JPH02217516A - Pile driving method and excavating casing - Google Patents

Abstract

PURPOSE:To form a prefabricated pile and ground integrally without applying impact, and set the pile at high precision by consolidating a hole wall by using a rotary casing having a cutting head divided into a swing channel forming section and a rolling section. CONSTITUTION:A casing main-body 2 having a cutting head 1 is rotated, and with a cutter bit 4 or a down-the-hole hammer 22, ground is excavated, and excavated earth is consolidated on a hole wall with a rolling section 7 via the swing channel 6 of the head 1 and at the same time, a casing is erected. After that, an excavating means is suspended to be moved down into the casing main-body 2, and internal earth is excavated to be discharged, and a prefabricated pile 17 with spacers 18 fitted on the upper and lower sections of the outer periphery is set to be a core member and is set on the central position of the main body 2 and the head 1. Then, the main body 2 and the head 1 are pulled out, and a space between the prefabricated pile 17 and the hole wall is filled up with the solidifying material of mortar or the like, from an outlet at the lower end of the head 1, and the execution of work is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of constructing a foundation pile by erecting a ready-made pile as a core material.

[Conventional technology]

Conventionally, the method of erecting existing piles, which is referred to as the vibration-free and noise-free pile driving method, involves drilling holes, filling the holes with mortar, and then erecting the piles. In this case, care must be taken to prevent the wall of the hole from collapsing during excavation, to connect the piles to be erected with the supporting ground, and to ensure the core position of the piles to be erected.

[Problem to be solved by the invention]

Since the conventional construction method is to fill the mortar with mortar and then erect the piles as mentioned above, it does not require any impact with a hammer or the like to insert the piles (completely vibration-free, noise-free). Driving with a screwdriver or the like may cause damage to the pile and adversely affect straightness accuracy.

Also known is a casing construction method in which a steel pipe casing is installed to prevent collapse of the hole wall during excavation. This involves placing a casing on the outside of an auger screw, for example, and inserting the casing at the same time as the auger screw is excavating. However, this did not prevent the hole wall from collapsing when the casing was pulled out, and there was also no established technology for accurately arranging and fixing the piles inside the casing.

The purpose of the present invention is to eliminate the disadvantages of the conventional example, to completely prevent the collapse of the hole wall by consolidating the hole wall, to integrate the ready-made pile and the ground through mortar, and to make it possible to operate at great depths. To provide a pile construction method that enables excavation, allows connection of supporting ground and ready-made piles without being hit by a hammer, and allows ready-made piles to be erected with higher accuracy.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a rotary casing having a cutting head whose outer circumferential surface is divided into a vertical swirl groove forming part and a thick rolling part, At the same time, the inside of the casing is excavated and removed using a digging means such as a digging bucket that is inserted through the upper opening of the casing, and the hole wall is excavated to a predetermined depth while compacting, and then a ready-made pile with a spacer provided on the outer periphery is installed inside the casing. A solidifying material such as mortar is poured out from the tip of the cutting head to fill the hole, and the casing is pulled out according to the degree of filling of the solidifying material such as mortar, and the casing body and the head are The main idea is that a liquid supply pipe that also serves as an air supply pipe is installed in the hollow interior of the double wall, and its lower end faces the lower end of the cutting head as a spout, and a down-the-hole hammer can be detachably attached to this part. It is something to do.

[Effect]

According to the present invention as set forth in claim 1, when the casing is rotated and erected, the earth and sand scraped by the cutter bit on the lower end surface of the head is pushed out to the outside of the head, and some of it is on the outer circumferential surface of the casing. It is consolidated into the hole wall in the rolling section. In addition, the remaining earth and sand are guided by the grooves of the swirl groove forming part and rise, and are consolidated on the hole wall by the rolling part.

By consolidating the hole wall in this way, friction on the casing surface is removed, making it possible to excavate to great depths.Also, an impermeable layer can be formed, making it possible to construct cast-in-place piles even in areas where groundwater flows quickly. It becomes possible.

In addition, the prefabricated pile as a core material to be erected inside the casing can be secured at a predetermined position within the casing by the spacer provided on the outer periphery, and the casing acts as a guide, allowing highly accurate installation.

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

According to the present invention as set forth in claim 2, in addition to the compacting action, the spout is closed and the liquid feed pipe is used as an air feed pipe to supply compressed air to the down-the-hole hammer, thereby performing combined excavation with the cutter bit and the down-the-hole hammer. and
Efficient excavation is possible even in hard ground.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

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

In the figure, 2 is a double-walled casing body made of a steel pipe, and 1 is a cutting head that fits into the tip of the casing body 2 and is fixed with bolts.

As shown in FIGS. 8 to 1θ, the cutting head l
Like the casing body 2, it is made of a double-walled short cylindrical body, and a fitting joint 3 to the casing body 2 is formed at its upper end, and a cutter bit 4 is implanted in its lower end surface.

The outer circumferential surface of the cutting head 1 is divided into a turning groove forming part with a protrusion 5 in the concave part and a turning groove 6 between them, and a thick rolling part 7 slightly protruding outward from the casing body 2. In the illustrated example, each pair of swirl groove forming portions and rolling pressure portions 7 are formed to face each other.

The rolling section 7 has a cross-sectional shape that is tapered in the direction of rotation and has a tapered surface 7a, so that the excavated earth and sand can be pressed outward by rotation through this tapered surface 7a. It's Nishide.

Several of the protrusions 5 are cut in the middle to form lateral grooves 8 through which gravel and the like can escape.

The casing main body 2 and the head 1 are provided with a liquid feeding pipe 10 inside the hollow double wall, and the lower end of the pipe 10 faces the lower end of the head 1 as a spout 9. Further, a swivel device 11 is attached to the upper end of this liquid sending pipe 10, so that a liquid sending pipe 13 from a manufacturing plant 12 for solidifying materials such as mortar can be connected thereto.

Note that the liquid feed pipe 10 can also be used as an air pipe, and in the cutting head 1, a down-the-hole hammer (air hammer) 22 driven by air is removably attached to the liquid feed pipe 10. Close the outlet 9 and use the liquid supply pipe IO as the air supply pipe for this down-the-hole hammer 2.
By supplying compressed air to the down-the-hole hammer 22, it is also possible to excavate in combination with the down-the-hole hammer 22.

In the figure, reference numeral 14 denotes a casing erection machine, which supports a casing drive section 15 consisting of a motor, a speed reducer, and a casing chuck mechanism rotated by these, with lifting jacks 16 as legs.

Figures 11 to 13 show a spacer 18 attached to the outer periphery of a ready-made pile 17 such as a steel pipe, H-shaped steel, or concrete pile.
This is a band type in which semicircular metal bands are combined and connected with bolts and nuts 19, and as shown in FIG. Vertical flange plates 18a are provided to protrude radially so as to maintain appropriate spacing.

Next, the construction method of the present invention using such a device will be explained.

FIGS. 2 to 7 are longitudinal sectional front views showing each process, in which the casing body 2 is set in the casing drive unit 15 of the casing installation machine 14 so that the outer periphery of the casing installation 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 held down by the chuck mechanism and the cutting head l at its tip also slowly rotate in one direction.

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

The earth, sand, and stone chips cut by the cutter bit 4 are pushed out to the outside of the head 1, and some of them are transferred to the rolling part 7 of the head 1.
is consolidated into the hole wall. Further, the remaining earth and sand rises along the swirl groove 6 and is compacted onto the hole wall by the rolling section 7.

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

On the other hand, the earth and sand cut into rings in the head 1 are excavated and removed by an excavating means 19 such as a hammer grab or other excavating bucket suspended from above into the casing body 2.

To further explain the compaction of the hole wall, since the cutting blade 1 is connected to the tip of the rotating casing body 2, a portion of the earth and sand cut by the cutter bit 4 and the down-the-hole hammer 22 is immediately absorbed into the hole wall. Consolidated. Usually, the void ratio is about 60-70 in loam layer.
%, about 35-45% in sand layer, about 25-35% in gravel layer
However, according to the head 1 of the present invention, each layer can be consolidated close to its consolidation limit to form an impermeable layer.

In addition, since the soil compaction effect is performed only at the tip of the casing body 2, the frictional resistance during excavation against the circumferential surface of the casing body 2 can be reduced and efficient drilling can be achieved. Since it is not provided along the entire length of the casing body 2, but only on the spatula 1 at the tip, no extra load is applied when rotating the casing, making it possible to excavate at great depths.

In addition, for excavation of hard supporting ground 20 such as bedrock,
The down-the-hole hammer 22 works effectively.

As shown in FIG. 3, once the excavation has been carried out to a predetermined depth reaching the supporting ground 20, as shown in FIG. 1 from the upper end opening of the casing body 2. This erection is carried out with high accuracy using the casing body 2 as a guide, and the ready-made pile 17 is housed at the center position within the casing body 2 and at an appropriate distance from the casing body 2 by the collar plate 18a.

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

This solidified material 21 such as mortar accumulates in the hole from the bottom and is filled upwards, but at the same time, the casing erecting machine 14 is driven in a reverse operation to the erecting operation, and the casing main body 2
and pull out the cutting head 1. (See FIG. 6) In this way, the construction is completed by injecting the solidifying material 21 such as mortar up to the upper part of the hole as shown in FIG. 7 while pulling out the casing.

〔Effect of the invention〕

As described above, the pile construction method of the present invention completely prevents collapse of the hole wall by consolidating the hole wall of the cutting head at the tip of the casing body, and also eliminates friction on the casing surface, allowing for deep excavation. Furthermore, since an impermeable layer can be formed, cast-in-place piles can be constructed even in areas where groundwater flows quickly.

In addition, it is possible to integrate the ready-made pile as a core material with the ground through a solidifying material such as mortar, and since it is possible to excavate to a great depth, the connection between the supporting ground and the ready-made pile is good. By injecting a solidifying material such as mortar between the hole walls, the pile and the ground are integrated without any impact, and the compacted hole walls and solidifying material such as mortar make the ready-made pile more firmly set in the ground. be done.

Furthermore, the prefabricated piles that serve as the core material to be built inside the casing can be secured in a predetermined position within the casing by spacers provided on the outer periphery, and the casing acts as a guide for highly accurate installation, resulting in piles with high construction accuracy. That's what you get.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing one embodiment of the pile construction method of the present invention, FIGS. 2 to 7 are longitudinal sectional front views showing each process, and FIG. 8 is a side view of the cutting head. Fig. 9 is a front view of the same as above, Fig. 10 is a cross-sectional plan view of Fig. 9, Fig. 11 is a perspective view of the 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. It is. 1... Cutting head 2... Casing body 3... Fitting joint 4... Cutter bit 5...
・Protrusion 6 ・Swivel groove 7 ・Rolling part
7a...Tapered surface 8...Horizontal groove
9... Outlet 10... Liquid feeding pipe 11... Swivel device 13... Liquid feeding pipe 15... Casing drive unit 16... Lifting jack F... Ready-made pile 18...
- Spacer 18a... Flange plate 19... Excavation means 20... Supporting ground 21... Solidifying material such as mortar 22... Down-the-hole hammer 12... Plant 14... Casing erection machine

Claims (2)

[Claims] (1) Excavation means such as an excavation bucket that erects a rotary casing having a cutting head whose outer circumferential surface is divided into a vertical turning groove forming part and a thick rolling part, and at the same time inserts the inside of the casing from the upper end opening of the casing. The soil is excavated and removed to a predetermined depth while compacting the hole wall, and then a prefabricated pile with a spacer on the outer periphery is built into the casing as a core material, and mortar etc. is solidified from the tip of the cutting head. A pile construction method characterized by pouring material to fill the hole and pulling out the casing depending on the degree of filling with solidifying material such as mortar. (2) It has a cutting head whose outer circumferential surface is divided into a vertical swirl groove forming part and a thick rolling part, and the casing body and the head have a double-walled hollow interior with a liquid supply pipe that also serves as an air supply pipe. An excavation casing characterized by having a lower end facing the lower end of a cutting head as a spout, and a down-the-hole hammer being detachably attached to this part.