JP4721358B2 - Removal structure of driftwood in bridge - Google Patents

Description

  The present invention relates to a structure for removing driftwood from a bridge.

In recent years, the amount of driftwood has increased, and there has been a problem that driftwood has caught on bridge girders.
If driftwood flows out and gets caught on the bridge girder, there is a risk of destruction of the bridge.
Furthermore, since the flow of water is hindered by the driftwood group, the water will increase and overflow to both banks will occur.
This overtopping has resulted in the destruction of the road, and the outflow and destruction of private houses on both sides, leading to personal injury.
In order to prevent the driftwood from being caught on the bridge girder, conventionally, the driftwood is guided to the reservoir and collected before the driftwood collides with the bridge (Patent Document 1). The structure which captures with the support | pillar group of (patent document 2) is known.

JP-A-8-302653. JP-A-9-105122.

The conventional driftwood removal structure in the bridge as described above is uneconomical in that it is necessary to provide a reservoir separately from the mainstream of the river, or to establish a large number of strong support groups on the riverbed.

In order to solve the problems as described above, in the bridge of the present invention in the driftwood removal structure, in the bridge crossing the river flow flowing from the upstream to the downstream , the control material is attached to the upstream side surface of the bridge. configured, the control member is a rod-shaped body attached substantially parallel to the direction of flow, and is attached at an upward angle to the horizontal plane, is driftwood that has flowed down in a state of substantially parallel to the flow control member It features a structure for removing driftwood from a bridge, which is constructed by attaching a plurality of bridges with an interval between them.

Since the structure for removing driftwood in the bridge of the present invention is as described above, the following effects can be obtained.
<1> It does not require large-scale construction such as providing a reservoir separately from the main stream of the river, and it can economically prevent trapping of driftwood.
<2> Rather than establishing a large number of struts on the riverbed and forcibly blocking the flow of driftwood, it will flow down flexibly, so that it does not require a very strong facility.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

<1> Precondition.
The structure of the present invention functions when the water level is close to the lower surface of the bridge 1 or flows over the upper surface of the bridge 1.
And the structure of this invention is a structure which does not capture or collect | recover the driftwood which flows from an upstream in such a case, but flows down downstream from the bridge 1 toward the downstream.

<2> Attaching the control material 2.
A plurality of control members 2 are attached to the upstream side surface of the bridge 1.
The control material 2 is a steel rod having a certain length.
The lower end of the control member 2 is attached directly to the lower edge of the bridge 1 by welding or bolted via a bracket or the like.
The plurality of control members 2 are attached substantially parallel to the flow direction.
In addition, it is possible to maintain the strength by attaching a rod-like body in a direction substantially perpendicular to the flow direction to the control material 2 group attached substantially in parallel with the flow direction to form a lattice shape.
The control material 2 is not limited to a rod-shaped body having a circular cross section, but also includes a rod-shaped body having a square cross section, a rectangular cross section, and a polygon cross section.

<3> The mounting angle of the control material 2.
The control member 2 is attached at an angle upward with respect to the horizontal plane.
For example, the control member 2 is attached at an angle of approximately 45 degrees with respect to the horizontal plane.

<4> Flowing state of driftwood.
Driftwood can be divided as follows.
That is, the flow flows with the upper and lower ends of the driftwood positioned parallel to the flow, the flow with the upper and lower ends positioned in a direction perpendicular to the flow, and the flow flows at an intermediate angle.

<5> Guidance by the control material 2
In the event of a flood, before the driftwood collides with the upstream side surface of the bridge 1, the driftwood collides from the upstream side with a plurality of control members 2 mounted at an angle upward to the horizontal plane and substantially parallel to the flow direction .
In the driftwood, the driftwood that has flowed down in a state substantially parallel to the flow passes between the control members 2 and flows downstream, and does not get caught in the bridge 1.
The driftwood that has flowed down in a state substantially orthogonal to the flow collides with the control material 2.
However, as described above, the control material 2 group is attached to the upstream side of the bridge 1 at an upward angle with respect to the horizontal plane.
For this purpose, the driftwood is subjected to a force that simultaneously impinges on the plurality of control members 2 and is pushed into the water.
As a result, the driftwood is pushed into the lower surface of the bridge 1 and passes along the lower surface of the bridge 1 along with the water flow and flows downward.
The driftwood flowing down at an intermediate angle between the two collides with the control member 2 sequentially from the preceding downstream position, and the angle is changed to a posture perpendicular to the direction of the flow, and is pushed into the lower surface of the bridge 1, At the same time, it passes through the lower surface of the bridge 1 and flows downward.
Thus, the driftwood flowing down at any angle will flow downstream without being caught by the bridge 1.

<6> From hydraulic experiments. (Fig. 4)
The hydraulic experiment confirmed the effect of preventing the driftwood from being caught by attaching a plurality of control members 2 to the bridge girder.
An embodiment of the bridge 1 in which the equipment of the present invention is installed has the configuration shown in FIGS.
On the other hand, a normal bridge 1 has a configuration shown in FIG.
As a result, as shown in FIG. 4, in the configuration of the present invention, the number of catches is zero at any flow strength (Fr).
On the other hand, up to 13 catches could be confirmed in the conventional bridge 1 in which the facility of the present invention was not installed.

<7> Relationship with external force at the time of collision. (Figs. 5 and 6)
When a driftwood that should collide with the bridge 1 by attaching the control material 2 is caused to flow downward under the bridge 1 by applying a downward pushing force before the collision, the external force exerts a large horizontal force on the bridge 1, The possibility of acting as a vertical force is also conceivable.
If the bridge 1 itself seems to be damaged by such an external force, it is contrary to the object of the present invention.
Therefore, it was confirmed by hydraulic experiment how much external force, that is, horizontal force and vertical force was applied.
As a result, the horizontal force acting on the bridge 1 is shown in FIG. 5, and the vertical force acting on the bridge 1 is shown in FIG. 6. In each case, the numerical value almost the same as that of the bridge 1 without the control member 2 is obtained. I was able to.
That is, even if the control material 2 group is attached to the upstream side surface of the bridge 1 and the driftwood collides with the control material 2 group, the influence on the bridge 1 is almost the same as the case of the normal bridge 1 without the control material 2 attached. It turned out to be the same.

Explanatory drawing of the example of the model in the hydraulic experiment of the removal structure of the driftwood in the bridge of this invention. The explanatory view which looked at the model of Drawing 1 from other angles. The figure which showed the catch state of the driftwood in the conventional bridge in hydraulic experiment. The figure which compared the number of catches of driftwood in the bridge which provided the removal structure of driftwood, and the bridge which is not provided. The figure which shows the horizontal force which acts on a bridge in the model in a hydraulic experiment. The figure which shows the vertical force which acts on a bridge in the model in a hydraulic experiment.

Explanation of symbols

1: Bridge 2: Control material

Claims (3)

In a bridge that crosses the river flow from upstream to downstream ,
A control material is attached to the upstream side of the bridge .
The control material is
It is a rod-like body attached almost parallel to the direction of flow,
And with an upward angle with respect to the horizontal plane,
The driftwood that flowed down in a state of being almost parallel to the flow was constructed by attaching multiple pieces through the interval that can pass between the control materials ,
Removal structure of driftwood in bridges. The structure for removing driftwood from a bridge according to claim 1,
The lower end of the control material was attached along the lower edge of the bridge girder,
Removal structure of driftwood in bridges. The structure for removing driftwood from a bridge according to claim 1,
The control material was attached at an angle of approximately 45 degrees to the horizontal plane.
Removal structure of driftwood in bridges.

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