JPH07111050B2 - Ground injection method using cement grout - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground injection method for injecting a plurality of grouts having different setting times into an earth through an injection pipe to consolidate the ground or to stop the water, and in particular, the use of the grout is regulated. By using cement grout without using chemicals such as water glass, which is pollution-free and permanent, the soil can be consolidated or stopped evenly, and the single pipe rod is used as an injection pipe, which is economical. And a ground pouring method using cement grout with improved workability.

[0002]

2. Description of the Related Art Conventionally, a soft or leaky ground has been made uniform,
Moreover, as a method of solidifying or stopping the water firmly, a ground injection method using an injection pipe rod is known.

By the way, in the case of the injection method using a chemical solution, the chemical solution flowed into the well water during the sewerage work in Fukuoka Prefecture in 1974, which caused health problems for residents.
The Ministry of Construction issued the “Temporary Guideline for Construction Work by the Chemical Injection Method” (hereinafter abbreviated as “Temporary Guideline”) on July 10, 1974, and it is still required to comply with this regulation.

The conventional ground injection method using the injection pipe rod is divided into four types: a one-shot system, a 1.5-shot system, a two-shot system (double-pipe strainer single-phase type), and a double-pipe strainer multi-phase type. being classified.

(1) One-shot method The one-shot method is a method of pumping one type of grout with a single pump and injecting it into the ground. The gelling time of the grout is long, generally several tens of minutes or more. A single tube is used for the rod. Considering that the idea of the grout method is to infiltrate the grout into the soil particles and replace the pore water with the grout to consolidate it, by using the grout with a long gelation time, the ground to be injected becomes more homogeneous. Caking is possible, and this point is superior to the 1.5-shot method. However, even if it is attempted to infiltrate the suspended particles of cement grout into the soil particle gap by only the one-shot method, in many cases, cement grout easily flows out along the injection pipe rod to the surface of the earth, and permeability It's hard to say good grout. In addition, if the ground to be injected is coarse soil, or if the groundwater flow is large, etc., if it is attempted to treat it only with grout having a long gelation time, the grout will move and will be scattered or diluted in the distance. In many cases, the desired effect cannot be obtained.

(2) 1.5-shot method The 1.5-shot method is based on the main agent and curing agent or the A liquid and B
The solution is stirred by separate mixers, pumped individually to each, and then joined with a Y-tube or water swivel attached to the top of the injection tube rod to inject it into the ground. A single tube is used as the injection tube rod because the mixing of the both liquids is performed in the injection tube rod in units of about several minutes.

In the 1.5-shot method using cement grout and cement quick-hardening material, (A) When the groundwater is injected into a large ground, it is possible to prevent the grout from being diluted or moved by the groundwater. (B) When injected into the ground consisting of multiple strata, the grout can be prevented from being washed away through the highly permeable stratum. There are advantages such as. However, even with the 1.5-shot method, when water glass is used as a rapid hardening material for cement grout, and when the gelling time is approximately 1 minute or more, this injection material can be easily applied along the injection tube rod. Spilled to the surface,
Furthermore, solution-type grout cannot be expected because it is washed away with groundwater. Homogeneous infiltration is not possible with the 1.5-shot cement suspension type grout, and the shape of the solidified body tends to be lens-like or vein-like. The 1.5-shot method is one means for restricting the rough gap and the flow of groundwater except for special cases such as filling of cavities, and even if the injection is continued more than necessary, the ground is rather opened. It only exacerbates such as lifting.

(3) Two-shot method The two-shot method is also called as a double-tube strainer single-phase type, and the gelling time of the grout is shorter than that of the 1.5-shot method and is generally within 30 seconds. Is performed immediately before or immediately after it is discharged to the ground, and each grout must be kept separately in the injection pipe rod, and a multiple pipe is used for the injection pipe rod.

A chemical solution is used in the two-shot grout, and when the chemical solution is used, the provisional guideline by the notification of the Ministry of Construction is applied.

Therefore, according to this provisional guideline, for example, "Chapter 2 Selection of chemical injection method 2-1 Selection of chemical injection method" Adoption of selection of chemical injection method is conducted by conducting the survey mentioned in 2-2 in advance. As a result of examining the suitability of other construction methods for areas where ground improvement is required, unless the chemical injection method is used, work security, protection of underground buried objects, maintenance of surrounding houses and other works, and It shall be limited to the case where it is recognized that it is extremely difficult to prevent the decrease of the groundwater level in the surrounding area. ”“ Chapter 4 Monitoring of water quality of groundwater, etc. 4-1 Monitoring of water quality of groundwater, etc. (1) The project entity is In order to prevent pollution of water quality such as groundwater and public water areas due to injection of chemicals, it is necessary to monitor the status of pollution of groundwater and public waters around the injection location of chemicals. " There is. The grout method by injecting a chemical solution is not intended to permanently solidify the soil or stop water, and it is necessary to give sufficient consideration to pollution.

(4) Double-pipe strainer double-phase type The double-pipe strainer double-phase type has a 2-shot type and a 1.5-shot type.
This is a ground injection method in which a shot method or a two-shot method and a one-shot method are alternately performed. A multiple pipe is used as an injection pipe rod, and a chemical solution is used for grout.

When cement grout and cement rapid hardening material are used as the primary injection material, or only cement grout is used as the secondary injection material, it is attempted to inject into the ground by the double pipe strainer multi-phase type (A) Multiple pipes are used The gelling time of the primary injection material at the time of doing is meaningless to use the multi-tube unless it is about 30 seconds or less, and since this multi-tube is used, it is inferior in economic efficiency to the single tube.

(B) Due to the double-pipe strainer multi-phase type, a special monitor equipped with a mixing device for two kinds of liquids, a check valve, etc. is required at the tip of the injection pipe rod, which is economical and construction Inferior in sex.

(C) When the gelling time when the cement grout and the cement quick-hardening material merge together is within 30 seconds, the construction can be performed for the purpose of filling voids or extremely coarse gaps,
The gelled hardened material has a very high strength, and in many grounds, it is often the case that the ground is opened or lifted up, and the surrounding structures may be adversely affected by displacement. Yes, and especially long-term injections should be avoided. Therefore, it is very difficult to use cement grout with such a short gelling time in a place where there are structures in the surrounding area such as an urban area with many underground buried objects and buildings or reinforcement of an existing coastal levee. It is a danger.

There are drawbacks such as Therefore, the grout used for the double pipe strainer multi-phase type is currently a chemical solution.

As described above, the technique using the injection pipe rod is divided into four types, that is, the one-shot system, the 1.5-shot system, the two-shot system (double-pipe strainer single-phase type), and the double-pipe strainer multi-phase type. And said. As the only example that does not belong to any of these four methods, the injection method is similar to the double tube strainer multi-phase type, the injection tube rod is a single tube rod, and it has been put to practical use under the name of multiple LW or mLW. There is a construction method.

(5) Multiple LW or mLW Construction Method In the claims of Japanese Patent Publication No. Sho 60-10066, which is the basis of this construction method, there is a description that "a solid chemical liquid is injected into a soft or leaking ground to form the ground. In the soil consolidation method that consolidates soil, (A) Suspension grout obtained by joining a suspension (liquid A) containing cement as an active ingredient and a water glass aqueous solution (solution B ') is injected into the soil. And (B) then, a solution obtained by adding the water-soluble reaction agent to the water glass aqueous solution (B 'solution) and stopping the merging of the suspension (A solution) containing cement as an active ingredient. Grout above
(A) consists of the step of injecting into the ground following the step,
As a result, (C) the composite grout method characterized by uniformly consolidating the coarse-grained soil layer and the fine-grained soil layer in the ground. It is described as ".

The grout of this method is a chemical solution, and is subject to the provisional guideline by the notification of the Ministry of Construction. Part of this provisional guideline is as described above, but according to the provisional guideline, “Chapter 2 Selection of chemical injection method” 2-3 Usable chemicals The chemical used for the chemical injection method is water glass for the time being. System chemicals (meaning chemicals whose main ingredient is sodium silicate; the same shall apply hereinafter) shall be limited to those that do not contain deleterious substances or fluorine compounds. " The gel reaction between water glass and cement is an electrical connection between (-) ions in water glass and (+) ions in cement, and is not directly related to the hydration hardening reaction of cement itself. Further, when the water in the ground is seawater, the water glass easily reacts with alkali ions such as sodium in the seawater when it comes into contact with the seawater to form an extremely soft gel. Further, not only does the sodium content in the water glass adversely affect the strength properties of the cement, but the sodium content in the water glass elutes into groundwater and the volume is significantly reduced. As a result, not only environmental pollution but also lack of strength and long-term reliability are the biggest drawbacks.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and was devised to solve the problems. The object is to use (A) a chemical solution. Pollution-free and permanent effect is achieved without using (B) multi-pipes, using single-pipe rods with excellent economy and workability as injection pipes, (C) surrounding ground and structures (D) It is to provide a ground pouring method using cement grout capable of uniformly consolidating or stopping the water without adversely affecting the soil.

[0020]

In order to achieve the above object, the present invention is directed to a plurality of grouts having different consolidating times while moving the injection tube inserted into the ground to change the injection stage. In the ground pouring method of pouring into the ground through the soil to consolidate or stop the water, (A) use a single pipe rod for the injection pipe inserted into the ground, and (B) as the primary pouring material for each stage. , Using a cement grout with a cement rapid hardening material gelation time of 30 seconds or more and within several minutes, (C) As a secondary injection material, the mixing of the cement rapid hardening material was stopped, and the gelling time Using a long cement grout, (D) Cement grout as the primary injection material and cement rapid hardening material are mixed in the injection tube of the single pipe rod and pressure-fed toward the tip, and the cement grout and cement are injected from the tip of the injection tube. Sudden Inject the mixed material of the material into the ground, fill the coarse gap by the consolidation of the mixed material to restrain the ground, and (E) Cement grout as the secondary injection material is injected through the injection pipe. It is constructed by the ground pouring method using cement grout, which is characterized by pouring into a small gap that is not filled in the filled area and uniformly consolidating or stopping the water.

In the present invention, the gelling time when the cement grout and the cement rapid hardening material merge is adjusted to within several minutes, and the primary injection material is first applied to the ground by the 1.5 shot method. It has been thought that cement particles do not enter unless there is at least several times the size of the soil particle gap by injecting it, filling the coarse gap in advance and restraining the ground. ,
Suspended particles of cement grout, which are then pumped as secondary injectant, actually enter even very small voids because the primary injectant fills the coarse voids.
At the same time, the cement grout that is pressure-fed as the secondary injection material is not filled with the primary injection material in advance because it is filled with rough gaps and weak portions, and therefore does not scatter away.

The grout used in the present invention is a cement, not a liquid chemical, and is highly safe against pollution and has a permanent effect. In addition, the gelling time when cement grout and cement rapid hardening material merge is within a few minutes, and the injection method is 1.5 shot method, so a single tube rod can be used. Extremely economical and easy to install.

[0023]

[Operation] When the target ground is composed of coarse soil, or when the groundwater flow is large, if the cement grout having a long gelation time is used for treatment, the injected grout is dispersed, diffused, or diluted. Further, even if the cement grout is allowed to penetrate into the soil particles only by such a one-shot method, in most cases, the cement grout easily flows out to the surface of the earth along the injection pipe rod instead of penetrating into the soil particles.

For this reason, in the present invention, cement grout and cement quick-hardening material are injected in advance by the 1.5-shot method to fill the coarse gaps in the ground and prevent the flow of groundwater to restrain the ground. Inject cement grout with long gelation time.

When the gelling time of the cement grout with the cement rapid hardening material is within 30 seconds, it is possible to carry out the construction for the purpose of filling voids or extremely coarse gaps,
Usually, in many grounds, the gelation time is extremely short and the gelled hardened material becomes too strong, so the ground is often opened or lifted up, and the surrounding structures are not displaced. The ground may not be effectively restrained because it may have adverse effects such as giving. Further, when the gelling time of cement grout with cement hardening material exceeds several minutes, conversely, this injection grout flows along the injection pipe rod or causes escape to a weak portion, so that each stage according to the present invention The effect of restraining the ground as the primary pouring material cannot be expected.

In the present invention, the gelling time of the cement grout with the cement quick-hardening material is 30 seconds or more, generally 1 minute or more and within a few minutes. In this case, the ground is pressed open unless a large amount of injection is continued more than necessary. Without doing or lifting
The ground can be restrained most effectively as the primary injection material. Therefore, the injection tube used in the present invention is a single tube rod.

In the present invention, since the grout used is cement and not a chemical solution, the injected grout is hardened by the hydration reaction or pozzolanic reaction of the cement itself. Furthermore, a cement rapid hardening material used for 1.5 shot injection is commercially available from Denka ES (trademark)
When DENKA ES hydrates with cement, calcium sulphoaluminate hydrate is formed, and the activity of tricalcium silicate and dicalcium silicate in the cement is significantly increased, and the hardening reaction proceeds with gelation. To do. This reaction is the hydration reaction of the cement itself, and Denka ES acts to accelerate the hydration reaction rate of the cement. Therefore, the cement and DENKA ES gelated product can maintain the permanent strength in terms of long-term properties like the cement, and the hydrate thereof is not eluted by groundwater or seawater. still,
The cement rapid hardening material used in the present invention is not limited to DENKA ES, and if it is a calcium aluminate type, it has the same effect as DENKA ES described above, and can be used.

[0028]

[Examples] In Minami-Matsuura District, Nagasaki Prefecture, a plurality of injections were carried out using cement grout and cement quick-hardening material having the following composition on the ground consisting of alternating layers of gravel layer, coarse sand layer and fine sand layer.

[0029] After drilling to a predetermined depth using the single tube rod 1, the single tube rod 1 is raised by 0.25 m to make this single tube rod 1 an injection tube.
The liquid is injected in equal amounts of 60 liters each by the 1.5-shot method to form the rough gap filling portion 2, and then the merging of the liquids B is stopped, and only the liquid A is injected by the one-shot method as the secondary injection.
0 liter was injected to form the small gap filling portion 3. And
This injection step was sequentially performed to a depth of 2 m to 1.5 m below the ground surface while pulling up the single pipe rod by 0.25 m. Also, at this time, A liquid and B by 1.5 shot injection
The gelation time of the liquid was 1 minute 30 seconds to 1 minute 40 seconds.

When the ground 5 was excavated and surveyed along the line of injection holes, solid bodies 4 were formed homogeneously regardless of whether it was a gravel, coarse sand, or fine sand layer and were continuous along the line of injection holes. It had been. Furthermore, although a maximum of 4.4 liters / min / m of water leakage had occurred in the site before the injection, it was possible to completely block water over the entire section of the injection hole row line after the injection.

[0031]

The single-tube rod 1 is inserted into the ground 5, and while moving the single-tube rod 1 to change the injection stage, cement grout is injected without using a chemical solution to consolidate or stop the ground. 1 of each stage in the watering method
Cement grout and cement quick-hardening material are pre-injected as the next injection material by the 1.5 shot method to fill the rough gap of the ground to form the rough gap filling part 2 and further prevent the flow of groundwater to prevent the ground. After restraining, the joining of the cement hardened material is stopped as a secondary injection material, and cement grout having a long gelation time is injected. Then, it has been considered that the cement particles do not enter unless there are at least several times or more gaps between the soil particles.
Since the coarse gap is filled with the primary injection material by the shot method, in actuality, a very small gap is entered to form the small gap filling portion 3. At the same time, the cement grout that is pumped as the secondary injecting material is preliminarily filled with the primary injecting material in the rough gap, the soft portion, or the highly permeable portion. There is nothing to do. Therefore, according to the present invention, the ground can be uniformly consolidated or stopped by using cement grout.

When the gelling time of cement grout with cement rapid hardening material is 30 seconds or more, generally 1 minute or more and within a few minutes, the ground is pressed open or lifted unless a large amount of injection is continued. Without this, the ground can be restrained most effectively as the primary injection material. Therefore, the gelling time of the cement grout with the cement rapid hardening material at the time of 1.5 shot injection used in the present invention is 30 seconds or more and within several minutes, and a single tube rod can be used as the injection tube.

Therefore, since it is not necessary to monitor the multiple pipes and the multiple pipe tips used in the two-shot system (double-pipe strainer single-phase type) and the double-pipe strainer multi-phase type, it is extremely economical and construction is possible. Is also easy.

In the present invention, since the grout to be used is a cement and not a chemical solution, it is excellent in terms of pollution prevention, and the injected grout is hardened by the hydration reaction or the pozzolanic reaction of the cement itself. A permanent effect is obtained. Further, the cement quick-hardening material used in the present invention is also non-polluting and permanent if commercially available electro-chemical industry Denka ES or other calcium aluminate system that works to accelerate the hydration reaction rate of cement grout is used. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a ground pouring method using the cement grout of the present invention. (A) The figure is a front view of the single tube rod. (B) is a front view of the state where the rough gap filling portion is formed. FIG. 7C is a front view of the state where the small gap filling portion is formed. (D) and (e) are front views of the injection method after the injection stage is moved.

[Explanation of symbols]

 1 Single tube rod 2 Coarse gap filling part 3 Small gap filling part

Claims (1)

[Claims] 1. A ground for consolidating or stopping the ground by pouring a plurality of grouts with different consolidation times into the ground through the injection pipe while moving the injection pipe inserted into the ground to change the injection stage. In the injection method, (A) a single pipe rod is used for the injection pipe inserted into the ground, and (B) as the primary injection material for each stage, the gelling time of cement grout with cement rapid hardening material is 30 seconds or more. (C) As a secondary injection material, use the cement grout with a long gel time to stop the mixing of the cement rapid hardening material, and use (D) the primary injection material. While mixing cement grout and cement quick-hardening material in the injection pipe of the single pipe rod, pressure is sent toward the tip, and the mixed material of cement grout and cement quick-hardening material is injected from the tip of the injection pipe into the ground to mix the material. Coarse due to consolidation The gap is filled to restrain the ground, and (E) the cement grout as the secondary injection material is injected through the injection pipe into the small gap that is not filled in the area where the mixed material is injected, and the ground is uniformly solidified. A ground pouring method using cement grout, which is characterized by binding or stopping water.