JP2015004262A - Desaturation ground improvement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desaturation ground improvement device capable of economically performing ground improvement for preventing liquefaction through desaturation by injection of a microbubble liquid or the like, and allowing injection design, injection control, and confirmation of injection effect to be easily performed.SOLUTION: A desaturation ground improvement device is used to desaturate a ground by injecting an air-containing fluid such as microbubble into the ground under a groundwater table through an injection pipe. The desaturation ground improvement device is equipped with a pressure injection device, a liquid feeding pipe, and the injection pipe for injecting the air-containing fluid, and a predetermined number of fine boreholes having a predetermined bore diameter are provided in tip parts or in middles of the liquid feeding pipe and the injection pipe. An orifice is formed in such a manner that the sum of areas of the boreholes is smaller than the cross-sectional area, and the desaturation of the ground is performed by injection with a liquid feed quantity determined by the injection pressure in the liquid feeding pipe, the bore diameter of the boreholes, and the number of boreholes and an air quantity contained during the liquid feeding.

Description

  The present invention makes it possible to economically improve the ground to prevent liquefaction due to desaturation by injecting an air-containing fluid such as microbubble liquid, and to easily perform injection design, injection management, and confirmation of the injection effect. The present invention relates to an unsaturated ground improvement device.

  When loosely deposited saturated sand is subjected to repeated shear stress due to earthquake motion, the structure between sand particles is disturbed, and the intergranular meshing gradually disengages, resulting in an increase in excess pore water pressure and a decrease in effective stress. As a result, the sand ground exhibits liquid properties (liquefaction phenomenon). As a result, sand sand, uneven settlement of structures, lateral flow, earthquake oscillation, fluid failure of slopes, reduced bearing capacity, revetments and retaining walls Damage due to liquefaction such as destruction of the pipe and floating of the buried pipe occurs.

  In preparation for such a liquefaction phenomenon, ground improvement by chemical injection is widely implemented, but chemical injection is intended to prevent liquefaction by filling the gaps between sand particles with gel to suppress the increase in pore water pressure. To do.

JP 2010-209633 A Japanese Patent No. 4899164

  In recent years, a method has been proposed in which an air-containing fluid such as a microbubble liquid (microbubble liquid) having a diameter of 5 to 100 μm or air is injected into the ground to desaturate the ground to prevent liquefaction (Patent Document 1). (See Patent Document 2 and FIG. 1)

  In this method, by injecting microbubbles and air into the ground, the gas volume contraction function is effectively generated against the shearing force caused by the earthquake motion, and the increase in the pore water pressure is suppressed and the liquefaction can be prevented economically. . Fig. 2 shows the soil quality of the ground targeted for liquefaction countermeasures by injection.

The most difficult issues in the injection method of gas-containing liquids such as microbubble mixed liquid and air injection are
(1) When injecting air into the ground or injecting bubble-containing liquid into the ground, it is difficult to grasp the injection volume and injection speed (injection volume per minute), and it is also possible to use an infusion liquid pump containing air. It is difficult or inaccurate to measure with liquid feeding or electromagnetic flowmeter. That is, injection management is difficult.
(2) It is difficult to grasp the amount of injected air in the ground, and therefore it is difficult to grasp the degree of unsaturation.

(3) It is unclear whether the microbubbles or air injected into the ground will be retained between the soil particles in a finely divided state, and will immediately become a mass of air in the ground and deviate to the ground surface. That may end up.
(4) It is difficult to measure the degree of desaturation of the injected ground.

(5) There is a problem that the ground once desaturated by injecting an air-containing fluid may cause the air to leak out of the target range over time or dissolve in groundwater to reduce desaturation. is there.

  Therefore, it is difficult to determine how much the injection is effective for the desaturation effect. This is because it is unclear how bubbles and gases behave in the ground. For this purpose, a design method, an injection management method, and an effect confirmation method for injecting bubbles or gas into the ground to satisfy a predetermined degree of unsaturation have not yet been established. In addition, the durability of the unsaturated ground is unknown.

According to the applicant's research, as described above, the problem of liquefaction countermeasure work using air-containing fluid such as microbubble liquid,
(1) Microbubble liquid or air injection into the ground does not involve gelation unlike conventional solidified injection liquids, so it is unclear where the injected air-containing fluid will go. If the injection speed is high, it does not permeate between the soil particles and deviates to the ground surface or a rough layer, and does not permeate the soil layer to be liquefied (see FIG. 3).

(2) In order to adsorb an air-containing fluid between soil particles, air must be atomized and injected into the ground. To that end, the discharge speed must be reduced and the soil particles must penetrate. Therefore, the construction efficiency is lowered and practicality cannot be obtained (see FIG. 3).

(3) When microbubble liquid or air is injected into the ground, it is difficult to measure the injection volume and injection speed with an injection pump or with a flow meter. This makes injection management difficult.

(4) In the desaturation method that forms an unsaturated ground by injecting microbubble liquid or air into the ground, the method of injecting gas directly into the ground is a problem that the underground air is hardened and tends to escape to the ground surface. It is thought that there is. When the microbubble liquid is injected into the ground, the particle size of the microbubble is 5 μm to 100 μm, and it is considered that fine bubbles (microbubbles) are easily adsorbed between the soil particles (see FIG. 1 (c)). . However, even if the microbubbles are formed by the ground microbubble generator, it is unclear whether the microbubbles are formed when injected into the ground. There is a possibility that the microbubbles have become a mass of air in the pipeline from the microbubble generator to the tip of the injection tube.

(5) The desaturation method is trying to evaluate the improvement effect by the degree of saturation of the ground, but it is difficult to confirm how much desaturation will occur if it is injected into the ground. Methods of measuring with a resistivity or soil moisture meter have been proposed as methods for measuring desaturation due to air, but the relationship between the amount of gas injected and soil desaturation is unknown because the behavior of air and bubbles in the ground is unknown. However, it is difficult to confirm the entire desaturation of the injection effect ground, and therefore it is impossible to confirm the construction management, the planned injection design and the effect.

(6) Since the injected gas deviates into the air or groundwater in the ground and dissolves, it is thought that the degree of unsaturation is reduced, so it maintains desaturation for a long time against earthquakes that do not know when it occurs Difficult to do.

  The present applicant has completed the present invention by solving the above-described problems in the injection of microbubble liquid and air (bubble injection liquid).

  The desaturated ground improvement device of the present invention is a ground improvement device used in a ground improvement method for injecting an air-containing fluid such as microbubbles through an injection pipe into the ground under the groundwater surface, and desaturating the ground. A pressure injection device for injecting the contained fluid, a liquid feeding pipe, and an injection pipe, provided with pores having a predetermined hole diameter and a predetermined number of holes at the tip or in the middle of the liquid feeding pipe and the injection pipe, The orifice is formed by making the total area of the pores smaller than the cross-sectional area of the injection tube, and the liquid supply amount determined by the injection pressure of the liquid supply in the liquid supply tube, the pore diameter and the number of holes, and the liquid supply It is characterized in that the ground is desaturated by injecting with the amount of air contained therein.

  In addition, the ground improvement device used in the ground improvement method for injecting microbubble liquid into the ground under the groundwater through an injection pipe and desaturating the ground, is an additional device for injecting air-containing fluid such as microbubble liquid. A pressure injection device and a plurality of injection pipes, wherein the air-containing fluid is distributed from the pressure injection device to the plurality of injection pipes, and a plurality of locations of the injection pipe to the injection pipe tip portion The orifice is formed by making the total area of the pores smaller than the cross-sectional area of the injection tube, and the pore has a predetermined hole diameter and a predetermined number of holes so that a predetermined ejection amount is obtained. It is characterized by injecting a predetermined amount of air-containing fluid into the ground to inject a small amount from one hole and at a low pressure, and to desaturate the ground with a large discharge amount from the whole. It is what.

  The ground improvement method using the desaturated ground improvement device of the present invention injects microbubble liquid into a predetermined area of the ground where liquefaction is expected and injects the ground into the ground below the groundwater surface via an injection pipe. In the ground improvement method for preventing liquefaction by saturation, using a ground improvement device comprising a pressure injection device for injecting microbubble liquid, a liquid supply tube and an injection tube, the liquid supply tube and the injection An amount of air released into the ground by providing a pore with a predetermined pore diameter at a predetermined position of the pipe, injecting an injection liquid amount determined from the injection pressure in the liquid supply pipe and the pore diameter of the pore into the ground below the groundwater surface The ground is desaturated by (FIGS. 2, 3, 4, and 5).

  Since general injection requires injection at a low pressure, the pore size and number of pores at the tip of the injection pipe are the sum of their areas so that they can penetrate at low pressure so as not to cause pressure by themselves. Is set larger than the cross section of the tube. This case is referred to as a non-orifice discharge port.

  On the other hand, in the present invention, the pore diameter and the number of pores at the tip of the injection pipe are such that the sum of the areas is smaller than the cross-sectional area of the injection pipe so that the pressure in the pipe can be maintained sufficiently. To do. In this case, the discharge amount into the ground is determined by the pressure in the injection pipe, the diameter and number of pores, and the permeation resistance pressure of the ground. This case is called an orifice discharge port.

  The position of the pore that generates the internal pressure is not the tip discharge part of the injection pipe, but the branch part of the injection pipe that is not the tip discharge part, and is provided in the middle of the injection pipe so that sufficient pressure is applied upstream of the pore. It may be generated (the pore in this case is called an orifice).

  Even in this case, in order to inject the air-containing liquid into the ground in the form of fine particles without the air passing through the orifice being solidified in the injection pipe, a plurality of pores (non-orifice outlet) are provided at the outlet of the inlet pipe. Is preferably provided. Of course, an orifice discharge port may be provided instead of the non-orifice discharge port.

  If an orifice is provided in the ground part of the injection pipe and a pressure gauge and a flow meter are provided downstream thereof, the measured values indicate the injection pressure and flow rate of the injection solution injected into the ground, which is preferable for injection management. .

  In addition, if the relationship between the orifice, hole diameter, number, liquid feeding pressure, ground penetration resistance pressure, and discharge amount is confirmed in advance, there will be a region where the ejection amount hardly changes even if the penetration resistance pressure changes. (FIGS. 6 to 7), the injection amount can be grasped without using a pressure gauge or a flow meter, and therefore the amount of air injected into the ground, and hence the degree of unsaturation, can be grasped.

  Also, in the ground improvement method to prevent liquefaction by injecting microbubble liquid into the predetermined area of the ground where liquefaction is expected through the injection pipe to the ground under the groundwater surface and desaturating the ground, Distributing the air-containing fluid from the pressurized injection device to a plurality of injection pipelines using a ground improvement device comprising a pressurized injection device for injecting microbubble liquid and a plurality of injection tubes, and the injection tube Provided with pores at several locations in the injection pipe to the tip of the injection pipe, the pores are located in the ground below the groundwater surface with a predetermined hole diameter and a predetermined number of holes to obtain a constant amount of ejection. Inject a fixed amount of microbubble liquid.

The inventor
(1) It was found that if the amount of air injected into the ground could be managed, the degree of unsaturation could be grasped from the amount of air in the injection target area.
(2) We found a method that can measure air volume without using a flow meter or pressure gauge.

(3) Ascertain the discharge volume from the relationship between the pressure difference between the liquid feeding pressure from the pressurizing device for air-containing fluids such as microbubble liquid and the pressure in the injection pipe, and the pore diameter of the pores provided in the injection pipe. The degree of unsaturation can be estimated by grasping the amount of air injected into the ground (see FIGS. 5 to 9).

(4) Even if microbubbles are gathered in the injection pipe, the microbubbles are retained between the soil particles in the ground by making the air-containing liquid into fine particles at the tip of the injection pipe and injecting it into the ground. We focused on what we can do. In other words, it has been found that a predetermined amount of air may be fed into the injection pipe and then injected into the ground with fine particles (see FIGS. 1 (c) and 10 (d)).

(5) In order to make air fine particles, it must go through the pores, so it must be injected with a small discharge amount, the construction capacity becomes small, and the discharge from the pores is pressure However, by increasing the number of pores or simultaneously injecting from multiple injection tubes, a small amount of injection is performed so that the air does not deviate. By performing a predetermined amount of injection simultaneously through a plurality of injection pipes, it is possible to increase the work efficiency by increasing the entire ejection amount without increasing the pump pressure (see FIG. 3).

(6) Even if the air desaturates the ground in the ground, it is assumed that the air will deviate to the surroundings over time or dissolve in the groundwater to reduce the degree of unsaturation. We found a way to prevent and reinject.

  The present inventor has solved the conventional problems of the gas-containing liquid described above by elucidating the problem in injecting the air-containing liquid from the pores and the function of simultaneously injecting the air-containing liquid from the plurality of pores. It is.

  As described above, since the air-containing liquid does not gel, it must be possible to control the injection with a small amount of liquid fed per hole. Otherwise, the ground will crack or deviate from the target range.

  Therefore, the air-containing liquid must be slowly and slowly permeated at a low pressure over time (FIGS. 2, 3, and 4). For this reason, it is desirable to feed liquids simultaneously or continuously to a plurality of injection pipes or discharge holes with a small liquid feed amount per hole (FIGS. 13 to 25).

Examples of a basic liquid feeding system for this purpose are shown in FIGS. The injection principle by the orifice is shown in FIGS. The orifice is usually suitable for obtaining an ejection amount of 0.5 to 10 liter / min per hole from a pore of 0.5 to 5 mm at a pump pressure of 0.01 to 4 MPa / cm ² . Therefore, it is suitable for injecting into the ground which is liable to be liquefied and infiltrating between the soil particles without breaking, and holding it in a predetermined region (FIGS. 2, 3, and 26 (d)).

5 to 9 show the relationship among the liquid feeding pressure (P ₀ ), the nozzle diameter (a), the ejection amount (liter / min), and the permeation resistance pressure (P ₁ ) in a pipe line provided with an orifice.

  FIG. 5 (a) shows the test apparatus, in which a pipe line provided with a nozzle diameter (a) is inserted into the outer pipe, packers are provided on both sides of the nozzle, and a pressure regulating valve is provided in the pipe line from the outer pipe. This is a structure for adjusting the opening of the pressure regulating valve.

The liquid is fed into the pipeline with a pump, and the pressure (P ₀ ) and flow rate are measured. The pressure and flow rate of the jetted liquid ejected from the nozzle diameter (a) are measured by adjusting the opening of the pressure regulating valve. The pressure P _{1 at} that time is the permeation resistance pressure, and the flow rate at that time is the ejection amount.

FIG. 5B shows the relationship between the liquid supply pressure (P ₀ ), the nozzle diameter (a), and the ejection amount when the pressure regulating valve is fully opened, that is, when liquid is supplied in the air. When the pump pressure P ₀ is constant, the smaller the nozzle diameter, the smaller the ejection amount. The higher the pressure, the larger the nozzle diameter, the larger the ejection amount.

FIG. 6 shows the relationship between the nozzle diameter a of the orifice, the differential pressure ΔP, and the ejection amount per minute. The differential pressure ΔP is the difference between the pumping fluid pressure P ₀ and the resistance pressure P ₁ downstream of the orifice. The larger the differential pressure and the larger the nozzle diameter, the larger the ejection amount. As the resistance pressure P ₁ increases and approaches the liquid feeding pressure P ₀ , the ejection amount approaches 0 (FIG. 7).

In the state of FIG. 7, if the resistance pressure P ₁ ≈0, ΔP = P ₀ , but if the permeation resistance is large, ΔP becomes small and the ejection amount becomes small. However, Figure 7, the pump pressure if is sufficiently small osmotic resistance pressure P ₁ compared to (P _0), even if there is some change in the resistance pressure, ejection amount pump pressure P ₀ and the nozzle bore as shown in FIG. 8 Corresponding to the above, the ejection amount can be almost constant.

  Therefore, as shown in FIG. 9, according to the site ground conditions, a plurality of nozzle diameters, the number of nozzles, and the number of injection pipes can be provided, and a predetermined amount of air-containing liquid can be simultaneously supplied to each injection location. .

  In the present invention, a regulator (manufactured by Kosaku Giken Co., Ltd.) can be used in addition to the orifice (FIGS. 12 and 13). The regulator can control the pressure and flow rate on the downstream side corresponding to the pressure on the upstream side, and it can be installed in multiple pipes to control the pressure and flow rate at the same time. Regarded as a variable pressure type orifice, it is handled as a kind of orifice.

  Of course, in the present invention, even if the orifice is not used, the controller can operate only the branch valve by operating the branch valve to sequentially supply the material to the predetermined injection point (FIGS. 16 and 18). In this case, the discharge port at the tip of the injection tube is an orifice discharge port.

In FIGS. 16 to 18, by operating the branch valve without using an orifice, open V ₁ is injected treatment liquid only from V ₁ by closing the other, the other open V _i from V _i be closed Since the processing liquid is injected, the processing liquid can be continuously and selectively injected. In addition, if an orifice is used, simultaneous injection into all injection grounds becomes possible (FIGS. 19 and 20).

  In addition, a plurality of unit pumps and valves shown in FIGS. 21, 23, and 25 can be collectively managed by a controller, so that simultaneous supply or selective supply to a plurality of injection locations can be facilitated. In this case, the discharge port at the tip of the injection tube is an orifice discharge port.

  In FIG. 23, since the plurality of unit pumps are collectively controlled by the controller, the air-containing liquid can be simultaneously or selectively supplied to the plurality of predetermined injection locations at a predetermined discharge amount. In this case, the discharge port at the tip of the injection tube is an orifice discharge port.

  As the liquid feeding branch pipe or the liquid feeding pipe in the present invention, a plastic plastic tube having a diameter of about 0.5 to 2.0 cm, such as a symflex tube, can be used. Moreover, by using a biodegradation tube, it can be finally decomposed into water and carbon dioxide after the injection without collecting the injection tube.

  In order to know the degree of unsaturation, it is necessary to calculate from the absolute value of the air injected into the ground, but it was difficult to grasp the absolute value of the amount of air injected into the ground by the injected amount. This is because the gas pressure changes because the injection pressure in the injection ground changes during the injection. This is also the same for the liquid mixed with microbubbles, because the volume of microbubbles changes with the injection pressure.

When the present inventor ejects the gas-containing pressurized fluid from the pores provided at arbitrary positions in the flow path, the absolute amount of the ejected fluid is the differential pressure between the upstream pressure P ₀ and the downstream pressure P ₁ ( P ₀ -P ₁ ) and the hole diameter a of the injection port, and even if there is a certain change in the injection pressure P ₁ , it is found that the absolute amount hardly changes as long as there is a certain pressure difference ΔP. (See FIGS. 6 and 7).

  Therefore, the absolute amount of air can be managed by managing the pressure of the pressurized fluid and the hole diameter and number of the injection ports to predetermined values (FIGS. 8 and 9).

  Further, if a predetermined hole diameter and a number of injection ports (orifice discharge ports) are provided at the tip of the injection tube, even if the fluid in the pressurized fluid remains air, or a microbubble formed by a microbubble generator Even though the liquid supply pipe reaches the tip of the injection pipe, the pressure is released when it is injected into the ground, and is ejected as fine particles in the ground. It permeates and is retained between the particles (see FIGS. 10 to 13 and FIGS. 16 to 26).

  According to the present invention, if the amount of air can be measured without using a flow meter or pressure gauge and the amount of air injected into the ground can be managed, the degree of unsaturation can be grasped from the amount of air in the injection target region.

  That is, the discharge volume is grasped from the relationship between the pressure difference between the liquid feeding pressure from the pressurizing device for air-containing fluid such as microbubble liquid and the pressure in the injection pipe, and the pore diameter of the pores provided in the injection pipe. By grasping the amount of air injected into the interior, the degree of unsaturation can be estimated.

  In addition, even if microbubbles are gathered in the injection pipe, by micronizing the air-containing liquid at the tip of the injection pipe and injecting it into the ground, the microbubbles can be held between the soil particles in the ground, What is necessary is just to send a predetermined amount of air into the injection conduit and to inject it into fine particles in the ground.

  By increasing the number of pores or simultaneously injecting from multiple injection tubes, the pump pressure is excessively increased by performing a predetermined amount of injection through multiple injection tubes at the same time while performing a small amount of injection that does not deviate from the air. It is possible to increase the overall ejection amount without increasing the construction efficiency.

  Even if the soil can be desaturated by the above-mentioned method, depending on the ground conditions, the air may deviate over time or dissolve in water, and the degree of unsaturation may be reduced. The degree of unsaturation can be raised again.

(a) is an explanatory diagram when injecting air (bubbles) and injecting microbubble liquid in the conventional desaturation method, and (b) is when injecting microbubble liquid following the area where air is injected (C) is an explanatory view showing the behavior of normal bubbles and microbubbles. (a) is a table showing the relationship between the ground particles to be injected and the water permeability, and (b) is an explanatory diagram of the range of possible liquefaction in the case of sand with a large uniformity coefficient. (C) is explanatory drawing of the range with the possibility of liquefaction in the case of sand with a small uniformity coefficient. It is a graph which shows the relationship between the pressure and injection | pouring speed | velocity | rate of injection liquid, and the setting of a limit injection | pouring speed | rate. It is explanatory drawing of the characteristic of the simultaneous injection | pouring from the injection pressure which considered the Darcy rule, discharge amount, a water permeability coefficient, columnar penetration | infiltration, and several discharge holes. (a), is an explanatory diagram showing a relationship of (b) is liquid feed pressure (P ₀₎ and nozzle diameter (a) and ejection amount and soil penetration resistance pressure. It is a graph which shows the relationship between the ejection amount, the nozzle diameter, and the differential pressure (ΔP). It is a graph showing the relationship between osmotic resistance pressure (P ₁₎ and nozzle diameter (a) and ejection amount. Okueki圧(P ₀₎ and a graph showing the relationship between osmotic resistance pressure (P ₁₎ and the ejection amount. Okueki圧(P ₀₎ and nozzle diameter is a graph showing the ejection amount of the relationship between the number of nozzles. It is explanatory drawing which shows a microbubble generator and injection | pouring system. It is explanatory drawing which shows a microbubble generator and injection | pouring system (Equivalent injection | pouring of microbubble and air, or time difference injection | pouring is possible). It is explanatory drawing which shows the injection | pouring system which maintains the pressure of air-containing liquid at the stable constant pressure with a regulator. It is explanatory drawing which shows the injection | pouring system using a regulator. It is explanatory drawing which shows the injection | pouring system which can be simultaneously inject | poured from several discharge outlet. It is explanatory drawing of a flow volume and a pressure control apparatus. Explanatory drawing showing a system that allows continuous or selective injection to the outlets of a plurality of injection pipes via a branch valve (optimal injection corresponding to soil conditions from one microbubble generator) It is. It is explanatory drawing which shows the bundling injection | throwing-in-tubule injection | pouring tubule (it is provided with several pores in the front-end | tip part) which bound the some injection | pouring tubule. It is explanatory drawing which shows the system which inject | pours a microbubble containing liquid from several injection pipes through several branch valves from one injection pump. Continuous injection or selective injection is possible by opening and closing the branch valve. It is explanatory drawing which shows the system inject | poured through a several orifice from one injection pump through a several orifice, and a fine hole. It is explanatory drawing of the injection apparatus which inject | pours into a some injection | pouring pipe line simultaneously. In this case, the larger the pore diameter of the pores ground resistor pressure (P ₁₎ is directly pressure injection pipe (P _1), and the discharge amount of the ground from the injection tube and the P ₀ △ P (= P ₀₋ P ₁ ) and the orifice diameter. It is difficult to obtain a constant value for the air pressure (P ₀₀ ) of the compressor. For this reason, the pressure is reduced to a predetermined pressure (P ₀ ) by the regulator. The discharge amount from the injection pipe is increased by the resistance pressure (P ₁ ) of the ground, the pore diameter, the number of pores, and the reduced pressure (P ₀ ). The pressurized gas is atomized by the pores. It is explanatory drawing of the injection apparatus which inject | pours into a some injection | pouring pipe line simultaneously. A bundling injection capillary is provided in the ground, a consolidated layer is formed near the ground surface, and an air-containing liquid is injected into the lower part thereof to form an unsaturated layer. By providing the consolidated layer, escape of the air-containing liquid to the ground surface at the time of pouring can be prevented, and the unsaturated ground can be maintained by restraining bubbles over a long period of time. It is explanatory drawing in the case of bundling and inject | pouring simultaneously. In FIG. 21, when the air-mixed liquid is injected at the same injection point in the middle of injecting the solution-type solidified injection liquid, since the microbubbles in the air-mixed liquid have a particle size of 5 μm to 100 μm, the solution-type injection is performed. Since the permeability is lower than that of the liquid, the aerated liquid pushes the injected liquid that has not yet been gelled to the outside to form a spherical solidified layer, and holds the aerated liquid therein. In this case, the microbubbles are held inside the spherical consolidated layer and are not easily deviated to the outside, and the effect of maintaining the unsaturated ground is produced. It is explanatory drawing which shows the injection | pouring system which mixes microbubble simultaneously with inject | pouring injecting liquid from several unit pumps. It is explanatory drawing which shows injection | pouring from a bundling injection | pouring thin tube. It is explanatory drawing which shows the injection | pouring system which coat | covered the discharge port of the front-end | tip part of a bundling injection | pouring thin tube with the columnar osmosis | permeation source holding material, and enabled the osmosis | permeation at low pressure. Shows the structure of the columnar penetration source, (a), (b), (c) are elevations partially shown in cross section, (d) is an air-containing liquid that does not have a consolidation function deviates. It is explanatory drawing which shows osmosis | permeation holding | maintenance to a predetermined area | region, without. An injection tube with the function of injecting a solidified injection solution in part to prevent escape of air-containing liquid that does not have a consolidation function to the above-ground or rough layer and long-term escape was shown. It is a figure and you may use the injection tube which has a bag packer instead of a caustic injection solution It is the figure which showed the injection | pouring pipe | tube which coat | covers a bundling injection | pouring thin tube with a water-impermeable film, and inject | pours and inject | pours each injection-tube tip part out of a water-impermeable coating, and has the same effect as FIG. It is a schematic longitudinal cross-sectional view which shows the ground improvement construction method just under the existing structure. (a), (b) is a schematic plan view showing the ground improvement method directly under the existing structure. (a), (b) is a schematic longitudinal cross-sectional view which shows the ground improvement construction method just under the existing structure. The ground improvement method just under the existing structure is shown, (a) is a schematic plan view thereof, and (b) is a schematic longitudinal sectional view. The ground improvement method just under the existing structure is shown, (a) is a schematic plan view thereof, and (b) is a schematic longitudinal sectional view. (a) is a schematic plan view showing a ground improvement method for injecting an injection material into a plurality of injection points in the ground improvement region, and (b) is a plurality of injection points along a laying pipe (life line) such as a gas pipe. FIG. 2 is a schematic plan view showing a ground improvement method for injecting an injection material into (a), and FIG. (a), (b) is a longitudinal cross-sectional view which shows the ground improvement construction method which inject | pours an injection material into several injection | pouring points along laying pipes (lifeline), such as a gas pipe. (a), (b) is explanatory drawing of RI method which measures the content rate and density of the water | moisture content in the ground. (a) is a graph showing the relationship between saturation and dielectric constant in advance, (b) is a diagram showing the injection point, and (c) is construction management while simultaneously measuring multiple locations on site. It is a graph which shows the example.

Specific embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 (a) shows the concept of the conventional air injection method and the microbubble-containing liquid injection method, and FIG. 1 (b) shows the combined injection of air injection and microbubble liquid. Both can be implemented by the injection apparatus shown in FIGS. Fig. 1 (c) shows the characteristics of air mass and microbubble behavior in groundwater.

  Fig. 2 (a) is an explanatory diagram of the soil that is the target of ground injection, and Figs. 2 (b) and 2 (c) show the particle size distribution of the ground that tends to liquefy.

  FIG. 3 shows the relationship between the injection speed and the injection pressure for the injection solution to infiltrate between the soil particles, and shows the injection limit speed and the injection limit pressure for the infiltration between the soil particles.

  FIG. 4 shows Darcy's law in soil particle infiltration. In order to inject at the critical speed as shown in FIG. 3 under the ground conditions in FIG. 2, the injection speed must be reduced, particularly at the tip of the injection tube. Since the discharge speed is extremely small when injecting from the pores of the orifice or from the pores of the orifice, it is possible to inject from a plurality of injection pipes or a plurality of pores at the same time, or a columnar permeation having a large number of pores. By injecting through the source, it is possible to make the air infiltrate between the soil particles economically with a fine particle diameter.

5 to 9 show the nozzle nozzle diameter a and the upstream side when air or microbubble liquid is injected by the injection device of FIG. 16 using the air-containing liquid pressurization device of FIG. 10 or FIG. The relationship between the differential pressure ΔP between the pressure P ₀ and the downstream or ground resistance pressure P ₁ and the ejection amount is shown.

  The ejection amount referred to here is the discharge amount from the nozzle, and the nozzle is a fine hole (FIG. 10 (d)) provided in the injection tube injection unit, or the discharge port in the regulator of FIG. Or the orifice of FIG. 13, FIG. 14 is included.

Further, the upstream pressure P ₀ and the downstream pressure P ₁ here are the fluid pressure and the downstream pressure upstream of the pores or orifices.

FIG. 6 shows that the flow rate from one pore or orifice is such that the larger the differential pressure ΔP and the larger the pore diameter of the pore or orifice, the larger the ejection amount. Further, when the pressure on the downstream side increases and approaches the pressure on the upstream side, that is, when ΔP becomes a certain level (ΔP _b ) or less, the ejection amount becomes small and finally becomes zero.

FIG. 7 shows that when the upstream pressure P ₀ is constant, the injection amount increases as the nozzle diameter a increases, and the differential pressure ΔP between P ₀ and P ₁ even if the downstream pressure or the ground resistance pressure P ₁ varies. It can be seen that a certain amount of ejection can be obtained if is large to some extent. When the downstream pressure P ₁ becomes larger than a certain level and approaches P ₀ , the ejection amount approaches zero.

That is, in the air-mixed liquid, the volume of the air changes depending on the pressure according to Boyle's law or Boyle's law, so the volume changes if the resistance pressure P ₁ during the injection changes. Although it is difficult to grasp the absolute amount, if the differential pressure ΔP between the upstream pressure P ₀ and the downstream pressure P ₁ is sufficient, even if the injection pressure fluctuates during injection, the pressure does not change depending on the nozzle diameter. It can be seen that a certain amount of air is pumped into the ground.

Therefore, the relationship between P ₀ and P _{1 on} the ground and the range of ΔP in which a predetermined air-containing liquid is fed into the ground corresponding to the nozzle diameter are confirmed by test injection in advance, and the range of ΔP It is possible to grasp the amount of air-containing liquid injected into the ground without a flow meter by injecting in the ground, and therefore it is possible to grasp the unsaturation rate of the ground from the air content in the air-containing liquid, and design and construction It becomes extremely easy.

  If the pressure or temperature of the gas changes, the volume changes according to Boyle Charles' law. For this reason, the absolute amount of air cannot be managed with a flow meter used for normal chemical injection. Moreover, it is difficult to measure with an electromagnetic flow meter in a liquid mixed with air or bubbles.

By the way, when a fluid is passed through a nozzle having pores, a certain amount of fluid can be passed if the differential pressure ΔP between the upstream pressure P ₀ and the downstream pressure P ₁ is within a certain range.

When the downstream pressure P ₁ rises and approaches the upstream pressure P ₀ , that is, when it approaches ΔP ₀ , the flow rate gradually decreases. However, in the ground injection under the ground conditions of FIG. The limit injection speed for infiltration between soil particles is 1 to 6 liters / min for the linear range of FIG.

  For this reason, in FIGS. 9 and 13 to 21, if simultaneous injection is performed from a plurality of discharge ports at 1 to 6 liters / min per discharge port, it is possible to infiltrate between soil particles at a low pressure and a low discharge rate as a whole.

  For this reason, it becomes difficult for gas to escape to the ground surface. The diameter of the discharge port and the number of discharge ports may be determined so that injection per discharge port is performed under such injection conditions.

6 shows the relationship between the nozzle diameter a and ΔP and the discharge amount, FIG. 7 shows the relationship between the nozzle diameter and P ₁ and P ₀ and the ejection amount, and FIG. 8 shows the ejection pressure (pressure upstream of the nozzle) and the resistance pressure of the ground. FIG. 9 shows the relationship between P ₁ and P ₀ and the ejection amount in the case of the number of nozzles having a plurality of nozzle diameters.
In the case of the liquid supply pressure P ₀ , the ejection amount approaches zero as the ground resistance pressure P ₁ approaches P ₀ .

  By performing a test injection in advance and confirming these relationships, it is possible to inject within the limit injection pressure shown in Fig. 3 without measuring the injection flow rate and injection pressure one by one from all the injection tubes. It becomes possible to do. Of course, it is further measured with a flow meter and pressure gauge, or the orifice of the variable hole diameter orifice and the opening of the orifice are managed by a controller, such as opening / closing of a branch valve and a regulator (see FIGS. 13, 19, and 20). Therefore, arbitrary injection can be performed according to the ground conditions.

  As shown in FIGS. 13 to 26, the position of the ejection nozzle can be branched into a plurality of injection pipes via a plurality of ejection nozzles and injected into the ground at a predetermined discharge amount. ) To (d), FIG. 22, and FIG. 24 to FIG.

As an example in the case of injecting from a plurality of pipe lines, if the regulator is used, the pressure on the upstream side of the orifice is P _0i , and if the pore is sufficiently large, the pipe internal pressure and the ground on the downstream side of the orifice The resistance pressure is the same. The pressure on the downstream side of the orifice is P _1i , and ΔP _i = P _{0 i} −P _{1 i} . In this case, P _{1 i} can be regarded as a resistance pressure in the ground.

In FIG. 13, when there is no regulator, the liquid supply pressure upstream of the orifice is P ₀₀ and the pressure downstream of the orifice is P _1i , and ΔP _i = P ₀₀ −P _1i . If there is no regulator or orifice in FIG. 13, if the pore is small, the pore serves as an orifice (orifice discharge port), the liquid supply pressure upstream of the pore is P ₀ , and the ground resistance pressure is P ₁ . , ΔP = P ₀ −P ₁ . Thus, as described above, the air-containing liquid amount is calculated, whereby the air amount is calculated and the unsaturation rate can be calculated.

If there are any number of pores at the tip of the injection tube and the total area is larger than the cross-sectional area of the injection tube (non-orifice discharge port), the pores simply function as air subdivision.
When there is no orifice as described above, the pore diameter and number may be set so that the pore has the function of an orifice.

  FIGS. 10 (a) to (c) and FIGS. 11 (a) to (c) show an example of a micro-bubble (hereinafter referred to as “micro-bubble”) infusion solution generation apparatus used in the implementation of the ground improvement method of the present invention. In FIG. 10, reference numeral 1 denotes a microbubble generator (vortex generator) for mixing microbubbles into water or silica solution (hereinafter “injected liquid”), and reference numeral 2 denotes an injected liquid fed into the microbubble generator 1. A solution tank to be placed, and a reference numeral 3 is an injection tube for injecting the microbubble injection solution generated in the microbubble generator 1 into the ground.

  The microbubble generator 1 includes an impeller 1a that rotates at high speed by power (see FIG. 10 (c)), and a liquid feed pipe 4 extending from the solution tank 2 and an air supply pipe 5 for taking in air are connected to each other. In addition, a pressure feed pipe 6 extending to an injection pipe 3 for injecting a mixed solution of water or silica solution stirred and mixed and dissolved in the microbubble generator 1 and fine bubbles into the ground is connected. Further, valves 7 are respectively attached to the liquid feeding pipe 4, the air supply pipe 5 and the pressure feeding pipe 6.

  In such a configuration, the impeller 1a in the microbubble generator 1 is rotated at high speed by power, so that the injected liquid is sucked into the apparatus 1 from the solution tank 2 through the liquid feed pipe 4, and at the same time, the air supply pipe Air is sucked into the apparatus 1 through 5.

  The injection liquid and fine bubbles are stirred, mixed and dissolved by the impeller 1a rotating at high speed in the apparatus 1, and are pumped to the injection pipe 3 through the pressure feed pipe 6 and injected into the ground from the injection pipe 3. As a result, the ground is desaturated.

  As the microbubble liquid generator, for example, a microbubble liquid generator as illustrated in FIGS. 11A to 11C is also used. The microbubble liquid generator includes a microbubble generator 8, a feed water pump 9, and a compressor 10 (air may be self-supplied).

  The microbubble generator 8 includes a microbubble nozzle 11 including a circular passage 11a having a linear shape and a solution discharge passage 11b formed at the tip of the circular passage 11a and having an inner diameter larger than that of the circular passage 11a. An air supply pipe 5 extending from the compressor 10 is connected via a gas flow rate adjusting valve (valve) 7, and a water supply pipe 12 extending from the water supply pump 9 is connected to a side near the tip of the circular passage 11 a. The front end 12a of the water supply pipe 12 opens in the tangential direction of the inner peripheral surface of the circular passage 11a.

  In such a configuration, when the compressor 10 is operated, air is supplied to the circular passage 11a via the air supply pipe 5, and at the same time pressurized water is supplied from the water supply pump 9 to the circular passage 11a via the water supply pipe 12, A swirling flow of pressurized water and gas is formed by the flow of pressurized water in the solution discharge path 11b from the tip of the circular passage 11a. Then, microbubble water is discharged from the tip of the solution discharge path 11b. A silica solution mixed with microbubbles can be generated by supplying a silica solution under pressure instead of pressurized water to the circular passage 11a.

  If an excessive amount of air is sent from the air supply pipe 5, it becomes a supersaturated microbubble liquid, and air is also injected in the ground in addition to the microbubbles. That is, in the present invention, the microbubble liquid or the gas-containing liquid means a microbubble-containing liquid or a liquid in which microbubbles and air are mixed at the same time.

  In both cases, the microbubbles are adsorbed between the soil particles, but if the ground is constrained, air is easily held in the ground. Further, if the pressure of the pressurized water is increased, the dissolved amount of air can be increased. The melted air generated by generating a vortex in the nozzle portion is microbubbles and injected into the ground. However, not all of the air content in the microbubble-containing liquid is discharged as microbubbles in the ground. Since the microbubble generation rate in the ground differs depending on the pressure and air content of the injected microbubble-containing liquid, the pressure and temperature of groundwater in the ground, etc., calculation is performed in consideration of these conditions. Further, the dissolved amount of air in the produced microbubbles can be measured as described below.

  Examples of the injection device of the present invention are shown in FIGS.

FIG. 12 shows the simplest injection device. A constant pressure device using a compressor is difficult because it is not stable. However, there is no zero at the tip of the injection tube that pumps an air-containing liquid into the injection tube via a regulator. By providing an arbitrary number of pores of about 4 mm to 4 mm, the pressure difference ΔP (= P ₀ −P ₁ ) between the upstream side pressure P ₀ and the ground resistance pressure P ₁ with the pores as a boundary (if If there is no regulator, a discharge amount (per unit time) determined from the relationship between the differential pressure ΔP = P ₀₀ −P ₁ ), the pore diameter a and the number n is obtained (see FIG. 9). Even if P ₁ fluctuates, the discharge amount is almost constant (see FIG. 7), so a stable discharge amount can be obtained, and the amount of air injected into the ground can be found from the total discharge amount over the injection time, Therefore, the degree of unsaturation can be calculated.

Of course, if the resistance pressure P ₁ is large and approaches P ₀ , the discharge amount approaches zero, so P ₀ must be increased (see FIG. 9).
In this case, the air-containing pressurizing apparatus can also feed microbubble liquid or solidified silica bubbles to which a silica solution and a reactant are added.

  The regulator (pressure reducing valve, manufactured by Kosaku Giken Co., Ltd.) adjusts this unstable air pressure to an appropriate pressure because the compressed air sent out from the compressor is not very stable in terms of pressure. And serve to stabilize.

  Types of regulators and structural regulators are classified into direct acting (direct actuating) and pilot (indirect actuating) types.

[Direct acting regulator]
The valve is operated by the difference between the force of the pressure adjusting spring compressed by the handle and the secondary pressure acting on the upper side of the diaphragm to control the flow of compressed air from the primary side to the secondary side.

[Pilot type regulator]
A direct-acting regulator is incorporated as a pilot valve, and the regulator is operated with a secondary side air pressure to operate a larger regulator.

FIG. 20 shows an example of an injection device for injecting simultaneously into a plurality of injection pipes. The air-containing liquid is branched into a plurality of injection pipes and controlled to a predetermined pressure P _0n by the regulators, respectively. A predetermined injection amount is pumped in correspondence with the differential pressure ΔP _n between P _0n and P _1n . And even if the air-containing liquid that is pumped is agglomerated in it, it will be refined by the pores at the tip of the injection tube and injected into the ground as microbubbles and filled between soil particles become.

  In FIG. 14, the branch valve V is opened or closed simultaneously or selectively by the controller. Further, the pressure and flow rate of the compressor or pressurized microbubble generator can be controlled in accordance with the downstream pressure of the orifice and information from the flow meter. The orifice shown in FIG. 14 shows an orifice having a constant hole diameter, and a regulator or a flow pressure control valve (see FIG. 15) which is a hole diameter type or pressure capable type orifice can be used.

In FIG. 15, in accordance with an instruction from the control unit X, the injection solution from the injection solution pressurizing unit is sent to the flow rate pressure control valve via the injection pump. The control unit operates the reversible motor M of the flow rate / pressure control valve V _i of the flow rate / pressure control device U _i , and moves up and down by the forward / reverse rotation of the shaft 4 to control the flow rate / pressure control valve V _{i in} the control valve. The cross section of the flow path is controlled to have a predetermined flow rate.

For example, when the advanced by forward rotation of the shaft 4 (moved downward in FIG. 15), the cross section of the control valve in the flow path of the flow and pressure control valve V _i will flow becomes a small amount smaller, whereas the reverse rotation of the shaft 5 retracting by (moved upward in FIG. 15), the cross section of the control valve in the flow path of the flow and pressure control valve V _i is increased and the flow rate becomes large quantity.

In FIG. 16, a discharge port of an injection tube composed of a bundled injection thin tube is displaced in the axial direction, and a predetermined injection amount can be obtained depending on the diameter or number of pores at the tip of the injection thin tube. In this case, the diameter and number of the pores at the tip of the narrow tube are set so as to serve as an orifice. By increasing the number of capillaries in the bundle injection capillaries, the amount of discharge from one stage can be reduced, and a rough discharge amount as a whole can be obtained to achieve economical construction. Further, an orifice may be provided downstream of the branch valve. In this case, the pores at the tip of the injection capillary tube may simply have the function of subdividing the air-containing fluid into fine particles, so that the pore diameter and number may be arbitrary.
Therefore, the pores at the tip of the injection tube are different, and the former should also be referred to as orifice pores.

In addition, in this way, the discharge of the air amount from the discharge port or the horizontal discharge port to the plurality of soil layers in the depth direction is the water permeability coefficient of the ground, the porosity, the volume handled for the injection of the stage, every minute Since it can be set according to the discharge amount and total injection amount, it can be unsaturated without deviating because it can inject a small amount of air-containing liquid into the specified soil layer and carrying volume at the same time in small amounts at the same time in a wide range of injection target ground It can be turned into
Further, the injection tube and the injection device can be combined as shown in FIGS.
In addition, the infiltration layer of microbubbles can be stabilized by injecting a caking solution or fine particles into a predetermined layer to restrain the ground.

  Below, this invention shows the example of the construction method and construction management method of a microbubble liquid.

  17 (a) to (d) show an example of an injection tube inserted into the ground when carrying out the present invention. In particular, the injection tube shown in FIGS. 17 (a) and 17 (b) has a plurality of injection capillaries. 13 is formed by shifting the distal end discharge port 13a of each injection thin tube 13 by a certain length in the tube axis direction and binding them into one bundle.

  If the gas-containing liquid is jetted by squeezing the tip of the injection capillary tube, the gas in the injection tube becomes supersaturated and released into the ground, generating microbubbles and penetrating into the ground, and microscopically between the soil particles. Bubbles are easily adsorbed.

  By being configured in this way, the microbubble-mixed water and the silica solution are simultaneously applied to a plurality of stages (basement layers) having different depths from the distal end discharge ports 13a of the injection thin tubes 13 or one or a plurality of stages. The die can be arbitrarily selected and injected. It is also possible to inject a fine particle-containing injection material, a suspension injection material or a silica solution injection material into a shallow stage, and a microbubble solution into a deep stage. The fine particle-containing injection material or silica solution may contain microbubbles. Alternatively, the microbubble liquid may be secondarily injected by firstly injecting the fine particle-containing injection material or the suspension injection material. In addition, it is also possible to inject one of them in advance by using a plurality of injection tubes in combination with microbubble liquid injection and air injection (see FIG. 1 (b)).

  In this case, when the air injection is preceded, the air spreads groundwater in the ground to the surroundings, and the microbubble liquid is replaced before the groundwater returns to the original state, so that the microbubbles are adsorbed to the soil particles. For this reason, there is an effect that the microbubble liquid spreads over a wide range and the permeation range of the microbubble is widened. Using the apparatus of FIG. 11, the microbubble liquid and air injection can be equally injected as described above. In addition, after injecting the microbubble liquid using the injection pipe of FIG. 17, the air is injected from another injection pipe to spread the microbubble liquid to the periphery, or these steps can be repeated to permeate a wide range. it can.

  18 to 20 show an example in which an aerated fluid is pressurized and fed from one injection pump and simultaneously or selectively injected into a plurality of injection pipes via branch valves.

The pores in FIG. 18 are configured to serve as orifices.
In FIG. 19, the hydraulic pressure P ₀ in the injection pipe is determined by the regulator, and the amount of air injected into the ground is determined by the difference ΔP = P ₀ −P _{1 from} the ground resistance pressure P ₁ , the pore diameter and the number of pores. . In this case, the pore is configured to serve as an orifice.

FIG. 20 shows an example in which an orifice or a variable hole diameter type orifice (see FIG. 15) is used.
In this case, the amount of air injected is determined by ΔP = P ₀₀ −P ₁ and the area A of the orifice diameter opening of the orifice. In this case, the pores only need to have the function of atomizing the air in the injection tube.

  In FIG. 21, FIG. 22, and FIG. 25, water or silica solution mixed with microbubbles at a plurality of stages (basement layers) having different depths from the tip discharge port of each injection capillary tube at the same time or one or a plurality of stages. The die can be arbitrarily selected and injected. It is also possible to inject a fine particle-containing injection material, a suspension injection material or a silica solution injection material into a shallow stage, and a microbubble solution into a deep stage.

  The fine particle-containing injection material or silica-silica solution may contain microbubbles. Alternatively, a fine particle-containing injection material or a suspension injection material may be primarily injected, and a microbubble liquid may be secondary injected. Note that air can be injected from one of the plurality of injection tubes before or after the injection of the microbubble liquid. According to this method, the time-lapse deviation of microbubbles can be prevented over a long period of time.

  FIG. 23 and FIG. 24 show the side where microbubble liquid is injected simultaneously or selectively using a plurality of unit pumps. The tip of the injection tube is provided with a pore having an orifice function.

  In the apparatus of FIGS. 12, 13, 25, and 26, the injection tube device is attached so that a plurality of pores and the plurality of pores cover a certain range in the tube axis direction as shown in FIG. The injection apparatus which consists of a columnar penetration source which consists of a columnar space water conveyance member is shown.

  The injection tube device may be provided in a seal grout in the drilling hole. Since the air-containing liquid does not gel itself, there is a problem that it is difficult to enter a predetermined region unlike the injection of the consolidated liquid, and the air-containing liquid is easily deviated.

  In the present invention, the plurality of air-containing liquids discharged simultaneously from the discharge ports of the plurality of columnar permeation sources at a low discharge amount are unlikely to be mixed because the flowing liquid layers are repelled by each other's osmotic pressure. We focused on the horizontal penetration in the ground. For this reason, since the injection solution has a phenomenon that it penetrates in the horizontal direction without substantially escaping to the ground surface, it can penetrate at once in both the vertical and horizontal directions.

  Therefore, if the apparatus of the present invention is used, low-pressure injection capable of infiltrating between the pores can be performed, and the osmotic pressure of the adjacent injection solution is repelled and constrained and stratified infiltration. It is possible to continue to penetrate for a long time with a large discharge amount.

  Thus, in the present invention, it was found that if a plurality of stages permeate simultaneously, the flows are constrained by each other's osmotic pressure, so that permeation in the vertical direction is prevented and permeates in the horizontal direction. . The injection solution is injected by selecting the injection speed and the injection amount according to the state of the soil layer of each stage.

  By bundling a plurality of thin tubes so that the discharge ports are positioned at intervals in the axial direction, optimum injection can be simultaneously achieved for each of these layers even on the ground having a different ground condition. In addition, three-dimensional simultaneous injection in the vertical and horizontal directions in the ground is also possible (see FIG. 26).

27 and 28 show an example of an injection tube device used in the present invention.
Conventionally, in the case of injecting a solidified grout from a bundling injection tube 2A formed by bundling injection tubules 2a, if the bundling injection tubule 2A is installed in the seal grout 4 in the drilling hole, the injection tubule 2a of the bundling injection tubule 2A. No matter what the space is, there is no problem because the solidifying grout and the seal grout 4 in the drilling hole react to consolidate and close the space.

  However, since the air-containing fluid is non-solidified as described above, when the bundling injection thin tube 2A is used, even if the bundling injection thin tube 2A is installed in the seal grout 4, the gap between the injection thin tubes 2a is not sufficiently filled. Therefore, it is difficult for an air-containing liquid such as a microbubble liquid to flow out from the gap between the injection thin tubes 2a and be injected into a predetermined region. For this purpose, the following method is used.

(1) A method of filling the gap between the injection capillaries 2a not only in the drilling holes but also in the bundle injection capillaries with seal grout. For this purpose, a seal grout injection tube 21 is provided in the bundled injection thin tube to seal the gap (sea grout injection tube 21 in FIG. 27 (a)). The seal grout injection tube 21 may be removed together with the seal grout injection.

(2) A method in which a separator 30 is provided in a bundle injection capillary and installed in the seal grout 4 in the drilled ground (see FIGS. 27 (b) and (c)).

(3) A method in which a bundling injection tubule is provided in the seal grout 4 and a caustic grout is injected into at least the gap between the bundling injection tubules located above the air-containing liquid discharge port and the periphery thereof (FIG. 27 (a)). reference).

(4) A method (not shown) in which a bag is provided at least above the discharge port of the air-containing liquid in the bundling injection tubule, and the gap between the bundling injection tubules is injected by injecting a solidified material into the bag.

(5) A method (not shown) in which a plurality of bags are provided in (4) and grout is injected from an injection port provided between the bags.
(6) A method of wrapping the bundled injection tube with the bag body 9 and opening the injection / discharge port outside the bag body 9 (FIGS. 28A to 28C).

  In the present invention, it is suitable to form a target unsaturated ground by providing a partition wall on the ground to be injected and injecting the gas mixed liquid therein.

  The air-containing liquid tends to escape extensively in a plane along the boundary surface of the soil layer deposited in a plane in the deposition layer where liquefaction easily occurs. For this reason, it is effective to provide a partition wall in a predetermined range to prevent the escape of the mixed liquid, and then to desaturate the partition wall. This partition also has the effect of reducing shear stress due to earthquake motion.

  Further, when the air-containing liquid is injected into the ground through the injection tube, it is unclear whether the air-containing liquid has permeated to a predetermined range. That is, what is the degree of unsaturation in the reach of the air-containing liquid and in the injection area? And it is unclear how much to inject to complete the injection. In the desaturation method by air injection, it has been proposed to confirm the desaturation with a sensor such as a specific resistance method, but in this case, it is practically possible to grasp the desaturation of the entire planned ground improvement area. Have difficulty.

  However, by enclosing the improved region with a partition wall, grasping the gap amount of the liquefied layer inside it, calculating the target amount of desaturation air, and supplying the microbubble liquid in an amount that can be supplied by microbubbles. Management becomes easy by quantitative injection. In this case, by constraining the improved region with the partition walls, the gap amount of the liquefied layer can be accurately grasped, so that management is ensured.

  Furthermore, a ground improvement measurement sensor is installed at a predetermined position inside the partition wall, the saturation rate is measured over time, and the difference between the measured value and the calculated value of the degree of unsaturation by the target microbubble injection solution described above is determined. Therefore, it is possible to perform injection management and design for obtaining predetermined desaturation by grasping the injection rate of microbubble liquid, the content rate of microbubbles, the generation rate of microbubbles in the ground, or the loss rate.

  FIGS. 29 to 35 show the ground improvement method of the present invention performed as a countermeasure against liquefaction on the ground directly under an existing structure such as a storage tank. First, in the ground around the existing structure A, a mixture of fine particles such as suspended grout and white carbon, or a solution type silica grout or a solution type silica grout mixed with these fine particles. The partition wall 18 is formed by injecting. Alternatively, these may be primarily injected to fill the voids where the microbubbles can easily escape.

  Subsequently, a microbubble liquid is injected into the ground partitioned by the partition wall 18, or a fine particle mixed liquid or a silica solution (silica grout), or a solution in which a bubble liquid, air or microbubble is mixed in these solutions. By injecting, the ground directly under the existing structure can be desaturated to prevent liquefaction.

  The microbubble liquid may be injected after the fine particle mixed liquid or the silica solution is injected into the ground. As shown in FIG. 33 (b), silica grout mixed with silica grout or bubbles, air or microbubbles may be injected into the surface layer portion of the ground, and microbubble liquid may be injected into the lower layer portion. Further, water or silica solution mixed with microbubbles (air-dissolved solution containing bubbles of 5 μm to 100 μm) may be injected into the ground.

  The partition wall 18 is formed, for example, in the shape of a rectangular frame around the existing structure A so as to surround the ground directly under the structure, and the partition wall 18 is continuously formed up to the impermeable layer or non-liquefied layer 19. .

  Further, when the ground area in the partition wall 18 surrounding the existing structure A is considerably large, a grid-like partition wall 20 is formed inside the partition wall 18 as shown in FIG. Then, the ground in the partition wall 18 is divided into a plurality of parts (see FIGS. 31 to 34).

  The partition wall 18 is a steel sheet pile, concrete sheet pile, cast-in-place concrete wall, cast-in-place RC pile, continuous wall of high-pressure injection consolidated body or solid column (soil cement column), and suspension. Or it can also form by inject | pouring solidifying materials, such as a silica solution.

  By constructing in this way, injection materials such as fine particle mixed liquid, silica solution, or microbubbles are less likely to deviate to the surroundings, and are less susceptible to the influence of groundwater. Since deformation is less likely to occur, liquefaction is less likely to occur.

  Moreover, liquefaction can be prevented by injecting a microbubble solution to desaturate the ground. Therefore, even if a slight ground deformation is allowed and ground improvement does not lead to large liquefaction, an injection design within the allowable displacement according to the importance of the building on the surface (performance design) The ground can be improved economically.

  Further, by injecting water mixed with microbubbles or an injection material added with these fine particle liquid or silica solution into each board partitioned by the partition wall 20, seismic force is obtained due to the rigidity of the partition wall 18 and the partition wall 20. It is possible to reduce the shearing force caused by, and to reduce the shearing force acting on the inside to prevent liquefaction.

  In addition, since the liquefaction strength of the microbubbles is small, even if a slight displacement occurs during an earthquake, the liquefaction can be prevented by suppressing the overall ground displacement by the lattice-like partition wall 20, which is economical. It is possible to improve the ground by simple performance design, and it is possible to prevent the infusion of the microbubble injection liquid by the partition wall 18 and the partition wall 20, so that the liquefaction prevention effect by the microbubble can be maintained for a long time. it can.

  In addition, instead of the partition wall 18 and the partition wall 20, a plurality of columnar consolidated bodies (stakes formed with a soil mixture of soil cement and a consolidated material) are formed at regular intervals to form a consolidated body wall. After injecting fine particles around the columnar consolidated body, injecting microbubble liquid or silica bubble liquid mixed with fine bubbles to unsaturated the ground immediately under and around the existing structure and prevent liquefaction. be able to. In this case as well, ground improvement by performance design can be economically performed within a range that does not lead to large liquefaction even if a slight deformation of the ground is allowed.

  In FIG. 32, the ground liquefaction layer in the partition wall 18 and the ground improvement measurement sensor 21 are installed in the partition wall as shown in FIGS. By doing so, ground improvement can be performed very efficiently and reliably without waste.

  The ground improvement measurement sensor 21 is a soil moisture meter, an electrical resistivity measuring device, etc., and knows the extent of the change in the reach of the bubbles, the change in the degree of saturation, the decrease in the porosity, and the distribution status from the change in the electrical resistance or the dielectric constant of the ground. In this way, the administration of the injection can be performed.

  Further, as shown in FIGS. 33 (a) and 33 (b), the ground improvement measuring sensor 21, the injection pipe 22, the branch valve 23 connected to the injection pipe 22 and the pressure respectively installed in the drilling hole in the injection area. By centrally managing the meter 24, the flow meter 25, and the microbubble generator 26 by the controller 27, the injection amount, the selection of the injection pipe 22, the completion of the injection, the repetition of the injection, etc. based on the information from the ground improvement measurement sensor 21 Management can be performed.

  The injection amount of microbubble water required to obtain the target degree of unsaturation can be calculated from the porosity, the gap filling rate, the target unsaturation degree, and the air amount of the microbubbles contained in the injection liquid. In this manner, injection management and desaturation management can be performed.

  As described above with reference to FIGS. 29 to 33, the amount of air injected to obtain the amount of air necessary for the ground of the liquefied layer in the partition wall to be the target unsaturated ground is obtained from the injected amount of the microbubble injection solution. The amount of injected air is calculated. On the other hand, the degree of desaturation due to the injection, in which the amount of air in the microbubbles is calculated from the injection amount of the microbubble liquid injected from the predetermined injection tube, is calculated.

  Fig. 15 shows an embodiment of the injection system of Fig. 14; When using the orifices in the figure and when using the orifice discharge port, the hole diameter and the number of holes were set so that a predetermined aerated liquid could be injected.

  The diameter of the injection capillary having the orifice discharge port was 10 mm, the pore diameter was 1 mm, and four stages (n = 4), and a rubber sleeve or a bag (check valve) was put on the tip. The discharge amount per hole was 1 liter / min at a liquid feed pressure of 0.3 MPa, and 4 liter / min at 4 discharge ports. Further, an orifice having a hole diameter of 1 mm was provided under the branch valve, and the diameter of the non-orifice discharge port was 5 mm and 6 stages. In this case, the discharge rate from one injection tube was 1 liter / min, and 4 liters / min when discharged simultaneously from 4 narrow tubes.

  Since the amount of air in the air-containing liquid is known, the present invention can grasp the amount of air (or the amount of microbubbles) from the amount of air-containing liquid injected into the ground by the above method. Therefore, the degree of unsaturation of the ground can be estimated or the unsaturated ground can be designed by the following calculation.

1. Infusion improvement body design
1.1 [Basic formula]
The saturation Sr in the improved range can be expressed by the following formula.

here,
Improvement range V,
Porosity n,
Filling rate α,
Microbubble generation rate β,
Loss rate d,
Injection quantity Q
It is.

1.2 [Dissolution rate and formation rate of microbubbles]
The solubility of air is 0.019 cm ³ (19%) at 20 ° C. with respect to 1 cm ^{3 of} water per 1 atmosphere (0.1 MPa).
According to Henry's Law, the pressure and the dissolution rate are proportional. The microbubble dissolution rate δ with respect to 1 cm ³ of water when injected at 20 ° C. and P atmospheric pressure can be expressed by the following equation.

Further, when it is assumed that the injection liquid is atmospheric pressure when it is injected into the ground, the dissolved amount decreases to 0.019 cm ³ , and the difference is generated in the ground as microbubbles.
The microbubble generation rate β can be expressed by the following equation.

When injected at 2 atm (0.2 MPa), the microbubble dissolution rate δ is 38% and the generation rate is 19%.
However, the above difference does not always contribute to the generation of microbubbles. In that case, the microbubble generation rate may be added accordingly. Alternatively, the loss may be used as the loss rate.

1.3 [Examination of loss rate]
A ground having an improved range V of 1000 m ³ (10 m × 10 m × 10 m) and a porosity n of 0.4.
The amount of injection required to achieve 90% saturation is calculated.

If there is no loss rate (d = 0), 2104 m ³ may be injected.
Assuming that the loss rate is 10% (d = 0.1) in the above equation, 4208 m ³ injection is required.
This makes it possible to examine the injection amount in accordance with the loss rate. In addition, it is possible to design according to the actual ground by changing each parameter.
In FIG. 37 (b), the improved body is a sphere having a radius r (= 0.5 m). When the saturation Sr is 90%, the amount of bubbles q contained in the improved sphere is shown below.

When the injection speed is v, the generation speed of bubbles contained in water is v ′ = βv = 0.19v.
The time t required for 20.91 bubbles to enter at an injection rate v of 8 L / min is shown below.

  Although the degree of unsaturation can be calculated from the following injection of the air-containing liquid into the ground, the degree of unsaturation can be confirmed by actually measuring the amount of air in the injected liquid injected into the ground.

2. Method for measuring air content of microbubble liquid The air content of the microbubble liquid before being injected into the ground is measured.
This is a method of measuring the dissolution rate δ of microbubbles.

1) Calculation based on the pressure of the gas mixed in the injection solution 0.019 cm ³ (19%) of air is dissolved at 20 ° C. with respect to 1 cm ^{3 of} water per 1 atmosphere (0.1 MPa). According to Henry's law, injection pressure and solubility are in a proportional relationship. The solubility γ (%) when the pressure scale is x (atm) can be calculated by γ = 19 × x, and δ is calculated from this value.

2) Calculation from dissolved oxygen meter Yokogawa Electric Corporation (DO402G, DO70G, DO30G) is used as the dissolved oxygen meter.
The air contains about 20% oxygen. The amount of air can be calculated by multiplying the measured value by five.

When the saturation level of the ground is Sr, it can be represented by the amount of air β included in the ground gap β = (1−Sr) (%). The dissolved rate δ of microbubbles can be expressed as the sum of solubility and air amount β,
δ = β + 19 = (1−Sr + 19) = 2.9−Sr
It becomes.
Since the oxygen amount D ₀ is 20% of the dissolution rate δ, it is shown below.

Therefore,

When D ₀ indicates 40% (= 400 ppm), it can be determined that the saturation has reached 90%.

3) Measurement with a pycnometer Put water taken from the measurement port into the pycnometer. Seal to prevent gas from escaping. Water separates below and bubbles separate above. The amount of bubbles and the degree of saturation are calculated from the separation time, the diameter of the bubbles, and the position of the water surface using the Stokes formula.

  From the measuring instrument installed in the ground, it is possible to know the progress of the degree of unsaturation in the ground, the confirmation of the unsaturated region, and the completion of injection as follows.

  Moreover, the measurement of the degree of unsaturation of the ground can be used as a means for reinjection when the air deviates to the ground surface over time or when the degree of unsaturation is lowered by dissolving in the groundwater.

  According to the present invention, the degree of unsaturation can be set without directly measuring the degree of unsaturation in the ground as described above, but the degree of unsaturation in the injected ground is measured by the following method, and the ratio is more appropriate depending on the ratio. You may grasp the numerical value.

3. Measurement of air content in the ground This is a method for determining the microbubble generation rate β contained in the ground.
1) Measurement by electrical resistance (Fig. 37)
The degree of saturation is calculated from the measured dielectric constant to obtain the microbubble generation rate. The equation for calculating the degree of saturation is shown in Equation 1, and the equation for calculating the dielectric constant is shown in Equation 2. FIG. 37 (a) shows the relationship between Sr and K when Kair is 1, Kwater is 81, KsoiL is 4 and the porosity n and volumetric water content ratio θ are parameters. The saturation Sr is read from the measured value K.

Equations 1 and 2 are shown below.
[Formula 1]
Sr = θ / n × 100
[Formula 2]
K = (n−θ) Kair ^0.5 + θKwater ^0.5 + (1−n) KsoiL ^0.5

Sr: Saturation θ: Volumetric water content n: Porosity K: Dielectric constant Kair: Air dielectric constant Kwater: Water dielectric constant KsoiL: Soil dielectric constant

2) Measurement with soil moisture meter Volume moisture content θ can be obtained with soil moisture meter. The degree of saturation is calculated from the volume content.

  From these results, the loss rate can be converted to calculate the total injection amount.

4). Injection design example The ground having an improved range V of 1000 m ³ (10 m × 10 m × 10 m) and a porosity n of 0.4 is improved.
The target saturation is 90%, the loss rate d in the actual ground is 10%, and the saturation is 80%.

The solubility of air is 0.019 cm ³ (19%) at 20 ° C. with respect to 1 cm ^{3 of} water per 1 atmosphere (0.1 MPa). Since injection is performed at 2 atm (0.2 MPa), 0.038 cm ³ of microbubbles are dissolved at 20 ° C. per 1 cm ^{3 of} water (dissolution rate δ = 38%) according to Henry's law. When the injection solution is contained in the soil, it becomes atmospheric pressure (0.1 MPa), so that the dissolved amount is 0.019 cm ³ . 0.038cm ³ -0.019cm ³ = 0.019cm ³ is eluted, exists as bubbles in the soil (bubble content β = 19%).

The total amount of microbubbles injected into the improved body is shown below.

The total amount of injection into the improved body necessary for the presence of 80 m ³ microbubbles is shown below.

  If the injection interval is 1 m, 1000 improved balls can be formed. The injection amount per improved ball is shown below.

  The target injection time per improved ball is 60 minutes. The injection rate is shown below.

  Therefore, the ground was improved by using KTM32ND15Z (product of NIKUNI) as a microbubble generator (air turbo mixer) and injecting at a flow rate of 801 / min, a pressure of 0.2 MPa, and a motor power of 195 kW.

[Construction example]
Prior to injection, quality control was performed by installing sensors (TDR moisture meter (TDR-341F, Fujiwara Seisakusho)) at six locations shown in FIG. 37 (b). The saturation Sr can be calculated from the volume water content θ and the porosity n by the following formula.

The degree of saturation Sr is calculated from the displayed volumetric water content θ. For example, if θ shows 0.36, the target saturation is 90%.
The saturation was calculated from the volumetric water content, and the relationship between elapsed time and saturation was plotted.

  The result is shown in FIG. After 70 minutes, the saturation was 90% or less even at the farthest position from the measurement position, and it was confirmed that the predetermined quality was obtained by designing at 80% in consideration of the loss rate of 10%. In other improved bodies, it may be injected in 70 minutes.

  Therefore, after injecting air-containing liquid, measure the degree of unsaturation periodically to confirm that the value has decreased, and re-inject to maintain the specified degree of unsaturation. However, liquefaction can be prevented.

  In this case, the injection tube may be left in place and the injection may be performed over time, or the hole may be drilled again and the injection tube may be installed for injection.

  Of course, the degree of unsaturation may be measured and then reinjected. However, according to the present invention, the degree of unsaturation can be estimated from the amount of air in the injected liquid itself, so once the change in the degree of unsaturation over time can be confirmed. After that, a predetermined air-containing liquid may be injected at intervals of a predetermined period.

  For example, if it is understood that the degree of unsaturation is reduced to 20% to 10% after one year, it is sufficient to reinject after one year, and it is easy and inexpensive to inject the air-containing liquid. The value is immeasurable.

  In addition, desaturation by the groundwater lowering method is also known, but considering that there is a risk of damage to the structure due to consolidation settlement of the ground in this construction method, considering the cost of constantly pumping groundwater, the present invention Can understand the effectiveness of

  In addition, it is possible to estimate the reach of the injected liquid and the degree of saturation of the ground from the air content of groundwater collected by providing a water absorption pipe (or check hole, drain pipe) in the ground. Also, the degree of unsaturation of the ground is calculated from a sensor provided in the injection solution reach from the injection hole (see FIG. 33), and the degree of unsaturation calculated from the above injection solution and the measured value by the sensor The difference rate can be calculated by comparing the calculated degrees of desaturation.

  This difference rate is regarded as the loss rate of microbubbles in the ground, or the difference rate is used to generate the difference between the amount of air contained in the manufactured air-containing injection and the amount of air released in the ground. It can be considered as a rate, and the amount can be added and injected, or an injection design can be performed by increasing the microbubble mixing rate (pressurizing during microbubble production to increase the content of microbubbles, etc.). This is because the total amount of air in the air-containing liquid before being injected into the ground is not necessarily released into the ground. The above-described injection management can be performed by comparing and examining either one or both of the injection of the microbubble liquid per one and the injection of the entire injection region. The procedure is shown below.

  Further, as shown in FIG. 33, a ground improvement measurement sensor 21, an injection pipe 22, a water absorption pipe 28, a water absorption valve 29, a pressure gauge 24, respectively connected to the injection pipe 22 are installed in a drilling hole in the injection area. By centrally managing the flow meter 25, the microbubble generator 26, and the water absorption pump 30 connected to the injection pipe 22 by the controller 27, the injection amount, selection of the injection pipe 22 based on the information from the ground improvement measurement sensor 21, It is possible to manage the balance between groundwater level and groundwater pressure, such as completion of injection and repeated injection.

  In the injection of microbubbles, unlike the injection of the chemical solution, the injection tube 22 and the water absorption tube 28 do not have a risk of clogging after the injection because the injection solution does not solidify. When re-injection is necessary, the injection tube can be injected many times. Therefore, the upper portions of the injection pipe 22 and the water absorption pipe 28 are normally closed, and groundwater may be discharged through the check valve only when the pore water pressure increases during an earthquake.

  If this is done, dehydration compaction will not cause ground subsidence in normal times, and it will operate during an earthquake, so even if the function of microbubbles deteriorates after many years, the pore water will be dehydrated during the earthquake. The effect of preventing liquefaction by preventing an increase in water pressure is produced.

  Further, the invention of FIGS. 34 and 35 is a construction method, a construction management method, an infrastructure liquefaction prevention method, and particularly a line-shaped injection system and injection method.

  34 and 35 show a ground improvement method for injecting an injection material at a plurality of injection points simultaneously or by arbitrarily selecting one or a plurality of injection points, among which FIG. 34 (a) The ground where a single land is divided into multiple areas, and the injection material is injected at the same time or at any one or more injection points at the same time in areas where detached houses are built in each area. It is a top view which shows an improved construction method.

  FIG. 34 (b) shows a ground improvement method in which an injection material is injected through injection pipes at injection points set at regular intervals mainly along laying pipes (lifelines) such as gas pipes and water and sewage systems. FIG. 34 (c), FIG. 35 (a) and FIG. 35 (b) are schematic longitudinal sectional views of these.

In FIG. 34 (a), reference numerals X ₁ , X ₂ , X ₅ , X ₆ , X ₂ , X ₃ , X ₄ , X ₅ , X ₄ , X _n , X _i , X ₅ , X ₅ , X _6, X _7, X _i is stretches of land is divided into a plurality, and detached house a ₁ in each compartment, a _2, a _i, indicating the set injection point so as to surround the a _n.

In FIG. 34 (b), symbols X ₁ and X ₂ indicate injection points set at regular intervals along a laying pipe (life line) 33 such as a gas pipe or a water and sewage pipe. In FIG. 35 (a), L ₁ is a coarse sand layer and L ₂ is a fine sand layer, both of which are expected to be liquefied.

  As shown in the drawing, an injection tube 22 is inserted into each set injection point, and an injection material production plant 34, an injection pump, and a pressure / flow rate detector 35 are inserted into the injection tube 22 at each injection point via a liquid supply tube 36. Connect each one. These are collectively controlled by the controller 27 via the electric signal circuit 37, so that a plurality of injection points or one or a plurality of injection points can be arbitrarily selected to inject the injection material continuously.

More specifically, a flow path conversion electromagnetic valve 38 is installed in a liquid feed pipe 36 communicating with each injection pipe 22, and each flow path conversion electromagnetic valve 38 is collectively controlled by a controller 27. When an instruction is given from the controller 27 via the electric signal circuit 37 at a certain injection point, the flow path conversion electromagnetic valve 38 is activated, and the flow path conversion electromagnetic valve 38 at the injection point X _i is connected to the injection pipe 22 in the ground. Opens toward the injection point X _{i + 1,} and the flow path conversion electromagnetic valve 38 from the injection point X ₁ to X _i-1 opens only in the direction of the injection point X _i .

Then, when a predetermined injection amount is injected into the injection pipe 22 at the injection point X _i or when the injection pressure rises above the predetermined pressure, the flow path conversion electromagnetic valve 38 is similarly operated to supply the injection liquid to other injection points. The liquid can be fed, and the ground can be improved continuously by changing the injection point to a plurality of injection points. For example, when the flow path conversion electromagnetic valve 38 at a certain injection point is opened and the other flow path conversion electromagnetic valve 38 is closed, the injection liquid is injected into the ground only from the predetermined injection pipe 22.

  Of course, the flow path converting electromagnetic valve 38 may be configured to be operated manually, but if it is configured to operate when instructed through the electrical signal circuit 37 from the management center, even in a limited work space, Liquefaction measures can be implemented while using the lifeline.

  A plurality of ground displacement sensors 39 are arranged at predetermined positions, and the various ground displacement sensors 39 are collectively managed by the controller 27. Then, the ground displacement sensor 39 is used to monitor the controller 27 so as not to damage the ground structure or the underground buried object. When an abnormality is observed in the ground displacement at a certain injection point, the injection at the injection point is stopped. Therefore, the liquefaction prevention injection can be easily performed from around the structure by switching the injection to another injection point.

  Each flow path conversion electromagnetic valve 38 is a three-way cock, and is further equipped with a water washing tube. This is also managed by the controller 27, and when the injection from a predetermined three-way cock is completed, the water is immediately washed. The road can always be injected at a predetermined injection point.

  With the above configuration, according to the ground improvement method illustrated in FIG. 35 (a), liquefaction countermeasures are particularly effective and reliable in areas where a single land is divided into a plurality of areas and detached houses are built in each section. Can be done. Moreover, the liquefaction countermeasures for the entire detached residential area can be collectively performed, and the ground improvement of the entire residential area can be easily and economically performed.

  In addition, the ground can be improved without hindering the living environment of the residential area. In addition, although the liquefaction countermeasure of the residential area was explained here, it may be a continuous road or an airport runway, etc., and the injection line is formed by dividing the target to prevent liquefaction into several parts, A consolidated body may be continuously formed on the line. The injection line is a line of the liquid feeding pipe 36 that makes the injection pipes 22 continuous.

  On the other hand, according to the ground improvement method shown in FIG. 35 (b), laying pipes (lifelines) such as common grooves, subways, gas pipes, water and sewage pipes, cables such as telephone lines, or roads Measures for liquefaction of laying structures such as railways can be performed very efficiently and reliably.

FIGS. 35 (a) and 35 (b) show a solid column (soil cement or suspension) by injecting an injection material into injection points set at regular intervals along a laying pipe 33 such as a gas pipe or a water and sewage pipe. By forming a turbid grout or a column of silica solution-based injection material 40 and directly supporting the laying tube 33 on the consolidated column 40, damage such as non-uniform settlement of the laying tube 33 due to liquefaction is avoided. It is a thing. In the figure, reference numeral 41 is a seal grout, L ₁ is a coarse sand layer, and L ₂ is a fine sand layer, both of which are expected to be liquefied. Reference numeral 38 denotes a flow path converting electromagnetic valve.

In the figure, when the injection is continuously performed while sequentially moving the injection point to the injection points X _i−1 , X _i , X _{i + 1} ,..., The injection and the control plant 34 through the electric signal circuit 37 in three directions. The flow path converting electromagnetic valve 38 capable of converting the flow path is instructed to block the flow path to the injection pipe 22a of the three-way cock up to X _i-1 and release the flow path to X _i .

  In addition, it is desirable to form the consolidated column body 40 in each joint part (connection part) of the laying pipes 33 that are easily broken by liquefaction during an earthquake, and to support each joint part by the consolidated column body 40. Further, the liquid supply pipe 36 for supplying the injection material to the injection pipe 22 may be arranged in a zigzag manner with the laying pipe 33 interposed therebetween, or may be arranged on both sides of the laying pipe 33.

  In the laying pipes 33 thus subjected to the liquefaction countermeasure work, even if liquefaction occurs in the surrounding ground, the joint portions of the laying pipes 33 are supported by the consolidated column bodies 40, and the laying pipes 33 themselves By having a certain elasticity, a certain degree of deflection occurs but does not lead to destruction.

  The ground improvement method and the ground improvement device shown in FIGS. 21 and 22 are operated by independent drive sources 42 and controlled by a centralized management device 43, and the plurality of unit pumps 44 are A plurality of injection pipes 22 connected via the liquid supply pipe 36 and a microbubble generator 45 connected to each of the liquid supply pipes 36 disposed between each unit pump 44 and the injection pipe 22 are provided.

  The microbubble solution generated in the microbubble generator 45 by the operation of each unit pump 44 (for example, water mixed with fine bubbles or a mixture of fine bubbles and silica solution) is injected through the liquid feed pipe 38. It is pumped to the injection pipe 22 at the point and injected into the ground at each injection point via the injection pipe 22.

  In addition, each unit pump 44 is controlled by the centralized management device 43 so that the start, stop, restart, etc. of the bubble mixed liquid injection at each injection point can be arbitrarily controlled.

  FIG. 23, FIG. 24, and FIG. 25 show that the microbubble solution can be injected simultaneously or selectively into a plurality of injection points of the soft ground, and the optimum amount of microbubbles is applied to each layer having different ground conditions. Further, the escape of the microbubbles can be prevented by injecting the binder into the upper layer prior to the injection of the microbubbles.

  In addition, instead of the consolidated column body of FIG. 35 (b), a base body continuous along the laying pipe (life line) may be formed, and the life line may be supported by the base body. In this case, it is desirable that the consolidated column body is formed in the joint portion of the lifeline so as to support the joint portion. The position of the consolidated column body can be injected into the upper part or side surface of the laying pipe to prevent the pipe line from rising due to liquefaction.

  In addition, the injection pipe at each injection point may be installed perpendicular to the ground, may be installed obliquely under the foundation of a detached house, and may be used in combination with vertical installation and diagonal installation. Further, there may be a plurality of liquid supply paths to each injection point by the liquid supply pipe. Furthermore, the injection at each injection point is collectively controlled by the injection and management plant.

  Of course, even in the case of ground improvement over a wide area in a plane, the ground improvement can be continuously performed by combining the linear arrangement as shown in FIG. That is, the injection pipes shown in FIG. 17 are arranged at regular intervals along these facilities on the ground where the laying pipes 20 such as pipelines and water and sewage pipes are laid.

  In addition, by installing a flow path conversion electromagnetic valve and ground displacement sensor, a building or laying is performed by ground displacement due to pouring on a residential area where detached houses are densely populated, or a ground where gas pipes or water and sewage pipes are laid. The liquefaction prevention injection can be performed very simply and safely without breaking the object.

  Furthermore, injection pipes are arranged at regular intervals along laying pipes such as gas pipes and water and sewage pipes, and the respective injection pipes are connected by liquid feed pipes 13 arranged linearly along the laying pipes. By arranging the management plant 21, it is possible to inject a long section by using the minimum construction work range without moving the work point of the injection plant, so that the ground improvement can be performed while operating the lifeline. it can.

  Moreover, liquefaction can be prevented by injecting a microbubble solution to desaturate the ground. Therefore, even if a slight ground deformation is allowed and the ground is improved, the ground cannot be liquefied, so the ground can be improved extremely economically.

  Further, by injecting water mixed with microbubbles or an injection material added with these fine particle liquid or silica solution into each board partitioned by the partition wall 20, seismic force is obtained due to the rigidity of the partition wall 18 and the partition wall 20. It is possible to reduce the shearing force caused by, and to reduce the shearing force acting on the inside to prevent liquefaction.

  In addition, since the liquefaction strength of the microbubbles is small, even if a slight displacement occurs during an earthquake, the liquefaction can be prevented by suppressing the overall ground displacement by the lattice-like partition wall 20, which is economical. The ground can be improved, and the partition wall 18 and the partition wall 20 can prevent the microbubble injection liquid from being discharged, so that the effect of preventing the liquefaction caused by the microbubbles can be maintained for a long time.

  In addition, instead of the partition wall 18 and the partition wall 20, a plurality of columnar consolidated bodies (stakes formed with a soil mixture of soil cement and a consolidated material) are formed at regular intervals to form a consolidated body wall. After injecting fine particles around the columnar consolidated body, injecting microbubble liquid or silica bubble liquid mixed with fine bubbles to unsaturated the ground immediately under and around the existing structure and prevent liquefaction. be able to. In this case as well, the ground can be improved economically within a range that does not lead to a large liquefaction even if a slight deformation of the ground is allowed.

  In addition, if an injection tube made of a biodegradable resin is used as the injection capillary in the method of the present invention, it will be decomposed into carbon dioxide gas and water within six months to one year after construction, and within the living environment where the present invention is implemented. In this case, it becomes a liquefaction countermeasure work excellent in environmental conservation even if it is left after construction.

  The chemical structure of the biodegradable resin is as follows: (1) the main chain is aliphatic and has an ether bond or ester bond, and (2) the main chain (or side chain) has a hydroxyl group or a carboxyl group. Or (3) plastics with good biodegradability by containing additives that induce and promote photodegradation and microbial degradation of plastics, specifically starch-based, cellulose acetate-based, Examples include biodegradable plastics such as polylactic acid, aliphatic polyester, and polyvinyl alcohol. To these main raw materials, other polymer compounds such as plastics such as polyethylene and polypropylene, plasticizers, stabilizers, colorants and the like are added as necessary for the purpose of improving performance or imparting flexibility. You can also

  The compound (2) having a hydroxyl group or a carboxyl group is preferably an aliphatic compound. Specific examples of these biodegradable plastics include “Bionore” (aliphatic polyester of polyol and dicarboxylic acid) (Showa Polymer Co., Ltd. and Showa Denko Co., Ltd.), “Cell” Examples of “Green” (cellulose acetate, polycaprolactone) (Daicel Chemical Industries, Ltd.), “Lacty (lactic acid)” (Shimadzu Corporation), (2), “Poval” (polyvinyl alcohol) (Inc. Examples of (Kuraray) and (3) include “Wonder Starken” (corn starch and polyethylene) (Wonder Corporation) and the like.

  By blending the biodegradable plastics with high melting point biodegradable plastics such as polyhydroxybutyrate, polylactic acid, polyglycoside, etc., the processability is improved, and a woven fabric or non-woven fabric is used as a bag. Can also be used. These main raw materials are decomposed in the soil by bacteria for, for example, about 90 to 300 days.

The present invention makes it possible to economically improve the ground to prevent liquefaction due to desaturation by injecting an air-containing fluid such as microbubble liquid, and to easily perform injection design, injection management, and confirmation of the injection effect. those concerning the desaturation ground improvement equipment and methods.

Desaturation soil improvement apparatus of the present invention, the microbubble-containing liquid is injected through a plurality of injection tubes into the ground under the water table, a ground plate improved apparatus because turn into unsaturation ground, microbubble-containing liquid A pressure injection device for injecting a liquid, a liquid feed pipe, and an injection pipe, and a fine hole having a predetermined hole diameter and a predetermined number of holes is provided in the middle of the liquid supply pipe and the tip of the injection pipe. The orifice is formed by making the total area of the holes smaller than the cross-sectional area of the injection pipe, and the pressure injection device is adjusted so that the pressure in the liquid supply pipe on the upstream side of the orifice is higher than the ground penetration resistance pressure on the downstream side. By operating the microbubble-containing liquid on the upstream side of the orifice, the dissolved amount of air determined by the pressure difference between the pressure injection device and the ground penetration resistance pressure, and the pore diameter and number of pores is maintained. And from the plurality of pores to the tip of the injection tube The discharge port is provided that, it has to be injected into fine particles in the soil in which is fed to the injection tube a predetermined amount microbubble-containing liquid was kept air dissolved amount from the discharge port characterized in is there.

Further, the desaturated ground improvement method of the present invention is a ground improvement method in which a microbubble-containing liquid is injected into a ground under a groundwater surface through a plurality of injection pipes, and the ground is desaturated. A pressure injection device for injecting, a liquid supply pipe, and an injection pipe, and a pore having a predetermined hole diameter and a predetermined number of holes is provided in the middle of the liquid supply pipe and the tip of the injection pipe; Using an unsaturated ground improvement device in which an orifice is formed by making the total area of the injection tube smaller than the cross-sectional area of the injection tube, and a discharge port composed of a plurality of pores is provided at the tip of the injection tube. The pressure injection device is operated so that the pressure in the liquid feeding pipe on the side becomes higher than the ground penetration resistance pressure on the downstream side, and the pressure and the ground penetration resistance in the microbubble-containing liquid on the upstream side of the orifice The pressure differential pressure, and the pore diameter The microbubble-containing liquid in which the air-dissolved amount determined from the number is maintained and a predetermined amount of air-dissolved liquid sent into the injection tube is maintained is injected into the ground through the discharge port at the tip of the injection tube. It is characterized by this.

That is, in the present invention, the ground that prevents liquefaction by injecting the microbubble liquid into the ground below the groundwater surface through the injection pipe into the predetermined area of the ground where liquefaction is expected to desaturate the ground. In the improved construction method, a ground improvement device comprising a pressure injection device for injecting microbubble liquid, a liquid supply tube, and an injection tube is used, and pores having a predetermined pore diameter are provided at predetermined positions of the liquid supply tube and the injection tube. the provided by injecting infusate volume determined from the pore size of the injection pressure and the pores in the ground in the liquid feed pipe below the water table, it intends row desaturation of ground by the amount of air released into the ground (Fig. 2, FIG. 3, FIG. 4, FIG. 5).

Claims (7)

  A ground improvement device used in a ground improvement method for injecting an air-containing fluid through an injection pipe into the ground below the groundwater surface to desaturate the ground, and a pressurized injection device and a liquid feed pipe for injecting the air-containing fluid And an injection tube, provided with pores having a predetermined hole diameter and a predetermined number of holes at the tip or in the middle of the liquid supply tube and the injection tube, and the total area of the pores is smaller than the cross-sectional area of the injection tube Then, an orifice is formed, and the ground is not injected by injecting with the liquid feeding pressure in the liquid feeding pipe, the liquid feeding amount determined from the pore diameter and the number of holes, and the amount of air contained in the liquid feeding. Unsaturated ground improvement device characterized by performing saturation.   A ground improvement device for use in a ground improvement method for injecting an air-containing fluid through an injection pipe into the ground under the groundwater surface and desaturating the ground, a pressurized injection device for injecting the air-containing fluid and a plurality of injections A pipe, and distributing the air-containing fluid from the pressure injection device to the plurality of injection pipes, and providing pores at a plurality of locations of the injection pipe to the injection pipe tip of the injection pipe, An orifice is formed by making the total area of the pores smaller than the cross-sectional area of the injection tube, and the pores have a predetermined hole diameter and a predetermined number of holes so as to obtain a constant ejection amount. A desaturated ground improvement device, wherein the ground is desaturated by injecting the contained fluid into the ground.   3. The desaturated ground improvement device according to claim 1 or 2, wherein instead of the orifice formed by making the total area of the pores smaller than the cross-sectional area of the injection pipe, an orifice having a variable hole diameter or a variable pressure type An unsaturated ground improvement device, characterized in that an orifice is provided.   The desaturated ground improvement device according to any one of claims 1 to 3, wherein the injection tube is a plastic thin tube having a diameter of 1 mm to 10 mm, and an inner diameter of the injection tube is 0.4 to 4 mm. A desaturated ground improvement device characterized by comprising pores.   The desaturated ground improvement device according to any one of claims 1 to 4, wherein a discharge port composed of pores is provided at a tip portion of the injection tube, and contains a predetermined amount of air fed into the injection tube. A desaturated ground improvement device characterized in that a fluid can be injected into the ground as fine particles from the pores.   The desaturated ground improvement device according to any one of claims 1 to 4, wherein an orifice for adjusting a flow rate or a pressure is provided at a predetermined location from the pressurizing and injecting device to the injecting tube, and a tip of the injecting tube is provided. An unsaturated ground improvement device characterized by comprising a discharge port for a fine hole.   The desaturated ground improvement device according to any one of claims 1 to 6, wherein the injection pipe uses a plurality of injection pipes in which a plurality of the injection pipes are bundled at different positions in the axial direction to feed a predetermined amount of fluid into the ground. An unsaturated ground improvement device characterized by injecting.