JP2010248759A - High specific gravity slurry and excavation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of conventional constructions wherein though the slurries used in various excavation methods require a specific gravity of 1.10 or below, a proper viscosity, a wall building property and large frost resistance and cement resistance, in recent constructions such as a deep underground excavation construction, conventional slurries are difficult to adapt to the treatment of large soil pressure and large water pressure, and the risk of falling increases, and though the addition of CMC for increasing the viscosity of the conventional slurries and the addition of a compound for further increasing the viscosity thereof are proposed, the lowering of flow property is pointed out, and the securement of the slurries used in the deep underground excavation method is difficult. <P>SOLUTION: A slurry with a specific gravity of 1.01-3.0 is provided by mixing the magnetic substance which can provide a sufficiently high specific gravity and can be attracted by a magnetic force. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high specific gravity stabilizing liquid and an excavation method.

In various excavation methods in recent years, protection of excavated wall surfaces is extremely important. This is because stabilization of the wall surface, that is, prevention of wall collapse, water loss, etc. is greatly related to the progress of various constructions such as earth excavation method, pile method, mud shield method, pouring method, deep excavation method, etc. .
For this reason, in the excavation method, a method is often used in which a stable liquid is poured into the excavation surface, the liquid is infiltrated into the wall surface, and bentonite or the like that is added to the wall surface by the water pressure is deposited in soil particles. .

  Further, this stabilizing liquid is used for transporting excavated soil to the ground in a circulation excavation method or the like. The technology for producing earth retaining in the basement is to mix bentonite, water and dispersing agent during earth retaining excavation, and to pour the stable liquid produced to a stable liquid specific gravity of about 1.03 to 1.1 into the excavated ground. A retaining wall was formed.

Currently used stabilizers are required to have a specific gravity of 1.10 or less, appropriate viscosity and wall-forming properties, high salt and cement resistance, and good replacement with concrete.
For this reason, as a stabilizer used in the civil engineering construction direction, generally, a bentonite of 2 to 8 parts by weight and a CMC of 0.05 to 0.5 parts by weight are used with respect to 100 parts by weight of fresh water.

JP-A-9-302143 JP 2005-36144 A JP 7-316554 A JP 2001-240852 A

In this conventional general stabilizing liquid, the specific gravity is as small as 1.03 to 1.1. Therefore, it collapses or collapses when excavating deep soil or excavating under high-pressure groundwater conditions. The danger was great. When excavating such ground, it has been necessary that the stable hydraulic pressure exceeds the water pressure by about 0.1 to 0.3 kgf / cm ² .

  In addition, conventional stabilizers need to be transported as a solution when discarded after use, and because stabilizers containing bentonite are designated as industrial waste, it is difficult to treat as a pollutant. The transportation and disposal costs are expensive.

  Conventionally, as an attempt to obtain a high specific gravity, for example, there are proposals for blending bentonite, kaolin mineral, etc. as clay minerals, or blending CMC, anionic water-soluble polymer, acrylamide polymer, etc. as thickeners. Has been.

However, these compounds are difficult to use as a weight-increasing material while having effective properties such as being resistant to spoilage, non-toxicity, and excellent drainage. There were difficulties and there was no practicality.
In addition, barium sulfate used as a heavier for oil drilling mud becomes easy to separate over time, and it is difficult to ensure stability.

  Therefore, in the present invention, a stable liquid having a large specific gravity is manufactured to form a strong mud film corresponding to deep excavation and high-pressure geological excavation, which has been difficult in the past, and to reduce excavated soil pollution. For the purpose. For this reason, first, it is necessary to produce a stable liquid having a large specific gravity at a low cost, and then to produce a stable liquid without using as much bentonite as possible to cause pollution.

  However, if the specific gravity is increased, the particles are easily settled and separated, and the effect of the stabilizing solution is lost. Therefore, a method for floating in the solution for a certain period is required.

  Furthermore, in selecting a substance having a large specific gravity, it is important that the cost can be prevented by collecting the used substance and using it many times.

In order to solve the above problems, the present invention uses a substance having a higher specific gravity than conventional materials, a ferrosilicon (hereinafter referred to as Fs), a magnetic substance such as iron powder as a main material of the stabilizing liquid, Produced and used, and at the time of discarding the stable liquid, the discharged liquid is separated into the main material Fs and the residue by magnetic force, and the main material Fs is adsorbed and recovered.
First, it is a stable liquid used in excavation methods and the like, and a magnetic material that can be adsorbed by magnetic force is mixed, and the stable liquid specific gravity is maintained at 1.01 to 3.0,
Second, the magnetic material that can be adsorbed by magnetic force is iron powder,
Third, the magnetic material that can be adsorbed by magnetic force is ferroalloy,
Fourth, the magnetic material that can be adsorbed by magnetic force is ferrosilicon,
Fifth, it is a stable liquid used in the excavation method, and contains magnetic material characterized by containing ferrosilicon or iron powder 1000 kg to 3000 kg, water 500 kg to 1000 kg, polymer 1 to 5 kg with respect to the mixed amount 1 m ³ . The magnetic substance that can be adsorbed is iron powder that is ferroalloy,
Sixth, the particle size of the component used in the stabilizing liquid is characterized by containing 50% or more of particles having a diameter of 100 μm or less and 50 μm or less,
Seventh, it is a high-specific gravity stable liquid characterized in that the viscosity of the stable liquid is 3000 mPas or less.
Eighth, the high specific gravity stabilizing liquid is supplied into the excavation hole, and excavation work is performed.
Ninth, the magnetic substance that can be adsorbed by the magnetic force in the stable liquid is recovered by the magnetic force and used repeatedly,
Tenth, the used stabilizing liquid is an excavation method characterized in that a magnetic substance is adsorbed by a rotating drum and separated from other earth and sand mixture.

  According to the first aspect of the present invention, a stable liquid having a very high specific gravity can be obtained. Thereby, a strong mud film can be formed on the excavation wall surface in the excavation part or the like. For this reason, accidents such as collapsing and sliding are sufficiently prevented in response to the large earth pressure and large water pressure encountered in various excavation methods frequently used in deep underground development, infrastructure development, construction, etc., and it plays a role as a stabilizing liquid It has a function that can be performed sufficiently.

  According to claims 2, 3, 4 and 5, since a material that can be adsorbed by magnetic force is used as a weight-increasing material, once the solution is used, the magnetic material can be recovered and repeatedly used later. The recovery rate is good, and an extremely economical stabilizer can be provided.

  According to the sixth and seventh aspects, separation and settling of suspended particles can be prevented by this particle size, the suspended particles can be suspended for a desired period of time, and the action of the stable liquid can be maintained for a long period of time.

  According to claim 8, in various excavation methods and the like, the formation of a thin and strong mud film on the excavation wall surface and the like causes severe conditions such as large earth pressure, deep underground work that causes large water pressure, and severe groundwater conditions. Prevents underground collapse in new construction, and can achieve a stable construction method.

As described above, the method of the present invention can be used for various methods such as earth retaining excavation method, pile method, mud shield method, pouring method, deep excavation method, specific gravity separation method for excavated material.
Further, according to this method, although depending on the particle diameter, iron content, etc., about 90% of the Fs amount in the stable liquid can be adsorbed by magnetic force. For this reason, there is an effect that the amount of residue of the discharged matter is small, the amount of transport is small, the bentonite liquid is not transported, the cost is low, and the pollution is low.

  According to the ninth aspect, an expensive magnetic material can be used repeatedly, and the cost of the stable liquid can be reduced.

  According to the tenth aspect, the earth and sand mixture and the magnetic material can be separated very easily, and the cost of the stable liquid can be reduced.

As a substance having a high specific gravity used in the present invention, a magnetic substance such as ferroalloy, especially ferrosilicon, iron powder is used.
As a substance having a high specific gravity, Fs containing iron is used. After use, Fs is magnetically adsorbed, Fs is obtained, and the residue is discarded. In order to float particles with a large specific gravity in the liquid for a long time, the stable liquid basically reduces the particle size, increases the viscosity, and reduces the difference between the specific gravity of the particle and the stable liquid based on Stokes' theorem. By doing so, the optimum values of liquid specific gravity, liquid viscosity, particle specific gravity, particle size and auxiliary agent are determined.

  When producing a stable liquid having a desired liquid specific gravity, there is a problem of preventing separation and settling of suspended particles. Sedimentation becomes faster as the specific gravity of ferrosilicon or the like increases. It is necessary to float the particles for a desired period of time to prevent settling. Airborne particles are expensive and must be collected. In order to widen the application range of the stabilizer, it is necessary to produce a stabilizer having a specific gravity as large as possible.

The Fs specific gravity is selected by using a stabilizing solution. Fs standard, FeSi45, density 5.1 g / cm ³ , FeSi75, density 2.8, etc. are usually used. In order to increase the stable liquid specific gravity, the Fs particle specific gravity must be large, and not only that, but also the particles with large specific gravity will not settle in the liquid or be slow. Therefore, it is desirable that the difference between the particle specific gravity and the pseudo liquid specific gravity is small, and that the viscosity of the stable liquid is small as long as it can be applied.

In FIG. 3, when the viscosity J is on the y-axis and the liquid specific gravity K is on the x-axis, the relational expression y = 2612.8x−4902.5 is established. At this time, the determination coefficient R ² = 0.7933. This relationship diagram is shown in FIG.

In FIG. 4, when the viscosity J is on the y-axis and the particle size M is on the x-axis, the relational expression y = −128.74x + 10607 is established. At this time, the determination coefficient R ² = 0.6138. This relationship is shown in FIG.

  As shown in the relationship diagrams of FIGS. 3 and 4, in order to obtain a liquid specific gravity of 3.0, the liquid viscosity is desirably 4000 mPas or less, and as shown in the relationship diagram of FIG. 4, the particle diameter is desirably 60 μm or less. For a liquid specific gravity of 2.0, a viscosity of 100 mPas or more and a particle size of 100 μm or less is desirable. Within this range, it is possible to produce a stable liquid in which particles do not settle for a necessary period.

FIG. 1 is an example showing the loss on drying depending on the concentration of the bentonite solution. In the figure, A is a concentration loss of bentonite solution of 10% and B is a loss of drying diagram of 5%.
Thereby, the lower the solution concentration, the better the dryness, and the remaining amount after use decreases. It has been shown that weight loss can be achieved as a source of pollution.

Next, separation of the ferrosilicon and earth / sand mixture will be described.
FIG. 2 is a schematic diagram of the separation mechanism of Fs and earth and sand mixture. It is convenient to install and use these separation mechanisms in the earth and sand separator used in the stable liquid method. There is a steel drum E in the center, and a magnet is mounted inside the drum E. There is a material charging hopper F at the top. A cutting spatula G is attached to the lower part of the drum E apart from the drum E, and the Fs magnetically attached to the drum E is cut off.

The excavation mixture is charged into the material charging hopper F and flows down along the surface of the drum E. Fs is attracted to the drum E by the magnetic force inside the drum E, and is shaved by the shaving spatula G, and Fs falls to the dropping container I. The residue falls into the dropping container H. In this way, Fs and the residue are separated.
The shaving spatula G can be brought into contact with or separated from the drum E automatically or manually. Further, the contact of the cutting spatula G is conveniently performed during the period when the excavation mixture dropping from the material charging hopper F is stopped, but there is no problem even if the residue is mixed. The residue can be dropped into the dropping container I, scraped from the side to the bottom of the drum E so that the spatula G can be freely contacted and separated, and Fs can be accommodated in the dropping container H.

In order to obtain a stable liquid having a liquid specific gravity of 2.0 viscosity and 200 mPas, a Fs material having a specific gravity of 5.1, a particle size of 100 μm or less, a particle size of 50 μm or less, 50% or more, a mixing amount of 1 m ³ , Fs of 1250 kg, water 746 kg, 2.4 kg of polymer (RB-35), 25 kg of bentonite and (mesh 300) were mixed to produce a stable solution.
The specific gravity of the stabilizer was 2.02, and the viscosity was 153 mPas. The amount of infiltrate after pressurization for 30 minutes with 3 kg / cm ² by a simple pressure gauge was 15.4 ml, ph = 10.5, and the mud cake thickness was 0.43 cm.

  In the stable liquid and particle sedimentation experiment, the sedimentation depth of the container having a diameter of 5 cm, a cylinder having a height of 100 cm, and a liquid specific gravity of 2.0 was 10 cm after 72 hours and 20 cm after 168 hours. As described above, it was confirmed that the specific gravity of the stabilizing liquid was ensured for a long time. For the recovery of Fs after the use of the stabilizing liquid, as shown in FIG. 2, the mixture of the material charging hopper F is magnetically adsorbed by the drum E and falls into the dropping container I, and the residue other than Fs of the mixture is It falls into the drop container H and is separated. A 9000 Gauss magnet was used for magnetic adsorption.

In order to obtain a stable liquid having a liquid specific gravity of 3.0 viscosity and 3000 mPas, the Fs material has a specific gravity of 6.5 and a particle size of 50 μm or less, a mixing amount of 1 m ³ , Fs 2343 kg, water 629 kg, polymer (RB-35) Was mixed with 3.13 kg of bentonite and 31.25 kg of bentonite (mesh 300) to produce a stable liquid.
The specific gravity of the stabilizer was 3.0 and the viscosity was 2950 mPas. The amount of infiltrate after pressurization at 3 kg / cm ² for 30 minutes with a simple pressure gauge was 3.0 ml, ph = 10.5, and the mud cake thickness was 0.36 cm.

  In the stable liquid and particle sedimentation experiment, the sedimentation depth of the container having a diameter of 5 cm, a cylinder having a height of 100 cm, and a liquid specific gravity of 3.0 was 10 cm after 72 hours and 20 cm after 168 hours. As described above, it was confirmed that the specific gravity of the stabilizing liquid was ensured for a long time. The magnetic recovery rate of the Fs mixture was 90%. For the recovery of Fs after the use of the stabilizing liquid, as shown in FIG. 2, the mixture of the material charging hopper F is magnetically adsorbed by the drum E and falls into the dropping container I, and the residue other than Fs of the mixture is It falls into the drop container H and is separated. A 9000 Gauss magnet was used for magnetic adsorption.

FIG. 6 is a graph showing weight loss / drying of bentonite in a stable solution according to an embodiment of the present invention. Schematic of separation mechanism of Fs and earth and sand mixture showing one embodiment of the present invention FIG. 4 is a relationship diagram of viscosity / liquid specific gravity of a stable liquid according to an embodiment of the present invention FIG. 5 is a relationship diagram of viscosity / particle size of a stabilizer according to an embodiment of the present invention.

E Steel drum F Material input hopper G Shaving spatula H Dropping container I Dropping container A 10% bentonite B 5% bentonite C Bentonite weight D Time J Viscosity K Liquid specific gravity L Viscosity / liquid specific gravity M Viscosity / particle diameter

Claims (10)

  A high-specific gravity stable liquid that is used in excavation methods and the like, and that contains a magnetic substance that can be adsorbed by a magnetic force to maintain the specific gravity of the stable liquid at 1.01 to 3.0.   The high specific gravity stabilizing liquid according to claim 1, wherein the magnetic substance that can be adsorbed by magnetic force is iron powder.   The high specific gravity stable liquid according to claim 1, wherein the magnetic substance that can be adsorbed by magnetic force is ferroalloy.   4. The high specific gravity stabilizing liquid according to claim 1, wherein the magnetic substance that can be adsorbed by a magnetic force is ferrosilicon. It is a stable liquid used in the excavation method, and contains ferrosilicon or iron powder 1000 kg to 3000 kg, water 500 kg to 1000 kg, and polymer 1 to 5 kg with respect to the mixed amount 1 m ³ . A high specific gravity stabilizing liquid characterized in that the magnetic substance that can be adsorbed by magnetic force is iron powder that is ferroalloy.   6. The high specific gravity stable liquid according to claim 5, wherein a particle size of a component used in the stable liquid is 100 μm or less at a maximum and contains 50% or more particles having a diameter of 50 μm or less.   7. The high specific gravity stabilizer according to claim 5, wherein the viscosity of the stabilizer is 3000 mPas or less.   An excavation method characterized in that excavation work is performed by supplying the high specific gravity stabilizing liquid according to claim 1 into an excavation hole.   The excavation method according to claim 8, wherein the magnetic substance that can be adsorbed by the magnetic force in the stable liquid is recovered by the magnetic force and repeatedly used. The excavation method according to claim 9, wherein the used stabilizing liquid adsorbs a magnetic substance by a rotating drum and separates it from other earth and sand mixture.

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