Title of Invention	"METHOD FOR GENERATING FOAM FOAM AND FOAMING MATERIAL PREPARED BY THE SAID METHOD"
Abstract	A method for generating foam in the rheological foam shield tunneling method, comprising the steps of adding one selected from the group consisting of carboxymethylcellulose, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa.s with a foaming generator; adding and mixing an aqueous solution of metal ions in the form of a 0.5 to 10% aqueous solution into foam obtained immediately after the generation, with the mixing ratio of aqueous solutions of metal ions to unmixed foam generating solution is 5 to 10% by volume and a forming material prepared by the said method.

Title of Invention

"METHOD FOR GENERATING FOAM FOAM AND FOAMING MATERIAL PREPARED BY THE SAID METHOD"

Abstract

A method for generating foam in the rheological foam shield tunneling method, comprising the steps of adding one selected from the group consisting of carboxymethylcellulose, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa.s with a foaming generator; adding and mixing an aqueous solution of metal ions in the form of a 0.5 to 10% aqueous solution into foam obtained immediately after the generation, with the mixing ratio of aqueous solutions of metal ions to unmixed foam generating solution is 5 to 10% by volume and a forming material prepared by the said method.

Full Text	TECHNICAL FIELD The present invention relates to a method for generating foam and foaming materials suitable for use particularly in a highly permeable gravel layer in the rheological foam shield tunneling method. BACKGROUND ART Mud-making materials currently used in soil pressure balanced shield are categorized as (a) bentonite-based, (b) cellulose-based, (c) polyacrylamide-based, (d) water-absorbing resin-based, and (e) surfactant-based materials. Among these, foaming agents used in the rheological foam shield tunneling method belong to (e) surfactant-based materials and are formed by mixing air into aqueous solution of a special foaming agent (OK-2: a preparation formulated using cellulose macromolecules made from pulp as the main agent of a foam-generating material) . By injecting this foaming material into the excavation face, it is possible to improve the fluidity and watertightness of excavated soil and also to prevent adhesion of excavated soil to the interior walls of the chamber. This enables smooth tunnel excavation while maintaining the face in a stable condition. Further, in the rheological foam shield tunneling method, the type of foaming material is determined based on the properties of the soil be excavated, i.e., the grain size distribution curve, (see technical information on the rheological foam shield tunneling method: "Soil Characteristics and Criteria for Selection of Special Foaming materials," published by the Shield Tunneling Association of Japan, March 2003 [refer to http://www.shield-method.gr.jp/what/kiho.pdf]). For example, as shown in FIG. 1, the applicable range of type A (solution viscosity: 2.7 mPa.s) is zone I or zone II consisting of clay, silt, fine sand, etc., whereas the applicable range of type B (solution viscosity: 300 mPa.s) is zone II to III consisting of fine sand, coarse sand, etc. Type B materials are applicable to zone II to III in that their foam strength has been enhanced by conferring viscosity on foam by adding the viscosity-enhancing agent OK-2 to OK-1. However, in a highly permeable gravel layer, particularly in a type of soil with a large coefficient of permeability, belonging to zone IV, even when type B is used, foam is prone to disappear because of the gush of abundant ground water. This has presented problems such as the unstable condition of the face or soil eruption from the screw conveyor, causing trouble in tunnel driving. Consequently, another additive or supplementary construction method is required to be used in combination . This is because increasing viscosity more than that of the conventional type B causes an increase in the pressure and blocking within the foaming generator that are associated with the increased viscosity. As a result, the foaming ratio is decreased to the extent that 6-fold foam generation, the standard of type B in the rheological foam shield tunneling method, cannot be achieved. The present invention solves the above-mentioned problems. It provides a method for generating foam in the rheological foam shield tunneling method and a foaming material used for the rheological foam shield tunneling method, which enable implementation of the rheological foam shield tunneling method without using any other additive or supplementary construction method even in a highly permeable gravel layer by further increasing viscosity while maintaining the expected foaming ratio using a type B foam-generating material. DISCLOSURE OF THE INVENTION The method for generating foam according to the present invention includes the steps of adding one selected from the group consisting of CMC, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa. s through a foaming generator at the predetermined foaming ratio; and adding and mixing an aqueous solution of metal ions into foam obtained immediately after the generation. In the method of claim 1 according to the present invention, the metal ions are trivalent metal ions or calcium ions. Further, in the method of claim 1 or 2 according to the present invention, an auxiliary agent for pH adjustment has been added to the metal ions. The foaming material used for the rheological foam shield tunneling method according to the present invention is obtained immediately after undergoing the steps of adding one selected from the group consisting of CMC, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; and foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa.s through a foaming generator at the predetermined foaming ratio. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing soil characteristics and the criteria for selection of foam-generating materials. FIG. 2 is illustrative sectional view of the rheological foam shield tunneling method to which the method according to the present invention is applied. BEST MODE FOR CARRYING OUT THE INVENTION FIG. 2 shows the rheological foam shield tunneling method to which the method of the present invention is applied. Referring to the figure, 1 is a shield tunneling machine, and 2 is a tunnel segment constructed behind the tunneling machine 1. The shield tunneling machine 1 includes a cutter disc 4 at the front of a cylindrical skin plate 3, and is configured to excavate the face by rotating the cutter disc 4 while moving forward by exerting reaction force on the front end part of the segment 2 with a jack (not shown in the figure) , to transport, with a screw conveyor 7, excavated muck taken into a chamber 6 defined by a partition wall 5 behind the cutter disk 4, and to transfer the muck to the muck car placed behind the conveyor so that the muck is removed. Inside the tunnel enclosed by the segment 2, behind the tunneling machine 1, are laid conveyor rails 8. In the embodiments of the present invention, various back-up cars constituting the foam-generation plant are linked in a line on these rails 8. The back-up cars consist of, in the order from the last, a foam-generating material tank car 9, a driving car 10, a control car 11, and a foam generation car 12, together with a metal ion tank 13 placed above the foam generation car 12. The tank car 9 provisionally retains the foam-generating material supplied by a foam-generating material pipeline 14' drawn into the tunnel. The driving car 10 is equipped with a foam-generating material injection pump 15 and an air compressor 16. The control car is mounted with a control system 17 for the pump 15 and the compressor 16. The foam generation car 12 is equipped with a foaming generator 18. These cars are linked through the foam-generating material supply line and air line. By driving the plant, the foam-generating material retained in the tank car 9 is transferred to the foam generator 18 by the pump 15. By mixing the pressure air produced by the air compressor 16 within the foam generator 18 at the predetermined pressure ratio, the foam-generating material is discharged to the front of the cutter disc 4 through the foam injection pipe 19. Further, near the discharge end of the foam generator 18 in the foam injection pipe 19, which is connected to the metal ion tank 13 through a supply pipe 20 and a pump P, metal ion solution is mixed into the foam generated within the foam generator 18. The mixing ratio is set to the predetermined ratio by controlling the drive of the pump P by the aforementioned control system 17. In the above-mentioned plant, the foam-generating material to be used is a type B foam-generating material complying with the aforementioned zones II to III. This foam-generating material is a foam-generating solution that contains as the main components, in addition to the above-mentioned OK-1, which is the main component of the foam-generating material, one selected from the group consisting of CMC, guar gum, and alginic acid, or their mixture . The viscosity of the foam-generating solution is adjusted to 300 to 500 mPa.s. CMC, guar gum, and alginic acid, or their mixture to be added is gelatinized in the presence of trivalent metal ions or calcium ions, whereby its viscosity is increased, e.g., 2 to 40-fold. Thus, in the present invention, viscosity of foam is increased, while maintaining the foaming ratio at the expected ratio, by mixing metal ion solution into the foam, and this highly-viscous foam is provided at the front of the cutter disc 4. As a result, smooth excavation is possible without using any other additive or supplementary construction method even in a highly permeable gravel layer, i.e., a type of soil with a large coefficient of permeability belonging to zone IV. In addition, plastic fluidity and watertightness is improved, whereby soil eruption from the screw conveyer can be prevented. Examples of the metal ions to be mixed include solutions of aluminum compounds, such as alum and sulfuric acid band; and of trivalent metal ions, such as iron sulfate, iron chloride, sodium aluminate, borax, and boric acid; together with calcium chloride solutions. In addition to the above, an auxiliary agent for adjusting pH, such as aqueous sodium hydroxide, sulfuric acid aqueous solution, or the like, is mixed beforehand into metal ion solution. This is because the degree of viscosity increase varies with pH. For example, viscosity of guar gum increases when its pH is on the alkaline side, whereas that of CMC increases when its pH is on the acidic side. The mixing ratio of these metal ion solutions, in the form of a 0.5 to 10% aqueous solution, to unmixed foam-generating solution is preferably about 5 to 10% by volume. This is because of the problem that when the mixing ratio is below 5%, a marked viscosity increase by desired gelatinization is not achieved, whereas when the mixing ratio is over 10%, volumetric shrinkage, such as syneresis, occurs due to agglutination, preventing formation of firm foam. It should be noted that, when the soil to be excavated changes to zone III or zone II, the pump P may be stopped, so that the operation of gelatinization is stopped and thereby foam can be provided to the face at a constant viscosity and a constant foaming ratio. This can reduce pump load associated with viscosity increase and, with only switching being required, facilitate changes in accordance with soil properties without interrupting work. EXAMPLE 1 Using washed sand, three types of foam with different viscosities, type A, type B, and gel type B, were injected and slumps as well as injection ratio were compared as shown in the following tables 1 to 3. All the slumps were measured with a C type viscometer. (Table Removed) Each table reveals that the higher the viscosity of foam the larger the slump is, suggesting that as foam strength is increased by enhancing viscosity foam becomes resistant to collapse or disappear. EXAMPLE 2 A 0.6% solution of guar gum, which is a component of the viscosity-enhancing agent, was gelatinized using iron chloride, Viscosity changes with pH were examined using caustic soda solution as pH adjuster. Results shown in the following Table 4 were obtained. The viscosity of the solution state was measured with a viscosity tester. (Table Removed) This table confirms that viscosity is increased in the presence of ferric chloride ions and that, even though equal volumes were added, as the pH becomes more alkaline, the viscosity increases. EXAMPLE 3 A 0.6% solution of guar gum, which is a component of the viscosity-enhancing agent, was gelatinized using sodium aluminate. Viscosity changes with pH were examined using dilute sulfuric acid solution as a pH adjuster. Results shown in the following Table 5 were obtained. The viscosity of the solution state was measured with a viscosity tester. (Table Removed) This table reveals that there is no viscosity-enhancing effect when the pH is on the acidic side, and that excessive alkalinity has the opposite effect of decreasing viscosity; the optimal viscosity-enhancing effect is obtained at the proper pH level (pH 9.5) . It should be noted that since sodium aluminate itself is an alkaline substance its pH changes with the volume of dilute sulfuric acid added. EXAMPLE 4 A 0.6% solution of guar gum, which is a component of a viscosity-enhancing agent, was gelatinized using borax. Viscosity changes with pH were examined. Results shown in the following Table 6 were obtained. The viscosity of the solution state was measured with a viscosity tester. Table 6 (Table Removed) This table reveals that viscosity increases with increasing volume of the metal ions and that the optimal viscosity-enhancing effect is obtained at the proper pH level (pH 9.0). The present invention is suitable for excavation of a highly permeable gravel layer in the rheological foam shield tunneling method. According to the present invention, the main component of the foam discharged through the foam generator is gelatinized by adding metal ion solution, with the expected foaming ratio being maintained at the expect level, and released from the tip of the tunneling machine in the state of enhanced viscosity. Preferred examples of the metal ions to be used are trivalent metal ions or calcium ions. The pH is maintained such that viscosity can be easily enhanced by adding an auxiliary agent for pH adjustment. We Claim: 1. A method for generating foam in the rheological foam shield tunneling method, comprising the steps of: adding one selected from the group consisting of carboxymethylcellulose, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa.s with a foaming generator; adding and mixing an aqueous solution of metal ions in the form of a 0.5 to 10% aqueous solution into foam obtained immediately after the generation, with the mixing ratio of aqueous solutions of metal ions to unmixed foam generating solution is 5 to 10% by volume. 2. The method for generating foam in the rheological foam shield tunneling method as claimed in claim 1, wherein guar gum is added as the viscosity-enhancing agent. 3. The method for generating foam in the rheological foam shield tunneling method as claimed in claim 1 or 2, wherein the metal ions are trivalent metal ions or calcium ions. 4. The method for generating foam in the rheological foam shield tunneling method as claimed in any one of claims 1 to 3, wherein an auxiliary agent for pH adjustment has been added to the aqueous solution of the metal ions. 5. A foaming material prepared by the method for generating foam as claimed in any one of the preceding claims, wherein said material is used for the rheological foam shield tunneling method.

Full Text

TECHNICAL FIELD
The present invention relates to a method for generating foam and foaming materials suitable for use particularly in a highly permeable gravel layer in the rheological foam shield tunneling method.
BACKGROUND ART
Mud-making materials currently used in soil pressure
balanced shield are categorized as (a) bentonite-based, (b)
cellulose-based, (c) polyacrylamide-based, (d)
water-absorbing resin-based, and (e) surfactant-based
materials.
Among these, foaming agents used in the rheological foam shield tunneling method belong to (e) surfactant-based materials and are formed by mixing air into aqueous solution of a special foaming agent (OK-2: a preparation formulated using cellulose macromolecules made from pulp as the main agent of a foam-generating material) . By injecting this foaming material into the excavation face, it is possible to improve the fluidity and watertightness of excavated soil and also to prevent adhesion of excavated soil to the interior walls of the chamber. This enables smooth tunnel excavation while maintaining the face in a stable condition.
Further, in the rheological foam shield tunneling method,
the type of foaming material is determined based on the
properties of the soil be excavated, i.e., the grain size
distribution curve, (see technical information on the
rheological foam shield tunneling method: "Soil
Characteristics and Criteria for Selection of Special Foaming
materials," published by the Shield Tunneling Association of
Japan, March 2003 [refer to
http://www.shield-method.gr.jp/what/kiho.pdf]). For example, as shown in FIG. 1, the applicable range of type A (solution viscosity: 2.7 mPa.s) is zone I or zone II consisting of clay, silt, fine sand, etc., whereas the applicable range of type B (solution viscosity: 300 mPa.s) is zone II to III consisting of fine sand, coarse sand, etc.
Type B materials are applicable to zone II to III in that their foam strength has been enhanced by conferring viscosity on foam by adding the viscosity-enhancing agent OK-2 to OK-1.
However, in a highly permeable gravel layer, particularly in a type of soil with a large coefficient of permeability, belonging to zone IV, even when type B is used, foam is prone to disappear because of the gush of abundant ground water. This has presented problems such as the unstable condition of the face or soil eruption from the screw conveyor, causing trouble in tunnel driving.
Consequently, another additive or supplementary construction method is required to be used in combination . This is because increasing viscosity more than that of the conventional type B causes an increase in the pressure and blocking within the foaming generator that are associated with the increased viscosity. As a result, the foaming ratio is decreased to the extent that 6-fold foam generation, the standard of type B in the rheological foam shield tunneling method, cannot be achieved.
The present invention solves the above-mentioned problems. It provides a method for generating foam in the rheological foam shield tunneling method and a foaming material used for the rheological foam shield tunneling method, which enable implementation of the rheological foam shield tunneling method without using any other additive or supplementary construction method even in a highly permeable gravel layer by further increasing viscosity while maintaining the expected foaming ratio using a type B foam-generating material.
DISCLOSURE OF THE INVENTION
The method for generating foam according to the present

invention includes the steps of adding one selected from the group consisting of CMC, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa. s through a foaming generator at the predetermined foaming ratio; and adding and mixing an aqueous solution of metal ions into foam obtained immediately after the generation.
In the method of claim 1 according to the present invention, the metal ions are trivalent metal ions or calcium ions. Further, in the method of claim 1 or 2 according to the present invention, an auxiliary agent for pH adjustment has been added to the metal ions.
The foaming material used for the rheological foam shield tunneling method according to the present invention is obtained immediately after undergoing the steps of adding one selected from the group consisting of CMC, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent; and foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa.s through a foaming generator at the predetermined foaming ratio.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing soil characteristics and the criteria for selection of foam-generating materials.
FIG. 2 is illustrative sectional view of the rheological foam shield tunneling method to which the method according to the present invention is applied.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 shows the rheological foam shield tunneling method to which the method of the present invention is applied. Referring to the figure, 1 is a shield tunneling machine, and 2 is a tunnel segment constructed behind the tunneling machine 1.

The shield tunneling machine 1 includes a cutter disc 4 at the front of a cylindrical skin plate 3, and is configured to excavate the face by rotating the cutter disc 4 while moving forward by exerting reaction force on the front end part of the segment 2 with a jack (not shown in the figure) , to transport, with a screw conveyor 7, excavated muck taken into a chamber 6 defined by a partition wall 5 behind the cutter disk 4, and to transfer the muck to the muck car placed behind the conveyor so that the muck is removed.
Inside the tunnel enclosed by the segment 2, behind the tunneling machine 1, are laid conveyor rails 8. In the embodiments of the present invention, various back-up cars constituting the foam-generation plant are linked in a line on these rails 8. The back-up cars consist of, in the order from the last, a foam-generating material tank car 9, a driving car 10, a control car 11, and a foam generation car 12, together with a metal ion tank 13 placed above the foam generation car 12.
The tank car 9 provisionally retains the foam-generating material supplied by a foam-generating material pipeline 14' drawn into the tunnel. The driving car 10 is equipped with a foam-generating material injection pump 15 and an air compressor 16. The control car is mounted with a control system
17 for the pump 15 and the compressor 16. The foam generation
car 12 is equipped with a foaming generator 18. These cars are
linked through the foam-generating material supply line and air
line.
By driving the plant, the foam-generating material retained in the tank car 9 is transferred to the foam generator
18 by the pump 15. By mixing the pressure air produced by the
air compressor 16 within the foam generator 18 at the
predetermined pressure ratio, the foam-generating material is
discharged to the front of the cutter disc 4 through the foam
injection pipe 19.
Further, near the discharge end of the foam generator 18 in the foam injection pipe 19, which is connected to the metal

ion tank 13 through a supply pipe 20 and a pump P, metal ion solution is mixed into the foam generated within the foam generator 18. The mixing ratio is set to the predetermined ratio by controlling the drive of the pump P by the aforementioned control system 17.
In the above-mentioned plant, the foam-generating material to be used is a type B foam-generating material complying with the aforementioned zones II to III. This foam-generating material is a foam-generating solution that contains as the main components, in addition to the above-mentioned OK-1, which is the main component of the foam-generating material, one selected from the group consisting of CMC, guar gum, and alginic acid, or their mixture . The viscosity of the foam-generating solution is adjusted to 300 to 500 mPa.s.
CMC, guar gum, and alginic acid, or their mixture to be added is gelatinized in the presence of trivalent metal ions or calcium ions, whereby its viscosity is increased, e.g., 2 to 40-fold.
Thus, in the present invention, viscosity of foam is increased, while maintaining the foaming ratio at the expected ratio, by mixing metal ion solution into the foam, and this highly-viscous foam is provided at the front of the cutter disc 4. As a result, smooth excavation is possible without using any other additive or supplementary construction method even in a highly permeable gravel layer, i.e., a type of soil with a large coefficient of permeability belonging to zone IV. In addition, plastic fluidity and watertightness is improved, whereby soil eruption from the screw conveyer can be prevented.
Examples of the metal ions to be mixed include solutions of aluminum compounds, such as alum and sulfuric acid band; and of trivalent metal ions, such as iron sulfate, iron chloride, sodium aluminate, borax, and boric acid; together with calcium chloride solutions.
In addition to the above, an auxiliary agent for adjusting pH, such as aqueous sodium hydroxide, sulfuric acid aqueous

solution, or the like, is mixed beforehand into metal ion solution. This is because the degree of viscosity increase varies with pH. For example, viscosity of guar gum increases when its pH is on the alkaline side, whereas that of CMC increases when its pH is on the acidic side.
The mixing ratio of these metal ion solutions, in the form of a 0.5 to 10% aqueous solution, to unmixed foam-generating solution is preferably about 5 to 10% by volume. This is because of the problem that when the mixing ratio is below 5%, a marked viscosity increase by desired gelatinization is not achieved, whereas when the mixing ratio is over 10%, volumetric shrinkage, such as syneresis, occurs due to agglutination, preventing formation of firm foam.
It should be noted that, when the soil to be excavated changes to zone III or zone II, the pump P may be stopped, so that the operation of gelatinization is stopped and thereby foam can be provided to the face at a constant viscosity and a constant foaming ratio. This can reduce pump load associated with viscosity increase and, with only switching being required, facilitate changes in accordance with soil properties without interrupting work.
EXAMPLE 1
Using washed sand, three types of foam with different viscosities, type A, type B, and gel type B, were injected and slumps as well as injection ratio were compared as shown in the following tables 1 to 3. All the slumps were measured with a C type viscometer.
(Table Removed)

Each table reveals that the higher the viscosity of foam the larger the slump is, suggesting that as foam strength is increased by enhancing viscosity foam becomes resistant to collapse or disappear.
EXAMPLE 2
A 0.6% solution of guar gum, which is a component of the viscosity-enhancing agent, was gelatinized using iron chloride, Viscosity changes with pH were examined using caustic soda solution as pH adjuster. Results shown in the following Table 4 were obtained. The viscosity of the solution state was measured with a viscosity tester.
(Table Removed)

This table confirms that viscosity is increased in the presence of ferric chloride ions and that, even though equal volumes were added, as the pH becomes more alkaline, the viscosity increases.
EXAMPLE 3
A 0.6% solution of guar gum, which is a component of the viscosity-enhancing agent, was gelatinized using sodium aluminate. Viscosity changes with pH were examined using dilute sulfuric acid solution as a pH adjuster. Results shown in the following Table 5 were obtained. The viscosity of the solution state was measured with a viscosity tester.
(Table Removed)

This table reveals that there is no viscosity-enhancing effect when the pH is on the acidic side, and that excessive alkalinity has the opposite effect of decreasing viscosity; the optimal viscosity-enhancing effect is obtained at the proper pH level (pH 9.5) . It should be noted that since sodium aluminate itself is an alkaline substance its pH changes with the volume of dilute sulfuric acid added.
EXAMPLE 4
A 0.6% solution of guar gum, which is a component of a viscosity-enhancing agent, was gelatinized using borax. Viscosity changes with pH were examined. Results shown in the following Table 6 were obtained. The viscosity of the solution state was measured with a viscosity tester.
Table 6
(Table Removed)

This table reveals that viscosity increases with increasing volume of the metal ions and that the optimal viscosity-enhancing effect is obtained at the proper pH level (pH 9.0).
The present invention is suitable for excavation of a highly permeable gravel layer in the rheological foam shield tunneling method.
According to the present invention, the main component of the foam discharged through the foam generator is gelatinized by adding metal ion solution, with the expected foaming ratio being maintained at the expect level, and released from the tip of the tunneling machine in the state of enhanced viscosity. Preferred examples of the metal ions to be used are trivalent metal ions or calcium ions. The pH is maintained such that viscosity can be easily enhanced by adding an auxiliary agent for pH adjustment.

We Claim:
1. A method for generating foam in the rheological foam shield tunneling method,
comprising the steps of:
adding one selected from the group consisting of carboxymethylcellulose, guar gum, and alginic acid, or their mixture, as a viscosity-enhancing agent, to a foam-generating material as the main agent;
foaming a foam-generating solution whose viscosity is adjusted to 300 to 500 mPa.s with a foaming generator;
adding and mixing an aqueous solution of metal ions in the form of a 0.5 to 10% aqueous solution into foam obtained immediately after the generation, with the mixing ratio of aqueous solutions of metal ions to unmixed foam generating solution is 5 to 10% by volume.
2. The method for generating foam in the rheological foam shield tunneling method as claimed in claim 1, wherein guar gum is added as the viscosity-enhancing agent.
3. The method for generating foam in the rheological foam shield tunneling method as claimed in claim 1 or 2, wherein the metal ions are trivalent metal ions or calcium ions.
4. The method for generating foam in the rheological foam shield tunneling method as claimed in any one of claims 1 to 3, wherein an auxiliary agent for pH adjustment has been added to the aqueous solution of the metal ions.
5. A foaming material prepared by the method for generating foam as claimed in any one of the preceding claims, wherein said material is used for the rheological foam shield tunneling method.

Documents:

574-DELNP-2006-Abstract-(27-08-2010).pdf

574-delnp-2006-abstract.pdf

574-DELNP-2006-Claims-(20-09-2011).pdf

574-DELNP-2006-Claims-(27-08-2010).pdf

574-delnp-2006-claims.pdf

574-DELNP-2006-Correspondence Others-(20-09-2011).pdf

574-DELNP-2006-Correspondence-Others-(25-11-2010).pdf

574-DELNP-2006-Correspondence-Others-(27-08-2010).pdf

574-delnp-2006-correspondence-others.pdf

574-delnp-2006-correspondence-others1.pdf

574-DELNP-2006-Description (Complete)-(27-08-2010).pdf

574-delnp-2006-description (complete).pdf

574-DELNP-2006-Drawings-(27-08-2010).pdf

574-delnp-2006-drawings.pdf

574-DELNP-2006-Form-1-(27-08-2010).pdf

574-delnp-2006-form-1.pdf

574-delnp-2006-form-18.pdf

574-DELNP-2006-Form-2-(27-08-2010).pdf

574-delnp-2006-form-2.pdf

574-delnp-2006-form-3.pdf

574-delnp-2006-form-5.pdf

574-DELNP-2006-GPA-(27-08-2010).pdf

574-delnp-2006-gpa.pdf

574-delnp-2006-pct-210.pdf

574-delnp-2006-pct-301.pdf

574-delnp-2006-pct-304.pdf

574-delnp-2006-pct-306.pdf

574-delnp-2006-pct-307.pdf

574-delnp-2006-pct-308.pdf

574-delnp-2006-pct-311.pdf

574-delnp-2006-pct-332.pdf

574-delnp-2006-pct-346.pdf

574-DELNP-2006-Petition 137-(27-08-2010).pdf

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Patent Number

250275

Indian Patent Application Number

574/DELNP/2006

PG Journal Number

51/2011

Publication Date

23-Dec-2011

Grant Date

21-Dec-2011

Date of Filing

03-Feb-2006

Name of Patentee

OBAYASHI CORPORATION

Applicant Address

4-33, KITAHAMA-HIGASHI, CYUO-KU,OSAKA-SHI, OSAKA 540-0031, JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	KEIZO MIKL,	C/O OBAYASHI CORPORATION, TOKYO HEAD OFFICE,15-2, KONAN 2-CHOME,MINATO-KU,TOKYO 108-0075, JAPAN.
2	YOICHI MORIYA	C/O OBAYASHI CORPORATION, TOKYO HEAD OFFICE,15-2, KONAN 2-CHOME,MINATO-KU,TOKYO 108-0075, JAPAN.
3	MASAYOSHI IZAWA,	C/O OBAYASHI CORPORATION, TOKYO HEAD OFFICE,15-2, KONAN 2-CHOME,MINATO-KU,TOKYO 108-0075, JAPAN.

PCT International Classification Number

C07D

PCT International Application Number

PCT/JP2004/012883

PCT International Filing date

2004-08-30

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2003-307983	2003-08-29	Japan