JPS6240487B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention particularly enables continuous excavation even when the excavated ground has hard strata or bedrock, or contains cobblestones or pumice, and minimizes the amount of soil removed. This relates to a drilling method using an auger that can strengthen the walls of the hole.

Conventional augers are known to have spiral blades around the entire length of the auger shaft, and ones that have an auger head attached to the tip of the auger shaft.
When rotary excavation is carried out, the earth and sand rises along the spiral blades and is removed, or if not, the earth and sand packed in a compacted state between the spiral blades is discharged by pulling up the auger and pushed into the ground again. Work efficiency was poor because the work had to be carried out intermittently, using rotary excavation. Moreover, since the excavated earth and sand are discharged to the ground, the work site is not dirty and soil disposal is necessary. In addition, if there is a hard stratum, etc. in the excavated ground, or if cobblestone or pumice is included,
Since the auger head could not cut the excavation, the excavation had to be stopped when it hit a boulder.
If further excavation work is to be carried out, it is necessary to remove the auger from the hole, insert a shaft with a cutter head at the tip, re-set it, and cut the hole again, which ultimately reduces the time required to change the auger and cutter head. The drawback was that it took an extremely long time to drill holes. Furthermore, there were cases in which the perforated wall was damaged, making it undesirable to construct either ready-made piles or cast-in-place concrete piles.

This invention was devised to solve the above-mentioned conventional problems all at once.It is a drilling method using a single auger, and the auger also performs cutting in ground mixed with rock, cobbles, and pumice. At the same time, the excavated soil and gravel made by cutting (hereinafter referred to as excavated soil) are stirred and kneaded with bentonite liquid, etc., if necessary, and this excavated soil is forced into the hole wall. loam layer,
It is possible to reliably consolidate the hole wall close to the consolidation limit of each layer such as sand layer, gravel layer, etc., thus greatly improving construction efficiency and construction quality compared to conventional methods, and almost eliminating the need for soil removal treatment. We have succeeded in providing a drilling method using an auger that can completely eliminate the problem.

Examples of this invention construction method will be described below.

First, the auger shaft 1 in the auger used in this method has its base end 8 connected to the cutter head 1.
It is a stepped shaft with a diameter close to that of the 0.0, and around the small diameter tip 2 of the shaft 1,
Consolidation blades 3 are provided away from the shaft peripheral surface and curved along the circumferential direction, and stirring blades 4 and 4' project radially from the shaft peripheral surface at the tip and base ends of the shaft of the consolidation blades 3.

The consolidation vanes 3 may be continuous in the circumferential direction of the shaft, or may be spaced apart as shown. For its installation, a wide spiral blade 5 is used, which is provided around the shaft with the tip end of the shaft being the screwing direction.

The stirring blades 4, 4' are, for example, spaced apart in the longitudinal direction of the shaft and in the circumferential direction, and are not aligned in the circumferential direction but are alternately oriented in opposite directions. These blades 6 and 7 constitute stirring blades 4 and 4'.

A spiral blade 9 having a small width is provided around the shaft base end 8 when the shaft tip side is the screwing direction.

A cutter head 10 is attached to the tip of the auger shaft 1.

As a whole, the consolidation blades 3, stirring blades 4, 4', and spiral blades 9 are in sliding contact with the wall surface of the hole drilled in the ground by the rotation of the cutter head 10, and the circumferential surface of the shaft base end 8 has a gap of, for example, 100 mm. It is arranged to be close to each other. Motoo stirring blade 4,
4 may be short as long as it has the effect of stirring and kneading the excavated soil.

When carrying out this method, when the auger shaft 1 is pressed into the ground while rotating, the cutter head 10 at the tip of the shaft cuts boulders, etc. in the ground mixed with cobbles and pumice, and in the case of rock, it cuts and drills. Continue to do so. Along with such drilling by the cutter head 10, bentonite liquid is injected as necessary. The stirring blades 4 sufficiently stir and knead the excavated soil, and then the consolidation blades 3 apply this kneaded material to the hole wall to perform the first stage of hole wall consolidation.At this time, the base end of the large diameter shaft prevents excavated soil from rising. Further, the excavated soil remaining in the hole is stirred and kneaded again by the stirring blade 4', and then introduced into the gap 11 between the hole wall and the shaft circumferential surface by the narrow spiral blade 9 of the shaft base end 8, and then introduced into the gap 11 between the hole wall and the shaft peripheral surface. The surface is pressed against the hole wall, thereby forcing the cut gravel etc. into the hole wall in a consolidated state, thereby performing the second stage of hole wall consolidation.

This invention has the above-mentioned structure, and while the hole wall is consolidated in two stages to prevent its collapse, the consolidation blade 3 and the spiral blade 9 can continuously perform linear drilling using the hole wall as a guide. Work efficiency can be significantly improved compared to the conventional auger construction method.
Rather than cutting boulders, etc., they can be effectively used as gravel, etc., which is effective for the second stage of hole wall compaction. In particular, the void ratio is approximately 60 to 70% in loam layers and approximately 35% in sand layers.
~45%, and about 25-35% for gravel layers, but according to this invention, the hole wall can be consolidated close to the consolidation limit of each layer. In addition, since the excavated soil is effectively used to compact the hole walls, it is not discharged to the ground at all, or even if it is discharged, only a small amount of it is discharged, and the work site can be made that much cleaner. Furthermore, since the hole walls are compacted, only a small amount of bentonite liquid is needed, and in some cases it is possible to use spring water without using bentonite liquid.

[Brief explanation of the drawing]

The drawing is a front view illustrating the auger used in the present invention in a construction state with the tip of the cutter head omitted. 1... Auger shift, 2... Shaft tip, 3... Consolidation blade, 4, 4'... Stirring blade, 5...
Spiral wing, 6, 7... wing piece, 8... shaft base end, 9... spiral wing, 10... cutter head.

Claims (1)

[Claims] 1 The auger shaft has a stepped shaft whose base end has a large diameter close to the drilling diameter, and a narrow spiral is formed around the large diameter shaft at the base end of the shaft, with the shaft tip side being the threading direction. A small-diameter shaft is provided with a wing, and a large-width helical wing is provided around the small-diameter tip of the shaft, and a consolidation wing that is separated from the shaft peripheral surface and curved along the circumferential direction is provided at the tip of the large-width helical wing. An auger is provided with stirring blades projecting radially from the circumferential surface, and a cutter head is attached to the tip of the auger shaft, the earth and sand excavated by the cutter head is stirred by the stirring blade, and the soil is consolidated into the perforation wall by the consolidation blade. , a drilling method using an auger, which is characterized by compacting the drilling wall with narrow spiral blades while blocking the rise of earth and sand using a stepped shaft with a larger diameter.