JPS6342959B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for injecting silicate-based grout for ground stabilization using water glass as a main ingredient and carbon dioxide as a hardening agent, and its purpose is to improve the gel time of the grout injected into the ground. The object of the present invention is to provide a ground injection method that can be immediately changed to any length or shortness depending on soil conditions. The present inventors previously published Japanese Patent Application No. 51-150317 (Japanese Unexamined Patent Publication No. 51-150317) as a ground injection method for silicate-based grout using water glass as a main ingredient and carbon dioxide as a hardening agent.
74709), pressurized carbonated water is produced by contacting and absorbing high-pressure carbon dioxide gas in water in a closed container, and then the pressurized carbonated water is mixed in a line mixer (pipe mixing) while maintaining the pressurized state. We proposed a method in which the grout is mixed with a water glass solution in a container (container) and the grout thus obtained is injected into the ground. However, in this method, it usually takes several minutes or more to produce pressurized carbonated water with a predetermined concentration suitable for ground injection in a sealed container, so if this method is carried out continuously, The disadvantage is that the gel time of the injected grout cannot be immediately changed according to the soil conditions, so this method requires fine-grained ground stabilization work that corresponds to complex soil conditions. I can't. The present invention provides a continuous ground injection method for silicate grout using carbon dioxide as a hardening agent without such drawbacks. In a method of continuously injecting silicate-based grout into the ground using a hardening agent, a cylindrical sealed pressure-resistant container 1 is provided with a raw material supply port at one end and a pressurized carbonated water discharge port at the other end. It is a cylindrical rotating body that rotates with the central longitudinal direction of the pressure vessel 1 as its rotation axis, and a rotating body 2 having a large number of fluid mixing convex portions 3 provided on its outer peripheral surface is installed inside the rotary body 2, Water and carbon dioxide are continuously supplied to a raw material supply port of a mixer configured such that the gap between the outer surface of the section 3 and the inner peripheral surface of the pressure container 1 is 1/10 or less of the inner diameter of the pressure container 1. The pressurized carbonated water is then mixed in the mixer to produce pressurized carbonated water, and the resulting pressurized carbonated water is brought into contact with a water glass aqueous solution while maintaining the pressurized state.
A method for injecting silicate grout into the ground, which is characterized by injecting it into the ground while mixing. It's in 〓. In short, the present invention involves supplying carbon dioxide and water into a specific mixer, stirring and mixing them to produce pressurized carbonated water, and then mixing the obtained pressurized carbonated water with an aqueous water glass solution to infiltrate the ground. According to the present invention, pressurized carbonated water with a concentration suitable for grout injection into the ground can be produced in a very short time in the mixer. In the process of continuously injecting grout, the gel time of the grout can be changed to any desired length or shortness in a much shorter time (usually several seconds) than in the conventional method. The present invention will be explained below with reference to the drawings.
FIG. 1 is a longitudinal cross-sectional view of a mixer used in the present invention, and FIG. 2 is a cross-sectional view taken along the line AA' in FIG. In FIG. 1, 1 is a cylindrical sealed pressure-resistant container provided with a raw material supply port at one end and a pressurized carbonated water outlet at the other end, and 2 is a cylindrical rotating body housed inside the pressure-resistant container 1. The rotating body 2 rotates with the central longitudinal direction (line BB') of the pressure vessel 1 as the rotation axis. 4 is a raw material supply port, and 5 is a pressurized carbonated water discharge port. Although the raw material supply port 4 is installed above the cylindrical sealed pressure vessel 1 in the figure, it is not limited to this position only, and may be installed above the side of the pressure vessel. A convex portion 3 is provided on the outer circumferential surface of the rotating body 2 for mixing water and carbon dioxide supplied into the cylindrical closed pressure container 1 . Figure 3a is an enlarged view of the vicinity of the protrusion 3 in Figure 1.
(longitudinal sectional view) and FIG. 3b (transverse sectional view). In the mixer used in the present invention, a gap T between the outer surface of the convex portion 3 and the inner circumferential surface of the cylindrical sealed pressure container 1 is
(Fig. 3 a) is 1/1 of the inner diameter of the cylindrical sealed pressure vessel 1.
It must be less than or equal to 0. By setting the gap T to such a range, the water and carbon dioxide supplied into the cylindrical sealed pressure-resistant container 1 are finely divided by the shearing force of the convex portion 3 generated by the rotation of the rotating body 2, and are dispersed into the water. Carbon dioxide dissolves quickly. The height T' (FIG. 3a) of the convex portion 3 is not particularly stipulated, but it is usually preferably about 1 to 10 times, particularly about twice the height of the gap T. It is preferable to use a rotary body 2 with appropriate protrusions 3 formed on its outer circumferential surface so that the projected area of the protrusions 3 in the total surface area along the longitudinal direction of the rotor 2 is usually about 20 to 80%. , is preferable from the viewpoint of improving the mixing of the feed materials. In the figure, the convex part 3 has a rectangular cross section, but in the present invention, the convex part 3 is not limited to such a shape, and can be used to mix water and carbon dioxide well. It may be of any shape (for example, trapezoidal or arcuate) as long as possible. Furthermore, the shape of the outer circumferential surface of the rotating body 2, that is, the arrangement state of the convex portions 3, is not limited to that shown in FIGS. 1 and 2. It may have any shape as long as water and carbon dioxide can be mixed well. By changing the rotational speed of the rotating body 2,
Since the mixing state of water and carbon dioxide can be varied in various ways, it is desirable that the speed of the rotating body 2 is normally variable within a range of 50 to 5000 rpm. In the present invention, water and carbon dioxide are supplied to the mixer configured in this way, and by stirring and mixing, pressurized carbonated water with a concentration suitable for ground injection is usually produced in a few seconds to more than ten seconds. It can be manufactured in a short time. Next, an embodiment of the present invention will be described using FIG. 5. In FIG. 5, 6 is a carbon dioxide storage tank, 7 is a water storage tank, and 8 is a water glass solution storage tank. As the carbon dioxide storage tank 6, a commercially available liquefied carbon dioxide cylinder can be used. In the present invention, both carbon dioxide gas and liquefied carbon dioxide gas can be used as carbon dioxide, and when carbon dioxide gas is used as a carbon dioxide source in the present invention, the liquefied carbon dioxide gas cylinder is held upright as shown in FIG. Install it so that carbon dioxide gas can be taken out from the outlet. On the other hand, when extracting liquefied carbon dioxide from this cylinder, install the cylinder upside down so that the outlet faces downward. In addition, since liquefied carbon dioxide gas cylinders are also commercially available which are equipped with a siphon tube inside so that liquefied carbon dioxide gas can be taken out even when the cylinder is installed with the outlet facing upward, in the present invention, such a cylinder may be used as appropriate. A cylinder can also be used as the carbon dioxide storage tank 6. An embodiment in which carbon dioxide gas is used as a carbon dioxide source in the present invention will be described. Carbon dioxide gas is continuously pumped from a carbon dioxide storage tank 6 to a raw material supply port of a mixer 9. The flow rate of carbon dioxide gas is controlled by a flow control valve 6'. Meanwhile, at the same time, water is continuously pumped from the water storage tank 7 to the raw material supply port of the mixer 9 using a metering pump 7'. The mixer 9 simultaneously pumps each raw material to the mixer 9.
Rotates the rotating body built inside. The raw materials fed under pressure into the mixer 9 are quickly mixed by the mixing action of the rotating body to produce pressurized carbonated water. The rate of absorption and dissolution of carbon dioxide into the water glass aqueous solution is accelerated as the pressure increases, so in the present invention it is necessary to increase the pressure of the feedstock to increase the pressure inside the mixer 9. Usually mixer 9
The pressure inside is set at several kg/cm ² to several tens of kg/cm ² (gauge pressure), and the higher the pressure, the more highly concentrated pressurized carbonated water can be produced. Next, the pressurized carbonated water produced in this way is discharged from the pressurized carbonated water outlet while maintaining the pressurized state and mixed with the water glass aqueous solution. The air bubbles (CO ₂
It is also possible to connect a gas-liquid separator or the like to remove gas). In the present invention, to mix the pressurized carbonated water and the water glass aqueous solution, any mixing equipment commonly used for mixing this type of chemical solution is used. Examples include Y-shaped pipes, pipe mixers for mixing two liquids, and double-pipe rods for chemical injection that are used for normal ground injection and have a mixing chamber between the lower end of the inner pipe and the grout outlet. However, from the viewpoint of ease of maintenance, a so-called static pipe mixer or a Y-shaped pipe, in which an element (stirring mixer) having no moving parts is installed inside the pipe, is preferably used. Figure 5 shows a Y-tube 1 as such a mixer.
0 is shown as an example. It is desirable that the pressurized carbonated water and the water glass aqueous solution are supplied to the Y-tube 10 at approximately the same pressure. If the supply pressure of either one of the liquids is too high, the other liquid may flow backwards, making it impossible to mix the two. In addition, in order to prevent such backflow, it is preferable to provide a check valve at the inlet of the Y-shaped pipe 10. The pressurized carbonated water and the water glass aqueous solution supplied into the Y-tube 10 are mixed while maintaining the pressurized state within the pipe, so the water glass and CO ₂ react quickly and the grout is prepared. Next, the grout mixed in the Y-tube 10 is injected into the ground by a pump. The gel time of the grout is normally adjusted by varying the amount of carbon dioxide supplied to the mixer 9 or by varying the concentration of the water glass aqueous solution supplied to the Y-tube 10. . Generally, when preparing a grout with an extremely short gel time, it is preferable to supply a large amount of carbon dioxide to the mixer 9, increase the rotational speed of the rotating body 2, and increase the pressure inside the mixer. Next, the present invention will be explained using examples. Example: Inner diameter with a built-in cylindrical rotating body with a diameter of 45 mm and a length of 98 mm with numerous fluid mixing convex parts on the outer circumferential surface
A stainless steel cylindrical sealed pressure-resistant container measuring 47 mm and 130 mm in length was prepared. While rotating the rotating body, water and carbon dioxide were continuously supplied separately from the raw material supply port provided at the upper end of the pressure container. Both raw materials supplied into the pressure container were homogeneously mixed within a short time (6 to 12 seconds, see Table 1) to produce pressurized carbonated water. Next, the obtained pressurized carbonated water was supplied from the pressurized carbonated water outlet to one entrance of the Y-tube using a metering pump, and at the same time, JIS No. 3 sodium silicate was supplied to the other entrance of the Y-tube using a pump. Note that the supply pressure of sodium silicate and that of pressurized carbonated water were approximately equal. A pressure-holding valve was provided at the outlet of the Y-tube to maintain the pressure inside the pipe. Both raw materials supplied to the Y-shaped tube are mixed within the tube and discharged from the outlet. Next, the grout discharged from the Y-shaped pipe was injected into river sand through an injection pipe and hardened. After curing, the unconfined compressive strength of the resulting sand gel was measured. The experimental conditions and the results obtained are shown in Table 1.

[Table] As is clear from Table 1, in the present invention, pressurized carbonated water is produced in an extremely short time in a sealed pressure-resistant container. The gel time of the grout can be changed to a longer or shorter time within a certain period of time. The rotating body used in this example has the same shape as the rotating bodies shown in FIGS. 1, 2, 3a, and 3b, and the dimensions of the convex portion are as follows. As shown. a=b=2mm, T=1mm, T'=2mm, H=4mm, H'=2mm

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the mixer used in the present invention, Fig. 2 is a cross-sectional view taken along the line A-A' in Fig. 1, Fig. 3 a is an enlarged view of the vicinity of the convex portion 3 in Fig. 1, 3b is a cross-sectional view taken along line A-A' in FIG. 3a, FIG. 4a is a vertical cross-sectional view of the rotating body 2 used in the present invention, and FIG. The line cross-sectional view, FIG. 5, represents a flow sheet representing one embodiment of the present invention. 1... Cylindrical sealed pressure container, 2... Rotating body, 3
... Convex portion, 4 ... Raw material supply port, 4' ... Raw material supply port, 5 ... Pressurized carbonated water outlet, 6 ... Carbon dioxide storage tank, 6' ... Flow rate control valve, 7 ... Water storage tank ,7'...
... Metering pump, 8... Water glass storage tank, 8'... Metering pump, 9... Mixer, 9'... Metering pump,
10...Y-shaped pipe, 11...grout injection pipe, T...
...Gap between the outer surface of the convex part 3 and the cylindrical hermetically sealed pressure vessel 1, T'...Height of the convex part 3, H...Width of the convex part 3 (rotational axis direction), H'... Interval (direction of rotational axis), a... Width of convex portion 3 (direction perpendicular to rotational direction),
b... Distance between convex parts 3 (direction perpendicular to the rotation axis)

Claims (1)

[Claims] 1. A method of continuously injecting a silicate-based grout for ground stabilization using a water glass aqueous solution as a main ingredient and carbon dioxide as a hardening agent into the ground, with a raw material supply port at one end and a material supply port at the other end. A cylindrical rotary body that rotates with the central longitudinal direction of the pressure vessel 1 as its axis of rotation is placed inside a cylindrical sealed pressure vessel 1 provided with a pressurized carbonated water outlet, and a large number of fluids are mixed on the outer circumferential surface thereof. A rotating body 2 provided with a convex portion 3 for mixing is installed inside, and a gap between the outer surface of the convex portion 3 for fluid mixing and the inner peripheral surface of the pressure vessel 1 is 1/10 or less of the inner diameter of the pressure vessel 1. Water and carbon dioxide are fed under pressure to the raw material supply port of a mixer configured as above, and the two are mixed in the mixer to produce pressurized carbonated water.Then, the obtained pressurized carbonated water is put into a pressurized state. A method for injecting silicate grout into the ground, which is characterized by injecting it into the ground while contacting and mixing water glass while maintaining the . 2. The ground injection method according to claim 1, wherein the carbon dioxide is carbon dioxide gas. 3. The ground injection method according to claim 1, wherein the carbon dioxide is liquefied carbon dioxide.