JPH0130972B2 - - 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 this invention was invented to solve these problems, and when constructing the construction pile, it controls the sinking speed of the drilling device while controlling the pressing force and rotation applied to the device at this time. The system is designed to calculate the estimated bearing capacity of piles from the resistance, and enables sufficient construction management during the construction of piles, with the aim of obtaining highly reliable piles.

[Means for solving problems]

In the pile construction method of this invention, first, while rotating the casing 11 as an outer pipe and the inner pipe 12 which also serves as an injection pipe as one,
It will be sunk to a specified depth along the Note that a digging bit 18 is usually provided at the tip of the inner pipe 12, and a method is adopted in which the earth and sand are pushed laterally by the head 17.
Then, at the time of drawing out, a hardening material 2 such as mortar is press-fitted from the tip of the inner tube 12 to create a hardening material 3 due to hardening of the hardening material 2.

During sinking, the support frame 20 that supports the inner tube 12 and the upper part of the casing 11 is forcibly moved along the leader mast 30 by a drive device, and is sunk downward at a constant speed. At this time, the pressing force and rotational resistance acting on the inner pipe 12 and casing 11 are continuously measured from the load applied to the lifting and rotating drive devices, and by controlling the construction in this way, the pile 3 construction position is determined. By estimating the ground strength for each area, it is possible to immediately calculate the bearing capacity of pile 3 at the time of construction.

〔Example〕

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

1 to 3 show an example of a pile driving device used in the present invention, in which a support frame 20 supporting a drilling device 10 is moved 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 shoe 14 as shown in FIGS. 8a, b or 9a, and an excavation bit 1.
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 12 is retracted, the inner tube 12 is pushed downward with respect to the support frame 20, and the eighth
The bottom stabilizer 1 as shown in Figures a-e
The locking groove 43 provided in the inner tube 3 engages with the locking portion 42 at the lower end of the casing 11, and the inner tube 12 is fixed to the casing 11 and rotates as a unit during drilling. In addition, the upper part of the inner tube 12 is made of a rectangular tube 1 made of a rectangular steel pipe or the like.
5, and is designed to serve as a kelly bar.

The drilling device 10 is raised and lowered by a straight teeth or rack 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 configured to run within a guide groove 32 formed in the leader mast 30 during elevation.

In addition, the tip of the inner tube 12 is centered around the hinge 41,
Generally, the type has three shoes 14 that open and close, but there are also types where the point 45 attached to the tip is left in the ground when the hardening material 2 is injected, as shown in Figure 9b. 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, fix the casing 11 and the inner pipe 12, set it on the pile core, 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 and inject the hardening material 2 such as mortar under pressure from the tip of the inner tube 12 to a length (0.5 to 1.0 m) equal to the amount of hardening material 2 injected. Only inner tube 12
pull up. Note that the hardening material 2 such as mortar is mixed and kneaded in advance and then pumped.

(d) The hardening material 2 is pumped, the casing 11 and the inner tube 12 are stopped until the injection pressure reaches a predetermined pressure, and a knob-shaped enlarged portion 3' is created.

(e) While pumping the hardening material 2, the casing 11 and inner tube 12 are pulled up by a length equal to the injection amount.

(f), (g) Repeat steps (c) to (e) in the same way, and
We will continue to create.

(h) A pile 3 having a plurality of knob-like enlarged portions 3' is created.

(i) Before the hardening material 2 hardens, reinforcing bar cages 4 are inserted as necessary.

In the above work, the position and finished diameter of the enlarged portion 3' are controlled by the type of soil, the length of the casing 11 pulled up (0.2 to 1.0 m), the amount of hardening material 2 injected, and the injection pressure.

FIG. 6 conceptually shows a graph for construction management in the above embodiment.

When sinking the casing 11, the support frame 20 is lowered at a constant speed by the lifting drive motor 24, and the load is determined from the change in current or voltage of the drive motor 24 at this time, and the load is determined as shown in the graph of FIG. The shape shows the change in pressing force at each depth. Similarly, the rotational resistance is shown in the form of a graph from changes in current or voltage in the rotational drive motor 21. From these pressing forces and rotational resistance,
The ground strength and soil quality at each depth can be estimated, providing data for immediately determining the strength and performance of pile 3 during construction.

In addition, when pulling up the casing 11, the pulling speed is adjusted based on the relationship between the injection amount (l/min) of the hardening material 2 and the injection pressure (Kgf/cm ² ), and a predetermined downward pressing force is applied to the casing 11. In this state, the hardening material 2 can be injected. In this way, the hardening material 2 is sufficiently distributed, and the pile 3
This prevents non-uniformity in performance and quality, and provides a highly reliable pile 3. Furthermore, as shown in the graph, when the injection amount of the hardening material 2 is kept constant and the rise of the casing 11 is suppressed (the drive motor 24 is stopped), the injection pressure increases and an enlarged part 3' is formed in this part. be done.

Figures 5a to 5h show the construction in another embodiment, and the work is carried out in the following steps.

(a) Retract the hydraulic cylinder 27, fix the casing 11 and the inner pipe 12, set it on the pile core, 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 and inject the hardening material 2 such as mortar under pressure from the tip of the inner tube 12 to a length (0.5 to 1.0 m) equal to the amount of hardening material 2 injected. Only inner tube 12
pull up.

(d), (e) The hardening 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 completing the injection of the hardening material 2, reinforcing bar cages 4, H-shaped steel, L-shaped steel, etc. are inserted as necessary.

(h) Creation of the pile 3 is completed by hardening of the hardening material 2.

FIG. 7 conceptually shows a graph for construction management in the above embodiment.

When the casing 11 is sunk, construction management is carried out in the same manner as in the previous embodiment.

The casing 11 is pulled up at a constant speed, and the enlarged portion 3' is not provided. In addition, the graph in FIG. 7 shows that the injection pressure is low for the first injection when the tip of the inner tube 12 is pulled up into the casing 11 by the hydraulic cylinder 27, and as the injection depth becomes shallower, the injection pressure decreases. It shows how it grows.

FIGS. 10 and 12 show other embodiments,
This figure shows a pile driving device for leaving the casing 11 underground. In this embodiment, a ready-made auger machine 50 is mounted on a supporting frame 2.
0', and when drilling, the expanding member 51 interposed between the inner tube 12 and the casing 11 is pressed against the inner surface of the casing, and the inner tube 12 and the casing 1 are
1 is rotated as one unit, and when pulling out, the expanding member 51 is pulled toward the inner pipe 12, the casing 11 is left in the ground 1, and the casing 1 is
The hardening material 2 is injected into the inside of the hardening material 1 (see Utility Model Application No. 185216/1983). In this case as well, the load on the drive motors 21' and 24 and the sinking speed of the device are measured during drilling, and the hardening material 2 is
Measures injection pressure, injection volume, equipment lifting speed, etc., and performs construction management.

〔Effect of the invention〕

In the construction method of this invention, the drilling device, which was conventionally simply suspended, is pushed down at a predetermined speed along the leader mast, and the pressing force and rotational resistance applied to the inner pipe and casing are continuously measured. For each pile, the approximate support strength at each depth in the ground can be confirmed during construction, resulting in highly reliable piles. Additionally, this makes it possible to manage construction work, which was difficult in conventional construction using piles.

[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 taken from Fig. 2, and Figs. Cross-sectional view showing the construction procedure of piles, Figure 5 a~
h is a sectional view showing the construction procedure in another example,
Fig. 6 is a graph for construction management corresponding to Fig. 4 a to i, Fig. 7 is a graph for construction management corresponding to Fig. 5 a to h, and Fig. 8 a, b, c, d. ,e
9A and 9B are respectively a front view, a bottom view, and a cross-sectional view of the tip of the pile driving device, a front view of the stabilizer, and a cross-sectional view, and FIGS. , FIG. 10 is a right side view of a pile driving device in another embodiment, and FIG. 11 is a cross-sectional view taken along the line shown in FIG. 10. 1...ground, 2...hardened material, 3...pile, 4...
... Rebar cage, 10 ... Perforation device, 11 ... Casing, 12 ... Inner pipe, 13 ... Stabilizer, 1
4...Tip opening/closing shoe, 15...Square tube,
16...Connection tube, 17...Head, 18...
... Bit, 20 ... Support frame, 21 ... Rotation drive motor, 22 ... Ring gear box, 23 ... Roller, 24 ... Lifting drive motor, 25 ... Pinion, 26 ... Swivel box, 27 ... Hydraulic cylinder, 30 ... Leader mast, 31 ... Rack, 32 ... Guide groove,
41... Hinge, 42... Locking portion, 43... Locking groove, 44... Connecting piece, 45... Point.

Claims (1)

[Scope of Claims] 1. While rotating the casing as an outer tube and the inner tube that also serves as an injection tube, the casing is sunk along the leader mast to a predetermined depth while being rotated as a unit, and when pulled out, a hardening material is press-fitted from the tip of the inner tube. In the construction pile construction method in which piles are created by hardening of hardened material, the inner pipe or a support frame supporting the inner pipe and the upper part of the casing is forcibly moved downward at a predetermined speed along the leader mast during sinking. A pile construction method characterized in that the supporting force at the pile construction position is calculated by continuously measuring the pressing force and rotational resistance applied to the inner pipe and casing at this time. 2 The first claim that the hardening material is mortar
The pile construction method described in section.