JPH0629511B2 - Sheet pile driving construction method - Google Patents

Description

The present invention relates to a construction method for driving a sheet pile into the ground, and particularly to driving a sheet pile suitable for driving a long and large sheet pile. It concerns construction methods.

[Prior Art] In the conventional art of this type, a sheet pile is generally driven into the ground by a vibration method. When the sheet pile is driven into the ground by the vibration method, it receives the reaction force from the ground along with the vibration applied to it, and the edge of the sheet pile suffers damage and deformation such as cracks and bending, as well as deformation due to buckling. . Since the sheet pile has a thin plate shape, when it is driven into hard ground, it bends easily, and at the end it becomes impossible to drive.

As a method of coping with this problem, a power-up means of a vibro hammer is generally adopted, and noise and vibration are also increased accordingly, which has been a serious pollution problem.

The inventor of the present application has already made related proposals for a construction method capable of easily excavating the ground with relatively low noise and low vibration for the purpose of solving the above problems, and an excavation pipe used for the construction method. If the method and the drill pipe are applied, a certain degree of effect can be obtained in the sheet pile driving.

The first is that a pilot pipe having a diameter smaller than that of the drill pipe is projected downward from the central portion of a steel hollow drill pipe having a sharp tooth projecting at the tip thereof, and the pilot pipe has a diameter smaller than that of the base end. A nozzle for high-pressure water injection in the hollow part of the pilot pipe by a construction method in which a slack of the ground is created on the outer peripheral side of the pilot pipe by using a drill pipe provided with a tip blade formed of a thick steel pipe. The water injection pipe is housed, and the jet pressurization of high-pressure water reduces the ground press-fitting resistance of the tip of the excavation pipe to achieve low vibration, low noise, and labor saving (see Japanese Utility Model Publication No. 63-65794). .

The second method is to use a hollow steel-made drill pipe with a sharp tooth projecting downward on the inner peripheral surface of the tip, and vibrate the drill pipe with a vibrohammer to propel it into the ground to deposit earth and sand in the pipe. When it is filled with, it is pulled out to leave a hole in the mark, which is low vibration, low noise,
This is for labor saving (see Japanese Patent Laid-Open No. 59-213891).

Part 3 is to open a water hole at an appropriate position in a hollow steel drilling pipe with a sharp tooth projecting at the tip, and use the water pipe to eject high-pressure water from the tip while By promoting it, burying it in the ground, filling the pipe with earth and sand, and pulling it out, leaving a hole in the trace, it is possible to respond to gravel, mudstone, etc., but low vibration, low noise, This is for labor saving (see Japanese Patent Laid-Open No. 60-43517).

A conventional technique is to excavate the ground and drive a sheet pile into a loose excavation hole by the excavation pipe and a construction method using the excavation pipe.

[Problems to be Solved by the Invention] The above three types of ground excavation methods have their advantages and disadvantages. That is, in the example of the conventional technique No. 1,
Since it is possible to reduce the ground press-fit resistance on both the inner and outer wall surfaces of the excavation pipe and the tip surface, it is suitable for excavating a large-diameter hole at a time by adapting to the ground condition of soft rock and hard rock. When the ground is a soil that is easy to tighten, such as fine sand, when the sheet pile is placed in the hole where the excavation pipe has been pulled out, the placement volume may be insufficient due to insufficient excluded volume or the placement vibration may cause the soil to become unloaded. There was a problem that it would be possible.

In the example of the conventional technique No. 2, the earth pressure is eliminated on the inner and outer wall surfaces of the excavation pipe, and the ground press-fit resistance is reduced. Therefore, it is suitable for excavating the ground in a narrow space and eliminating the sediment, but Hard ground with an N value (a resistance value attached to the tip of round steel is press-fitted into the ground to estimate the resistance of the stratum and the strength of the stratum is displayed from that value) exceeds 50 because the tip surface press-fit resistance is large. There was a problem that it was not possible to excavate, and therefore it was not possible to place a sheet pile.

In the example of the related art No. 3, since the high-pressure water injection structure is added to the excavation pipe in the example of the second example, and the excavation is performed while the high-pressure water is ejected from the tip of the excavation pipe, the N value close to that of hard rock is obtained. It is possible to excavate the ground exceeding 50, but there is a problem that it is difficult to construct a sufficient excluded volume by placing a sheet pile on the excavation mark by this construction method alone.

Here, an object of the present invention is to provide a sheet pile driving construction method capable of solving the problems of the conventional construction methods for driving the above-mentioned sheet piles, in view of the problems.

[Means for Solving the Problems] That is, the object of the present invention is to provide a sharp tooth at the tip and a high pressure water from the tip of an excavation pipe provided with a pilot pipe at the center of the tip while preliminarily digging the ground. The first step of driving the excavation pipe at the sheet pile driving position, and the excavation pipe having a sharp tooth at the tip of the excavation pipe is removed and inserted into the pipe to remove the excavation pipe from another location. And a second step of creating an excluded volume in the ground, and an excavation tube in which high-pressure water injection is added to the excavation tube of the second step after the excavation tube is pulled out in the second step, This is achieved by a sheet pile driving construction method, which comprises a third step of tying together sheet piles and pulling out only the excavation pipe.

[Operation] According to the method for constructing a sheet pile by the above steps, if the ground has a hard portion and it is impossible to place the sheet pile alone, the hard ground is excavated in the first step. Can be loosened. In addition, when the ground has a fine sand portion and it is extremely easy to tighten and it is difficult to build a large excluded volume in the trace excavated in the first step, the excluded volume can be secured by the second step. Furthermore, by using the third step of tying up the sheet pile and the excavation pipe and driving it into the ground, which is completely different from the conventional method, by using the ground in any state,
It is possible to drive the sheet pile easily.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram for detailing the steps applied to this construction method. In the first step, as the excavation pipe 1, a first excavation pipe 1A equipped with a pilot pipe and a high-pressure water jet nozzle is placed in the ground. In the second step, as the excavation pipe 1, a second excavation pipe 1B having a tooth at its tip is driven. In the third step, as a drill pipe, a third drill pipe 1C in which a high-pressure water jet pipe is added to the second drill pipe
Using the above, the third excavation pipe 1C and the sheet pile are tied together and driven into the ground, and the third excavation pipe 1C is pulled out to complete the construction, but those constructions are performed in the state shown in FIG. .

That is, in the sheet pile driving work according to the present invention,
First, the ground G on which the sheet pile is to be driven is first shallowly excavated by a power shovel or the like, and an excavation ruler 6 that vertically supports the excavation pipe 1 is installed. Then, the end grip 5 provided at the upper end of the excavation pipe 1 is grasped by the vibro pile hammer 3 suspended by the crane 7, the excavation pipe 1 is erected vertically on the ground G, and in this state, the vibration is applied to the excavation pipe 1. While giving
Propel it in the ground. The first to third drill pipes are all steel pipes, and the end grips are made of H steel or the like.
Formed by welding. Crane 7 is used to insert and remove the drill pipe 1.
The vibro hammer 3 is lifted by the hook 9 of the crane 7, and the end grip 5 of the drill pipe 1
Are gripped by the chuck mechanism 8 of the vibro hammer 3.

Here, the first step of the present invention will be described with reference to the process explanatory diagrams of FIG. 1 and FIG. Fig. 2 (a)
Is an explanatory view of the first step, and (b) is a partially cutaway side view showing the first excavation pipe 1A. In the figure, the one-dot chain line shows the sheet pile 10 to be placed. The pilot pipe 2 having a diameter smaller than that of the main pipe is arranged on the central axis on the tip side of the excavation pipe 1A, and the tip blade 11 of the pilot pipe 2 is projected further ahead of the tip of the main pipe. The tip of the main pipe and the tip of the pilot pipe 2 have sharp teeth. The pilot pipe 2 is hollow and has a water supply pipe 12 for jetting high-pressure water and a jet nozzle 13 inside the tip. The excavation pipe 1A is vibrated by the vibro hammer 3 and propelled to the ground positions G1 and G2 shown in FIG. 2 (a) while injecting high-pressure water, where it is propelled to a certain depth. By pulling out from the pipe, the sand and sand clogged in the pipe 1A can be removed and a hole can be left in the ground. The excavation pipes should be inserted and removed as necessary. According to the first step, the drill pipe 1A
It is possible to reduce the press-fitting resistance, and in combination with the earth pressure eliminating action of the excavation pipe 1A, it is possible to easily excavate holes not only on soft ground but also on hard ground.

However, after performing the first step, the drill pipe 1
In some cases, even if the sheet pile 10 is to be placed as it is after the A is pulled out, it is impossible. For example, there is a case where the ground has a fine sand layer portion, and even if it is stirred with high-pressure water, it is quickly tightened. Even if the excluded volume is built in the ground, when the next sheet pile driving is started, the ground is tightened by the vibration of the driving and the driving becomes impossible.

In the above case, the second step creates a large excluded volume in the ground to facilitate the placement of the sheet pile. The second step will be described with reference to FIGS. 3 (a) and 3 (b). Third
Drawing (a) is a process explanatory view and (b) is a side view of excavation pipe 1B used for the 2nd process. Since the protruding tooth 4 is provided at the tip of the excavation pipe 1B, it can be easily driven into the fine sand ground. In the first step shown in FIG. 3, the excavation pipe 1B is driven into the traces G1 and G2 that have been extracted from the excavation pipe 1A while vibrating with the vibro hammer 3. When the excavation pipe 1B has been driven to a certain depth, the pipe 1B is once pulled out from the ground by the crane 7 so as not to give vibration as much as possible. At this time, the excavation pipe 1B is withdrawn while the pipe is filled with sand, and the traces G1 and G2 of the excavation pipe 1B withdrawn.
There is a hole in it. In this second step, since water is not used, the fine sand that has been broken and loosened in the first step and the like can be easily filled in the same pipe 1B and removed to another place. That is, the excavation traces G1 and G2 are constructed with an exclusion volume sufficient to drive the sheet pile.

Next is the third step of driving the sheet pile into the excavation marks G1 and G2 built in the second step. When it is necessary to drive a large sheet pile with a length of 25 m or more and a width of 50 cm or more due to the construction work, conventional water is used even if the driving ground is loosened in advance and a certain amount of excluded volume is secured. In the jet vibro method, when the soil is fine sand, the particles are very small and the specific gravity is large, so
The agitated sand is re-tightened or the water pressure is absorbed in the jetted high-pressure water, and it is difficult to cut the edge between the sheet pile and the sand, and it remains difficult to drive due to deformation or damage.

Therefore, in the third step, the sheet pile 10 and the excavation pipe 1C are tied together and driven. 4A is a process explanatory view, FIG. 4B is a perspective view of the state, and FIG. 4C is a side view of the excavation pipe 1C used in the third process. Also in this case, description will be given by using FIG. 1 and FIG. 4 together. In the figure, first, the crane 7 is used to hang the sheet pile 10 at a position shown in the figure, and then the vibrating pile hammer 3 is used to drive the sheet pile 10 to a position where the sheet pile 10 can be easily driven to be self-supporting. The driving depth should be approximately 1/2 to 3/4 of the total length of the sheet pile, and the temporary driving should be performed gently.

Next, while excavating the excavation pipe 1C with the vibro pile hammer 3, the excavation pipe 1C is driven into the position of the ground G3 so as to be attached to the sheet pile 10 that has been provisionally hammered. Then, the sheet pile 10 and the excavation pipe 1C are integrated by fixing them with the sheet pile bands at two portions of the driving ruler 6 above 50 to 150 cm. The fixed position will be appropriate according to the construction conditions.

The excavation pipe 1C is provided with an end grip 5 which can be grasped by the vibropile hammer 3 similarly to the excavation pipes used in the first and second steps. or,
A sharp tooth 4 is provided at the lower end, and a high pressure pipe 14 for injecting high pressure water is provided at the side end.

The excavation pipe 1C integrated with the above-mentioned sheet pile 10 is further driven by the vibro pile hammer 3 until the upper surfaces of both heads substantially coincide with each other. The upper end of the end grip 5 is welded with a pair of protrusions 15 that hold the upper end of the seat pile 10 from above, and the protrusion 15 of the excavation pipe 1C presses the upper end of the seat pile 10 so that both The driving is temporarily stopped when the upper ends substantially coincide with each other.

Here, the chuck mechanism 8 is temporarily opened, the excavation pipe 1C is released, and the sheet pile 10 and the excavation pipe 1C are chucked together. Integrated sheet pile 10 and drill pipe 1C
The end grip 5 with the vibro pile hammer 3.
Apply vibration to and drive to the specified depth. High pressure pipe 14
Discharges high-pressure water with a discharge rate that corresponds to the soil quality, facilitating soil removal. Further, if necessary during the process, a work of sucking earth and sand together with water by the vacuum device 16 is added.
When the sheet pile 10 is driven into a predetermined position to a predetermined depth, the chuck of the chuck mechanism 8 is released, the next sheet pile is hung at the next driven ground position G4, and is made to stand by itself. It will be pulled out and moved to the next placement. The excavation pipe 1C is pulled out while vibrating gently with the vibro pile hammer 3 until it is separated from the sheet pile 10. Pull out while giving the minimum required vibration.
At this time, since the lower part of the projection 15 provided on the end grip 5 of the tube 1C is open, the sheet pile 10 remains driven in the driving position.

By successively performing the above-mentioned first to third driving steps, it is possible to easily drive the sheet pile into the ground including the fine sand layer, which could not be driven alone in any of the steps. Becomes By the way, FIG. 5 shows a columnar view of the ground on which the inventor of the present invention has made a trial sheet pile driving by the driving method of the present invention and the result of the penetration test corresponding to the N value of 6
It is shown up to 0. This ground is about 5m deep
15m is medium sand, 15m to 20m is fine sand, etc.
Gravel containing large stones, fine sand with small stones, loam layer, etc. are mixed. After the depth of 22 m where the soil becomes gravel,
It takes 50 times each to drive 7 to 11 cm, and it is estimated from this that the N value in the penetration test is obviously around 150. The above-mentioned ground column diagram is an example of the soil quality that the present inventor has carried out sheet pile construction as national repair work.

In the ground shown in FIG. 5, the sand particles are extremely small, and the fine sand portion having a large specific gravity and the sand and gravel portion are mixed, and a sheet pile having a length of 25 m and a width of 50 cm which is necessary for construction is used alone. It was impossible to drive. Not only that, even after a certain amount of excluded volume was built by using the above-mentioned first, second, and third steps alone, it was impossible to drive the sheet pile alone. This is considered to be because when the sheet pile was driven in, even if the fine sand was stirred with high-pressure water or the like, it quickly tightened and the frictional resistance could not be reduced. An actual example of using the construction method of the present invention for the above construction shows that the sheet pile has a length of 25 m as described above,
The width of the excavation pipe 1A used in the first step is 50 cm and the diameter is 2
70φ, the diameter of the excavation pipe 1B used in the second step is 270
φ, the diameter of the excavation pipe 1C used in the third step is 270φ
Then, using one Nipira 60ps vibropile hammer and one 150kg / cm ₂ jet pump,
The sheet pile could be easily driven up to a depth of 25 m. A conventional method is used for the first and second steps, but this method is easy to construct and has low vibration and low noise as described in the conventional example.

The third step conforms to this and has extremely low vibration. As an example, in FIGS. 6 and 7, FIG. 8 and FIG.
The conventional jet vibro method and the vibration test result when the inventor of the present invention drives a sheet pile in the third step of the present invention are shown. It is the data transcribed from the chart which recorded the vibration level using the OV-25B pollution vibrometer manufactured by Acoustic Instruments Co., Ltd. The sheet pile used was a VL type having a length of 25 m, and the driving conditions were almost the same. However, one jet pump used in the present invention is 150 kg / cm ₂ ,
In the conventional example, there were two units of the same type. Ground depth 20-25m
It is a measurement result in the vicinity.

FIG. 6 shows the vibration level in the conventional jet vibro method. The vibration continued at a high level of about 78db, but could not be placed. As the sheet pile placing ground, a soil having a soil structure similar to the ground subjected to the national repair work described below was selected, and the measurement was performed at a position 10 m away from the placing position.

FIG. 7 is a vibration level measurement result when sheet pile driving is performed according to the third step of the present invention under the same conditions as in FIG. 6 under the same conditions. The vibration level was about 60 db, and the implant was possible.

FIG. 8 and FIG. 9 show the vibration level when the above-mentioned national auxiliary work is carried out. The conditions for placing the sheet pile are the same as those shown in FIGS. Figure 8 shows 10 points from the placement point.
The result of measurement at a distance of m, Fig. 9 shows 10
It is a measurement result in the symmetrical point of the said measurement point which was m distance.
It is possible to drive with a value much smaller than the reference value 75db specified by the Vibration Regulation Law. However, what is different from the first and second steps is that the excavation pipe is attached to the sheet pile, which is not in the past, and the upper end portions are aligned and driven. Since the earth and sand are excavated at the tip of the excavation pipe, and the sand is blown up from the discharge port at the upper end of the excavation pipe, the sheet pile is placed,
Sediment around the excavation pipe and around the sheet pile gradually moves to facilitate placing. In this case, it is more effective to use well vacuum to forcefully discharge the sand.

This is because in the first step, including the gravel layer of the ground and the pebble-mixed sand layer, the ground pressure is easily loosened using the earth pressure elimination method, and in the second step a large excluded volume is built, In the next third step, the piles of the piles of the excavation pipe were struck together, and when the excavation pipe was driven into the ground, the inner and outer edges of the sand were cut at a certain area and destroyed by the tooth. Sand easily blows up the inside of the pipe due to water pressure and is discharged to the outside of the pipe from the discharge port provided at the upper end of the pipe, and the sand around the sheet pile moves toward the tip of the pipe, It is considered that the frictional resistance decreases. By pulling out the sand filled in the pipe to the ground surface and discharging it to another place, a larger excluded volume is generated in the placing ground,
It affects one after another, easily escapes large stones, etc., and the driving time of the sheet pile is shortened.

[Effects of the Invention] As can be seen from the above description, according to the construction method of the present invention, it is easy to consolidate the sheet pile with fine sand, which is conventionally impossible to drive, or a complicated ground including a gravel layer. Also, in the deep ground, it is possible to drive the seat pile by using relatively simple equipment such as a vibro pile hammer and a jet pump.

[Brief description of drawings]

FIG. 1 is a process explanatory diagram of the present invention, and FIGS. 2 (a) and 2 (b).
Is an explanatory view of the first step of the present invention and a side view of the drill pipe used, FIGS. 3 (a) and (b) are explanatory views of the second step and a side view of the drill pipe used, FIG. (A), (b) and (c) are explanatory views of the third step, a perspective view thereof and a side view of a drill pipe used, and FIG. 5 is a test pile driven by a construction method of the present invention. A column diagram showing the ground structure and a chart showing the results of the penetration test, FIGS. 6 and 7, FIG. 8 and FIG. 9 are diagrams showing the vibration test results of the conventional jet pile construction method and this embodiment. 1, 1A, 1B, 1C ... Drilling pipe, 2 ... Pilot pipe, 3 ... Vibro pile hammer, 4 ... Tooth, 5
…… End grip, 6 …… Excavation ruler, 7 …… Crane, 10 …… Seat pile

Claims (1)

[Claims] 1. In a sheet pile driving work, a sharp tooth is provided at the tip and high pressure water is jetted from the tip of an excavation pipe provided with a pilot pipe at the center of the tip, and the excavation is carried out in advance at the seat pile driving position of the ground. The first step of placing a pipe and the excavation pipe with a sharp tooth attached to the tip of the excavated pipe to remove the sand and sand that has entered the pipe to another place, and remove the volume to the ground. And a second step of making a digging pipe in the second step, a digging pipe in which high-pressure water is added to the digging pipe of the second step, and a sheet pile are laid together. A sheet pile driving construction method comprising a third step of extracting only the excavation pipe.