JPH10102966A - Excavating equipment of cast-in-place concrete pile hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excavate an optional square cross-sectional pile hole by connecting a bottom part opening square cross-sectional casing to enclose a periphery of a cutter to a lower part of a slip ring supported through a bearing by a flange fixed to a kelly-bar so as to be relatively freely rotatable, and arranging push-cutting blade parts on the lower edge of the casing. SOLUTION: Plural drill bits 22b are arranged in a radial shape on a flange 22a on the tip of a kelly bar 14, and a drill cutter is constituted. A slip ring 30 is supported through a bearing by a fixing flange 28 on a tip part outer periphery of the kelly-bar 14 so as to be relatively freely rotatable, and a bottom part opening cross-sectional square casing 24 to cover a drill cutter is connected to the lower ends of a pair of cylinders 32 connected to its lower part, and push-cutting blade parts 36 and 40 are formed on its lower edge. A cutter projecting to a lower part of the casing 24 precedently excavates a circular cross-sectional hole, and next, the casing 24 is fitted in the ground, and the blade parts 36 and 40 push cut the ground, and a precedently excavated circular cross-sectional periphery is leveled down, and a square cross sectional pile hole is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast-in-place concrete pile hole excavator capable of excavating a pile hole having a square cross section.

[0002]

2. Description of the Related Art In an earth drill method generally used as a method of constructing a cast-in-place pile, drilling is performed by rotating a cutter such as a bucket or a drill.

[0003] For this reason, the cross-sectional shape of a pile hole to be excavated is limited to a circular shape. Therefore, a normal pile is limited to a circular cross-section, and a square cross-section and other square cross-sectional shapes are not formed due to difficulty of excavation. is the current situation.

However, in the case of this circular cross-section, the cross-sectional area becomes the minimum dimension as compared with other cross-sectional shapes.
The following problems occurred due to the relationship between the piles built inside the pile holes and the rectangular pillars connected to the top of the piles, and the relationship between the reinforcing bars built inside the piles.

[0005]

As an example, FIG. 5 shows a case in which a cast-in-place pile 1 is constructed along the boundary of the adjacent land boundary line, and a skeleton column 2 having a square cross section having the same cross-sectional area is constructed above the pile. The radius r of the cast-in-place pile 1 and the length a from the center of the skeleton column when the two have the same cross-sectional area S are given by: radius r = S ^1/2 / π ^1/2 = 0.56S ^{1 / 2} .

On the other hand, the length a = 0.
Since 5S ^1/2 is used, when both surfaces are aligned along the boundary line of the adjacent ground, the center of the column is shifted with respect to the center of the pile as shown in the figure. It was a factor to be expressed.

Further, comparing the same area and the same reinforcing bar amount,
The circular cross section is inferior to the square cross section in rigidity by about 5% and bending strength by about 30%. In addition, since a circular shape has the same area and a minimum perimeter, when the reinforcing bars are arranged at the same pitch, the maximum possible reinforcing bar amount is 13% smaller than that of a square.

The present invention solves the above disadvantages.
Its purpose is to provide a drilling device for a cast-in-place concrete hole pile that can be easily drilled into a rectangular or other square cross-section pile hole while performing drilling work by rotating the drill by attaching it to the tip of an existing drilling machine. To provide.

[0009]

In order to achieve the above object, an invention according to claim 1 of the present invention is provided at a tip of a kelly bar, and a cutter for excavating by rotating the kelly bar, and A slip ring, which is rotatably supported by a fixed flange, is connected to a lower portion of the slip ring, and has a bottom-opened square cross-section casing surrounding the cutter; and a lower edge of the casing. And a blade portion for press cutting.

Therefore, according to the first aspect of the present invention,
A cutter protruding from the lower part of the casing rotates with the rotation of the kelly bar to perform pre-drilling of a hole having a circular cross section, and then the casing is inserted into the ground. The casing has a square cross-section and is rotatably connected to the kelly bar.Therefore, the blade at the tip pushes the ground through the cross-section according to the square shape, and cuts around the previously excavated circular cross-section. While collapsing, a pile hole having the cross-sectional shape is formed.

According to the present invention, the cutter is provided with a drain pipe, the drain pipe is connected to the inside of the kelly bar, and the excavated earth and sand can be discharged to the ground by a reverse circulation method through these pipes. It is characterized by having done.

Therefore, according to the second aspect of the invention, excavated earth and sand can be discharged to the ground without separately providing a drainage pipe. .

According to the third aspect of the present invention,
3. The invention according to claim 1, wherein the bearing member and the casing are connected via a cylinder, and the casing can be moved up and down with respect to the kelly bar in accordance with expansion and contraction of a plunger protruding from the cylinder. And

Therefore, in the third aspect of the present invention, the plunger is immersed during normal excavation work, so that the cutter protrudes from the bottom surface of the casing. A square pile hole is formed by press-cutting, as in claim 1. However, when the plunger is protruded when the cutter has settled at the bottom of the hole, the casing descends with respect to the kelly bar, and the cutter is lowered. Is placed in the casing and the periphery of the bottom of the hole is cut into a square by pressing.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the blade portion is formed at a leading edge of a pair of lid members disposed on both inner wall portions of the casing. Wherein the lid member is connected via a plunger to a second cylinder disposed above both inner side walls of the casing, and the plunger is formed by guide grooves disposed on both sides of each lid member. The lid member is positioned on the inner wall surface of the casing in the retracted state, and is guided to move horizontally to the center of the bottom of the casing in the protruded state.

Therefore, in the invention according to claim 4,
When the plunger is projected when the casing has landed on the bottom of the hole, the two lid members move horizontally while descending, and cover the bottom surface of the casing with the slime at the bottom of the hole removed.

[0017]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
Shows the entire configuration of an earth drilling machine equipped with a drilling device according to the present invention, and a kelly bar 14 is suspended from a crane 12 mounted on a truck 10,
The kelly bar 14 penetrates into the ground E by its own weight by unwinding the wire from the hoist 16, and is arranged at the rear of the truck, passes through the kelly bar 14, and is given a rotational force by a yoke 18 rotated by a power unit (not shown).

Then, the excavator 20 of the present invention provided at the tip of the kelly bar 14 is driven to rotate, and excavation is performed by the cutter at the tip.

FIGS. 2 and 3 show the details of the drilling device 20. The drilling device 20 is connected to the tip of the kelly bar 14 and is rotated by a drill cutter 22 for drilling.
And a casing 24 having a square cross section arranged around the drill cutter 22.

The drill cutter 22 has a plurality of drill bits 22b arranged radially below a disk-shaped flange 22a connected to the tip of the kelly bar 14. The drill bit 22 penetrates into the ground by rotation. A drilling operation is performed with the descent.

The type of cutter may be another type of drill cutter. However, drum cutters are excluded because they do not fit into Kelly Bar.

The casing 24 is closed at an upper portion and opened at a lower surface. A shaft hole 26 is formed at an upper center of the casing 24 to allow the kelly bar 14 to be inserted in a loosely fitted state, and a drill cutter 22 at the tip of the kelly bar 14 is inserted therein. Accommodating.

The casing 24 and the kelly bar 14 are connected by two upper and lower flanges 28 fixed to the outer periphery of the tip of the kelly bar 14 and sandwiched therebetween.
And a slip ring 3 which is rotatably supported relative to the flange 28 via an angular bearing or the like.
0 and a pair of cylinders 32 having tips connected to both lower sides of the slip ring 30. The lower ends of the cylinders 32 are connected to the upper part of the casing 24.

In the figure, the plunger 34 of each cylinder 32 protrudes as much as possible, and in this state, the casing 24 relatively descends to the lower side of the kelly bar 14, so that the drill cutter 22 is completely housed therein. When the plunger 34 is completely immersed in the cylinder 32 from the state shown in the drawing, the casing 24 rises along the kelly bar 14, and the drill cutter 22 relatively moves the casing 2.
4 and excavate the ground ahead.

On the lower edge of the casing 24, a fixed blade portion 36 for pushing and cutting is integrally formed on two opposing sides.
A pair of lid members 38 are symmetrically arranged on the other opposite inner wall surface on the diagonal line, and a blade portion 40 is integrally formed on the lower edge of each of the lid members 38.

The upper end of each lid member 38 is connected to the tip of a plunger 44 of a pair of second cylinders 42 arranged along the inner wall of the casing 24, as shown in FIG. Guide shafts 46 project from both sides of the cover member 38, and each guide shaft 46 has a vertical and inclined portion formed on the other side of the casing 24 engaged with a guide groove 48.

Therefore, when the plunger 44 is immersed, the cover member 38 is moved to the casing 24 as shown in FIG.
Upright in parallel with the inner wall surface of the
4 projecting from the lower edge. When the plunger 44 projects from this state, the lid member 38 is moved obliquely inward as shown in FIG.
Close the bottom opening of the.

The above-mentioned cylinders 32 and 42 are connected to a ground surface control device and the like through a hydraulic hose (not shown).
The above operation is performed by remote control according to the situation.

Reference numeral 50 in the figure denotes a mud pipe connected to the inside of the kelly bar 14. The upper end of the kelly bar 14 is also connected to the upper part of the casing 24 via a coupler 52, and communicates with the inside of the casing 24. It is a drain pipe. These feeding and discharging pipes 50 and 54 communicate with a winding device and a feeding and discharging device (not shown) provided on the ground surface, supply muddy water into the casing 24, and mix a soil and muddy water drilled by the drill cutter 22. For continuous excavation.

Next, a procedure for excavating a cast-in-place concrete pile hole using the excavator having the above configuration will be described with reference to FIG.

First, at the time of general excavation work,
As shown in (a), excavation is performed with the plungers 34, 44 of the cylinders 32, 42 immersed respectively. As a result, the tip of the drill cutter 22 protrudes from the bottom surface of the casing 24, the ground is preliminarily excavated with the rotation of the kelly bar 14 and the operation of penetrating the ground, and then the push-off operation by the blade portions 36 and 40 of the casing 24 is performed.

At the start of excavation at the ground surface,
By positioning the corners of the casing 24 and penetrating the casing 24 to a certain depth, the surroundings of the holes formed by the drill cutter 22 are pushed and cut by the blades 36 and 40 without any subsequent rotation. Dig into it.

When the drill cutter 22 is drilled to a predetermined depth by the above operation and the drill cutter 22 has landed on the bottom of the hole, the rotation and lowering of the kelly bar 14 are stopped, and the plunger 34 of the cylinder 32 is moved as shown in FIG. If it is made to protrude, the casing 24 descends, and completely accommodates the drill cutter 22 therein, and at the same time, digs into a rectangular shape around the lowest position.

After the excavation work, the second cylinder 42
By projecting the plunger 44, the respective lid members 38 are lowered as shown in (c), and are tilted inwardly along the slope of the guide groove 48 while shaving the bottom surface by the blade portion 40, thereby forming the bottom of the hole. The bottom opening of the casing 24 is closed while scooping up the slime mixed with the slime that has stagnated.

Thereafter, the kelly bar 14 is pulled up, the earth and sand is discharged to the ground, and a series of operations are repeated to dig. However, depending on the soil properties of the ground and other conditions, a series of operations including opening and closing of the lid member may be performed. This is based on the so-called reverse circulation method using the above-mentioned mud pipe to discharge earth and sand.

After the excavation is completed, the excavator is lifted up, a steel palanquin is erected in the excavation hole, and concrete is cast, whereby a cast-in-place concrete having a square cross section corresponding to the cross-sectional shape of the casing 24 is obtained. You will get a stake.

As shown in FIG. 3, a dowel pin 60 is provided on the upper surface of the disc-shaped flange 22a of the drill cutter 22, a hole 61 is provided in the upper surface member of the casing 24, and the plunger 34 is extended to the maximum to form a kelly bar. A counter-rotating means is provided which allows the dowel pin 60 to be engaged with the hole 61 by being rotated appropriately. Thereby, the direction of the casing can be finely adjusted from the ground via the kelly bar.

In the embodiment, the casing is moved up and down by the cylinder and the bottom opening is opened and closed. However, it is a matter of course that a square pile hole can be formed without providing any special mechanism. .

[0039]

As is apparent from the above description, in the excavator for cast-in-place concrete pile holes according to the present invention, a pile hole having an arbitrary square cross section other than a circular cross section can be formed. Since a pile can be formed according to the cross-sectional shape of the column to be built at the top, the center of the pile and the center of the column can be completely matched, and problems such as bending stress can be solved.

Further, the present invention has an advantage that a square hole can be easily formed simply by adding an attachment to the tip of a kelly bar of an existing earth drilling machine.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the entire structure of an earth drilling machine equipped with a drilling device according to the present invention at its tip.

FIG. 2 is a partial sectional view of the excavator of the present invention mounted on the machine.

FIG. 3 is a half sectional side view of the same.

4 (a) to 4 (c) are cross-sectional explanatory views showing the operation of the excavator from excavation to landing.

FIG. 5 is an explanatory view showing the connection between a conventional cast-in-place pile and a pillar.

[Explanation of symbols]

 14 Kelly Bar 20 Drilling Equipment 22 Drill Cutter 24 Casing 28 Flange 30 Slip Ring 32 Cylinder 34 Plunger 36 Fixed Blade 38 Lid 40 Blade 42 Second Cylinder 44 Plunger 48 Guide Groove

Claims (4)

[Claims] A cutter provided at a tip of the kelly bar for excavating by rotating the kelly bar; a slip ring supported rotatably on a flange fixed to the kelly bar; and a lower part of the slip ring. An excavating device for a cast-in-place concrete pile hole, comprising: a casing having a square cross section having a bottom opening and surrounding the upper periphery of the cutter, and a blade for pushing and cutting provided on a lower edge of the casing. . 2. The cutter according to claim 1, wherein a drain pipe is provided on the cutter, the drain pipe is connected to the inside of the kelly bar, and excavated earth and sand can be discharged to the ground by a reverse circulation method through the drain pipe. Drilling equipment for cast-in-place concrete piles. 3. The bearing member and the casing are connected via a cylinder, and the casing can be moved up and down with respect to the kelly bar in accordance with expansion and contraction of a plunger protruding from the cylinder. 2. An excavator for cast-in-place concrete pile according to 2. 4. The blade portion is formed at the distal end edge of a pair of lid members arranged on both inner wall portions of the casing, and the lid members are disposed above both inner sidewalls of the casing. The lid is connected to the inner wall surface of the casing while the plunger is immersed by the guide grooves arranged on both sides of each lid member, while being connected to the second cylinder thus set via the plunger. 4. The excavator for cast-in-place concrete pile hole according to claim 3, wherein the excavator is guided to move horizontally to the center of the bottom of the casing.