JP2016159199A - Sloshing suppression structure in settling pond - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sloshing suppressing structure in a settling pond, in which a sedimentation apparatus is caused to fluctuate together with water by the sloshing of water in a settling pond at the time of a large-scale earthquake so that the sedimentation apparatus can be prevented from any damage.SOLUTION: In a settling pond 1 having a rectangle planar shape, there is suspended a sedimentation apparatus 2 constituted by holding a number of sedimentation ramps 22 in parallel in a rectangular parallelepiped frame 21, and a shock absorber 3 is interposed between the frame 21 positioned at the end part in the parallel direction of the sedimentation ramp 22 of that sedimentation apparatus 2 and the side wall of the settling pond 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an improvement of a sedimentation basin in a water purification plant or the like, and more particularly to a sloshing suppression structure in a sedimentation basin installed by suspending a sedimentation device using a sedimentation inclined plate.

  Conventionally, in a sedimentation basin in a water purification plant or the like, a sedimentation device using a sedimentation inclined plate is suspended and installed in order to improve the sedimentation efficiency of solids contained in the inflowing water (for example, patent document) 1).

As shown in FIG. 3, the settling device using the settling inclined plate includes a settling basin 1 having a rectangular planar shape, a vertical support material 21 a and a horizontal support material 21 b that constitute an end surface portion of the settling device 2, and a settling device. A rectangular parallelepiped lattice-like frame 21 is formed by two horizontal support members 21c in the longitudinal direction, and a large number of settling inclined plates 22 are held in parallel in this frame 21 in this way. The constructed sedimentation device 2 is suspended and installed via a suspension member 24 on a girder 23 that extends over the sedimentation basin 1.
Then, the water flow direction is set in the longitudinal direction of the settling basin 1, the settling device 2 is set so that the surface of the settling inclined plate 22 is parallel to the water flow direction, and the unit of the settling device 2 is set in the longitudinal direction of the settling basin 1. A plurality of them are installed side by side.
Here, the vertical support member 21a, the horizontal support member 21b, the horizontal support member 21c, and the suspension member 24 constituting the frame 21 are made of a metal material having corrosion resistance such as stainless steel, and the settling inclined plate 22 is made of polyvinyl chloride. It is made of a synthetic resin material such as resin.
Moreover, in order to prevent water from short-circuiting from the gap between the settling device 2 and the side wall of the settling basin 1 on the end surface portion of the settling device 2, a side portion made of a rubber sheet member that closes the gap. A baffle plate 25 is provided.

JP 2001-321607 A

By the way, the sedimentation device 2 using the above-described conventional sedimentation inclined plate 22 is simply suspended and installed on the girders 23 spanned above the sedimentation basin 1 via the suspension members 24. Since it is not constrained in water, it means that the water in the sedimentation basin 1 is sloshing during large-scale earthquakes. Or the liquid overflows from the container, etc.), the sedimentation device 2 swings with water, the sedimentation inclined plate 22 falls from the frame 21 and is damaged, or the frame 21 is damaged. An accident occurred.
In this case, the water treatment capacity of the most important water treatment plant as a lifeline is reduced, or it is necessary to stop the water treatment treatment for repair work. It was.

  In view of the problems of the settling device using the above-described conventional settling inclined plate, the present invention shows that the settling device swings with the water due to the sloshing of the water in the settling pond during a large-scale earthquake, and the settling device is damaged. An object of the present invention is to provide a sloshing suppression structure in a sedimentation basin that can be prevented.

  In order to achieve the above object, the sloshing suppression structure in the sedimentation basin of the present invention is configured by holding a large number of sedimentation inclined plates in parallel with a rectangular parallelepiped frame in a rectangular sedimentation basin. The settling device is suspended and installed, and a shock absorber is interposed between the frame located at the end in the parallel direction of the settling inclined plate of the settling device and the side wall of the settling basin. .

  In this case, the shock absorber can be made of a coil spring member or a rubber-like elastic member.

  Further, the coil spring member may be made of a coil spring member made of low yield point steel having elastic-plastic characteristics.

  In the settling basin, the water flow direction is set in the longitudinal direction of the settling basin, and the settling device can be installed so that the surface of the settling inclined plate is parallel to the water flow direction.

The sloshing suppression structure in the sedimentation basin of the present invention is a sedimentation device constructed by holding a number of sedimentation inclined plates in parallel in parallel with a rectangular parallelepiped frame suspended from a rectangular sedimentation basin. By installing a shock absorber between the frame located at the end in the parallel direction of the sloping inclined plate and the side wall of the sedimentation basin, the shock absorber is settling by the sloshing of water in the sedimentation basin during a large earthquake. When rocking with water, it exerts a buffering action (provides a resistance through the sedimentation inclined plate of the sedimentation device), so that the water in the sedimentation basin can be prevented from sloshing.
This prevents the settling device from swaying with the water due to the sloshing of the water in the settling pond during a large-scale earthquake, preventing the settling device from being damaged, and the water treatment capacity of the most important water purification plant as a lifeline. It is possible to prevent the water purification treatment from being stopped due to a decrease or repair work.

  In addition, the shock absorber can be configured with a device having a simple structure by being made of a coil spring member or a rubber-like elastic member, and can easily cope with newly installed and existing facilities. Can do.

  Further, by making the coil spring member a coil spring member made of low yield point steel having elasto-plastic characteristics, the energy absorption performance by the shock absorber can be improved, and the water in the settling basin causes sloshing. This can be suppressed more reliably.

  In addition, the sedimentation basin has a water flow direction in the longitudinal direction of the sedimentation basin, and the sedimentation device is installed so that the surface of the sedimentation inclined plate is parallel to the water flow direction. It is possible to easily cope with existing facilities.

The test apparatus of the sloshing suppression structure in the sedimentation basin of this invention is shown, (a) is a perspective view, (b) is explanatory drawing of the coil spring member as a buffering device, (c) is the rubber-like elastic member as a buffering device. It is explanatory drawing. (A) of the test apparatus is a front sectional view, and (b) is a plan view. It is explanatory drawing of the sedimentation basin which suspended and installed the sedimentation apparatus using the conventional sedimentation inclination board. It is a graph which shows the restoring force characteristic of the coil spring member made from the low yield point steel which has an elastoplastic property.

  Hereinafter, an embodiment of a sloshing suppression structure in a sedimentation basin of the present invention will be described based on the drawings.

1-2, the test apparatus of the sloshing suppression structure in the sedimentation basin of this invention is shown.
This test apparatus is configured to cut out a part of the settling basin 1 (one unit of the settling apparatus 2) installed by suspending the settling apparatus 2 using the conventional settling inclined plate 22 shown in FIG. 3, the water flow direction is set in the longitudinal direction of the settling tank 1, and the settling device 2 is set in the longitudinal direction of the settling tank 1 so that the surface of the settling inclined plate 22 is parallel to the water flow direction. The present invention can be applied as it is to the conventional sedimentation basin 1 in which a plurality of units of the apparatus 2 are installed side by side.

  The sloshing suppression structure in the settling basin includes a settling device 2 configured by holding a large number of settling inclined plates 22 in parallel with a rectangular parallelepiped frame 21 in a rectangular settling pond 1. The shock absorber 3 is interposed between the frame 21 located at the end in the parallel direction of the sedimentation inclined plate 22 of the sedimentation device 2 and the side wall of the sedimentation basin 1.

In this case, the shock absorber 3 includes a coil spring member 31 as shown in FIG. 1B, more specifically, a coil spring member 31 made of low yield point steel having elastic-plastic characteristics, and FIG. A rubber-like elastic member 33 as shown in (c) can be used.
In particular, by using a coil spring member made of a mild steel (SWRM) wire, which is a low yield point steel having elasto-plastic characteristics, as the coil spring member 31, energy absorption performance by the shock absorber can be enhanced.
Here, a coil spring member made of a mild steel (SWRM) wire, which is a low yield point steel having elastoplastic properties, has an elastic characteristic range (displacement of 10 mm or less) as shown in the graph showing the restoring force characteristics in FIG. ) And a plastic characteristic region (displacement is 10 to 30 mm). In the elastic property region, mainly, a buffering effect is exhibited, and in the plastic property region, mainly an energy absorbing effect is exhibited.

Then, the coil spring member 31 and the rubber-like elastic member 33 as the shock absorber 3 are attached to the four corners of the frame 21 constituting the end surface portion of the settling device 2 facing the side wall of the settling basin 1.
Moreover, the attachment method of the coil spring member 31 or the rubber-like elastic member 33 is such that the base end side is attached to the frame 21 of the settling device 2 via the end plate 32 or the attachment portion 34, and the distal end side is attached to the end plate. 32 or directly or in close contact with the side wall of the settling basin 1 (when the water in the settling basin causes sloshing, the position is in contact with the side wall of the settling basin 1). It is attached to the side wall of the sedimentation basin 1 through the end plate 32.
The mounting position and number of the shock absorbers 3 and the mounting method thereof are not limited to this. For example, the shock absorbers 3 are arranged on the frame 21 4 constituting the end surface portion of the settling device 2 facing the side wall of the settling basin 1. In addition to the corner, it can also be attached at an intermediate position.

The sloshing suppression structure in the sedimentation basin is a sedimentation device constructed by holding a large number of sedimentation inclined plates 22 in parallel in a rectangular parallelepiped frame 21 suspended from the sedimentation basin 1 having a rectangular planar shape. When the shock absorber 3 is interposed between the frame 21 located at the end in the parallel direction of the two sloping inclined plates 22 and the side wall of the sedimentation basin 1, the shock absorber 3 can be used in the case of a large-scale earthquake. When the settling device 2 swings together with the water due to the sloshing of the water in 1, a buffering action is exerted (a resistance force is applied via the settling inclined plate 22 of the settling device 2), so that the water in the settling basin 1 is sloshing. Can be suppressed.
As a result, it is possible to prevent the sedimentation device 2 from oscillating together with the water due to the sloshing of the water in the sedimentation basin 1 during a large-scale earthquake, and to prevent the sedimentation device 2 from being damaged. It is possible to eliminate the need to stop the water purification treatment due to a decrease in the water treatment capacity or for repair work.

  Next, a description will be given of the results of tests performed using the test apparatus for the sloshing suppression structure in the sedimentation basin shown in FIGS.

[Experimental conditions]
The water tank 1 of the test apparatus corresponding to the sedimentation basin 1 was a rectangular planar shape having a width of 2.10 m, a depth of 1.4 m, and a height of 1.4 m, and the water depth was set to 1.0 m.
The shaking table 4 used for excitation is an acceleration control type shaking table (table size: 3 m × 2 m, frequency range: 0.5 Hz to 30 Hz, mounting weight: 4000 kg).

In this experiment, when only water is put in the water tank 1 (Case 1), when the sedimentation device 2 is installed in the water tank 1 (Case 2), the sedimentation device 2 is installed in the water tank 1, and the buffer device 3 is installed in the sedimentation device 2. Experiments were conducted in five cases where the coil spring member 31 was attached (Case 3 and Case 4) and when the rubber-like elastic member 33 was attached (Case 5).
Here, the coil spring member 31 is a coil spring member made of mild steel (SWRM) wire, which is a low yield point steel having elasto-plastic characteristics, as shown in Table 1. Rubber (manufactured by Kurashiki Processing Co., Ltd., model number: RI-25HD, maximum stroke: 11 mm, maximum absorbed energy: 8.8 J) was used.

The coil spring member 31 and the rubber-like elastic member 33 as the shock absorber 3 are attached to the four corners on both sides of the frame 21 constituting the end surface portion of the settling device 2 facing the side wall of the water tank 1.
The attachment method of the coil spring member 31 is such that the base end side is attached to the frame 21 of the settling device 2 via the end plate 32 and the tip end side is attached to the side wall of the water tank 1 via the end plate 32. I made it.
The attaching method of the rubber-like elastic member 33 is such that the base end side is attached to the frame 21 of the sedimentation device 2 via the attaching portion 34, and the tip end side is in direct contact with the side wall of the water tank 1.

[experimental method]
The shaking of the shaking table 4 caused sloshing in the water in the water tank 1, and the wave height, hydrodynamic pressure, and displacement of the frame 21 of the settling device 2 were measured, and the effect of suppressing sloshing was measured from the results.
Here, a float-type liquid level gauge is used for measuring the wave height, and the displacement in the vertical direction of the float is defined as the displacement of the wave height. For the displacement of the float, a potentiometer type displacement transducer (rated capacity: 0 to 500 mm) is used.
For measurement of dynamic water pressure, a small pore pressure hydrometer (rated capacity: 50 kPa) is used, and the measurement positions are water depths of 0.12 m, 0.32 m, and 0.52 m, respectively. The dynamic water pressure was set to 0 kPa before vibration with water.
The displacement of the frame 21 of the settling device 2 was measured by attaching a potentiometer displacement transducer (rated capacity: 0-500 mm) to the water tank 1 side.

[experimental method]
In this experiment, the sloshing of the primary mode was targeted.
The sloshing natural frequency of the first-order mode of the experimental model is 0.58 Hz from the equation (1) based on the velocity potential theory. In the equation (1), f is the natural frequency of the sloshing mode in the first-order mode, g is the gravitational acceleration, h is the water depth, and a is 1/2 the width of the water tank 1 in the sloshing direction.
f = ((1.58 g / a) tanh (1.58 g / a)) ^1/2 / 2π (1)
Excitation by the vibration table 4 was sine wave excitation, and was performed at a frequency of 0.50 to 2.00 Hz.
In Case 1, excitation was performed in increments of 0.01 Hz for 0.50 to 0.70 Hz, in increments of 0.05 Hz for 0.70 to 1.0 Hz, and in increments of 0.1 Hz for 1.0 to 1.5 Hz. In Case 2 to Case 5, 0.50 to 0.60 Hz is incremented by 0.01 Hz, 0.60 to 0.70 Hz is incremented by 0.02 Hz, 0.70 to 0.80 Hz is incremented by 0.05 Hz, and 0.80 to 1.00 Hz. Was excited in increments of 0.1 Hz, and 1.0 to 2.0 Hz in steps of 0.5 Hz.
Target input acceleration, in Case1 and Case2, and 0.25 m / ^{s 2,} the Case3～Case5, was 0.25 m / ^{s 2} and 0.5 m / ^{s 2.} This is because it is considered that water does not overflow from the water tank 1 due to sloshing.

[Experimental results and discussion]
The experimental results are shown in Table 2.

  As is clear from Table 2, all values of maximum liquid level displacement, maximum pressure, frame acceleration and frame displacement are obtained when water is added to the water tank 1 (Case 1) and when the sedimentation device 2 is installed in the water tank 1 ( More than Case 2), when the settling device 2 is installed in the water tank 1 and the coil spring member 31 as the buffer device 3 is attached to the settling device 2 (Case 3 and Case 4), when the rubber-like elastic member 33 is attached (Case 5) However, when the same coil spring member 31 was attached (Case 3 and Case 4), it was confirmed that Case 4 (wire diameter φ4) having a large wire diameter of the coil spring member 31 has a large effect of suppressing sloshing.

  As mentioned above, although the sloshing suppression structure in the sedimentation basin of this invention was demonstrated based on the embodiment, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning, the structure is changed suitably. It is something that can be done.

  The sloshing suppression structure in the settling basin of the present invention can prevent the settling device from being damaged by sloshing of the water in the settling basin due to the sloshing of the water in the settling basin, so that the settling device is damaged. It can be suitably applied to a settling basin in a water purification plant or the like installed by suspending the used settling device.

1 Sedimentation basin (water tank)
2 Sedimentation device 21 Frame 21a Vertical support material 21b Horizontal support material 21c Horizontal support material 22 Sinking inclined plate 23 Girder material 24 Suspension member 3 Shock absorber 31 Coil spring member 32 End plate 33 Rubber elastic member 34 Attachment

Claims (5)

  A settling device constructed by holding a large number of settling inclined plates parallel to a rectangular parallelepiped frame in a rectangular sedimentation basin is installed in a suspended manner. A sloshing suppression structure in a sedimentation basin, characterized in that a shock absorber is interposed between a frame located at an end in the parallel direction and a side wall of the sedimentation basin.   The sloshing suppression structure in a sedimentation basin according to claim 1, wherein the shock absorber is a coil spring member.   The sloshing suppression structure in a sedimentation basin according to claim 2, wherein the coil spring member is a coil spring member made of low yield point steel having elastic-plastic characteristics.   The sloshing suppression structure in a sedimentation basin according to claim 1, wherein the shock absorber is made of a rubber-like elastic member.   The sedimentation basin has a water flow direction set in the longitudinal direction of the sedimentation basin, and the sedimentation device is installed so that the surface of the sedimentation inclined plate is parallel to the water flow direction. The sloshing suppression structure in the settling basin according to 3 or 4.

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