JPH10169365A - Method of shield tunneling method for weak soil and drilling-fluid additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excavate a weak soil stratum without resulting in the settlement of a soil stratum by injecting a drilling fluid containing a surface-active agent into a cutter chamber when the weak soil stratum having a specific N value is excavated by a method of shield tunneling. SOLUTION: When a weak solid stratum having an N value of 0-20 is excavated without generating conversion by a method of shield tunneling, a drilling fluid containing a surface-active agent is injected into a cutter chamber 2. The surface-active agent mainly comprises a nonionic surface-active agent having HLB of 6-10, the loading of the surface-active agent is et in 20g/m<3> or more to the drilling fluid, and the air surface tension of the drilling fluid is set in 35dyne/cm or less. When there is the nonionic surface-active agent having HLB of 6-10 in the drilling fluid and surface tension is lowered, the drilling fluid is permeated excellently to the front ground of a cutter 15 and deflocculated, only the ground of the front of the cutter 15 is excavated, back-filling can be conducted sufficiently without generating disturbance in the outer circumferential ground of the chamber 2, and no ground subsidence is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield method for soft soil suitable for excavating a soft soil layer having an N value of 0 to 20 by a shield method without causing ground displacement, and a cutter chamber in the shield method. The present invention relates to a drilling fluid additive that adjusts a drilling fluid such as muddy water and mud that is injected into the inside and contributes to promoting drilling.

[0002]

2. Description of the Related Art If a soft soil layer is excavated by a conventional mud pressure shield method using sludge mainly composed of bentonite, there is a problem that the soil is displaced after the completion of the tunnel, that is, the soil layer above the tunnel sinks. Is laid, and underground of soft ground where subsidence of the soil layer is not allowed,
It was considered impossible to lay tunnels using the mud pressure shield method. 1 and 2 show an example of a conventional mud pressure shield machine. FIG. 1 is a schematic explanatory view showing an example of equipment of a mud pressure shield machine to which a mud pressure shield method is applied, and FIG. 2 is an enlarged view of a main part of the mud pressure shield machine of FIG. The mud pressure shield machine 1 includes a kind of closed shield machine and open shield machine, and injects a slurry as a drilling liquid in order to impart water impermeability and fluidity to excavated earth and sand. The construction method is applied, and the chamber 2 is formed behind a partition 11 provided with a cutting face driven by a motor 16, that is, a cutter 15 on a front surface. In the chamber 2, a stirring blade 14 for kneading the excavated earth and sand excavated by the cutter 15 and the slurry, and a motor 17 for sending the kneaded material, ie, the mud, out of the chamber 2.
A screw conveyor 13 and the like driven by.

In the mud pressure shield machine 1, when the excavated earth in the chamber 2 is positively pressurized by the pressurizing means, the earth pressure of the earth itself or the earth pressure applied by the excavated earth may be applied. is there. The chamber 2 is provided with a slurry inlet 12 for injecting the slurry.
The injection amount of this slurry is adjusted from the dispersion liquid storage tank 6 through a slurry flow 9 by a slurry pump 9 through a control valve 20, and is injected into the chamber 2 from the slurry inlet 12. If necessary, water can be mixed, diluted and injected from the water injection pipe 7. On the other hand, the excavated earth and sand excavated by the cutter 15 is mixed with the slurry injected into the chamber 2 by the agitating blades 14, and is discharged from the chamber 2 in a preferable state, that is, appropriate fluidity, water impermeability, ie, water stoppage, and residual soil treatment. Made in mud which is good for sex.

[0004] The mud filled in the chamber 2 generates mud pressure in the mud in the chamber 2 by the thrust generated by the operation of the shield jack 22, and the mud pressure opposes the sediment pressure and the water pressure acting on the cutter 15. Excavating and discharging the mud pressure shield machine 1. The mud generated by mixing the excavated earth and sand with the mud
Is placed on a belt conveyor 3 provided outside the chamber 2 by a screw conveyor 13 arranged in a housing 23 constituting a part of the housing 23, is carried to a wellhead by a shear steel wheel 21 or the like, and then passes through the excavated sediment flow 4. The mud is carried out to the outside mud hopper 5, and the mud is carried away from the mud hopper 5 to a predetermined place by a dump truck 8 or the like. In the figure, reference numeral 18 denotes a case jack.

[0005] When shield excavation of the ground using the above-mentioned mud pressure shield method, the composition of the slurry to be kneaded with the excavated soil is basically bentonite mud, and CMC, polycarboxylic acid, naphthalene sulfonic acid / formaldehyde condensate, etc. It is common to add a polyvalent anionic water-soluble polymer.

[0006]

Excavation of the soft soil layer by the conventional shield method has a disadvantage that the soil is displaced after the completion of the tunnel, that is, the soil layer above the tunnel is settled, and it is necessary to bury the subsided surface layer. In cases where refilling is not allowed, the shield method could not be adopted. An object of the present invention is to solve the above problems,
An object of the present invention is to provide a mud pressure shield method for excavating a soft soil layer without causing soil subsidence.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have found that the above problems can be solved by adding a surfactant to conventionally used slurry. It came to be.

According to the first aspect of the present invention, the N value is 0 to 2
This is a shield method for soft soil, characterized by injecting a drilling fluid containing a surfactant into a cutter chamber when excavating a soft soil layer that is 0 by a shield method without causing ground displacement.

According to a second aspect of the present invention, the N value is 0-2.
The soft soil according to claim 1, wherein a drilling fluid containing a surfactant is injected into the cutter chamber when excavating the soft soil layer, which is 0, by a mud pressure shield method without causing a ground shift. It is a shield construction method.

[0010] The invention of claim 3 of the present invention is characterized in that a drilling liquid containing a surfactant and a polyvalent anionic water-soluble polymer is injected into a cutter chamber. Shielding method for soft soil.

The invention of claim 4 of the present invention is characterized in that a drilling liquid containing bentonite, a surfactant and a polyvalent anionic water-soluble polymer is injected into a cutter chamber. Shielding method for soft soil described in (1).

The invention according to claim 5 of the present invention is characterized in that the main component of the surfactant is a nonionic surfactant having an HLB of 6 to 10, and the shield for soft soil according to any one of claims 1 to 4, wherein It is a construction method.

The invention according to claim 6 of the present invention is characterized in that the amount of the surfactant added is 20 g / m ³ or more with respect to the drilling liquid, and is used for soft soil according to claims 1 to 5. It is a shield method.

According to a seventh aspect of the present invention, there is provided the shield method for soft soil according to any one of the first to sixth aspects, wherein the polyvalent anionic water-soluble polymer is a polycarboxylate. .

The invention according to claim 8 of the present invention is characterized in that the amount of the polyvalent anionic water-soluble polymer added to the drilling fluid is 20 g / m ^3.
The above is the shield method for soft soil according to any one of claims 1 to 7.

The invention according to claim 9 of the present invention is the shielding method for soft soil according to any one of claims 1 to 8, wherein the surface tension of the drilling fluid in the air is 35 dyne / cm or less.

A tenth aspect of the present invention is a drilling fluid additive characterized by containing a surfactant, which is used for a shield method.

The invention according to claim 11 of the present invention is the drilling fluid additive according to claim 10, characterized in that it contains a surfactant and is used for a mud pressure shield method.

The twelfth aspect of the present invention is directed to
The drilling fluid additive according to any one of claims 10 to 11, further comprising 10 nonionic surfactants.

A thirteenth aspect of the present invention is the drilling fluid additive according to any one of the tenth to twelfth aspects, comprising a surfactant and a polyvalent anionic water-soluble polymer.

According to a fourteenth aspect of the present invention, there is provided the drilling fluid additive according to any one of the tenth to thirteenth aspects, further comprising a surfactant and a polycarboxylic acid.

According to a fifteenth aspect of the present invention, there is provided the drilling fluid additive according to any one of the tenth to fourteenth aspects, comprising bentonite, a surfactant, and a polyvalent anionic water-soluble polymer. is there.

According to a sixteenth aspect of the present invention, there is provided the drilling fluid additive according to any one of the tenth to fifteenth aspects, comprising a bentonite, a surfactant and a polycarboxylic acid.

[0024]

DETAILED DESCRIPTION OF THE INVENTION A first limitation of the present invention is that an N value is 0.
This is a shield method for soft soil characterized by injecting a drilling fluid containing a surfactant into a cutter chamber when excavating a soft soil layer having a size of ２０20 by a shield method without causing displacement. A second limitation of the present invention is that
For excavating a soft soil layer having an N value of 0 to 20 by a mud pressure shield method without causing a ground shift, a drilling liquid containing a surfactant is injected into a cutter chamber. It is a shield method. A third limitation of the present invention is a soft earth shielding method characterized by injecting a drilling fluid containing a surfactant and a polyanionic water-soluble polymer into a cutter chamber. A fourth limitation of the present invention is a soft earth shielding method characterized by injecting a drilling liquid containing bentonite, a surfactant and a polyvalent anionic water-soluble polymer into a cutter chamber. A fifth limitation of the present invention is a soft earth shielding method, wherein the main component of the surfactant is a nonionic surfactant having an HLB of 6 to 10. A sixth limitation of the present invention is that the amount of surfactant added is 2
This is a soft earth shielding method characterized by being at least 0 g / m ³ . A seventh limitation of the present invention is a soft earth shielding method, wherein the polyvalent anionic water-soluble polymer is a polycarboxylate. An eighth limitation of the present invention is that
This is a soft soil shielding method characterized in that the amount of the polyvalent anionic water-soluble polymer added to the drilling fluid is 20 g / m ³ or more. A ninth limitation of the present invention is a shield method for soft soil, characterized in that the surface tension of the drilling fluid in the air is 35 dyne / cm or less. A tenth limitation of the present invention is a drilling fluid additive containing a surfactant, which is used for a shield method. An eleventh limitation of the present invention is a drilling fluid additive containing a surfactant, which is used for a mud pressure shielding method. A twelfth limitation of the present invention is a drilling fluid additive characterized by containing a nonionic surfactant having an HLB of 6 to 10. A thirteenth limitation of the present invention is a drilling fluid additive characterized by containing a surfactant and a polyvalent anionic water-soluble polymer. A fourteenth limitation of the present invention is a drilling fluid additive characterized by containing a surfactant and a polycarboxylic acid. A fifteenth limitation of the present invention is a drilling fluid additive characterized by containing bentonite, a surfactant and a polyvalent anionic water-soluble polymer. A sixteenth limitation of the present invention is a drilling fluid additive characterized by containing bentonite, a surfactant and a polycarboxylic acid.

The N value is an index indicating the hardness of the soil specified in JIS-A1219. When excavating a soft soil layer with an N value of 20 or less by the shield method, the whole ground is in a state where it is entangled with the cutter, and not only does the cutter torque increase, making excavation difficult, but also in the range around the outer periphery of the cutter chamber. Up until the disturbance occurs, filling the space between the cutter chamber and the segment,
Backfill injection becomes difficult. If the backfill is not sufficiently injected, the volume of the ground constituent particles shrinks due to the rearrangement, and the land subsidence occurs at the top of the tunnel excavated by the shield method. On the other hand, when the non-ionic surfactant of HLB 6 to 10 is present in the drilling fluid used for the shield method and the surface tension is reduced, it penetrates well into the ground in front of the cutter and deflocculates, and only the ground in front of the cutter is excavated and the outer periphery of the cutter chamber is excavated. Backfilling is sufficient without causing disturbance to the ground. There is no disturbance on the ground around the cutter chamber, so no land subsidence occurs. The cutter torque is also normal and excavation can be performed easily.

Although the type of surfactant used in the present invention is not particularly limited, anionic surfactants have high foaming properties, and cationic surfactants react with a dispersant to coagulate excavated earth and sand. Both are not preferred. Desirable surfactants are those containing the nonionic surfactants of HLB 6 to 10 described above, and polyoxyethylene octyl phenol, polyoxypropylene stearate, sorbitan monolaurate and the like have low foaming properties and are preferable. Can be used. The surfactant content in the drilling fluid is 20 g / m ³ or more, and the air surface tension is 35 dyne / cm or less, preferably 30 dyne / c.
m or less, more preferably 29 dyne / cm or less.
Since the surfactant in the drilling fluid is diluted by the mixing of the drilling soil and the drilling fluid, a desirable addition amount is 50.
５００500 g / m ³ .

The method of adding the drilling fluid containing a surfactant and the place of addition are not particularly limited. A solution containing a surfactant may be added alone into the chamber, or a slurry containing a dispersant composed of a polyvalent anionic water-soluble polymer such as CMC, polycarboxylic acid, or a condensate of naphthalenesulfonic acid and formaldehyde. The slurry may be mixed with a surfactant and added to the chamber by a conventional slurry or slurry addition device. Polycarboxylic acids are particularly preferred as dispersants because of their low toxicity. It is preferable to add a dispersant such as polycarboxylic acid so that the funnel viscosity of the slurry or mud injected into the chamber is about 23 seconds. It is common that mud and mud contain bentonite in order to impart water-blocking properties.In the present invention, it is preferable to contain bentonite. Sometimes muddy water is used.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

(Example) In the mud pressure shield method shown in FIGS. 1 and 2, together with bentonite in the dispersion liquid storage tank 6, a polycarboxylic acid [trade name: Syntol B, manufactured by Hymo Co., Ltd., specific gravity 1. 25 ± 0.0
5, appearance: yellow transparent liquid] is added to the slurry to be added in an amount of ⁴ to 6 kg to 1 m ^{3 of} the discharged mud, and at the same time, a surfactant containing polyoxyethylene octylphenol, which is a nonionic surfactant, as a main component [ product name: Shintoru a, Haimo Co., specific gravity 1.05 ± 0.05, appearance; colorless transparent liquid] was adjusted mud was 0.05~0.1Kg added to mud 1 m ³ for discharging . The slurry is sent from the dispersion liquid storage tank 6 to the injection pump 10 provided in the pit via the slurry flow 9 by the slurry pumping pump 19, and the amount of the slurry is adjusted by the control valve 20 through the slurry flow 9 to control the injection amount of the slurry. 12 into chamber 2. The excavation speed when excavating soft ground having an N value of 3 with the cutter 15 is approximately 20 mm / min as in the case of ordinary soil, and the torque of the cutter at the time of excavation is approximately 100 kgf / cm ^{2 by} the hydraulic pressure of the hydraulic motor. The backfill was sufficiently injected, and no subsidence was observed over the long period of the ground above the tunnel.

(Comparative Example) When excavating the same ground as in the example, a slurry having the same composition as that of the example except that Sintitol A was not added was used, and the excavating speed was about 10 mm / min. Is about 150kg /
cm ² , and the backfill implantation had high resistance and was incomplete. The ground above the tunnel sank about 5 cm after one week.

[0031]

According to the shield method for soft soil according to the first aspect of the present invention, the drilling fluid containing a surfactant well penetrates the soil particles of the soft ground and easily deflocculates, and adheres to the cutter of the soft ground. Since only the front of the cutter chamber is excavated, soil particles on the soft ground near the cutter are not affected by disturbance, backfilling is sufficient, and ground subsidence at the top of the tunnel does not occur. Excavation can be performed without changing the cutter torque and the excavation speed as when excavating a normal sand layer or gravel layer. The soft earth shielding method of the present invention can use a conventional shielding machine, is economical because of a simple structure, and has a large effect, and therefore has high industrial utility value.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example of equipment of a mud pressure type shield machine to which a shield method for soft soil according to the present invention is applied.

FIG. 2 is an enlarged view of a main part of the mud pressure shield machine of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mud pressure shield machine 2 Chamber 3 Belt conveyor 4 Excavated earth and sand flow 6 Dispersion liquid storage tank 7 Water injection pipe 8 Dump truck 9 Slurry flow 10 Pump 11 Partition wall 12 Soil inlet 13 Screw conveyor 14 Stirrer blade 15 Cutter 22 Shield jack 23 Housing

Claims (16)

[Claims] 1. Excavation of a soft soil layer having an N value of 0 to 20 by a shield method without causing ground displacement is performed by injecting a drilling fluid containing a surfactant into a cutter chamber. Shielding method for soft soil. 2. Excavation of a soft soil layer having an N value of 0 to 20 using a mud pressure shield method without causing soil displacement involves injecting a drilling fluid containing a surfactant into a cutter chamber. The shield method for soft soil according to claim 1. 3. The shield method for soft soil according to claim 1, wherein a drilling liquid containing a surfactant and a polyvalent anionic water-soluble polymer is injected into the cutter chamber. 4. The shield method for soft soil according to claim 1, wherein a drilling liquid containing bentonite, a surfactant and a polyvalent anionic water-soluble polymer is injected into the cutter chamber. . 5. The surfactant according to claim 1, wherein the main component of the surfactant is a nonionic surfactant having an HLB of 6 to 10.
5. The shield method for soft soil according to claim 4. 6. The amount of the surfactant added to the drilling fluid is 2
Soft mid-season shield tunneling according to claims 1 to 5, characterized in that it is 0 g / m ³ or more. 7. The shielding method for soft soil according to claim 1, wherein the polyvalent anionic water-soluble polymer is a polycarboxylate. 8. The shielding method for soft soil according to claim 1, wherein the amount of the polyvalent anionic water-soluble polymer added is 20 g / m ³ or more based on the drilling fluid. 9. The air surface tension of the drilling fluid is 35 dyne /
The soft earth shielding method according to any one of claims 1 to 8, wherein the diameter is equal to or less than 10 cm. 10. A drilling fluid additive for use in a shield method, comprising a surfactant. 11. A drilling fluid additive according to claim 10, wherein the additive is used for a mud pressure shield method and contains a surfactant. 12. The drilling fluid additive according to claim 10, further comprising a nonionic surfactant having an HLB of 6 to 10. 13. The drilling fluid additive according to claim 10, further comprising a surfactant and a polyvalent anionic water-soluble polymer. 14. The drilling fluid additive according to claim 10, further comprising a surfactant and a polycarboxylic acid. 15. The drilling fluid additive according to claim 10, which comprises bentonite, a surfactant, and a polyvalent anionic water-soluble polymer. 16. The drilling fluid additive according to claim 10, further comprising a bentonite, a surfactant, and a polycarboxylic acid.