JPS6043517A - Coffering work and tubular pile therefor - Google Patents

Abstract

PURPOSE:To facilitate coffering work by draining water from deep strata by a method in which a water pipe is provided near the lower end of a steel tubular pile, sheathing using the steel tubular pile is made in the ground for coffering, and water is pumped up from the bottom of the pile. CONSTITUTION:A water hole 9 is provided near the lower end of a steel tubular pile 1, and a coupler 6 is provided in the longitudinal direction of the periphery of the pile 1. The steel tubular piles 1 are connectedly driven in such a way as to surround the working area (a). A drain hose 10 having a net on its tip is inserted into the pile 1, and water coming into the pile 1 is pumped up by a pump, etc. Water can thus be drained from deep places of the ground of working area, and therefore, coffering work can be made easier.

Description

[Detailed Description of the Invention] This invention prevents the collapse of the ground when excavating the ground for foundation work, etc.
This invention relates to a method of cofferdam construction (so-called pile stoppage) to prevent water from entering the work area, and the tubular piles used for this method.

BACKGROUND OF THE INVENTION Conventionally, cofferdam work, such as when constructing a structure such as a bridge pier underwater, has been carried out mainly by surrounding the work area with sheet piles. This sheet pile is usually press-fitted into the ground by the impact method, but the problems in this case are the deformation and damage of the sheet pile and the accompanying difficulty in driving it.

In other words, when a sheet pile is driven into the ground by the impact method, in addition to the impact applied, it receives a reaction force from the ground, which causes damage and deformation such as cracks and bending to the end of the sheet pile, as well as buckling. susceptible to deformation due to Now, assuming that the length of the sheet pile is l, the Young's modulus is E, and the moment of inertia of area is I, -buckling load P is as follows.

P=n2 π2 EI/I22 (however, n=1.2.3...-) As is clear from this equation, long piles and piles with low stiffness (EI) are relatively susceptible to buckling, and sheet piles are especially susceptible to buckling. Since it is a thin plate-like material, the moment of inertia l-1 of the cross section is small, and it will easily bend if a strong impact is applied to it on hard ground. For these reasons, it has been considered impossible to drive long sheet piles into the ground where the N value exceeds 50 in a penetration test.

In addition, one of the problems with this cofferdam construction is the problem of drainage of spring water, etc. in the work area.

Not only in the case of water-temperature foundations and submerged foundations, but also in normal above-ground construction, spring water such as groundwater may occur as the excavation is dug, so it is necessary to drain this water to the outside of the work area. Traditionally, drainage during cofferdam construction was
A method has been adopted in which a shallow water reservoir called a funeral hall is installed in the corner of the bottom of the root digging, and water is led into this and drained using a pump.

However, with this drainage method, only the water at the bottom of the excavation can be drained, and furthermore, the water in the lower layer cannot be drained. For this reason, the earth and sand to be excavated always contains water, making excavation difficult.

This invention was made in order to solve the above-mentioned problems in conventional cofferdam construction, and it is possible to easily drive piles and carry out cofferdam work even in hard ground, and to significantly reduce groundwater etc. contained in the ground. The purpose is to enable drainage from deep places, thereby making it easier to carry out root digging work, etc. EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention will be described in detail based on the illustrated embodiment.

In the cofferdam construction according to the present invention, a pipe pile 1 as shown in FIG. 1A is used instead of a sheet pile. As shown in Fig. 3, this pipe pile 1 has a rust-resistant end grip 3 attached to the upper end of the steel pipe 2 by welding or the like so that it can be gripped by a vibropile hammer 4, and a sharp propelling blade is attached to the lower end. A large number of 5.5-- are provided protrudingly.

These propulsion blades 5, 5, etc. may be formed of the same material as the intermediate pipe 2, for example by notching the tip of the steel pipe 2, but
If the ground is particularly hard, the surface of the blade may be coated with a hard material, or a carbide tip made of a different material from the steel pipe 2 may be welded to the tip of the intermediate pipe 2 to form the propelling blades 5, 5, etc. You can also do that.

Joints 6, 6 are provided on the longitudinal side of the steel pipe 2 to connect adjacent pipe piles 1, 1- to each other when the pipe is driven into the ground. This joint 6.6 is preferably one that is easy to fit in, difficult to come off during driving, and has a high water-stopping property. As shown in FIG. 4, adjacent pipe piles 1.1 are connected in a watertight manner by fitting the tips into each other.

Further, as will be described later, for the pipe pile 1 for draining water from the ground, water holes 9.9 are opened at appropriate positions in the steel pipe 2.

When the pipe pile 1 is driven into the ground, it is usually driven into the ground while being vibrated by a vibropile hammer 4, as shown in FIG.

That is, first, the end grip 3 is gripped by the vibro pile hammer 4 suspended from the crane 7, and the pipe pile 1 is vertically erected on the ground, and in this state, the pile 1 is propelled into the ground while being vibrated.

When the driven pipe pile 1 is to be pulled out of the ground, the end grip 3 is gripped by the vibropile hammer 4, and in this state, it is pulled upward by the crane 7 while giving a slight vibration. Since the pipe pile 1 pulled out in this way is filled with earth and sand, it is possible to remove the earth and sand by applying a strong vibration to the pipe pile 1 that is suspended by the crane 7. can.

When driving the pipe pile 1 as described above, if the propulsion resistance from the ground is particularly strong and it is difficult to drive the pipe pile 1, once the pipe pile 1 is driven to the point where it can be driven,
After the pipe pile 1 is pulled out and the earth is removed from it, the pipe pile 1 can be easily propelled by inserting the pipe pile 1 into the same place again and driving it further. Normally, by repeating these operations two or three times, it is possible to drive the pipe pile 1 deep into any hard ground.

In addition, when removing soil, if the ground contains a hard consolidated layer such as consolidated silt, the soil that has entered the pipe may become hard and compacted, making it impossible to remove the soil from inside the pipe pile 1. . Therefore, when driving into this type of ground, it is best to detachably attach blades 8, 8 in the radial direction on the lower end side of the steel pipe 2. In the case shown in the figure, two blades 8 with sharp cutting edges on the top and bottom
．． 8 are inserted and attached to the lower end of the steel pipe 2 so as to be perpendicular to each other. When the pipe pile 1 is driven in this way, when the earth and sand in the consolidated layer enters the steel pipe 2 as the pile l is propelled, the blades 8.8 break the earth and sand into small pieces. For this reason,
After pulling out the pipe pile 1, by pulling out the blades 8, 8 from the steel pipe 2, the earth and sand therein can be easily removed from the lower end of the steel pipe 2.

By driving the pipe pile 1 into the ground in this manner, it has become possible to drive long piles into hard ground, which was difficult to do with conventional sheet piles. Incidentally, the 6th
The figure shows a columnar diagram of the ground into which the inventor of the present invention has experimentally driven the ground, and the corresponding results of the penetration test up to an N value of 50. This ground has an N value of over 50 in some parts up to 20m deep, and is 22m long.

Pipe pile 1 with a diameter of 300 mm could be easily driven with a 60 ps vibro pile hammer manufactured by Nippeisha. In addition,
At this time, the driving time per piece is approximately 15-16
It was a minute.

To carry out cofferdam work using this pipe pile 1, please refer to Figures 2 and 4.
As shown in the figures and FIG. 5, pipe piles 1 are driven around a certain work area a where so-called root digging is to be performed, while being joined by joints 6.6, to surround the area a.

After surrounding the work area a in this way, the water holes 9, 9
- Remove the earth and sand from some or all of the pipe piles 1, and pump up the water that has entered the pipe piles 1 from the ground.
Spring water from the ground.

Drain water leakage, etc.

To remove the earth and sand inside the pipe pile 1, for example, use a steel pipe that is thinner than the inner diameter of the pipe pile 1, drive it into the pipe pile 1, and then gently pull it out. Sediment can be taken out to the outside. The earth and sand packed in the steel pipe can be removed from the steel pipe by lowering the pipe with a crane 7 and applying strong vibrations with a vibro pile hammer 4.

In the pipe pile 1 from which the earth and sand have been removed, the water passage hole 9.9-.
Since water from the surrounding ground will infiltrate from the hose, as shown in Figure 5, a hose 10.10 with a net etc. attached to the tip is used.
-... can be inserted into the same pipe pile 1 to collect them into one pipe, and the water can be drained by pumping the water using a pump or a vacuum well method. By draining the ground in the work area a in this manner, water contained in the ground can be removed to a considerable depth. Therefore, when performing so-called root digging, there is no generation of spring water, and the ground can always be maintained in a water-free state. Therefore, there is no need to provide a so-called funeral hall at the bottom of the excavation for drainage.

As described above, according to the present invention, it is possible to perform deep cofferdam work on hard ground, which was difficult with conventional sheet piles, and at the same time, it is possible to drain water to a considerable depth in the ground, so-called This will make it easier to dig roots. In particular, it will shorten the pile driving time and also allow the use of relatively simple equipment such as a vibro-pile hammer to mark deep areas, which will shorten the construction period and reduce the number of man-hours. becomes possible.

[Brief explanation of the drawing]

Fig. 1A is a perspective view of an embodiment of the pipe pile according to the present invention with the middle part omitted; FIG. 3 is a plan view of the deadline state showing an example of the above, and FIG.
FIG. 4 is a plan view showing the connected state of the pipe piles, FIG. 5 is a sectional view taken along the line 1-A in FIG. 2, and FIG. These are a log diagram showing the structure and a chart showing the results of penetration tests on the same ground. 1-Pipe pile 2-Steel pipe 3-End grip 4-Vibro pile hammer 5-Propulsion blade 6-Joint 8-Blade a.1 Working area Patent applicant Kyohi Heavy Equipment Co., Ltd. People Patent Attorney Kazuyoshi Hojo

Claims (1)

[Claims] 1. Driving pipe piles with joints in the side longitudinal direction while connecting them, surrounding the work area, extracting earth and sand from part or all of the pipe piles, and inserting the pipes from the ground. A cofferdam construction method characterized in that infiltrated water is pumped up and drained from the ground in the work area. 2. An end grip is provided at one end of the steel pipe that can be gripped by a bi-robile hammer, and a sharp propelling blade is provided protruding from the lower end of the end grip to connect adjacent pipes to each other along the longitudinal direction of the side surface of the steel pipe. A pipe pile characterized by being provided with a joint that 3. The pipe pile according to claim 2, wherein a blade is detachably attached to the tip end of the steel pipe in the radial direction of the pipe.