JPH06294118A - Stabilization of ground - Google Patents

Abstract

PURPOSE:To increase an effective utilization ratio of grout and stabilize ground, by adding an appropriate quantity of a material having a specified composition chosen out of a group comprising a fluidizing agent and a dispersant into a grout which is injected in the excavated ground. CONSTITUTION:When excavating water for soil and sand is injected in the ground to excavate the soil and sand and a grout is poured in the excavated area while discharging the excavated soil and sand as slurry up to the ground level, at least one kind of component chosen from bentonite, cellulose ether viscocity agent, Arabian rubber, as a dispersing agent in water is added in this grout at the ratio of 1-50kg per unit m<3> of grout. The grout is poured and charged in the excavated area of soil and sand from the grout inlet provided near the front at a farther position than a water-infection hole of a pouring pipe in order to form a solidified zone in the ground. In this way, poured grout is diluted by the agitation of the infected excavating water for soil and sand and prevented from discharging with the slurry And hence, the effective utilization ratio of grout is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sprays and injects water for earth and sand cutting into the ground to cut the earth and sand, and discharges the cut earth and sand to the surface of the earth as sludge drainage liquid, while injecting and filling grout into the cut area. The present invention relates to a method for stabilizing a ground by forming a hardened body by curing.

[0002]

2. Description of the Related Art For the purpose of improving soft ground, constructing underground structures, excavating ground, etc., to stop water against spring water, underground water, leaks, etc. in the ground, or to prevent the ground from collapsing. There is a high-pressure injection injection method as a ground stabilization method. As an example of this construction method, high-pressure water is injected and injected from the water injection hole of the injection pipe inserted and installed in the ground to cut the earth and sand in the required area, and the cut earth and sand is discharged to the surface as drainage mud liquid. On the other hand, there is a method of forming a hardened body by injecting and filling a curable material such as cement-based grout into the cutting region through a grout injection hole provided at a position closer to the tip than the water injection hole of the injection pipe. When the water for earth and sand cutting is injected and injected into the ground to cut the earth and sand and the grout is filled, generally, the injection pipe is injected and filled while rotating and retreating the injection pipe. A substantially columnar hardened body is formed on.

In this method, the state of dispersion of hydraulic cement particles is improved to improve the pumpability of the grout by a pump, the filling efficiency of the grout into the ground is enhanced, and the discharge of the cut soil to the above-ground portion is assisted. For that purpose, it is generally practiced to add an admixture for increasing the fluidity to the grout.

Examples of admixtures are alkali (earth) metal salts such as lignin sulfonic acid, naphthalene sulfonic acid, oxycarboxylic acid, polycarboxylic acid, alkylallyl sulfonic acid and melamine sulfonic acid, and their formalin condensates. Various derivatives have been used.

[0005]

In the conventional method,
To increase the diameter of the hardened body that is formed in the ground, increase the injection time of the earth and sand cutting water that is injected and injected into the ground to cut the earth and sand in the required area of the ground. Need to increase. However, if the amount of sediment cutting water injected is increased, the amount of sludge drainage increases, and the grout that has been injected and filled is diluted by the stirring action of the injected sand and sand cutting water, and the grout mixed in the sludge is As the amount increases, the amount of grout loss increases. For this reason, in order to obtain the design strength, it is necessary to increase the amount of grout to be injected and filled so as to compensate for the loss, which is a major problem in that the cost is increased, and improvement is strongly desired. It is rare.

An object of the present invention is to inject and inject water for earth and sand cutting into the ground through a water injection hole of an injection pipe inserted and installed in the ground to cut and cut earth and sand in a required area. While discharging earth and sand as mud liquid to the surface of the earth, a hardening material such as cement-based grout is injected and filled into the cutting area from a grout injection hole provided at a position closer to the tip than the water injection hole of the injection pipe to cure. As a method of improving the method of forming a hardened body in the ground, prevent the grout that has been injected and filled from being diluted under the influence of the stirring action of the water for cutting sand that is injected and injected and mixed into the sludge and discharged. Another object of the present invention is to provide a ground stabilization method capable of increasing the effective utilization rate of grout, reducing the amount of grout to be injected and filling, improving the construction efficiency, and reducing the amount of sludge drainage.

[0007]

Means for Solving the Problems As a result of research on a method for reducing the amount of grout to be injected and filled into the ground, the present inventors have found that the components specified in the present invention are added to the grout to be injected and filled. As a result, it was found that the amount of grout loss can be reduced and the above-mentioned problems in the conventional method can be solved, and the present invention was completed.

According to the present invention, "water for earth and sand cutting is injected and injected into the ground from a water injection hole of an injection pipe inserted and installed in the ground to cut the earth and sand in a required area, and the cut earth and sand. Is discharged as mud liquid to the surface of the ground, the grout injection hole provided at a position closer to the tip than the water injection hole of the injection pipe is used to inject and fill the cutting area with grout to form a hardened body in the ground. In the method, a ground stabilization method is characterized by adding an underwater dispersion inhibitor to the grout. "

In a preferred embodiment, the above-mentioned anti-dispersion agent in water comprises bentonite, cellulose ether thickener, acrylic thickener, polyvinyl alcohol, polyethylene oxide, sodium alginate, casein, guar gum and gum arabic. It is preferable that it is at least one component selected from the group. Moreover, it is preferable to add the above-mentioned dispersion inhibitor in water in an amount of 1 to 50 kg per 1 m ^{3 of} grout.

The details of the present invention will be described below. In the method of the present invention, as the water for cutting the sand, tap water, industrial water, river water, sea water, ground water, or supernatant water of the sludge discharged in the high-pressure injection method can be used. Further, in order to enhance cutting efficiency, it is preferable to entrain gas in the water for cutting sand and sand, and usually compressed air of 5 to 10 kg / cm ² can be used.

In the method of the present invention, at least one component selected from the group consisting of a fluidizing agent and a dispersant can be added to the earth and sand cutting water used.

As a fluidizing agent, lignin sulfonic acid,
Naphthalene sulfonic acid, oxycarboxylic acid, polycarboxylic acid, alkylallyl sulfonic acid, melamine sulfonic acid such as sodium or calcium alkali (earth)
Metal salts and at least one of these formalin condensates can be used.

As the dispersant, it is possible to use at least one of alkali metal salts of sodium silicic acid, metasilicic acid, phosphoric acid, polyphosphoric acid, and hexametaphosphoric acid, or sodium hydroxide. Examples of the alkali metal salts of silicic acids include sodium silicate, potassium silicate, lithium silicate, sodium metasilicate and the like. As the alkali metal salt of phosphoric acid, sodium phosphate,
Examples thereof include disodium phosphate, monosodium phosphate, sodium polyphosphate, sodium hexametaphosphate and the like.

[0014] The jet pressure of water for cutting sand is usually 30 to 1000
The range is kg / cm ² , preferably 100 to 600 kg / cm ² , and more preferably 150 to 500 kg / cm ² . Injection pressure is 30 kg
If it is less than / cm ^2, it will take a long time to cut the ground, and 1000 kg
Even if it exceeds / cm ² , the earth and sand cutting efficiency does not improve so much, and equipment such as pumps also requires large capacity and becomes large in size, which is not economical.

The amount of water for cutting sand is usually 10 to 10 minutes per minute.
It may be selected in the range of 200 liters, preferably 50-100 liters per minute.

In the method of the present invention, the hydraulic cement used as a grout to be injected and filled into the ground includes:
Various types of Portland cements such as normal Portland cement, early strength Portland cement, super early strength Portland cement, medium heat Portland cement, low heat Portland cement, sulfate Portland cement, high iron oxide Portland cement, white Portland cement; blast furnace cement, silica Cement, fly ash cement, masonry cement, expansive cement and other mixed cements; jet cement (ultra-fast cement)
Special cements such as alumina cement, colloidal cement, supertocolloidal cement and high sulfate slag cement; CaO ・ 2Al ₂ O ₃ , CaO ・ Al ₂ O ₃ , 3CaO ・
3Al ₂ O ₃ · CaSO ₄ , 11CaO · 7Al ₂ O ₃ · CaF ₂ ,
12CaO ・ 7Al ₂ O ₃ , 2CaO ・ Al ₂ O ₃ , 3CaO ・ Al
₂ O _3, may be mentioned crystalline calcium aluminates and amorphous calcium aluminate such as _{4CaO · Al 2 O 3 · Fe} 2 O 3. These hydraulic cements can be used alone or in combination of two or more. In addition,
It is also possible to replace a part of the hydraulic cement with fly ash, silica fume, granulated blast furnace slag, sewage sludge incineration residual ash, or the like.

In addition to the above, various types of gypsum such as type II anhydrous gypsum, gypsum dihydrate, α hemihydrate gypsum, β hemihydrate gypsum; various limes such as quicklime and slaked lime; kaolinite, montmorillonite Clay minerals such as (bentonite), halloysite, allophane; siliceous raw materials such as white carbon, colloidal silica, silica sol, silica fume; calcium carbonate, calcium carbonate / magnesium (dolomite), stone powder, diatomaceous earth or high pressure injection method The discharged sludge can be used together. Further, a curing accelerator or a curing retarder as a curing time adjusting agent may be used.

The amount of hydraulic cement used is 1 m ^{3 of} hardener.
It is appropriately selected within the range of 100 to 1500 kg.

In the present invention, as the water dispersion inhibitor added to the grout, a thickening agent for increasing the viscosity of the grout can be used. Bentonite, cellulose ether thickening agent, acrylic thickening agent, polyvinyl alcohol, polyethylene Oxide, sodium alginate, casein,
At least one component selected from the group consisting of guar gum and gum arabic is used.

Examples of the cellulose ether thickener include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl ethyl cellulose and carboxymethyl cellulose.

Examples of the acrylic thickening agent include polyacrylamide, sodium polyacrylate, a copolymer of acrylamide and sodium acrylate, and a partially hydrolyzed polyacrylamide.

In the method of the present invention, the amount of the dispersion inhibitor in water used is in the range of 1 to 50 kg, preferably 5 to 30 kg, and more preferably 10 to 1 m ^{3 of} grout.
It is preferable to add it in the range of 25 kg.

If the amount of the dispersion inhibitor in water is less than 1 kg, the effect of preventing grout from mixing in the sludge is small and the amount of grout loss is large, so that the amount of grout to be injected and filled cannot be reduced. On the other hand, if the amount exceeds 50 Kg, the viscosity of the grout becomes too large and the handling becomes difficult.

The grout has, as an admixture, ligninsulfonic acid, naphthalenesulfonic acid, oxycarboxylic acid,
Various salts such as polycarboxylic acid, alkylallyl sulfonic acid, melamine sulfonic acid, and their formalin condensates can also be used. Examples of the salt include alkali (earth) metal salts such as sodium salt and calcium salt, and examples of the derivative include a formalin condensate, a polyol complex, and a rhodane compound. The admixture is usually added in an amount of 0.01 to 3 parts by weight as an effective component per 100 parts by weight of hydraulic cement.

Further, in addition to the admixture, the grout contains, as an additional component, at least one kind of various active agents selected from the group consisting of lower alcohols, organic polar compounds, mineral oils and silicone resins. It can also be added.

The filling pressure of grout is usually 5 to 30 kg.
/ Cm ² range is good, filling speed is usually 50-300 per minute
It may be selected in the range of liter.

[0027]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. Examples and comparative examples. As water for cutting earth and sand, tap water and various kinds of water prepared by adding 5% of the fluidizing agent or dispersant shown in Table 1 to tap water were prepared. As the grout, a cement-based grout obtained by blending ordinary Portland cement and water in a weight ratio of 1: 1 is used as a basic material, and various water dispersion inhibitors are added thereto in the amount ratio shown in Table 1. Various prepared grouts were prepared. Insert and install the injection pipe in the construction ground where the soil is cohesive soil,
A position closer to the tip than the water injection hole of the injection pipe while discharging the prepared earth and sand cutting water from the water injection hole of the injection pipe to cut the earth and sand and discharging the cut earth and sand as muddy liquid to the surface From the grout injection hole provided in, the grout was injected and filled into the region where the earth and sand were cut to form a hardened body in the ground. The earth and sand cutting area is 3 to 5 m deep from the ground surface.
The section was m.・ Specifications of injection pipe used: Triple pipe with a pipe diameter of 90 mm, injection nozzle hole diameter 2.4 mm, and injection injection conditions were set as follows.・ Water injection pressure for earth and sand cutting: 400 kg / cm ² , ・ Discharge rate: 70 liters per minute, ・ Introduced compressed air pressure: 7 kg / cm ² ,
・ Introduced air volume: 2 m ³ / min ・ ・ Grout injection filling pressure: 15 kg / cm ²・ ・ Discharge rate: 180 liters / min ・ ・ Injection tube rotation speed: 5 rpm. Existence,
Table 1 shows the amount of grout injected, the volume of the formed hardened body (solidified soil), and the compressive strength value (after 28 days).

[0026]

[Table 1]

As shown in the comparative example in Table 1, 1 m of grout
^{When the} amount of the water dispersion inhibitor per ³ is less than 1 kg, the grouting breathing rate is 5 to 10%,
To form a cured product with a volume of 3.0-3.1 m ³ ,
The grout injection amount was required to be 3.0 to 3.6 m ³ .
A fragile portion was formed on the upper portion of the formed cured body.

On the other hand, in each of the examples satisfying the requirements of the present invention, no breathing phenomenon of grout was observed in any of the examples, and the amount of grout injection required to form a cured body having a similar volume was 2.5. It was ~2.6 m ^3. The reduction rate of the grout injection amount was 17 to 28% with respect to the required amount of grout when the water dispersion inhibitor was not used.
(Example A group; Experiment number: 3 to 5,). No brittle portion was formed in the formed cured body.

[0029]

According to the method of the present invention, water for earth and sand cutting is injected and injected into the ground to cut the earth and sand, and the cut earth and sand is discharged to the surface of the earth as drain mud liquid, and the cut area is injected and filled with grout. In the method of forming a hardened body to stabilize the ground, it is prevented that the filled grout is affected by the stirring action of the water for sand and sand injection and is diluted and mixed into the sludge and discharged. The effective utilization rate of the grout can be increased to reduce the amount of grout to be injected and filled, the construction efficiency can be improved, and the amount of sludge liquid can be reduced. In addition, the grout that satisfies the requirements of the present invention is
No breathing phenomenon is observed and no brittle portion is formed on the upper part of the formed cured body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Kobayashi 10-1 Daikokucho, Tsurumi-ku, Yokohama-shi, Kanagawa Nitto Chemical Industry Co., Ltd. Central Research Laboratory

Claims (3)

[Claims] 1. A water injection hole of an injection pipe inserted and installed in the ground to inject water for earth and sand cutting into the ground to cut the earth and sand in a required area and to drain the cut earth and sand. While discharging to the ground surface as a liquid, from a grout injection hole provided at a position closer to the tip than the water injection hole of the injection pipe, in a method of injecting and filling grout into the cutting region to form a hardened body in the ground, A method for stabilizing the ground, comprising adding an underwater dispersion inhibitor to the grout. 2. The water dispersion inhibitor is at least one selected from the group consisting of bentonite, cellulose ether thickeners, acrylic thickeners, polyvinyl alcohol, polyethylene oxide, sodium alginate, casein, guar gum and gum arabic. The method for stabilizing the ground according to claim 1, wherein 3. The ground stabilization method according to claim 1, wherein the water dispersion inhibitor is added in an amount of 1 to 50 kg per 1 m ^{3 of} grout.