JP2024061706A - Air floatation seismic isolation device and air supply unit for air floatation seismic isolation device - Google Patents

Abstract

[Problem] This air-floating seismic isolation device detects P waves during an earthquake, and supplies compressed air from a high-pressure tank to lift the building, thereby suppressing shaking of the building caused by the S waves of the earthquake. [Solution] This air-floating seismic isolation device detects P waves during an earthquake, and discharges compressed air from a compressed air tank to supply compressed air to a space provided under the building, thereby lifting the building before the S waves of the earthquake arrive, thereby suppressing shaking of the building. This air-floating seismic isolation device is composed of an artificial base, an air-filled chamber for lifting, which is a space above the artificial base into which compressed air is filled, a building foundation, and an air supply unit composed of a compressed air tank, a solenoid valve, and piping that supplies compressed air to the air-filled chamber for lifting. This air-floating seismic isolation device is characterized in that the compressed air tank is a high-pressure compressed air tank that functions as an isothermal pressure vessel, and the air supply unit is further equipped with a flow amplifier and a check valve. [Selected drawing] Figure 3

Description

The present invention relates to an air-floating seismic isolation device and an air supply unit for the air-floating seismic isolation device that are installed in a building, and more specifically, to an air-floating seismic isolation device equipped with an air supply unit that detects P waves during an earthquake and quickly supplies compressed air to the space between the building and the foundation.

Japan is a country prone to earthquakes, and in the Great East Japan Earthquake that occurred on March 11, 2011, damage to houses reached 130,000 buildings that were completely destroyed, 270,000 buildings that were partially destroyed, and 740,000 buildings that were partially damaged. Of the 130,000 buildings that were completely destroyed, about 90% was caused by the tsunami, but about 10,000 buildings were damaged by the earthquake. Since then, earthquakes thought to be aftershocks of the Great East Japan Earthquake have occurred, and it is predicted that three huge earthquakes will occur in the Pacific coastal areas within the next 30 years. In order to prevent damage from earthquakes, many seismic isolation technologies for detached houses have been proposed and implemented in recent years. These are methods that strengthen the pillars, increase the strength of the building, and focus on earthquake resistance to prevent detached houses from collapsing.

Patent Document 1 discloses an invention relating to a rubber plate shock absorbing mechanism and an air floating type seismic isolation device.
The air-floatation seismic isolation device described in this document is an air-floatation seismic isolation device that comprises a lower foundation, an upper foundation placed on the lower foundation, a metal sealing plate whose upper end is airtightly fixed to the upper foundation and whose lower end elastically contacts the lower foundation to form an air pressure chamber, and a pressurized air tank, and is characterized in that when a sensor detects earthquake tremors, it opens a solenoid valve to supply compressed air to the air pressure chamber surrounded by the metal sealing plate to levitate the upper foundation, and the air supply unit is stored above the upper foundation.
This air-floating seismic isolation device is equipped with a rubber plate cushioning mechanism consisting of a ring-shaped high-damping rubber with a central opening, with both the upper and lower surfaces inclined toward the inner or outer circumference, and a protruding shaft with a lid that is inserted into the central opening.

JP 2017-89277 A

This patent document states that the floor area of a building equipped with an air levitation type seismic isolation device is 20 tsubo ( ⁶⁶ m2), the building is lifted to a height of 3 to 5 cm, and the building is lifted in about 2 seconds using 15 to 30 mm piping.
Here, if the inner diameter of the pipe is 30 mm and it takes 2 seconds to reach a floating height of 3 cm, strictly speaking, the characteristics of the compressible fluid must be taken into consideration, as will be described in detail below, but a simple calculation based on the cross-sectional area of the pipe results in a flow velocity of 1,400 m/s, and even if multiple pipes, for example four, are used, the flow velocity will be 350 m/s, which exceeds the speed of sound.
When dealing with air, which is a fluid, there are issues such as the effective cross-sectional area of solenoid valves and piping, the saturation of the mass flow rate when the flow velocity reaches the speed of sound, and adiabatic changes that occur when air is released from a pressure vessel, and there are many challenges to overcome in levitating a building in around two seconds.

The present invention solves the above problems by detecting the P-waves of an earthquake using an earthquake sensor, and then using compressed air to lift the building at a specified lift time to suppress earthquake vibrations. This air-floating seismic isolation device not only reduces damage to buildings, but also minimizes shaking inside the building, preventing the risk of objects falling.
In this air-levitation seismic isolation device, the time it takes for the building to rise is very important. If the epicenter is close, the difference in arrival time between the P-waves and the S-waves becomes short, so it is desirable to raise the building as quickly as possible.
Therefore, in the present invention, in order to shorten the time it takes for a building to rise, a high-pressure compressed air tank with the function of an isothermal pressure vessel is used. In addition, by using a high-pressure compressed air tank, the total volume and installation area of the compressed air tank can be reduced. Furthermore, by using a flow amplifier, the time it takes to rise can be further shortened.

In other words, the present invention is an air-floating seismic isolation device that detects P waves during an earthquake, discharges compressed air from a compressed air tank, supplies compressed air to a space formed under a building, and floats the building for a specified floating time to suppress earthquake swaying, the air-floating seismic isolation device is equipped with an air supply unit that supplies compressed air to the space, the air supply unit being composed of a compressed air tank, an electromagnetic valve, and piping, the compressed air tank is a high-pressure compressed air tank, and the building is floated multiple times in succession in preparation for aftershocks without being filled with compressed air from the high-pressure compressed air tank, and further, the high-pressure compressed air tanks are installed inside the building by arranging multiple high-pressure compressed air tanks side by side and stacking them horizontally and vertically to reduce the installation area, the specified floating time is a time calculated based on an effective cross-sectional area calculated from the inner diameter of the electromagnetic valve and the inner diameter and length of the piping, and is the time from the occurrence of an earthquake when P waves are detected to the arrival of S waves to float the building.

By configuring it in this way, it is possible to shorten the ascent time and reduce the installation area by using a high-pressure compressed air tank (hereinafter referred to as the "high-pressure tank").

The air-floating seismic isolation device of the present invention is further composed of an artificial base installed on the ground, an air-filled chamber for levitation, which is a space above the artificial base that is filled with compressed air, a building base installed above the air-filled chamber for levitation, and a control unit that sends signals to open and close the solenoid valve based on signals from the earthquake sensor and height sensor. The air-filled chamber for levitation is surrounded by the underside of the building base, the upper surface of the artificial base, and multiple metal sealing plates whose upper ends are airtightly fixed to the side of the building base and whose lower ends are elastically bent and come into contact with the upper surface of the artificial base. The high-pressure compressed air tank is filled with bundles of thin wires made of a highly thermally conductive material, and is characterized by having the function of an isothermal pressure vessel.

By configuring it in this way, compressed air can be supplied from the high-pressure tank to the air-filled chamber for lifting located at the bottom of the building, allowing the building to be lifted in a short time after an earthquake occurs. In addition, by making it an isothermal pressure vessel, it is possible to suppress sudden temperature changes when releasing air from the high-pressure tank.

Furthermore, the air supply unit of the present invention further comprises a flow amplifier and a check valve, and the air floating seismic isolation device is further characterized by comprising a compressor that fills a high-pressure compressed air tank with compressed air, and a battery that can operate the compressor, the solenoid valve, and the control unit that drives the solenoid valve in the event of a power outage after an earthquake.
By installing a flow amplifier, the compressed air discharged from the high-pressure tank required for lifting the building can be amplified. In addition, even if there is a power outage after an earthquake, the compressor can be used to fill the high-pressure tank with compressed air, making it possible to reduce the number of high-pressure tanks and shorten the time it takes to lift the building.

Furthermore, the air levitation type seismic isolation device is characterized in that it is provided with a plurality of air supply units connected to the plurality of connection ports in order to shorten the piping length from the air supply unit to the space or the plurality of connection ports of the air filling chamber for levitation, and is provided with a compressor and a battery that fills the high-pressure compressed air tanks of the plurality of air supply units with compressed air.
With this configuration, by using multiple air supply units with short piping, a large amount of air can be supplied in a short period of time, thereby shortening the time it takes for the building to float.

The present invention also provides an air supply unit for an air-floatation seismic isolation device that detects P-waves during an earthquake, discharges compressed air from a compressed air tank, supplies compressed air to a space formed under a building, and floats the building in a predetermined floating time to suppress earthquake tremors, the air supply unit being composed of a compressed air tank, a solenoid valve, a flow amplifier, a check valve, and piping, the compressed air tank being a high-pressure compressed air tank filled with a bundle of thin wires made of a highly thermally conductive material and having a function as an isothermal pressure vessel, the high-pressure compressed air tank is used to continuously float the building multiple times in preparation for aftershocks without filling it with compressed air, and the high-pressure compressed air tanks are installed within the building by arranging multiple high-pressure compressed air tanks side by side and overlapping them horizontally and vertically to reduce the installation area, and the predetermined floating time is a time calculated based on an effective cross-sectional area calculated from the inner diameter of the solenoid valve and the inner diameter and length of the piping, and is the time from the occurrence of an earthquake when P-waves are detected to the arrival of S-waves to float the building.
This air supply unit allows the flow rate to be increased, shortening the ascent time and reducing the number of high-pressure compressed air tanks required.

As described above, according to the present invention, it is possible to detect P waves during an earthquake and supply compressed air from the high-pressure tank in a short time to lift the building and suppress shaking of the building caused by the S waves of the earthquake. In addition, by equipping the high-pressure tank with the function of an isothermal pressure vessel, it is possible to suppress temperature changes inside the high-pressure tank, and furthermore, the number of high-pressure tanks can be reduced by using a flow amplifier.

FIG. 1 is a schematic diagram of an air-floating seismic isolation device before an earthquake occurs. FIG. 1 is a schematic diagram of an air levitation seismic isolation device in operation after an earthquake occurs. FIG. 1 is a schematic diagram of an air supply unit including a high pressure tank, a flow amplifier and a check valve. FIG. 1 is a diagram of a measurement device for measuring the gain of a flow amplifier. FIG. 13 is a diagram showing data on the inlet flow rate versus outlet flow rate of a flow amplifier. FIG. 13 is a diagram showing calculation data of the amplification factor with respect to the inflow flow rate of a flow amplifier. FIG. 13 is a diagram showing measurement data of discharge pressure versus inflow flow rate of a flow amplifier.

An air floating type seismic isolation device according to an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a schematic diagram of an air-floatation seismic isolation device before an earthquake occurs. Fig. 2 is a schematic diagram of the air-floatation seismic isolation device in operation after an earthquake occurs. The difference between Fig. 1 and Fig. 2 is whether compressed air is supplied to the air-filled chamber for floating. In addition, Fig. 1 and Fig. 2 omit the structure of the building.

The air-floating seismic isolation device 100 is composed of an artificial base 1, a building foundation 2 placed on the artificial base 1, a metal seal plate 4, an air supply unit 20, an earthquake sensor 24, a control unit 25, and a height sensor 26. Furthermore, in this embodiment, the metal seal plate 4 is airtightly fixed to the entire periphery of the side of the building foundation 2 with bolts 10, and its lower end elastically contacts the artificial base 1.

The metal sealing plate 4 may divide the building foundation 2 into several sections and surround the periphery of each section. In this way, even if the weight of the building is unbalanced, it can be balanced and floated horizontally. The building 5 is assembled on the building foundation 2. For example, in a three-story detached house in an urban area, if the first floor is a garage and the second and third floors are residences, the air supply unit 20 and other parts may be stored in the garage on the first floor.

In this embodiment, the building 5 is assumed to be an urban residence. For example, the building 5 is a two- or three-story wooden building weighing about 40 tons and having a floor area of 40 square meters (about 12 tsubo). The pressure in the building is about 1000 kgf/ ^m2 , which is about 0.10 atmospheres.

The artificial base 1 is rectangular and can be made of concrete. The artificial base 1 has a smooth surface portion 9 on the upper surface with which the metal sealing plate 4 comes into contact. Even if the artificial base 1 slides due to vibration during an earthquake, the metal sealing plate 4 prevents significant air leakage from the bottom. The smooth surface portion 9 may be the entire upper surface of the artificial base 1, or may have a predetermined width, for example, 60 cm to 120 cm.

The smooth surface portion 9 can be achieved by polishing with an engine-powered rotary trowel. It may be covered with a stainless steel metal plate, or a resin plate may be used. When expressing the smoothness of the smooth surface portion 9 as the maximum height difference between the concaves and convexes, it is preferable that the smoothness is within ±1 mm. It is preferable that the artificial base 1 is higher than the ground to prevent dust, rainwater, etc. from entering.

As shown in FIG. 1, in this embodiment, a metal seal plate 4 is attached to the side of the building foundation 2. The metal seal plate 4 seals the floating air filling chamber 3 (corresponding to the "space" of the present invention) so that air does not leak. The upper end of the metal seal plate 4 is fixed to the building foundation 2 with a bolt 10 or the like, and the lower end is inserted into the notched groove 8. The metal seal plate 4 is bent and elastically biased, and the lower end abuts against the smooth surface portion 9. The metal seal plate 4 is preferably a stainless steel plate in terms of elasticity, strength, and corrosion resistance. For example, the metal seal plate 4 may be 1 to 3 m long, 15 to 25 cm wide, and 0.15 to 0.6 mm thick.

As shown in Fig. 1, an air supply unit 20 is installed on the building foundation 2. A building 5 is constructed on the building foundation 2. The air supply unit 20 is composed of a high-pressure tank 21, a solenoid valve 22, and an air supply pipe (piping) 23. Furthermore, the air floating type seismic isolation device 100 is equipped with an earthquake sensor 24, a control unit 25, and a height sensor 26. Because the air supply unit 20 is installed inside the building foundation 2, the piping 23 does not vibrate during an earthquake, and displacement or damage to the piping 23 can be prevented.
Furthermore, in the case of a two-story house, the air supply unit 20 may be installed under the floor of the building 5. The air supply unit 20 is a unit composed of a 5 L high-pressure tank 21, an electromagnetic valve 22, and piping 23, and if there are two or four high-pressure tanks as described below, each unit can be easily installed under the floor of the building.

Furthermore, flexible pipes are used for water supply and sewerage pipes, etc., as they are connected to the outside of the building. The piping 23 penetrates from the top to the bottom of the building foundation 2 and is connected to the air-filled chamber 3 for flotation. The connection port 6 through which the piping 23 penetrates may be in one place, but is preferably provided in multiple places. The inner diameter of the piping is 40 mm, but is not limited to this inner diameter. Compressed air from the high-pressure tank 21 is sent to the air-filled chamber 3 for flotation between the artificial foundation 1 and the building foundation 2. The building foundation 2 is levitated by the pressure of the compressed air. In other words, the shaking of the artificial foundation 1 is suppressed by the air, thereby providing a seismic isolation effect.

When an earthquake occurs, the earthquake sensor 24 detects the initial tremors (P waves) of the earthquake and sends a signal to the control unit 25. When a predetermined shaking amplitude occurs, the control unit 25 sends an open signal to the solenoid valve 22. As a result, compressed air is supplied to the flotation air filling chamber 3 via the pipe 23 in a short time, and the building foundation 2 is lifted up.
The standard for opening the solenoid valve 22 when the oscillation amplitude (magnitude of the P wave) is equal to or greater than a predetermined amplitude can be set by the control unit 25 .

The control unit 25 sends an open signal to the solenoid valve 22 upon receiving a signal from the earthquake sensor 24, and sends a close signal to the solenoid valve 22 when the height sensor 26 detects a predetermined height. Since a small amount of compressed air leaks from the levitation air filling chamber 3, if the earthquake continues for a long time, the control unit 25 may again send an open signal to the solenoid valve 22 in response to a signal from the height sensor 26, so that compressed air is supplied to the levitation air filling chamber 3. The symbol H shown in Figure 2 is the height of the levitation air filling chamber 3, and in the event of an earthquake, the height rises to 2 cm in this embodiment due to the supply of compressed air. Note that the levitation height is not limited to 2 cm, and can be set by the control unit 25 in response to a signal from the height sensor 26.

When an earthquake is detected, the building foundation 2 rises due to the compressed air supplied to the air-filled chamber 3 for lifting, and in this state the artificial base 1 vibrates from side to side. Even if the artificial base 1 moves from side to side, after the earthquake has subsided, a rubber plate shock absorber or the like may be used to suppress positional deviation between the artificial base 1 and the building foundation 2 so that they are within a specified range of positional relationship.

3 is a schematic diagram of an air supply unit including a high pressure tank, a flow amplifier and a check valve. By using this air supply unit 20, a building can be levitated in a short time even if an earthquake occurs.
The air supply unit 20 of this air levitation type seismic isolation device 100 supplies compressed air at a pressure of 4.5 MPa with a total volume of 100 L, as shown in Figure 3, by connecting 20 high-pressure tanks with a capacity of 5 L in parallel. It is designed to lift a detached house weighing 40 tons and with a floor area of ⁴⁰ m2 in a short period of time. Air flows from the high-pressure tank 21 through a solenoid valve 22 with an inner diameter of 1 inch and a pipe 23 with an inner diameter of 40 mm and a length of 10 m to the building, lifting the building 2 cm in a short period of time.
Incidentally, the setting examples of the building, piping lengths, etc. in this embodiment (hereinafter referred to as "examples") are merely examples, and needless to say, they may be modified in various ways depending on the size of the building.

Here, the term "high pressure" used in the present invention is assumed to mean a pressure with a gauge pressure of 1 MPa or more. In other words, the High Pressure Gas Safety Act (Act No. 204 of 1951) stipulates in its Article 2 (Definition) heading and paragraph 1 that "In this Act, 'high pressure gas' means ... compressed gas with a pressure (gauge pressure) of 1 MPa or more at normal operating temperatures," and this definition of high pressure is used.
Furthermore, when searching the internet for the compressor used in the examples of the present application, it is found that "normal compressors are called 'normal pressure' and high-pressure compressors are called 'high pressure'. Even the highest maximum pressure of normal compressors is often around 1.4 MPa, but the mainstream of high-pressure compressors are around 4.5 MPa," and this is based on the classification of normal pressure and high pressure and their pressure ranges used here.

In the embodiment of the present invention, a 5L high-pressure tank is used. Conventional air levitation seismic isolation devices use six 200L compressed air tanks, so the space required for six compressed air tanks is large. For example, about three tatami mats is required within a building, making it difficult to secure space to install the compressed air tanks. In this embodiment, 20 high-pressure tanks are used, but this can be reduced to 8-10, allowing for a variety of options for the location of the high-pressure tanks, such as a first-floor garage, under the floor of a residence or under the stairs to the second floor, or outside the building, under a wooden deck.

In particular, the present invention is intended to be applied to urban housing (urban housing), and in the embodiment described below, the use of high-pressure tanks allows the volume and weight of each tank to be made smaller and lighter than conventional tanks. For example, as described below, even if 13 high-pressure tanks are used, each tank has an outer diameter of 15 cm, a length of 50 cm, and weighs approximately 6 kg. The effect of using high-pressure tanks is realized by storing them in a wooden or metal rack that can be installed in four tanks x four levels, and by storing the combination equipped with a compressor that fills the high-pressure tanks with air under the stairs to the second floor.

In addition, as for the 5L high-pressure tank, although the filling pressure is high at 4.5MPa, since the volume is only 5L, it does not fall under the category of a second-class pressure vessel, and there is no need to submit any paperwork or other procedures regarding its manufacture, installation, or use.

When compressed air is discharged from a high-pressure tank, the pressure in the high-pressure tank drops suddenly, causing the temperature inside the tank to drop and, in some cases, to drop below freezing, causing the water vapor in the compressed air to freeze. To prevent this, the high-pressure tank functions as an isothermal pressure vessel.
That is, in the high-pressure tank, thin metal wires are formed from a metal material with high thermal conductivity such as copper, aluminum, stainless steel, etc., so as to reduce the volume, and are then packed and housed in a rolled shape so as to increase the contact area with the compressed air in the high-pressure tank. Not limited to metal materials, resins such as polyester can also be used, although their thermal conductivity is inferior to that of metals.
For example, when made of steel wool, the thin metal wire can be constructed with a volume of about 1% of the volume of the high-pressure tank 21, so that the volume of the high-pressure tank 21 itself is not significantly sacrificed.

The high-pressure tank 21 is filled with compressed air that can float multiple times, for example five times, in preparation for possible aftershocks. This air-floating seismic isolation device can reduce damage even in the case of a magnitude 7 earthquake.

Here, the time it takes for the building 5 to float will be considered based on the characteristics of the compressible fluid, i.e., the effective cross-sectional area due to the length and inner diameter of the solenoid valve 22 and piping 23, the volume of the high-pressure tank 21, the flow velocity in the piping 23, and the temperature change when the compressed air is discharged from the high-pressure tank 21.

In the present invention, the floating time calculated as described above is considered to be a specified floating time, but this floating time does not become a fixed value depending on the size of the building 5, i.e., the length and inner diameter of the pipes 23, the volume (number) of the high-pressure tanks, etc., and also on differences in the floor area of each building, etc.
However, the specified rising time needs to be shorter than the time from when the P waves arrive and detect the occurrence of an earthquake until when the S waves arrive.

The time between the arrival of P waves and the arrival of S waves will be considered. The speeds of P waves and S waves vary depending on factors such as the hardness of the earth's crust, and there is a wide range of speed values. In the present invention, a P wave speed of approximately 7 km and an S wave speed of approximately 4 km based on data from the Japan Meteorological Agency are used. Since earthquakes generally occur at depths of around 10 km to 50 km, if we consider a case in which the shortest distance to the epicenter is 10 km directly below a residential building 5, the time between the arrival of P waves and the arrival of S waves will be as short as 1.1 seconds. If the specified floating time is less than this shortest time, building 5 will have completed floating by the time the S waves arrive.

As will be described later, in the present invention, if a given number of pipes are arranged in one building, and a flow amplifier is used, the given floating time can be set to one second.
On the other hand, it is also considered that the speed of S-waves is several hundred meters per second in layers close to the ground surface, and in this case, the time from when the P-waves arrive until when the S-waves arrive may be considered to be about 2 to 3 seconds. Therefore, in the embodiment described later, the predetermined time was set to 2 seconds, taking into consideration the number of pipes, etc.

First, the pressure required for the high-pressure tank 21 is calculated using Boyle's law. The air pressure is calculated from the balance of forces using equation (1). Here, P is the pressure in the air-filled chamber 3 for lifting [Pa], A is the floor area of the building foundation 2 [ ^m2 ], m is the mass of the building [kg], and g is the acceleration of gravity [m/ ^s2 ].

次に、ボイルシャルルの法則を使い、必要な高圧タンクへの充填圧力を求める。Ｖ１は建物を持ち上げるための浮上用空気充填室３の体積［Ｌ］、Ｖ２は高圧タンクの合計体積［Ｌ］、Ｐｔは高圧タンクへの充填圧力［ｋＰａ］、ｎは浮上させる回数［回］である。

Here, Pa is the atmospheric pressure [kPa], and Ps is the air pressure required for lifting [kPa].

Next, using Boyle's law, we calculate the necessary filling pressure for the high-pressure tank. V1 is the volume [L] of the flotation air filling chamber 3 for lifting the building, V2 is the total volume [L] of the high-pressure tank, Pt is the filling pressure [kPa] to the high-pressure tank, and n is the number of times to flotation [times].

で求められる。 Next, the effective cross-sectional areas of the solenoid valve 22 and the pipe 23 are calculated. In the case of the solenoid valve 22, the cross-sectional area is set to 80% of the inner diameter, and the effective cross-sectional area of the pipe 23 is set to S ₁ [mm ² ]. Using the inner diameter d [mm] of the pipe 23, the length L [mm] of the pipe 23, and the friction coefficient λ of the pipe 23,

It can be calculated as follows.

Here, a composite effective cross-sectional area S of the electromagnetic valve 22 and the pipe 23 used in the air supply unit 20 is calculated from the individual effective cross-sectional areas of these.
In general, the composite effective cross-sectional area of a series arrangement is given by formula (5): S is the composite effective cross-sectional area [mm ² ], and Si (i=1 to n) is the effective cross-sectional area of each element.

で求められる。
浮上用空気充填室３に供給する圧縮空気の流量を体積流量Ｑａｎｒとすると、合成有効断面積Ｓより流速μ［ｍ／ｓ］が求まる。

In addition, the composite effective cross-sectional area of the parallel arrangement is

It can be calculated as follows.
If the flow rate of the compressed air supplied to the floating air filling chamber 3 is taken as the volumetric flow rate Qanr, the flow velocity μ [m/s] can be calculated from the combined effective cross-sectional area S.

Finally, the volumetric flow rate at which air is released from the high-pressure tank (gauge pressure P1) through the solenoid valve and piping with a composite effective cross-sectional area S is given by Equation (8), where Qanr is the volumetric flow rate [L/min] through the piping, and P1 is the gauge pressure of the tank [MPa].

Numerical values relating to this embodiment of the air floating type seismic isolation device 100 of the present invention are input into each of the above formulas.
First, the pressure for lifting the building foundation 2 and the building 5 is calculated from the formula (1). In the setting of this embodiment, the mass of the building 5 is 40 tons (4×10 ⁴ kg) and the floor area is 40 m ² , so

よって、Ｐｓは１１０［ｋＰａ］となる。 From equation (1), the pressure P is about 10 kPa. Also, from equation (2), the air pressure Ps required for floating is, since the atmospheric pressure P is 100 kPa,

Therefore, Ps is 110 [kPa].

この結果より、高圧タンク２１の本数２０本およびその高圧タンクの内圧４．５ＭＰａは適切な値である。
ここで、圧縮機２９により高圧タンク２１に圧縮空気の充填が可能とし、停電でも蓄電池（バッテリー）等により圧縮機２９の運転が可能として、持ち上げ回数を１回とすると、

となって、合計２０Ｌ、すなわち高圧タンクが４本あれば、１回建物を上昇させることができる。 The filling pressure of the high-pressure tank 21 is calculated from the formula (3). If the floor area is 40 ^m2 , the floating height is 2 cm, the volume V1 is 0.8 ^m3 , and the number of lifts is 5. If the number of high-pressure tanks is 20 (5 L x 20 = 100 L), then:

From this result, the number of high-pressure tanks 21, 20, and the internal pressure of the high-pressure tanks, 4.5 MPa, are appropriate values.
Here, assuming that the compressor 29 can fill the high-pressure tank 21 with compressed air, that the compressor 29 can be operated using a storage battery or the like even during a power outage, and that the number of lifts is one,

So, a total of 20L, or four high-pressure tanks, is needed to lift a building once.

となる。 Regarding the effective cross-sectional area, if the effective cross-sectional area of the solenoid valve 22 with an inner diameter of 1 inch is ⁴⁰⁰ mm2, the pipe 23 has an inner diameter of 40 mm, and the length including the pipe between the high-pressure tank 21 and the solenoid valve 22 is 10 m, then from equation (4) the effective cross-sectional area of one pipe 23 is ⁵¹³ mm2 (λ = 0.02). If air is supplied to the floating air filling chamber 3 through this pipe, then from equations (5) and (6), the composite effective cross-sectional area S is

It becomes.

であり、１秒間の流量は３．４×１０^３［Ｌ／ｓ］となり、式（７）より流速を計算すると音速を超えている。
この場合、高圧タンク２１からの吐出流量の能力はあっても配管２３の有効断面積とその流速を考慮する必要がある。
すなわち、高圧にすることで、圧力に応じて流量が増加すると思われるが、流速は音速を超えないことや、圧縮空気の放出時の温度変化、また電磁弁２２に接続される配管２３の本数やその長さおよび内径等による有効断面積を検討する必要がある。 Verify how many seconds it takes to float the tank using the effective cross-sectional area of the solenoid valve 22 and the pipe 23. Since the gauge pressure of the high-pressure tank is 4.4 [MPa], calculate the flow rate of the pipe 23 from equation (8):

The flow rate per second is 3.4×10 ³ [L/s], and the flow velocity calculated from equation (7) exceeds the speed of sound.
In this case, even if the high-pressure tank 21 has a sufficient discharge flow rate, it is necessary to take into consideration the effective cross-sectional area of the pipe 23 and its flow rate.
In other words, it is thought that increasing the pressure will increase the flow rate in proportion to the pressure, but it is necessary to consider that the flow velocity does not exceed the speed of sound, the temperature change when the compressed air is released, and the number of pipes 23 connected to the solenoid valve 22, their lengths, their inner diameters, and other factors that determine the effective cross-sectional area.

In reality, the air flow velocity in the pipe 23 does not exceed the speed of sound, so consideration must be given to making the flow velocity equal to or lower than the speed of sound.
For example, with the above settings, the effective cross-sectional area of one pipe is ⁵¹³ mm2, and the maximum flow velocity at that time is 330 m/s. The volumetric flow rate is calculated by multiplying the effective cross-sectional area by the flow velocity, so it is 0.17 ^m3 /s per pipe, and 0.51 ^m3 /s for three pipes.
In this case, the floating air filling chamber 3 becomes 110 kPa with 0.8 ^m3 during floating, and taking the pressure into consideration, the volumetric flow rate becomes 0.88 ^m3 , so the floating time becomes 1.7 seconds. In order to achieve a floating time of 1 second, five or more pipes 23 should be used. It can also be achieved by using a flow amplifier, as described later.

Here, we consider adding a flow amplifier 27 to the air supply unit 20 to shorten the time it takes for the building to rise when an earthquake occurs and to reduce the number of high-pressure tanks.
Referring again to Figure 3, the flow amplifier 27 is a device in which the compressed air entering from the amplifier main body inlet passes through a narrow section, increasing the flow rate, and the high-speed air that enters the main body flows along the inner wall surface, creating a low-pressure state and drawing in a large amount of secondary air. At the outlet, the air volume can be amplified by several times or more, and the air volume can be further amplified by drawing in the air near the outlet.
In the present invention, a check valve 28 is added to the flow amplifier 27. In the floating air chamber 3, pressure is generated by the weight of the building 5 when in operation. It is necessary to prevent the backflow of the compressed air in the floating air chamber 3 by the check valve 28.

The amplification factor of the flow amplifier 27 will now be described.
4 is a diagram of a measuring device that measures the amplification factor of a flow amplifier. The flow measurement device is composed of a regulator, a flow meter, a flow amplifier 27, a pipe (piping), and a pressure sensor from the upstream side, and the flow rate flowing through the measuring device and the pressure at the discharge port are measured by a control device (a PC in the measuring device).
In this measurement device, the inflow flow rate was adjusted with a regulator, and the inflow flow rate and the pressure at the outlet were measured. The inflow flow rates were set to 30, 60, 90, and 120 L/min (anr), and resistances were attached to the inlet and/or outlet of the flow amplifier to suppress the flow rate.

5 and 6, maximum entrainment is when the entrainment effect is maximized and no resistance to limit flow is attached to either the inlet or outlet of the flow amplifier, and minimum entrainment is when the entrainment effect is minimized and a resistance to limit the entrainment flow is provided at the inlet of the flow amplifier but not at the outlet.
The measurement results of the two settings were compared to consider the effect of entrainment. In addition, the measurement with resistance only at the discharge port was performed to measure the maximum pressure value on the discharge side shown in Figure 7.

FIG. 5 is a graph showing data on the inlet flow rate versus outlet flow rate of a flow amplifier.
5, the horizontal axis represents the inflow flow rate and the vertical axis represents the outflow flow rate. The inflow flow rate was set at four different values.
The discharge flow rate values in Figure 5 confirm that the entrainment effect significantly increases the flow rate. When the inflow rate is low, the difference in discharge flow rate due to the entrainment effect is relatively small, but as the flow rate increases, the difference becomes larger. In addition, at each setting, the discharge flow rate increases almost in proportion to the inflow rate.
The inflow flow rate is measured by a flow measuring device, but the discharge flow rate is calculated by determining the flow velocity from the pressure value (dynamic pressure) at the discharge port and multiplying this by the effective cross-sectional area.

FIG. 6 is a diagram showing calculation data of the amplification factor with respect to the inflow flow rate of the flow amplifier.
6, the horizontal axis represents the inflow flow rate converted into the Reynolds number, and the vertical axis represents the amplification factor, which is calculated by the discharge flow rate/inflow flow rate.
Here, the Reynolds number Re is calculated from the density ρ (1.185 kg/m ³ ), the volumetric flow rate Q (L/min), the inner diameter d (m) of the pipe, and the viscosity coefficient μ (1.8×10 ⁻⁵ ) according to formula (10).

As shown in Figure 6, the amplification factor also differs depending on the entrainment effect. When the entrainment effect is at its maximum, the amplification factor is approximately 8 times. When the entrainment effect is at its minimum, the amplification factor is approximately 2 times. In addition, the amplification factor for each setting gradually decreases as the inflow rate increases.
The most common inflow rate measured is 120 L/min (anr), but in practice the inflow rate is larger as in this embodiment. If the inflow rate increases, the inner diameter is increased accordingly and the Reynolds number remains unchanged, a similar amplification rate can be expected.

FIG. 7 is a diagram showing measurement data of the discharge pressure versus the inflow flow rate of the flow amplifier.
7, the horizontal axis represents the inflow flow rate, and the vertical axis represents the discharge pressure. In this case, the flow rate was limited by resistance only at the discharge port.
The discharge pressure increases in proportion to the square of the inflow rate as the inflow rate increases. The discharge pressure at an inflow rate of 120 L/min (anr) obtained this time was 90 Pa.
From this result, the discharge pressure can be approximated by a quadratic expression of the inflow flow rate, and if the pressure required to lift the building 5 is 12 kPa, the inflow flow rate will be 1533 L/min (anr). If the inflow flow rate is greater than this value, the pressure required to lift the building 5 can be maintained.

The reason why the building is raised five times is so that the building can be raised in the same way even if aftershocks occur following the main earthquake, and the necessary number of high-pressure tanks capable of supplying compressed air five times are provided. Five times' worth of compressed air is stored in the high-pressure tank 21 in case the compressor 29 cannot operate due to a power outage after the earthquake.

In addition, since there may be a power outage after an earthquake, a battery (storage battery) may be provided to operate the compressor 29. Providing a battery makes it possible to fill the high-pressure tank with air even during a power outage, eliminating the need to store five times' worth of compressed air and allowing the number of ascents to be reduced to less than five.
For example, if it is sufficient to store enough air for one ascent, it is possible to reduce the number of high-pressure tanks 21. In this case, the number of 5-L high-pressure tanks 21 can be reduced from 20 to 4.
The battery (storage battery) may be charged from a commercial power source, or may be rechargeable from a power generation device such as a solar cell. In either case, it is sufficient to be able to fill the battery with compressed air so that the building can be lifted five times in the event of a power outage after an earthquake.

In this embodiment, the air supply unit 20 is described as being configured as a single set including the compressor 29, and supplies compressed air through three pipes. However, the air supply unit 20, which is configured as a single set (unit) including the high-pressure tank 21, the solenoid valve 22, the flow amplifier 27, the check valve 27 and the pipes 23, may be configured to have a plurality of air supply units 20.
In this case, the length of the piping 23 from each air supply unit 20 to the multiple connection ports 6 of the floating air filling chamber 3 can be shortened, thereby increasing the effective cross-sectional area of the piping discussed above and increasing the amount of air supplied per unit.

In other words, the effective cross-sectional area of one pipe with an inner diameter of 40 mm was calculated above for a length of 10 m, but in a configuration with multiple air supply units 20, for example, if the length of the pipe is 1 m and it can be connected to each connection port 6 of the floating air filling chamber 3, the effective cross-sectional area will be 1026 ^mm2 from equation (4), and the maximum flow rate that can be supplied per unit will be 0.34 ^m3 /s.
In order to lift a 40 ^ton building with a floor area of 40 m2 by 2 cm as set above, a configuration of three units (0.88 ^m3 ÷ 0.34 ^m3 ≈ 2.6) will allow the building 5 to be lifted in one second.
In this case, assuming that the compressor 29 operates in the event of a power outage, four high-pressure tanks 21 are sufficient for one unit of compressed air to lift the building at least once, and if a flow amplifier 27 is further provided, the configuration can consist of only one high-pressure tank.

Furthermore, the number of air supply units 20 may be increased to further shorten the time it takes for the building 5 to float. In this case, the compressor 29 and the battery are common to all the air supply units 20, and supply compressed air to the high-pressure tanks 21 of all the air supply units 20 connected to the compressor 29 via the piping 23.
Furthermore, the earthquake sensor 24 and the control unit 25 are not necessary for each air supply unit 20 , and it is sufficient if the control unit 25 transmits a signal to the solenoid valves 22 of all the air supply units 20 .

In conventional technology, the basis for the time it takes for a building to float was not clear, but in this invention, an analysis was conducted based on the properties of compressible fluid, and by using a high-pressure tank 21 that functions as an isothermal pressure vessel and by providing multiple air supply units 20, it became possible to float a building within one second. Furthermore, by using a flow amplifier 27, it is possible to reduce the number of high-pressure tanks.

As examples of the air levitation type seismic isolation device using the high-pressure tank of the present invention, two model houses have been completed in Kawasaki City, Kanagawa Prefecture. The buildings are two stories tall, with the first and second floors having roughly the same floor area and a roof on top of the cuboid-shaped building. The floor area of the first floor is ⁴⁰ m2, and it is equipped with 13 high-pressure tanks and a compressor. Although the number of tanks is less than 20, the number of consecutive floats is set to three, and the number of floats is compensated for by filling the high-pressure tanks with compressed air using the compressor.
Four high-pressure tanks are arranged side by side on a wooden rack, stacked vertically in four tiers, and installed together with a compressor under the stairs leading to the second floor. This makes it possible to lift the building in about two seconds.

Reference Signs List 1: artificial foundation, 2: building foundation, 3: air-filled chamber for flotation, 4: metal sealing plate, 5: building, 6: connection port, 8: cutout portion, 9: smooth surface portion, 10: bolt, 20: air supply unit, 21: high-pressure tank, 22: solenoid valve, 23: air supply pipe (piping), 24: earthquake sensor, 25: control unit, 26: height sensor, 27: flow amplifier, 28: check valve, 29: compressor.

That is, the present invention is an air-floatation seismic isolation device that detects P waves when an earthquake occurs, discharges compressed air from a compressed air tank, supplies compressed air to a space formed under a building, and floats the building for a predetermined floating time, thereby suppressing earthquake tremors . The air-floatation seismic isolation device is composed of an artificial base installed on the ground, an air-filled chamber for floating which is a space above the artificial base into which compressed air is filled, a building base installed above the air-filled chamber for floating, and a control unit that sends out opening and closing signals for an electromagnetic valve in response to signals from an earthquake sensor and a height sensor, and the air-filled chamber for floating is surrounded by the underside of the building base, the upper surface of the artificial base, and a plurality of metal sealing plates whose upper ends are airtightly fixed to the side of the building base and whose lower ends are elastically bent and come into contact with the upper surface of the artificial base, and the air-floatation seismic isolation device further comprises an air supply unit that supplies compressed air to the space, and the air supply unit comprises a compressed air tank the compressed air tank is a high-pressure compressed air tank having a capacity for compressed air to continuously levitate a building multiple times in preparation for aftershocks without having to refill it with compressed air in between ; when compressed air is discharged from the high-pressure compressed air tank, the pressure inside the high-pressure compressed air tank drops suddenly and the temperature inside the high-pressure compressed air tank drops, so the high-pressure compressed air tank is filled with bundles of thin wires made of a highly thermally conductive material so that it functions as an isothermal pressure vessel; the high-pressure compressed air tank is installed inside the building by arranging multiple high-pressure compressed air tanks side by side and overlapping them horizontally and vertically to reduce the installation area; the specified levitation time is a time calculated based on an effective cross-sectional area calculated from the inner diameter of the solenoid valve and the inner diameter and length of the piping, and is the time from the occurrence of an earthquake when P waves are detected to the arrival of S waves.

With this configuration, by using a high-pressure compressed air tank (hereinafter referred to as "high-pressure tank"), it is possible to shorten the ascent time and reduce the installation area. In addition, since it is a high-pressure compressed air tank, the high-pressure tank is made into an isothermal pressure vessel, which makes it possible to suppress a sudden temperature change when the compressed air is released from the high-pressure tank.

The present invention also relates to an air supply unit for supplying compressed air to a space, which is provided in an air flotation type seismic isolation device that detects P waves when an earthquake occurs, discharges compressed air from a compressed air tank, supplies compressed air to a space formed under a building, and lifts the building in a predetermined lift time to suppress earthquake swaying, the air supply unit being composed of a compressed air tank, a solenoid valve, a flow amplifier, a check valve and piping, the compressed air tank being a high-pressure compressed air tank, and when compressed air is discharged from the high-pressure compressed air tank, the pressure in the high-pressure compressed air tank drops suddenly and the temperature in the high-pressure compressed air tank drops, so that the high-pressure compressed air tank This air supply unit for an air levitation type seismic isolation device is characterized in that it has the function of an isothermal pressure vessel, with a bundle of thin wires made of a highly thermally conductive material filled inside, and has a compressed air capacity that can continuously levitate the building multiple times in preparation for aftershocks without the need to refill with compressed air in between , and further, the high-pressure compressed air tanks are installed inside the building by arranging multiple high-pressure compressed air tanks side by side and stacking them horizontally and vertically to reduce the installation area, and the specified levitation time is calculated based on the effective cross-sectional area calculated from the inner diameter of the solenoid valve and the inner diameter and length of the piping, and is the time from the occurrence of an earthquake when P waves are detected to the arrival of S waves.
This air supply unit can increase the flow rate, shorten the ascent time, and reduce the number of high-pressure compressed air tanks. Furthermore, by making the high-pressure tank of the air supply unit an isothermal pressure vessel, it is possible to suppress sudden temperature changes when releasing air from the high-pressure tank.

Claims (5)

An air-floating seismic isolation device that detects P waves during an earthquake, discharges compressed air from a compressed air tank, supplies compressed air to a space formed under a building, and floats the building for a predetermined floating time to suppress earthquake shaking,
The air floating type seismic isolation device includes an air supply unit for supplying compressed air to the space, the air supply unit being composed of the compressed air tank, an electromagnetic valve, and piping;
The compressed air tank is a high-pressure compressed air tank, and the building is continuously raised multiple times in preparation for aftershocks without being filled with compressed air by the high-pressure compressed air tank, and the high-pressure compressed air tank is installed in the building by arranging multiple high-pressure compressed air tanks side by side and stacking them in the horizontal and vertical directions to reduce the installation area;
The specified floating time is a time calculated based on an effective cross-sectional area calculated from the inner diameter of the solenoid valve and the inner diameter and length of the piping, and is an air-floating seismic isolation device characterized in that it is the time from the occurrence of an earthquake when P waves are detected to the arrival of S waves to floating the building. The air floating type seismic isolation device according to claim 1,
The air-floating seismic isolation device further includes an artificial base installed on the ground;
A floating air filling chamber, which is the space above the artificial base that is filled with compressed air;
A building foundation provided on the air-filled chamber for floating;
A control unit that transmits an opening/closing signal for the solenoid valve based on signals from the earthquake sensor and the height sensor;
The air-filled chamber for floating is surrounded by the underside of the building foundation, the upper surface of the artificial base, and a plurality of metal seal plates whose upper ends are airtightly fixed to the side of the building foundation and whose lower ends are elastically bent to come into contact with the upper surface of the artificial base;
An air-floating seismic isolation device characterized in that the high-pressure compressed air tank is filled with bundles of thin wires made of a highly thermally conductive material, thereby functioning as an isothermal pressure vessel. The air floating type seismic isolation device according to claim 1 or 2,
The air supply unit further comprises a flow amplifier and a check valve;
The air-floatation seismic isolation device is further characterized in that it is equipped with a compressor that fills the high-pressure compressed air tank with compressed air, and a battery that can operate the compressor, the solenoid valve, and the control unit that drives the solenoid valve in the event of a power outage after an earthquake. The air floating type seismic isolation device according to claim 3,
The air-floatation seismic isolation device is characterized in that it has a plurality of air supply units connected to the plurality of connection ports in order to shorten the piping length from the air supply unit to the space or the plurality of connection ports of the flotation air filling chamber, and is provided with the compressor and the battery that fill the high-pressure compressed air tanks of the plurality of air supply units with compressed air. An air supply unit that supplies compressed air to a space formed under a building by detecting P waves at the time of an earthquake and discharging compressed air from a compressed air tank to supply compressed air to the space, and that is provided in an air levitation type seismic isolation device that lifts the building for a predetermined lift time to suppress earthquake shaking,
the air supply unit is composed of the compressed air tank, a solenoid valve, a flow amplifier, a check valve and piping;
The compressed air tank is a high-pressure compressed air tank, and is filled with a bundle of thin wires made of a material with high thermal conductivity to function as an isothermal pressure vessel, and the building is continuously raised multiple times in preparation for aftershocks without being filled with compressed air by the high-pressure compressed air tank, and the high-pressure compressed air tank is installed within the building by arranging multiple high-pressure compressed air tanks side by side and stacking them horizontally and vertically to reduce the installation area,
The air supply unit of an air-floating seismic isolation device, characterized in that the specified floating time is a time calculated based on an effective cross-sectional area calculated from the inner diameter of the solenoid valve and the inner diameter and length of the piping, and is the time it takes to float the building from the time of the occurrence of an earthquake when P waves are detected before S waves arrive.

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