Fluid discharge mechanism and centrifugal model experimental apparatus

Abstract

The objective is to supply fluid to the model economically and reliably. [Solution] The system comprises a fluid holding device that holds a fluid under pressure, and a perforated pipe that releases the fluid supplied from the fluid holding device into a model.

Description

Technical Field

[0001] The present invention relates to a fluid discharge mechanism for discharging fluid to a model and a centrifuge model experiment device provided with the fluid discharge mechanism.

Background Art

[0002] Conventionally, when it is difficult to conduct full-scale experiments such as elucidating the complex behavior of ground, soil structures, foundation structures, etc. and the disaster mechanisms caused by earthquakes, etc., for example, a centrifuge model experiment using a centrifuge model experiment device (centrifugal force loading test device) as disclosed in Patent Document 1 has been carried out. A centrifuge model experiment device is a device that can obtain results faithful to full-scale experiments by applying a centrifugal acceleration corresponding to its scale to a scale model.

[0003] In recent years, not only earthquakes but also the number of occurrences of landslide disasters has increased due to the occurrence of concentrated heavy rain. Therefore, it is desired to develop a method that can clarify the behavior of interstitial water in the ground during and after rainfall, evaluate the stability of the ground, and further enable the study of countermeasures through experiments using a centrifuge model experiment device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to reproduce rainfall on a scale model of the ground, for example, there is a method of arranging a sprinkler nozzle above the scale model and sprinkling water using this nozzle. In this case, pressurized water is supplied to the nozzle, but in order to satisfy the similarity law between the droplets ejected from the nozzle and raindrops, it is necessary to adjust the particle size of the droplets to about several tens to several hundreds of μm, and the pressure of the water supplied to the nozzle is required to be higher.

[0006] While procuring high-pressure water is possible by preparing a water tank and equipment such as pumps and air compressors, it is difficult to mount these on a centrifugal model experimental apparatus. Even if it were possible to mount them, since centrifugal force fields reaching 30G to 50G are generally set to increase the similarity ratio, the apparatus may not be able to perform as expected in such a high-gravity environment, or it may even be damaged.

[0007] Therefore, while a water tank is installed in the centrifugal model experimental apparatus, a method is often adopted in which equipment capable of supplying air pressure is prepared outside the centrifugal model experimental apparatus, and the water supplied from the outside is pressurized (back pressure) with the air pressure supplied from the outside. However, adding such equipment to supply air pressure from the outside requires extensive modifications to the centrifugal model experimental apparatus, which has been a challenge in terms of time and cost.

[0008] This invention has been made in view of the above problems, and its main objective is to release fluid into a model economically and stably. [Means for solving the problem]

[0009] To achieve this objective, the fluid discharge mechanism of the present invention is characterized by comprising a fluid holding device that holds a fluid under pressure, and a perforated pipe that discharges the fluid supplied from the fluid holding device onto a model.

[0010] The fluid discharge mechanism of the present invention is such that the fluid holding device is an accumulator, and the fluid may be a liquid stored in the accumulator.

[0011] The fluid discharge mechanism of the present invention may be provided with an injection nozzle in the perforated pipe.

[0012] The fluid discharge mechanism of the present invention comprises a connecting pipe that connects the perforated pipe and the fluid holding device, and the connecting pipe may be provided with a pressure adjustment mechanism that adjusts the pressure of the fluid flowing in from the fluid holding device and supplies it to the perforated pipe.

[0013] The fluid discharge mechanism of the present invention may also include an on-off valve in the connecting pipe.

[0014] The centrifugal model experimental apparatus of the present invention includes a rotating device that rotates around a vertical axis, and a storage container for storing a model that is installed on the rotating device in a state that allows it to swing around a horizontal axis, and the fluid discharge mechanism is installed on the storage container.

[0015] According to the fluid discharge mechanism and centrifugal model experimental apparatus of the present invention, the fluid discharge mechanism is equipped with a fluid holding device, such as an accumulator, capable of holding the fluid under pressure. This allows the fluid to be procured under pressure within the fluid discharge mechanism and supplied to a perforated pipe for discharge towards the model without using any power.

[0016] This allows for the installation of a perforated pipe in the storage container that houses the model, and the fluid retention device to be positioned close to the storage container or a rotating arm, for example, when releasing fluid into the model during centrifugal model experiments. Therefore, it becomes possible to release fluid into the model economically and stably without making major modifications to the centrifugal model experimental apparatus. Furthermore, the fluid released from the perforated pipe can be either a liquid or a gas, making it applicable to a variety of uses.

[0017] Furthermore, for example, when simulating rainfall by installing a spray nozzle on a perforated pipe and performing watering, the liquid held under pressure in the fluid holding device can be supplied to the perforated pipe at a constant pressure by adjusting the pressure using a pressure adjustment mechanism, allowing the supplied liquid to be sprayed in a mist. In addition, by adjusting the pressure using the pressure adjustment mechanism, it is possible to adjust the particle size of the droplets sprayed from the spray nozzle to satisfy the similarity law with that of raindrops, thereby faithfully reproducing actual rainfall. This makes it possible to clarify the behavior of the ground and pore water in the ground under rainfall with higher accuracy, and improves the reliability of centrifugal model experiments.

[0018] In addition, if a storage container storing a reduced-scale model is equipped with a shaking table or the like that reproduces an earthquake, it is also possible to reproduce a phenomenon in which a plurality of natural disasters such as an earthquake and heavy rain occur simultaneously or successively. Thus, since the scope of application of the centrifugal model experiment is expanded, it can contribute to the study and development of countermeasures for various natural disaster risks.

Effects of the Invention

[0019] According to the present invention, since the fluid holding device that holds the fluid in a pressurized state is provided in the fluid discharging mechanism, for example, even when performing a centrifugal model experiment or the like, it is possible to economically and stably discharge the fluid to the model without performing a large-scale modification of the centrifugal model experiment device.

Brief Description of the Drawings

[0020] [Figure 1] It is a diagram showing an example of a centrifugal model experiment device in an embodiment of the present invention. [Figure 2] It is a diagram showing an example of a static bucket and a dynamic bucket in an embodiment of the present invention. [Figure 3] It is a diagram showing a fluid discharging mechanism in an embodiment of the present invention. [Figure 4] It is a diagram showing a state of an accumulator and a liquid in an embodiment of the present invention. [Figure 5] It is a diagram showing another example (No. 1) of the fluid discharging mechanism in an embodiment of the present invention. [Figure 6] It is a diagram showing another example (No. 2) of the fluid discharging mechanism in an embodiment of the present invention.

Modes for Carrying Out the Invention

[0021] The present invention aims to reproduce various natural phenomena by discharging a fluid such as a liquid or a gas toward a model of the ground, a structure, or the like. In this embodiment, as an example, a case where rainfall is reproduced by a fluid discharging mechanism on a ground model mounted on a centrifugal model experiment device will be described in detail.

[0022] Before explaining the details of the fluid discharge mechanism, we will describe the centrifugal model experimental apparatus, the storage container, and the ground model. Note that the centrifugal model experimental apparatus shown in Figure 1 is just one example and is not the only one that can be used.

[0023] <<Centrifugal Model Experiment Apparatus>> As shown in Figures 1(a) and (b), the centrifugal model experimental apparatus 10 comprises a rotating device 11 and a pair of buckets 12.

[0024] As shown in Figure 1(a), the rotating device 11 comprises a rotating arm 111 extending horizontally, a vertical shaft 112 passing through the center of the rotating arm 111, and a drive mechanism 113 that rotates the vertical shaft 112. In addition, horizontal shafts 114 are provided on both sides of the rotating arm 111, flanking the vertical shaft 112, to support a pair of buckets 12 positioned on each side.

[0025] The horizontal axis 114 is mounted inside the rotating arm 111 in a position perpendicular to the extending direction of the rotating arm 111, and passes through the static bucket 12a and the dynamic bucket 12b. As a result, when the rotating device 11 is stopped, the static bucket 12a and the dynamic bucket 12b hang down in a state where they can swing freely around the horizontal axis 114.

[0026] On the other hand, when the drive mechanism 113 is activated and the rotating device 11 starts operating, the vertical shaft 112 rotates, and the rotating arm 111 fixed to it also rotates. As the rotational speed of the rotating arm 111 increases, the static bucket 12a and the dynamic bucket 12b gradually swing upward around the horizontal shaft 114.

[0027] When the rotational speed of the rotating arm 111 reaches a predetermined value, the raised static bucket 12a and dynamic bucket 12b assume a horizontal position, as shown in Figure 1(b), and a predetermined centrifugal force acts upon them. Models are then placed inside either one or both of the static bucket 12a and dynamic bucket 12b, which are subjected to this centrifugal force.

[0028] Figure 2 illustrates a case in which a soil tank 40 containing a ground model 30 is housed in the internal cavity of a static bucket 12a. The static bucket 12a is a case with sufficient area and volume to house the soil tank 40 containing the ground model 30, and the soil tank 40 is installed at the bottom 121.

[0029] The dynamic bucket 12b is a large-capacity case with the same shape as the static bucket 12a, but a shaking table 122 that reproduces seismic motion is mounted at the bottom 121 of its interior. As shown in Figure 5, for example, when a ground model 30 is placed inside the dynamic bucket 12b, the shaking table 122 vibrates the ground model 30 in one direction perpendicular to the direction in which centrifugal gravity acts, in an environment where centrifugal gravity is acting.

[0030] <<Earth tank and ground model>> In this embodiment, the ground model 30 simulates an embankment 32 on the base layer 31, as shown in Figure 2. The soil tank 40 comprises side plates 41 surrounding the ground model 30 on all four sides, and a bottom plate 42 provided below the side plates 41. Since the upper side of the side plates 41 is open, a fluid such as gas or liquid is released into the ground model 30 through this opening by the fluid release mechanism 20.

[0031] ≪≪Fluid release mechanism≫≫ The fluid discharge mechanism 20 is installed on the upper side of the side plate 41 that constitutes the soil tank 40 via a mounting base 50. Its structure can be any such mechanism that can hold the fluid under pressure and discharge the held fluid into the ground model 30.

[0032] Figures 3(a) and (b) illustrate a fluid discharge mechanism 20 capable of reproducing rainfall by holding liquid L in a pressurized state and spraying it in a mist. Such a fluid discharge mechanism 20 comprises a perforated pipe 21 positioned opposite the ground model 30, a fluid holding device 23 for holding liquid L in a pressurized state, and a connecting pipe 22 connecting the perforated pipe 21 and the fluid holding device 23.

[0033] Perforated pipe As shown in Figure 3(a), the perforated pipe 21 is a nozzle piping system in which multiple injection nozzles 212 are attached at intervals to a pipe body 211 having a predetermined inner diameter. The multiple injection nozzles 212 are arranged at predetermined intervals so as to face the ground model 30. There are no restrictions on the arrangement of the perforated pipes 21, but the plan view in Figure 3(b) shows an example where multiple perforated pipes 21 are arranged in parallel in a connected state so that the liquid L supplied from the fluid holding device 23 via the connecting pipe 22 can be sprayed in a mist over the entire surface of the ground model 30.

[0034] <<Connecting pipe>> As shown in Figure 3(a), the connecting pipe 22 comprises a pipe body 221 having a predetermined inner diameter, and a regulator 222 and a solenoid valve 223 installed on the pipe body 221. The regulator 222 adjusts the pressurized liquid L flowing in from the fluid holding device 23 to a desired pressure. The solenoid valve 223 controls the amount of liquid L supplied to the perforated pipe 21. The regulator 222 may be operated manually or remotely, but it is preferable that the solenoid valve 223 has a mechanism that allows for remote operation.

[0035] ≪Fluid holding device≫ Any fluid holding device 23 may be used as long as it has a mechanism capable of holding the fluid under pressure. The following example will explain the case in which an accumulator 24 is used to hold the liquid L under pressure.

[0036] The accumulator 24 may employ any structure available on the market, but Figure 4(a) illustrates one comprising a main body 241 and a membrane 242. Nitrogen gas A is sealed inside the membrane 242 at a predetermined sealing pressure, and when no liquid L is accumulated in the main body 241, the membrane 242 is in close contact with the entire inner wall surface of the main body 241.

[0037] An example of a method for maintaining liquid L in a pressurized state in the accumulator 24 described above is shown below. For example, the connecting pipe 22 is connected to the accumulator 24, and a predetermined amount of liquid L is introduced from the pipe body 221 of the connecting pipe 22 into the body 241 of the accumulator 24 at a pressure higher than the sealing pressure of nitrogen gas A. After this, as shown in Figure 4(b), by closing the solenoid valve 223 of the connecting pipe 22, the nitrogen gas A is compressed and the liquid L is accumulated and held in a pressurized state. Then, as shown in Figure 4(c), when the solenoid valve 223 is opened, the nitrogen gas A expands, and the pressurized liquid L is supplied from the pipe body 221 of the connecting pipe 22 to the perforated pipe 21.

[0038] <<Watering to simulate rainfall>> The fluid discharge mechanism 20, having the above configuration, supplies the liquid L accumulated and held under pressurized conditions in the accumulator 24 to the injection nozzle 212 of the perforated pipe 21, spraying it in a mist to simulate rainfall on the ground model 30. Below, an example of the procedure for simulating rainfall by spraying water in a static bucket 12a during a centrifugal model experiment will be described.

[0039] First, as explained with reference to Figures 4(a) and (b), one end of the connecting pipe 22 is attached to the accumulator 24 before assembling the fluid discharge mechanism 20, and liquid L is introduced through this connecting pipe 22. After a predetermined amount has been introduced, the solenoid valve 223 is closed to store and retain the pressurized liquid L. Next, the perforated pipe 21 is connected to the connecting pipe 22 to assemble the fluid discharge mechanism 20.

[0040] Before and after these operations, the regulator 222 is operated so that the liquid L stored and held under pressurization in the accumulator 24 is supplied to the injection nozzle 212 at the desired pressure. Next, as explained with reference to Figure 3(a), the fluid discharge mechanism 20 is installed on the top of the soil tank 40, which forms the ground model 30 and is placed inside the static bucket 12a, via the installation base 50. The position and orientation of the injection nozzle 212 are also adjusted as appropriate.

[0041] Next, as explained with reference to Figures 1(a) and (b), the static bucket 12a is attached to the rotating device 11 of the centrifugal model experimental apparatus 10, and the drive mechanism 113 is operated to rotate the rotating arm 111. When a predetermined rotational speed is reached, as shown in Figure 2, centrifugal gravity acts on the static bucket 12a toward the bottom 121, and in this state, the solenoid valve 223 of the fluid discharge mechanism 20 is opened by remote control.

[0042] As a result, the liquid L, which has been stored and held under pressurization in the accumulator 24, is regulated in pressure as it passes through the regulator 222 and supplied at a constant pressure from the pipe body 211 of the perforated pipe 21 to the injection nozzle 212. In this way, without using any power, the liquid L simulating rainfall can be sprayed in a mist-like manner from the injection nozzle 212 toward the ground model 30.

[0043] Incidentally, it is widely known that in centrifugal model experiments, if a ground model 30 with a geometric scale of 1 / N is experimented with under centrifugal gravity NG, the same stress and strain fields as the actual ground can be reproduced. Therefore, by adjusting the particle size of the droplets sprayed from the injection nozzle 212 so that this similarity law is satisfied between the actual raindrop diameter (approximately 1000-8000 μm) and the actual raindrop diameter, it becomes possible to faithfully reproduce actual rainfall.

[0044] For example, if a ground model 30 with a geometric scale of 1 / 50 is created, a centrifugal force of 50G is applied to the ground model 30 using the centrifugal model experimental apparatus 10. When watering is performed to simulate rainfall on the ground model 30 subjected to this centrifugal force of 50G, liquid L is supplied to the spray nozzle 212 so that droplets with a particle size of approximately 20 to 160 μm are sprayed from the spray nozzle 212.

[0045] Such droplet particle size adjustment is achieved by adjusting the pressure of the liquid L supplied to the injection nozzle 212. In the fluid discharge mechanism 20, as described above, a regulator 222 is interposed between the accumulator 24 and the perforated pipe 21. Therefore, by appropriately adjusting the pressure of the liquid L supplied to the injection nozzle 212 using the regulator 222, the droplet size of the droplets sprayed from the injection nozzle 212 can be set to any size, making it easy to reproduce real rainfall. Furthermore, it becomes possible to observe the pressure when raindrops hit the ground surface using centrifugal model experiments.

[0046] As described above, according to the present invention, the fluid discharge mechanism 20 is provided with a fluid holding device 23 capable of holding the liquid L in a pressurized state. This allows the pressurized liquid L to be procured within the fluid discharge mechanism 20 and supplied to the perforated pipe 21 without using any power. Furthermore, since large-scale equipment such as pumps and air compressors are not required, it can be mounted in a static bucket 12a where centrifugal gravity acts. Therefore, it becomes possible to spray liquid L simulating rainfall onto the ground model 30 in a mist form economically and stably without modifying the centrifugal model experimental apparatus 10.

[0047] The fluid discharge mechanism 20 and the centrifugal model experimental apparatus 10 equipped with the fluid discharge mechanism 20 of the present invention are not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the spirit of the present invention.

[0048] For example, in this embodiment, the fluid discharge mechanism 20 is mounted on a static bucket 12a, but as shown in Figure 5(a), it may also be mounted on a dynamic bucket 12b. By mounting the ground model 30 and the fluid discharge mechanism 20 on the dynamic bucket 12b, it becomes possible to clarify the behavior of the ground and pore water in the ground when multiple natural disasters such as earthquakes and rainfall occur simultaneously or sequentially. In this way, the scope of centrifugal model experiments is broadened, which can contribute to the study and development of countermeasures against various natural disaster risks.

[0049] Furthermore, although this embodiment uses an accumulator 24 as the fluid holding device 23 as an example, the structure is not limited in any way as long as it has a mechanism that can hold the liquid L under pressure and supply it to the perforated pipe 21. Other examples will be described below with reference to Figure 6.

[0050] As shown in Figure 6(a), the separate liquid holding device 25 comprises two liquid-filled sections 251 and one gas-filled section 252. Liquid L is filled into the liquid-filled sections 251 at a predetermined pressure, and nitrogen gas A is filled into the gas-filled section 252 at a higher pressure than liquid L. These liquid-filled sections 251 and gas-filled section 252 are connected via a connecting pipe 254 equipped with a solenoid valve 253.

[0051] Furthermore, the two liquid-filled sections 251 are connected to the perforated pipe 21 via the connecting pipe 22. Here, as explained with reference to Figure 3(a), the connecting pipe 22 is equipped with a regulator 222 and a solenoid valve 223, and the perforated pipe 21 is equipped with an injection nozzle 212.

[0052] When using the above-described separate liquid holding device 25 to simulate rainfall in a centrifugal model experiment, first, the solenoid valve 253 of the connecting pipe 254 is opened. Then, nitrogen gas A sealed in the gas-filled section 252 flows into the liquid-filled section 251, pressurizing the liquid L via the gate valve 251a.

[0053] In this state, when the solenoid valve 223 of the connecting pipe 22 is opened, the pressurized liquid L is regulated by the regulator 222 and supplied to the perforated pipe 21. This allows the liquid L, which simulates rainfall, to be sprayed in a mist-like manner from the injection nozzle 212 toward the ground model 30.

[0054] Furthermore, the liquid L released can be any liquid commonly used in centrifugal model experiments, such as water or silicone oil used to simulate rainfall, or pH-adjusted solutions used to simulate physical and chemical weathering. If a viscous liquid is used as liquid L, it is advisable to adjust the pressure using regulator 222, taking viscosity into consideration.

[0055] Furthermore, the fluid discharge mechanism 20 can use not only liquid L but also gas as the fluid. Therefore, the fluid discharge mechanism 20 can be applied to various uses, not just the watering that simulates rainfall as described above. When using gas, for example, the gas-filled section 252 described with reference to Figure 6(a) can be used as the fluid holding device 23.

[0056] Furthermore, in this embodiment, a nozzle piping system equipped with a spray nozzle 212 on a perforated pipe 21 is employed, but any configuration that allows liquid L to be discharged and sprayed onto the ground model 30 may be used. For example, as shown in Figure 5(b), multiple insertion holes 213 may be provided at predetermined intervals along the longitudinal direction on the side of the pipe body 211 facing the ground model 30, or a strainer portion 214 such as a mesh or groove may be formed.

[0057] In addition, the fluid discharge mechanism 20 may be structured such that a flexible pipe is used for the pipe body 221 of the connecting pipe 22, a perforated pipe 21 is provided in the static bucket 12a or dynamic bucket 12b, and the fluid holding device 23 is provided on the rotating arm 111 of the centrifugal model experimental apparatus 10. Furthermore, although a regulator 222 is provided in the connecting pipe 22 as a mechanism to adjust the pressurized liquid L flowing in from the fluid holding device 23 to a desired pressure, it is not limited to this. Other pressure adjustment mechanisms may be used as long as they have a similar function, or the pressure may be adjusted by the opening degree of the solenoid valve 223. Also, the pressure adjustment mechanism and the solenoid valve 223 may be omitted.

[0058] In this embodiment, a ground model 30 was used as an example of a model from which fluid is released, but it is not limited to ground. Furthermore, the fluid release mechanism 20 can be mounted on any newly manufactured or modified centrifugal model experimental apparatus 10. [Explanation of Symbols]

[0059] 10. Centrifugal Model Experiment Apparatus 11 Rotating device 111 Rotating Arm 112 Vertical axis 113 Drive mechanism 114 horizontal axis 12 Buckets (storage containers) 12a Static bucket 12b Dynamic Bucket 121 Bottom 122 Vibration Table 20 Fluid release mechanism 21 Perforated pipe 211 Pipe body 212 Spray nozzle 213 Through hole 214 Strainer section 22 connecting pipes 221 Main body of the pipe 222 Regulator (Pressure Adjustment Mechanism) 223 Solenoid valve (on / off valve) 23 Fluid holding device 24. Accumulator (fluid retention device) 241 Main unit 242 Membrane body 25 Separate liquid retention device (fluid retention device) 251 Liquid-filled section 251a Gate valve 252 Gas-filled section 253 Solenoid valve 254 Communication pipe 30 Ground model 31. Foundation Layer 32 Embankment 40 Earthen tank 41 Side panel 42 Bottom plate 50 Installation stand L liquid A Nitrogen gas

Claims

1. A fluid holding device that holds a fluid under pressure, A fluid discharge mechanism comprising a perforated pipe for discharging the fluid supplied from the fluid holding device onto a model.

2. In the fluid discharge mechanism described in claim 1, The fluid holding device is an accumulator, A fluid discharge mechanism characterized in that the fluid is a liquid accumulated in the accumulator.

3. In the fluid discharge mechanism described in claim 1, A fluid discharge mechanism characterized in that an injection nozzle is provided in the perforated pipe.

4. In the fluid discharge mechanism described in claim 1, The system includes a connecting pipe that connects the perforated pipe and the fluid holding device, A fluid discharge mechanism characterized in that the connecting pipe is provided with a pressure adjustment mechanism that adjusts the pressure of the fluid flowing in from the fluid holding device and supplies it to the perforated pipe.

5. In the fluid discharge mechanism described in claim 4, A fluid discharge mechanism characterized by having an on / off valve in the connecting pipe.

6. A centrifugal model experimental apparatus comprising a fluid discharge mechanism according to any one of claims 1 to 5, A rotating device that rotates around a vertical axis, The rotating device is installed in a state that allows it to swing freely around a horizontal axis and includes a storage container for storing a model, The centrifugal model experimental apparatus is characterized in that the fluid discharge mechanism is installed in the storage container.

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