JPH076190B2 - Pile construction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for constructing a foundation pile by building a ready-made pile as a core material.

[Conventional technology]

Conventionally, an existing pile construction method called a vibration-free and noise-free pile driving method is to drill a hole, fill the hole with mortar, and then build the pile. In this case, care must be taken to prevent the collapse of the hole wall during excavation, the connection between the pile to be built and the support ground, and the securing of the core position of the pile to be built.

[Problems to be Solved by the Invention]

Since the conventional construction method is to build the pile after filling the mortar as described above, it is not necessary to hit with a monken etc. to insert the pile at all, and it can be said that it is completely vibration-free and noise-free. Often not. Driving with such a monken may lead to damage to the pile or adversely affect the straightness accuracy.

Further, a casing construction method in which a steel pipe casing is built in order to prevent collapse of the hole wall during excavation is also known. For this, for example, a casing is arranged on the outside of an auger screw, and the casing is inserted at the same time as excavation with the auger screw. However, it is impossible to prevent the wall of the hole from collapsing when the casing is pulled out, and there is no established technique for accurately disposing and fixing the pile inside the casing.

The object of the present invention is to eliminate the inconvenience of the conventional example, and to completely prevent the collapse of the hole wall by consolidating the hole wall, and at the same time, the ready-made pile and the ground can be integrated through the mortar, and at a large depth. An object of the present invention is to provide a method of constructing a pile that can be excavated, can be connected to a support ground and a ready-made pile without hitting with a monken, etc., and can be installed with high accuracy.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention has a cutting head whose outer peripheral surface is divided into a vertical swirl groove forming portion and a thick rolling portion, and the casing body and the head are inside a hollow double wall. A liquid supply pipe also serving as an air supply pipe is provided, the lower end of which faces the lower end of the cutting head as a spout, and a rotating casing in which a down-the-hole hammer can be mounted is used in this portion. The inside of the pile is excavated and excavated by excavating means such as an excavating bucket that is inserted from the upper end opening of the casing to a predetermined depth while consolidating the hole wall, and then a prefabricated pile with a spacer provided on the outer periphery of the casing is used as a core material. Built as
The gist of the present invention is to pour out a solidifying material such as mortar from the tip of the cutting head to fill the inside of the hole and pull out the casing according to the filling degree of the solidifying material such as mortar.

[Action]

According to the present invention, when the casing is installed while rotating, the earth and sand scraped by the cutter bit on the lower end surface of the head is extruded to the outside of the head, and a part of the earth and sand is compacted on the hole wall by the rolling portion on the outer peripheral surface. To be done. Further, the remaining earth and sand is guided to the groove of the swirl groove forming portion and ascends, and is compacted on the hole wall by the rolling portion.

By consolidating the hole wall in this way, the friction on the casing peripheral surface is removed, drilling at a large depth is possible, and an impermeable layer can be formed, so it is possible to construct cast-in-place piles even at high groundwater flow rates. It will be possible.

Furthermore, in addition to the above-mentioned compaction action, the pouring outlet is closed and the liquid supply pipe is used as an air supply pipe to supply compressed air to this down-the-hole hammer, thereby excavating the cutter bit and down-the-hole hammer together, and excavating hard ground efficiently. Is possible.

Further, the existing pile as a core material to be built in the casing can secure a predetermined position in the casing by a spacer provided on the outer periphery, and further, the casing can be installed as a guide with high accuracy.

By injecting a solidifying material such as mortar between the pile and the hole wall, the pile and the ground are integrated without impact, but the consolidated hole wall and the solidifying material such as mortar make the pile more solid in the ground. Set.

Since the casing is pulled out in accordance with the filling degree of the solidifying material such as mortar, the solidifying material such as mortar can be filled with the solidifying material without fail even in the position where the casing existed.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partially cutaway front view showing an embodiment of the pile construction method of the present invention. First, the device used in the present invention method will be described.

In the figure, 2 is a casing main body having a double wall made of steel pipe, and 1 is a cutting head which is fitted to the tip of the casing main body 2 and fixed by bolting.

As shown in FIGS. 8 to 10, the cutting head 1 is composed of a double-walled short cylinder like the casing body 2.
A fitting joint 3 for the casing body 2 is formed at the upper end thereof, and a cutter bit 4 is planted at the lower end surface thereof.

The outer peripheral surface of the cutting head 1 is divided into a swirl groove forming portion in which a ridge 5 is provided in a concave portion and a swirl groove 6 is formed between the concave portion and a rolling portion 7 which is slightly thick and protrudes slightly outward from the casing body 2. In the illustrated example, the turning groove forming portion and the rolling portion 7 are formed so as to face each other.

The rolling section 7 is formed in a scented ball shape having a tapered cross section with respect to the rotation direction and has a tapered surface 7a. Through this tapered surface 7a, the excavated earth and sand can be pressed outward by rotation. I am doing it.

Several of the ridges 5 are cut in the middle to form lateral grooves 8 for allowing gravel or the like to escape.

The casing main body 2 and the head 1 are provided with a liquid feed pipe 10 inside the double-walled hollow, and the lower end thereof faces the lower end of the head 1 as a spout 9. Further, a swivel device 11 is attached to the upper end of the liquid supply pipe 10, and a liquid supply pipe 13 from a solidification material manufacturing plant 12 such as mortar can be connected thereto.

The liquid feed pipe 10 can also be used as an air feed pipe, and a down-the-hole hammer (air hammer) 22 driven by air is attached to the lower part of the liquid feed pipe 10.

Fitting joints are provided on the lower end of the casing body 2 and the upper end of the cutting head 1, respectively. The fitting joint portion forms a plurality of concave portions on the outer periphery of the lower end of the casing body 2 at intervals in the circumferential direction, and a plurality of convex portions on the outer periphery of the upper end of the cutting head 1 at intervals in the circumferential direction. , The casing main body 2 by fitting these concave and convex portions together.
The cutting head 1 and the cutting head 1 are detachably attached.

Then, the normal cutting head 1 is replaced with the cutting head 1 having the down-the-hole hammer (air hammer) 22.

This down the hole hammer (air hammer) 22
The pouring outlet 9 at the lower end of the liquid supply pipe 10 of the cutting head 1 is closed, and compressed air is supplied by using the liquid supply pipe 10 as an air supply pipe to vibrate the cutting head 1 portion by the compressed air.

As described above, in the present invention, in addition to the excavation of the cutting head 1, the combined use of the down-the-hole hammer 22 is possible.

Reference numeral 14 in the drawing denotes a casing builder, which supports a casing drive unit 15 including a motor, a speed reducer, and a casing chuck mechanism rotated by these, with the lifting jack 16 as a leg.

11 to 13 show a spacer 18 attached to the outer periphery of a prefabricated pile 17 such as a steel pipe, H-shaped steel, and concrete pile,
This is a band type in which semicircular metal strips are combined and connected by bolts and nuts 18b, and as shown in FIG. 13, they are located at the center when the prefabricated pile 17 is inserted into the casing body 2 and have an appropriate interval. A vertical collar plate 18a is provided so as to be capable of holding the radial projections.

Next, the method of the present invention performed using such an apparatus will be described.

2 to 7 are vertical front views showing respective steps, in which the casing main body 2 is set in the casing drive unit 15 of the casing builder 14 so that the outer periphery of the casing main body 2 is fixed by a chuck mechanism, When the motor is started, the chuck mechanism rotates via the speed reducer, and the casing body 2 pressed by the chuck mechanism and the cutting head 1 at the tip thereof.
Also slowly rotates in one direction.

As shown in FIG. 2, the lower end surface of the head 1 is ground with a cutter bit 4 or down the hole hammer 22,
It is cut into the ground.

The earth and sand and stone debris cut by the cutter bit 4 are extruded to the outside of the head 1, and a part of it is compressed by the rolling portion 7 of the head 1.
The hole wall is consolidated with. Further, the remaining earth and sand and the like rise along the swirling groove 6 and are compacted on the hole wall by the compaction portion 7.

The elevating jack 16 is free, and when the head 1 and the casing body 2 are built in the ground in this way, the casing drive section 15 also descends by its own weight, but when it reaches the lowest position, the chuck mechanism is reached. Is loosened once and the elevating jack 16 is extended to push up the drive unit 15, the upper part of the casing body 2 is fixed again by the chuck mechanism, and the same operation is repeated.

On the other hand, the earth and sand sliced in the head 1 is suspended from above by excavating the excavation means 19 such as a hammer grab or another excavation bucket into the casing body 2 and excavated and discharged.

To further explain the consolidation of the hole wall, since the cutting head 1 is connected to the tip of the rotary casing body 2, a part of the earth and sand cut by the cutter bit 4 and the down the hole hammer 22 is immediately transferred to the hole wall. Be consolidated. Usually, the void ratio is about 60 to 70% in the loam layer, about 35 to 45% in the sand layer, and about 25 to 35% in the gravel layer. According to the head 1 of the present invention, the voids are consolidated close to the consolidation limit of each layer. Then, the impermeable layer can be formed. Further, since the soil compaction action is performed only by the tip portion of the casing body 2, it is possible to reduce the frictional resistance at the time of excavation to the peripheral surface of the casing body 2 and realize an efficient drilling. Since it is not provided in the entire length of the casing body 2 but only in the head 1 at the tip, no extra load is applied when the casing rotates, and excavation at a large depth is possible.

Further, the down-the-hole hammer 22 effectively works for excavating the hard supporting ground 20 such as rock.

After excavation to a predetermined depth reaching the supporting ground 20 as shown in Fig. 3, as shown in Fig. 4, a spacer is provided on the outer circumference.
The casing body 2 and the casing body 2 are provided in the casing body 2 and the cutting head 1 by using the ready-made piles 17 with the upper and lower 18 mounted as core materials.
Install from the top opening of. This building is the casing body 2
With the collar plate 18a, the prefabricated pile 17 is located at the center position in the casing body 2 and accurately.
And keeps an appropriate interval and fits.

Next, as shown in FIG. 5, a swivel device 11 is attached to the upper end of the liquid feed pipe 10, and a liquid feed pipe 13 from a solidification material manufacturing plant 12 for mortar or the like is connected to the swivel device 11 and fed from the plant 12. A solidifying material 21 such as mortar is poured from the spout 9 to the lower end of the head 1.

The solidifying material 21 such as mortar collects in the hole from the bottom and is filled up. At the same time, the casing builder 14 is driven by the operation opposite to that at the time of the erection to drive the casing body 2 and the cutting head 1. Pull out. (See FIG. 6) In this way, the construction is completed by injecting the solidifying material 21 such as mortar to the upper portion of the hole as shown in FIG. 7 while pulling out the casing.

〔The invention's effect〕

As described above, the method of constructing a pile of the present invention can completely prevent the collapse of the hole wall by consolidating the cutting head hole wall at the tip of the casing body, remove friction on the casing peripheral surface, and excavate a large depth. In addition, because the impermeable layer can be formed, cast-in-place piles can be constructed even when the groundwater velocity is high.

In addition, it is possible to integrate the prefabricated pile as the core material and the ground through a solidifying material such as mortar, and since excavation at a large depth is possible, the connection between the support ground and the prefabricated pile is good, and as a construction procedure, By injecting a solidifying material such as mortar between the hole walls, the pile and the ground will be integrated without hitting, and the compacted hole wall and the solidifying material such as mortar will set the ready-made pile for further strengthening in the ground. It

In addition, the existing pile as a core material to be built in the casing can secure a predetermined position in the casing by the spacer provided on the outer periphery, and the casing can be used as a guide for high-precision installation, and a pile with good construction accuracy can be obtained. Is what you get.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of a pile construction method of the present invention, FIGS. 2 to 7 are vertical front views showing respective steps, and FIG. 8 is a side view of a cutting head. 9 is a front view of the same, FIG. 10 is a cross-sectional plan view of FIG. 9, FIG. 11 is a perspective view of a spacer, FIG. 12 is a plan view of the same as above, and FIG. 13 is a plan view showing the relationship between the spacer and the casing. Is. 1 ... Cutting head, 2 ... Casing body, 3 ... Fitting joint, 4 ... Cutter bit, 5 ... Ridge, 6 ... Turning groove, 7 ... Rolling section, 7a ... Tapered surface, 8 ... Lateral groove , 9 ...... Spout 10 …… Liquid supply pipe 11 …… Swivel device, 12 …… Plant 13 …… Liquid supply pipe, 14 …… Casing installation machine 15 …… Casing drive 16 …… Elevation jack, 17 ・ ・ ・… Prepared pile 18 …… Spacer, 18a …… Temp plate 18b …… Bolt / Nut 19 …… Drilling means, 20 …… Supporting ground 21 …… Solidifying material such as mortar, 22 …… Down the hole hammer

Claims (1)

[Claims] 1. A cutting head, the outer peripheral surface of which is divided into a vertical swirl groove forming portion and a thick rolling portion, wherein the casing body and the head are fed into a hollow inside of a double wall to serve also as an air feeding pipe. A liquid pipe is provided, the lower end of which faces the lower end of the cutting head as a spout, and a rotating casing in which down the hole hammer can be attached is used in this part.
When the rotating casing is installed, the inside of the casing is inserted from the upper end opening of the casing by an excavating means such as an excavating bucket and excavated, the soil is excavated to a predetermined depth while compacting the hole wall, and then a spacer is provided inside the casing on the outer periphery. Built with the existing pile as a core material, the solidification material such as mortar is poured out from the tip of the cutting head to fill the inside of the hole, and the casing can be pulled out according to the filling degree of the solidification material such as mortar. Characteristic pile construction method.