JPH02183012A - Method for driving pile to hard sandy ground - Google Patents

Abstract

PURPOSE:To increase resistivity against drawing-out with increased thrusting force by uniting a pile, driven in to a prescribed depth by a combined method using a vibro pile driver and jetting water ejected from a water-convying pipe, with the ground around the driven-in pile. CONSTITUTION:A batter pile 2 is driven into a hard sandy ground 1 up to a prescribed depth by a combined method using a vibro pile driver equipped with a vibro hammer 3 that is installed to a batter-pile-driving leader 12 and jetting water ejected from a nozzle at the tip of a water-conveying pipe 5. When the jetting water from the water-conveying pipe 5 is replaced with high- pressure cement milk M and only the water conveying pipe 5 is drawn out while the cement milk is injected. Then the cement milk M is mixed with sandy soil that is disarranged by injection of the jetting water around the batter pile 2, and soil cement body 13 is formed thereby around the batter pile 2. Thereby the batter pile 2 and the soil cement 13 are united together, increasing resistivity against drawing-out.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for driving piles into hard sandy ground using a combination of a vibrating pile driver and a water jet. This article relates to a pile driving method for hard sandy ground that integrates these two methods.

[Conventional technology]

Conventionally, when driving piles into hard sandy ground, a vibrating pile driver such as a vibrohammer and a water jet were used in combination.
A method of driving piles while loosening the ground is used, but in this case, the ground around the pile is disturbed by the vibrations of the pile driver and the water jet, reducing the strength of the ground and weakening the surrounding area of the pile. There is a problem that the frictional resistance between the surface and the ground decreases, so if the driven pile is subjected to pushing force, the supporting force at the tip of the pile can be expected, so this supporting force may be able to resist it. However, when a driven pile is subjected to a pull-out force, the only pull-out resistance is the frictional resistance between the surrounding surface of the pile and the ground, resulting in insufficient pull-out resistance.

Conventionally, a method of grout injection has been considered, but in grout injection, the pressure at which the grout is discharged into the ground is as low as several kg/ctA, and the grout is simply placed in the gap between the surrounding surface of the pile and the ground. However, the problem is that the frictional resistance between the grout and the surrounding surface of the pile only increases, and the ground around the pile remains disturbed, so a significant increase in pullout resistance cannot be expected.

[Problem to be solved by the invention]

The present invention was made in order to solve the above-mentioned conventional problems, and it integrates the pile driven using a vibrating pile driver and a water jet in combination with the ground around the pile, and reduces the pushing force. The object of the present invention is to provide a pile driving method that not only increases the pull-out resistance but also increases the pull-out resistance.

[Means for Solving the Problems] As a means for solving the above problems, the pile driving method of the present invention uses a vibrating pile driver such as a vibrohammer and a water jet jet from a nozzle at the tip of a water conduit. After driving the pile to a specified depth in the hard sandy ground, the water pipe is switched to a water jet and a high-pressure cement hardening agent such as cement milk is spouted out, and only the water pipe is pulled out. This is characterized by the fact that the sandy ground disturbed by the water jet around the pile is mixed with a cement-based hardening material and hardened, thereby integrating the pile and the surrounding ground of the pile.

[Example] An example of pile driving work using the method of the present invention will be described below with reference to the drawings. Figure 1 shows an example of driving a diagonal pile 2 such as a steel pipe into hard sandy ground I using the method of the present invention. It is an explanatory diagram of an example of pile driving work to be carried out, and for hard sandy ground 1,
A vibrohammer 3 which is a vibrating pile driver attached to a diagonal pile driving leader 12 suspended by a crawler crane 11 and high pressure water W from a water jet supply device 4 are supplied to a high pressure hose 15 and a nozzle at the tip of a water conduit pipe 5. The slanted pile 2 is driven to a predetermined depth in the hard sandy ground 1 by using a jet of water ejected from the tip of the slanted pile 2 through the slanted pile 2.

When the diagonal pile 2 is driven by the vibrohammer 3 and the water jet ejected from the water pipe 5, a void 6 is generated in the hard sandy ground l on the outer peripheral surface of the diagonal pile 2, as shown in Fig. 3. , a region of reduced ground strength 7 will be formed around it.

Therefore, in the present invention, the water conduit pipe 5 that was spouting the high-pressure water W is
By switching the connection with the high pressure hose 15 of , to the high pressure hose 9 of cement milk M, which is a high pressure cement hardening material fed from the cement milk supply plant 8,
Cement milk M is spouted from a nozzle at the tip of the same water conduit 5.

If necessary, drive another diagonal pile 2 into the hard sandy ground 1 in this state, and after completing the driving, remove the vibrohammer 3 and the water pipe 5 from the diagonal pile 2, and remove the diagonal pile 2 from the water pipe 5. Only the water pipe 5 is pulled out while spouting the cement milk M.

As mentioned above, the cement milk M is spouted from the water conduit 5 onto the ground at a pressure of about 10 kg/c.
Cement milk M and earth and sand particles are ejected into the disturbed hard sandy ground 1 around the slanted pile 2 under high pressure of ~10 kg/ant, or even 200 kg/C11N if necessary. After stirring and mixing and after a predetermined period of time, the gap 6 between the outer circumferential surface of the slanted pile 2 and the hard sandy ground 1 shown in FIG.
is filled with solidified cement milk or soil cement body 10 shown in FIG. become unified.

Note that if the switching operation between the high-pressure hose 15 for the high-pressure water W and the high-pressure hose 9 for the cement milk M as described above is not done quickly, the nozzle at the tip of the water conduit 5 will become clogged, and the cement milk M may not be spouted out. Therefore, it is advisable to provide an appropriate switching device between high-pressure water W and cement milk M, such as a one-touch coupler, which can quickly perform this switching.

In the above embodiment, the case where the diagonal pile 2 is driven has been explained. In this case, when the diagonal pile 2 is driven using the vibro hammer 3 and the water jet jet by high pressure water W, as shown in FIG. Since the hard sandy ground 1 on the upper side of the diagonal pile 2 indicated by the arrow In addition, two injection pipes 14 having lateral injection nozzles 16 shown in the cross-sectional view of FIG. 5 are disposed on the upper surface side indicated by the arrow It is effective to pull out the cement milk M while spouting it onto the ground on the upper surface side of the inclined pile 2.

In this case, in order to prevent the lateral injection nozzle 16 from clogging when driving the oblique pile 2, the cement milk M is always discharged at a low pressure.

In addition, although the case of the oblique pile 2 was explained in the said Example, it can apply similarly to the case of a vertical pile, and in this case, the said injection pipe 14 is not necessary.

[Effects of the Invention] As explained above, according to the construction method of the present invention, a cement-based hardening material such as cement milk is spouted at high pressure into the ground around the pile through the water pipe, and the water pipe is moved upward along the pile. As the pile is pulled out, the cement milk and soil particles are stirred, a soil cement body is formed around the pile, and the pile and the fill cement body become one, which has the effect of increasing the pulling resistance.

Additionally, the water jet conduit and nozzle used for driving piles can also be used to discharge cement milk, which has the effect of reducing penetration resistance during pile driving and requiring simple equipment.

[Brief explanation of the drawing]

Fig. 1 is an explanatory view of an example of driving a diagonal pile using the construction method of the present invention, Fig. 2 is an enlarged plan cross-sectional view of the steel pipe diagonal pile shown in Fig. 1, and Fig. Figure 1 is a side sectional view showing the state of the ground upon completion of driving the slanted pile, Figure 4 is a side sectional view showing the state of the ground after cement milk has spouted onto the outer circumferential surface of the slanted pile in Figure 3, and Figure 5. 3 is an enlarged side cross-sectional view of a lateral injection nozzle provided at the tip of the injection tube of FIG. 2; FIG. 1... Hard sandy ground, 2... Oblique pile, 3... Vibrohammer, 5... Water pipe, M... Cement milk, W... High pressure water. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] After driving a pile to a predetermined depth in hard sandy ground using a combination of a vibrating pile driver and a water jet from a water pipe, a high-pressure cement-based hardening material is ejected from the water pipe while only the water pipe itself is driven. A pile driving method for hard sandy ground that involves pulling out.