JPS64532B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a construction method of piles cast on site, and is used for supporting structures, etc.

[Conventional technology]

The conventional pile construction method is a non-polluting method that does not produce vibrations, noise, or waste such as bentonite mud, and excavates to a specified depth with an earth auger, and injects mortar from the tip of the bit.
Widely used methods include the PIP method, in which the inner pipe used as the injection pipe is pulled out to create a mortar pile, and the MIP method, in which soil cement piles are created by mixing the earth and sand at the pile placement location with cement milk spouted from the tip of the bit. Are known.

[Problem that the invention seeks to solve]

However, the conventional cast-on-site pile construction method has a problem in that it is difficult to perform construction management as with ready-made piles. In other words, in the case of ready-made piles, the strength of the piles can be confirmed in advance, and if a pile driver is used, it is relatively easy to calculate the estimated bearing capacity of the ground and piles from the relationship between the driving force and the amount of sinking. However, with the conventional pile pile construction method, the only way to estimate it is based on the amount of settlement, etc. through post-construction surveys, and the actual strength of the pile itself cannot be obtained through mixing tests on the ground, so it is not reliable. Scarce;
In some cases, it is being used wastefully.

The construction pile construction method of the present invention was invented to solve these problems, and when constructing the construction pile, the inner pipe serving as the injection pipe can be moved by a predetermined amount in the vertical direction with respect to the casing. The purpose of this is to gradually pull out the casing while injecting a hardening material into the casing when the drilling device is pulled out, thereby obtaining a highly reliable formed pile of excellent quality.

[Means for solving problems]

In the pile construction method of the present invention, the inner pipe 12 is supported by a hydraulic cylinder 27 or the like so as to be movable in the vertical direction by a predetermined amount with respect to the casing 11, and when the drilling device is pulled out, the lower end of the inner pipe 12 is pulled into the casing 11. Since the hardening material 2 such as mortar is injected into the casing 11, uniform injection is possible, and reduction of the pile cross section and deterioration of the quality of the hardening material 2 can be prevented.

In construction, first, the casing 11 as an outer pipe and the inner pipe 12, which also serves as an injection pipe, are rotated as a unit and are sunk along the leader mast 30 to form a hole. During this drilling, the lower end of the inner tube 12 protrudes from the casing 11, and the bit 18 at the tip
Excavation is carried out by such methods. The hardening material 2 is injected at the time of lifting, and as described above, the inner tube 12 is pulled up a predetermined amount relative to the casing 11, and the casing 1 is
The injection is carried out while simultaneously pulling up the tube 1 and the inner tube 12.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

1 to 3 show an example of a construction pile driving device, in which a support frame 20 supporting a drilling device 10 moves up and down along a leader mast 30.

This perforation device 10 has a casing 1 as an outer pipe.
1 and an inner pipe 12 which also serves as a mortar injection pipe, and at the tip of the inner pipe 12 there is an opening/closing shoe 14 as shown in FIGS.
8th grade is attached. In the figure, 13 is a stabilizer, and 17 is a head that pushes the excavated earth and sand to the side.

The drilling is performed by transmitting the rotation of a drive motor 21 fixed to a support frame 20 to the casing 11 via a ring gear (22 in the figure indicates a ring gear box).
This is done by rotating the casing 11 and the inner tube 12 fixed to the casing 11 as one body.
The upper end of the inner tube 12 is supported via a hydraulic cylinder 27 provided on the support frame 20, and the inner tube 12 is supported with a swivel box 26 against the casing 11.
It is possible to move a predetermined amount in the vertical direction. Also,
In the figure, reference numeral 16 denotes a connecting tube, in which a hardening material 2 such as mortar is fed into the inner tube 12 and injected into the ground 1 or the casing 11 from the tip of the inner tube 12.

When the hydraulic cylinder 27 is retracted as shown in FIG. 8b, the inner tube 12 is pushed downward with respect to the support frame 20, and as shown in FIGS. The groove 43 and the locking part 42 at the lower end of the casing 11 engage, and the inner tube 1
2 is fixed to the casing 11 and rotates as a unit during drilling. Further, the upper part of the inner tube 12 is a square tube 15 made of a square steel pipe or the like, and serves as a kelly bar.

The perforation device 10 is raised and lowered by means of spur teeth or racks 3 in the longitudinal direction of a leader mast 30 held vertically.
1, a pinion 25 that meshes with the pinion 25 is attached to the upper part of the support frame 20, and a drive motor 24 is installed.
This is done by Further, a roller 23 is attached to the support frame 20, and is adapted to run within a guide groove 32 formed in the leader mast 30 when moving up and down.

In addition, the tip of the inner tube 12 is centered around the hinge 41,
Generally, a type in which three shoes 14 open and close is used, but there are also types in which a point 45 attached to the tip is left in the ground when the hardening material 2 is poured, as shown in Fig. 7b. Available.

Figures 4a to 4i show an example of the construction process according to the construction method of the present invention, and the work is carried out in the following steps.

a. Retract the hydraulic cylinder 27 and remove the casing 11.
and the inner pipe 12, set it on the stake and check the verticality.

b Rotate the casing 11 and apply pressing force,
The soil at the tip is forcibly moved to the side and deposited.

c When the casing 11 reaches a predetermined depth, fix the casing 11, pressure-inject the hardening material 2 such as mortar from the tip of the inner tube 12, and deepen the depth by a length (0.5 to 1.0 m) equal to the amount of hardening material 2 injected. tube 12
pull up. Note that the hardening material 2 such as mortar is mixed and kneaded in advance and then pumped.

d, e Curing material 2 is continuously injected in a predetermined amount. Further, the pulling speed of the casing 11 is set to be a speed smaller than the injection volume, so that a downward pressing force is applied to the injected hardening material 2. In addition, construction management will be conducted using injection pressure.

f, g After the injection of the hardening material 2 is completed, reinforcing bar baskets 4 or H-shaped steel, L-shaped steel, etc. are inserted as necessary.

h The construction of the stake 3 is completed by the hardening of the hardening material 2.

5A to 5E show the relationship between the injection amount of the hardening material 2 and the pulling length of the inner tube 12 and the casing 11.

That is, in a, when the inner tube 12 is pulled up to a predetermined height by the hydraulic cylinder 27, and an amount of hardening material 2 equal to the lifted height is injected, in b, while the inner tube 12 and the casing 11 are further pulled up, When an amount of hardening material 2 equal to the pulling length is injected, c and d have a pulling length of 80% and 50% of b, respectively, and when the same amount of hardening material 2 is injected, e does not pull up the casing. This is the case where the same amount of hardening material 2 is directly injected. If you do it like c, d, e,
It is also possible to form an enlarged portion at the tip or midway of the pile 3 to increase the tip support force and the circumferential surface friction force.

〔Effect of the invention〕

In the pile construction method of this invention, the inner pipe is made movable by a predetermined amount relative to the casing, and when drilling, the lower end of the inner pipe protrudes from the casing and is excavated with a lower end bit, and during injection, the inner pipe is retracted into the casing. Because the injection of mortar, etc. is carried out inside the casing, which is gradually pulled up, the casing becomes a sliding form, and the hardened material flows through the cracks, reducing the diameter of the pile, or degrading the quality of the hardened material. This makes it possible to create highly reliable piles without having to do anything.

[Brief explanation of drawings]

Fig. 1 is a front view of a pile driving device according to an embodiment of the present invention, Fig. 2 is a right side view thereof, Fig. 3 is a cross-sectional view of Fig. 2, and Figs. 4 a to h are pile construction procedures. A sectional view showing an example of FIG. 5 a, b, c,
d and e are cross-sectional views showing the relationship between hardening material injection amount and casing pull-up length, and Figures a, b, c, d, and e are front views, bottom views, and cross sections of the tip of the pile driving device, respectively. Figures 7a and 7b are front views and longitudinal sectional views showing an example of the tip of the inner tube, respectively, and Figures 8a and b are front views showing the mechanism for raising and lowering the inner tube. It is a diagram. DESCRIPTION OF SYMBOLS 1... Ground, 2... Hardened material, 3... Pile, 4... Rebar cage, 10... Drilling device, 11... Casing, 12...
Inner tube, 13... Stabilizer, 14... Tip opening/closing shoe, 15... Rectangular tube, 16... Connection tube, 17... Head, 18... Bit, 20... Support frame, 21... Rotation drive motor, 22... Ring gear box, 23 ...Roller, 24...Elevating drive motor, 25...Pinion, 26...Swivel box, 27...Hydraulic cylinder, 30...Leader mast, 31...Rack, 32...Guide groove, 4
1... Hinge, 42... Locking part, 43... Locking groove, 44
...Connection piece, 45...points.

Claims (1)

[Claims] 1. A drilling device having a casing as an outer tube and an inner tube that also serves as an injection tube is sunk to a predetermined depth along the leader mast while rotating, and when pulled out, a hardening material is press-fitted from the tip of the inner tube to harden it. In the construction pile method, which creates piles by hardening the material, the inner pipe is supported so as to be movable in the vertical direction by a predetermined amount relative to the casing, and when drilling, the lower end of the inner pipe protrudes from the casing, and the lower end bit is used to excavate the pipe, and the drilling equipment A pile construction method characterized by gradually pulling out the drilling device while injecting a hardening material into the casing from the lower end of the inner pipe with the lower end of the inner pipe retracted into the casing.