JP2005097868A - Casing for shaft excavation, and shaft excavating method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a casing for shaft excavation, which contributes to reduction in frictional resistance between the the natural ground and the cylindrical casing per se, and contributes to stable excavation of a shaft even with a large depth, and to provide a shaft excavating method using the casing. <P>SOLUTION: According to the structure of the casing for the shaft excavation, the cylindrical casing 10-1 has an excavation blade 11 arranged on an undermost portion thereof, which has a cutting edge larger in diameter than the periphery of the cylindrical casing 10-1. Then a feed pipe 12 for high-density slurry is arranged along an inner surface of the cylindrical casing 10 in a longitudinal direction of the same, and the feed pipe 12 has a discharge port 15 at a lower edge thereof, for discharging the high-density slurry toward the periphery of the cylindrical casing 10. According to the shaft excavating method, the cylindrical casing 10 is press-fitted into the natural ground while being rocked or rotated, and by feeding the high-density slurry to the feed pipe 12, the high-density slurry is discharged from the discharge port 15 toward the periphery of the cylindrical casing 10. In this manner a film of the high-density slurry is formed between the natural ground and the cylindrical casing 10, and therefore the excavation is carried out while the frictional resistance is kept reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a shaft excavation casing used in the construction of shafts in sewerage work, underground structure construction work, well excavation work, cast-in-place pile work, and the like.

  When excavating a shaft using a circular casing, a tubing device is connected to a base machine equipped with a power device, a moving device, and a boom, and the circular casing is press-fitted into the ground while swinging or rotating. The circular casing is used by welding or bolting depending on the shaft depth (see, for example, Japanese Patent Laid-Open No. 61-8371 (Patent Document 1)).

  The resistance applied when rocking or rotating into the ground using such a circular casing and press-fitting is divided into the excavation resistance of the excavating blade at the tip of the circular casing and the friction resistance of the outer periphery of the circular casing. The resistance of the excavating blade is determined by the pressure input and the soil quality, and has a substantially constant value during excavation, but the frictional resistance on the outer periphery of the casing is determined by the excavation depth and soil quality and increases as the excavation progresses. In general, sandy soil has a high frictional resistance and tightens a circular casing, so that it often does not move before reaching the target excavation depth. As a countermeasure, it is effective to apply a lubricant such as bentonite to the friction surface. As an emergency measure, the lubricant is poured from the ground onto the friction surface of the circular casing and the ground, but it is difficult to spread the entire surface of the circular casing.

  In order to solve the problem of the conventional shaft excavation method described in Patent Document 1, Japanese Patent Laid-Open No. 11-81847 (Patent Document 2) discloses a lubricant jet on the outer wall of the lowermost circular casing. And a lubricant supply device for a rocking shaft excavator provided with a lubricant supply pipe in each of the other casings. In this method, by injecting a lubricant into the outer periphery of the circular casing, it is possible to reduce peripheral friction due to earth pressure of the circular casing in the case of a shaft having a relatively low depth.

Japanese Patent Laid-Open No. 61-8371 Japanese Patent Laid-Open No. 11-81847

  However, in the case of the conventional method described in Patent Document 2, since the coating of the lubricant covering the outer periphery of the circular casing is thin, in the case of a high-depth shaft, it cannot resist the earth pressure, and the coating is peeled off and the natural ground. The circular casing was in direct contact, the peripheral friction was high, and eventually the casing was unable to swing or rotate.

  Therefore, the present invention reduces the frictional resistance between the circular casing and the natural ground so that the natural ground and the outer periphery of the circular casing are not in direct contact with each other, and the shaft excavation casing capable of stable construction even at a deep shaft. The purpose is to provide a shaft excavation method.

  In order to solve the above problems, the shaft excavation casing of the present invention is provided with a cutting edge having a cutting edge whose diameter is larger than the outer periphery of the cylindrical casing at the lowermost part of the cylindrical casing, and has a high concentration in the vertical direction of the cylindrical casing. A muddy water supply pipe is provided along the inner surface of the cylindrical casing or inside the casing, and discharges high concentration muddy water to the outer peripheral side of the cylindrical casing at least one of the lower part and the middle of the supply pipe. An exit is provided.

  Further, the shaft excavation method of the present invention is a shaft excavation method using the above-mentioned shaft excavation casing, wherein the cylindrical casing is swung or rotated on a natural ground and pressed into the supply pipe with high concentration. By supplying muddy water, high concentration muddy water is discharged from the discharge port to the outer peripheral side of the cylindrical casing, and a high concentration muddy water film is formed between the ground and the cylindrical casing to reduce frictional resistance. The drilling is performed while

  In the present invention, high-concentration mud water is pumped from a discharge port into a gap formed between a natural mountain and a cylindrical casing by rocking or rotating the entire circumference of a cylindrical casing with a shaft excavator and press-fitting it. Drilling against the earth pressure.

  Here, the high-concentration muddy water is a mixture of powdered clay, thickening material, clogging material and water in a predetermined ratio according to the soil quality of the natural ground.

  According to the present invention, the natural ground and the outer periphery of the casing can be in direct contact with each other by pumping high-concentration mud water into the gap formed between the natural ground and the cylindrical casing to counteract the earth pressure of the natural ground. In addition, the friction around the casing can be reduced, and stable construction can be performed even in a deep shaft.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention.
In FIG. 1, a shaft excavator 1 includes a base machine 2 that can travel, a boom 3 that can be turned and raised from the base machine 2, and a hydraulic bucket 4 that is attached to the tip of the boom 3. . A tubing device 6 is fixed to the base machine 2 by a connecting device 5. The tubing device 6 excavates the natural ground 7 while swinging, rotating, and press-fitting a tubular casing 10 made of steel pipe around a central axis, and includes driving devices such as a rotary motor 8 and a press-in cylinder 9. . Sediment and mud in the cylindrical casing 10 excavated by the cylindrical casing 10 are discharged to the ground by the hydraulic bucket 4.

  The cylindrical casing 10 includes a cylindrical casing 10-1 at the tip and intermediate cylindrical casings 10-2, 10-3,... That are added as excavation progresses. A digging blade 11 is attached to the lower end of the cylindrical casing 10-1 at the tip by welding or the like. In this case, the excavating blade 11 has a diameter larger than the outer periphery of the cylindrical casing 10-1, so that a gap is formed between the inner periphery of the hole of the excavated natural ground 7 and the outer periphery of the cylindrical casing 10-1. I have to. When the outer diameter of the excavating blade 11 is the same as the outer diameter of the cylindrical casing 10-1, the inner periphery of the excavated natural ground 7 and the outer periphery of the cylindrical casing 10-1 are in close contact with each other, and friction resistance This is because it becomes larger.

  On the inner periphery of the cylindrical casings 10-1 to 10-3. When connecting with the cylindrical casings 10-1, 10-2, and 10-3, the high-concentration mud supply pipes 12 are connected to each other using the pipe joint 14. A high-concentration mud discharge port 15 is provided at the tip of the high-concentration mud supply pipe 12 to discharge the high-concentration mud toward the outside of the cylindrical casing 10-1.

  A high-concentration mud supply hose 17 is connected to the upper end of the high-concentration mud supply pipe 12 via a swivel joint 16, and the high-concentration mud water 19 stored in the high-concentration mud injection facility 18 is connected to the high-concentration mud supply pipe 12. Pumped at a predetermined pressure. The swivel joint 16 is used for the high-concentration mud supply hose 17 to follow the position of the high-concentration mud supply pipe 12 when the tubular casing 10 is swung or rotated using the tubing device 6. Yes.

Here, the high-concentration muddy water is a mixture of powdered clay, thickener, clogging material and water in a predetermined ratio depending on the soil, and the outer periphery of the cylindrical casing 10 and the inner periphery of the hole of the excavated natural ground 7 It plays the role of reducing the frictional resistance between the two. The proportion of this blending varies depending on the soil quality. For example, in the case of sandy soil having an N value of less than 25, the proportion is about 120 kg of powdered clay, 1.5 kg of thickening material, 8 kg of clogging material, and 942.6 kg of water per 1 m ³ . If the concentration is lower than this, the effect is low on sandy soil. In addition, in the case of viscous soil having an N value of 5 to 25, the ratio is about 120 kg of powdered clay, 0 kg of thickening material, 0 kg of clogging material, and 951 kg of water per 1 m ³ . If the concentration is higher than this, the supply pipe is likely to be clogged, and the supply pressure needs to be increased. The injection pressure of the high-concentration mud water is generally controlled by a lower limit pressure of groundwater 7 +2 tf / m ² and an upper limit pressure of 3-4 tf / m ² . The lower limit pressure is to counter the water pressure, and the upper limit pressure is to prevent jetting to the ground.

A shaft excavation method using the shaft excavation casing according to the embodiment having the above configuration will be described.
First, the cylindrical casing 10-1 at the tip is attached to the tubing device 6, and the ground 7 is moved by the excavating blade 11 at the tip while rotating and press-fitting the cylindrical casing 10-1 using the rotary motor 8 and the press-fitting cylinder 9. Excavate. At this time, the high-concentration mud water 19 stored in the high-concentration mud water injection facility 18 is injected into the high-concentration mud water supply pipe 12 from the swivel joint 16 via the high-concentration mud water supply hose 17 and the high-concentration mud water discharge port 15 at the tip. High-concentration muddy water is discharged to the outer periphery of the cylindrical casing 10-1. Since the cylindrical casing 10-1 is rotated, the high-concentration muddy water discharged from one place spreads over the entire outer periphery of the cylindrical casing 10-1.

  Further, since the excavating blade 11 having a cutting edge larger in diameter than the outer periphery of the cylindrical casing 10-1 is used, immediately after excavation, the inner periphery of the hole of the natural ground 7 excavated by the excavating blade 11 and the cylindrical casing 10-1. A gap is formed between the outer periphery and the high-concentration muddy water easily penetrates. The cylindrical casing 10-1 moves downward as excavation proceeds, and the high-concentration mud discharge port 15 also moves downward along with the excavation. However, since the excavated hole is immobile, the discharged high-concentration mud is The lubricating action between the outer periphery of the cylindrical casing 10-1 to be propelled and the inner periphery of the hole is achieved. The earth and sand inside the excavated cylindrical casing 10-1 is discharged to the outside by the hydraulic bucket 4.

  When the excavation progresses and the upper portion of the cylindrical casing 10-1 is close to the upper portion of the tubing device 6, the next cylindrical casing 10-2 is added, and the high-concentration mud supply pipe 12 is connected by the pipe joint 14 to the upper end thereof. The swivel joint 16 is connected to proceed with excavation. The cylindrical casings 10-3, ... are added according to the depth of the vertical shaft, and excavation is performed to a predetermined depth.

  In this way, the high-concentration mud water is discharged from the high-concentration mud discharge port 15 to the inner periphery of the excavated hole on the outer periphery of the cylindrical casing 10-1, so that the earth and sand of the natural ground 7 and the outer periphery of the cylindrical casing 10-1 are discharged. Therefore, stable construction can be performed even in deep shafts.

(Second Embodiment)
FIG. 2 is a sectional view showing a portion of a shaft excavation casing according to a second embodiment of the present invention. In this embodiment, in addition to the high-concentration mud discharge port 15 provided at the tip of the high-concentration mud supply pipe 12 in the first embodiment, a high-concentration mud discharge port 15 is also provided at an intermediate position of the high-concentration mud supply pipe 12. The point is characteristic. Since the other configuration is the same, the same number is assigned and the description is omitted.

  In the present embodiment, as excavation of the shaft progresses, the gap formed between the inner periphery of the hole excavated by the outer periphery of the cutting blade 11 and the outer periphery of the cylindrical casing 10-1 is an intermediate cylindrical casing 10. The outer periphery of -2 is crushed by the earth pressure and the frictional resistance is increased by the high-concentration mud discharged from the high-concentration mud discharge port 15 provided at an intermediate position.

  This makes it possible to maintain a reduction in frictional resistance when the inner diameter of a hole excavated like sandy soil is difficult to maintain, or when the depth of a shaft is deep.

  In the first and second embodiments described above, an example in which the cylindrical casing 10 is a steel pipe and the high-concentration mud supply pipe 12 is provided on the inner periphery thereof is shown. However, when the cylindrical casing 10 is made of concrete. The high-concentration mud supply pipe can be provided inside the cylindrical casing.

  INDUSTRIAL APPLICABILITY The present invention can be usefully applied as a shaft excavation casing capable of stable construction even in a deep shaft and a shaft excavation method using the same.

1 is an overall configuration diagram showing a first embodiment of the present invention. It is sectional drawing which shows the part of the casing for shaft excavation which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft excavator 2 Base machine 3 Boom 4 Hydraulic bucket 5 Coupling device 6 Tubing device 7 Ground 8 Rotating motor 9 Press-fit cylinder 10, 10-1, 10-2, 10-3 Cylindrical casing 11 Excavation blade 12 High concentration mud Supply pipe 13 Protective cover 14 Fitting 15 High concentration mud discharge port 16 Swivel joint 17 High concentration mud supply hose 18 High concentration mud injection equipment 19 High concentration mud

Claims (3)

  A drilling blade having a cutting edge whose diameter is larger than the outer periphery of the cylindrical casing is provided at the lowermost part of the cylindrical casing, and a high-concentration mud supply pipe is provided along the inner surface of the cylindrical casing in the longitudinal direction of the cylindrical casing, or A shaft excavation casing provided in the casing, and provided with a discharge port for discharging high-concentration mud water on an outer peripheral side of the cylindrical casing at a lower portion of the supply pipe.   The casing for shaft excavation of Claim 1 which provided the discharge port which discharges high concentration muddy water in the outer peripheral side of the said cylindrical casing in the intermediate part of the said supply pipe | tube. A drilling blade having a cutting edge whose diameter is larger than the outer periphery of the cylindrical casing is provided at the lowermost part of the cylindrical casing, and a supply pipe of high-concentration mud water is provided along the inner surface of the cylindrical casing in the vertical direction of the cylindrical casing, or A shaft excavation method using a shaft excavation casing provided in the casing and provided with a discharge port for discharging high-concentration muddy water on the outer peripheral side of the cylindrical casing in at least one of the lower part and the middle of the supply pipe. And
The cylindrical casing is swung or rotated into a natural ground, and the high concentration muddy water is supplied to the supply pipe while being pressed, thereby discharging the high concentration muddy water from the discharge port to the outer peripheral side of the cylindrical casing, A shaft excavation method characterized in that excavation is performed while forming a high-concentration mud water film between a natural ground and the cylindrical casing to reduce frictional resistance.

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