JPH07150874A - Drilling method for soft ground and device used for the method - Google Patents

Abstract

PURPOSE:To prevent settling of a ground through prevention of outflow of sand during a work to drill a soft ground and to improve durability of a slime arresting device. CONSTITUTION:A slime arresting device 1 comprises a cylindrical guide casing part 3, and a cylindrical packer part 2 communicated therewith. Inner flange- form packings 5 and 6 are arranged in two spots separated away from each other by a given distance in the longitudinal direction of the packer part 2. A guide casing part 3 is inserted in a drilled hole 17 in a position lower than a ground and an excavation pipe 21 is inserted in the slime arresting device 1. Water in a storage tank 19 placed on a ground is fed in a pressure chamber 22 formed between the two packings 5 and 6 and a pressure generated by a difference in a level is exerted. A ground around the drilled hole 17 is also about to blow off in the drilled hole 17 owing to a difference in a level from that of a ground. However, as a result of a balance with a water pressure in the pressure chamber 22, a slime is arrested. No sand enters a space between the packings 5 and 6 and the excavation pipe 21 and wear of the packings 5 and 6 owing to sand is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling method for soft ground, and more particularly to a drilling method for reducing the outflow of excavated earth and sand from the drilling, and the durability of the drilling method. High slime fastening device.

[0002]

2. Description of the Related Art When placing an anchor, a hole is drilled in the ground, an anchor cable is inserted into the hole, and a hardening material such as cement paste is injected to fix the anchor. The problem when excavating this hole in soft ground is
This is because the soil in the ground flows out from the drilled holes, causing subsidence. For example, an underground continuous wall may be formed on a soft ground such as sandy ground, and an excavated anchor may be placed from the wall toward the outer ground as the inner ground is excavated. Anchors are placed in order every few meters from the ground, but the anchor to be placed at the lowest position is located several tens of meters below the ground. When drilling a hole, earth and sand (slime state) flow out from the surrounding ground with high pressure (pressured ground) to the hole with low pressure,
A large amount of this spouts from the drilled holes in the wall. If a large amount of earth and sand flowed out through the drilling, it would cause ground subsidence, which was a major problem.

For this reason, at the start of excavation of a drilling hole, a tubular slime fastening device having a packing is attached to the inside of the opening side of the drilling hole, and a drill pipe is inserted into the slime fastening device to continue excavation. Is being carried out. It tries to retain slime flowing out around the drill pipe with packing.

[0004]

However, even if such a slime fastening device is used, the outflow of earth and sand cannot be stopped if the packing is provided at only one place. Since the excavation pipe rotates forward and backward repeatedly to advance the drilling hole, the sand in the slime was caught between the packing and the excavation pipe, and the sand accelerated the wear of the packing. Due to wear of the packing, the gap gradually became larger, and slime sometimes flowed out through this gap. For this reason, the slime fastening device may have to be replaced even during the excavation of one hole.

In addition, the excavation pipe may be pulled out in the middle of excavation for repairing the excavation pipe, etc., but it is not easy work to quickly stop the slime spouting at this time.

The present invention has been made to solve the above problems, and a method for excavating on soft ground for preventing the outflow of slime from a hole to prevent the occurrence of ground subsidence, and a durability method used therefor. An object of the present invention is to provide a slime fastening device having high properties.

[0007]

In the present invention, a slime fastening device having a double packing is used. The slime fastening device comprises a tubular guide casing portion and a tubular packer portion communicating with the casing portion. In the packer portion, packings project in an inner brim shape at two positions spaced apart by a predetermined distance in the longitudinal direction of the cylinder. A hose that connects to the aboveground reservoir is connected between the two packings. Reservoirs may be like tanks or pools of water. Of the two packings, the packing near the guide casing is further provided near the guide casing with a discharge port with a regulating valve capable of discharging excavated soil. Further, on the opening side of the packer portion, a groove is formed on the inner peripheral surface so as to surround the circular opening, and on the side of the packer portion, a slit continuous with this groove is formed. It is possible to insert the plate material from this slit, lock the peripheral edge of the plate material in the groove, and close the opening.

The guide casing portion of the slime fastening device as described above is inserted into a hole drilled at a position lower than the ground, and the packer portion is projected from the ground. The excavation pipe is inserted into this slime fastening device to continue excavation. A pressurizing chamber is formed by the outer peripheral surface of the excavating pipe between two packings of the packer section, and the water in this chamber communicates with the water in the reservoir on the ground through a hose. The earth and sand (slime state) retained by the packing near the guide casing can be discharged from the discharge port.

[0009]

[Operation] The drilling position of the hole is lower than the ground level,
The soft ground, which contains a lot of water around the drilled hole, is also subjected to pressure caused by the difference in height with the ground. Therefore, if the position is considerably lower than the ground level, it will try to go out through the drilling hole connected to the external space with a considerably large pressure. The water in the pressurizing chamber communicates with the water on the ground, and the pressure generated by the difference in height from the ground is also applied. That is, the pressure of the water in the hole to be jetted and the pressure of the water in the pressurizing chamber are balanced, and the slime in the hole is stored in the still water state before the packing. The sand content in the slime is also pressed in front of the packing, and the amount of sand caught between the packing and the outer peripheral surface of the drill pipe is reduced. This also reduces packing wear. When the excavation pipe is removed from the hole during excavation, the plate material is inserted from the slit of the sand retaining part and the opening is sealed by the plate material.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. In the figure, 1 is a slime fastening device, which comprises a packer portion 2 and a guide casing portion 3. The guide casing portion 3 has a cylindrical shape, and a hoop portion 4 is formed on the outer circumference at one end. The packer portion 2 is also tubular and has packings 5 and 6 at two positions separated from each other in the longitudinal direction. The packings 5 and 6 are formed by stacking two to three circular ring-shaped rubber plates, respectively, and the inner diameter is almost the same as the outer diameter of the excavation pipe described later, and it is smaller than other parts. The inner peripheral part projects like an inner collar. The inner diameter of the portion between the packings 5 and 6 is slightly larger than the inner diameters of the packings 5 and 6. A water supply port 7 is formed laterally in this portion. Further, the inner diameter of a portion adjacent to the packing 5 is slightly larger, and a discharge port 8 opening to the side is formed on the outer periphery of this portion, and a regulating valve 9 is attached. At one end of the packer section 2, a tag section 10 is provided on the outer periphery so as to project.

At the other end of the packer portion 2, a horseshoe-shaped shutter frame plate 11 is placed next to the packing 6 next to it.
The diameter of the arcuate inner circumference of the frame plate 11 is slightly larger than that of the packing 6. A circular ring-shaped pressing plate 12 is laid further on the shutter frame plate 11, and a slit 13 is opened to the side of the packer unit 2, and a groove 14 continuous with the slit 13 is formed on the inner periphery of the central portion. Will be formed.

A construction example of the method for boring the underground continuous wall 15 will be described below. A constant length drilling hole 17 is drilled toward the sand ground 16 through the underground continuous wall 15 formed underground. The guide casing portion 3 is inserted into the drilled hole 17 with the tab portion 4 behind and the tab portion 10 of the packer portion 2 is abutted against the tab portion 4 so as to communicate therewith. A rubber band 18 is put on both the hoop portions 4 from the outside, and the guide casing portion 3 and the packer portion 2 are continuous and integrated. The storage tank 19 placed on the ground and the water supply port 7 of the packer unit 2 are connected by a hose 20 so that the water in the tank 19 can fall into the packer unit 2. In the embodiment, the packer section 2 and the guide casing section 3 are separate bodies, but they can be integrated in advance.

An opening 25 is provided in the slime fastening device 1.
Insert the drill pipe 21 having a bit at the tip. At this time, the pressurizing chamber 22 is formed between the packings 5 and 6 by the outer peripheral surface of the excavation pipe 21. A slime reservoir chamber 23 is formed next to the packing 5 on the guide casing 3 side. In this state, the excavation pipe 21 excavates.
The water in the storage tank 19 communicates with the water in the pressurizing chamber 22, and gives the water in the pressurizing chamber 22 a pressure generated by the difference in height between the ground and the height of the drilled hole. The ground around the drilled hole 17 also has a high pressure due to the difference in height from the ground and tends to jet toward the outlet of the drilled hole 17, but the pressure in the pressurizing chamber 22 also has the same pressure due to the same height difference. Therefore, they are balanced and held in the slime reservoir chamber 23. As a result, slime flowing between the packings 5 and 6 and the outer peripheral surface of the excavation pipe 21 is reduced, and wear of the packing due to sand is reduced. Further, since slime flowing out from the drilled hole 17 is extremely reduced, there is no fear of ground subsidence.

When the excavation is interrupted on the way, the adjusting valve 9 is slightly opened to discharge the slime in the slime reservoir chamber 23 little by little. This prevents the slime in the drilled hole 17 from flowing little by little, sticking the earth and sand around the excavation pipe 21, and preventing the excavation pipe 21 from moving. Drilling pipe 2 during excavation
When pulling out 1, the plate member 24 whose tip is formed in an arc shape in the slit 13 of the slime fastening portion 2 immediately after pulling out
Insert. The tip peripheral edge of the plate member 24 is fitted into the groove 14 on the inner periphery, and the plate member 24 allows the opening 25 of the slime fastening device 1 to be opened.
Close up. The outflow of earth and sand from the drilled holes 17 is stopped, and ground subsidence does not occur.

[0015]

The present invention has the above-mentioned structure and can obtain the following effects. A pressure chamber communicating with a reservoir on the ground was provided in the slime fastening device, and the pressure generated by the difference in height from the ground was applied to the water in the pressure chamber, so that the pressure that would always spray into the drilling hole was Balance. As a result, excavated soil is prevented from flowing out from the drilled hole, so that ground subsidence does not occur. The pressure in the pressurizing chamber is supplied by supplying water from the ground to pressurize by utilizing the difference in height, and a device such as a compressor is not required, and the construction is easy and the device is inexpensive. Since the slime is stopped before the pressurizing chamber, sand is less likely to be caught between the packing and the excavation pipe, wear of the packing is reduced, and durability of the slime fastening device is increased. When pulling out the excavation pipe, if you insert the plate material from the side slit immediately after pulling out, the plate material will fit into the groove continuous with the slit and block the opening of the slime fastening device, stopping the slime that is about to spout You can It is possible to prevent the sediment from sticking to the outer circumference of the drill pipe by adjusting the outlet adjustment valve to allow the slime outside the drill pipe to flow little by little.

[Brief description of drawings]

FIG. 1 is an overall view of an implementation of a drilling method according to the present invention.

FIG. 2 is a half cutaway view of a slime fastening device.

FIG. 3 is a partial perspective view of a slime fastening device.

[Explanation of symbols]

 1 Slime fastening device 2 Packer part 3 Guide casing part 4 Tag part 5 Packing 6 Packing 7 Water supply port 8 Discharge port 9 Control valve 10 Tag part 11 Shutter frame plate 12 Holding plate 13 Slit 14 Groove 15 Underground continuous wall 16 Sand ground 17 Machining Hole 18 Band 19 Tank 20 Hose 21 Drilling pipe 22 Pressurizing chamber 23 Slime pool chamber 24 Plate 25 Opening

Claims (3)

[Claims] 1. A tubular guide casing portion and a tubular packer portion that communicates with the guide casing portion and has a packing projecting like an inner flange at two locations spaced apart by a predetermined distance in the longitudinal direction of the tubular body. The slime fastening device, which has been made into a form, is inserted into the drilling hole where the guide casing portion is drilled at a position lower than the ground, the packer portion is projected from the ground, and the excavation pipe is inserted into the slime fastening device to be excavated. The space inside the slime fastening device surrounded by the packing and the outer peripheral surface of the drilling pipe is used as a pressurizing chamber, and water on the ground is supplied to the pressurizing chamber to generate the pressure generated by the difference in height between the ground and the drilling hole. A method for drilling holes in soft ground, which is characterized in that: 2. A tubular guide casing portion and a tubular packer portion which communicates with the guide casing portion and which has a packing projecting like an inner flange at two locations spaced apart by a predetermined distance in the longitudinal direction of the tubular body. The space surrounded by the outer peripheral surface of the excavated pipe inserted inside and the two packings is made into a pressurizing chamber, and this pressurizing chamber and the reservoir on the ground are connected by a hose, and the guide casing part of the packing is connected. A slime fastening device characterized in that a discharge port with a regulating valve capable of discharging excavated earth and sand to the outside is provided on the packing closer to the guide casing and further to the guide casing. 3. A groove is formed around a circular opening on the opening side of the packer part, a slit continuous to this groove is opened on the side of the sand packer part, and a plate material is inserted from this slit, The slime fastening device according to claim 2, wherein the opening of the packer portion can be closed.