JPH0530926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to an improvement of a vibration device for ground improvement used in a rod compaction pile method or the like.

<<Conventional technology>> A vibration device for ground improvement used in the rod compaction pile construction method basically consists of a rod with a mechanical vibrator placed at the top end and a drilling bit installed at the bottom end, and a rod installed above ground. and a leader that guides the rod in the direction of driving into the ground.

The vibrator is manufactured by, for example, the Japanese Patent Publication No. 61-
As shown in Publication No. 22693, by controlling the rotational phase of the eccentric rotating body, the amplitude and its direction are changed, and the entire rod is vibrated at a period corresponding to the rotational period of the rotating body. This structure allows the bits to penetrate underground.

<<Problems to be solved by the invention>> However, especially when this vibrating device was adapted to a gravel ground improvement method, it had the disadvantage that the speed of penetration into the ground was significantly lower.

The reason for this is that the vibration is of low frequency and has a relatively large amplitude, and when the tip of the bit collides with gravel in the ground due to such vibration, rebound is likely to occur, and the vibration in the direction of penetration is likely to occur. This is because stability becomes poor. In addition, when rebound occurs frequently, it not only continuously generates loud noise but also continues to apply shock to the equipment, increasing the probability of failure and reducing the operating rate.

The present invention was made in view of the above problems, and its purpose is to improve the ground by suppressing the occurrence of rebound, improving construction speed and efficiency, reducing noise, and improving the operating rate of equipment. It provides a vibration device for use.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention provides a rod having a mechanical vibrator disposed at the upper end and a drilling bit provided at the lower end, and a rod installed above the ground. A vibrating device for ground improvement comprising a leader that guides the rod in the driving direction into the ground: The drilling bit includes a mounting block fixedly connected to the lower end of the rod, and a mounting block fixedly connected to the lower end of the rod; It is equipped with an anvil connected vertically so as to be able to be slightly displaced, and a vibrator interposed between the anvil and the mounting block, and by causing the vibrator to vibrate, the anvil itself can be adjusted to the vibration period and amplitude of the vibrator. The gist is that the ultrasonic vibrations are applied accordingly.

<<Operation>> The entire pile vibrates at a low frequency with a certain amplitude and period using a mechanical vibrator, and the rod penetrates into the ground while drilling with the bit at the tip, as in the conventional method. Also, when the vibrator is excited,
The anvil itself vibrates ultrasonically and performs the drilling action in advance of the rod. Since this amplitude is small, the hole is drilled while continuously impacting the ground, so even if the tip of the anvil collides with hard gravel, there is little rebound, making it easier for the entire rod to penetrate.

Therefore, by exciting the vibrator and synchronizing it with the mechanical vibrator to perform the penetration work,
It reduces the impact of collision with gravel, suppresses rebound, and allows for faster construction.

<<Example>> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 indicates a leader installed above the ground, and reference numeral 2 indicates a main body of the device which is guided by one side of the leader 1 so as to be movable up and down, and which penetrates the rod 3 into the ground E.

This device main body 2 includes a rod 3 that is guided so as to be raised and lowered by brackets 2a provided above and below the leader 1, a mechanical vibrator 4 provided on the upper part of the rod 3, and a vibrator 4 integrated in the lower part of the rod 3. It consists of a drilling bit 5 and a suspension wire 7 for suspending the device main body 2 above the vibrator 4 via a vibration damping damper 6.

The drilling bit 5 has an internally hollow mounting block 9 which is flange-bonded to the tip of the rod 3 via fixing bolts and nuts 8, and an anvil 10 provided at the lower end of the mounting block 9.
and a plurality of voltage elements 11 constituting a vibrator interposed between the anvil 10 and the mounting block 9.

The mounting block 9 has a plurality of triangular wings 12 on its outer periphery, and between each wing 12 a nozzle hole 13 that communicates the inside and outside is bored downward. The inner side is connected to a compressed air hose 14 piped inside the rod 3.

The compressed air supplied through the hose 14 is then passed through each nozzle hole 13 to the drilling bit 5.
It is designed to blow off water, mud, etc. contained in the excavated ground and prevent moisture from entering into the drilling bit 5.

Further, a recess 9a is formed on the lower surface of the mounting block 9, and the upper surface of each piezoelectric element 11 is fixed to the bottom of this recess 9a.

The anvil 10 is a triangular pyramid-shaped block continuous from each wing 12, and its upper part fits into the recess 9a in a concave-convex manner, and is attached by penetrating the center of the lower surface of the mounting block 9. It is connected to the lower end of the bolt 15. Note that this bonding state is loose, and the anvil 10 can be slightly displaced vertically, and furthermore, its upper surface is joined to the lower surface of the piezoelectric element 11.

In addition, a sealing material 16 and an O-ring 17 are interposed at the joint between the mounting block 9 and the anvil 10 to ensure the sealing performance of the joint, and the joint between the two is provided with a vertical rotation stopper. A rod 18 is interposed to prevent the anvil 10 from rotating during vibration.

Each piezoelectric element 11 is connected to a multicore cable 19 wired inside the rod 3, and by applying an alternating current voltage of a predetermined frequency to each piezoelectric element 11 via this cable 19, the frequency can be changed. Produces ultrasonic vibrations according to the

Therefore, when the piezoelectric element 11 is excited, the anvil 10 coupled thereto vibrates in the vertical direction. The amplitude of this is between bolt 15 and mounting block 9.
The amplitude corresponds to the distance between

Next, the operation of the vibration device for soil improvement with the above configuration will be explained using FIG. 3.

First, as shown in Figure a, the amplitude and period of the mechanical vibrator 4 are low frequency and large, so a sine curve is drawn, and the rod 3 and the drilling bit 5 have a period and amplitude along this curve. It penetrates into the ground while vibrating.

Furthermore, the piezoelectric element 11 generates short-period ultrasonic vibrations, as shown in FIG. 1B, and its amplitude is small.

Therefore, when the rod 3 is penetrated in the single mode of a, a rebound phenomenon occurs when the drilling bit collides with gravel, the stability in the drilling state is reduced, and the impact on the device becomes large.

On the other hand, if the penetration occurs in mode b alone, no rebound phenomenon will occur, but the penetration speed will inevitably be small, but when modes a and b are combined, both waveforms will form as shown in c in the same figure. appears in a superimposed manner, and in addition to the penetration performance of the vibrator 5,
When it collides with hard gravel, it gives continuous slight vibrations, which prevents this kind of rebound phenomenon.

<<Effects>> As explained in detail using the embodiments above, in this invention, the entire pile is vibrated at a low frequency with a certain amplitude and period by a mechanical vibrator, and as in the conventional case, The rod is penetrated into the ground while drilling with the bit at the tip. Furthermore, when the vibrator is excited, the anvil itself vibrates ultrasonically and performs the drilling action first. This amplitude is small and the hole is drilled while continuously impacting the ground, so even if the tip of the anvil collides with hard gravel, no rebound occurs.

Therefore, according to the present invention, by causing the vibrator to vibrate and performing the penetration work in synchronization with the mechanical vibrator, the impact upon collision with gravel can be alleviated and the occurrence of rebound can be suppressed. I can,
When this device is applied to the rod compaction pile construction method on gravel ground, etc., it is possible to improve the penetration speed and efficiency, reduce noise, and improve the operating rate of the device.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the overall configuration of the vibration device for soil improvement according to the present invention, Fig. 2 is a sectional view of the main part of the drilling bit in the same device, and Figs. 3 a to c show the operating mode during penetration. FIG. 1...Reader, 2...Device body, 3...Rod, 4...Mechanical vibrator, 5...Drilling bit, 9...Mounting block, 10...Anvil, 11...Piezoelectric element (vibrator) ).

Claims (1)

[Claims] 1. A rod having a mechanical vibrator disposed at the upper end and a drilling bit at the lower end, and a leader installed above the ground to guide the rod in the direction of driving into the ground. In the vibration device for ground improvement, the drilling bit includes: a mounting block fixedly coupled to the lower end of the pile; an anvil coupled to the lower surface of the mounting block so as to be vertically movable; and the anvil. and a vibrator interposed between the mounting block, and by causing the vibrator to vibrate, the anvil itself is made to vibrate ultrasonically in accordance with the vibration period and amplitude of the vibrator. A vibration device for ground improvement.