | wire in the position which shifted | deviated.
Further, in the present embodiment, one line is set, and the existing pier 10 is cut so that a cut surface composed of an inclined surface inclined toward the line is formed. However, the present invention is not limited to this. Alternatively, a plurality of lines may be set. That is, in the present embodiment, the existing pier 10 is cut into a substantially V shape when viewed from one side surface, but is not limited thereto, and may be cut into a substantially W shape, for example.

  Moreover, according to the pier of 2nd Embodiment, it is the pier (fall-resistant pier 30) directly provided in the ground, Comprising: It is isolate | separated up and down, and it is comprised so that it may have a slide structure in a separation boundary. .

  Therefore, as with the overturn-resistant pier 20 of the first embodiment, it is possible to control the sliding mechanism rather than the tilting mechanism when an earthquake occurs, so the pier that does not easily fall over (the overturn-resistant pier 30). Can be provided.

  In the above-described embodiment, the configuration and the like illustrated in the accompanying drawings are merely examples, and are not limited thereto, and can be appropriately changed within the scope of the effects of the present invention. . In addition, various modifications can be made without departing from the scope of the object of the present invention.

The existing pier 10 is not limited to non-reinforced concrete, and may be made of reinforced concrete, brick, stone, or the like.
Further, the existing pier 10 is not limited to a railway pier, and may be another pier.
Further, the shape of the existing pier 10 is not limited, and may be a polygonal column shape, a columnar shape, or a flared shape (such as a polygonal frustum or a truncated cone). Further, the side surface of the existing pier 10 may be uneven. The existing pier 10 may be erected in the vertical direction or may be erected obliquely with respect to the vertical direction.

10 Existing piers 20, 30 Fall-resistant piers (piers)
21, 31 Upper part 22, 32 Lower part 23 Free ball bearing (slide member)
24 Plate (sliding member) with a smaller coefficient of friction than the cut surface

Claims (3)

A fall prevention method that makes it difficult for the existing piers directly on the ground to fall,
When the ground shake occurs, the upper part above the cutting position and the lower part below the cutting position slide relatively, and the positional relationship between the upper part and the lower part is shifted. If produced, tipping suppression method, characterized in that the so that the cut surface to produce a restoring force to the positional relationship is formed, cutting the existing piers. The fall prevention method according to claim 1, wherein a slide member is installed between the upper part and the lower part. A pier directly on the ground,
It is separated up and down,
Have a sliding structure for the separation boundary,
When said shift slides separated boundaries above and below the positional relationship occurs, and wherein the Rukoto generate restoring force the positional relationship piers.

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