JP3568708B2 - Shaft excavator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a shaft excavator, and more particularly, to a shaft excavator that excavates the inside and the lower side of a shaft structure using an excavating cutter that can be bent vertically.
[0002]
[Prior art]
FIG. 12 shows an example of a conventional shaft excavator. In this figure, a shaft excavator is installed on a drilling cutter 50 for drilling a ground and a mounting girder 27 on the ground, and rotationally drives the drilling cutter 50 via a kelly bar 24, a drill pipe 23 and a stabilizer 22. A rotary drive device including the rotary table 4 and a press-fitting jack 20 that is installed on the mounting girder 27 and press-fits the shaft structure (caisson) 30 into the ground are provided. The excavating cutter 50 includes a cutter drive shaft 12 connected to the stabilizer 22, a boss 14 provided at a lower end of the cutter drive shaft 12, and a radially pin-connected to the side surface of the boss 14 so as to be vertically bent. , Four expansion arms 10 connected to each of these cutter spokes 51, and an expansion jack coupled to the expansion arm 10 and the cutter drive shaft 12 to open and close the cutter spoke 51. 11 is provided.
[0003]
When excavating the ground with the above-mentioned excavating cutter 50, first, the excavating cutter 50 is expanded so as to have a diameter slightly smaller than the inner circumferential dimension of the caisson 30, and the ground inside the caisson 30 is expanded. Then, the caisson 30 is pressed into the ground with the press-in jack 20. At this time, when the caisson pressure input becomes excessive due to the hard ground, the excavating cutter 50 is expanded by the expanding jack 11 below the blade opening 30a of the caisson 30 so as to be larger than the inner peripheral dimension of the caisson 30. In this state, the caisson 30 is excavated below the cutting opening 30a to reduce the caisson press-in force. Thereafter, the diameter of the excavating cutter 50 is reduced, and the caisson 30 is press-fitted into the ground with the press-in jack 20 again. These steps are repeated to excavate downward.
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned prior art, when excavating the lower side of the cutting edge 30a of the caisson 30 in order to reduce the caisson press input, the reaction force (press-in reaction force) of the ground sharply decreases and the caisson 30 is reduced. May sink under its own weight, and the tip of the cutter spoke 51 may be pinched between the blade 30a of the caisson 30 and the ground. In this case, it is necessary to pull out the digging cutter 50 by reducing the diameter of the digging cutter 50 or pulling up the digging cutter 50 as it is. However, when the tip of the cutter spoke 51 is sandwiched between the cutting edge 30a of the caisson 30 and the ground, it is difficult to reduce the diameter of the excavating cutter 50 or pull it out, and it is difficult to forcibly excavate the excavating cutter 50. When the cutter 50 is pulled out, an excessive force is applied to the expanding arm 10 and the boss 14 that are connected to the cut spokes 51 with pins, and these may be damaged. In this case, it is impossible to repair and reuse the excavating cutter 50, or even if it can be repaired, the repair cost is high and uneconomical.
[0005]
An object of the present invention is to provide a drilling cutter by breaking only the tip portion of the castus spoke when the cutter's spoke of the drilling cutter is sandwiched between the cutting edge of the shaft and the ground due to its own weight sinking of the shaft construction. Is to provide a shaft excavator that can easily pull out the shaft.
[0006]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides an excavating cutter having a cutter driving shaft and a plurality of radial cut-spokes supported at the lower end of the cutter driving shaft so as to be vertically bent. In the vertical shaft excavator for excavating the ground inside and below the shaft construction by the drilling cutter, the tip of the cut-spoke, the other part against the axial downward force of the drilling cutter, Also, a strength-reducing portion having a low strength is provided.
[0007]
In the shaft excavator of the present invention configured as described above, when Kattas spokes are sandwiched between the cutting edge of the shaft structure and the ground by the self-subsidence of the shaft structure, the diameter of the drilling cutter is reduced, Or, when trying to pull out the drilling cutter by pulling up the drilling cutter as it is, the downward force in the axial direction of the drilling cutter acts on the strength-reduced part, so that the lower part of the tip of the cutter spoke is lower than the strength-reduced part. The outer part deforms or breaks first, so that the drilling cutter can be easily pulled out.
[0008]
(2) In the above (1), preferably, the reduced strength portion is provided so as to be located inside the inner surface of the shaft construction.
[0009]
(3) Further, in the above (1), preferably, a tip portion of the cut spoke is formed in a shape having a step portion, and the step portion forms the strength-reduced portion.
[0010]
(4) Further, in the above (1), preferably, a cutout portion may be formed at a tip portion of the cut spoke, and the cutout portion may constitute the reduced strength portion.
[0011]
(5) Further, in the above (1), preferably, the tip portion of the cut-spoke is divided into a spoke body portion and a tip portion, and the strength-reduced portion is provided at a boundary between the spoke body portion and the tip portion. The distal tip portion is welded to the spoke body portion as formed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a first embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, the shaft excavator of the present embodiment includes a cutter 1 for excavation, and the cutter 1 for excavation excavates ground inside and below a caisson 30. The caisson 30 is a circular shaft construction that protects the wall of the shaft excavated by the excavating cutter 1, and is press-fitted by the press-fitting jack 20 installed on the mounting girder 27 on the ground and sinks. A blade 30a is provided at the tip of the caisson 30, and the blade 30a is formed at an acute angle so that the caisson 30 can easily sink.
[0013]
The excavating cutter 1 has a cutter shaft (cutter drive shaft) 12 as shown in FIG. 2, and a boss 14 is provided at a lower end of the cutter shaft 12, and the boss 14 has a center cutter 3 and an expanded cutter. 2 are attached. The center cutter 3 is attached to the lower surface of the boss 14 and excavates the center of the shaft. As shown in FIG. 3, the expanding cutter 2 has ribs 33 that are coupled to four protruding portions 14 a radially attached to the side surface of the boss 14 via pins 34 so as to be vertically bendable. At the tip of each rib 33, a cut spoke 31 is joined by welding. As shown in FIG. 4, the cutter spoke 31 has a cutter bit 32 projecting downward by a predetermined distance.
[0014]
The tip portion X1 of the cut spoke 31 is divided into a spoke body portion 31a and a tip portion 31b, and the tip portion 31b is formed such that a stepped portion Y1 is formed on the surface of the tip portion X1 on the side opposite to the cutter bit 32. Is welded to the spoke body 31a.
[0015]
As can be seen from FIGS. 2 and 3, the cutter spoke 31 is attached so as to be inclined so that the surface on the side of the cutter bit 32 faces slightly downward, and the surface on the side of the cutter bit 32 faces slightly upward. For this reason, when a force acts on the cut-spoke 31 in the axial direction of the excavating cutter 1, a force component perpendicular to this acts on the surface of the cutter bit 32 having the stepped portion Y1 on the side opposite to the cutter bit 32. Stress concentration occurs in the portion Y1. On the other hand, with respect to the upward force in the axial direction and the force in the excavation rotation direction (clockwise direction in FIG. 3) generated during normal excavation, a perpendicular force is applied to the surface on the side opposite to the cutter bit 32 having the stepped portion Y1. The component does not act, and no stress concentration occurs at the step portion Y1. That is, at the tip portion X1 of the cut-spoke 31, a stepped portion Y1 forms a strength-reduced portion Z1 having a lower strength than other portions with respect to the axially downward force of the excavating cutter 1, and the stepped portion Y1 is formed. The structure is such that the strength is not greatly reduced for ordinary excavation.
[0016]
A hydraulic jack 11 is attached to the cutter shaft 12, and the hydraulic jack 11 and each of the cut-spokes 31 are connected by arms 10. As shown in FIG. 5, the hydraulic jack 11 includes a piston portion 11a provided on a cutter shaft 12, a cylinder portion 11b fitted and slid on the piston portion 11a, and a rib provided on the outer periphery of the cylinder portion 11b. 11c. One of the arms 10 is connected to a rib 11c by a pin 16 and the other is connected to a connecting plate 31aa provided on a spoke body portion 31a of the cut spoke 31 by a pin 17. The piston part 11a is formed by using the cutter shaft 12 as a piston rod and a part thereof is made thicker. The cylinder part 11b is composed of a slide cylinder 11d and cylinder ends 11e located at both ends of the slide cylinder 11d. By selectively feeding pressurized oil into the vertically movable spaces 11f and 11g, the cylinder portion 11b can be moved up and down with respect to the piston portion 11a to open and close the drilling cutter 1 including the cut-spoke 31 like an umbrella. .
[0017]
When the catus spoke 31 is maximally expanded by the hydraulic jack 11, the outer diameter of the spoke body portion 31a is slightly smaller than the inner diameter S1 of the caisson 30 as shown by a two-dot chain line in FIG. 3, and the outer diameter of the tip portion 31b. The dimensions are substantially the same as the outer diameter dimension S2 of the caisson 30 as shown by the two-dot chain line in FIG. Therefore, the step portion Y1 provided at the tip portion X1 of the cut spoke 31 is always located inside the inner surface of the caisson 30.
[0018]
Returning to FIG. 1, a stabilizer 22 is installed at the upper end of the cutter shaft 12 to prevent the excavation direction from swinging when excavating the ground with the excavating cutter 1. A drill pipe 23 for lowering the drilling cutter 1 to a deep position by sequentially adding the drill pipe 23 is installed above the stabilizer 22, and a kelly bar 24 is connected to the uppermost drill pipe 23. The excavating cutter 1, the stabilizer 22, the drill pipe 23, and the kelly bar 24 are rotationally driven by a rotary driving device including the rotary table 4 installed on the mounting girder 27.
[0019]
The swivel joint 6 is installed on the kelly bar 24, and the swivel joint 6 is connected to the suction pump 8 via the suction hose 7. The earth and sand excavated by the excavating cutter 1 is sucked from the mud outlet 19 by the suction force of the suction pump 8 as muddy water together with the water filled in the shaft, and the muddy water is supplied to the cutter shaft 12, the stabilizer 22, the drill pipe 23, the kelly bar 24. , And is sucked up to a swivel joint 6, reaches a suction pump 8 through a suction hose 7, and is sent to a muddy water treatment facility (not shown). The mud treatment facility separates the sediment and water and sends only the water back into the shaft.
[0020]
A slip ring 28 for transmitting the state of the excavating cutter 1 (stroke of the hydraulic jack 11 and the like) detected by a sensor (not shown) to the ground as an electric signal is provided above the swivel joint 6. Above 28, a hydraulic rotary joint 29 for sending hydraulic oil from a hydraulic jack power unit (not shown) installed on the ground to the hydraulic jack 11 is provided. The hydraulic rotary joint 29 is provided with a crane 9 that suspends the entire cutter including the drilling cutter 1, the stabilizer 22, the drill pipe 23, and the kelly bar 24. The force that presses the excavating cutter 1 against the ground is the weight of the entire cutter, and the pressing force is adjusted by the lifting force of the crane 9.
[0021]
Excavation steps performed by the shaft excavator according to the present embodiment configured as described above will be described with reference to FIGS. 6 and 7.
When the rotary table 4 is rotated by the hydraulic jack 11 in a state where the expanding cutter 2 is set to an excavating diameter that is slightly smaller than the inner peripheral dimension of the caisson 30 (see FIG. 6A), The torque is transmitted to the drilling cutter 1 via the kelly bar 24, the drill pipe 23, and the stabilizer 22, and the drilling cutter 1 drills the ground inside the caisson 30 downward (FIG. 6B). reference).
[0022]
When the caisson 30 is excavated below the cutting edge 30a (see FIG. 6C), the caisson 3 is pressed into the ground with the press-in jack 20. At this time, if the ground is hard, the press-fit resistance increases, so that the caisson press-fit increases, and it becomes difficult to press-fit with the press-fit jack 20. In this case, the expanding cutter 2 is expanded by the expanding jack 11 below the blade opening 30a of the caisson 30 so as to be larger than the inner peripheral dimension of the caisson 30 (see FIG. 7A). The ground below the cutting edge 30a is excavated downward by the tool cutter 1 to reduce the caisson pressure input (see FIG. 7B). Thereafter, the diameter of the expanding cutter 2 is reduced by the expanding jack 11, and the caisson 3 is press-fitted into the ground again by the press-fitting jack 20.
[0023]
As described above, the caisson 3 is pressed into the ground by the press-in jack 20 while excavating the ground with the excavating cutter 1, and new caissons 3 are sequentially laid on the uppermost caisson 3 (FIG. 7). (C)). Then, when the excavation to the depth corresponding to the length of the kelly bar 24 is completed, the entire cutter is pulled up by the crane 9 and a new drill pipe 23 is connected between the kelly bar 24 and the top drill pipe 23. Then, lower the whole cutter and excavate further.
[0024]
In the above, as shown in FIG. 7, while excavation is being performed in a state where the expanding cutter 2 is expanded so as to be larger than the inner peripheral dimension of the caisson 30, the ground reaction force (press-fit reaction force). The caisson 30 sinks under its own weight due to the rapid decrease of the tip, and the tip portion 31b of the cut-spoke 31 may be caught between the blade 30a of the caisson 30 and the ground. In such a state, the digging cutter 1 can no longer be used for digging. Therefore, the diameter of the expanding cutter 2 is reduced by the hydraulic jack 11, or the digging cutter 1 is pulled up by the crane 9 as it is, and once the digging cutter 1 is It is necessary to pull out and to start over from the excavation inside the caisson 30.
[0025]
At this time, when a normal cut-spoke 51 is used like the cutter 50 shown in FIG. 12, the tip 50 is sandwiched between the blade 30 a of the caisson 30 and the ground. It is difficult to pull out the drilling cutter 50 by reducing its diameter or pulling it up. If the drilling cutter 50 is pulled out forcibly, an excessive force is applied to the expanding arm 10 and the boss 14 which are pin-connected to the cutout spoke 51. May be damaged. In this case, it is impossible to repair and reuse the excavating cutter 50, or even if it can be repaired, the repair cost is high and uneconomical.
[0026]
On the other hand, in the cutter spoke 31 of the cutter 1 of the present embodiment, the stepped portion Y1 is provided at the distal end portion X1 so that the strength of the cutter 1 is lower with respect to the axial downward force of the cutter 1 than other portions. A portion Z1 having reduced strength is formed. For this reason, as shown in FIG. 8, when the diameter of the expanding cutter 2 is reduced by the hydraulic jack 11 in a state (a) in which the tip portion 31 b is sandwiched between the cutting edge 30 a of the caisson 30 and the ground, FIG. The tip portion 31b is deformed or broken first (b), and the diameter of the expanding cutter 2 can be reduced without difficulty (c). Further, as shown in FIG. 9, in a state (a) in which the tip portion 31 b is sandwiched between the blade 30 a of the caisson 30 and the ground, when the excavating cutter 1 is pulled up by the crane 9 as it is, The tip portion 31b is deformed or broken first (b), and the excavating cutter 1 can be pulled up without difficulty (c). As described above, when the cutter 1 is pulled out when the cutter 1 is sandwiched between the cutting edge 30a of the caisson 30 and the ground due to the sinking of the weight of the caisson 30, the tip portion 31b is damaged first. The excavating cutter 1 can be easily pulled out. Therefore, the excavating cutter 1 can be reused at a low repair cost without damaging the expanding arm 10 and the boss 14.
[0027]
Also, since the cut tip spoke 31 was manufactured by joining the tip tip portion 31b to the spoke body portion 31a by welding, a plurality of tip tip portions 31b are prepared in advance as spares, and the cutter of the excavating cutter 1 during excavation is prepared. When the tip 31b of the spoke 31 is damaged, the excavating cutter 1 is simply collected, and the spare tip 31b is simply joined to the spoke body 31a again by welding. Easy.
[0028]
A second embodiment of the present invention will be described with reference to FIG. This embodiment differs from the first embodiment only in the structure of the cut-spoke of the expanding cutter, and is otherwise the same as the first embodiment.
[0029]
As shown in FIG. 10, the cut spoke 31P of this embodiment is divided into a spoke spoke body portion 31a and a tip tip portion 31Pb, and a notch Y2 is formed on the surface of the tip portion X2 of the cut spoke 31P on the side opposite to the cutter bit 32. Is formed, and the tip portion 31Pb is joined to the spoke-spoke body portion 31a by welding. For this reason, a strength reduction portion Z2, which is lower in strength than the other portions with respect to the downward force in the axial direction of the excavating cutter 1, is formed by the notch portion X2 at the tip portion X2 of the cut-spoke 31P, and the notch portion Y2 is formed. The structure is such that the strength is not greatly reduced for ordinary excavation.
[0030]
Therefore, also in the present embodiment, similarly to the first embodiment, when the catus 30 is caught between the cutting edge 30a of the caisson 30 and the ground due to the sinking of the weight of the caisson 30, the excavating cutter 1 is removed. Can be easily pulled out.
[0031]
A third embodiment of the present invention will be described with reference to FIG. This embodiment also differs from the first embodiment only in the structure of the cut-spoke of the expanding cutter, and is otherwise the same as the first embodiment.
[0032]
As shown in FIG. 11, the cut spoke 31Q of the present embodiment is divided into a spoke spoke body portion 31a and a tip portion 31Qb, and the tip tip portion 31Qb is joined to the spoke spoke body portion 31a by welding only on the cutter bit 32 side. Then, a non-welded portion Y3 is formed on the surface on the side opposite to the cutter bit 32. This structure is similar to the case where the cutout portion Y2 is formed as in the second embodiment. That is, the non-welded portion Y3 forms a strength-reduced portion Z3, which is lower in strength than the other portions with respect to the downward force in the axial direction of the excavating cutter 1, at the tip portion X3 of the cut-spoke 31Q, and the non-welded portion thereof. The structure is such that Y3 does not greatly reduce the strength for ordinary excavation.
[0033]
Therefore, also in the present embodiment, similarly to the first embodiment, when the cut-spoke 31Q is sandwiched between the blade 30a of the caisson 30 and the ground due to the sinking of the weight of the caisson 30, the excavating cutter 1 is removed. Can be easily pulled out.
[0034]
In the embodiment described above, the cut-spokes 31; 31P; 31Q of the expanding cutter 2 are formed by welding the tip parts 31b; 31Pb; 31Q to the spoke body part 31a by welding. However, the present invention is not limited to this. For example, the spoke body portion and the tip portion may be integrally formed, and a step portion or a cutout may be formed at the boundary between the spoke body portion and the tip portion.
[0035]
Further, in a state where the tip portions 31b; 31Pb; 31Qb are sandwiched between the cutting edge 30a of the caisson 30 and the ground due to the sinking of the weight of the caisson 30, the diameter of the expanding cutter 2 is reduced, or the excavating cutter 1 is removed. It is assumed that the tip portion 31b; 31Pb; 31Qb is damaged when the tip portion is pulled up as it is. However, the tip portion 31b; 31Pb; The tip portions 31b; 31P; 31Qb may be damaged.
[0036]
In the above-described three embodiments, the entire cutter including the excavating cutter 1 is suspended by the crane 9, but the means for suspending the entire cutter may be, for example, a jack or a winch.
[0037]
【The invention's effect】
According to the present invention, the diameter of the drilling cutter is reduced or the drilling cutter is cut when the cut-spoke of the drilling cutter is sandwiched between the cutting edge of the shaft construction and the ground during the sinking of the shaft construction by its own weight. When pulling out the drilling cutter by pulling it up as it is, the tip of the cut-spoke is broken first, so that the drilling cutter can be easily pulled out. This makes it possible to repair and reuse the excavating cutter at a low cost without damaging the expanding arm, the boss, or the like that is pin-connected to the cut-spoke.
[Brief description of the drawings]
FIG. 1 is a sectional view of a shaft excavator according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of an excavating cutter shown in FIG.
FIG. 3 is a view taken along line III-III in FIG. 2;
FIG. 4 is a top view of the cut-spoke shown in FIG. 3;
FIG. 5 is an enlarged view of a hydraulic jack portion shown in FIG.
FIG. 6 is a diagram showing a state where the excavating cutter shown in FIG. 1 is excavating inside a caisson.
FIG. 7 is a view showing a state where the excavating cutter shown in FIG. 1 is excavating a lower side of a caisson.
FIG. 8 is a view showing a procedure for collecting the excavating cutter by reducing the diameter of the expanding cutter when the expanding cutter shown in FIG. 1 is caught between the caisson blade and the ground.
FIG. 9 is a view showing a procedure for pulling up and collecting the excavating cutter as it is when the expanding cutter shown in FIG. 1 is caught between the caisson blade and the ground.
FIG. 10 is a top view of the cut-spoke of the expanding cutter of the shaft excavator according to the second embodiment of the present invention.
FIG. 11 is a top view of the cut-spoke of the expanding cutter of the shaft excavator according to the third embodiment of the present invention.
FIG. 12 is a sectional view of a conventional shaft excavator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Excavating cutter 2 Expanding cutter 10 Expanding arm 12 Cutter shaft 14 Boss 30 Caisson 30a Blade opening 31 Cutter spoke 31a Spoke body 31b Tip tip 31P Cutter spoke 31Pb Tip tip 31Q Cutter spoke 31Qb Tip tip X1, X2 , X3 Tip portion Y1 Stepped portion Y2 Notch portion Y3 Non-welded portion Z1, Z2, Z3 Reduced strength portion

Claims (5)

An excavating cutter having a cutter driving shaft and a plurality of radial cut-spokes which are supported at the lower end of the cutter driving shaft so as to be freely bent in the vertical direction is provided. In a shaft excavator that excavates mountains,
A shaft excavator, wherein a cut-down portion having a lower strength than another portion with respect to an axially downward force of the drilling cutter is provided at a tip portion of the cut-spoke. The shaft excavator according to claim 1, wherein the reduced strength portion is provided inside the inner surface of the shaft structure. The shaft excavator according to claim 1, wherein a tip portion of the cut spoke is formed into a shape having a step portion, and the strength reduction portion is formed by the step portion. 2. The shaft excavator according to claim 1, wherein a cutout portion is formed at a tip portion of the cut spoke, and the cutout portion forms the strength-reduced portion. 2. The shaft excavator according to claim 1, wherein a tip portion of the cut spoke is divided into a spoke body portion and a tip portion, and the reduced strength portion is formed at a boundary between the spoke body portion and the tip portion. A shaft excavator, wherein a tip portion is welded to a spoke body portion.

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