JP2745224B2 - Ground improvement method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a ground improvement technique, and particularly to a technique for combining liquefied carbon dioxide with other grout components while maintaining its liquid state. A method of mixing carbon dioxide and water to obtain carbonated water, and then bringing it into contact with a material that reacts with the carbonated water, for example, water glass, and injecting it into the ground from an outlet of an injection pipe to stabilize the ground, and a method for stabilizing the ground. Related to the device.

[Conventional technology]

As a grout injection method of this type, in the past, one liquid grout was injected, but after that, it was improved and each liquid of two liquid hardening grout was injected into a Y-shaped pipe provided at the base end of the injection pipe. After that, instead of the method of combining the two liquids, the mainstream now is to combine the two liquids inside or outside the injection pipe, mix them, and then inject them into the surrounding ground.

Various types of two-component curable grout are known, but water glass (sodium silicate) is currently the mainstream in that it does not contaminate the ground. For the water glass, the reactants include acids and acid salts.

On the other hand, a method of stabilizing the mixture by injecting a mixed solution thereof into the ground using carbonated water as a reactant for water glass is known, for example, from JP-A-53-74709.

Carbon dioxide has the essential advantages of being inexpensive and harmless.However, when carbon dioxide is absorbed into water to produce carbonated water and this carbonated water is reacted with water glass, how to produce carbonated water However, only a part of the method has been put into practical use, and it is urgently necessary to establish a method for the method.

 This reaction is represented by the following equation.

2H ⁺ + CO ₃ ^2- + Na ₂ O · nSiO ₂ → Na ₂ CO ₃ + H ₂ O + nSiO ₂ ↓… (1) Na ₂ O · nSiO ₂ + 2H ₂ CO ₃ nSiO ₂ + 2NaHCO ₃ + H ₂ O… (2) Therefore, carbonic acid When water and water glass are mixed and injected, silica and sodium carbonate are generated in the ground, and a weak portion in the ground can be strengthened.

When producing carbonated water, the present inventors disclosed in Japanese Patent Application Laid-Open Nos. 62-228516 and 63-11712 that water was sprayed while filling a gaseous carbon dioxide gas in a packed reaction tower. While producing carbonated water by spraying,
It has been disclosed that a vaporizer is provided between the cylinder and the packed reaction tower so that the liquefied carbon dioxide from the cylinder is sufficiently vaporized at the stage of entering the packed reaction tower even in winter.

[Problems to be solved by the invention]

Although carbonated water can be produced with the equipment described in the above publication, a large packed reaction tower is required to produce carbonated water corresponding to the injection amount, and the amount of carbon dioxide supplied to the tower and the amount of water are increased. Unless the supply amount is properly controlled for the level of carbonated water (liquid level) in the tower in accordance with the amount of injection, the carbonic acid concentration in carbonated water will fluctuate greatly, and materials that react with carbonated water, such as water glass, will be used. Is not stable, and a compact having a required strength may not be obtained.

Further, when carbon dioxide is a gas, the accuracy error of the flow control valve for adjusting the supply amount to the packed reaction tower is relatively large,
The difficulty of accurate flow control also makes the above problem more apparent.

Therefore, a main object of the present invention is to continuously produce carbonated water of a constant concentration without requiring difficult or delicate control,
It is an object of the present invention to provide an improved method and apparatus for improving the ground that can be easily manufactured, can stably obtain a consolidated body having a required strength, and can reduce the size of equipment.

[Means for solving the problem]

The method of the present invention for solving the above-mentioned problems is characterized in that carbon dioxide is mixed with water in a liquid state, and then injected into the ground while being brought into contact with a material that reacts with the carbon dioxide.

Further, the first apparatus according to the present invention includes a first confluence of liquefied carbon dioxide and water, a second confluence of generated carbonated water and a material reacting therewith, At least one pressure-holding valve is provided between the junction and the second junction and holds the liquefied carbon dioxide at a predetermined pressure or higher to keep the liquefied carbon dioxide in a liquid state.

Further, the second device includes a first confluence of the liquefied carbon dioxide and water, a second confluence of the generated carbonated water and a material reacting therewith, and a second confluence of the liquefied carbon dioxide and the first confluence or the second confluence. At least one pressure-holding valve disposed between the first junction and the liquefied carbon dioxide source, the liquefied carbon dioxide being disposed between the first junction and the liquefied carbon dioxide source; Liquid holding means for adjusting the temperature of the carbon dioxide and holding the liquid state at least up to the position where the pressure holding valve is provided.

Further, the third device is disposed between the confluence of the liquefied carbon dioxide and other grout components reacting with the liquefied carbon dioxide, and a predetermined pressure for maintaining the liquefied carbon dioxide in a liquid state. A pressure holding valve that holds the above, liquid holding means that is disposed between the pressure holding valve and the liquefied carbon dioxide source, adjusts the temperature of the liquefied carbon dioxide, and holds the liquid state at least up to the pressure holding valve arrangement position. It is characterized by having.

[Action]

The main point of the present invention is to combine and contact liquefied carbon dioxide with other grout components in the middle of the injection route while maintaining the liquefied state of the liquefied carbon dioxide.

For example, in producing carbonated water, instead of contacting gaseous carbon dioxide and water to produce carbonated water,
Liquid carbon dioxide is brought into contact with water in a liquid state to produce carbonated water of a required concentration. Therefore, the mixing properties of liquefied carbon dioxide and water are extremely excellent because they are merged in the same liquid state, and the amount of liquefied carbon dioxide and the amount of water up to the confluence can be easily controlled, and the liquefaction By changing the amount of water with respect to the amount of carbon dioxide, the concentration of carbonated water can be easily and quickly changed, thereby changing the reactivity with materials that react with carbon dioxide, such as water glass, and a grout with a desired gel time. Can be easily obtained. Therefore, the present invention can be effectively used for a so-called compound injection method in which the gel time is sequentially changed between instantaneous setting and slow setting.

On the other hand, because of the excellent mixability of liquefied carbon dioxide and water,
In joining them, reliable mixing can be achieved only by using a simple T-shaped or Y-shaped tube, and therefore,
Unlike the conventional case, it is possible to prevent the equipment from becoming large by providing a large packed reaction tower, and it is not necessary to delicately control the liquid level of the tower, and it is possible to reduce the equipment cost.

Furthermore, when liquefied carbon dioxide is mixed and mixed with other grout components, for example, water or water glass, if carbon dioxide is a gas, the gas flow is dominant and the mixing property is extremely poor, so the carbon dioxide is in a liquid state. Although it is necessary, it is very effective to provide a pressure-holding valve to keep the liquid at least up to the junction. Whether the carbon dioxide is a liquid or a gas can be understood from its vapor-liquid equilibrium diagram. In order to keep carbon dioxide in a liquid state, it is not practical from the economical point of view to keep a long distance of the pipe line to the junction point cool. Also, even if it is kept cool, the considerably high pressure of liquefied carbon dioxide itself acts on the junction, and the mixing property is extremely poor due to a large imbalance with the feeding pressure of other grout components.

Therefore, according to the present invention, if a pressure-holding valve is provided and maintained at a pressure at which a liquid is maintained at least up to the pressure-holding valve, the liquid state of carbon dioxide can be easily maintained, and it is practical and more practical. Since the pressure can be reduced on the downstream side of the pressure valve, the mixture with other grout components is excellent.

In this case, when the liquid holding means by temperature control according to the present invention is used in combination, the liquid holding property becomes more excellent.

[Specific configuration of the invention]

 Hereinafter, the present invention will be described in more detail.

FIG. 1 is a schematic view of the apparatus of the present invention. 1 is a cylinder as a source of liquefied carbon dioxide, and liquefied carbon dioxide flowing out of the cylinder is shown in FIG.
The CO ₂ (1) is guided by the first pump 3 to the first junction 5 via the first pressure holding valve 4 while being kept cool by the refrigerator 2 as the liquid holding means of the present invention. On the other hand, the water W is supplied from the storage tank 6 to the first junction 5 by the second pump 7.
At the first junction 5, it is contacted and mixed with liquefied carbon dioxide to form carbonated water CW, and the second junction 8
It is led to. The water glass NS in the storage tank 9 is guided to the second junction 8 by the third pump 10, and at the second junction 8, the carbonated water CW and the water glass NS are joined and mixed,
The grout G is injected into the surrounding ground through the injection pipe 11 having the second pressure holding valve 12.

FIG. 2 shows a more specific embodiment of the apparatus. In this embodiment, the pumps 3, 7, and 10 are connected by a crankshaft 20 and driven by one drive motor 21. 22 and 23 are transmissions. The transmission 23 is a pump 3
Adjust the rotational speed of the side crankshaft by adjusting its handle
It has the same function as that of the conventional flow rate control valve for adjusting the amount of liquefied carbon dioxide to the junction 5 by adjusting the flow rate at 23a. 24 is a filter, 25 is a flow meter and flow control means.

The portion denoted by reference numeral 2 'is a low-temperature chamber which is cooled by the refrigerator 2 and is kept in a liquid state so that liquefied carbon dioxide is not gasified even in summer. Its liquid temperature is -20 ℃
~ + 10 ° C is preferred.

The first pressure holding valve 4 keeps the pressure of liquefied carbon dioxide up to this point high, preferably 30 to 60 kg / cm ^2.
-It is for maintaining a pressure of G (gauge pressure, the same applies hereinafter) and keeping it in a liquid state.

Now, referring also to FIG. 3 to FIG. 5 showing a detailed structural example of the injection pipe 11, the above-mentioned carbonated water CW and water glass NS are:
Through a swivel (not shown), a known double pipe structure connecting pipe is used to reach the injection pipe tip device shown in FIG.

In this portion, various members described below are provided in the outer tube elements 20A to 20E.

That is, on the base end side, the protrusion 30, the meson 31, the connector 32,
The tail 33 is screwed and connected. Carbonated water
First, the CW enters the first path a1 at the center of the projection 30 and passes through a plurality of second paths a2 formed obliquely in the radial direction from the end thereof.
A plurality of fourth paths that pass through the third path a3 in the gap between the outer periphery of the projection 30 and the inner surface of the outer tube element 20A and that extend obliquely toward the center from the end.
After passing through a4, it enters the fifth path a5 at the center of the meson 31, and the third pressure holding valve 41 urged by the spring 34 having the tail 33 as a seat.
While pushing down, the vehicle reaches the sixth road a6 in the tail child 33.

On the other hand, the water glass NS includes the outer periphery of the projection 30 and the outer tube element 20A.
From the first path b1 having a gap between the second path b1 and the second path b2 penetrating the protrusion 30 in parallel with the axis, the third path b at the center of the tip of the protrusion 30
And, while pushing down the check valve 43 urged by the spring 35 having the meson 31 as a seat, penetrates through the thick portion of the meson 31 in parallel with the axis from the fourth path b4 inside the meson 31. Through a plurality of fifth paths b5, a sixth path b6, which is a gap between the outer circumference of the meson 31, the connector 32, and the tail 33, and the inner surfaces of the outer pipe elements 20A, 20B, is reached.

Reference numeral 36 denotes a lock nut. After determining the urging force of the spring 34 by rotating the tail 33 around the central axis in order to determine the operating pressure of the third pressure holding valve 41, the tail 33 is moved to the connector 32. Is fixed. 37 is a guide seat for the spring 35.

On the other hand, a mixing promoting body 50 is provided at the front end of the tail 33, and a valve seat 61 of the second pressure-holding valve 42 is provided at the front end. The second pressure holding valve 42 is urged toward the valve seat 61 by a spring 64 having a spring seat 63 locked and fixed via a lock nut 62 with respect to the outer pipe element 20C.

The mixing promoting body 50 is disposed substantially in close contact with the inner surface of the outer tube element 20B, and has a substantially columnar shape with a length of about 25 cm, for example. A groove is formed on the outer peripheral surface of the mixing promoting body 50, and a path for returning from the base end side to the front end side and returning to the base end side so as to flow backward once or more, in the embodiment, about 5 reciprocations. Road
51 are formed. In addition, finally, one outward groove is added in order to face the tip of the injection pipe. Thus, the liquid passes through (25 × 5 × 2 + 25) grooves totaling about 275 cm in length.

Generally, the length of the mixing promoting path is preferably 0.5 m, more preferably 1 m or more.

Now, as described above, the first to sixth paths a6 of the carbonated water CM,
The first to sixth paths b6 of the water glass NS are formed independently up to the tip of the tail 33, but the carbonated water CW and the water glass NS
After passing through the distal end face of the tail 33, when it tries to enter the mixing promoting passage 51 from the inlet concave portion 52A at the base end of the mixing promoting body 50, the mixing and contact mixing is performed for the first time. Thereafter, these mixed materials are sufficiently mixed with sufficient reaction time and mixing time in the course of passing through the long mixing promotion path 51 at a flow rate, and become a mixed grout.
From the valve seat 61, and is injected into the ground from the injection port 70 at the tip of the injection pipe 11 through the grout passages g1 to g5.

3 and 4, the mixing accelerator 50
The cross-sectional shape of FIG. 2 is shown as a shape of only two reciprocating paths and one outward path for simplification of the drawing.

As described above, when the mixing promoting body 50 having the reciprocating mixing promoting path 51 is internally provided, a residence time many times longer than the length of the mixing promoting body 50 can be taken, so that the mixing reaction is sufficiently performed. As a result, the carbonated water CW and the water glass NS are not injected into the ground while being separated. In the case of two-component curable grouts other than this type, it is not necessary to pay much attention to mixing if they are merged, but in view of the poor mixing property between carbonated water and water glass, The adoption of the means shows effectiveness.

On the other hand, if the miscibility handle bad carbonated water and water glass, not only achieve an increase in reaction time, the pressure in the mixing portion relatively high pressure or 1 kg / cm ² G or more, preferably 3 kg / cm ² G It is important to mix and react while maintaining the pressure at 5 kg / cm ² G or more, more preferably.

For this purpose, in the present embodiment, a third pressure holding valve 41 and a second pressure holding valve 42 are provided on the base end side and the tip end side of the mixing promoting body 50. That is, in order to maintain the inside of the mixing promotion passage 51 at a relatively high pressure, the pressure of the third pressure holding valve 41 should be 5 kg / cm ² G or more, preferably,
Supply carbonated water at about 10 kg / cm ² G or more, particularly about 15 kg / cm ² G or more and about 40 kg / cm ² G or less, and the operating pressure of the second pressure holding valve 42 is 1 kg / cm ² G or more, preferably 3 kg / cm ² G or more. cm ² G or more, especially 5 kg / cm
² G or more.

Thereby, the pressure in the mixing section is maintained at the operating pressure of the second pressure holding valve. The check valve 43 is operated when the dynamic pressure acts on the water glass NS. The supply pressure of the water glass is 1.5 to 10 kg / cm ² G, preferably 3 to 10 kg / cm ² G.
It is 7 kg / cm ² G.

A general check valve operates as long as the dynamic pressure acts, but as in the present embodiment, in order to maintain the mixing promoting portion between the pressure holding valves 41 and 42 at a high pressure, a pressure holding valve 41 is used. , 42 is considered to be the first step in grouting.

Instead of the mixing accelerator 50 in the above embodiment, a mixing accelerator 50 'having a spiral mixing accelerator 51' as shown in FIG. 6 may be used. In this example, the head passes through every other spiral groove toward the distal end, goes from the reversing portion 53 ′ to the proximal end through the other every other spiral groove, enters the center path 54 ′ at the proximal end, and enters the distal end 55 ′. It is made to get out of.

On the other hand, as a structural example of the junction 5 of the liquefied carbon dioxide and the water W, as shown in FIG.
By adjusting the pressure through the liquefied carbon dioxide, the one that adjusts the pressure of the liquefied carbon dioxide can be preferably used.

In the above example, if the pump pressure of the water W is set to be substantially the same as the pressure of the liquefied carbon dioxide, the third pressure holding valve 41 can be used as the “pressure holding valve” according to the present invention, and the first pressure holding valve 4 is installed. Can also be omitted. Therefore, at least one of the pressure holding valves 4 and 41 may be present. A plurality of pressure holding valves 4 or 41 may be provided.

On the other hand, after the liquefied carbon dioxide and the water glass are first brought into contact and mixed, the mixture may be injected as it is or after being combined with water and diluted.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, according to the present invention, excellent mixing and mixing properties of carbon dioxide and other grout components are achieved, and stable mixing and mixing can be performed without requiring difficult control. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of the apparatus of the present invention, FIG. 2 is a schematic view of a specific apparatus, FIG.
6 are explanatory views of a mixing promoting body installed inside the injection pipe, and FIG. 7 is a cross-sectional view of a structural example of a pressure holding valve according to the present invention. 1 ... liquefied carbon dioxide cylinder, 2 ... refrigerator (liquid holding means), 3, 7, 10 ... pump, 4 ... (first) pressure holding valve, 5,
8 ... Confluence point, CW ... Carbonated water, W ... Water, NS ... Water glass, 11 ... Injection pipe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoichi Kashima 1-10-3 Hiroo, Shibuya-ku, Tokyo Inside Hasebu No. 3 Building Nippon Soil Industry Co., Ltd. (72) Inventor Takehiko 4-chome Sendagaya, Shibuya-ku, Tokyo No. 20-3 Japan Integrated Waterproofing Co., Ltd. (72) Inventor Mineo Murata 5-30-2 Kamimeguro, Meguro-ku, Tokyo Yamaguchi Machinery Co., Ltd. (72) Inventor Shunsuke Tazawa Oguro, Tsurumi-ku, Yokohama, Kanagawa Prefecture 10-1 Machito, Nitto Chemical Industry Co., Ltd. Central Research Laboratory (72) Inventor Akira Horiba 1-5-1 Marunouchi, Chiyoda-ku, Tokyo Nitto Chemical Industry Co., Ltd. (72) Inventor Koji Ishida 1 Marunouchi, Chiyoda-ku, Tokyo Chome 5-1 Nitto Chemical Industry Co., Ltd.

Claims (4)

(57) [Claims] 1. A method for improving ground, comprising mixing carbon dioxide in a liquid state with water, and then injecting it into the ground while being brought into contact with the material reacting with the carbon dioxide. 2. A first junction between liquefied carbon dioxide and water, a second junction between the produced carbonated water and a material reacting therewith,
And at least one pressure-holding valve disposed between the liquefied carbon dioxide and the first junction or the second junction and holding the liquefied carbon dioxide at a predetermined pressure or higher to keep the liquefied carbon dioxide in a liquid state. Ground improvement equipment. 3. A first junction between liquefied carbon dioxide and water, a second junction between the produced carbonated water and a material reacting therewith,
At least one pressure-holding valve disposed between the liquefied carbon dioxide and the first junction or the second junction and holding the liquefied carbon dioxide at a predetermined pressure or higher to keep the liquefied carbon dioxide in a liquid state; and A liquid holding means arranged between the liquefied carbon dioxide source and a liquid holding means for adjusting the temperature of the liquefied carbon dioxide and holding the liquid state at least up to the position where the pressure holding valve is provided. . 4. A convergence point between liquefied carbon dioxide and another grout component reacting with the liquefied carbon dioxide, which is disposed between the convergence point and the carbon dioxide source, and maintained at a predetermined pressure or higher to keep the liquefied carbon dioxide in a liquid state. And a liquid holding means disposed between the pressure holding valve and the liquefied carbon dioxide source for adjusting the temperature of the liquefied carbon dioxide and holding the liquid state at least up to the pressure holding valve disposition position. A ground improvement device, characterized in that: