JPH0435597B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excavation method for constructing piles.

[Conventional technology]

When creating a large-diameter pile hole, a steel pipe casing 1 with a drilling blade 2 provided at the tip as shown in Fig. 5 is used.
A method (all-casing construction method) is known in which the casing is rotated and press-fitted into the ground, and at the same time, earth and sand inside the casing is discharged using a digging tool such as an earth auger or hammer grab 3.

In this case, if the earth and sand cut by the excavation blade 2 provided at the tip of the casing 1 were collected into the casing 1 or randomly dispersed, it would not be possible to collect the earth and sand into the casing 1 in places with a high groundwater content or where the flow velocity is high ( 100 m to 150 m per hour), it becomes impossible to excavate, and the casing 1 is so tightened that it cannot be pulled out, resulting in a situation where the construction has to be interrupted.

This is because when excavating a stratum with groundwater, the earth and sand inside the casing 1 is discharged to the ground using a hammer grab 3 etc. at the same time as the casing 1 is inserted.
The water level in the hole drops below the groundwater level, and groundwater pushes into the casing 1 as shown by the arrow in Figure 5. At the same time, fine-grained earth and sand are pushed into the clearance on the outer circumferential surface of the casing 1, doubling the frictional resistance. It is from.

Therefore, the inventor previously proposed in Utility Application No. 57-185596 (Utility Model Application No. 59-89183) in which the excavating blades 2 are arranged in such a way that the cutting earth and sand are actively pushed out to the outer periphery of the casing 1. In addition, Utility Application No. 57-185596 (Utility Model Application No. 59-89188) proposed a system in which a turning groove was provided at the lower end of the casing to guide the earth and sand cut by the excavation blade to the casing circumferential surface, where it was consolidated. .

In this way, the hole wall will be made up of compacted excavated soil, reducing the void ratio and creating an impermeable layer. Since the impermeable layer prevents the flow of groundwater and completely prevents the collapse of particles of earth and sand on the hole wall, no frictional resistance is applied to the circumferential surface of the casing.

[Problem to be solved by the invention]

However, when digging into bedrock as a foundation ground, it is extremely difficult to dig compared to ordinary earth and sand, the excavation speed is extremely slow, and the excavation blade at the tip of the casing is severely worn out, making it uneconomical. It is several times to several tens of times larger than general soil, and in overwhelming cases it is sometimes impossible to excavate (rocks with an unconfined compressive strength of 1000 kg or more).

In addition, if a device is used to compact the soil cut by the excavation blade on the outer periphery of the casing as described above, and the rock is implanted as is, the shear of the rock sent to the outer periphery of the casing will exceed the mechanical consolidation limit value. Because of this, it cannot be consolidated like general earth and sand, and the excavation sludge that presses into the rock excavation wall and the outer surface of the casing creates frictional resistance, which may make it impossible to insert or rotate the casing.

The purpose of the present invention is to eliminate the disadvantages of the conventional example,
The frictional resistance applied to the casing not only in general soil up to the foundation ground but also in the rock foundation ground is greatly reduced by the excavation action of the head part that connects to the tip of the casing, reducing wear and tear on the excavation blade for the entire construction work.
In addition, since the excavation speed is high, it is an object of the present invention to provide an excavation method that can streamline construction by shortening the construction period and reducing construction costs.

[Means to solve the problem]

In order to achieve the above object, the present invention consists of a casing and a head connected to the end of the casing via a fitting joint, the head has a double wall structure, a hammer is housed inside, and the striking claw at the tip of the hammer is attached to the tip of the head. The excavating blade is made to protrude from the head surface, and the other part of the head end surface is provided with an excavating blade whose inner end is inclined along the direction of rotation of the casing so that when the casing rotates in the normal direction, the excavated soil comes out to the outer periphery of the casing. , and are arranged in a staggered manner, and the outer circumferential surface of the head has an agitator protrusion in the concave part, a turning groove forming part with a turning groove between them, and a thick wall protruding slightly outward from the casing body. An excavation device is used in which sections are formed in the rolling compaction area, one or several of the protrusions are cut in the middle, and horizontal grooves are formed to allow gravel, etc. to escape, and the excavation casing is kept in place until the foundation ground is reached. The excavation casing is rotated in the normal direction to extrude and compact the earth and sand cut by the excavation blade to the outer periphery of the casing, and after reaching the foundation ground, the excavation casing is reversed, and the hammer is activated to remove the cutting waste made by the striking claw with the excavation blade. The purpose is to feed the liquid into the casing.

[Effect]

According to the present invention, when the casing is rotated normally (clockwise) when excavating general earth and sand up to the foundation ground, the soil cut by the excavation blade at the tip of the head is carried out to the outside of the head, and the soil is removed from the outer periphery of the head. is consolidated to form an impermeable layer. This prevents the flow of groundwater and prevents the collapsing action of particles of earth and sand on the hole wall, so that no frictional resistance is applied to the entire circumferential surface of the casing.

Also, when embedding into rock, the casing is reversed (rotated to the left) and the hammer is activated.

Hard rock is cut by the striking claw of a hammer,
It is possible to excavate without putting any strain on the excavating blade, and the cutting chips are transported by the excavating blade to the head and inside the casing. Furthermore, when rock is excavated with a head, the rock inside the head becomes core-shaped, but the chips get pushed between the core and the head, generate frictional heat due to the rotation of the casing, and the void rate decreases. As the head and core become one, the head and core are often broken as the casing rotates.

Furthermore, the above-mentioned functions are mainly carried out by the head which is joined to the end of the casing via a fitting joint, and in this way it is only necessary to make only the head a special shape, making it possible to make it versatile. can.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, to explain the excavation equipment used in the construction method of the present invention, Fig. 1 is a front view of the main parts, and Fig. 2 is a bottom view of the excavation equipment. 4 consists of a short cylindrical body,
A fitting joint 6 to the casing body 5 is formed at the upper end, and a cutting blade 7 is formed at the tip surface.
to be planted.

As shown in FIG. 2, if the clockwise rotation direction of arrow a is the forward rotation direction of the casing 1, the excavation blade 7 is arranged so as to push the excavated soil to the outer periphery of the casing 1 as shown by arrow b. The inner ends of the casings 1 and 1 are arranged so as to be inclined along the direction of rotation compared to the case where the inner ends thereof are directed toward the center of the casing 1. In the illustrated example, this arrangement is staggered.

The outer circumferential surface of the head 4 is divided into a turning groove forming part with a protrusion 8 as an agitator in the concave part and a turning groove 9 between them, and a rolling part 10 which is thick and projects slightly outward from the casing body 5. Although not shown in the drawings, each pair of swirl groove forming portions and rolling pressure portions 10 were formed to face each other.

The rolling section 10 has a cross-sectional shape tapering in the direction of rotation, and is configured to press excavated earth and sand outward through rotation.

One or more of the protrusions 8 are cut in the middle to form lateral grooves 11 through which gravel and the like can escape.

Furthermore, the casing main body 5 and the head 4 have a double casing structure formed by a double-walled body with a hollow interior, and a plurality of small hammers 12 are built in parallel in this head 4, and their tips are The striking claws 12a are arranged at the distal end surface of the head 4 at a place where the arrangement of the excavating blades 7 is interrupted.

Note that these hammers 12 may be independently operated by air or hydraulic pressure, but the rotational force of the casing 1 is transmitted to the hammer 12 by a transmission mechanism such as a rotating gear or a crank in the casing 1 as the vibration driving force of the hammer 12. It is also possible to use it.

Next, the construction method of the present invention using the above excavation equipment will be explained.

The head 4 is fitted into the casing body 5 via a joint 6 and fixed with bolts.

Although not shown, a chuck mechanism is set to the casing drive section provided on the leader mast of the base machine so as to fix the outer periphery of the casing body, and the chuck mechanism is rotated via a speed reducer by starting the motor. Then, the casing body 5 and its distal head 4 also rotate slowly in one direction.

To excavate general earth and sand up to bedrock as foundation ground, the casing 1 is rotated in the normal direction (to the right) as indicated by arrow a in FIG. 2, and the hammer 12 is not operated.

The lower end surface of the head 4 is cut into the ground with the digging blade 7.
It is cut into the ground.

Cutting earth, sand and stone chips (10 cm to 15 cm) with this excavation blade 7
cm) is pushed out of the head 4 by the drilling blade 7 as shown by arrow b in FIG. Further, the remaining earth and sand rises along the swirl groove 9 and is compacted into the hole wall by the rolling portion 10 and the outer periphery of the casing body 5.

Figure 3 shows this situation.The hole wall 14, which has been compacted with excavated earth and sand in this way, has a reduced void ratio and forms an impermeable layer, which prevents the flow of groundwater and causes the particles of the hole wall earth to collapse. This completely prevents frictional resistance from being applied to the casing surface. Note that the outer diameter of the casing body 5 is 10
mm is small, so it can be used on the hole wall and the outer surface of the casing body 5.
A gap (clearance) of 10mm is created.

In the gap, there is a muddy water layer 1 at the same water level as the groundwater level.
5 is formed naturally, so when the earth and sand in the casing 1 is discharged to the surface using a hammer grab, etc., as shown in Figure 5, the water level in the hole falls below the groundwater level, preventing the so-called heaving phenomenon in which groundwater intrudes into the casing. to reduce frictional resistance.

In this way, the casing 1 is used to excavate, and the earth and sand inside the excavation is discharged with a hammer grab, etc., until the bedrock 16 serving as the foundation ground is excavated. As shown in FIG. It is rotated in the reverse direction, that is, to the left, as shown by the arrow d in the figure, and at the same time the hammer 12 is activated. Each striking claw 12a of the hammer 12 makes hundreds of small strikes against the rock during one rotation of the casing 1.
Although the striking force is very small, it completely breaks down the rock particles. Since the impact is small, it does not transmit vibration or noise to the ground, so it can be used in urban areas.

When the rock mass 16 is excavated with the casing 1 in this manner, a core shape is formed inside the casing 1. The excavated waste 17 conveyed to the inside of the head 4 is sent by the excavation blade 7 as shown by the arrow c in FIG. As a result, frictional heat is generated, the excavated waste 17 is affected by heat, the void ratio decreases (rockification), the casing 1 and the core 18 become integrated, and the core 18 inside the casing is screwed off by the rotational force of the casing 1. There are many things.

If the screw cannot be cut, pull up the casing 1 (bring the tip of the head 4 to the top of the core 18), drop a 2-2.5 ton Monken into the casing 1, destroy the core 18, and then remove it from the ground with a hammer club, etc. to be discharged. Even if Monken is dropped to destroy the core 18 inside the casing 1, the casing 1
Since there is no connection with the surrounding ground, vibrations are not transmitted.

In addition to the above-mentioned use, if a large boulder is hit before reaching the bedrock 16, the hammer 12 will be used in the same way to destroy it.

〔Effect of the invention〕

As described above, the excavation method of the present invention, when excavating general earth and sand up to the foundation ground, consolidates the excavated earth and sand to the outer periphery of the casing. Enables deep excavation even in fast geological formations.

In addition, since a hammer is used to embed roots in the foundation ground made of hard rock, it can be done efficiently without putting any strain on the excavation blade, and excavation sludge does not push into the rock excavation wall surface and the outer surface of the casing. The excavation sludge does not cause frictional resistance, making it impossible to insert or rotate the casing.

As a result, compared to the case of using a conventional excavation casing, the overall excavation speed is faster, the construction period is shortened and economical, and the consumable cost of excavation blades can be significantly reduced, and it is possible to improve the excavation speed from soft ground to hard ground. It is now possible to excavate with the same excavator blade.

Furthermore, since the hammer is housed inside the head, there is no need to worry about noise or vibration.

In particular, when the excavated earth and sand are to be compacted on the outer periphery of the casing as described above, this can be done intensively in the head section, so that the equipment used does not become unnecessarily complicated.

[Brief explanation of drawings]

FIG. 1 is a front view of the main parts of the excavation equipment used in the excavation method of the present invention, FIG. 2 is a top and bottom view of the same, and FIG. FIG. 4 is a longitudinal sectional front view showing the state of excavation in the foundation ground, and FIG. 5 is a longitudinal sectional front view showing a conventional example. DESCRIPTION OF SYMBOLS 1...Casing, 2...Drilling blade, 3...Hammer grab, 4...Head, 5...Casing body, 6...Fitting joint, 7...Drilling blade, 8...Protrusion, 9... Rotating groove, 10... Rolling portion, 11... Horizontal groove, 12... Hammer, 12a... Hitting claw, 14
...Consolidated hole wall, 15...Muddy water layer, 16...
Bedrock, 17...Drilling waste, 18...Core.

Claims (1)

[Claims] 1 Consists of a casing and a head that is connected to the end of the casing via a fitting joint, the head has a double wall structure, a hammer is housed inside, the striking claw at the tip of the hammer protrudes from the tip surface of the head, and the tip surface of the head In other parts of the casing, when the casing rotates in the normal direction, the excavating blades are arranged so that the inner ends thereof are inclined along the direction of rotation of the casing, and the excavating blades are arranged in a staggered manner so that the excavated soil comes out to the outer periphery of the casing. The outer circumferential surface of the head is divided into a turning groove forming part with a protrusion as an agitator in the recess and a turning groove between them, and a thick rolling part protruding slightly outward from the casing body. , Cut one or several of the protrusions in the middle, use an excavator with a horizontal groove to allow gravel, etc. to escape, and rotate the excavation casing in the normal direction until the foundation ground is reached and cut with the excavation blade. The excavation is carried out while extruding and compacting earth and sand to the outer periphery of the casing, and after reaching the foundation ground, the excavation casing is reversed, and a hammer is operated to send the cutting sludge made by the striking claw into the casing with the excavation blade. Excavation method.