JP2598548B2 - Drilling method and apparatus for caisson bottom - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to construction of a railway, bridge, sluice gate or artificial island or other structure to be built in the ocean, lake, marsh and river by caisson method. The present invention relates to an excavation method and an excavation apparatus for excavating an opening of a cylindrical caisson and a ground immediately below the caisson, that is, a bottom of the caisson.

[Prior Art] As a method of excavating the bottom of a caisson, in the case of a construction method in which the inside of a caisson is pressurized with air to prevent water infiltration, conventionally, manual excavation by a worker in a caisson, a machine using an underground tractor shovel and a hydraulic shovel. Excavation was used, but when the water depth at the construction site was large, the pressurization pressure with air was high, and these methods had operational limitations. Underwater excavation will be performed if air pressure is not applied regardless of inundation.In this case, conventionally, a method of excavating with a grab bucket excavator from the upper part of the caisson, a bit for cutting soil and rock Alternatively, a method of excavating by attaching to an arm and rotating it is used.

[Problems to be Solved by the Invention] When laying a foundation by a pneumatic method at a high water depth, it is necessary to increase the air pressure to prevent flooding. Under high pressure, a construction method that requires manned due to problems in human physiology cannot be adopted, and as one construction method, construction will be carried out by underwater excavation without pressurization. In the case of the conventional underwater excavation method, the excavation area of the grab bucket excavator is only directly below the vertical direction. Therefore, depending on the shape of the caisson, it is not possible to excavate below the cutting edge corresponding to the blind spot from the upper part of the caisson. In the method of excavating by rotating the bit, only the range of the bit rotation locus is the excavable area. Therefore, depending on the caisson shape, there is a portion that cannot be covered by the rotation locus. Thus, if there is an excavation residue in the portion corresponding to the bottom surface of the foundation, the load supporting force is impaired.

In order to solve this problem, the present applicant has filed Japanese Patent Application No. 60-2506.
No. 68 (Japanese Patent Publication No. 4-10932) proposed a method and apparatus for excavating just below the caisson wall. The proposal itself is valid,
This is particularly effective when the caisson opening has many flat portions, but is not preferable when there are many curved portions, particularly in the case of a cylindrical caisson.

It is an object of the present invention to provide a method and apparatus for excavating the bottom of a cylindrical caisson that eliminates the inconvenience of the conventional underwater excavation method according to the present invention and that does not leave a non-excavable area.

[Means for Solving the Problems] According to the present invention, a submersible girder is suspended from a portal crane that is pivotally disposed above a cylindrical caisson and fixed to an inner wall surface at a predetermined position below the caisson. Guided vertically from the portal crane to the underwater girder, suspending a plurality of excavators whose excavating diameter of a plurality of drill bits is scalable, expanding the excavating diameter, descending the excavating machine, and opening the caisson opening. When excavating partially, excavating the caisson opening by performing the same excavation by turning the underwater girder sequentially by a predetermined angle,
Lowering the underwater girder and fixing it to the caisson inner wall surface, expanding the excavation diameter, lowering the excavator and performing partial excavation immediately below the caisson to the caisson outer diameter, turning the underwater girder sequentially by a predetermined angle, A method of excavating the bottom of a caisson, in which the same excavation is performed to excavate immediately below the caisson, is provided.

According to the present invention for carrying out the method, a portal crane pivotally disposed on the upper part of the cylindrical caisson;
A submersible girder suspended from the portal crane and freely fixed to the inner wall of a caisson, and a plurality of excavators suspended from the portal crane and vertically guided by the submersible girder are provided. A revolving case in which the excavator is provided with a differential device having a plurality of output shafts connected to a driving source, a hole expanding case supported by the output shaft and rotatable with respect to the revolving case; There is provided a caisson bottom excavating device provided with a drilling diameter expanding / contracting mechanism including a bit shaft provided in a hole case and driven by the output shaft, and a drill bit fixed to an end of the bit shaft.

It is preferable that the number of the bit shafts is, for example, three, two of which are provided with a face cutter-shaped drill bit, and one is provided with a known reverse bit.

[Operation] Therefore, the underwater girder is fixed to the bottom of the caisson opening, and the drilling case is rotated outward with respect to the radius passing through the output axis of the revolving case to increase the diameter of the excavation hole to the outer diameter of the caisson. And excavating the ground at the bottom of the caisson without leaving a blind spot by turning the underwater girder one after another.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

The present embodiment is an example of constructing a bridge foundation over a strait, as shown in FIG. 1, excavating the seabed, installing a cylindrical caisson A on a level surface, and removing the seabed ground inside the caisson. Regarding the work of digging down to a predetermined depth to build a foundation loading surface, an aspect of digging a caisson bottom will be described.

1 to 3, a digging apparatus embodying the present invention includes a portal crane 1 rotatably provided above a caisson A and a hoisting winch 2 of the portal crane 1.
Underwater girder 10 which is suspended from the opening of caisson A by means of suspension wires 3 and 3 and which can be fixed between inner walls, and which is guided by the underwater girder 10 and which is suspended from a hoisting winch 4 at the top of the portal crane. It is roughly composed of two excavators B1 and B2 (henceforth, the symbol B is used when collectively referred to) suspended from the wire 5 so as to be able to move up and down. Note that reference numeral 6 in FIG.
Is a hose adjusting reel of the drainage hose 7 according to the known art along the hanging wire 5.

4 and 5, the underwater girder 10 is provided with a pair of outriggers 11a and 11b at both ends, respectively, so that the underwater girder 10 can be fixed to the inner wall surface of the caisson A. And
From the state where the left outrigger 11a is contracted and the right outrigger 11b is extended as shown in the figure, the outrigger 11a is extended and the outrigger 11b is contracted, so that the underwater beam 10 moves to the right as shown by a two-dot chain line. The shift is performed by the shift amount S. On the inner side of the underwater girder 10, guide rails 12, 12,... Having recessed portions on the left end and the corners of the rectangle at positions slightly to the right of the caisson center CA in the illustrated state are respectively located in the rectangular direction. It protrudes vertically. And on these guide rails 12,
Excavator B is guided by guide plate 21.

The body 20 of the excavator B has a guide plate 2
., And a submersible motor (not shown) is provided inside, and is connected to a revolution case 22 at the lower part of the main body 20.

Referring also to FIG. 6, the revolution case 22 is formed in a triangular box shape, and a differential device (not shown) is provided therein. A hole expansion case rotating shaft 23 is provided at each of the corners of the triangle of the differential device, and a hole expansion case 24 that can be rotated by 180 ° by means not shown is supported on the rotation shaft 23. A face cutter-shaped drill bit 26 is fixed to the bit shaft 25 of two of the hole expansion cases 24, and a known reverse bit 27 is fixed to the bit shaft 25 of the other hole expansion case 24. The members 22 to 27 constitute an excavating diameter expanding / contracting mechanism. The bits 26 and 27 are rotated in the direction of arrow a by the underwater motor. The reaction torque generated in the bits 26 and 27 is interlocked with the differential device, and is replaced by the revolving torque for rotating the revolution case 22 in the direction of the arrow b facing the bit. Therefore,
The torsion moment due to excavation is not generated in the main body 20. The drill bits 26, 26 revolve and revolve, so that the cutting edge draws a trochoid curve optimal for excavation.

With such a configuration, the drilling diameter becomes the minimum drilling diameter Dmin at a position where the bit shaft 25 is located radially inward of the drill center CD. On the other hand, when the hole expanding case 24 is rotated clockwise, for example, by 90 °, the excavation diameter is enlarged to a halfway enlarged excavation diameter Dm as shown in FIG. And expand case 24 to 18
When turned by 0 °, the bit shaft 25 is located outward in the radial direction as shown in FIG. 8, and the excavation diameter is enlarged to the maximum excavation diameter Dmax. This excavation diameter is electrically detected by detecting the rotation angle of the hole expansion case 24 with respect to the revolving case 22 and measured by a measuring device (not shown) at the upper part of the caisson, and the excavation diameter is within a range of the minimum excavation diameter Dmin and the maximum excavation diameter Dmax. Can be arbitrarily scaled and selected.

For excavation, hoisting winch 2 from portal crane 1
Hang the underwater girder 10 from 2, and raise the winch 4,
Excavator guided by underwater girder guide rail 12 by 4
Hang B1 and B2 in synchronization with the underwater girder 10. And the first
As shown in the figure, when descending to a predetermined position of the caisson opening, the outriggers 11a and 11b are extended to the same length, and the center CK of the underwater girder 10 is placed on the inner wall surface of the caisson A so as to coincide with the center CA of the caisson A. Fix it.

Next, the excavator B1 is increased in excavation diameter Dm to be very close to the inner wall surface of the caisson A, and the excavator B2 is excavated in diameter up to the maximum excavation diameter Dmax. The surface is partially excavated to a predetermined depth H, and the excavated slurry is
The water is discharged from the sludge hose 7 to the outside of the caisson A by the reverse bit 27. The sum of the excavation diameter Dm and the maximum excavation diameter Dmax is such that the maximum excavation diameter Dmax and the positions of the centers CB and Cb of the excavators B1 and B2 with respect to the center CK of the underwater girder 10 are larger than the radius R of the caisson A. It is decided. Excavator B
May be set as three, and the sum of the respective excavation diameters may be set to be larger than the radius R.

Next, swivel the portal crane 1 and excavate the underwater girder 10
Turning sequentially in one direction so that Dm slightly overlaps,
Excavation is performed in the same manner as described above to excavate the bottom of the caisson opening.

As shown in FIGS. 4 and 5, in the tapered portion A1 at the bottom of the caisson, one of the outriggers 11b is extended to fix the underwater girder 10, and the excavating diameter of the excavator B1 is reduced by the underwater girder 10
The excavation is performed in the same manner as described above, and the excavation at the bottom of the caisson opening is completed (the completed position is indicated by a horizontal plane in contact with the cutting edges of the bits 26, 26).

Next, the excavator B1 was excavated to a maximum excavation diameter Dmax and partially excavated to the outer diameter of the caisson A. The underwater girder 10 was sequentially turned, and the same excavation as described above was performed. Complete the excavation. If the radius R of the caisson is large and the excavation diameter of the two excavators B1 and B2 causes the remaining excavation in the caisson radial direction on the seabed, the outrigger 11b is contracted, the outrigger 11a is extended, and the underwater beam 10 is moved rightward. Then, the excavation hole is shifted rightward, and the excavation hole is moved to the right to overlap in the radial direction by turning, so that the remaining excavation is eliminated.

[Effects of the Invention] Since the present invention is configured as described above,
The problem of increasing the drilling diameter of the drill bit of the excavator guided vertically in the underwater girder, turning the underwater girder successively and excavating the bottom of the caisson without leaving a blind spot, impairing the load carrying capacity in the conventional method Can be solved.

[Brief description of the drawings]

1, 2, and 3 are front views, top views, and side views showing the entire excavator embodying the present invention, and FIGS. 4 and 5 are front views showing an underwater girder and an excavator. And top view, sixth
FIG. 7, FIG. 7 and FIG. 8 are top views showing the minimum digging diameter state, the halfway digging diameter state, and the maximum digging diameter state for explaining the principle of the excavating diameter expanding / contracting mechanism. A: Caisson, B1, B2 ... Excavator, 1 ... Gate crane, 10 ... Underwater girder, 11a, 11b ... Outrigger, 12 ... Excavator guide rail, 21 ... Guide plate, 22 ... Revolving case, 23 ... Rotating case rotation shaft, 24 ... Expanding case,
25 ... bit axis, 26 ... drill bit, 27 ... reverse bit

Claims (2)

(57) [Claims] An underwater girder is suspended from a portal crane that is pivotally disposed above a cylindrical caisson and fixed to an inner wall surface at a predetermined position below the caisson. The drilling diameter of multiple drill bits is suspended by multiple excavators that can be expanded and contracted, the drilling diameter is enlarged, the excavator is lowered, and the caisson opening is partially excavated, and the underwater girders are sequentially drilled. After excavating the caisson opening by turning at a predetermined angle and performing the same excavation as described above, lower the underwater girder and fix it on the inner wall of the caisson, enlarge the excavation diameter, lower the excavator to the outer diameter of the caisson Excavating directly below the caisson by performing a partial excavation immediately below the caisson, sequentially turning the underwater girder by a predetermined angle, and performing the same excavation as described above. 2. A portal crane pivotally disposed above a cylindrical caisson, a submersible girder suspended from the portal crane and fixed on the inner wall of the caisson, and a lift from the portal crane A revolving case provided with a plurality of excavators freely suspended and guided vertically in the underwater girder, and provided with a differential device having a plurality of output shafts connected to a driving source, A hole expansion case supported by the output shaft and rotatable with respect to the revolution case; a bit shaft provided in the hole expansion case and driven by the output shaft; and a drill bit fixed to an end of the bit shaft. An excavator at the bottom of a caisson, comprising an excavating diameter expanding / contracting mechanism comprising: