JP3251927B2 - Prevention of liquefaction during ground earthquake by infiltration of dissolved air into the ground - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing liquefaction of a ground during an earthquake.

[0002]

2. Description of the Related Art Soil liquefaction is a peculiar phenomenon that occurs when a loose sandy ground having little or no cohesion due to groundwater is violently shaken by an earthquake. It is a common phenomenon that, when a container loosely filled with sand is shaken violently, the volume of the interparticle void space of the sand in the container is reduced and the sand is shaken to reduce the volume. A similar phenomenon occurs when a dry, loose sand ground is shaken violently by an earthquake, causing the ground to sink due to the reduced void volume of the sand. However, if the dry loose sand ground is shaken, it will not cause any serious damage except for some settlement.

[0003] However, when a loose sandy ground saturated with groundwater or weak in adhesiveness is shaken violently by an earthquake, even if the void volume in the ground is reduced, the void volume is filled with groundwater. The pore volume is reduced due to the force that reduces the pore volume, causing an excessively high excess pore water pressure in the water in the pores, and the contact pressure between the particles that was effectively acting due to gravity is almost zero. , And it becomes as if the soil particles are floating in the groundwater. This state of the ground is called liquefaction.
The liquefied ground takes on the properties of a fluid, loses its resistance to forces acting from the outside, light objects having a lower specific gravity than the ground float up from the ground, and heavy objects having a higher specific gravity than the ground sink into the ground. The liquefied ground gradually flows to the lower side even on a slightly inclined surface that looks almost flat. The fluid pressure of the liquefied ground itself is often not large enough to destroy the structure, but the unliquefied solid ground on the groundwater surface on the flowing liquefied ground also moves with the liquefied ground, The enormous pressure exerted by the moving solid ground on the structure foundation can cause the structure to collapse.

[0004] The conditions of the soil that is liable to cause liquefaction include:
A 50% particle size D50 of 0.074 to 2.0 mm and a load of 2 kgf / cm ² or less were mentioned. However, in the Great Hanshin-Awaji Earthquake, liquefaction occurred on the gravel ground with a D50 of 2.0 mm or more. .

[0005] As a measure against the conventional liquefaction,
Improve the ground to prevent liquefaction. A method of designing a structure so that even if liquefaction occurs does not cause fatal damage to the structure has been considered.

Among the measures for preventing liquefaction by improving the properties of the ground, A.I. B. density increasing method, Consolidation method, C.I. D. Replacement method (improvement of soil quality) There is a method of reducing the degree of saturation.

[0007] The present invention relates to the above-mentioned D.I. It belongs to a method for reducing the degree of saturation and improves the disadvantages of the conventional method for reducing the degree of saturation.

As a conventional method for lowering the degree of saturation, a deep well method and a method for lowering the groundwater level by using a drainage tunnel have been considered.

The deep well method is a method in which groundwater is pumped by a deepwell to lower the groundwater level. This method is considered to be impractical in urban areas because the impact of land subsidence due to a drop in groundwater level is significant.

The drainage tunnel method is a method in which groundwater flows into a porous tunnel installed deep underground, and groundwater is pumped from the tunnel to lower the groundwater level.
This method is also considered to be impractical in urban areas because the impact of ground subsidence due to a drop in groundwater level is significant, as is the case with the deep well method.

[0011]

The conventional method of lowering the degree of saturation (groundwater level) as a countermeasure against liquefaction has a problem that land subsidence occurs and that it is necessary to consider the subsidence of the structure. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a method for preventing liquefaction of a ground during an earthquake by causing dissolved water to penetrate into the ground without causing land subsidence. The air-dissolved water referred to here is, for example, tap water in which the air created by spraying the tap water 20 into the air in a spray form by the aeration apparatus 20a shown in FIG. 1 is dissolved in a saturated state or a supersaturated state.

[0012]

In order to achieve the above object,
Therefore, the air-dissolved water according to claim 1 of the present invention permeates underground.
The liquefaction prevention method of the ground by the earthquake
Is air-dissolved air containing ultra-fine bubbles in the ground with weak adhesion
Continue to infiltrate water to prevent microbubbles from entering the ground
In order to create an enclosure, an impermeable
A perforated tube is provided in a blind groove covering the upper surface with a
Air-dissolved water containing ultra-fine bubbles flows into the perforated tube,
Underground water flow through the perforated pipe in the blind ditch at the downstream end.
Water that contains microbubbles that have penetrated
Do not allow water to flow down to the nearest drain or sewer.
And the embankment or seawall surrounding the zero meter area
Saturation of groundwater in the ground within the range of microbubbles in the foundation ground
Liquefaction by reducing to a level that does not cause liquefaction during an earthquake
It is characterized by preventing.

Further, in the method for preventing liquefaction of the ground during an earthquake by infiltrating air-dissolved water into the ground according to the second aspect of the present invention, the micro-sized ultrafine
In order to generate air bubbles in the dissolved water, ceramics etc.
Ultra-fine filter layer with ultra-fine filtration layer like porous stone
Generated by flowing compressed air through a fine filtration device
The water mixed with the generated ultrafine bubbles is
The upper surface provided at the upstream end of the existing steady groundwater flow is impervious
Flow into a perforated tube in a blind groove covered with a conductive coating.
Features.

According to the third aspect of the present invention, there is provided a method for preventing liquefaction of ground during an earthquake by infiltrating air-dissolved water into the ground.
When infiltrating water into the ground, the height of the bottom of the water tank is moderate
Store tap water in a water tank whose height is almost the same as the sea level.
The water stored in the reservoir is transferred to the upstream end of the steady groundwater flow.
In the process of flowing into the porous tube provided in the
Ultra-fine generated through ultra-fine filtration device such as tone
Tap water mixed with fine air bubbles in the blind groove provided at the upstream end
By infiltrating into the ground through borehole pipes, groundwater
It is characterized in that micro bubbles are generated therein.

Further, in the method for preventing liquefaction of the ground during an earthquake by infiltrating the dissolved water of the air into the ground according to the fourth aspect , the air is dissolved in the inventions of the first, second and third aspects.
When penetrating tap water into the ground, store tap water in a water tank.
To the water stored in the water tank through an ultra-fine filtration device.
The water mixed with the generated ultrafine bubbles is transferred to the upstream end of the groundwater flow.
Through the perforated pipe in the blind groove provided in
Range of microbubbles mixed with the ultrafine bubbles as nuclei
The groundwater saturation of the surrounding ground should not be liquefied during the earthquake.
To prevent liquefaction by lowering
You.

Further, in the method for preventing liquefaction of the ground during an earthquake by infiltrating the dissolved water of air into the ground according to claim 5, the invention according to claims 1, 2, 3 and 4,
When penetrating dissolved tap water into the ground, store the tap water.
When the reservoir is full, the perforated tube in the blind groove
When the water faucet at the water tank drain opening that opens inside automatically opens at a certain time
During operation, ultra-fine bubbles generated by ultra-fine filtration device are mixed
The tap water to be supplied to the hole in the blind groove provided at the upstream end of the groundwater flow.
To penetrate the ground through pipes
Groundwater saturation to the point where liquefaction does not occur during an earthquake
It is characterized by lowering to prevent liquefaction.

Further, in the method for preventing liquefaction of the ground during an earthquake by infiltrating air-dissolved water into the ground according to claim 6, the invention according to claims 1, 2, 3, 4 and 5 is provided.
And a standing pipe provided with a control valve having a water discharge function in the perforated pipe 17
To the control valve 91 having a water discharging function.
The water pressure in the perforated pipe 17 is
It is characterized in that it does not become higher.

Further, in the method for preventing liquefaction of the ground during an earthquake by infiltrating the dissolved water of air into the ground according to claim 7, the invention according to claims 1, 2 , 3, 4, 5 and 6 is applied.
When water is supplied to the perforated pipe 17, the water inside the perforated pipe 17
Prevent pressure from becoming too high compared to surrounding groundwater pressure
For this purpose, a water supply control valve 83
A water supply amount control device provided with a water supply amount is provided.

[0019] According to the present invention, the adhesive strength is weak in the ground which the adhesive strength is weak soil during or steady groundwater flow, to penetrate the saturated or supersaturated air dissolved water was mixed ultrafine bubbles water Thus, a range in which microbubbles are mixed in the ground can be created, and the degree of saturation of groundwater in the ground within the range in which microbubbles are mixed can be reduced to a level at which liquefaction does not occur during an earthquake, thereby preventing liquefaction.

[0020]

[Place where the present invention is applied]

The place where the present invention is applied is a ground where there is a steady groundwater flow, which is a dike surrounding the zero meter area and its foundation ground, a foundation ground of a tide barrier sheet pile wall or a foundation ground of a gravity type revetment wall, For example, as shown in the embodiment of FIGS. 1 and 3, the embankment 2 around the zero meter area 1 (area lower than the middle sea level), the foundation ground 4 of the seawall 3 and the riverside 5 Embankment 2 or seawall 3
This is where there is a steady groundwater flow 7 going inward. In the embankment 2 in the zero meter area 1, the seepage water 8 constantly flows through the ground from the riverside 5 to the inside 6 of the embankment.
Then, it is assumed that there is provided a drainage channel 10 that collectively causes the permeated water 8 to flow down to the foreside 9 of the embankment and guides the water to the pump station. Further, the embankment slope 11 is often covered with a slope protection work 12 such as an impermeable covering 13 (an impermeable covering 13 in Kiso Mikawa). Zero meter area 1 Embankment 2
If an earthquake breaks due to liquefaction of the foundation ground 4 or the embankment body 14 during an earthquake, the river water 15 may flood into the zero meter area 1 inside the embankment 6 and cause disastrous damage to the zero meter area 1.

[0021] The present invention zero meter area 1 around the embankment 2
The case where the present invention is applied will be described based on the schematic diagram shown in FIG. A water storage tank 24 is installed at a middle position in the embankment 14, and the installation level of the water storage tank 24 is such that the height of the bottom surface of the water storage tank 24 (substantially the level of the outlet to the water supply pipe 55) is equal to the medium sea level ±.
The height is almost equal to 0.0 m. In this way, the water pressure inside and outside the perforated pipe can be balanced by the operation of the water supply control valve 83 shown in FIG. In addition, the filter material 16a made of crushed stones, for example, finely and coarsely mixed, is filled in the blind groove 16 at the outer end of the stone pile 58 on the upstream end side,
The perforated pipe 17 is disposed so as to be embedded therein. In the perforated pipe 17, an outlet of an air supply pipe 27 having an outer diameter smaller than the inner diameter of the perforated pipe 17 is concentrically arranged. The inlet of the ultrafine filtration device 56 having an outer diameter smaller than the inner diameter of the perforated tube 17 is connected thereto, and the ultrafine filtration device 56 is disposed concentrically supported by the air supply pipe 27, The outlet at the other end of the ultrafine filtration device 56 is open to the porous tube 17. The lower outlet of the water storage tank 24 and the inlet opening at an intermediate portion of the perforated pipe 17 arranged in the blind groove 16 are connected by a water pipe 55 and supplied by a compressed air supply device 57 such as a compressor. The compressed air 28 is passed through the compressed air supply device 57 and the air supply pipe 27 connected to the ultrafine filtration device 56, and the ultrafine filtration device 5 having the ultrafine filtration layer 56a made of ceramics or the like.
The outlet of the ultrafine filtration device 56 is concentrically disposed in the perforated pipe 17 near the outlet of the water pipe 55 which is opened at an intermediate portion of the perforated pipe 17.

The compressed air supplied by the compressed air supply pipe 27 is passed through the ultrafine filtration device 56 to generate micron-sized ultrafine bubbles e as shown in FIG. 1B. As a result, air-dissolved water containing ultra-fine bubbles is generated by being mixed with the water sent from the water-supply pipe 55, and the air-dissolved water containing the ultra-fine bubbles is discharged downward from the porous tube 17 made of resin. Then, the air-dissolved water containing the released ultrafine bubbles passes through the masonry pile 58 or the submarine ground 59 through the filter material 16a made of crushed stone finely and appropriately mixed in the blind groove 16, and the permeation path 26 or When the air-dissolved water containing ultra-fine bubbles together with the groundwater flow 7 continues to flow into and penetrate into the foundation ground 4 composed of the embankment body 14 and sandy soil, etc., the air-dissolved water containing ultra-fine bubbles from the air-dissolved water decreases with the water pressure. The microbubbles formed by the elution of the dissolved air with the ultrafine bubbles in the nuclei are formed, and the microbubbles continue to be generated in the embankment 14 between the barrier walls 25 and the foundation ground 4, so that the degree of saturation of the groundwater in that portion is reduced. As a result, the degree of saturation of the groundwater in the embankment body 14 and the foundation ground 14 can be reduced. Water tank 2 as described above
4, the equipment such as the water pipe 55, the compressed air supply device 57, and the perforated pipe 17 is, for example, 50 m to 100 m in the longitudinal direction of the embankment 2.
It is preferable to set them appropriately at m intervals. If the ultra-fine bubbles e continue to be mixed in the air-dissolved water for several tens of days until they reach the downstream end perforated pipe 17a, a sufficient number of micro-bubbles will be formed in the permeated water. There is no need to mix them. Usually, water is supplied from one water storage tank 24 to one porous tube 17. The installation interval of the water supply tank 24 is determined by the scale of the embankment, equipment such as a water gate attached to the embankment other than the equipment for carrying out the present invention, the soil quality of the embankment body 14 and the foundation ground. Preferably, the body 14 is installed at an interval of 50 m to 100 m in the longitudinal direction. The water storage tank 24 is placed near the center of the length of one perforated pipe 17 determined by the installation interval in the embodiment, and water is supplied from one water storage tank 24 to one perforated pipe 17. In addition, the air supply pipe 27 and the ultra-fine filtration device 56 provided at the tip thereof are
It is preferable to provide it in the vicinity of a water supply outlet to which the water supply pipe 55 is attached.

The permeated water that has passed through the lower part of the cut-off wall 25 on the inner side of the levee is collected in the blind groove 16a located adjacent to the inner side of the levee 9 on the downstream side of the levee 9 as described above, and is perforated by the perforated pipe 17a.
And drained from the culvert 10. In the case of this embodiment, the water supplied to the water storage tank 24 is tap water 2
This shows a mode using 0. Thus tap water 20
When water is used, water having an appropriate pressure is supplied to the perforated pipe 17 by storing it in the water storage tank 24 and discharging it intermittently to the water supply pipe 55.

[0024] As described above, FIG. 1 (a), the air dissolved water is flowed penetrate into the foundation ground 4 consisting of the dam body 14 and sandy soil or the like by equipment such as (b), the saturation of the ground water If the degree is reduced to a level that does not cause liquefaction of the ground during an earthquake, liquefaction of the levee 2 and its foundation ground 4 during an earthquake can be prevented without impairing the function of the levee 2,
Therefore, it is possible to prevent a breach due to liquefaction of the bank body 14 and the foundation ground 4 beforehand.

[0025] Next, with reference to the left-hand portion of FIG. 2, illustrating the hydraulic control device 93 for controlling the water pressure in the porous tube 17 so as not to become higher than the pressure outside the perforated pipe 17. Since the above-mentioned zero meter area is in contact with the tidal river and the sea area in the seaside city, and the external water surface 15a rises and falls due to ebb and flow, the groundwater pressure in the blind groove 16 outside the perforated pipe 17 rises and falls. On the other hand, the water pressure in the perforated pipe 17 is
It rises and falls according to the water level in 4 above and below. Ideally, the water pressure inside and outside the perforated pipe 17 is balanced, and the permeate flow of the dissolved air produced from the tap water 20 flowing out of the perforated pipe 17 is changed to the river water 15.
It is preferable that the entire amount of the permeated flow of the dissolved air produced from the tap water 20 flow toward the embankment 14 and the ground inside the embankment 6 without wastefully flowing into the external water such as. To this end, as shown in the left part of FIG. 2, the base end of the standpipe 92 is connected to the perforated pipe 17, the upper end of the standpipe 92 is opened above the river 15, and rises from the perforated pipe 17. When the water level in the vertical pipe 90 becomes higher than the external water surface 15a, the water is discharged from the discharge port 95 of the control valve 91 provided in the intermediate portion of the vertical pipe 92 until the water level in the vertical pipe 92 becomes equal to the external water level 15a. When the water level in the vertical pipe 92 is lower than the external water surface 15a, a vertical pipe 92 having a control valve 91 for closing the control valve 91 to prevent the external water 15b from flowing into the vertical pipe 92 is provided. The water pressure in the perforated pipe 17 is not to be higher than the underground water pressure around the perforated pipe 17. When the standing pipe 92 provided with the control valve 91 is provided as described above, when the water pressure in the perforated pipe 17 is lower than the underground water pressure around the perforated pipe 17, the tap water from the perforated pipe 17 to the blind groove 16a is not used. The outflow of water stops and the external water 15b flows through the perforated pipe 17 through the blind groove 16a.
Backflow to However, the external water 15b flowing backward is filtered by the crushed stone filter material 16a in the blind groove while passing through the blind groove 16. While the external water (river 15) flows backward to the perforated pipe 17 through the blind groove 16, the crushed stone filter material 16a in the blind groove 16 is clogged by silt contained in the external water. If the pressure of the groundwater around the pipe 17 becomes higher again, this clogging may occur.
It is washed with the dissolved water produced from the tap water 20 flowing out of the tank 7.

Furthermore the structure of the hydraulic control device 93 will be described in detail with reference to the left portion of FIG. The base end of the standpipe 92 connected to the perforated pipe 17 is disposed horizontally, and a control valve 91 having a discharge port 95 at a base end intermediate portion of the standpipe 92 and a base end of a branch pipe 96 spaced apart therefrom. A side inlet is connected, and the tip of the branch pipe 96 is arranged in parallel with the horizontal portion of the standing pipe 92, and the outlet of the tip of the branch pipe 96 is provided with a closed accordion-type bellows 97 that can expand and contract horizontally. An end-side inlet is connected, and the bellows 97 is concentrically disposed with a gap in a hollow cylindrical control cylinder 98 fixed laterally to the branch pipe 96. A proximal end inlet of an external water pressure introducing vertical pipe 99 projecting through the groove 16 and having an upper end outlet opened in the river water is connected, and a lower portion of the control cylinder 98 is guided so as to extend in the left-right direction. And a valve opening / closing operation arm 10
0 is guided and rotated by the guide slit.
A base end of a bracket 101 is fixed to the outer side of the front end of the telescopic bellows 97.
Opening / closing operation arm 10 at the tip of the valve and control valve 91
The zero-slit end portion is pivotally connected by a horizontal axis 102 arranged in the vertical slit. Control valve 9 having a standing pipe 92 connected to the perforated pipe 17 and a discharge port 95
1, branch pipe 96, bellows 97, and vertical pipe 9 for introducing external water pressure
9 and a control cylinder 98 constitute a water pressure control device 93. The water pressure control device 93 is configured such that the water level in the vertical pipe 92 is equal to the water pressure in the vertical pipe 99 for introducing external water pressure (the water level 15a of the river water 15).
When it is higher, the bellows 97 is extended and the control valve opening / closing operation arm 100 is rotated in the valve opening direction (clockwise), and the discharge port 95 is opened by the control valve 91 and the discharge port 95 is opened.
When the water level in the vertical pipe 92 is lower than the water pressure in the vertical pipe 99 for introducing external water pressure (the water level 15a of the river water 15), the bellows 97 is shortened, and the control valve opening / closing arm 88 is closed. The control valve 91 rotates the valve 95 in the valve direction (counterclockwise) to close the discharge port 95. In order to ensure the rotation of the control valve opening / closing operation arm 100, an appropriate surrounding wall (not shown) is provided so that the water pressure in the filter material 16a and the water pressure in the control device do not interfere with each other.

The water pressure in the porous tube 17 also moves up and down in accordance with the upper and lower water level in the water tank 24. If the amount of increase in water pressure in the perforated pipe 17 becomes excessive, it is not possible to cope with the problem by merely providing the standing pipe 92 provided with the control valve 91. Therefore, in order to prevent the amount of increase in water pressure in the perforated pipe 17 from being excessive. , Water tank 24
Immediately before the water supply pipe 55 that supplies water to the perforated pipe 17 is connected to the perforated pipe 17, a water supply suppression control device 90 that suppresses the following water supply is installed. The control device 90 controls the water pipe 5
An accordion-type bellows 84 connected to the branch pipe 55a branched from the water supply pipe 55 is provided in a control cylinder 85 in which a branch pipe 55a branched from the water supply pipe 5 and an external water pressure introduction vertical pipe 86 connected to external water are attached. If the water pressure is too high and the accordion-type bellows 84 extends, the valve opening / closing operation arm 88 hinged to the apex (tip) of the bellows pivots to turn the water supply control valve 83 and reduce water supply. When the water supply is reduced and the water supply pressure is reduced, the bellows 84 contracts and the water supply control valve 83 is opened to increase the water supply.

[0028] Next, with reference to the right-hand portion of FIG. 2 will be described in further detail the structure of the water supply amount control controller 90 provided in the water pipe 55 side. A water supply control valve 83 is provided at an intermediate portion of the water supply pipe 55 disposed horizontally in the blind groove 16, and a base end of a branch pipe 55 a branched from the water supply pipe 55 on the upstream side of the water supply control valve 83. The inlet is connected, and the distal end of the branch pipe 55a is arranged in parallel with the horizontal portion of the water supply pipe 55. The proximal end of the hermetic accordion type bellows 84 that can expand and contract horizontally is provided at the distal end of the branch pipe 55a. Side inlet is connected and its bellows 8
4 is concentrically disposed with a gap in a hollow cylindrical control cylinder 85 fixed laterally to the branch pipe 55a. The proximal end of the external water pressure introduction vertical pipe 86 having an open upper end outlet is connected to the lower end of the control cylinder 85, and a guide slit is provided so as to extend in the left-right direction.
The water supply control valve opening / closing operation arm 88 is rotated by being guided by the guide slit. A base end of a bracket 87 is fixed to the outside of the distal end of the extendable bellows 84. The distal end of the bracket 87 and the distal end of the water supply control valve 83 with a vertical slit of the water supply control valve opening / closing operation arm 88. Is a horizontal axis 89 arranged in the vertical slit.
It is pivoted by The water supply control valve 83 and the branch pipe 5
The water supply amount control device 90 includes the 5a, the bellows 84, the control cylinder 85, the external water pressure introduction vertical pipe 86, and the like. When the water supply pressure (water supply pressure) in the water supply pipe (water supply pipe) 55 is higher than the water pressure in the vertical pipe 86 for introducing external water pressure, the bellows 84 extends to open and close the water supply control valve. The arm 88 is rotated in the valve closing direction (counterclockwise) to throttle the water supply control valve 83 and to change the water supply pipe (water supply pipe) 5.
When the water supply pressure (water supply pressure) in 5 is lower than the water pressure in the external water pressure introduction vertical pipe 86, the bellows 84 is shortened,
The water supply control valve opening / closing operation arm 88 is rotated in the valve opening direction (clockwise) to open the water supply control valve 83. In order to ensure the rotation of the water supply control valve opening / closing operation arm 88, a surrounding wall (not shown) is provided as appropriate so that the water pressure in the filter material 16a and the water pressure in the control device do not interfere with each other. .

[How to Tap Water] The external water level 15a normally rises and falls twice a day due to tide.
The groundwater pressure in the blind groove 16 around the perforated pipe 17 increases and decreases several seconds later than the tide change. It takes several days for the water level in the aquarium 24 to decrease from the highest to the lowest. Since the control valve 91 opens and discharges water from the discharge port 95 while the tide level is in the process of lowering, the water pressure in the perforated pipe 17 drops several seconds earlier than the groundwater pressure in the blind groove 16 around the perforated pipe. The groundwater in the blind groove 16 flows into the perforated pipe 17. During the tide rising process, the control valve 91 is throttled, and the water pressure in the perforated pipe 17 rises several seconds earlier than the groundwater pressure in the blind groove 16 around the perforated pipe.
The water inside flows out into the blind groove 16. However, the internal water pressure of the perforated pipe 17 increases and decreases while always keeping the external water pressure in an excessive degree.

[ Pretreatment of Water Permeated into the Ground] Next, a pretreatment for producing air-dissolved water containing ultrafine bubbles used in the liquefaction prevention method of the present invention will be described. Micron-sized ultra-fine bubbles generated by passing compressed air through an ultra-fine filtration device for ceramics or the like are combined with water to form a resin porous tube 17 in a blind groove 16 at the upstream end.
If the micro-bubbles continue to be injected, the hydrodynamic pressure due to the infiltration water flow in the downstream direction in the foundation ground 4 is much larger than the force of the micro-bubbles trying to float upward by buoyancy, so the micro-bubbles will rise upward. Since it moves laterally in the downstream direction, airtight covering is not required on the surface of the bank body 14. This method often requires more than 1,000 m ³ of tap water every day. Therefore, in a place where industrial tap water can be easily obtained, it is desirable to provide a facility for aerating and supplying an appropriate amount of industrial tap water at a low rate.

[ Post-Treatment of Water Infiltrated into the Ground] In the middle of the downstream end drainage pipe 10a shown in FIG. 1, as shown in FIG. 11 and FIG. An overflow stand 103 connected by the drain pipe 10b and standing upright is provided in the manhole 104, and the overflow stand 1
The drain water overflowing from 03 is drained to the nearest sewer or rain sewer 10 by the drain pipe 10a. From the time when the air-dissolved water starts to penetrate into the ground through the upstream-side perforated pipe 17, there is a period during which the front end of the air-dissolved water reaches the downstream-side perforated pipe 17a by the permeation theoretical calculation based on the permeation test result of the ground soil. Once every week before and after the passage of time
Samples of water in 03 are collected, and the generation of microbubbles is visually measured or the dissolved air concentration is measured by a physical test method. By observing the presence of the microbubbles or the fact that the dissolved air concentration has reached the saturation level or more, it is confirmed that the front end of the dissolved air water has reached the downstream side porous tube 17a.
After the front end of the air-dissolved water reaches the downstream-side porous pipe 17a, a sufficient number of microbubbles are generated over the entire length of the permeation path of the air-dissolved water to prevent the ground liquefaction during an earthquake. Saving the maintenance and operating costs required to stop the operation of the compressed air generator for generating ultra-fine bubbles released to promote the generation and continue the long-term operation of the compressed air generator Can be achieved. If there is a component such as ferric oxide that removes oxygen in the dissolved air by a chemical reaction in the ground into which the air-dissolved water penetrates, the water that dissolves the oxygen-deficient air flows into the downstream porous tube 17a.
And the oxygen-deficient air is generated in the manhole 104 from the water in the overflow standing pipe 103 and may cause an oxygen-deficiency accident. If it is not possible to predict whether or not oxygen-deficient air will be generated, an oximeter 105 is mounted in the manhole 104, and when the oximeter 105 detects oxygen-deficient air, the oximeter 105 and the oximeter 105 are electrically connected. The ventilation fan 106 automatically operates to automatically ventilate the inside of the manhole 104 until the oxygen concentration recovers to a normal value, thereby preparing equipment for preventing the occurrence of an oxygen deficiency accident. However, if it is previously confirmed that there is no component that removes oxygen in the dissolved air such as ferric oxide by a chemical reaction in the ground of the permeation path of the dissolved air, the oxygen concentration meter 105 and the ventilation fan 106 Is unnecessary. River water flowing down the urban area has high turbidity, and the embankment facing the river and the riverbed ground are clogged by silt in the seepage water and the permeability is reduced. For example, in the case where the water permeability k of the unplugged sand is k = 5 × 10 ⁻² cm / sec, the water permeability k ′ of the clogged sand decreases to k ′ = 5 × 10 ⁻³ cm / sec. It is thought that it is. When the head h is 2 m and the permeation distance 1 is 70 m, the permeation speed v = kh / l = 0.005 × 2
/70=1.4286×10 ^-4 cm / sec = 0.1234 m / da
y, the front end of the permeate flow is the downstream end of the perforated pipe 17a.
Is the time required to reach l = v = 70 ÷ 0.1234 =
567day = It takes a long time of 1 year, 6 months and 19 days. The time required for the front end of the air-dissolved permeated water flow to reach the downstream end perforated pipe 17a based on the theoretical theory of permeation is long as described above. There is. Therefore, after the end of the calculation period, a sample of water in the overflow riser 103 and measurement of its dissolved air concentration are performed once a week at any rate.

As a device using tap water 20 instead of river water containing garbage and silt in the water to be penetrated into the ground, for example, as shown in FIG. 5, a device similar to a device for pouring water into a flush toilet is built in. The tap water 20 is stored in the water tank 24, and when the required amount of the tap water 20 is stored in the water tank 24, the drain valve 40 is automatically opened, and the water in the water tank 24 is passed through the perforated pipe 17 in the blind groove 16. It can penetrate into the ground.
When the water in the water storage tank 24 is discharged and penetrates into the ground through the perforated pipe 17 and the water storage tank 24 is almost empty, the drain valve 40
Automatically closes and the tap water 20 is always filled in an appropriate amount
4, the drain valve 40 is automatically opened and the same operation is repeated when the water level in the water storage tank 24 reaches a predetermined level. The size of the water storage tank 24 depends on the speed at which the tap water 20 permeates the ground, but the tap water 20 flows intermittently for several days and stops for several days. Such a device of the present invention is made of a highly durable material such as ceramics and reinforced plastics, and has a simple and durable structure that can be operated with little maintenance for decades or hundreds of decades. It requires little maintenance. However, since the embankment, seawall, and the like to which the method of the present invention is applied are public assets, they are placed under the control of a public organization that manages the related river, and the compressed air supply device 57 is used.
It is expected that a minimum amount of management work will be performed for maintenance and the like.

[0033] The next one form of the water storage tank 24 to the tap water 20 equipped with a device for the opening-closing operation for intermittently draining, 5 for the detailed structure and operation,
This will be described with reference to FIGS. A horizontal pipe portion on one end side of the water pipe 39 and a water supply vertical pipe 39a connected thereto are provided inside the upper portion of the vertical wall 24a in the water storage tank 24,
The lower part of the water supply vertical pipe 39a opens downward.

Further said bottom plate 24b in the water tank 24 is provided drainage vertical pipe 48a having a drain outlet 48, an intermediate portion of the drainage vertical pipe 48a, the lower outlet 4 of the overflow discharge pipe 48c
8d is connected to the upper opening 4 of the overflow pipe 48c.
8b is set to a higher level than the level at the position where the drainage vertical pipe 48a and the float 49 are raised in the water storage tank 24 and a level slightly lower than the lower end outlet of the water supply vertical pipe 39a. A float valve 4 having a support arm 47a is provided at an upper end opening (valve seat) of the drainage vertical pipe 48a.
7 is engaged, and the base end of the support arm 47a in the float bubble 47 is connected to the drain vertical pipe 48a.
The float valve 47 is configured to be rotatable in a valve opening direction and a valve closing direction about the horizontal shaft 47b. One end of a connecting strip such as a chain 50 is connected to the upper end of the float valve 47, and the other end of the connecting strip 50 is connected to the lower part of the float 49. An air reservoir 47c is provided inside the float bubble 47, and when the float valve 47 is seated at the upper end opening (valve seat) of the drain vertical pipe 48a, the water pressure is reduced.
Since the buoyancy is larger than that of No. 7, the float valve 47 operates in a closed state. However, the buoyancy of the float 49 at a level before the float 49 is submerged below the water surface 51 is set to be higher than the water pressure acting on the float valve 47 on the water surface 51 at the high level position.

[0035] Next tap water 2 to the reservoir 24 shown in FIG. 5
The operation of storing and draining water when 0 is supplied little by little will be described. The state of FIG.
0 indicates a state where water is being injected into the water storage tank 24, and the water surface 51 is rising. As the water surface 51 rises, the float 49 also rises. Note that the drain valve 40 is closed. FIG. 7 shows that when the float 49 rises with the water surface 51, the water tank 24 is filled with the tap water 20, and at the same time, the chain 50 connecting the float 49 and the float valve 47 is pulled by the float 49 so that the float valve 47 is pulled up. As a result, the drain valve 40 is opened, and the tap water 20 in the water storage tank 24 flows down through the drain port 48. The float valve 47 has an air reservoir inside, and floats in the tap water 20 in the water storage tank 24 by the buoyancy of the water, and keeps a state in which the drain port 48 is open.

FIG . 8 shows the state of the tap water 20 in the water storage tank 24.
Begins to drain, the float 49 starts to descend together with the water surface 51, and the drain valve 40
Since the amount of drainage from the container 49 is large, the float 49 has begun to descend. In the state shown in FIG. 9, the water surface 51 in the water storage tank 24 goes down, the buoyancy of water does not act on the float valve 47, the float valve 47 goes down, and the drain valve 4
0 indicates a closed state. Then, tap water 20 is stored in the water tank 24 through the water pipe 39. Note that FIG.
Although the float 49 is not shown in FIG. By using this device, tap water can be intermittently penetrated into the ground without using human power or electric power.

In the basement ground 4 of the river embankment 2, seawall, seawall 3 in the zero meter area 1 such as the downtown area of Tokyo or the Nobi plain, etc. The steady permeated water 8 is flowing toward 6. In the ground where a steady groundwater flow 7 exists, Japanese Patent Application No. 09-19520
Even if the air entrapment range is temporarily created by the method of blowing compressed air by the liquefaction prevention method of the patent application No. 4, the air in the microbubbles within the air entrapment range gradually dissolves in the groundwater flow. By leaving, the degree of saturation gradually increases and eventually loses the effect of preventing ground liquefaction during an earthquake.

[0038] Recent studies in water river flowing through the urban dissolved air close to the solubility saturation, bubbles are generated while continue to penetrate the embankment 2, the bubbles of the bank inner 6 Boiling by the ascending water flow 31 along the impermeable wall 25 is further intensified. Due to this boiling, a large amount of earth and sand is discharged from the embankment body 14, so that a cavity is formed in the embankment body 14, which causes deterioration of the embankment body 14.

As schematically shown in FIG . 1A, the embankment 2
The infiltration water flow containing air bubbles flowing down to the inner side of the bank 9 on the downstream side of the river is filled with a blind groove 16a filled with a filter material having an appropriate particle size distribution.
And drained to a sewer 10 such as a sewer or storm sewer through a perforated pipe 17a laid in a blind groove 16a.
Since the ascending flow 31 is deenergized, it is possible to prevent the bank body 14 from deteriorating due to boiling caused by the flow. If there is no appropriate sewer or culvert 10 near the inner side 6 of the embankment 2 or if the drainage 10 is not sufficiently deep, the inner side 6 of the embankment 14 is sufficiently deep for drainage. The culvert 10 needs to be installed separately.

As shown in FIG . 1, tap water 20 dissolved in an air-saturated or supersaturated state by aeration is stored in a water storage tank 24.
If water is accumulated in the water intermittently and penetrated into the ground, there is sufficient dissolved air in the tap water 20, and in the process of decreasing the water pressure from the inflow end to the outflow end, the tap water 20 It is considered that dissolved air elutes to form bubbles. However, even if there is a saturated or supersaturated dissolved air in the tap water 20 as described above, no bubbles are formed unless fine particles serving as nuclei for bubble generation exist on the permeation path 26. At the outlet end of the compressed air supply pipe 27 shown in FIG. 1, compressed air 28 is blown out as ultrafine bubbles through an ultrafine filter material such as ceramics, and these ultrafine bubbles serve as nuclei for bubble formation. The air eluted on the infiltration path 26 is distributed in the groundwater in the form of microbubbles, and the dissolved water is constantly replenished. Therefore, the ratio of the volume occupied by the air in the infiltrated water to the infiltrated water volume, that is, the degree of saturation decreases. If you do, it will not improve. Then, depending on the particle size distribution and N value of the ground soil, it is considered that if the saturation is maintained semipermanently at 85% or less, liquefaction of the ground during an earthquake can be prevented.

As shown in FIG. 3, tap water 20 which is saturated or supersaturated with air is dissolved by the same method as the levee 2 liquefaction prevention method as described above. It is considered that by infiltrating into the ground 4, the saturation of groundwater in the ground can be kept at a low level, and the liquefaction of the foundation ground 4 of the seawall 3 due to the earthquake can be prevented.
The problem with the seawall 3 around the zero meter area 1 is that when the rising seepage water flow 31 occurs along the wall surface inside the embankment 6, the rising seepage water flow 31 causes a boil to cause sediment from the riverside ground 32. There is a possibility that the base ground 4 of the seawall 3 is discharged and deteriorated.

In order to prevent the deterioration of the foundation ground 4 due to the boiling, the filter material 16a having an appropriate particle size distribution similar to that installed on the inner wall 25 of the embankment in the case of the embankment 2 is used.
Is filled in the blind groove 16, and the permeated water flow is collected in the blind groove 16 filled with the filter material 16a, and as shown in FIG.
It is considered that the deterioration of the foundation ground 4 due to boiling can be prevented by draining the water to the drainage 10 such as a sewer or a rain sewer through the perforated pipe 17a laid in the inside.

In the case of the seawall 3 as shown in FIG . 3, as shown in FIG .
It is good to intermittently penetrate into the ground. In the method shown in FIG. 3 as well, it is necessary to mix ultra-fine bubbles generated by passing compressed air through an ultra-fine filter such as ceramics into water to be penetrated into the ground. It is the same as the case of the construction method shown.

The biggest disadvantage of the gravity type revetment wall 33 as shown in FIG . 4 is that the replacement sand 35 which supports the foundation rubble 34 during an earthquake.
Is easily liquefied. A liquefaction prevention method for a revetment wall of this type is, as schematically shown in FIG. 4, first connected to a compressed air supply source by switching a valve and supplying or discharging a fluid (air). A switchable air supply / exhaust pipe 36 is disposed in the displacement sand 35 below the gravity type revetment wall 33 to create an air entrapment range composed of microbubbles in the displacement sand 35, and at the same time, to the rear ground 38 of the caisson 37. Air is blown in using the same device as the air supply / exhaust pipe 36 to create an air entrapment range in which the degree of saturation of groundwater is 85% or less, depending on the particle size distribution of ground soil, N value, etc. The tap water 20 which dissolves air in a saturated or supersaturated state is constantly or intermittently introduced from the air supply / exhaust pipe 36 on the side 5 (a pipe which becomes an air blowing pipe or an exhaust pipe or a collecting pipe by switching a plurality of valves). There is a way to do this. The reason why the tap water that dissolves the air is permeated into the displacement sand 35 after the creation of the air mixing range is that the air is sufficiently dissolved even if fine bubbles are formed in the displacement sand 35 in advance. If no water permeates and circulates from the external water area into the displacement sand 35, the air in the bubbles is dissolved into the permeation flow, the saturation increases, and the effect of preventing ground liquefaction during an earthquake is lost. A supply / exhaust pipe 36 for flowing tap water dissolved in a saturated or supersaturated state into the ground is provided with a large number of supply / exhaust pipes which rise in external water (river water 15) at the leftmost end on the river water 15 side in FIG. The air is allowed to flow naturally through a row of air supply / exhaust pipes composed of 36. In this case, in order to allow the water that dissolves the air to flow in naturally, the water surface in the air supply / exhaust pipe 36 at the leftmost end on the river water 15 side is a control valve shown in FIG. The pipes 91 are connected to each other to prevent the water level in the air supply / exhaust pipe 36 from rising above the water surface 15a of the external water. When a gravity type quay as shown in FIG. 4 is located around the zero meter area, there is a natural groundwater flow from the external water through the quay foundation ground. Since a permeation flow of water that dissolves air is generated in the same manner as a natural groundwater flow, there is no need to perform forced water supply unlike the case where compressed air is blown into the ground to perform preliminary.

In the method shown in FIG . 4, since a sufficient number of microbubbles have already been generated on the tap water distribution channel,
There is no need to mix ultrafine bubbles generated by passing compressed air through an ultrafine filter such as ceramics into the water that penetrates into the ground. Air supply pipe 3 on the air supply side shown in FIG.
The exhaust pipe 36 on the exhaust side and the exhaust pipe 36 may be configured as separate pipes. FIG. 10 shows an embodiment that can be used as the air supply / exhaust pipe 36 shown in FIG. Explanation will be made based on the example shown. In the specific example shown in FIG. 10, an air supply / exhaust pipe 36 formed by joining an air supply pipe 61 having an air supply valve 60 and connected to an air supply apparatus and an exhaust pipe 63 having an exhaust valve 62 and connecting to the exhaust apparatus. Are used as the air blowing pipe 64 and the air collecting pipe 65. Further, the air supply / exhaust pipe 36
Has a water supply valve 66 in the water supply / exhaust pipe 36, and guides a water supply pipe 67 connected to a high-pressure water supply apparatus, so that both pipes 2
A heavy pipe, a water pipe 67 is connected to a first pipe body 70 having a blade portion 68 for excavating the ground and a water ring-shaped nozzle 69 mechanism, and further, the water supply / exhaust pipe 36 is not communicated with the first pipe body 70. And a second air supply / exhaust strainer 71
It is configured to be connected to the tube body 72 by a screw connection portion 73.

Further , the pipe 70 is provided with a water collecting hole 74 for taking in water jetted into the ground from the water ring nozzle 69 separately from the water ring nozzle 69. The water ring-shaped nozzle 69 is composed of a substantially conical block 75 held with a gap inside the first tube 70 so as to spray water in a ring shape. A ring valve 76 that is opened by water pressure from the water collecting hole 74 is provided at the upper end of the ring valve 76. The ring valve 76 is fitted and closed in the annular groove by its own weight or a pull-down spring (not shown), but is opened by the water pressure from the water collecting hole 74.
The water that has entered through the water collecting hole 74 is discharged upward. When using the air-dissolved water by the apparatus shown in FIG. 10, the air blowing pipe 64 and the combined use air supply / exhaust pipe 65 are used for water supply,
What is necessary is just to use the air-supply / exhaust strainer 71 for water-supply.

As described above, since the apparatus shown in FIGS. 1, 3 and 4 uses tap water, the river 15
Compared to the case where water is used, there is no need to perform maintenance such as cleaning and removing clogging if silt accumulates in the filter material for removing silt and clogging occurs. Becomes very simple.

When implementing the present invention, FIG.
As shown in the figure, when the water pressure of the tap water 20 or the tap water pressure in the aeration apparatus 20a is low, the water pressure is increased by a pump or the like, and the air formed by spraying and spraying in the aeration apparatus 20a is formed. Is made into tap water 20 dissolved in a saturated state or a supersaturated state, and this tap water 20 is supplied to the water storage tank 24 by a water pipe (or supply pipe) 39.

[0049] When carrying out the respective embodiments, as described above, although usually one reservoir 24 will be water in one of the perforated tube 17, these installation interval scale of embankments or the like, the present It depends on the facilities such as sluices attached to the dike etc. other than the facilities implementing the invention, the soil quality of the embankment body 14 and the foundation ground, etc., but usually, the interval of 50 m to 100 m in the longitudinal direction of the embankment body 14 It is preferable to set it up at a location.

In place of the tap water 20 as described above, river water 15 which sufficiently dissolves air can be used as the water to be penetrated into the ground, but the river water 15 generally contains silt and trash, and The use of a river is not preferable because the gap between the filter materials in the blind groove 16 may be clogged and the smooth distribution of water that penetrates into the ground may be hindered.

[0051]

According to the first aspect of the present invention, the range in which microbubbles are mixed into the ground is simply increased by simply allowing air-dissolved water containing ultrafine bubbles to continue to penetrate into the ground having weak adhesion. The groundwater saturation of the ground within the range of microbubble contamination can be reduced by simple means such as simply infiltrating air-dissolved water containing ultrafine bubbles into the ground where groundwater flows constantly. Liquefaction is reduced to a level that does not occur during an earthquake, and liquefaction is prevented.Therefore, it is possible to eliminate the problem of land subsidence that occurs when lowering the groundwater level to reduce saturation, and that the liquefaction of the ground Due to the structure supported by the foundation on the ground,
It has an excellent effect of not moving, tilting or collapsing. Further, in the case of the liquefaction prevention method of the present invention, since only air-dissolved water containing ultra-fine bubbles is permeated, construction and maintenance are easy, and there is no danger of inducing land subsidence. It has the effect that it can be implemented even in the region. Furthermore, upstream blindness
The upper surface of the groove is covered with an impervious coating, and the blind groove at the downstream end
Dissolved water containing microbubbles infiltrating the porous tube in the ground
To collect water and drain it to the nearest drain or sewer.
Ensures the flow of dissolved air containing ultra-fine bubbles on the upstream side
Air containing residual microbubbles
Collect and collect the dissolved water on the downstream side without fail.
Flows down into the storm sewer, so the boil
This to prevent the deterioration of the dam body 14 or the underlying ground 4 by the ring
Can be.

[0052] According to the invention of claim 2, easily ultrafine bubbles micron sized ultrastructural filtration apparatus equipped with ultrafine filtration layer is mixed with air dissolved in water, in blind grooves provided on the upstream end It can flow into a perforated tube.

[0053] According to the third aspect, when infiltrating tap water for dissolved air in the ground, the tap water approximately reservoir height that matches the height of the bottom to the secondary sea level reservoir Reservoir, the water stored in the water tank is sent to make tap water mixed with ultra-fine bubbles generated through a fine filtration device such as a porous stone, and the tap water mixed with the ultra-fine bubbles is supplied to the upstream end. It is made to flow into the perforated pipe in the blind groove provided, and the water pressure in the perforated pipe can be sent at a relatively low water pressure without significantly increasing the water pressure of the external water, so that the water pressure inside and outside the perforated pipe can be reduced. Balancing can be done easily using relatively small devices.

According to the fourth and fifth aspects of the present invention,
The ultra-fine bubbles generated by the ultra-fine filtration device can be mixed into the tap water stored in the water storage tank, and can be permeated into the ground through the porous tube on the upstream end side. The liquefaction can be prevented by lowering the degree of saturation of groundwater in the range in which the microbubbles are mixed so that liquefaction does not occur during an earthquake.

[0056] According to the invention of claim 6, connects the proximal end of the standpipe with a control valve having a water discharging function perforated pipe 17,
The control valve having the water discharging function prevents the water pressure in the perforated pipe 17 from becoming higher than the underground water pressure around the perforated pipe 17, so that the air-dissolved water is not diffused from the perforated pipe 17 into the external water. Can be efficiently penetrated from the porous tube 17 into the ground.

[0057] According to the invention of claim 7, when water water in the porous tube, in order to suppress from becoming excessive than the water pressure in the porous tube 17 to groundwater pressure surrounding, connected to a perforated pipe Since the water supply pipe is provided with a water supply amount control device equipped with a water supply amount control valve, the air-dissolved water is directed from the perforated pipe 17 into the ground without dissipating the air-dissolved water from the perforated pipe 17 to the outside water. Can penetrate well.

[Brief description of the drawings]

FIG. 1A is a sectional view of a dike around a zero meter area to which a liquefaction prevention method of the present invention is applied. (B) is an enlarged longitudinal side view showing the vicinity of the ultrafine filtration device in (a).

FIG. 2 is an explanatory view showing a water supply amount control device provided to be connected to a perforated pipe and a water pressure control device for controlling water pressure in the perforated pipe according to the present invention.

FIG. 3 is an explanatory cross-sectional view showing a method for preventing liquefaction of the foundation ground of a tide barrier along a zero meter area.

FIG. 4 is a cross-sectional explanatory view showing a method of preventing liquefaction of a foundation ground of a gravity type revetment wall around a zero meter area.

FIG. 5 is an explanatory diagram showing a water storage tank provided with an automatic opening / closing device for a drain valve.

FIG. 6 is an explanatory diagram showing a state where water is stored in a water storage tank.

FIG. 7 is an explanatory diagram showing a state in which a drain valve is opened and draining from a water storage tank is started.

FIG. 8 is an explanatory diagram showing a state where the drain valve is being drained from the water storage tank while being kept open by buoyancy.

FIG. 9 is an explanatory diagram showing a state in which the drain valve has lost its buoyancy, is closed by its own weight, and is being supplied with water from a faucet.

FIG. 10 shows a process for blowing compressed air into the ground.
Alternatively, it is a cross-sectional explanatory view of a water pipe structure for flowing and dissolving air-dissolved water mixed with ultrafine bubbles into the ground.

FIG. 11 is a vertical cross-sectional side view showing a drainage facility provided with an overflow standing pipe for observing that a front end of dissolved air water has reached a downstream porous pipe.

FIG. 12 is a sectional view taken along line II of FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Zero meter area 2 Embankment 3 Embankment 4 Seawall 6 Riverside 6 Inner embankment 7 Groundwater flow 8 Infiltration water 9 Embankment inner bottom 10 Drainage culvert 10a Drainage pipe 10b Drainage pipe 11 Embankment slope 12 Slope protection 13 Non Water-permeable coating 14 Embankment body 15 River water 16 Blind groove 16a Filter material 17 Perforated pipe 17a Downstream (inside of the embankment) perforated pipe 20 Tap water 20a Tap water aeration apparatus 24 Water storage tank 25 Water barrier 26 Permeation path 27 Compressed air supply pipe 28 Compressed air 31 Ascending water flow 32 Riverside ground 33 Gravity-type revetment wall 34 Foundation rubble 35 Replacement sand 36 Air supply / exhaust pipe 37 Caisson 38 Back ground 39 Water pipe 40 Drain valve 47 Float valve 48 Drain port 49 Float 50 Chain 51 Water surface 55 Water pipe or water supply pipe 55a Branch pipe 56 Ultrafine filtration device 56a Ultrafine filtration layer 57 Compressed air supply Installation 58 Miscellaneous stones 59 Submerged ground 60 Air supply valve 61 Air supply pipe 62 Exhaust valve 63 Exhaust pipe 64 Water supply valve 65 Collecting pipe 66 Air blowing pipe 67 Water supply pipe 68 Blade part 69 Spray water ring nozzle 70 First pipe 72 Second pipe Body 73 Joint 74 Water collecting hole 75 Conical block 76 Ring valve 77 Inflatable seal 78 Joint 79 Joint 80 Screw joint 81 Support arm 83 Water supply control valve 84 Bellows 85 Control tube 86 Vertical pipe for external water pressure 87 Bracket 88 Valve opening / closing operation arm 89 Horizontal axis 90 Water supply amount control device 91 Control valve 92 Standing pipe 93 Water pressure control device 95 Outlet 96 Branch pipe 97 Bellows 98 Control tube 99 External water pressure introduction vertical pipe 100 Control valve opening / closing operation arm 101 Bracket 102 horizontal axis

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02D 3/10 E02D 3/11 E02D 3/12 101

Claims (7)

(57) [Claims] (1) An air-dissolved water containing ultra-fine bubbles is continuously infiltrated into a ground having a weak adhesive strength to form a mixed range of micro-bubbles in the ground. A perforated pipe is provided in a blind groove whose upper surface is covered with a permeable coating, air-dissolved water containing ultrafine bubbles flows into the perforated pipe, and the perforated pipe in the blind groove provided at the downstream end of the steady groundwater flow Air-dissolved water containing microbubbles penetrating the ground is collected in pipes, and the collected water is allowed to flow down to the nearest sewer pipe or storm sewer, thereby embankment or seawall surrounding the zero meter area. Earthquake caused by infiltration of air-dissolved water into the ground, characterized by lowering the degree of groundwater saturation of the ground in the area where the microbubbles are mixed to the extent that liquefaction does not occur during an earthquake When liquefaction prevention method. 2. In order to mix micron-sized microbubbles into air-dissolved water, the air is generated by flowing compressed air through an ultrafine filtration device having an ultrafine filtration layer such as a porous stone made of ceramics or the like. Tap water mixed with ultra-fine bubbles is flowed into the perforated pipe in the blind groove whose upper surface provided at the upstream end of the existing steady groundwater flow is covered with an air-impermeable coating by means of water supply. A method for preventing liquefaction during ground earthquake by infiltrating air-dissolved water into the ground according to claim 1 . 3. When tap water in which air is dissolved is penetrated into the ground, tap water is stored in a water tank whose height at the bottom of the water tank substantially coincides with the middle sea level, and the water is stored in the water tank. In the process of flowing the tap water into the perforated pipe provided at the upstream end of the steady groundwater flow, the tap water is mixed with the ultra-fine bubbles generated through the ultra-fine filtration device, and the ultra-fine bubbles are mixed. tap water, by osmotic flows into the ground through the perforated pipe in blind grooves provided on the upstream end, or claim 1, characterized in that to generate microbubbles groundwater
Or the method for preventing liquefaction of ground during an earthquake by infiltrating the dissolved water of air according to item 2 or 2 into the ground. 4. When tap water in which air is dissolved penetrates into the ground, the tap water is stored in a water storage tank, and the water stored in the water storage tank is generated through an ultra-fine filtration device to generate water mixed with ultra-fine bubbles. The water is allowed to penetrate into the ground through the perforated pipe in the blind groove provided at the upstream end to reduce the saturation of groundwater in the area where microbubbles are mixed in the ground to the extent that liquefaction does not occur during an earthquake. Claim 1, wherein
2. A method for preventing liquefaction of an earth during an earthquake by infiltrating the dissolved water of air according to any one of 2 and 3 into the ground. 5. When tap water in which air is dissolved is permeated into the ground, the tap water is stored in a water storage tank, and when the water storage tank is full, a drain plug of water flowing into the perforated pipe in the blind groove is provided. Is automatically opened for a certain period of time, and tap water mixed with ultra-fine bubbles generated by the ultra-fine filtration device penetrates into the ground through a perforated pipe in a blind groove provided at the upstream end of the groundwater flow to penetrate the ground. The air-dissolved water according to any one of claims 1, 2, 3, and 4, wherein the liquefaction is prevented by reducing the degree of saturation of groundwater in the range in which the microbubbles are mixed so as not to cause liquefaction during an earthquake. Method to prevent liquefaction of the ground during an earthquake by infiltrating the ground. 6. Connect the proximal end of the standpipe with a control valve having a water discharging function perforated pipe 17, the control valve having the water discharge function, groundwater perforated tube 17 surrounding the water pressure in the perforated pipe 17 請, characterized in that so as not higher than pressure
A method for preventing liquefaction of a ground during an earthquake by infiltrating the air-dissolved water according to any one of claims 1, 2, 3, 4, and 5 into the ground. 7. When water is supplied to the perforated pipe, the perforated pipe 17 is used.
The water pressure inside to suppress to become excessive as compared with the underground water pressure surrounding the water supply pipe to be connected to the perforated pipe, and providing a water supply amount control apparatus having a water supply control valve 請
The method for preventing liquefaction of an earth during an earthquake by infiltrating air-dissolved water into the ground according to any one of claims 1, 2, 3, 4, 5, and 6 .