JPH0236154B2 - JIBANCHUNYUZAIOYOBIJIBANNOANTEIKAHOHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a ground injection agent and a ground stabilization method. BACKGROUND ART Conventionally, chemical injection methods have been known in which various chemical solutions (ground injection agents) are injected into the ground and gelled in the ground in order to strengthen soft ground or stop spring water from flowing into the ground. One of the chemical injection methods is the penetration injection method. In this construction method, a ground injection agent with a gel time of several minutes to several tens of minutes is injected into the ground, and after the ground injection agent sufficiently penetrates into the gaps between soil particles, it is gelled. However, in this penetrating injection method, a ground injection agent with a gel time of several minutes or more is injected into the ground. However, there are drawbacks such as making the construction work uncertain, and the possibility that the ground injection agent may flow into groundwater or well water, causing pollution problems. In recent years, the instant bonding method has been developed as a construction method that eliminates the drawbacks of the penetration injection method. This construction method is a construction method in which a ground injection agent injected into the ground gels in the ground within a short period of several seconds to more than ten seconds. Ground injection agents developed for the instant bonding method include, for example, ground injection agents containing as active ingredients an aqueous sodium silicate solution as a base agent and an acidic liquid such as a mineral acid aqueous solution or an acidic mineral salt aqueous solution as a hardening agent. It has been known. However, when the ground is stabilized by the instant setting method using such known ground injection agents, the strength of the stabilized soil is insufficient, and when excavating the treated soil, it is difficult to stabilize the ground. The disadvantage is that the soil may collapse. In order to eliminate these drawbacks, attempts have been made to stabilize the soil by using a composition in which aggregates such as clay, diatomaceous earth, calcium carbonate, and gypsum are added to the above-mentioned ground injection agent. The strength of the treated soil is still insufficient. In view of the current situation, the inventor of the present invention has conducted intensive research to develop a desired ground injection agent suitable for the instant bonding method, and has finally completed the present invention. That is, the present invention provides a ground injection agent containing a sodium silicate aqueous solution and an acidic liquid as main components, which is characterized by containing amorphous silicon dioxide in addition to the main components, and a sodium silicate aqueous solution and an acidic liquid. In the grouting method, liquids are separately injected into the ground, and they come into contact with each other in the ground and gel.
The present invention relates to a method for stabilizing ground, which comprises adding amorphous silicon dioxide to the aqueous sodium silicate solution and/or acidic liquid. By using the ground injection agent of the present invention, the strength of treated soil can be significantly improved compared to that of soil treated with conventional ground injection agents. One component constituting the composition of the present invention is an aqueous sodium silicate solution. As the sodium silicate, a wide variety of conventionally known ones can be used, and examples thereof include No. 1, No. 2, and No. 3 specified in JIS K-1408. In the present invention, sodium silicate is used in the form of an aqueous solution. The concentration of sodium silicate in the sodium silicate aqueous solution is not particularly limited and can be appropriately selected from a wide range, but is usually 25 to 75% (V/V), preferably
It is best to set it at 40-60%. If the concentration of sodium silicate is too low, only an agar-like gel can be obtained by reaction with a hardening agent, and even by stabilization treatment, it tends to be difficult to obtain soil with sufficiently improved strength. Furthermore, if the concentration of sodium silicate is too high, the viscosity of the aqueous sodium silicate solution will not only become difficult to handle (penetrate into the soil), but also the mixing with the curing agent will not be carried out well, resulting in the gel being obtained. A tendency towards non-uniformity arises. Another component constituting the composition of the present invention is an acidic liquid. As the acidic liquid, a wide variety of conventionally known ones can be used, such as aqueous solutions of mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and aqueous solutions of acidic mineral salts such as acidic sodium sulfate and acidic sodium phosphate. The concentration of the curing agent component in the acidic liquid varies depending on the type of mineral acid or acidic mineral salt, the concentration of the sodium silicate aqueous solution, etc., but it cannot be generalized, but the gel time of the ground injection agent of the present invention is about 10
It is preferable that the concentration be within seconds and at a level that can impart sufficient strength to the stabilized soil. The ratio of the sodium silicate aqueous solution and the acidic liquid to be used is not particularly limited and can be appropriately selected from a wide range.
It is usually advisable to use the latter in a volume 0.5 to 2 times that of the former, preferably about the same volume. Another component constituting the composition of the present invention is amorphous silicon dioxide. The amorphous silicon dioxide may be either natural or synthetic, and is preferably in the form of fine powder with a specific surface area of 50 m ² /g or more and a particle size of 20 μ or less, such as synthetic hydrated silicic acid called white carbon. . The amount of amorphous silicon dioxide to be used is not particularly limited and can be appropriately selected within a wide range, but it is usually about 0.5 to 20% (W/V) based on the total amount of the above sodium silicate aqueous solution and acidic liquid, preferably about 0.5 to 20% (W/V), preferably It is best to use about 1.0 to 15%. If the amount of amorphous silicon dioxide used is too small, it will be difficult to achieve the desired effect of the present invention, and if it is too large, the viscosity of the ground injection agent will increase rapidly, resulting in poor workability during soil stabilization treatment. This is not preferable because it reduces the A gelling aid may also be added to the ground injection agent of the present invention. As gelling aids, a wide variety of gelling agents known in this field can be used, such as magnesium sulfate, aluminum sulfate (sulfate band), potassium aluminum sulfate (potash alum), calcium chloride,
Examples include magnesium chloride and other polyvalent metal salts. The amount of such gelling aid used is usually 5% (W/V) or less, preferably 0.5 to 3% (W/V) based on the total amount of the sodium silicate aqueous solution and the acidic liquid.
% (W/V). By adding the gelation aid, the gel time can be further shortened and the strength of the stabilized soil can be further improved. When using the ground injection agent of the present invention, each component may be individually mixed in the same manner as the conventional ground injection agent for instant bonding methods. For example, it is preferable to separately prepare a sodium silicate aqueous solution with a concentration suitable for ground stabilization and a desired acidic solution in dedicated tanks before construction, and then inject both into the ground during construction. At this time, a predetermined amount of amorphous silicon dioxide may be blended into either or both of the sodium silicate aqueous solution and the acidic liquid before being injected into the ground. The ground injection agent of the present invention may be prepared by injecting each of the ingredients of the injection agent into the ground and allowing these ingredients to gel in the ground. As the method for injecting the ground injection agent into the ground, conventionally known methods can be widely applied. For example, a hollow double pipe with an appropriate rod attached to its tip (soil injection part) is driven into the ground, a silicic acid aqueous solution and an acidic solution are poured into the tube separately, and these are immediately injected into the ground from the rod at the tip. A method can be adopted. The time required for gelation is usually within about 10 seconds, preferably about 2 to 5 seconds. Examples are given below. Example JIS No. 3 Sodium silicate 100% was diluted by adding 100% water to obtain a sodium silicate aqueous solution. Add this to liquid A (main ingredient)
That's what it means. On the other hand, various mineral acids and acidic mineral salts [95% sulfuric acid, 85
% phosphoric acid and acidic mirabilite (39% as H ₂ SO ₄ )],
Water was added to the predetermined amounts of potash alum and white carbon (trademark Carplex #67, manufactured by Shionogi & Co., Ltd.) shown in Table 1 below to make the total amount 200. This is called liquid B (curing agent). After adjusting the temperature of liquid A and liquid B to 5° C., the two liquids were mixed in equal proportions and transferred to a 50φ×50 vinyl chloride mold to prepare a specimen. After curing this at 5° C. for 60 minutes, the unconfined compressive strength was measured. The results are shown in Table 1.

[Table] When blending 11.0 kg of 95% sulfuric acid, the unconfined compressive strength (Kg/cm ² ) when using 10 kg of talc instead of white carbon and 20 kg of talc is only 0.71 and 0.85, respectively. First, in all cases, the strength was weaker than when amorphous silicon dioxide was used.

Claims (1)

[Scope of Claims] 1. A ground injection agent containing a sodium silicate aqueous solution and an acidic liquid as main components, characterized in that it contains amorphous silicon dioxide in addition to the main components. 2. A grouting method in which a sodium silicate aqueous solution and an acidic liquid are separately injected into the ground and brought into contact and gelled in the ground, characterized in that amorphous silicon dioxide is added to the sodium silicate aqueous solution and/or the acidic liquid. Ground stabilization method.