JP6474997B2 - Fall prevention method - Google Patents

Description

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

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,
Lowering the center of gravity position of the existing pier by removing a part of the formed body that forms the existing pier from at least the portion above the center of gravity of the existing pier ,
Before or after removal the formed body, the lower portion than the center of gravity of the existing piers has been configured to secure the weight.

Therefore, since the center of gravity of the existing pier is only lowered, inexpensive and safe construction is possible, and the construction period can be shortened.
Moreover, since only a part of the forming body that forms the existing pier is removed from at least the portion above the center of gravity of the existing pier, inexpensive and safe construction is possible, and the construction period can be shortened. .
Further, since the position of the center of gravity can be further lowered, it is possible to make it more difficult to fall.

Preferably,
As the weight, at least a part of the removed formed body can be used.

  By comprising in this way, since the removed formation body can be reused, cheaper construction becomes possible.

Preferably,
When there is a convex part on the side surface of the lower part of the center of gravity of the existing pier, or when the existing pier has a hem-extended shape, the annular member to which the weight is attached is connected to the center of gravity of the existing pier. The weight is fixed by moving from the upper part to the lower part so that the upper part has a play and is hooked to the lower part. It can be configured to do so.

  By comprising in this way, even if it is a case where the existing pier is installed in the river or the sea, the fixing work of the weight can be performed safely.

  According to the present invention, inexpensive and safe construction is possible, and the construction period can be shortened.

It is a figure which shows an example of a structure of the existing pier. It is a figure for demonstrating the fall limit. It is a figure explaining an example of the fall prevention construction method of a 1st embodiment. It is a figure which shows an example of the method of reinforcing the part which removed the formation body. It is a figure which shows an example of the procedure of the fall suppression construction method of 1st Embodiment. It is a figure explaining an example of the fall suppression construction method of 2nd Embodiment. It is a figure explaining an example of the fall control method of a 3rd embodiment.

  With reference to the drawings, an embodiment of the overturning suppression method 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, the existing pier 10 is lightened by reducing the weight above the center of gravity of the existing pier 10. The center of gravity position of 10 is lowered. In the following description, a horizontal plane including the center of gravity of the existing pier 10 is defined as a boundary surface, a portion above the boundary surface is referred to as “upper A”, and a portion below the boundary surface is referred to as “lower portion B”. .

Here, it is known that even if the entire structure is reduced in weight or weight, the overturning performance of the structure does not change, but if the position of the center of gravity of the structure is changed, the overturning performance of the structure changes. ing.
Even if the structure is inclined, the structure does not fall unless the center of gravity G of the structure exceeds the vertical line L passing through the rotation center (falling fulcrum) O of the structure, but the center of gravity G exceeds the vertical line L. And the structure falls. That is, as shown in the right diagrams of FIGS. 2A and 2B, the fall limit is when the center of gravity G is located on the vertical line L passing through the rotation center (falling fulcrum) O. The greater the fall limit angle θ (the tilt angle of the structure at the time when the fall limit is reached), the greater the tilt angle required before the fall, and thus the more difficult to fall. The fall limit angle θ does not change even if the entire structure is reduced in weight or weight, but changes when the position of the center of gravity of the structure is changed. Specifically, the fall limit angle θ increases when the position of the center of gravity G is lowered, and the fall limit angle θ decreases when the position of the center of gravity G is increased. For example, the structure shown in FIG. 2B is provided with a through hole H at the top, and therefore has a center of gravity as compared with the structure shown in FIG. 2A (the structure before the through hole H is provided). Since the position of G is low and the fall limit angle θ is large, it is difficult to fall.

  In the case of this embodiment, since the existing pier 10 has a quadrangular prism shape and is entirely uniform, the center of gravity of the existing pier 10 is located at the center of the existing pier 10 in the height direction. Therefore, if the position of the center of gravity is changed to be lower than the center in the height direction, the fall limit angle θ becomes large and it is difficult to fall.

In the present embodiment, the center of gravity of the existing pier 10 is determined by removing a part of the formed body (unreinforced concrete in this embodiment) that forms the existing pier 10 from the upper part A of the existing pier 10. Lower.
FIG. 3 is a diagram illustrating an example of the overturning suppression method according to the first embodiment.
For example, as shown in FIG. 3A, as a method of removing a part of the forming body that forms the existing pier 10 from the upper part A of the existing pier 10, the bridge girder 2 is in contact with the upper part A of the existing pier 10. A method (hereinafter referred to as “method [A]”) in which the formed body forming the existing pier 10 is removed from a portion other than the upper surface portion and replaced with a lightweight member 21 that is lighter than the total weight of the removed formed body, for example. As shown in FIG. 3B, a method of forming a through hole 22 in the upper part A of the existing pier 10 (hereinafter referred to as “method [I]”), for example, as shown in FIG. And a method of forming the recess 23 in the upper part A (hereinafter referred to as “method [c]”).

In addition, there is no restriction | limiting in the penetration direction of the through-hole 22, For example, the same direction as the extension direction of the bridge beam 2 may be sufficient, and the horizontal direction orthogonal to the extension direction of the bridge beam 2 may be sufficient.
3C shows an example in which a rectangular parallelepiped concave portion 23 is formed on two opposing side surfaces of the four side surfaces of the existing pier 10, the place where the concave portion 23 is formed, the concave portion 23 The number, the shape of the recess 23 and the like can be changed as appropriate.

Further, the lightweight member 21 used in the method [A] may be a member made of a known material such as a polyurethane resin filled in the entire portion from which the formed body has been removed (see FIG. 3A). A member made of a known material such as steel or fiber reinforced plastic that supports the upper surface portion in contact with the bridge girder 2 may be used. When installing a plurality of members as the lightweight member 21, the total weight of the plurality of members to be installed needs to be lighter than the total weight of the removed formed body.
Moreover, in the example shown to Fig.3 (a)-(c), although the formation body which forms the said existing pier 10 is removed only from the upper part A of the existing pier 10, the gravity center position of the existing pier 10 is lowered | hung. If possible, for example, as shown in FIGS. 3D to 3F, the formed body that forms the existing pier 10 may be removed not only from the upper part A of the existing pier 10 but also from the lower part B.

If the pier obtained by methods [a] to [c] does not have the strength required as a pier, reinforce the part from which the formed body has been removed in order to ensure the strength required as a pier. Is preferred. However, the center of gravity of the pier after reinforcement needs to be positioned below the center of gravity of the existing pier 10.
FIG. 4 is a diagram illustrating an example of a technique for reinforcing the portion from which the formed body has been removed.

  In the case of the pier obtained by the methods [A] to [U], for example, as shown in FIG. It can reinforce by fixing using (not shown). As the belt-like member 24, for example, a member made of a known material such as steel or fiber reinforced plastic can be used.

Further, in the case of the pier obtained by the method [A], for example, as shown in FIG. 4B, the through hole 22 can be reinforced by filling it with a filling member 25.
Also in the case of the pier obtained by the method [c], it can be reinforced by filling the recess 23 with the filling member 25.

Further, in the case of the pier obtained by the method [A], for example, as shown in FIG. 4C, it can be reinforced by installing a tension member 26 in the through hole 22. As the tension member 26, for example, a member made of a known material such as steel or fiber-reinforced plastic can be used.
Also in the case of the pier obtained by the method [c], it can be reinforced by installing the tension member 26 in the recess 23.

Further, in the case of the pier obtained by the method [A], for example, as shown in FIG. 4 (d), the opening surface of the through hole 22 can be reinforced by closing it with a plate-like member 27. As the plate-like member 27, for example, a member made of a known material such as steel, concrete, or fiber reinforced plastic can be used.
Also in the case of the pier obtained by the method [c], it can be reinforced by closing the opening surface of the recess 23 with the plate-like member 27.

The method of removing a part of the formed body that forms the existing pier 10 from at least the upper part A of the existing pier 10, the position and size of the part from which the formed body is removed, the method of reinforcing the part from which the formed body has been removed, etc. It can be appropriately selected according to the degree of lowering the gravity center position of the pier 10 (the difference between the gravity center position of the existing pier 10 and the gravity center position of the fall-resistant bridge pier 20).
The degree of lowering the position of the center of gravity of the existing pier 10 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, and the like.

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 technique [A] is employ | adopted as a method of removing a part of formation body which forms the said existing pier 10 from at least the upper part A of the existing pier 10 is demonstrated to an example.
FIG. 5 is a diagram illustrating an example of the procedure of the overturning suppression method when the method [A] is employed.

First, as shown in FIGS. 5A and 5B, the support member S that supports the upper surface portion in contact with the bridge girder 2 is fixed to the existing pier 10 by using a post-construction anchor or the like (not shown). 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.
Next, as shown in FIG. 5B, a notch K is made using a wire saw or the like at the boundary between the portion where the formed body is removed and the portion where the formed body is not removed.
Next, as shown in FIG. 5C, a part of the formed body is removed from the upper part A of the existing pier 10.
And as shown in FIG.5 (d), the lightweight member 21 is installed in the part which removed the formation body, if necessary, the part which removed the formation body is reinforced, and the support member S is removed. In this way, the existing pier 10 can be changed to the fall-resistant pier 20.

  If the center of gravity of the pier before the installation of the lightweight member 21 in the portion from which the formed body has been removed, that is, the stage of FIG. 5C, is located below the center of gravity of the existing pier 10, FIG. The bridge pier at the stage 5 (c) can be the tip-resistant pier 20, and the installation of the lightweight member 21 and the removal of the support member S can be omitted.

  According to the overturning suppression method of the first embodiment described above, the overturning suppression method makes it difficult to overturn the existing pier 10 directly provided on the ground, and is configured to lower the position of the center of gravity of the existing pier 10. .

  Therefore, since only the position of the center of gravity of the existing pier 10 is lowered, inexpensive and safe construction is possible, and the construction period can be shortened.

  Moreover, according to the fall control method of 1st Embodiment, the formation body (in the case of this embodiment, unreinforced concrete) which forms the said existing pier 10 from the part (upper part A) above the gravity center of the existing pier 10 at least. ) Is removed, the center of gravity of the existing pier 10 can be lowered.

By configuring in this way, at least a part of the formed body forming the existing pier 10 is removed from a portion (upper part A) above the center of gravity of the existing pier 10, so that inexpensive and safe construction is possible. In addition, the construction period can be shortened.
Specifically, since only a part of the forming body forming the existing pier 10 is removed from at least the portion above the center of gravity of the existing pier 10 (upper part A), reinforcement during construction is unnecessary or small-scale. Reinforcement is enough. 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.
Further, by removing a part of the forming body that forms the existing pier 10, the weight of the entire pier becomes smaller than the weight before the removal, so that the reinforcement of the foundation becomes unnecessary and inexpensive construction is possible.
In addition, when the existing pier 10 is installed in a river or the sea, at least a part of the forming body that forms the existing pier 10 is removed from a portion (upper part A) above the center of gravity of the existing pier 10. But you can work on the water. 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. Problems such as inability to secure will occur, but at least the part of the formation that forms the existing pier 10 is removed from the upper part (upper part A) above the center of gravity of the existing pier 10, so it affects the track (track) Construction that is not done becomes possible.

  Moreover, according to the fall prevention construction method of 1st Embodiment, it is comprised so that a part of formation body (in this embodiment unreinforced concrete) may be removed in the range which can ensure intensity | strength required as a bridge pier. Is possible.

By comprising in this way, it can use as a pier as it is only by removing a part of formation body which forms the said existing pier 10 from the part (upper part A) above the gravity center of the existing pier 10 at least. Further, since reinforcement for securing the necessary strength as a bridge pier is unnecessary, it is possible to perform construction at a lower cost and further shorten the construction period.
Here, the existing pier 10 provided directly on the ground often has a strength that greatly exceeds the strength required for the pier. In such a case, particularly, depending on the position and size of the part from which the formed body is removed, it is possible to ensure the necessary strength as a pier even if the formed body is removed.
In the case where a part of the formed body is removed within a range in which a necessary strength as a pier can be secured, as a method of removing a part of the formed body that forms the existing pier 10 from at least the upper part A of the existing pier 10, for example, a technique [ B) and method [c] are adopted.

  Moreover, according to the fall control method of 1st Embodiment, in order to ensure intensity | strength required as a bridge pier, the reinforcement member (band shape) which reinforces the part from which the formation body (in this embodiment, unreinforced concrete) was removed. The member 24, the filling member 25, the tension member 26, the plate-like member 27, etc.) are installed, and the total weight of the reinforcing member can be configured to be lighter than the total weight of the removed formed body.

By configuring in this way, when the removal amount of the formed body is large and the strength necessary for the pier cannot be secured, reinforcement for securing the necessary strength as the pier can be performed. Increased freedom.
In addition, not only when it is no longer possible to secure the necessary strength as a pier by removing the formed body, but also when the formed body is removed within a range where the necessary strength can be secured as a pier You may install the reinforcement member which reinforces the made part.

[Second Embodiment]
In the first embodiment, the center of gravity of the existing pier 10 is lowered by reducing the weight of the upper part A of the existing pier 10, but in the second embodiment, the lower part B of the existing pier 10 is increased in weight. The center of gravity of the existing pier 10 is lowered.

FIG. 6 is a diagram illustrating an example of the overturning suppression method according to the second embodiment.
As a method for increasing the weight of the lower part B of the existing pier 10, for example, as shown in FIG. 6A, the weight 31 is fixed to the lower part B of the existing pier 10 using a post-installed anchor or the like (not shown). A method (hereinafter referred to as “method [e]”) can be used.
Further, when the existing pier 10 has a hem-extended shape, not only the method [D], but also the annular member 32 to which the weight 31 is attached as shown in FIG. A method of fixing the weight 31 (hereinafter referred to as “method [e]”) by moving to B and changing from the state of being fitted around the upper part A with play to the side of the lower part B. ) Can also be used.

In the case of the method [e], specifically, for example, a deformable measure member such as a wire rope is wound around the upper part A of the existing pier 10 and both ends of the measure member are joined, and the upper part A can pass through. However, the lower part B is formed in an annular size that cannot pass. This becomes the annular member 32. Then, the weight 31 is attached to the annular member 32, and the annular member 32 to which the weight 31 is attached is dropped and moved from the upper part A of the existing pier 10 to the lower part B. Thereby, since the annular member 32 is hooked on the side surface of the lower part B, the weight 31 can be fixed.
Note that the method [e] is used not only when the existing pier 10 has a flared shape, but also when the side surface of the lower part B of the existing pier 10 has a convex portion on which the annular member 32 can be caught. it can. Further, the annular member 32 is not limited to one formed by a deformable measure-like member, and may be formed from a rigid member that is difficult to deform, such as a steel material.
Further, the number and shape of the weights 31 to be fixed to the existing bridge pier 10 and the places where the weights 31 are fixed are not limited to those shown in FIGS. 6A and 6B and can be changed as appropriate.

  According to the overturning suppression method of the second embodiment described above, the gravity center position of the existing pier 10 is lowered by fixing the weight 31 to at least a portion (lower part B) below the center of gravity of the existing pier 10. It is configured as follows.

Therefore, since the weight 31 is only fixed at least to the portion (lower part B) below the center of gravity of the existing bridge pier 10, inexpensive and safe construction is possible, and the construction period can be shortened.
Specifically, since the weight 31 is only fixed at least to the portion (lower part B) below the center of gravity of the existing bridge pier 10, 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.
Further, since the weight 31 is only fixed at least to the portion (lower part B) below the center of gravity of the existing pier 10, the weight 31 is provided even when the existing pier 10 is installed in a river or the sea. If the work is fixed on the surface of the water, there is no need for large-scale facilities for water shielding, and it is not necessary to consider the safety against water leakage, thus increasing the contact area between the ground and the pier. Compared with the conventional method for preventing overturning such as a construction method, 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 be secured occur, since the weight 31 is only fixed at least to the portion (lower part B) below the center of gravity of the existing pier 10, construction that is not affected by the track (track) becomes possible.

  Moreover, according to the fall prevention construction method of 2nd Embodiment, it is possible to comprise so that the weight 31 may be fixed using a post-construction anchor (illustration omitted).

  With this configuration, the weight 31 can be reliably fixed.

  Moreover, according to the fall control method of 2nd Embodiment, when there exists a convex part in the side surface of the part (lower part B) below the center of gravity of the existing pier 10, or when the existing pier 10 is hem-spread shape. Moves the annular member 32 to which the weight 31 is attached from the upper part (upper part A) to the lower part (lower part B) from the center of gravity of the existing pier 10 so that the upper part (upper part A) is moved. ), The weight 31 can be fixed to the lower portion (lower part B) from the externally fitted state with play.

By comprising in this way, even if it is a case where the existing pier 10 is installed in the river or the sea, the fixing operation | work of the weight 31 can be performed safely.
Specifically, even when the lower part B of the existing pier 10 is underwater, the work of arranging the annular member 32 to which the weight 31 is attached around the pier (for example, the wire rope around the upper part A A deformable cord-like member such as a steel member or a rigid member that is difficult to deform such as a steel material is formed in a ring shape having a size that allows the upper part A to pass but the lower part B cannot pass, and a weight is formed on the formed annular member 32. The weight 31 can be fixed to the lower portion B simply by dropping the annular member 32 to which the weight 31 is attached after the work is performed on the water surface. Therefore, even when the lower part B of the existing pier 10 is in the water, the weight 31 can be fixed on the water surface, so that the weight 31 can be fixed safely.

[Third Embodiment]
It is also possible to combine the first embodiment and the second embodiment.
Specifically, as shown in FIG. 7, a weight 31 may be fixed to the fall-resistant bridge pier 20 obtained by the fall-suppressing construction method of the first embodiment.
The method of removing a part of the forming body that forms the existing pier 10 from at least the upper part A of the existing pier 10 is not limited to the method [A], and may be the method [A]. [C] may be used, or other methods may be used.
Further, the method of fixing the weight 31 may be the method [e], the method [e], or another method.

For the weight 31, at least a part of the removed formed body (in the case of the present embodiment, unreinforced concrete) may be used.
Moreover, after removing a part of the formation body which forms the existing pier 10 from at least the upper part A, the weight 31 is not fixed, but after fixing the weight 31 to the existing pier 10, at least the existing pier from the upper part A. It is also possible to remove a part of the forming body forming 10.

  According to the fall control method of the third embodiment described above, before or after the formed body (in the case of this embodiment, unreinforced concrete) is removed, the portion below the center of gravity of the existing pier 10 (lower part B) In addition, the weight 31 can be configured to be fixed.

  By comprising in this way, since a gravity center position can be lowered | hung further, it becomes possible to make it more difficult to fall.

  Moreover, according to the fall suppression construction method of 3rd Embodiment, it is possible to comprise so that the weight 31 may use at least one part of the removed formation body (in this embodiment, unreinforced concrete).

  By comprising in this way, since the removed formation body can be reused, cheaper construction becomes possible.

  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 pier 24 Band-shaped member (reinforcing member)
25 Filling member (reinforcing member)
26 Strut member (reinforcement member)
27 Plate-shaped member (reinforcing member)
31 Weight 32 Annular member A Upper part (portion above the center of gravity)
B Lower part (the part below the center of gravity)

Claims (3)

A fall prevention method that makes it difficult for the existing piers directly on the ground to fall,
Lowering the center of gravity position of the existing pier by removing a part of the formed body that forms the existing pier from at least the portion above the center of gravity of the existing pier ,
Before or after removal the formed body, the lower portion than the center of gravity of the existing piers tipping suppression method, wherein lock down the weight. Examples weight, tipping suppression method according to claim 1 which comprises using at least part of said removal the formed body. When there is a convex part on the side surface of the lower part of the center of gravity of the existing pier, or when the existing pier has a hem-extended shape, the annular member to which the weight is attached is connected to the center of gravity of the existing pier. The weight is fixed by moving from the upper part to the lower part so that the upper part has a play and is hooked to the lower part. The fall-suppressing construction method according to claim 1 or 2 , characterized in that:

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