JP2000087023A - Dispersing agent for excavation slurry and excavation slurry using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dispersing agent which give slurry having wall-making property from a granule ingredient alone of excavated soil without requiring a slurry-making material by composing it of a poly(meth)acrylate salt (copolymer) and specifying its wt. average mol.wt. SOLUTION: A poly(meth)acrylate salt (copolymer) has a wt. average mol.wt. of 10,000-14,000 and is preferably a monovalent salt (e.g. a sodium salt). The poly(meth)acrylate salt (copolymer) having a wt. average mol.wt. of 10,000-14,000 and soil constituted of a granule ingredient, preferably not larger than 10μm are compounded to form excavation slurry. This excavation slurry can maintain its low viscosity owing to the high dispersing function of the dispersing agent even if the specific gravity of the slurry becomes high, resulting in improvement of excavation efficiency, transportation efficiency and soil-sand separation efficiency. Besides, as the excavation slurry is not deteriorated, occurrence of a large amount of waste sludge is prevented even when it is circulatively used in an underground continuous wall method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for drilling mud used in a mud construction method such as a mud shield construction method and an underground continuous wall method, and a drilling mud using the same.

[0002]

2. Description of the Related Art In a muddy water method such as a muddy water shield method and an underground continuous wall method, a face and a groove wall are stabilized by making use of the wall forming property of the muddy water, and the excavated waste is transported in slurry with the muddy water. After the excavated waste is separated and removed from the surface, it is returned to the face and the groove wall side again and used for circulation.

[0003] As described above, the drilling mud used in the muddy water method is basically required to have good wall-forming properties to stabilize the face and the groove wall, and is required to be used for slurry transportation and the like. In view of the above, it is desirable that the low viscosity is maintained within a range in which liquid leakage is prevented. In addition, the underground diaphragm wall method is required to have cement resistance.

In order to satisfy such a function, drilling mud using a bentonite, CMC, dispersant, polymer agent or the like as a mud making material has been widely used. Such mud for drilling, because bentonite and the like are well dispersed in the muddy water,
It is possible to form a good mud cake on the face and the groove wall while maintaining low viscosity, and it is possible to secure the waterproofness and, consequently, the stability of the face and the groove wall by the mud cake.

[0005]

However, in such a drilling mud, bentonite, CMC or a polymer agent is essentially required as a mud making material. Therefore, when the construction scale is large, a large amount of mud is required. The mud cultivation material must be procured in an amount corresponding to the amount of the material, and a problem has arisen in that a mud cultivation plant and a stock yard according to the construction scale must be installed at the site.

[0006] In the underground continuous wall method, calcium ions from concrete significantly reduce the dispersibility of bentonite and clay colloid during repeated use, resulting in an increase in viscosity and a decrease in wall-forming properties. . Therefore, for so-called degraded mud with reduced dispersibility, dispersibility can be recovered by appropriately adding sodium carbonate or the like, and recycling can be achieved. However, as the amount of addition increases, conversely salt aggregation occurs. However, there is a limit to reusing and using degraded mud, and eventually, a large amount of degraded mud must be disposed of, and new mud must be prepared and replenished as needed using the above-mentioned mud-making materials. Had also occurred.

[0007] The present invention has been made in view of the above-mentioned circumstances, and it is possible to produce a drilling mud using only existing materials on site without the need for mud-making materials such as bentonite, CMC, and a polymer agent. An object of the present invention is to provide a dispersant for drilling mud and a drilling mud using the same.

[0008]

In order to achieve the above object, a dispersant for drilling mud according to the present invention is a polyacrylate, a polymethacrylate or a copolymer thereof, as described in claim 1. And having a weight average molecular weight Mw of 10,000 to 14,000.

Further, the dispersant for drilling mud according to the present invention comprises:
The polyacrylate, polymethacrylate or a copolymer thereof is a monovalent salt.

[0010] The drilling mud according to the present invention is claimed in claim 3.
As described in above, a polyacrylate, a polymethacrylate or a copolymer thereof, which includes a dispersant for drilling mud having a weight average molecular weight Mw of 10,000 to 14,000, and a soil composed of fine particles. .

In the muddy water for excavation according to the present invention, the fine particles are set to 10 μm or less.

In the excavating mud dispersant according to the present invention and the excavating mud using the same, the excavating mud dispersant of the present invention remarkably disperses the fine particles of the soil, and disperses the fine particles of the dispersed soil. In place of conventional bentonite, a high quality mud cake having a small amount of drainage (permeability) is formed on a face or a groove wall to stabilize the face. Therefore, muddy water having the functions required for the muddy water method can be produced as long as the dispersant for excavated muddy water of the present invention and fine particles of excavated soil are present.

Further, even when the specific gravity of the muddy water is increased, the low viscosity is maintained by the high dispersing action of the dispersant for drilling muddy water of the present invention, so that the burden on pumps and the like in lifting mud, slurry transportation or sediment separation is reduced. As a result, the excavation efficiency, transportation efficiency or sediment separation efficiency is improved, and as a result, the efficiency of the entire excavation system is greatly improved.

Further, conventionally, when used in the underground continuous wall construction method, calcium ions from cement aggregate bentonite and the like, resulting in a decrease in dispersibility and, consequently, a decrease in wall buildability and an increase in viscosity. However, in the dispersant for drilling mud of the present invention, the dispersing performance itself is higher than the conventional one, and the dispersant for drilling mud of the present invention reacts with calcium ions. Since it has a function to lose its activity, the dispersibility of fine particles does not decrease even when used in the underground continuous wall construction method, and the muddy water function does not deteriorate. Therefore, a large amount of waste mud does not occur as in the related art.

The method of using the dispersing agent for drilling mud according to the present invention includes, as well as the use of the mud for excavation of the present invention, which is mixed with fine particles of soil and water, and the dispersing agent for regenerating the degraded mud. It can also be used as an agent.

Here, the deteriorated muddy water includes not only a conventional muddy water using bentonite or the like but also a drilling muddy water according to the present invention. That is, even when the muddy water for excavation according to the present invention is used, salt aggregation by calcium ions as described above may slightly occur depending on concrete or soil. However, even in this case, if the dispersant for drilling mud of the present invention is replenished and added, the activity of calcium ions can be reduced and the dispersibility can be restored as described above.

In order to restore the dispersibility of the degraded mud,
Conventionally, sodium carbonate has often been used, but the adverse effect of salt coagulation that occurs when such an agent is excessively added does not occur in the dispersant for drilling muddy water of the present invention, and thus, without fear of salt coagulation, The dispersant for drilling mud of the present invention can be added in a desired amount.

The drilling mud dispersant according to the present invention may be composed solely of polyacrylate or polymethacrylate, or may be composed of a copolymer thereof. Further, these copolymers may be used in combination. Here, their weight average molecular weight Mw is 10,000 to 14
The reason for setting the value to 000 was that it was confirmed by experiments that within the above range, the function of muddy water could be achieved only by fine particles of soil particles without using bentonite or the like. Incidentally, the weight average molecular weight Mw is determined by gel permeation chromatography (GPC) based on polystyrene.

As described in the prior art, it is necessary to add bentonite, CMC, a polymer agent, etc. to the muddy water in order to secure the wall-forming property enough to stabilize the groove wall and the face. Although it was common knowledge of those skilled in the art, the present invention focuses on whether it is possible to obtain muddy water function using only excavated soil at the site without using bentonite etc. As a result of repetition of the experiment described above, the molecular weight range described above was identified as a result thereof, and it should be noted that such a molecular weight range cannot be easily adopted by those skilled in the art.

When the weight average molecular weight Mw is in the above range, the fine particles of the soil particles can be remarkably dispersed, but the above-mentioned polyacrylate, polymethacrylate or a copolymer thereof is particularly preferred. If a monovalent salt such as an alkali metal salt such as a sodium salt, a potassium salt, or a lithium salt or an ammonium salt is used, the function as a stabilizer can be reliably obtained with a small amount of addition.

The fine fraction of the soil is generally 75 μm or less, which is mainly composed of clay and silt. However, if the fine fraction of 10 μm or less mainly composed of clay is used, the wall can be formed. Muddy water with excellent properties can be obtained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a drilling mud dispersant according to the present invention and a drilling mud using the same will be described below with reference to the accompanying drawings. It is to be noted that the same reference numerals are given to components and the like that are substantially the same as those in the conventional technology, and description thereof will be omitted.

FIG. 1 is a chemical structural formula showing a dispersant for drilling mud according to this embodiment. As can be seen from the figure, the dispersant 1 for drilling mud of the present embodiment is made of a sodium salt of polyacrylic acid, and has a weight average molecular weight Mw of 100.
00 to 14000.

To prepare the drilling mud of the present embodiment using the drilling mud dispersant 1 of the present embodiment,
It is mixed with water together with a fine particle of 10 μm or less mainly composed of clay. As the water containing such fine particles, specifically, the specific gravity of the decanter over mud or waste mud used in the sediment separation step of the muddy water method such as the shield method or the underground continuous wall method is adjusted as necessary. Can be used. It is preferable to procure such muddy water from another site at the start of the construction, and to use the decanter over muddy water generated at the construction site after the start of the construction.

When the drilling mud of the present embodiment thus produced is used as a stabilizing solution for the shield method or the diaphragm wall method, the excavating mud dispersant 1 remarkably disperses fine particles of 10 μm or less. The fine particles replace the conventional bentonite and the like, and form a high-quality mud cake having a small amount of drainage (permeability) on the face and the groove wall to stabilize the face and the like.

FIG. 2A shows that the weight average molecular weight Mw is 113
The dispersant 1 for drilling mud is set to 00
0 and the weight% aqueous solution, 8 kg per mud 1 m ³ of this
It is the graph which showed the wall formation property of the mud for excavation of this embodiment which is added, and also shows the case where the dispersant is not added. Here, the wall-forming property in the figure is slightly different from the index in the API standard, and the drainage amount when the lower side of the filter paper is depressurized in order to accelerate the drainage process and shorten the experiment time. And 5 ml or less is a measure of good wall-forming properties. In the following, unless otherwise specified, the dispersing agent for drilling muddy water 1
Is used as a 40% by weight aqueous solution, and the amount of addition is {(M / V) / 10} when the mud volume is V (m ³ ) and the addition weight is M (kg). It shall be expressed as%. For example, 0.8% is 1 m ^{3 of} muddy water.
8 kg was added per unit.

From the figure, it can be seen that muddy water (black circles) consisting only of fine particles cannot ensure good wall-forming properties.
It can be seen that in the muddy water for excavation of this embodiment to which 8% of the dispersant 1 for excavated muddy water is added, good wall-forming properties can be secured in a region where the specific gravity exceeds 1.05.

FIGS. 2 (b) and 2 (c) show the case where the dispersant for drilling mud is not added and the dispersant 1 for drilling mud (the weight average molecular weight Mw is 11300, which is the same as that described above) is 0.2%.
3 is a graph showing the funnel viscosity (Fv) and the B type (Brookfield type) viscosity (Bv) when%, 0.4%, 0.6%, and 0.8% are added, respectively.

From these figures, it can be seen that when a certain amount of the dispersant 1 for drilling mud of the present embodiment is added, particularly when 0.4% or more is added, the viscosity is maintained low even if the specific gravity of the mud becomes high. You can see that it is. In addition, as the addition amount of the excavating muddy water dispersant 1 increases, the viscosity becomes lower, but even if it exceeds 3%, the effect corresponding to the addition amount cannot be obtained.

FIGS. 3 and 4 show the relationship between the weight average molecular weight Mw and the viscosity of the dispersant 1 for drilling mud according to the present embodiment.
If the cement is not added and the muddy water 1m ³ per 2
It is the graph each shown about the case where 0 kg of cement was added. Here, the specific gravity of the muddy water is set to 1.115, respectively.

From these figures, it can be seen that the weight average molecular weight Mw is 1
It can be seen that when it is 0000 to 14000, low viscosity can be realized. The fact that such a low viscosity can be realized under the above specific gravity means that the fine particles having a particle size of 10 μm or less have high dispersibility and, consequently, good wall-forming properties.

As described above, according to the dispersing agent for drilling mud according to the present embodiment and the drilling mud using the same, fine particles of 10 μm or less, which are remarkably dispersed in the mud, are generated at the face and groove wall. Bentonite, CM which has been indispensable in the past because it forms a high quality mud cake and stabilizes the face
Even if mud making materials such as C and a polymer agent are not used, muddy water having wall-forming properties required for the muddy water method can be produced as long as the dispersant 1 for excavated muddy water and fine particles of excavated soil are present.

Therefore, it is possible to effectively use the excavated soil as a mud material. Also, in the case of bentonite etc., a kneading mixer for stirring and mixing was required,
The dispersant 1 for drilling mud which can be used as an aqueous solution eliminates the need for a kneading mixer, and in combination with the above-mentioned excavated soil itself becoming mud material, a plant or stock yard for storing and stirring mud material is required. It is possible to greatly reduce or omit, and it is also possible to significantly reduce the mud making time.

Further, as shown in FIG. 2, even if the specific gravity of the muddy water is increased, the low viscosity is maintained, so that the load on a pump or the like in lifting mud, slurry transportation or sediment separation is reduced, and the excavation efficiency, Transport efficiency or sediment separation efficiency is improved. That is, when the excavated soil is mixed into the muddy water with the excavation work, conventionally, the viscosity also increases with the increase in the specific gravity of the muddy water, and the increase in the viscosity increases the load on the mud pump and the slurry pump, Alternatively, since the friction in the transport pipe is increased, the excavation speed has to be suppressed. However, according to the excavation mud using the excavating mud dispersant 1 according to the present embodiment, the specific gravity of the mud is increased. However, since the low viscosity is maintained, the excavation speed can be set high, and the muddy water having a high specific gravity of fine particles can be driven into the decanter, so that the sediment separation efficiency in the decanter also increases. Thus, according to the muddy water for excavation according to the present embodiment, the entire excavation efficiency can be greatly improved regardless of the shield method or the underground continuous wall method. In addition,
In the underground diaphragm wall method, if the concrete is replaced with low-density mud only when necessary, even if the specific gravity of mud increases during excavation, there will be no hindrance to the replacement work with concrete. Does not occur.

In the case where muddy water is circulated and used by the underground continuous wall method, conventionally, bentonite or the like is agglomerated by calcium ions from cement, and the dispersibility of the bentonite and the like is reduced. However, according to the drilling mud dispersant 1 of the present embodiment, the dispersion performance itself is higher than the conventional mud, and the drilling mud dispersant 1 reacts with calcium ions. Since it has a function of losing its activity, even if it is recycled, the dispersibility does not decrease, and so-called muddy water deterioration does not occur. Therefore, it is possible to prevent a situation in which a large amount of waste mud is generated as in the related art, and accordingly, it is possible to reduce waste disposal costs.

In the present embodiment, it is assumed that the dispersing agent 1 for drilling mud is used for preparing a new mud for drilling. However, the dispersing agent 1 is also used as a dispersing agent for regenerating degraded mud. can do. In other words, when the conventional mud using bentonite or the like is deteriorated due to circulating use, the aggregated bentonite or the like is dispersed by adding the dispersant 1 for drilling mud to recover the function as a stable liquid. be able to. In addition, the drilling mud according to the present embodiment is unlikely to cause salt aggregation due to calcium ions as described above, but when the dispersibility is reduced due to repeated use or other reasons, in order to recover the dispersibility. Needless to say, the dispersant 1 for drilling mud may be added to the mud for drilling of the present embodiment.

Incidentally, sodium carbonate has conventionally been often used to recover the dispersibility of the degraded muddy water. However, when such a chemical is excessively added, salt aggregation occurs as shown in FIG. Although there is a limit to the regeneration of the degraded muddy water, there is a limit to regenerating the degraded muddy water. However, as can be seen from FIG. No decrease in wall properties is observed.
Therefore, according to the dispersant 1 for drilling muddy water according to the present embodiment, it is possible to regenerate the degraded muddy water by adding a desired amount thereof without worrying about salt aggregation.

In the present embodiment, the dispersant 1 for drilling muddy water is composed of a sodium salt of polyacrylic acid, but instead of this, a monovalent salt such as an alkali metal salt such as a potassium salt or a lithium salt or an ammonium salt is used. It may be. FIG.
Is an experimental result of examining the influence of the terminal group of the polyacrylate, and it can be seen that good low viscosity is maintained with respect to the above-mentioned monovalent salt.

In this embodiment, the dispersant 1 for drilling muddy water is composed of sodium polyacrylate, but instead of sodium polyacrylate, sodium polymethacrylate or a copolymer thereof is used. The same operation and effect as described in the embodiment can be obtained.

[0040]

As described above, according to the dispersing agent for drilling mud and the drilling mud using the same according to the present invention, it is possible to use a conventional mud-forming material such as bentonite, which is indispensable.
As long as there is only fine particles of the excavated soil, muddy water having wall forming properties required for the muddy water method can be produced. Therefore, the excavated soil can be effectively used as mud material, and a plant and a stock yard for storing and stirring the mud material can be significantly reduced or omitted. The time can be significantly reduced.

Further, since the low viscosity is maintained even when the specific gravity of the muddy water is increased, the burden on pumps and the like in mud lifting, slurry transport or sediment separation is reduced, and excavation efficiency, transport efficiency, or sediment separation efficiency is improved. .

Also, even in the case of circulating use by the underground continuous wall construction method, the muddy water for excavation of the present invention does not deteriorate, so that it is possible to prevent a situation in which a large amount of waste muddy water is generated unlike in the prior art. It becomes possible.

Further, according to the dispersant for drilling mud according to the second aspect of the present invention, there is also an effect that a function as a stable liquid can be reliably obtained with a small amount of addition.

According to the muddy water for excavation of the present invention according to claim 4, there is also an effect that muddy water having excellent wall-forming properties can be obtained.

[0045]

[Brief description of the drawings]

FIG. 1 is a chemical structural formula showing a dispersant for drilling mud according to the present embodiment.

FIG. 2 is a graph showing the action of drilling mud using the drilling mud dispersant according to the present embodiment, where (a) is a wall-forming property,
(b) is a graph showing the funnel viscosity, and (c) is a graph showing the B-type viscosity.

FIG. 3 is a graph showing the relationship between the molecular weight and the viscosity of the dispersant for drilling mud according to the present embodiment.

FIG. 4 is a graph showing the relationship between the molecular weight and the viscosity of the dispersant for drilling mud according to the embodiment.

FIG. 5 is a graph showing a regeneration effect on degraded muddy water.

FIG. 6 is a graph showing the influence of a terminal group.

[Explanation of symbols]

 1 Dispersant for drilling mud

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Kawaji 4-640 Shimoseito, Kiyose-shi, Tokyo Inside the Obayashi-gumi Technical Research Institute Co., Ltd. (72) Inventor Yoshio Tanimizu Sanyo Kasei Kogyo Co., Ltd., 1-11, Hitotsubashi Nohoncho, Higashiyama-ku, Kyoto, Kyoto Prefecture (72) Inventor Fumiaki Motofuji 1-11, Hitotsubashi Nohoncho, Higashiyama-ku, Kyoto, Kyoto Sanyo Chemical Co., Ltd. (72) Inventor Yuka Adachi 1-1-1, Hitotsubashi-Honcho, Higashiyama-ku, Kyoto, Kyoto F-term (reference) 2D049 GA03 GC05 2D054 AC05

Claims (4)

[Claims] 1. A polyacrylate, a polymethacrylate or a copolymer thereof, having a weight average molecular weight M
A dispersant for drilling mud, wherein w is 10,000 to 14,000. 2. The polyacrylate, polymethacrylate or a copolymer thereof is a monovalent salt.
A dispersant for drilling mud as described in the above. 3. A polyacrylate, a polymethacrylate or a copolymer thereof, having a weight average molecular weight Mw.
Characterized by comprising a dispersant for drilling mud having a particle size of 10,000 to 14000, and soil composed of fine particles. 4. The muddy water for drilling according to claim 3, wherein the fine particle content is 10 μm or less.