JPH0460164B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a construction method for cast-in-place concrete piles, and more specifically, to a method for constructing cast-in-place concrete piles. This relates to a construction method that allows the formation of

[Conventional technology and its problems]

A preferred method for constructing concrete piles in the ground is to use ready-made concrete piles, which are driven into the ground and whose tips are supported by the ground.

However, the driving method generates large vibrations and noise, and cannot be used depending on the conditions of the construction site, etc., and now only vibration-free and noise-free methods can be used.

Conventional construction methods for constructing cast-in-place concrete piles without vibration or noise include, for example, drilling a vertical hole underground using a casing and an auger screw, or omitting the casing.
Pressure water is injected to pump up muddy water and a vertical hole is drilled.
It is known that concrete piles are formed underground by inserting reinforcing bars into the vertical holes and then pouring concrete.

By the way, the construction method of constructing concrete piles by drilling a vertical hole in the ground and pouring concrete into the vertical hole is a method in which concrete is poured into fluid conditions such as loose ground, so the tip of the formed pile There is a problem in that it is difficult to fix the tip to the ground, and strong supporting force at the tip cannot be obtained.

Furthermore, drilling a vertical hole underground loosens the surrounding ground, and reforming the ground using industrial waste such as bentonite causes a new problem of soiling the geology.

[Purpose of the invention]

This invention was made in view of the above-mentioned points, and has made it possible to securely fix the tip to the supporting ground, and to place high-quality concrete without loosening the surrounding ground. The purpose is to provide a method for constructing piles.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention attaches a ready-made tip pile and an opening/closing bit that holds the tip pile to the tip of the casing, and rotates the casing containing the rod inside in one direction. When the ready-made tip pile is firmly fixed in the ground, the rod connected to the ready-made tip pile is used as a reaction force to separate the casing from the ready-made tip pile in the pulling direction, and then concrete is inserted into the inside of the casing. While pouring, the rod is reversed and pulled out together with the casing, the tip of the rod stirs the concrete and presses it downward, and the concrete is used to form a concrete pile on the ready-made tip pile. It is.

[Effect]

The casing with the pre-fabricated tip pile attached to the tip is pressed into the ground by pushing and rotating, and when it is confirmed that the pre-fabricated tip pile has settled in the supporting ground, the rod whose tip is connected to the pre-fabricated tip pile is used as a reaction force. The casing is separated from the existing tip pile and the supplied concrete is placed inside the casing.

Furthermore, by reversing the rod and pulling out the rod and casing while stirring the concrete with the tip of the rod, a good concrete pile is constructed in continuity with the ready-made tip pile.

〔Example〕

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

As shown in the figure, a ready-made tip pile 2 that is removably attached to the tip of a cylindrical casing 1 is made of concrete and has a sharp point, and is provided with a drilling fluid spout hole 3 that penetrates from the center of the upper surface to the outer periphery of the tip. It is being Incidentally, the tip pile 2 may have an uneven bit directly provided on its tip surface.

Although not shown in the figure, a clutch mechanism 4 is provided at the fitting connection portion between the tip of the casing 1 and the upper end of the tip pile 2.
When the casing 1 rotates in the forward direction, the tip pile 2 also rotates in the same direction, and when the casing 1 rotates in the forward direction, the engagement is released, and by pulling out the casing 1, the tip pile 2 rotates in the same direction.
The casing 1 can be removed from the casing 1.

A cylindrical reinforcing bar cage 5 that is housed in the casing 1 is fixed to the tip pile 2, and a plurality of opening/closing bits 6 are attached to the tip of the casing 1 so as to extend along the outside of the tip pile 2.

In the case of the examples shown in FIGS. 1 and 4, the opening/closing bit 6 is constructed by connecting a plurality of arms 6a with pins 6b so as to be bendable, and folds along the tip pile 2 and casing 1. It can be freely extended along the axial direction. The shape and structure of the opening/closing bit 6 may be freely selected depending on the soil quality and the like.

The hollow rod 7 inserted into the inside of the casing 1 has its tip overlapped with the top surface of the ready-made tip pile 2, so that the inside can communicate with the spout hole 3, and the drilling fluid supplied to the inside of the rod 7 can be exchanged with the ready-made tip pile 2. Tip pile 2
It is designed to be ejected from the distal end surface through the ejection hole 3.

As the drilling fluid, in addition to drilling water, air, various fluids, and mixtures thereof can be used.

The upper ends of the casing 1 and the rod 7 are supported by a drive mechanism 9 attached to the leader 18 of the pile driver so as to be able to move up and down, and the casing 1 and the rod 7 move up and down as the drive mechanism 9 moves up and down. At the same time, forward and reverse rotations are applied to each of them.

The drive mechanism 9 includes an auger motor 10 that provides forward and reverse rotation to each of the casing 1 and the rod 7;
It is composed of a hydraulic cylinder 11 that moves the casing 1 up and down with a predetermined stroke with respect to the drive mechanism 9, and an elevating mechanism 12 that moves the rod 7 up and down with respect to the drive mechanism 9.

FIG. 2 shows an example of a specific structure of the drive mechanism 9. A collar 15 is provided on the outer periphery of a cylinder 14 connected to the upper end of the casing 1 via a joint 13, and this collar 15 is attached to the hydraulic cylinder 11. The casing 1 is rotatably supported by a piston rod 16, and vertical movement is imparted to the casing 1 by expansion and contraction of the hydraulic cylinder 11.

Further, the upper end of a shaft body 17 fitted in the cylinder body 14 so as to be freely movable in the axial direction and rotate integrally with the output shaft of the auger motor 10 is interlocked via a clutch 18, and when the auger motor 10 is started, It is designed to apply rotation to the casing 1.

Further, the auger motor 10 and the rod 7 are also interlocked via a clutch 19, and the elevating mechanism 12 has a hydraulic cylinder or screw type structure.

As shown in Fig. 4, a screw 20 and stirring blades are attached to the outer periphery of the tip of the rod 7, so that the rod 7 rotates in the opposite direction to stir and press the concrete, and the concrete pile to be driven is If it is long, the reinforcing bar cage 5 is added one by one using the intermediate ring 21, and the rod 7 and the casing 1 are
I also try to add more.

Further, although not shown, a drilling fluid supply port and a concrete supply port are provided at the upper ends of the casing 1 and the rod 7.

Next, construction of concrete piles will be explained.

Casing 1 set in front of the pile driver leader
A ready-made tip pile 2 is attached to the lower tip of the tip pile, the opening/closing bit 6 of the casing 1 is aligned with the outer surface of the ready-made tip pile 2, and the lower tip of the rod 7 is connected to the tip pile 2. 2 and casing 1
push it into the ground.

At this time, the auger motor 10 is started to rotate the casing 1 and the ready-made tip pile 2, and a pushing force is applied via the cylinder 11 using the weight of the entire pile driver as a reaction force.
Drilling fluid is ejected from the ejection hole 3.

The casing 1 is pushed in until the ready-made tip pile 2 is fixed to the supporting ground, and the casing 1 is pushed in without loosening the surrounding ground.
The ready-made tip pile 2 can be pushed into the ground.

As a means of confirming that the ready-made tip pile 2 is firmly established in the supporting ground, the changes in the auger motor load current value, the auger motor rotation speed, the pushing time, and the excavation fluid pressure are measured at each depth, and the excavation fluid pressure is measured based on the load current value. Calculate the torque, investigate the correlation between the excavation torque and push-in time, and the N value of the construction ground. Based on these results, estimate the N value of the construction ground and confirm that the ready-made tip pile 2 has settled in the supporting ground. do.

When it is confirmed based on the measured value that the ready-made tip pile 2 has been embedded in the supporting ground by a predetermined amount, the casing 1 is slightly reversed, the clutch mechanism 4 is removed, and the rod 7 connected to the ready-made tip pile 2 is applied as a reaction force. Then, pull up casing 1 with cylinder 11 and remove casing 1.
Separate the tip from the ready-made tip pile 2.

At this time, the ready-made tip pile 2 is pushed down via the rod 7, so there is no possibility that the ready-made tip pile 2 fixed in the ground will float up.

As the casing 1 is pulled up, the tip of the casing 1 is filled with concrete supplied from the upper end of the casing 1.

After concrete has started to be poured, the lifting mechanism 12 is activated to lift the rod 7 to the raised position, and while continuing to pour concrete, the casing 1 and rod 7 are
Turn it around and pull it out.

When the casing 1 is pulled out, the opening/closing bit 6 extends downward, and as the casing 1 rotates, the inner periphery of the casing pull-out hole is shaped, and when the rod 7 is reversed, the screw 2 at the tip
The concrete poured at 0 is stirred and pressed downward.

Therefore, the poured concrete is mixed and stirred,
Homogeneous concrete can be poured into the casing pull-out hole, and by pulling the casing 1 above the ground, a concrete pile A fixed to the supporting ground via the ready-made tip pile 2 is constructed.

〔effect〕

As described above, according to the present invention, since the configuration is as described above, there are the following effects.

() A casing with a ready-made tip pile set at the tip is pushed into the ground, and concrete is cast inside the casing, leaving the tip pile, thereby constructing a concrete pile with high bearing capacity that is anchored in the supporting ground. be able to.

() By pushing the ready-made tip pile, it is possible to construct concrete piles that are anchored to the supporting ground even in fluid conditions such as loose ground.

() By pushing in ready-made tip piles, the supporting ground can be confirmed and the degree of tip anchorage can be reliably controlled.

() By pushing the casing, there is no soil removal and the surrounding ground is not loosened, making it possible to construct concrete piles with high bearing capacity.

() Since the concrete is poured while stirring and pressing downward with the tip of the rod, sufficient concrete can be supplied to the hole in the casing.
Not only can a concrete pile with a uniform overall length be constructed, but also the frictional force generated between the casing and the concrete due to stirring of the concrete can be reduced, and the casing can be pulled out smoothly.

() Since the casing is pushed in and concrete is poured inside, there is no chance of soiling the surrounding ground.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of the construction device used in the construction method of the present invention, Fig. 2 is an enlarged cross-sectional view of the upper part of the same, Fig. 3 is a cross-sectional view taken along the arrow - in Fig. 2, and Fig. 4 is a cross-sectional view taken along the arrow - in Fig. 2. The figure is a vertical cross-sectional view showing the concrete pile in the middle of construction, and Figure 5 is a vertical cross-sectional view of the completed concrete pile. 1... Casing, 2... Ready-made tip pile, 3...
Spout hole, 5... Rebar cage, 6... Opening/closing bit, 7...
... Rod, 10... Auger motor, A... Concrete pile.

Claims (1)

[Claims] 1 Attach a ready-made tip pile and a bit that holds this tip pile to the tip of the casing, press the casing containing the rod inside and press it directly into the ground while rotating in one direction, and push the ready-made tip pile into the ground. Once the rod is fixed, the rod connected to the ready-made tip pile is used as a reaction force to separate the casing from the ready-made tip pile in the pulling direction, and then, while pouring concrete inside the casing, the rod is reversed and pulled out together with the casing. A method for constructing cast-in-place concrete piles, which is characterized in that concrete is stirred and pressed downward at the tip of the pile, and the concrete is used to form a concrete pile on a ready-made tip pile.