JPH0680965A - Method for stabilizing ground - Google Patents

Abstract

(57) [Summary] [Structure] The weight ratio of the lignin sulfonic acid type admixture and the naphthalene sulfonic acid type admixture is 1: 9 to 9:
In the range of 1 to 100 parts by weight of hydraulic cement as the total amount of each of the above-mentioned active ingredients, the hydraulic cement milk added in the range of 0.1 to 3 parts by weight is injected into the ground to form a solid-sand solid body. Stabilize. [Effect] The amount of hydraulic cement milk injected per unit time can be increased, the ratio of the amount of solidified sand to the amount of grout injected is increased, and the compression strength value is high. Let it form. It is possible to greatly improve the construction efficiency for forming a solidified sediment body having a target diameter and reduce the amount of sludge discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stabilizing the ground by injecting hydraulic cement milk into the ground and hardening it to form a solidified sediment body, thereby stabilizing the ground.

[0002]

2. Description of the Related Art In the improvement of soft ground, foundation work of underground structure, excavation work of ground, etc., for the purpose of stopping water against spring water, underground water, leakage etc. in the ground, or preventing the ground from collapsing, The hydraulic cement milk is poured into the ground, and the hydraulic cement and earth and sand are stirred and mixed to cure. When injecting hydraulic cement milk into the ground,
Generally, by rotating and raising a hydraulic cement milk injection rod that has been inserted and installed in the ground, the hydraulic cement milk is injected and hardened to form a substantially solidified solid sediment in the ground. Is being formed.

At this time, the dispersion state of the cement particles in the hydraulic cement milk is improved to improve the pumpability by the pump, the pressure loss at the time of high-pressure injection is reduced, the injection distance of the cement milk is increased, and It is common practice to add an admixture to hydraulic cement milk for the purpose of improving mixing efficiency and helping discharge the sludge generated when soil in the ground is replaced by cement milk to the above-ground portion. ing.

As the admixture, various salts such as lignin sulfonic acid, naphthalene sulfonic acid, oxycarboxylic acid, polycarboxylic acid, alkylallyl sulfonic acid, melamine sulfonic acid and their formalin condensates are used. ing.

[0005]

Among the above-mentioned admixtures conventionally used, the ligninsulfonic acid-based admixture is
Since the effect of reducing the viscosity of hydraulic cement milk is small, it is not possible to improve the pumpability of hydraulic cement milk with a pump, and since it does not reduce the pressure loss during high-pressure injection of hydraulic cement milk, it does not increase the injection distance. However, there is a problem that the durability of the nozzle tip is also affected.

On the other hand, the naphthalene sulfonic acid-based admixture has a great effect of reducing the viscosity of hydraulic cement milk, improves the pumpability of hydraulic cement milk by a pump, and high-pressure injection of hydraulic cement milk. The pressure loss at the time is reduced, the injection distance is increased, and the service life of the nozzle tip is lengthened. However, when the hydraulic cement milk containing naphthalene sulfonic acid-based admixture is injected into the ground and mixed with the earth and sand, it does not mix well with the earth and sand, and the formed sediment solid is uneven. In addition, there is a problem that the amount of solidified sand per amount of the injected liquid is small and the injection and solidification efficiency is not good.

An object of the present invention is to reduce the viscosity of hydraulic cement milk when pumping hydraulic cement milk containing an admixture into the ground to harden it to form a solidified soil-sand mixture, and to improve the pumpability by a pump. Improved, the pressure loss during high-pressure injection is reduced to increase the injection distance, the nozzle tip life is extended, and the mixing property of hydraulic cement milk injected into the ground is improved by mixing it with soil. Can form a solid sediment solid, the amount of solid sediment per injection liquid amount is large, it is possible to shorten the injection time of hydraulic cement milk to create a sediment solid of the target diameter,
An object of the present invention is to provide a ground stabilization method capable of improving the construction efficiency and reducing the amount of sludge discharged.

[0008]

[Means for Solving the Problems] The present inventors have found that a ligninsulfonic acid-based admixture and a naphthalenesulfonic acid-based admixture are added to a hydraulic cement milk used in a ground stabilization method, particularly a high-pressure injection injection method. Surprisingly, the disadvantage that the miscibility of hydraulic cement milk with earth and sand when using a naphthalene sulfonic acid-based admixture is improved is improved by adding them in a specific amount ratio. The present invention has been completed, knowing that the above can be solved.

According to the present invention, a "lignin sulfonic acid-based admixture is used as the admixture when the hydraulic cement milk to which the admixture is added is injected into the ground and hardened to form a solidified soil-sand consolidate to stabilize the ground. And naphthalene sulfonic acid-based admixture in a weight ratio of each active ingredient in the range of 1: 9 to 9: 1, and 0.1 to 3 parts by weight per 100 parts by weight of hydraulic cement as the total amount of each active ingredient. The method of ground stabilization is characterized by injecting hydraulic cement milk added in the range of ".

In the method of the present invention, as the hydraulic cement used for the hydraulic cement milk, there are ordinary Portland cement, early strength Portland cement, super early strength Portland cement, moderate heat Portland cement, low heat Portland cement and sulfate Portland cement.・ Various Portland cements such as high iron oxide type Portland cement and white Portland cement, mixed cements such as blast furnace cement, silica cement, fly ash cement, masonry cement, expansive cement, jet cement (super rapid hardening cement), alumina cement・ Special cements such as colloidal cement, supertocolloidal cement, high sulfate slag cement, C
aO ・ 2Al ₂ O ₃ , CaO ・ Al ₂ O ₃ , 3 CaO ・ 3Al ₂ O ₃
・ CaSO ₄ , 11 CaO ・ 7Al ₂ O ₃・ CaF ₂ , 12 CaO ・
7Al ₂ O ₃ , 2 CaO ・ Al ₂ O ₃ , 3CaO ・ Al ₂ O ₃ , 4
Examples thereof include crystalline calcium aluminates such as CaO · Al ₂ O ₃ · Fe ₂ O ₃ and amorphous calcium aluminates. These hydraulic cements can be used alone or in combination of two or more. Incidentally, a part of the hydraulic cement described above is fly ash, silica fume,
It can be replaced with granulated blast furnace slag, gypsum, sewage sludge incineration residual ash, etc.

The amount of hydraulic cement used is appropriately selected within the range of 100 to 1500 Kg per 1 m ^{3 of} hydraulic cement milk.

The ligninsulfonic acid-based admixture used in the method of the present invention contains at least one component selected from the group consisting of various salts or derivatives of ligninsulfonic acid. As the salt of lignin sulfonic acid,
Alkali (earth) metal salts such as sodium salt and calcium salt, and examples of ligninsulfonic acid derivatives include ligninsulfonic acid polyol complex,
Examples thereof include lignin sulfonic acid rhodan compound, lignin sulfonate cellulose ether, and lignin sulfonic acid formalin condensate.

The naphthalenesulfonic acid-based admixture used in the method of the present invention contains at least one component selected from the group consisting of various salts or derivatives of naphthalenesulfonic acid. Examples of the naphthalene sulfonic acid salt include alkali (earth) metal salts such as sodium salt and calcium salt, and examples of the naphthalene sulfonic acid derivative include naphthalene sulfonic acid polyol complex, naphthalene sulfonic acid rhodan compound,
Examples thereof include naphthalene sulfonate cellulose ether and naphthalene sulfonic acid formalin condensate.

In the method of the present invention, the weight ratio of each active ingredient of the lignin sulfonic acid type admixture and the naphthalene sulfonic acid type admixture is 1: 9 to 9: 1, preferably 3: 7 to.
It is preferable that the range is 7: 3. When the ratio of the amount of each active ingredient of the lignin sulfonic acid type admixture or the naphthalene sulfonic acid type admixture in the total amount of each active ingredient of the admixture is less than 10%, the combined effect cannot be expected and the hydraulic property The behavior of cement milk is as described above.
The same as when using the naphthalene sulfonic acid type admixture or the lignin sulfonic acid type admixture, respectively,
Not suitable for the purpose of the invention.

In the method of the present invention, the lignin sulfonic acid type admixture and the naphthalene sulfonic acid type admixture are in the range of 0.1 to 3 parts by weight per 100 parts by weight of hydraulic cement as the total amount of each active ingredient. Is added. If the amount is less than 0.1 parts by weight, the effect of adding an admixture cannot be expected, the mixing property of hydraulic cement milk with soil is not improved, and hydraulic cement milk is used to form a solid-sand consolidate having a target diameter. It is necessary to prolong the injection time, the amount of sludge increases and the construction efficiency decreases. On the other hand, when it is used in an amount of more than 3 parts by weight, when the hydraulic cement milk injected into the ground is mixed with earth and sand, the viscosity is rather increased and the miscibility with earth and sand is decreased, and the formed solid-sand solid body is formed. May be non-uniform, and hardening may be delayed or the solidified state may be uneven, resulting in a large variation in the strength of the solidified sediment body.

In addition to the hydraulic cement milk containing the above admixture, various types of gypsum such as type II anhydrous gypsum, gypsum dihydrate, α hemihydrate gypsum, β hemihydrate gypsum; various limes such as quick lime and slaked lime; Kaolinite, Montmorillonite, Halloysite,
Clay minerals such as allophane; siliceous raw materials such as white carbon, colloidal silica, silica fume; calcium carbonate, stone powder, diatomaceous earth, or sludge discharged in the high-pressure injection method can be used together. Furthermore,
It is also possible to use a curing accelerator or a curing retarder as a curing time regulator.

The method of the present invention can be applied to a method in which hydraulic cement milk and earth and sand are stirred and mixed in the ground to be hardened to form an earth and sand solid body. The high-pressure injection injection method in the ground stabilization method includes a method of injecting hydraulic cement milk as grout into the ground at high pressure to directly cut the earth and sand, and agitating and mixing the hydraulic cement and earth and sand to harden it. , There is a method of injecting high-pressure sand and sand cutting water into the ground to cut the earth and sand while injecting hydraulic cement milk as grout into the ground and stirring and mixing the hydraulic cement and earth and sand to harden it. . In each of these construction methods, the hydraulic cement milk and the earth and sand are stirred and mixed in the ground, so that the method of the present invention can be applied.

In the method of directly injecting hydraulic cement milk into the ground at a high pressure to directly cut the earth and sand, the injection pressure of the hydraulic cement milk is usually 30 to 1000 kg / cm ² , preferably 100 to 600 kg / cm 2. ² , more preferably 150-500 kg
The range of / cm ² is good. If the injection pressure is less than 30 kg / cm ^2, it will take a long time to cut the ground, and if it exceeds 1000 kg / cm ² , the loss of hydraulic cement milk will increase, and equipment such as pumps will also require large capacity and will be large. It is not economical.

[0019]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. Examples and comparative examples. Ordinary Portland cement and water were mixed at a weight ratio of 1: 1 and lignin sulfonic acid-based admixture and naphthalene sulfonic acid-based admixture were added and kneaded at a ratio shown in Table 1 as a grout to obtain a grout. A hydraulic cement milk was prepared. The obtained hydraulic cement milk was poured into a section of 3 m of 5 to 8 m from the ground surface in the ground. The soil quality of the improved section was cohesive soil. The injection construction conditions were set as follows. Injection pressure: 200 kg / cm ² , introduced compressed air pressure: 7 kg / cm
² , injection nozzle diameter: 2.8 mm, grout discharge: 70 liters per minute of water, injection rod speed: 8 rpm., Injection rod lifting time per injection step 1 m: 20 minutes, lignin sulfone under each condition The weight ratio of each active ingredient of the acid-based admixture and the naphthalene sulfonic acid-based admixture, the volume ratio of the total amount of each active ingredient of the admixture to the hydraulic cement, the amount of grout injected, and the solidification of the formed sediment solid Amount of solidifying sand and compressive strength value (28-day strength) and effective solidification efficiency-ratio of solidifying sand amount to grout injection amount (volume ratio)
Is shown in Table 1.

[0020]

[Table 1]

Under the above-mentioned injection conditions, in the comparative example which did not satisfy the requirements of the present invention, the grout injection amount of 60 liters per minute could not be secured. (Experimental number: 1,2,4,5). In addition, as shown in Table 1, in each comparative example, the amount of solidified sand of the formed solidified sand was less than 5 m ³ , and the compressive strength value was The variation of (28-day strength) was large. (Experiment number:
1-7).

On the other hand, in each of the examples satisfying the requirements of the present invention, the grout injection amount of 60 liters per minute or more could be secured. Then, the effective solidification efficiency, which is shown by the ratio (volume ratio) of the amount of solidified sand to the amount of grout injected, is improved, the amount of solidified sand exceeds 5 m ³ , and the compressive strength value (28-day strength) is high, Moreover, it was possible to obtain a stable solidified sediment body. (Experiment number: 11-19).

[0023]

[Effects of the Invention] In a ground stabilization method in which a hydraulic cement milk containing an admixture is injected into the ground and hardened to form a solidified sediment body, a ligninsulfonic acid-based admixture and a naphthalenesulfonic acid-based admixture are prepared. In combination with, by adding to the hydraulic cement milk within the range of a specific amount ratio specified in the present invention, while reducing the viscosity of the hydraulic cement milk, the hydraulic cement milk injected into the ground is soil When mixed with, it improves the mixing property with earth and sand without increasing the viscosity, has a large amount of solidified sand, and has a high compressive strength value (28-day strength) and stable solidification of earth and sand. The body can be formed. By the method of the present invention, it is possible to reduce the viscosity of hydraulic cement milk and increase the injection amount of hydraulic cement milk per unit time, and increase the ratio of the amount of solidified sand to the amount of grout to increase the effective solidification. The binding efficiency is improved. These two effects frighten, and because the injection time of hydraulic cement milk to create a solidified sand / sand consolidate of the desired diameter can be shortened, the construction efficiency can be greatly improved and the amount of sludge discharged can be greatly improved. It can be reduced.

 ─────────────────────────────────────────────────── ─── 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 (5)

[Claims] 1. A lignin sulfonic acid-based admixture and naphthalene are used as the admixtures when a hydraulic cement milk containing an admixture is injected into the ground and hardened to form a solidified soil-sand solid to stabilize the ground. A sulfonic acid-based admixture in a weight ratio of each active ingredient in the range of 1: 9 to 9: 1, and
A method for ground stabilization, comprising injecting hydraulic cement milk added in a range of 0.1 to 3 parts by weight per 100 parts by weight of hydraulic cement as a total amount of each of the active ingredients. 2. A ligninsulfonic acid-based admixture is an alkali metal salt of ligninsulfonic acid, an alkaline earth metal salt, a polyol complex, a rhodane compound, a cellulose ether,
The ground stabilization method according to claim 1, which comprises at least one component selected from the group consisting of formalin condensates. 3. The naphthalene sulfonic acid-based admixture is at least one selected from the group consisting of an alkali metal salt of naphthalene sulfonic acid, an alkaline earth metal salt, a polyol complex, a rhodan compound, a cellulose ether and a formalin condensate. The ground stabilization method according to claim 1, wherein the ground stabilization method comprises a component. 4. The weight ratio of each active ingredient of the lignin sulfonic acid type admixture and the naphthalene sulfonic acid type admixture is 3: 7 to.
The ground stabilization method according to claim 1, wherein the method is 7: 3. 5. A hydraulic cement milk containing 30 to 1000 kg / cm ²
The method for stabilizing the ground according to claim 1, wherein the pressure is applied to inject into the ground.