JP2807699B2 - How to prevent corrosion of cast-in-place steel piles. - Google Patents

Description

The present invention relates to a method of preventing corrosion of cast-in-place steel piles.

(B) Conventional technology Conventionally, a hammer driving method, a vibro driving method, a middle dig driving method, and the like have been adopted for driving a steel pile.

These steel piles are expected to have a corrosion allowance of about 2-3 mm.

(C) Problems to be Solved by the Invention However, in addition to the harmful effects of noise and vibration, the above-mentioned hammer driving method involves corrosion-resistant treatment of the steel pile to rub the inner and outer surfaces of the steel pile with the ground. Also, there is a disadvantage that the inner and outer surfaces are damaged, the metal is exposed, and it is easily corroded in the soil.

The vibro casting method is also reduced in noise and vibration as compared with the above method, but has the same problem that the ground rubs the inner and outer surfaces of the steel pile, and has a disadvantage that it is easily corroded in the soil.

In the excavation method, noise and vibration are generated by the gravel and boulders in the ground, and the ground cannot be relaxed by mixing liquid material into the excavated soil to discharge the soil from the borehole. Due to the torque, a large-diameter excavation hole cannot be drilled, which has the disadvantage that the outer diameter of the steel pile that can be driven is limited.

Further, it is necessary to treat the earth removal, and since the number of dumping sites has been reduced in recent years, it has become difficult to perform the earth removal processing.

Further, the friction with the ground is reduced as compared with the above, but in the case of corrosive ground, for example, in the case of acidic ground, it was not possible to avoid corrosion.

(D) Means for Solving the Problems According to the present invention, the excavated soil in the excavation hole drilled in the ground of the casting site is mixed with the granular aggregate and the alkaline solidifying agent,
It is an object of the present invention to provide a method for preventing corrosion of cast-in-place steel piles, which comprises inserting a steel pile into a borehole before solidification of the mixture.

(E) Action / Effect According to the present invention, the mixture in the excavation hole is a mixture of excavated soil, granular aggregate, and an alkaline solidifying agent. Therefore, the steel pile is embedded in the alkaline mixture. The corrosion is prevented even if the ground is acidic.

Also, there is no need to remove the excavated soil from the excavation hole,
The excavated soil can be mixed with a liquid material such as cement milk to relax the ground, so that noise and vibration can be suppressed, and the drilling torque can be reduced to form a large-diameter borehole. And can cast large diameter steel piles.

In addition, by mixing the liquid material, the frictional resistance between the steel pile and the excavated soil can be greatly reduced, making it easy to insert the steel pile and preventing the steel pile and surface treatment from being damaged. And the corrosion prevention effect can be enhanced.

As described above, the corrosion of the steel pile can be prevented, so that the corrosion allowance can be underestimated and the cost can be reduced.

In particular, by mixing the excavated soil and the alkaline solidifying agent with the granular powder aggregate, solidification of the admixture can provide a strong pile supporting force.

In addition, since the excavated soil is not discharged, it is not necessary to perform the discharging process, and the cost of driving the steel pile can be reduced.

(F) Example An example of the present invention will be described with reference to the drawings.

FIG. 1 shows a steel pile driving device (A) for carrying out the present invention, which is constituted by a movable base machine (1) and a solidifying agent supply device (2). The base machine (1) vertically supports the rotation axis (4) by the reader (3), and rotates the rotation axis (4) by the motor (5) interposed between the reader (3) and the rotation axis (4). ) And lowering the coaxial (4) along the leader (3) while rotating the excavating blade (6) and the stirring blade (7) connected to the lower end of the coaxial (4), so as to be perpendicular to the ground (G). The drilling hole (H) is formed.

As shown in FIG. 2, the rotating shaft (4) is composed of a double shaft, that is, a hollow tubular outer shaft (9), and an inner shaft (10) inserted through the outer shaft (9). The inner and outer shafts (10) and (9) are configured to rotate in opposite directions by a contra-rotating gear mechanism (11) interposed between the upper end of the rotating shaft (4) and the motor (5). And the inner shaft (10) is the outer shaft (9
An excavating blade (6) extends further downward than the lower end of the inner shaft (10).

A stirring blade (7) is disposed above the excavating blade (6), and the stirring blade (7) is composed of large, medium, and small stirring blades (7a) (7).
b) (7c), composed of large and medium stirring blades (7a)
(7b) is a substantially trapezoidal frame when viewed from the side, with small stirring blades (7c)
Are formed in a rectangular plate shape, and a predetermined number of them are radially arranged around the rotation axis (4).

The small stirring blade body (7c) is loosely fitted to the lower end of the outer shaft (9), and has a stopper (37a) (37b) whose rotation range relative to the outer shaft (9) is restricted. ), The middle stirring blade body (7b) surrounds the outer circumference of the small stirring blade body (7c), and the upper end is loosely fitted to the outer circumference of the outer shaft (9), and the lower end is outer shaft (9). The large stirring blade (7a) surrounds the outer periphery of the middle stirring blade body (7b), and the upper end is fixed to the outer periphery of the outer shaft (9), and the lower end is fixed to the inner shaft (10). It is loosely fitted on the outer circumference.

Therefore, the large and small stirring blades (7a) (7b)
c) and rotate in the opposite direction.

At the upper end of the rotating shaft (4), a granular aggregate feeding device (B) shown in FIG. 2 is provided, and (35) is a measuring device for the granular aggregate. 35) Below the outer shaft (9)
A hopper (14) communicating with the inside of the coaxial (9) is provided at the upper end of the shaft, and a screw (15) is provided around the outer peripheral surface of the inner shaft (10) below the hopper (14), so that a substantially conical conveyance Tube (16)
Around the lower end of the screw (15), the lower end of the transport inner cylinder (16) is notched obliquely, and the granular aggregate discharge valve (36) provided below the transport inner cylinder (16) The granular aggregate that falls and accumulates does not rise above the upper end of the diagonal notch opening at the lower end of the transport inner cylinder (16) due to the self-regulating action. Like that.

The granular aggregate discharge valve (36) is provided with a valve plate (36a) inside the floating outer cylinder (37), and a valve is provided on the valve plate (36a) and the peripheral surface of the outer cylinder (37). Drill the mouth (36b) (36c)
Below the valve plate (36a), a substantially valve-shaped valve box (36d) is provided and fixed to the outer periphery of the inner shaft (10). By drilling (36e) and (36f), the relative rotation of the inner shaft (10) and the outer shaft (9) is switched between forward and reverse,
The valve ports (36b), (36c), (36e), and (36f) can be opened and closed to discharge the granular aggregate from the granular aggregate input device (B) to the vicinity of the small stirring body (7c). Or it can be stopped.

Below the granular aggregate discharge valve (36), a lower discharge valve (27) and a side discharge valve (32) of the soil conditioner injection device (C) shown in FIGS. 3 to 5 are provided. ing.

The side discharge valve (32) has a bottomed cylindrical shape having substantially the same outer diameter as the outer edge (9), the upper opening edge slidably contacting the outer edge (9) and the lower edge, and the inner shaft (10) on the bottom surface. ) Is inserted in a loosely fitted state, a side rotation valve port (32b) is formed in the side surface of the side discharge valve (32), and a shutter (32) protruding from the outer periphery of the inner shaft (10) is provided.
In a), the side rotation valve port (32b) is opened and closed.

In the figure, (32c) and (32c) are stoppers, and the inner shaft (10)
The rotation of the shutter and the relative rotation range of the shutter (32a) due to the resistance of the excavated soil acting on the side discharge valve (32) are maintained, and the open / closed state of the side rotation valve port (32b) is held at either one Then, the solidifying agent supplied between the outer shaft (9) and the inner shaft (10) is injected into the excavated soil from the side rotation valve port (32b) or stopped.

The lower discharge valve (27) is rotatably fitted with a bottomed substantially cylindrical lower discharge valve (27) inside the inner shaft (10) at substantially the same vertical position as the lower end of the outer shaft (9). And the lower discharge valve (2
A disk (12) is provided below 7) to support the lower discharge valve (72), and a substantially sector-shaped lower fixed valve port (27a) and a lower part are provided on the bottom surfaces of the disk (12) and the lower discharge valve (27), respectively. Rotating valve port (27
b), and a projection (27c) protruding from the outer periphery of the lower discharge valve (27) and an engaging body (27d) protruding from the inner bottom surface of the side discharge valve (32) are engaged. The lower discharge valve (27) is rotated substantially integrally with the side discharge valve (32), and both valve ports (27a) (2
When 7b) coincides, the solidifying agent supplied into the inner shaft (10) is supplied from the lower discharge hole (27e) provided near the excavating blade (6) at the lower end of the inner shaft (10) to the drilling hole (H). ).

Also, an internal discharge valve port (27f) is formed in the peripheral wall of the lower discharge valve (27) and the peripheral wall of the inner shaft (10) so that the opening and closing operation can be performed simultaneously with the side discharge valve (32). ing.

In FIG. 2, reference numeral (40) denotes a discharge port of a slurry-like solidifying agent such as cement milk, which works in conjunction with a granular aggregate discharge valve (36) and a lower discharge valve (27) to form a slurry. The solidifying agent is discharged into the agitated soil.

Therefore, when the inner shaft (10) is rotated in one direction, the lower discharge valve (27) closes, the side discharge valve (32) opens, and the solidifying agent is removed from the vicinity of the lower end of the small stirring blade (7c). When injected and rotated in the opposite direction, the side discharge valve (32) closes, the lower discharge valve (27) opens, and the slurry-like solidifying agent is injected from the vicinity of the drilling blade (6). Become.

As described above, by switching the rotation direction of the inner shaft (10), the injection of the granular aggregate and the injection position of the solidifying agent can be switched up and down. In improving the soft ground,
The excavation hole (H) is obtained by injecting a powdered aggregate having good fluidity such as sand into the excavated soil and then injecting a slurry-like solidifying agent such as cement milk while switching the upper and lower injection positions.
A mixture (K) in which the excavated soil, the granular aggregate and the slurry-like solidifying agent are mixed extremely uniformly can be generated.

Next, as shown in FIG. 6, a steel pile (S) is driven into the mixture (K) in the excavation hole (H) by using a lifting device (L) such as a crane. Since the admixture (K) is a mixture of excavated soil, granular aggregate, and slurry-like solidifying agent in a very uniform manner, the lower end of the steel pile (S) is brought to the bottom of the excavation hole (H) only by its own weight. Can sink.

The steel pile (S) cast in this way exerts a supporting force as a pile by solidifying the admixture (K).

In particular, by using an alkaline solidifying agent such as cement milk as the solidifying agent, the steel pile is buried in the solidified alkaline mixture, preventing corrosion of the steel pile even if the ground is acidic. Is done.

Further, by mixing the granular powder aggregate with the excavated soil and the alkaline solidifying agent, the support of the steel pile (S) can be increased by solidifying the mixed material.

In addition, since the ground can be relaxed by mixing a liquid substance such as cement milk into the excavated soil, it is possible to suppress the generation of noise and vibration, and also to reduce the excavation torque to reduce the diameter of the excavated hole. A large diameter steel pile (S) can be cast.

Further, the frictional resistance between the steel pile (S) and the excavated soil can be greatly reduced by mixing the slurry-like solidifying agent, so that the steel pile (S) can be easily inserted and the steel pile (S) can be easily inserted. ) The surface and the rust preventive treatment applied to the surface can be prevented from being damaged, and the corrosion prevention effect can be enhanced.

As described above, the corrosion of the steel pile (S) can be prevented, so that the corrosion allowance can be underestimated and the cost can be reduced.

In particular, by mixing the excavated soil and the alkaline solidifying agent with the granular powder aggregate, solidification of the admixture can provide a strong pile supporting force.

In addition, since it is not necessary to carry out the excavated soil from the excavation hole (H), it is not necessary to perform an excavation process, and it is possible to reduce the cost of driving a steel pile.

FIG. 7 shows another embodiment, in which a mixture (K) of excavated soil, granular aggregate and a slurry-like solidifying agent is formed in a borehole (H), and then a thick concrete (K1) is formed. Is injected using an injection pipe (P), and the concrete (K1) is settled at the bottom of the excavation hole (H) by utilizing the specific gravity difference with the mixture (K). By casting
By forming a solid concrete block at the lower end of the steel pile (S), the vertical supporting force of the pile (S) is increased.

The steel pile (S) has a steel pipe pile,
There are H-shaped piles, deformed section piles, etc.
The present invention can be applied to a steel material cast on the ground.

[Brief description of the drawings]

FIG. 1 is an overall side view of a steel pile driving device for carrying out the present invention, FIG. 2 is a longitudinal sectional view of a ground improvement agent injection device, and FIG.
The figure is an enlarged sectional view of the essential part, and FIGS. 4 and 5 are FIGS.
-I sectional view (open and closed state diagram of the lower and side discharge valves), sixth
The figure is an explanatory view showing the situation of driving a steel pile, and FIG. 7 is an explanatory view showing another embodiment. (G): Ground (H): Drilling hole (K): Admixture (S): Steel pile

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Claims (1)

(57) [Claims] An excavated soil in an excavation hole (H) drilled in a ground (G) at a casting site is mixed with a granular aggregate and an alkaline solidifying agent. Drilling holes before solidification (H)
A method for preventing corrosion of cast-in-place steel piles, wherein a steel pile (S) is inserted therein.