JP3278196B2 - Soft ground reinforcement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for strengthening soft ground. More specifically, by solidifying in the ground a hardened injectable slurry composed of cement, water and a dispersant, and a soil dispersed slurry obtained by mixing the soil in the soft ground, the hardened ground is formed in the soft ground. The present invention relates to a method for strengthening soft ground using an improved curable filler slurry.

[0002]

2. Description of the Related Art In a method of improving a soft ground, a soil in the ground is cut off while supplying a high-pressure hardening material slurry and high-pressure air, and a soil dispersion slurry comprising the hardening material slurry and the shaved soil. There is known a method of strengthening the soft ground by filling the solidified space with the ground and solidifying it.

[0003] Japanese Patent Publication No. 55-35531 discloses that
A method is disclosed in which a triple pipe is inserted into a soft ground, and while rotating the triple pipe, the ground in the radial direction is crushed by high-speed jet water and an air jet, and cement slurry is injected.

[0004]

In the conventional soft ground improvement method, the soil in the ground is cut off while supplying high-pressure hardening material slurry and high-pressure air, and the hardening material slurry and the shaved soil are removed. Soil dispersion slurry consisting of
In the method of reinforcing soft ground by filling and solidifying the shaved space, a hardenable injection slurry made of cement, water and a dispersant is used. The soil dispersion slurry composed of the hardenable injection material slurry and the cut soil is liable to decrease in fluidity, cutting is not efficiently performed in the ground, and the hardenable injection material slurry is not ground. The range of the ground cannot be extended over a wide area, and the ground cannot be extended. In addition, the decrease in the fluidity of the soil dispersion slurry impedes the discharge of excess soil dispersion slurry generated by feeding high-pressure hardening material slurry and high-pressure air to the ground. In some cases, the hole may be closed or the ground may be raised or deformed, resulting in interruption of the construction. In recent years, from the viewpoint of effective use of land, it is necessary to strengthen recent construction methods deeper than conventional construction methods. It is necessary to maintain the fluidity of the soil dispersion slurry in order to discharge the soil dispersion slurry to the ground more smoothly as the improvement portion is deeper.

Further, according to the method disclosed in Japanese Patent Publication No. 55-35531, although the fluidity of the soil dispersion slurry is relatively small, a large amount of water is jetted by the high-speed jet water to scrape off the target ground. A large amount of cutting slime including waste soil and cement slurry is discharged to the ground. This cutting slime is treated as waste, but in recent years the disposal of construction waste has become a major social issue. Disposal of these large amounts of cutting slime not only creates new problems but also hinders the construction itself. May come.

The present invention overcomes these disadvantages and provides an improved curable injectable slurry to improve the fluidity retention of the curable injectable slurry and the ground dispersal slurry with the cut soil. It is something to offer. It is another object of the present invention to provide an improved method of strengthening the ground using an improved curable injectable slurry.

[0007]

Means for Solving the Problems The soft ground strengthening method of the present invention is characterized in that a pressure-resistant multi-tube having a liquid ejection port and an air ejection port on a tip side surface is inserted into an existing hole of the soft ground , While rotating the multi-tube around the axis, a high-pressure curable injecting slurry is fed inside the multi-tube and high-pressure air is fed outside the multi-tube.
By shaving the soil in the ground and gradually raising the multi-pipe, the space around the multi-pipe extending from the tip of the multi-pipe that was initially inserted to the desired lifting height is shaved with the hardenable injection material slurry. Filled with the soil dispersion slurry made of soil, and the volume of the soil dispersion slurry and air exceeding the volume of the shaved soil is discharged to the ground along the outer wall of the multi-pipe, and the soil filled in the ground. In a method for strengthening soft ground, comprising solidifying a dispersion slurry, as a curable injecting material slurry, cement, water, a dispersant, and a dispersant of 0.02 to 0.2 wt.
It is characterized by using a curable injectable slurry containing 2.00 times the gluconate as a setting retarder .

[0008] The soft ground has a ground compression strength of 1K.
The material having a gf / cm ² or less is usually referred to, but in some cases, a ground having a strength higher than that may be used. The method of the present invention can be operated conventionally. The multi-tube has a fluid ejection hole and an air ejection hole at the tip, and the diameter is 5 to 5.
It can be used in various ways depending on the ground to be improved at about 30 cm. These multiple pipes can be inserted from guide holes pre-drilled from the ground surface into the ground. By sending high-pressure hardening material slurry and high-pressure air together into these multiple pipes and rotating them, the soil in the ground can be scraped off by the squirting hardening material slurry and air. The pressure of the curable injection material slurry sent into the multi-tube is several tens to several hundreds kg / cm ² . The air pressure at that time is at most 10 kg / cm ² and usually 7 kg.
/ Cm ² .

[0009] The rotation and lifting of the multiple pipes cut the soil into a columnar shape, and a soil dispersion slurry was formed in the ground by mixing the shaved soil with the hardening material slurry.
The volume ratio of the soil in the ground and the hardenable injection material slurry contained in the soil dispersion slurry is 1.0 in the soil in the ground and 0.2 in the hardenable injection material slurry. 1.0
The degree is preferred. The rotation speed of the shaft of the multi-tube is 1 to 20 r.p.
m, the lifting speed is controlled at 1 to 5 m / h, and the lifting height can be raised to a level that leaves about 1 m underground. An amount of the soil dispersion slurry that fills the space of the shaved soil remains in the ground, but the amount of the soil dispersion slurry exceeding the volume of the shaved soil is discharged to the ground. This exhaust is discharged together with the air sent along the outer wall of the multi-tube. Soil dispersion slurry remaining in the ground
Solidifies in several hours to one day, and a solid ground is formed in the ground. In this way, a columnar improved ground having a depth of about 1 to several tens of meters and a diameter of about 1 to 10 m can be constructed in the ground. The composition of the cement, water, and dispersant of the curable injectable slurry used in these compositions is, as a typical standard formula, 750 kg of water, 1 kg of water and 1 dispersant for 760 kg of cement.
A composition consisting of 2 kg is generally used. The curable injectable slurry used in the present invention has a weight ratio of 0.02 to 2.00 times the solid content of the dispersant in the slurry comprising cement, water and the dispersant, and is preferably 0 to 2.0. .10
Contains 1.50 times oxycarboxylic acid or its water-soluble salt.

As the cement used in the present invention, ordinary portland cement, early-strength portland cement,
Various portland cements such as moderate heat Portland cement, mixed cements such as blast furnace cement, silica cement and fly ash cement, special cements such as alumina cement, oil well cement, cement for grout, sludge solidifying material, cement for solidifying harmful substances And the like. One or more of these cements can be used.

The dispersing agents used in the present invention are those usually used as admixtures for cement, for example, water-soluble salts of naphthalenesulfonic acid formalin condensate and water-soluble salts of polyalkylallylsulfonic acid formalin condensate. , A water-soluble salt of melamine sulfonic acid formalin condensate,
A water-soluble salt of a ligninsulfonic acid formalin condensate, such as a sodium salt and a calcium salt. Furthermore, a polyol complex is mentioned. These dispersants can be used in the form of a solid or an aqueous solution.
Further, one kind or a mixture of two or more kinds may be used.

The oxycarboxylic acid or its water-soluble salt used in the present invention includes gluconic acid, glycolic acid,
α-oxybutyric acid, citric acid, tartaric acid, malic acid, lactic acid,
Salicylic acid, p-oxybenzoic acid, gallic acid and the like, and the water-soluble salts thereof include sodium, potassium,
Alkali metal salts such as lithium or calcium,
It is an alkaline earth metal salt such as magnesium, and preferably a gluconate such as sodium gluconate. These oxycarboxylic acids or water-soluble salts thereof may be added as such or as an aqueous solution. Further, one kind or two or more kinds may be mixed.

Slurry comprising cement, water and dispersant
The order of addition of the oxycarboxylic acid or its water-soluble salt to the compound is not particularly required, and may be in any order. The mixing method is 0 to 60 using an ordinary mixer or the like.
It can be carried out at a temperature of ° C within 30 minutes and usually within several minutes.

[0014]

In the method for strengthening soft ground according to the present invention, the air is blown together with the hardening material slurry to increase the distance of shaving the soil in the vertical direction from the axis of the multi-pipe. The soil can be efficiently removed. Further, the curable injection material slurry sent from the multiple pipes is immediately discharged into the ground and its pressure is reduced, so that it does not flow backward from the air ejection holes. In the soil dispersion slurry composed of the cement slurry and the soil, the formation of the initial hydrated gel of the cement causes the gel to cover the soil particles, so that the fluidity of the slurry decreases over time. The dispersing agent in the hardening injecting material slurry acts to enhance the dispersibility of the soil particles and the cement particles in the soil dispersion slurry, but a decrease in fluidity due to the formation of the initial hydrated gel of the cement is inevitable. The oxycarboxylic acid or its water-soluble salt added to the hardenable injection material slurry delays the formation of the initial hydration gel of the cement in the soil dispersion slurry and maintains the fluidity of the soil dispersion slurry for a long time. Conceivable.

When the amount of the oxycarboxylic acid or the water-soluble salt thereof is less than 0.02 times by weight based on the solid content of the dispersant of the curable injectable slurry composed of cement, water and the dispersant, Unable to achieve the fluidity retaining effect of the soil dispersion slurry consisting of the hardenable injection material slurry and the cut soil,
On the other hand, when the amount of oxycarboxylic acid or its water-soluble salt exceeds 2.00 times by weight, the hydration reaction of cement is conspicuously delayed, resulting in poor curing.

[0016]

EXAMPLES The sample soil used was a commercially available Kibushi clay adjusted to a water content of 80%. As the cement, ordinary Portland cement was used. As a dispersant, a sodium salt of a melaminesulfonic acid formalin condensate was used in a 35% by weight aqueous solution. Sodium gluconate was used as the water-soluble salt of oxycarboxylic acid.

The soil dispersion slurries of Examples 1 to 4 shown in Table 1 were obtained by adjusting and mixing the sample soil, cement, water, dispersant and oxycarboxylate. As a comparative example, a soil dispersion slurry of Comparative Examples 1 to 3 shown in Table 1 was obtained by adjusting and mixing a sample soil, cement, water and a dispersant. Using Examples 1 to 4 and Comparative Examples 1 to 3, the measurement of the fluidity retention time and the measurement of the compressive strength of the hardened material of the soil dispersion slurry were performed.

The fluidity retention time was measured by setting the fluidity immediately after mixing of the soil dispersion slurry to a P-roof flow value of 9 to 12 seconds, and thereafter measuring the P-roof flow value every 5 minutes. The time until the value exceeded 16 seconds was taken as the fluidity retention time. The compressive strength was measured by using a soil-dispersed slurry as a compact and curing it for 7 days under moist air, and then measuring the uniaxial compressive strength with a universal strength measuring device.

Table 1 Example and No. Soil dispersion slurry-mixing ratio (parts by weight) Sample soil Cement Water Dispersant Sodium gluconate Example 1 100 40 40 0.5 0.02 Example 2 100 40 40 0.5 0.1 Example 3 100 40 40 0.5 0.25 Example 4 100 40 40 1.0 0.1 Comparative Example 1 100 40 40 0.5 ─ Comparative Example 2 100 40 40 ─ 0.1 Comparative Example 3 100 40 40 0.5 0.5 Table 2 Example and No Fluidity retention time Uniaxial compressive strength (Kgf / cm ² ) Example 1 1 hour 15.2 Example 2 2 hours 30 minutes 15.5 Example 3 6 hours 15.0 Example 4 2 hours 40 minutes 16 3.3 Comparative Example 1 10 minutes 15.0 Comparative Example 2 5 minutes 15.8 Comparative Example 3 12 hours 3.5 From Table 2, as shown in Examples 1-4, a slurry comprising cement, water and a dispersant. When sodium gluconate is added in a weight ratio of 0.11 to 1.43 times the solid content of the dispersant and mixed with the sample soil, the desired fluidity of 1 to 6 hours is obtained. Is maintained, and the compressive strength is 15 to
It is as high as 16.3 kgf / cm ² .

In Comparative Example 1, since sodium gluconate was not added to the slurry, the compressive strength was high, but the retention time of fluidity was short. In Comparative Example 2, since no dispersant was used, the dispersibility of the soil particles and cement particles in the aqueous dispersion medium in the soil dispersion slurry could not be increased,
Addition of sodium gluconate failed to extend the fluid retention time.

In Comparative Example 3, since the addition ratio of sodium gluconate to the solid content of the dispersant in the soil dispersion slurry was too large, the solidification of the slurry was delayed, and the wet dispersion was cured for 7 days. After measuring the compressive strength, it was 3.5 kgf.
/ Cm ² .

[0022]

According to the present invention, as shown in the embodiment, by using a curable injection material slurry composed of cement, water, a dispersant, and oxycarboxylic acid or a water-soluble salt thereof, the injection material slurry can be used. -And the fluidity of the soil dispersion slurry consisting of the shaved soil is maintained. As a result, the ground can be efficiently cut, the ground can be improved in a wide range as needed, and the soil dispersion slurry can be smoothly discharged to the ground. In recent years, from the viewpoint of effective use of land, the recent construction method has been required to be improved to the deep part compared to the conventional construction method, but under such circumstances, the smooth discharge of the soil dispersion slurry to the ground is Although becoming an increasingly important problem, a great effect can be expected by using the curable filler slurry according to the present invention. Also, a large amount of cutting slime is not generated from the viewpoint of construction waste disposal. Furthermore, there are places in urban areas where construction is only possible during the day due to noise problems. In such a place, when the construction is continued on the next day on the part constructed on the previous day, it is necessary to re-cut the solidified part in order to obtain a solid and improved ground. However, when the injection material slurry of the present invention is used, since the fluidity of the soil dispersion slurry is maintained, it is not necessary to newly cut the slurry, and it is possible to work continuously and efficiently. The present invention has been made to provide these features and to provide a method for constructing a solid improved ground reinforced in soft ground.

In the method of the present invention, the multi-tube can be used by pulling it up without rotating the multi-tube. That is, by raising the high-pressure hardening material slurry and the high-pressure air in one direction from the tip of the multi-pipe while pulling up, the soil dispersion slurry comprising the hardening material slurry and the shaved soil is removed. However, it can be solidified into a vertical flat plate shape in soft ground, and a vertical flat plate can be formed in the ground. Similarly, if a multi-pipe having a plurality of injection holes for the curable injection material slurry and air at the tip of the multi-pipe is used, the same operation can be performed without rotating the multi-pipe, so that it can be installed in the ground. At the same time, several vertical flat plates can be formed. The cured body constructed by these,
It can be used as a water stop wall or a structural block.

Continuation of the front page (56) References JP-A-59-25877 (JP, A) JP-A-2-293363 (JP, A) JP-A-60-135478 (JP, A) JP-B-55-35531 (JP, A) , B2)

Claims (1)

(57) [Claims] 1. A pressure-resistant multi-tube having a liquid outlet and an air outlet at the tip side surface is inserted into an existing hole in the soft ground, and the multi-tube is rotated around an axis. A high-pressure hardening injection material slurry is fed into the inside of the multi-tube, and high-pressure air is sent to the outside of the multi-pipe to scrape off the soil in the ground, and the multi-tube is gradually pulled up to initially penetrate. The space around the multi-pipe extending from the end of the multi-pipe, which has been cut, to a desired lifting height, is filled with a soil dispersion slurry composed of the hardenable injection material slurry and the shaved soil, and the volume of the shaved soil The soil dispersion slurry and the air having a volume exceeding the limit are discharged to the ground along the outer wall of the multi-pipe and solidified in the soil dispersion slurry filled in the ground. As wood slurry 0 by weight relative to the solid content of the cement and water and a dispersing agent and the dispersing agent.
A method of strengthening soft ground, comprising using a curable injectable slurry containing a gluconate as a setting retarder in an amount of 02 to 2.00 times.