JP2832689B2 - Ground improvement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injecting cement slurry in which water is mixed with cement into a ground and using the mixed cement to solidify the ground. It relates to improved construction methods.

[0002]

2. Description of the Related Art It is difficult to uniformly mix a cement slurry and soil particles in a viscous ground. For this reason, in the related art, a method of sufficiently spending time when stirring the clay particles and the cement slurry with the stirring blade, a method of attaching the viscous soil co-rotation prevention blade to the stirring blade, and a method of rotating the rotation in the normal rotation A method of stirring with a stirring blade is used.

[0003]

However, of the above-mentioned conventional examples, the first method requires a long construction time. If the stirring blade is rotated at a high speed in order to shorten the construction time, the stirring blade may be damaged. On the other hand, in the second and third methods, since the structure of the apparatus is complicated, there is a possibility that the cost may be increased or stirring may be hindered.

[0004] In view of the above situation, the present inventors have
As a result of various tests and studies, it was found that by adding a cement water reducing agent to the cement slurry and mixing with the clay, the strength of the ground was improved with a shorter stirring time than in the case of no addition. This is presumed that the cement water reducing agent is excellent in the effect of dispersing the cement particles, so that the viscosity can be reduced even for the clay particles and the dispersing effect can be obtained.
And it was found that the ground strength was improved in a shorter time by using the cement water reducing agent in combination with the foaming agent. This is due to the fact that mixing becomes easier due to the effect of the bubbles on the clay particles as a bearing, the viscosity of the clay is reduced by the cement water reducing agent, and these become a surplus effect and can be uniformly mixed in a short time. It is supposed to be. It was also found that such a principle can be applied to soil particles other than clay.

According to the present invention, based on the results of the above test and research, the use of a generally used stirring blade and the use of a generally used stirring blade and a shorter working time and a higher number of times of stirring than the conventional one achieve uniform and high performance. It is an object of the present invention to provide a ground improvement method capable of forming a high-strength consolidated body and thus performing high-quality, low-cost construction.

[0006]

The technical means of the present invention for achieving the above object is to inject a cement slurry into the ground and mix it with the ground to improve the ground. The cement water reducing agent and air bubbles are mixed.

In order to mix the cement slurry containing air bubbles with the ground, the rotating slurry and a stirring blade provided on the rotating rod are made to enter the ground while rotating.
During this time, a cement slurry containing a cement water reducing agent and air bubbles can be injected into the ground from the tip of the rotating rod.

By using the cement water reducing agent in an amount of 10% or less based on the dry weight of the cement and the amount of air bubbles mixed in the cement slurry at 30% to 80%, cement particles and soil particles such as clay are used. Can be mixed uniformly and in a short time, and the strength of the ground can be improved. Therefore, the mixing amount of the cement water reducing agent with respect to the dry weight of the cement can be appropriately selected at 10% or less, particularly preferably 5% or less, and the amount of bubbles mixed into the cement slurry is 30%. ~
It can be appropriately selected within the range of 80%, and particularly, 50%
It is preferable to mix air bubbles finely in the range of up to 70%.

[0009]

According to the present invention, a cement water reducing agent and air bubbles are mixed into a cement slurry and injected into the ground and mixed with the ground, so that cement particles and soil particles are dispersed and the cement particles are uniformly dispersed with the ground. , And can be mixed in a short time to form a high-strength consolidated body.

[0010]

【Example】

(Example 1) For 1600 g of clay having a water content of 50%, cement 200 g, water 140 ml, foaming agent (monocleat, manufactured by Daiichi Kasei Sangyo Co., Ltd .: 1 g), cement containing sodium melamine sulfonate as a main component 4 g of a water reducing agent (Molmaster: trade name, manufactured by Showa Denko KK) was mixed and stirred at 130 rpm per minute by a soil mixer.
At this time, the amount of air bubbles (the amount of air) was about 60% with respect to the cement slurry. The cement slurry containing the cement water reducing agent and the air bubbles was mixed with the clay with a soil mixer for 1 minute, 3 minutes, and 5 minutes to form three test pieces.

Example 2 Oxycarboxylic acid compound,
Three test pieces were stirred in the same mixing ratio as in Example 1 except that 2 g of a cement water reducing agent (Parick A: trade name, manufactured by Fujisawa Pharmaceutical Co., Ltd.) containing a rhodan compound as a main component was used. Was made.

As Comparative Example 1, clay 16 having a water content of 50% was used.
For 200 g of cement, 200 g of cement, 140 ml of water, foaming agent (Monocleet manufactured by Daiichi Kasei Sangyo Co., Ltd .: trade name)
1 g was mixed and stirred at 130 rpm using a soil mixer. At this time, the amount of air bubbles (the amount of air) was about 60% with respect to the cement slurry. The cement slurry mixed with the air bubbles was mixed with the clay with a soil mixer for 1 minute, 3 minutes, and 5 minutes to form three test pieces.

As Comparative Example 2, clay 16 having a water content of 50% was used.
200 g of cement, 140 ml of water, and 4 g of a cement water reducer containing sodium melamine sulfonate (Molmaster: trade name, manufactured by Showa Denko KK) per 00 g
And stirred with a soil mixer at 130 rpm. The cement slurry mixed with the cement water reducing agent was stirred and mixed with the clay for 1 minute, 3 minutes, and 5 minutes using a soil mixer to produce three test pieces.

Comparative Example 3 was the same as Comparative Example 2 except that 2 g of a cement water reducing agent (Parick A: trade name, manufactured by Fujisawa Pharmaceutical Co., Ltd.) containing an oxycarboxylic acid compound and a rhodan compound as main components was used. In the mixing ratio, stir similarly to 3
Test pieces were made.

As Comparative Example 4, clay 16 having a water content of 50% was used.
200 g of cement and 140 ml of water were mixed with 00 g, and the mixture was stirred with a soil mixer at 130 rpm.
The cement slurry containing neither the cement water reducing agent nor the air bubbles was mixed with the clay with a soil mixer for 1 minute, 3 minutes, and 5 minutes to prepare three test pieces.

A cement water reducing agent containing sodium melamine sulfonate as a main component is defined as (1), and a cement water reducing agent mainly containing an oxycarboxylic acid compound or the like is defined as (2).
Table 1 shows the compounding ratios of Examples 1 and 2 and Comparative Examples 1 to 4.

[0017]

[Table 1]

As a result of measuring the compressive strength of each test piece on the 28th day of material, the stirring time was 1 as shown in FIG.
In Examples 1 and 2 of the present invention in which a cement water reducing agent and a foaming agent were used in combination, the amount of the cement water reducing agent and the foaming agent were twice as large as Comparative Example 4 in which neither the cement water reducing agent nor the foaming agent was used. 1.3 or more of Comparative Examples 1 to 3 using only one of them.
A compression strength of 2 times could be obtained. When the stirring time was 3 minutes, in Examples 1 and 2 of the present invention in which a cement water reducing agent and a foaming agent were used in combination, 1.7% to 1% of Comparative Example 4 in which neither the cement water reducing agent nor the foaming agent was used. The compressive strength was 0.8 times, 1.4 times that of Comparative Examples 1 to 3 using only one of the cement water reducing agent and the foaming agent. When the stirring time is 5 minutes, in Examples 1 and 2 of the present invention in which a cement water reducing agent and a foaming agent are used in combination, 1.6 to 1.6 of Comparative Example 4 in which neither a cement water reducing agent nor a foaming agent is used.
1.7 times, 1.2 to 1.4 times the compressive strength of Comparative Examples 1 to 3 using only one of the cement water reducing agent and the foaming agent could be obtained.

As is clear from these test results, it was found that by using the cement water reducing agent and the foaming agent together and mixing the cement slurry with the ground, high strength of the consolidated body can be obtained with a short stirring time. Was.

[0020]

As described above, according to the present invention, a cement water reducing agent and air bubbles are mixed into a cement slurry and injected into the ground and mixed with the ground, so that cement particles and soil particles are dispersed, The cement particles can be uniformly mixed with the ground in a short time to form a high-strength consolidated body. Therefore, high quality and low cost construction can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between a stirring time and a compressive strength of a test piece manufactured by a ground improvement method according to an embodiment of the present invention and a comparative example.

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Claims (2)

(57) [Claims] 1. A method for injecting a cement slurry into ground and mixing it with the ground to improve the ground, wherein a cement water reducing agent and air bubbles are mixed into the cement slurry, and the cement water reducing agent is mixed with the cement dry weight. A ground improvement method, wherein the amount is 10% or less and the amount of the bubbles mixed with the cement slurry is 30% to 80%. 2. A rotating rod and a stirring blade provided on the rotating rod are made to enter the ground while rotating, and during this time,
The ground improvement method according to claim 1, wherein a cement slurry containing a cement water reducing agent and air bubbles is injected into the ground from the tip of the rotating rod.