JPH0340198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a method for excavating an expanded bottom portion for an expanded bottom pile.

<Prior art> In recent years, in order to increase the bearing capacity of each pile, the so-called expanded-bottom pile construction method, in which the bottom of the pile is widened, has been frequently used. The reason for this is that the bottom of the expanded-bottom pile is wider than the shaft and has a larger base area, so it is possible to effectively utilize the ground reaction force. This is because it has the advantages of reducing the amount of concrete required, reducing the amount of excavated soil, and shortening the construction period.

By the way, when adopting such expanded bottom piles,
There are two methods: drilling with a reverse circulation drill, which does not have a bucket for either the shaft or the expanded bottom part, but which can expand and contract the cutter, and an earth drill, which excavates the shaft at the bottom and allows earth and sand to enter the bucket from below and be discharged. On the other hand, there is a construction method in which the bottom expansion part is excavated with a reverse circulation drill that can expand and contract the cutter.

The method using only the reverse circulation drill mentioned above does not have a bucket for discharging earth and sand, so
It transports sediment using muddy water and is used when excavating deep pits or when the diameter of the pit is large. In other words, in the reverse circulation construction method, muddy water is injected into the excavated shaft to stabilize the shaft wall, the muddy water is circulated by an above-ground pump, and excavated soil must be collected above ground during the circulation process. Therefore, there is a drawback that earth and sand separation equipment is required as ground equipment.

On the other hand, the method using the earth drill has a cutting edge (blade) on the bottom of the bucket for earth and sand discharge, and is used when excavating a shallow pit and the diameter of the pit is relatively small. In other words, with the earth drill method,
The excavated soil is collected from the bottom in a bucket formed in the drill, and the earth drill is lifted from the pit and discharged to the ground. Therefore, the earth drilling method has the advantage of not requiring earth and sand separation equipment. but,
With an earth drill, it is not possible to expand and contract the sides, so it is not possible to excavate the expanded bottom area.

<Object of the invention> Therefore, an object of the present invention is to form the side wall of the bucket on the expandable blade, so that the earth and sand generated by excavation of the expanded bottom part can be put into the bucket and discharged, and the earth and sand and muddy water on the ground can be discharged. An object of the present invention is to provide a method for excavating an expanded bottom part for an expanded bottom pile that eliminates the need for separation equipment.

<Structure of the Invention> In order to achieve the above object, the bottom-expanding excavation method of the present invention includes an upper blade that expands and contracts and a lower blade that expands and contracts at the tip of the main shaft, and the lower blade is configured to close the bucket when closed. Form the side wall, and when expanded, use an excavator that connects to the expanded upper blade, first close the lower blade, expand the upper blade, rotate the main shaft to excavate only the upper part of the expanded bottom part, and then open the lower blade. After the excavated soil is taken into the bucket formed by the above-mentioned upper blade and discharged upward, the lower blade is expanded, and this lower blade allows only the lower part of the expanded bottom part to be continuously connected to the upper part of the expanded bottom part. The excavated earth and sand are taken into the bucket and discharged while excavating the area, and the expanded bottom part is excavated in two stages, an upper and a lower part.

<Examples> Hereinafter, the present invention will be explained in detail with reference to illustrated examples.

Figures 1 and 2 are a partially cutaway front view and a side view of an excavator used in the method of excavating an expanded bottom for expanded-bottom piles, in which 1 is the main shaft, and 2a and 2b are the cylindrical surfaces coaxial with the main shaft 1. opposing cases forming a section, 17;
The center is fixed to the main shaft 1, and the above case 2 is attached to the lower end.
The stabilizer 17 is a drum-shaped stabilizer to which the upper ends of the cases 2a and 2b are fixed, and the diameter of the stabilizer 17 is slightly larger than the cylindrical surfaces of the cases 2a and 2b.
On each side of the lower end of the cases 2a and 2b,
The lower blades 8, 8 are connected to a substantially vertical pin 2, respectively.
Cases 2a and 2b are pivotally connected at 5 and 25 and face each other.
In other words, the second openings 9, 9 can be opened and closed. The shafts 25, 25 on which the two lower blades 8, 8 are pivoted are symmetrical with respect to the main axis 1. The lower blades 8, 8 have a curved shape along a cylindrical surface, and as shown in FIG. 4, the curved concave side of one lower blade 8 is connected to the curved convex side of the other lower blade 8. In addition, both of the lower blades 8, 8 are provided with uneven digging bits 10, 10 at their tips. This drilling bit 10,
10 is adapted to fit into the uneven edges of the opposing cases 2a and 2b.

On the other hand, one end of a downwardly convex disk-shaped bottom cover 14 is attached to the lower end of the one case 2a with a hinge 15, so that it can be opened and closed by operating the opening/closing means 32 provided on the opposite part of the other case 2b. I have to.
A conical projection 30 is protruded from the center of the lower surface of the bottom cover 14, and arc-shaped projections 31, 31, which are convex in a plurality of rotational directions radially extend from the conical projection 30 toward the outer periphery.
(See Figures 5 and 6). Each lower part of the cases 2a and 2b, the lower blade 8,
8 and the bottom lid 14 form a bucket 40.

On the other hand, an upper blade 3 having drilling bits 5, 5 at the outer ends in the radial direction so as to be able to protrude freely between the upper parts of the cases 2a, 2b, that is, from the first openings 4, 4;
There are 3. The upper ends of the upper blades 3, 3 are swingably attached to brackets 19, 19 fixed inside the stabilizer 17 via shafts 20, 20. The upper blade 3 is configured to be able to expand and contract in the radial direction toward the bottom by an upper hydraulic cylinder 6 serving as an upper blade expansion and contraction means. The upper end of the upper hydraulic cylinder 6 is attached via a pin 7 to a bracket 43 provided on the main shaft, and the lower end of the piston rod 6a is attached to a bracket 21 fitted to the main shaft so as to be movable up and down. The bracket 21 and the lower part of the upper blade 3 are connected by a link mechanism 41 consisting of a link 23 and pins 22 and 24. Furthermore, a guide plate 3a is provided at the lower end of the upper blade 3 to project inward for guiding excavated earth and sand to a bucket 40 at the bottom of the case. Therefore, the upper hydraulic cylinder 6
By protruding and retracting the rod 6a, the upper blade 3 can be expanded and contracted in the radial direction via the bracket 21 and the link mechanism 41.

On the other hand, a lower blade expansion/contraction means 51 is provided on the main shaft at a phase of 90 degrees with respect to the hydraulic cylinders 6, 6. The lower blade expanding/retracting means 51 consists of a small stroke auxiliary hydraulic cylinder 11 and a long stroke lower hydraulic cylinder 13 pin-coupled to the lower end of the auxiliary hydraulic cylinder. The piston rod 11a at the upper end of the auxiliary hydraulic cylinder 11 is rotatably attached to the main shaft with a pin 12, and the outer periphery of the tube of the auxiliary hydraulic cylinder 11 is slidably guided by a ring 11c provided on the main shaft. Piston rod 1 at the lower end of the lower hydraulic cylinder 13
The tip of 3a is connected to a bracket 26 fitted to the main shaft 1 so as to be movable up and down. Above bracket 26
and the center portion of the lower blade 8 are connected by a link mechanism 42 consisting of a link 28 and pins 27, 29. The upper hydraulic cylinder 6 and the auxiliary hydraulic cylinder 11 are connected to hydraulic hoses 45, 45 of the same system, and the lower hydraulic cylinder 13 is connected to hydraulic hoses 46, 46' of another system, and both hydraulic hoses 45,
Oil is supplied to 45', 46, and 46' in accordance with the drilling process. That is, when the upper hydraulic cylinder 6 is operated, the upper blades 3, 3 expand in diameter, and at the same time, the rod 1 of the auxiliary hydraulic cylinder
1a protrudes by a certain amount to slightly expand the diameter of the lower blades 8, 8. Furthermore, when hydraulic oil is supplied to the lower hydraulic cylinder 13 and the rod 13a is made to protrude, the bracket 26 and the link mechanism 4
2, the lower blade 8 can be expanded in the radial direction to an arbitrary size.

The expanded bottom section for the expanded bottom pile is excavated as follows using the excavator configured as described above (see Fig. 7).

(a) Prior to excavation, connect the upper end of the main shaft 1 of the bottom-expanding excavator A to the drive shaft (Keriver) 34 with a pin 33 (see Fig. 1). Next, as shown in FIG. 7a, the drive shaft 34 is suspended by a crane or the like, and the bottom-expanding excavator A is lowered to the bottom of the shaft shaft B, which has already been excavated by the earth drill. The shaft shaft B is filled with muddy water C to prevent the shaft wall from collapsing.

(b) While rotating the drive shaft 34 and main shaft 1 (see arrow W in Fig. 1), gradually protrude the rods 6a, 6a of the upper hydraulic cylinders 6, 6 (see arrow X in Fig. 1), and slide the upper part. The upper blade 3,
3 around the pivot points 20, 20, and gradually expands in diameter so as to protrude from the first openings 4, 4 (see arrow Y in FIG. 1, two-dot chain line). Along with this, the excavation bits 5, 5 on the outer surfaces of the upper blades 3, 3 excavate the side wall of the bottom of the shaft shaft B in the shape of a truncated cone as shown in FIG. 4 and is dropped into the bucket 40. During this time, the auxiliary hydraulic cylinder 11,
11 operate simultaneously, and the rods 11a, 11
a slightly protrudes, and the lower blades 8, 8 are connected to the lower hydraulic cylinder 13 and the lower sliding bracket 2.
6. The two drilling bits 1 at the tip are slightly rotated and expanded outward via a pair of link mechanisms 42.
The diameter between 0 and 10 is always equal to the maximum diameter of the case 2, that is, the diameter of the stabilizer 17. Here, the stabilizer 17 has a diameter equal to the excavation diameter of the pile shaft portion. Therefore, when the upper bottom is expanded, the shaft shaft B
There is no space between the side wall and the bucket wall.
All of the excavated earth and sand accompanying the upper bottom expansion is collected into the bucket 40 without falling into the air. The diameter of the bucket 40 is made smaller than the shaft of the shaft so that when the case is pulled up after excavating the expanded bottom part, the muddy water filling the shaft of the pile can easily flow down the shaft. be.

(c) When the excavation of the upper expanded bottom portion D is completed, the rotation of the main shaft 1 is stopped, and the rods of the upper hydraulic cylinders 6, 6 are retracted to move the upper blades 3, 3 into the first opening 4,
Immerse yourself inside 4. Next, the bottom-expanding excavator A is pulled up to the ground together with the drive shaft 34. Since the circumference of the bucket 40 is completely closed by the lower blades 8, 8 and the cases 2a, 2b, earth and sand will not spill from the bucket. Next, the opening/closing means 32 (see FIG. 1) is driven to rotate the bottom cover 14 around the hinge 15 to open the bottom of the bucket, and as shown in FIG. Discharge.

(d) Close the bottom cover 14 and lower the bottom expanding excavator A to the bottom of the shaft shaft B again. Upper blades 3, 3
The rods 13a, 13a of the lower hydraulic cylinders 13, 13 are rotated while the main shaft 1 remains immersed in the openings 4, 4 in the same manner as described in item b above.
gradually protrude the lower sliding bracket 26,
Through the pair of link mechanisms 42, the lower blades 8, 8 are gradually rotated outward around the respective hinges 25, 25 so as to open the second openings 9, 9 (see arrow Z in Fig. 4). ). Along with this, the drilling bits 10, 1 on the tip sides of the lower blades 8, 8
0, the side wall of the bottom of the shaft shaft B is excavated in the shape of a truncated cone connected to the upper enlarged bottom D as shown in FIG. , 9 and into the bucket 40 (see FIG. 4). On the other hand, the bottom cover 14 rotates as shown by the arrow W' in FIG. It is pushed out into the lower enlarged bottom E from between the diameter of the lower blade. When excavation of the predetermined lower bottom expansion portion E is completed, while stopping the rotation of the bucket 40, the rods of the lower hydraulic cylinders 13, 13 are retracted and the lower blades 8, 8 are gradually closed, and the lower blades 8, 8 are used to open the bucket. The excavated earth and sand remaining outside and the slime are collected into the bucket 40.

(e) Finally, pull up the bottom-expanding excavator A to the ground. Then, as shown in FIG. 7e, the bottom cover 14 is opened to discharge the excavated earth and sand accumulated in the bucket 40. In this way, the expanded bottom parts D and E are excavated by excavating the upper expanded bottom part D with the upper blades 3 and 3, and the excavated soil is stored in the bucket 40 and discharged on the ground.
Excavating the lower expanded bottom part E with lower blades 8, 8,
Since the material is stored in a bucket 40 and discharged, and the expanded bottom portion is excavated in two stages, the excavation torque can be reduced.

In the above embodiment, when the upper bottom is expanded, the diameter of the lower blades 8, 8 is always slightly expanded by the auxiliary hydraulic cylinder 11 to be equal to the diameter of the stabilizer 17. In addition, since no void is formed between the shaft shaft side wall and the bucket side wall, and excavated earth and sand caused by the upper bottom expansion do not fall into the void, the case 2 can be driven with a small rotational torque. Furthermore, since the radially arcuate protrusions 31 are provided on the lower surface of the bottom cover, slime at the bottom of the shaft shaft can be removed and stored in the bucket, and slime does not accumulate at the bottom of the excavation shaft.

<Effects of the Invention> As is clear from the above explanation, the method for excavating an expanded bottom part for an expanded bottom pile of the present invention includes providing an expanding/contracting upper blade and an expanding/contracting lower blade at the tip of the main shaft.
The lower blade forms the side wall of the bucket when closed, and when expanded, it connects to the expanded upper blade. Using an excavator, first keep the lower blade closed and rotate the main shaft while expanding the upper blade. to excavate only the upper part of the expanded bottom part, take the excavated soil into the bucket formed by the lower blade, close the upper blade, raise the excavator to the ground and discharge the excavated soil, and then The excavator is lowered into the expanded bottom part again, and the lower blade is rotated and expanded, and the lower blade excavates only the lower part of the expanded bottom part that is continuous to the upper part of the expanded bottom part, and the excavated soil is taken into the bucket. , the excavator is lifted above the ground, the excavated soil is discharged, and the expanded bottom section is excavated in two stages, upper and lower, so the driving rotational torque during excavation can be small, making it possible to downsize the excavation equipment and reduce the bucket load. The excavated earth and sand can be reliably stored inside the shaft, greatly contributing to the efficiency of excavation at the bottom expansion section of the shaft shaft.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of an excavator used in the bottom-expanding excavation method of the present invention, FIG. 2 is a side view of FIG. 1,
3 is a sectional view of FIG. 1, FIG. 4 is a sectional view of FIG. 1, FIG. 5 is a sectional view of FIG. FIG. 7 is a diagram showing the procedure of the above-mentioned bottom-expanding section excavation method. DESCRIPTION OF SYMBOLS 1...Main shaft, 2...Case, 3...Upper blade, 4...First opening, 5...Drilling bit, 6...
...Upper hydraulic cylinder, 8...Lower blade, 9...
...Second opening, 10...Drilling bit, 11...Auxiliary hydraulic cylinder, 13...Lower hydraulic cylinder, 1
4...Bottom lid.

Claims (1)

[Claims] 1. Using an excavator, an upper blade that expands and contracts and a lower blade that expands and contracts are provided at the tip of the main shaft, and the lower blade forms a side wall of the bucket when closed and is continuous with the expanded upper blade when expanded; First, while keeping the lower blade closed, rotate the main shaft while enlarging the upper blade to excavate only the upper part of the expanded bottom part, take the excavated soil into the bucket formed by the lower blade, and then open the upper blade. After closing the excavator and discharging the excavated soil, the excavator is lowered to the expanded bottom part again, and the lower blade is rotated and expanded, and the lower blade continuously spreads the excavated soil to the upper part of the expanded bottom part. It is characterized by excavating only the lower part of the continuous expanded bottom part, taking the excavated soil into the bucket, raising the excavator above the ground and discharging the excavated soil, and excavating the expanded bottom part in two stages, upper and lower. Expanded bottom excavation method for expanded bottom piles.