JPH10331147A - Vibratory compacting device and vibrating rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibratory compacting device and its vibrating rod for use with the rod compaction method, whereby it is possible to eliminate an excessive void water pressure generated by vibration even in the compaction the ground a deep as 10 m or more and to manage without cleaning filter during the compaction. SOLUTION: Using a vibration exciter 6 a vibrating rod 7 is allowed to penetrate for a certain amount and drawn out, and repetition of this cycle generates well compacted ground. The subsoil water produced owing to the excessive void water pressure at this time is sucked by a water jet pump, which allows tamping of a deep place in the ground effectively. Small grains having flowed in eventually from the opening 14 of the water suction pipe 8 of the pump will be sent to upon the ground together with the jet water circulating with a high pressure, so that no clogging will be generated in the water suction part, and no filter should necessarily be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration compaction apparatus and a vibration compaction method for compacting a soft ground which is liable to be liquefied by an earthquake, such as a ground, especially a saturated loose sand, by vibration. And a vibration rod.

[0002]

2. Description of the Related Art In the effective use of soft ground such as an artificial landfill, it is common practice to improve the soft ground so as to increase the resistance to liquefaction and the support capacity of the ground. The rod compaction method is one of such ground improvement methods, after inserting a vibration rod into the ground,
The ground is compacted by vibrating the vibrating rod vertically, for example, up and down. At this time, the sand near the vibrating rod is densely packed by vibration, and the space where the groundwater was present tends to shrink, so excessive pore water pressure is generated, the bonding force between the sands is weakened, and the ground around the vibrating rod is May liquefy. Therefore, a drain pipe is provided around the vibrating rod, and water generated around the vibrating rod is sucked up from the drain pipe using a vacuum pump or the like.

[0003] Since a vacuum pump uses vacuum pressure to draw up water, its pumping capacity is limited to about 10 m. When compacting a deep section of 10 m or more, water generated around the vibrating rod must be drained. Was difficult. In addition, when water is sucked up from the water absorption pipe using a vacuum pump, it is difficult to avoid that the water absorption pipe is clogged due to, for example, a filter provided in a water suction port of the water absorption pipe being clogged with fine particles. As a result, the water absorption capacity is reduced, making it difficult to compact the vibrator while removing excessive pore water pressure. In such a case, it is necessary to clean the water-absorbing section, and the construction efficiency is significantly reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration compaction apparatus which can eliminate excessive pore water pressure generated by vibration even in the compaction of a deep portion of a depth of 10 m or more in the rod compaction method. It is to provide a vibrating rod for a vibratory compaction device. It is also an object of the present invention to provide a vibration compaction device and a vibration rod for the vibration compaction device that do not require cleaning of the filter during the vibration compaction operation.

[0005]

In order to solve the above-mentioned problems, an invention according to claim 1 is a vibration compaction device, comprising: a vibration rod attached to a lower portion of a vibrator; It is characterized by comprising a water absorption pipe provided and a water jet pump for absorbing water from an opening provided in the water absorption pipe.

As described above, the vibration rod includes the vibration rod attached to the lower portion of the exciter, the water absorption pipe attached near the vibration rod, and the water jet pump for absorbing water from the opening provided in the water absorption pipe. When compacting the ground by vibrating the vibrating rod attached to the vibration exciter, the vibrating rod around the vibrating rod is liquefied due to excessive pore water pressure generated around the vibrating rod. In some cases, the vibration of the vibrating rod may not be sufficiently transmitted to the ground,
By absorbing the water around the vibrating rod from the opening of the water absorption pipe with a water jet pump, the excessive pore water pressure can be eliminated, and the vibration of the vibrating rod can be effectively applied to the ground. In addition, the pumping capacity of the water jet pump is higher than that of the vacuum pump, and the water around the tip of the vibrating rod can be pumped to the ground even in the case of vibration compaction at a depth of 10 m or more. Further, fine particles such as sand and gravel mixed simultaneously with the water absorption are sent to the ground together with the circulating water flow, so that it is not necessary to provide a filter at the opening for absorbing water, and the water absorbing portion is not blocked.

According to a second aspect of the present invention, there is provided the vibration compaction device according to the first aspect, further comprising a compressed air introduction section for introducing compressed air into the water suction pipe.

As described above, since the water suction pipe is provided with the compressed air introduction portion, in addition to the suction force generated by the jet water flow of the water jet pump, the air lift effect when air rises in the water is utilized. In addition, the water absorption capacity of the water jet pump can be increased.

According to a third aspect of the present invention, there is provided a vibration rod for a vibration compaction device for compacting the ground by vibration, and a part of a water jet pump provided for removing water around the vibration rod. A first water suction pipe for sending a high-pressure water flow toward the nozzle, and a second water suction pipe for sending a jet water flow from the nozzle and water around the vibrating rod to the ground. I have.

As described above, the first water suction pipe, which is a part of the water flow pump and feeds the high-pressure water flow for eliminating the water around the vibrating rod toward the nozzle, and the jet water flow and the water around the vibrating rod are formed. Since the vibration absorption rod and the second water suction pipe to be sent to the ground are provided integrally with the vibration rod, it is generated by vibration by absorbing water around the vibration rod with the water jet pump in the vibration compaction work by the vibration compaction device. Excessive pore water pressure can be eliminated. Furthermore, since the vibration rod and the water absorption pipe are integrated, water near the vibration rod can be reliably absorbed.

According to a fourth aspect of the present invention, there is provided the vibrating rod according to the third aspect, wherein:
It is characterized by having a compressed air introduction part for introducing compressed air in the water supply direction of the second water absorption pipe.

As described above, since the vibrating rod is provided with the compressed air introduction portion for introducing the compressed air in the water supply direction of the second water suction pipe in the vicinity where the nozzle is attached, the vibration compaction operation by the vibration compaction device is performed. In the above, due to the air lift effect in which the compressed air rises in the water absorption pipe, the water absorption capacity of the water injection pump is increased, and water around the vibrating rod can be effectively absorbed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a vibration compaction device and a vibration rod according to the present invention will be described below with reference to FIGS.
It will be described based on. First, FIG. 1 shows a vibration compaction apparatus as an example to which the present invention is applied. FIG. 2 is a view showing a tip portion of the vibrating rod, and FIG. 3 is an enlarged view of a portion B in FIG. In the figure, 1 is a vibration compaction device, 7 is a vibration rod, 8 is a water absorption pipe, 21 is a nozzle, and 23 is a compressed air introduction part.

The vibration compaction device 1 in the present embodiment is
A base vehicle 2 that supports the entire device on the ground, and a leader whose lower end is pivotally supported by the base vehicle 2 and which is raised and lowered almost vertically on the ground by a back stay 3 provided on the base vehicle 2 when the vibration is fastened. 4, an exciter 6 suspended from above the leader 4 by a wire 5 of a crane installed on the base vehicle 2, and movable along the leader 4, and attached below the exciter 6. It roughly comprises a vibrating rod 7 provided, a water absorbing pipe 8 arranged along the longitudinal direction of the vibrating rod 7, a water jet pump for sucking water around the tip of the vibrating rod 7 through the water absorbing pipe 8, and the like. ing.

The vibrator 6 applies a force to the vibrating rod 7 from above when the vibrating rod 7 is pressed into the ground and applies vibration to the vibrating rod 7 when the vibrating rod 7 is vibrated under the ground. is there.

The vibrating rod 7 in this embodiment is shown in FIG.
A part of a water jet pump is disposed on an H-shaped steel 9 as shown in FIG.
, Two water pipe protectors 10a, 10b disposed along the web 9a of the H-shaped steel 9, and a water pipe 8 disposed in the water pipe protectors 10a, 10b.
And a compressed air introduction pipe 15 for sending compressed air from a compressor (not shown) on the ground. The water jet pump according to the present embodiment is provided with the water suction pipe 8.
A nozzle mounting portion described later, a high-pressure pump (not shown) for supplying high-pressure water to the water suction pipe, a water supply-side water tank (not shown) for supplying the circulating water, and the compressed air introduction pipe 15; And the compressor for supplying compressed air.

The water-absorbing pipe 8 is provided with a nozzle mounting portion 2 described later.
At 0, the small-diameter steel pipe 8a and the large-diameter steel pipe 8b are connected to each other. One end of the small-diameter steel pipe 8 a is fixed to an end of the H-shaped steel 9 above the vibrating rod 7,
One of the water pipe protectors 10a is disposed toward the other end of the H-shaped steel 9 and is bent 180 degrees near the end of the H-shaped steel 9 below the vibrating rod 7 so as to be bent by 180 degrees. Has been reached. Further, the small-diameter steel pipe 8a is connected to the large-diameter steel pipe 8b via the nozzle mounting portion 20,
The large-diameter steel pipe 8b is connected to the other water-absorbing pipe protector 10b.
It is guided through the inside to the upper side of the vibrating rod 7.

The nozzle mounting portion 20 is connected to the two steel pipes 8a and 8b by welding, and has a through hole 22 for guiding a high-pressure water flow to the nozzle 21 as shown in FIG.
A compressed air introduction unit 23 connected to the air introduction pipe 15 for introducing compressed air from a compressor (not shown) to the vicinity of the nozzle 21 is provided.

The nozzle 21 is formed of a bolt having a through hole 21a at the center along the screw axis. The nozzle 21 has a screw hole 22a formed in the through hole 22 of the nozzle mounting portion 20 on the jet water flow outlet side. It is screwed and fixed. At the lower end of the large-diameter steel pipe 8b, near the nozzle mounting portion 20, a rectangular opening 14 that is a water intake port is provided.

As shown in FIG. 2, the lower end of the vibrating rod 7 facilitates the penetration and withdrawal of the vibrating rod 7 from the ground, and the water absorption pipe 8 from the resistance in the ground. In order to protect the piercing guide member 11, the cross-section along the line AA in FIG.
12 are attached. This penetrating guide member 11, 1
Two upper and lower members 2 are provided along the longitudinal direction of the vibrating rod 7. The first penetrating guide member 11 is attached with its wedge-shaped sharp ends facing up and down, respectively, so as to cover a portion of the vibrating rod 7 at a substantially lower end portion where the water-absorbing pipe 8 is curved by approximately 180 degrees. A wedge-shaped inclined surface 11a provided below assists in penetrating the vibrating rod 7 downward. The wedge-shaped inclined surface 11b provided on the upper side prevents soil and sand from flowing into the inside of the first penetrating guide member 11. Wedge-shaped inclined surface 1 of first penetrating guide member
Since 1a and 11b receive a large resistance underground, they are specially processed to ensure strength. The second penetrating guide member 12 is mounted slightly above the lower end of the vibrating rod 7. The second penetrating guide member 12 is attached with the specially processed wedge-shaped inclined surface 12a facing upward, and reduces resistance when the vibrating rod 7 is pulled out upward. .. Attached to the lower end of the vibrating rod 7 facilitate the penetration and withdrawal of the vibrating rod 7, and when penetrated, open outwardly as shown in FIG. By reducing it, closing it inward when pulling it out, and closing it inward according to the inflow of surrounding soil when compacting, the tip area during compaction is secured.

The vibration compaction apparatus 1 constructed as described above
The operation of will be described next. First, the base vehicle 2 is installed on the ground, the leader 4 is fixed substantially vertically to the ground, and the vibration rod 7 is pressed into the ground by the vibration exciter 6. After the vibrating rod 7 reaches a predetermined position, the vibration exciter 6
The ground is compacted by repeating a predetermined amount of extraction and penetration of the vibrating rod 7.

Groundwater originally contained in the ground or groundwater derived from excessive pore water pressure generated around the vibrating rod 7 due to vibration is absorbed from underground by the water jet pump.
The high-pressure pump sends a high-pressure water flow from the water-supply-side water tank to the water-absorbing pipe 8 to suck up underground water. The sucked water is returned to the water tank on the water supply side, and circulates through the water suction pipe 8 again.

As shown in FIGS. 1 to 3, the high-pressure water flow sent from the small-diameter steel pipe 8 a at one end of the water-absorbing pipe 8 toward the nozzle 21 becomes a jet water flow by the nozzle 21, and the jet water flow passes through the opening 14. When passing through, a negative pressure is generated, and the groundwater flowing from the opening 14 is involved and flows into the large-diameter steel pipe 8b. According to the pumping by such a water jet pump, water in a deep part of 10 m or more can be pumped. At the time of this pumping, fine particles in the ground flow together with the groundwater from the opening 14, but since high-pressure water is constantly circulating in the suction pipe 8, the fine particles are sent to the water tank on the ground. Can be Therefore, the water absorption pipe 8 does not block,
Water can be continuously absorbed without clogging without installing a filter in the opening 14 that is normally located underground during the vibration compaction operation. Further, the compressed air fed from the compressed air introduction part 23 is caused to flow simultaneously into the vicinity of the nozzle 21 and the compressed air pushes up the water in the water absorption pipe 8 composed of the large-diameter steel pipe 8b. It is also possible to improve the efficiency of groundwater absorption by the jet pump.

Depending on the ground conditions, such as when the surface layer of the ground for which the ground is to be improved is hard and it is difficult to press-fit the vibrating rod 7 using only the vibrator 6, it is necessary to use a water jet at the time of press-fitting the vibrating rod 7 together. However, the high-pressure water used in the water jet pump can be used as a tip water jet when the vibrating rod 7 penetrates, and then can be diverted to water absorption. In addition, collected groundwater can be used as a water jet.

As described above, the reader 4 attached to the vehicle base 2 is fixed substantially vertically to the ground, and the vibrating rod 7 is pressed into the predetermined position in the ground by the vibrator 6 and then vibrated by the vibrator 6. The compaction of the ground is performed by repeating the predetermined amount of extraction and penetration of the rod 7, but the ground is effectively absorbed even in deep ground by absorbing the groundwater based on the excess pore water pressure generated at this time by a water jet pump. Can be compacted. Further, even if fine particles flow in from the opening 14 of the water suction pipe 8 of the water jet pump, they are transported to the water supply side water tank together with the high-pressure jet water. There is no need to install a filter, and the opening 14 is not blocked. Therefore, it is not necessary to clean the filter which is normally located in the ground, and the vibration compaction operation is not interrupted.

In the above embodiment, the vibrating rod is made of H-shaped steel, but may be made of another material such as a steel pipe. Although the water absorption pipe 8 is formed of steel pipes 8a and 8b, the present invention is not limited to this, and any material may be used as long as it has sufficient strength. Also, the number and the like are not particularly limited. Although the shape of the opening 14 of the water intake port is rectangular, it may be, for example, a slit shape or a stitch shape, or a tube dedicated to water absorption may be separately provided. Not limited to Furthermore, the shape of the compressed air introduction part 23 is not particularly limited. Further, the diameter, shape, etc. of the nozzle 21 are also arbitrary.
Needless to say, the specific detailed structure can be appropriately changed.

<Experimental Example> In order to clarify the effects of water absorption, pumping effect, and compressed air introduction by a water jet pump,
A pumping test using a jet stream was performed while changing the pressure of the compressed air to be introduced. First, Experiment 1 in which the relationship between the pressure of compressed air to be introduced into water (air pressure) and the amount of water absorbed at that time is described. As shown in FIG. 4A, the hose 41 is hung from 20 meters above the water-absorbing water tank 31 filled with water. At one end to be introduced into the water, a water jet pump unit 50, which is a nozzle attachment unit of the present experiment, is provided.
One end of the water jet pump unit 50 is connected to a high pressure hose 43 from a water outlet of the jet water high pressure pump 33. The compressor 34
The air hose 44 from the exhaust port is connected to an air flow meter 35 and a pressure gauge (not shown), and the compressed air sent to the air flow meter 35 and the pressure gauge is supplied to the air hose 4.
5 is introduced into the water jet pump unit 50.

Although not shown in detail, the water jet pump unit 50 includes a nozzle for converting a high-pressure water flow sent from the high-pressure hose 43 into a jet water flow, and a compressed air supplied from the air hose 45 for discharging the compressed air around the nozzle. And a water suction port provided between the nozzle and the compressed air introduction port and the hose 41.

The other end of the hose 41 suspended from above the water tank 31 is connected to the water inlet of the water flow meter 36, and the outlet of the water flow meter 36 is connected to the hose. It is guided to the water tank 30 on the water supply side by 46.
A hose 40 is provided from the water in the water tank 30 to the water inlet of the water flow meter 32, and the outlet of the water meter 32 is connected to the inlet of the high-pressure pump 33 for jet water by the hose 42. Connected to the water outlet.

In the experimental apparatus thus configured, when the jet water high-pressure pump 33 and the compressor 34 are operated, the water supplied from the water supply-side water tank 30 is passed through the high-pressure hose 43 by the jet water high-pressure pump 33. It is sent to the water jet pump unit 50. The water fed into the water jet pump unit 50 is turned into a jet water flow by a nozzle in the water jet pump unit 50, and the jet water flow entrains the water flowing from the water suction port and rises in the hose 41. Further, the compressed air from the compressor 34 is fed into the compressed air inlet of the water jet pump unit 50. This air rises in the hose 41 together with the jet water flow, and absorbs water in the water tank 31 on the water absorption side.

The amount of water absorption (for example, Cl / min) is determined from the amount of water supplied (for example, Al / min) supplied from the water tank 30 to the high-pressure jet water pump 33 from the water flow meter 32.
The total water amount (for example, Bl / min) of the supply water amount and the water absorption amount from the water absorption-side water tank 31 is obtained by the water absorption side flow meter 36, and the difference between the total water amount (Bl / min) and the supply water amount (Al / min) ( (B−A = C) l / min). Alternatively, the amount of water absorption may be determined from the amount of decrease in the water level of the water tank 31 on the water absorption side. Further, the amount of compressed air and the compressed air pressure supplied from the compressor 34 can be known from the air flow meter 35 and the pressure gauge.

FIG. 5 (a) shows that the amount of water supplied by the jet stream is 2
This shows the relationship between the pressure of the compressed air supplied from the compressor 34 and the amount of water absorption when the flow rate is 20 l / min. As is clear from this figure, when the diameter of the compressed air inlet is constant (3.5 mm), the amount of water absorption increases by sending compressed air of an appropriate pressure as compared with the case where compressed air is not sent. I do. In this experiment, the water absorption reached a maximum of 128 l / min, particularly when the pressure of the compressed air was set to about 0.7 kgf / cm ² .

Next, Experiment 2 in which the relationship between the pressure of compressed air introduced into sand (air pressure) and the amount of water absorbed at that time is described. The experimental apparatus used in Experiment 2 has almost the same configuration as that of Experiment 1 as shown in FIG. 4B, but instead of a water tank 31 in Experiment 1, a model made of sand containing water is used. The difference is that the sand ground 60 is used.

An experiment was conducted to examine the amount of water absorption from the model sand ground 60 while the amount of water supplied from the jet stream was kept constant, as in Experiment 1, and the results shown in FIG. 5B were obtained. From this figure, even in the case of absorbing water from the model sand ground 60, as in the case of absorbing water from the underwater, when compressed air of an appropriate pressure is sent under a jet water flow of a constant supply water amount, compressed air is not sent. It can be seen that the amount of water absorption increases as compared with the case in which In this experiment, in particular, the pressure of the compressed air was set to 0.
When the pressure is about 7 kgf / cm ² , the water absorption is 127 l /
Min and max.

From these results, it can be seen that by sending compressed air at an appropriate pressure near the nozzle, the water absorption capacity of the water jet pump can be increased as compared with the case where compressed air is not sent.

[0036]

As described above, according to the vibration compaction device according to the first aspect of the present invention, the excess pore water pressure generated when the exciter is operated to apply vibration to the vibration rod and compact the ground. Is solved by using a water jet pump to absorb groundwater from the opening of a water absorption pipe provided in the vicinity of the vibrating rod. The water around the rod tip can be pumped to the ground. Therefore, the ground can be compacted effectively. In addition, fine particles such as silt and sand mixed with water absorption are sent to the ground together with the circulating high-pressure water flow, so clogging does not occur and openings that will be located underground during vibration compaction work Do not use filters. Therefore, there is no need to interrupt the vibration compaction operation and clean the filter, and the vibration compaction operation can be performed efficiently.

According to the vibration compaction device of the second aspect of the invention, the same effect as that of the vibration compaction device of the first aspect can be obtained, as well as the compressed air for taking air into the water suction pipe. With the introduction section, the water absorption capacity can be increased by sending compressed air from the compressed air introduction section. Therefore, the ground can be compacted more effectively.

According to the vibration rod of the third aspect, the first water suction pipe which is a part of the water jet pump for removing water around the vibration rod and feeds the high pressure water flow toward the nozzle, and the jet water flow And the second water absorption pipe that sends the water around the vibrating rod to the ground is integrated with the vibrating rod, so the water around the vibrating rod is absorbed by the water jet pump during the vibration compaction operation by the vibration compaction device. By doing so, excess pore water pressure generated by vibration can be eliminated. Further, since the vibration rod is integrally provided with the first and second water absorption pipes, water near the vibration rod can be reliably absorbed. Therefore, vibration compaction of the ground can be effectively performed.

According to a fourth aspect of the present invention, there is provided a vibrating rod having a compressed air introduction port for introducing compressed air in a water supply direction of the second water suction pipe near the nozzle. In addition to the effects described in 3 above, in the vibration compaction operation by the vibration compaction device,
Due to the air lift effect in which the compressed air rises in the second water suction pipe, the water absorption capacity of the water injection pump is increased, and water around the vibrating rod can be effectively absorbed. Therefore, vibration compaction of the ground can be effectively performed.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a vibration compaction apparatus as an example to which the present invention is applied.

FIGS. 2A and 2B are views showing a distal end portion of a vibration rod of a vibration compaction device as an example to which the present invention is applied, wherein FIG. 2A is a front view, FIG. 2B is a side view, and FIG. It is sectional drawing in the middle arrow AA line.

FIG. 3 is an enlarged side sectional view of a nozzle mounting portion of a portion B in FIG. 2 (a).

FIG. 4 (a) is an explanatory diagram showing conditions of a water absorption experiment from a water absorption side water tank according to the present invention, and FIG. 4 (b) is an explanatory diagram showing conditions of a water absorption experiment from a model sand ground according to the present invention.

FIG. 5 (a) is an explanatory diagram showing the results of a water absorption experiment from the water absorption side water tank according to the present invention, and FIG. 5 (b) is an explanatory diagram showing the results of a water absorption experiment from the model sand ground according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration compaction apparatus 2 Base vehicle 4 Leader 6 Exciter 7 Vibration rod 8 Water absorption pipe 9 H-shaped steel 14 Opening 20 Nozzle attachment part 21 Nozzle 23 Compressed air introduction part 31 Water absorption side water tank 33 High pressure pump for jet water 34 Compressor 50 Water jet pump 60 model sandy ground

Claims (4)

[Claims] A vibrating rod attached to a lower portion of the exciter, a water absorbing pipe arranged near the vibrating rod, and a water jet pump for absorbing water from an opening provided in the water absorbing pipe. A vibration compaction device, comprising: 2. The vibration compaction device according to claim 1, further comprising a compressed air introduction section for introducing compressed air into the water suction pipe. 3. A vibration rod of a vibration compaction device for compacting a ground by vibration, wherein the vibration rod is a part of a water jet pump provided for removing water around the vibration rod, the high pressure water flow being supplied to a nozzle. A vibrating rod, comprising: a first water-absorbing pipe for feeding water toward the nozzle; and a second water-absorbing pipe for sending jet water from the nozzle and water around the vibrating rod to the ground. 4. The vibrating rod according to claim 3, further comprising: a compressed air introduction section for introducing compressed air in a water supply direction of the second water suction pipe near the nozzle.