JP2018193689A - Bubbles-containing anti-friction materials, bubbles-containing fluidizing materials, producing method thereof and construction method of shield by using them - Google Patents

Abstract

To provide bubbles-containing anti-friction materials, bubbles-containing fluidizing materials, a method for producing them and a shielding method, which can maintain volume variability of bubbles for a long time, have resistance to dilution with water and can reduce the used amount of plastic clay to be substantial anti-friction materials (fluidizing materials).SOLUTION: Bubbles-containing anti-friction materials (bubbles-containing fluidizing materials) contain clay sand, water, bubbles and a plasticity strength conditioner. The bubbles-containing anti-friction materials (bubbles-containing fluidizing materials) are produced by mixing the liquid A fed from a liquid A tank 14 and the bubbles discharged from a foaming gun 6 in a line mixer part 10, then adding the liquid B fed from a liquid B tank 16. The bubbles-containing anti-friction materials (bubbles-containing fluidizing materials) are discharged from an anti-friction materials injection nozzle 23 (fluidizing materials injection nozzle) after being fed from an anti-friction materials discharge port 24 (fluidizing material discharge port 26) through an anti-friction materials line 25 (fluidizing materials line 27) and also fill between the natural ground drilled by a shield machine 1 and an outer peripheral surface of a machine body 2, or between a working face and a cutter head 3, or between the cutter head 3 and the natural ground.SELECTED DRAWING: Figure 1

Description

  The present invention is a foamed anti-friction material that is filled between the shield machine and the ground to be excavated to reduce friction between the two, and added to the earth and sand excavated when the shield machine is excavated. The present invention relates to a bubbled fluidizing material to be applied, a manufacturing method thereof, and a shield method.

  Conventionally, in the shield method using a shield machine, an outer peripheral bit is attached to the outer circumference of the cutter head facing the face that is the cutting section in order to reduce the frictional resistance generated between the shield machine and the surrounding ground. It is installed so that a slight gap is formed between the outer peripheral surface of the body of the shield machine and the surrounding ground. However, if residual soil from the cut soil or earth and sand generated by the collapse of surrounding ground enters the gap, its anti-friction effect may be reduced. Has been attempted (for example, see Patent Documents 1 to 3).

  Also, in the shield method using a shield machine, the excavated soil is filled in the chamber of the shield machine, and this earth pressure counters the face pressure and groundwater pressure to prevent the face from collapsing. In addition, in order to impart appropriate fluidity to the excavated soil, a fluidizing material is added to the front of the excavator or to the chamber (see, for example, Patent Document 4).

JP-A-5-202893 Japanese Patent Publication No.7-74589 Japanese Patent No. 5533267 JP 2006-182962 A

  As the antifriction material, for example, polymers, bentonite, bubbles, plastic clay, and the like have been used.

  In addition, as the fluidizing material, for example, polymers, bentonite, bubbles, plastic clay, and the like have been used.

  One-component materials such as polymer and bentonite are easily diluted with groundwater and the like and have a limited anti-friction effect.

  Bubbles have the feature of variable volume of compression / expansion by pressure, and although the effect of reducing friction and improving fluidity is high, the retention of bubbles is low and they tend to disappear over time, and the antifriction and fluidization effects are limited. It was the target.

  On the other hand, plastic clay is composed of a suspension containing a large amount of mineral materials such as clay and bentonite as the main material, and a polymer material and water glass are used as the secondary material, and the two liquids are proportionally mixed immediately before injection. By doing so, the resistance to water dilution was increased by changing the plastic clay properties.

  Plastic clay has an anti-friction effect and a fluidizing effect, but there is a need for a material that is more stable and can maintain the anti-friction and fluidizing effects for a long time. Moreover, since plastic clay is very expensive compared with other materials, cost reduction is also a big subject.

  The present invention has been made in view of the above-described problems and the like, and can maintain the volume variability of bubbles for a long time and is resistant to water dilution, and is a plastic clay that is a substantial antifriction material. A first object is to provide a foamed antifriction material capable of reducing the amount of use, a method for producing the same, and a shield method. Further, a foamed fluidizing material that can retain the volume variability of bubbles for a long time, is resistant to water dilution, and can reduce the amount of plastic clay used as a substantial fluidizing material, and a method for producing the same A second object is to provide a shield method.

In order to achieve the first object, the antifriction material containing bubbles according to the first invention is:
In the antifriction material with air bubbles that is filled between the shield machine and the ground to be excavated to reduce friction between the two,
(A) clay sand which is a clay-like aggregate of clay minerals,
(B) water,
(C) It is characterized by containing bubbles generated by blowing a gas into a foaming solution containing a foaming agent, and (d) a plastic strength modifier that increases the plastic strength.

In order to achieve the second object, the fluidized material with bubbles according to the second invention is:
(A) clay sand, which is a soil-like aggregate of clay minerals, in the fluidizing material added to the excavated soil in front of the shield machine or in the chamber;
(B) water,
(C) It is characterized by containing bubbles generated by blowing a gas into a foaming solution containing a foaming agent, and (d) a plastic strength modifier that increases the plastic strength.

Next, the manufacturing method of the foamed antifriction material according to the third invention is:
A method for producing a foamed antifriction material that is filled between a shield machine and a natural ground to be excavated to reduce friction between the two,
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent It is characterized by adding an agent.

Moreover, the manufacturing method of the bubbled fluidizing material according to the fourth invention is:
A method for producing a bubbled fluidizing material added to excavated soil in front of or in a chamber of a shield machine
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent It is characterized by adding an agent.

Next, the shield method according to the fifth invention is a shield method using a shield machine,
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent The anti-friction material containing bubbles obtained by adding the agent is filled between the shield machine and the natural ground to be excavated.

  In the shield method according to the fifth aspect of the present invention, the blowing of the gas blown into the foaming solution according to the pressure acting on the peripheral surface of the shield machine based on the amount of gas blown into the foaming solution under atmospheric pressure. It is preferable to adjust the amount of intrusion (sixth invention).

Furthermore, the shield method according to the seventh invention is:
In the shield method using a shield machine,
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent The aerated fluidizing material obtained by adding the agent is added to the excavated soil in front of the shield machine or in the chamber.

  In the shielding method of the seventh invention, the blowing of the gas blown into the foaming solution according to the pressure acting on the front surface of the shield machine based on the blowing amount of the gas blown into the foaming solution under atmospheric pressure The amount is preferably adjusted (eighth invention).

  According to the foamed antifriction material of the first invention and the foamed fluidizing material of the second invention, bubbles having a variable volume are included in the plastic clay-like material that is resistant to water dilution, and are plasticized by the plastic strength adjusting agent. Since the strength is increased, the volume variability of the bubbles can be maintained for a long time and it is resistant to water dilution. Moreover, the inclusion of bubbles causes the mass of the antifriction material and the fluidizing material to include the bubbles. Since the amount is relatively reduced as compared with the case where there is no material, the amount of plastic clay used as a substantial antifriction material and fluidizing material can be reduced.

  According to the method for producing a foamed antifriction material of the third invention and the method for producing a foamed fluidizing material of the fourth invention, the clay sand aqueous solution and the bubbles are first mixed to disperse the bubbles in the clay sand aqueous solution. After that, since the plastic strength of the aerated clay sand aqueous solution is increased by the addition of the plastic strength modifier, it is possible to obtain a bubbling antifriction material and a bubbling fluidized material in which the bubbling is uniformly mixed.

According to the shield construction method of the fifth invention, since the antifriction material containing bubbles strong against water dilution that keeps the volume variability of the bubbles long is filled between the shield machine and the natural ground to be excavated, Air bubbles holding internal pressure can suppress the loosening of the natural ground until the shield machine passes, and the cushioning property of the air bubbles can reduce vibrations during natural ground excavation and alleviate the impact on the ground surface. It is possible to stably excavate natural ground with a shield machine.
Further, according to the shield construction method of the seventh invention, since the fluidizing material with bubbles, which is strong against water dilution and has long volume variability with bubbles, is added to the excavated soil in front of the shield machine or in the chamber, The shield excavator can be digged while preventing the fall of the face by preventing the face from collapsing with the face pressure and groundwater pressure, etc., by the bubbles holding the internal pressure, and appropriate fluidity can be imparted to the excavated soil.

  By adopting the configurations of the sixth invention and the eighth invention, it is possible to reliably ensure the internal pressure of the bubbles necessary to suppress the looseness of the natural ground.

It is a longitudinal cross-section of the shield machine used for implementation of the shield construction method using the foamed antifriction material and the foamed fluidizing material of the present invention.

  Next, specific embodiments of the foamed antifriction material, the foamed fluidizing material, the production method thereof, and the shield method according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a longitudinal section of a shield machine used for carrying out a shield method using the bubble-containing antifriction material and the bubble-containing fluidizing material of the present invention.

<Description of shield machine>
A shield machine 1 shown in FIG. 1 includes a cylindrical body 2 and a cutter head 3 that is rotatably supported on the front portion of the body 2, and is provided by a rotary drive device (not shown) built in the body 2. The cutter head 3 is driven to rotate, and the cutter head 3 can perform face excavation. This shield machine 1 is equipped with a bubble-containing antifriction material / fluidizing material injection device 4. The foamed antifriction material / fluidizing material injection device 4 injects the foamed antifriction material generated by generating the foamed antifriction material into the gap between the outer peripheral surface of the body 2 and the surrounding natural ground, The bubbled fluidizing material is generated and added to the excavated soil in front of the cutter head 3 or in the chamber 7.

<Description of foaming antifriction material / fluidizing material injection device>
The foamed antifriction material / fluidizing material injection device 4 includes a mixing device 5 disposed inside the body 2 and a foaming gun (foaming device) 6 disposed behind the mixing device 5. Yes.

  The mixing device 5 includes a line mixer unit 10 that is a static mixer, a first merging unit 11 provided on the upstream side of the line mixer unit 10, and a second merging unit 12 provided on the downstream side of the line mixer unit 10. A liquid tank 14 is connected to the first merging portion 11 via the A liquid line 13, and a B liquid tank 16 is connected to the second merging portion 12 via the B liquid line 15. Yes. A liquid feed pump, a pressure switch, a pressure sensor, a flow meter and the like (not shown) are appropriately provided in the middle of each of the A liquid line 13 and the B liquid line 15.

  A foaming solution tank 18 is connected to the upstream end portion of the foaming gun 6 through a foaming solution line 17, and an air compressor 20 is connected through an air line 19. Further, the downstream end portion of the foaming gun 6 and the first joining portion 11 in the mixing device 5 are connected by a bubble line 21. A liquid feed pump, a pressure switch, a pressure sensor, a flow meter and the like (not shown) are appropriately provided in the middle of the foaming solution line 17, and a filter regulator, pressure sensor, and air (not shown) are provided in the middle of the air line 19. A flow meter, an air control valve, and the like are provided as appropriate.

  An injection port 22 is formed in the outer peripheral wall of the body 2 so as to face the excavated ground, and an anti-friction material injection nozzle 23 is attached to the injection port 22. An antifriction material discharge port 24 is provided on the downstream side of the second junction 12 in the mixing device 5. The antifriction material injection nozzle 23 and the antifriction material discharge port portion 24 are connected by an antifriction material line 25.

  The cutter head 3 or the chamber 7 is equipped with a fluidizing material injection nozzle (not shown) so that the fluidizing material can be added to the excavated soil excavated by the shield machine 1. A fluidizing material discharge port portion 26 is provided on the downstream side of the second joining portion 12 in the mixing device 5. A fluidizing material injection nozzle (not shown) provided in the cutter head 3 or the chamber 7 and the fluidizing material discharge port 26 are connected by a fluidizing material line 27.

<Description of manufacturing method of foamed antifriction material and foamed fluidized material>
Next, the production method of the foamed antifriction material and the fluidized foamed material of the present invention will be described. Since both production methods are basically the same, the production of the foamed antifriction material of the present invention is representative. The method will be mainly described below.

  The foamed antifriction material of the present invention is suitable for an aqueous clay sand solution (hereinafter referred to as “liquid A”, for example, having a viscosity of 1 to 10 dPa · s) containing a mineral clay sand which is an earth-like aggregate of clay minerals. A special water glass (hereinafter referred to as “liquid B”, for example, a viscosity of 1 to 2 dPa · s) as a plastic strength adjusting agent for increasing the plastic strength is mixed and mixed in a proportional amount. The By adding the B liquid, the foamed antifriction material immediately becomes a highly viscous clay (for example, 300 to 1200 dPa · s). Here, as the clay sand, for example, TAC-β manufactured by Tac Co., Ltd. is suitable, and the inorganic crystal is a pollution-free material mainly composed of sericite (sericite clay) and montmorillonite, and the mineral crystals are fine and viscous. Because of its richness, it is used as a premix for clay and bentonite in a wide range of applications as a material for injecting mineral additives and muddy water. Moreover, as the special water glass, for example, TAC-3G manufactured by Tac Co., Ltd. is suitable.

  In the above manufacturing method, after the liquid A and the bubbles are first mixed and the bubbles are dispersed in the liquid A, the plastic strength of the liquid A containing the bubbles is increased by the addition of the liquid B. A foamed antifriction material (a foamed fluidizing material) can be obtained.

  According to the foamed high-viscosity plastic antifriction material (the foamed high-viscosity plastic fluidizing material) thus obtained, bubbles having a variable volume are included in the plastic clay-like material that is resistant to water dilution. In addition, since the plastic strength is enhanced by the plastic strength modifier, the volume variability of the bubbles can be maintained for a long time and it is resistant to water dilution. Since the mass relative to the bulk of the material is relatively reduced as compared with the case where no bubbles are included, a substantial amount of the antifriction material (fluidizing material) used can be reduced.

  The bubbles are produced by stirring the foaming solution (foaming agent stock solution + diluted water) supplied from the foaming solution tank 18 and the air supplied from the air compressor 20 with the foaming gun 6. Depending on the concentration of the foaming solution and the expansion ratio, the properties of the bubbles are different.

  As the foaming agent, since it is assumed to be used in a shield mine, a surfactant is better than a protein-based foaming agent that emits a specific odor. Examples of the surfactant include α-olefin sulfonate (AOS) and alkyl ether sulfate (AES). From the viewpoint of forming long-lived stable bubbles, it is desirable to contain dodecanol or tetradecanol. Furthermore, it is desirable to contain 2-ethylhexyl glyceryl ether from a viewpoint of improving foamability more.

  The concentration of the foaming solution is a ratio of the foaming agent stock solution to the foaming solution, but generally 1 to 3% is preferable. The 1% concentration means that the stock solution is 0.01 volume and the diluted water is 0.99 volume in 1 volume of the aqueous solution.

  The expansion ratio is a ratio of the air volume to the foaming solution volume, but preferably 10 to 20 times. In addition, when using it as a drilling additive for the bubble shield method, it is changed depending on the ground. In sandy soil, hard air bubbles (a lot of air and foaming ratio of about 20 times (foaming solution: air = 1: 19)) are often used. In clay soil, soft air bubbles are used. (Many foaming solutions and foaming ratio of about 10 times (foaming solution: air = 1: 9)) are often used.

<Description of shield method>
Next, the shield construction method using the shield machine 1 of the present invention will be described below with reference to FIG.

  In FIG. 1, the foaming solution (foaming agent stock solution + diluted water) stored in the foaming solution tank 18 is fed to the foaming gun 6 through the foaming solution line 17 and from the air compressor 20. Is supplied to the foaming gun 6 through the air line 19, and the foaming solution and air are mixed and stirred by the foaming gun 6 to generate a shaving cream-like bubble.

  A liquid A (clay sand aqueous solution) stored in the liquid A tank 14 is fed into the first junction 11 in the mixing device 5 through the liquid A line 13, and bubbles generated in the foaming gun 6 are bubbled. It is fed through the line 21, and the liquid A and the bubbles are merged at the first merge unit 11. The merged liquid A and bubbles are sent to the line mixer unit 10 where the liquid A and the bubbles are stirred and mixed.

  The second merging section 12 in the mixing device 5 is fed with the mixed solution of the liquid A and the air bubbles mixed in the line mixer section 10, and the liquid B (special water glass) stored in the liquid B tank 16. ) Is fed through the B liquid line 15, and the B liquid is added to the mixed solution of the A liquid and the bubbles in the second junction 12. As a result, a foamed antifriction material is generated, and the generated antifriction material is supplied from the antifriction material discharge port 24 to the antifriction material injection nozzle 23 via the antifriction material line 25. . The bubble-containing antifriction material fed to the antifriction material injection nozzle 23 is discharged from the antifriction material injection nozzle 23 toward the gap between the outer peripheral surface of the body 2 of the shield machine 1 and the surrounding natural ground. The air-filled antifriction material is injected and filled into the gap.

  In the shield construction method using the shield machine 1, the antifriction material containing bubbles is filled between the natural ground excavated by the shield machine 1 and the outer peripheral surface of the trunk 2 in accordance with the excavation of the shield machine 1. As a result, disturbance due to friction between the shield machine 1 and the surrounding natural ground can be reduced, and reduction of thrust required for excavation (hereinafter referred to as “drilling thrust”) is realized. be able to. The reduction of thrust during excavation provides a margin for the shield load, enabling high-speed construction to improve productivity.

  Bubbles in the antifriction material line 25 are pressurized by the air compressor 20 and the injection pump to a pressure equal to or higher than the soil water pressure on the outer periphery of the shield, and volume contracts. As soon as the antifriction material passes through the inlet 22, the pressure is reduced and the bubbles expand to prevent the antifriction material itself from shrinking in volume. At the same time, it is possible to reduce the stress release on the outer periphery of the shield machine 1 by the pressure holding effect, and to suppress the loosening of the ground caused by excavation until the shield machine 1 passes.

  The influence on the ground surface such as vibration accompanying the excavation by the shield machine 1 can also be reduced by cushioning by the cushioning property of the independent bubbles contained in the antifriction material containing bubbles. In addition, 20-50% of a foamed antifriction material is suitable for the volume percentage of the closed cell to contain.

  The time required to hold the bubbles is from injection of the antifriction material containing bubbles until the body 2 of the shield machine 1 passes. The length of the body 2 of the shield machine 1 is usually about 5 m (small cross section) to a maximum of about 15 m (large cross section). Since the shield machine 1 is normally excavated day and night, it generally passes for one day, two days at most. Since the closed cells contained in the antifriction material containing bubbles are protected by a plastic viscous film, the defoaming time is dramatically increased, and the bubbles are held while the shield machine 1 passes. And can function effectively as a thrust reducing material.

  Similarly, a mixed solution of A liquid and bubbles after being mixed by the line mixer unit 10 is sent to the second merging unit 12 in the mixing device 5, and the B liquid stored in the B liquid tank 16 ( Special water glass) is fed through the B liquid line 15, and the B liquid is added to the mixed solution of the A liquid and the bubbles in the second junction 12. Thereby, the bubbled fluidizing material is generated, and the generated bubbled fluidizing material is fed from the fluidizing material discharge port portion 26 to the fluidizing material injection nozzle (not shown) via the fluidizing material line 27. The The bubbled fluidizing material fed to the injection nozzle is discharged from the fluidizing material injection nozzle in front of the cutter head 3 or in the chamber 7 and added to the excavated soil of the shield machine 1.

  In the shield method using the fluidizing material, the fluidizing material containing bubbles is added to the excavated soil of the shield machine 1 in front of the cutter head 3 of the shield machine 1 or in the chamber 7. Thereby, while being able to provide moderate fluidity to excavated soil, the torque at the time of rotation of the cutter head 3 can be reduced.

  As described above, the foamed antifriction material, the foamed fluidizing material, the production method thereof, and the shielding method of the present invention have been described based on one embodiment. However, the present invention is limited to the configuration described in the above embodiment. However, the configuration can be changed as appropriate without departing from the scope of the invention.

  For example, also in the propulsion method, it is applied as a bubble-containing antifriction material injected between the ground excavated after the propulsion pipe and the propulsion pipe, and a bubbled fluidizing material injected in front of the propulsion unit and in the chamber. There are also example embodiments. Moreover, you may apply not only to a tunnel but to the antifriction material and fluidization material in other construction.

  Next, specific examples of the foamed antifriction material, the foamed fluidizing material, the production method thereof, and the shield method of the present invention will be described.

  In order to confirm the sustainability of the bubbles alone, four types of foaming agents for the bubble shield method were obtained to produce bubbles (foaming solution concentration 1%, foaming ratio 10 to 20 times). Foaming agent No. 1 and no. 2 is a commercially available AOS system, and the foaming agent No. 3 and no. 4 is a commercially available AES system. Also, foaming agent No. 4 contains alkyltetradecanol and 2-ethylhexyl glyceryl ether in a specific weight ratio.

  Bubbles are introduced into a 1 L graduated cylinder, the amount of precipitation of the aqueous solution stored at the bottom is measured at each elapsed time, and the defoaming rate is calculated. When the expansion ratio is 10 times, the maximum amount of precipitation is 100 mg (= 100 mL). If the amount of precipitation after the elapsed time is 40 ml, the defoaming rate is 40 mL / 100 mL × 100 = 40%. The sustain rate is 100-40 = 60%. The test results are shown in Table 1 and Table 2 below.

  In the case of bubbles alone, the bubbles are almost eliminated or maintained slightly in one hour after injection. The difference in sustainability depending on the expansion ratio resulted in a high 20-fold expansion rate. For the type of foaming agent, no. 1-No. No. 3 The sustain rate of 4 was the best.

  Next, the bubble retention of the antifriction material mixed with the bubbles was confirmed. The selected antifriction materials were the following three types. One is a high viscosity additive (hereinafter referred to as “through shock”) obtained by mixing two liquids of a mineral clay bentonite solution (for example, TAC-α solution manufactured by Tac Co., Ltd.) and a polymer flocculant (for example, TAC through solution manufactured by Tac Co., Ltd.). "). The second is a plastic polymer filler (hereinafter simply referred to as “polymer filler”), which has a proven track record as a lubricant for long-distance propulsion work. The third is a foamed antifriction material (hereinafter referred to as “clay shock”) of the present invention. The bubbles to be mixed were the No. 1 that had the highest persistence. 4 was used.

  50% of bubbles were mixed with the above three kinds of antifriction materials (antifriction material: bubbles = 1: 1). The air volume was converted by measuring the density over time, and the sustainability was evaluated. The results are shown in Table 3 below.

  (1) The through shock was integrated with air bubbles immediately after mixing, but was defoamed and separated after 3 hours. (2) The polymer filler could not embrace bubbles. (3) The clay shock was good because it was integrated with bubbles and no separation over time was observed.

  The viscosity of each case during bubble mixing was measured. For the measurement of viscosity, No. 1 rotor of VT-04F manufactured by Rion Co., Ltd. was used. The measurement results are shown in Table 4 below. In addition, the standard of viscosity is about 0.01 dPa · s for fresh water, 5 dPa · s for bubbles, 60 dPa · s for jam, and about 300 dPa · s for tube grease. The viscosity of the bubble itself is also shown. As shown in Table 4 below, it can be clearly seen that bubbles are embraced even after only two days of clay shock.

  Next, the antifriction material was squeezed into a clay shock, and the sustainability was evaluated by changing the foaming ratio of the bubbles. The evaluation results are shown in Table 5 below. The volume ratio of clay shock to bubbles is 1: 1.

  Unlike the result of the bubbles alone, the sustainability at a foaming ratio of 10 times was high and the stability was excellent. It is considered that the one with a smaller expansion ratio (softer) is easier to be integrated with the antifriction material.

  In addition, the viscosity was also measured. The measurement results are shown in Table 6 below. As shown in Table 6, it can be seen that 10-fold foaming has less increase in viscosity and is more integrated with bubbles.

  Table 7 below shows the difference in sustainability due to the difference in bubble mixing ratio. Here, in addition to 50% (volume ratio 1: 1), the mixing ratio of bubbles to the antifriction material was 33% (volume ratio 2: 1) and 25% (volume ratio 3: 1). In order to confirm the difference in the types of foaming agents, 4 and the above No. 4. 3 was used.

  As apparent from Table 7 above, the smaller the bubble mixing rate, the higher the sustaining rate. In addition, foaming agent No. No. 4 is foaming agent No. 4. Compared to 3, the sustain rate is high.

  Next, test construction was carried out in actual shield construction (shield digging machine outer diameter φ12.47 m). The foaming agent used is No. 1 which has the highest sustainability of bubbles alone. No. 4 was selected, and the foaming solution concentration was 1% and the foaming ratio was 10 times.

  The bubble mixing ratio was 0% (clay shock only), 50%, 33%, and 25% of cases, and the shield shield machine continued for 1 captain (15m). The injection amount was 100% of the amount of extra excavation around the shield machine. The excavated soil was collected at the time of the test construction and brought back to carry out the particle size test at a later date. The grain composition was 21% gravel, 51% sand, 28% clay silt, and a sandy ground.

  In actual construction, the earth and water pressure is applied to the outer periphery of the shield machine, so an amount of air corresponding to the pressure is supplied to ensure a predetermined composition. The amount of air is in accordance with Boyle's law (PV = P'V '). For example, when the outer soil pressure is 0.1 MPa, it is twice under atmospheric pressure, and when 0.3 MPa, it is four times under atmospheric pressure. In the case of 0.4 MPa, an air amount that is five times the atmospheric pressure is supplied. As the soil water pressure at the injection site, the measured value of the earth pressure gauge installed on the side of the shield machine 1 is used, but the measured value of the in-chamber pressure gauge and the injection pressure of the antifriction material may be used.

  Table 8 below shows the average measured values of the bubble mixing ratio and the thrust at the time of excavation by the shield machine 1. In all cases, the excavation speed of the shield machine 1 was fixed at 35 to 40 mm / min. In addition, in the ground at the time of test construction, it is known that the thrust during excavation reaches 90% or more of the equipment thrust unless an antifriction material is injected into the outer periphery side of the body 2 of the shield machine 1.

  As is clear from the results shown in Table 8, the thrust at the time of excavation could be maintained at a low level at the bubble mixing ratio of 50% and 33% with respect to the bubble mixing ratio of 0%. It was confirmed that the cost could be reduced by mixing bubbles. In addition, when the bubble mixing ratio was 25%, the thrust during excavation was significantly reduced. When the injection was continued as it was, the fuselage itself of the shield machine 1 began to roll in the direction opposite to the forward rotation direction of the cutter head 3 during excavation. For this reason, the excavation was temporarily stopped and the cutter head 3 was reversely rotated to correct the rolling. As a result, the injection amount itself could be greatly reduced.

  As described above, when the antifriction material containing air bubbles is injected between the body 2 of the shield machine 1 and the excavated ground, the thrust during excavation is reduced due to the friction reducing effect, and high-speed construction can be realized to improve productivity. confirmed.

  The foamed antifriction material and the foamed fluidizing material of the present invention can retain the volume variability of the bubbles for a long time, are resistant to water dilution, and are a plastic that is a substantial antifriction material (fluidizing material). Since it has the characteristic that the amount of clay used can be reduced, it can be used suitably for applications such as reducing friction when drilling shield shield machines and reducing excavation resistance. Sex is great.

DESCRIPTION OF SYMBOLS 1 Shield machine 2 Body 3 Cutter head 4 Foamed antifriction material / fluidizing material injection device 5 Mixing device 6 Foaming gun 10 Line mixer section 11 First merge section 12 Second merge section 13 A liquid line 14 A liquid tank 15 B liquid line 16 B liquid tank 17 Foaming solution line 18 Foaming solution tank 19 Air line 20 Air compressor 21 Bubble line 22 Inlet 23 Antifriction material injection nozzle 24 Antifriction material discharge port 25 Antifriction material line

Claims (8)

In the antifriction material with air bubbles that is filled between the shield machine and the ground to be excavated to reduce friction between the two,
(A) clay sand which is a clay-like aggregate of clay minerals,
(B) water,
(C) A foamed antifriction material comprising bubbles generated by blowing a gas into a foaming solution containing a foaming agent, and (d) a plastic strength modifier that increases plastic strength. (A) clay sand, which is a soil-like aggregate of clay minerals, in the fluidizing material added to the excavated soil in front of the shield machine or in the chamber;
(B) water,
(C) A bubble-containing fluidizing material comprising bubbles generated by blowing a gas into a foaming solution containing a foaming agent, and (d) a plastic strength modifier that increases the plastic strength. A method for producing a foamed antifriction material that is filled between a shield machine and a natural ground to be excavated to reduce friction between the two,
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent A method for producing a foamed antifriction material, comprising adding an agent. A method for producing a bubbled fluidizing material added to excavated soil in front of or in a chamber of a shield machine
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent A method for producing a fluidized material with bubbles, comprising adding an agent. In the shield method using a shield machine,
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent A shield construction method characterized by filling an antifriction material containing bubbles obtained by adding an agent between a shield machine and a natural ground to be excavated.   6. The amount of gas blown into the foaming solution is adjusted according to the pressure acting on the peripheral surface of the shield machine based on the amount of gas blown into the foaming solution under atmospheric pressure. Shield construction method described in 1. In the shield method using a shield machine,
Plastic strength adjustment to increase the plastic strength after mixing the clay sand aqueous solution containing clay sand, which is a clay mineral earth-like aggregate, and the bubbles generated by blowing gas into the foaming solution containing foaming agent A shielding method characterized by adding a fluidized material containing bubbles obtained by adding an agent to excavated soil in front of a shield machine or in a chamber. The amount of gas blown into the foaming solution is adjusted according to the pressure acting on the front surface of the shield machine based on the amount of gas blown into the foaming solution under atmospheric pressure. The shield method described.

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