JP2001193050A - Ground improvement method directly underneath large- scaled structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground improvement method directly underneath a large- scaled structure. SOLUTION: Boring is started downward at a slant toward the structure from the neighborhood of the large-scaled structure by using a non-cut and cover type boring machine equipped with a flexible joint rod having a drill head on the front end, the propulsive direction of the drill head is turned to horizontal at a specific site, and then, the direction is changed upward at a slant to bore a hole in the ground to the ground surface as the pilot hole, the drill head is changed into a back reamer, the pilot hole is reamed toward the boring machine to form the permanent hole, at the same time, a packer loaded chemical grouting pipe and an external pipe storing the packer loaded chemical grouting pipe thereinto are pulled into the permanent hole, the external pipe is pulled out to leave the packer loaded chemical grouting pipe in the permanent hole for grouting chemicals, those operations are repeated to infiltrate the chemicals into the whole improvement objective area, and the chemicals are solidified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for improving a ground by injecting a chemical solution, infiltrating and solidifying the same, and more particularly to a method for improving a ground immediately below an existing large building.

[0002]

2. Description of the Related Art When improving the safety of a building by improving the ground immediately below the existing building, if the target building is small, vertical and diagonal boring is performed from the periphery of the building to form it. The construction can be performed by inserting a chemical injection pipe into the drilled hole and injecting it into the ground to allow the chemical to permeate and solidify. However, when the target building is large, it is not possible to infiltrate the chemical solution just below the center of the building by using the inclined injection method, and therefore, the vertical and inclined injection methods must be applied to the periphery of the large building. In order to improve the ground immediately below the building, a vertical shaft was first constructed near the periphery of the building, horizontal boring was performed from the side wall of the vertical shaft, and then a chemical injection pipe was inserted into the drilled hole. An open-cutting method has been implemented in which a chemical solution is inserted into the ground by inserting a liquid.

[0003]

The conventional open-cutting method in which the chemical solution is horizontally injected from the side wall of the shaft requires the construction of several large shafts around the building,
Therefore, the construction cost of the shaft is enormous, and drilling for arranging the chemical injection pipe with a normal boring machine is impossible except for straight-line construction. There is a problem in that the intended ground improvement cannot be performed if there is an obstacle on the axis of the borehole.
Further, the drilling distance by a normal horizontal boring machine is limited to about 50 m in view of the accuracy of the formed bore.

Accordingly, a main object of the present invention is to provide a method of improving the ground immediately below a large building, which does not require the construction of a deep shaft, and therefore provides a cost-effective method.

An additional, but important, object of the present invention is to enable drilling while avoiding obstacles on the axis of the intended drilling in the ground area to be improved. Accordingly, it is an object of the present invention to provide a ground improvement method which has a considerable degree of freedom in the direction of a drilled hole to be formed and can set an efficient drilling pitch.

Another object of the present invention is to provide an improved method of ground, which can greatly extend the drilling distance than before.

[0007]

According to the present invention, there is provided:
The problem described above is to start drilling from near a large building and diagonally downward toward the structure using a non-cutting boring machine equipped with a flexible connecting rod with a drill head at the tip. When the tip of the drill head reaches a predetermined depth, the direction of the propulsion is turned horizontally to continue drilling, and then the direction of the propulsion of the drill head is turned obliquely upward to the surface of the earth. A pilot hole is formed by drilling, and the drill head of the boring machine is replaced with a back reamer, while a packer is mounted, and a large number of pieces are provided in a length portion having flexibility and corresponding to the ground area to be improved. Inserting a drug solution injection tube in which pores are drilled into a flexible outer tube, connecting at least one free end of the outer tube and the drug solution injection tube with the back reamer, Pie with lubricant The main hole is gradually formed by secondary drilling by the back reamer while spraying the inner side wall of the pilot hole from the outlet side of the pilot hole toward the boring machine and expanding the hole diameter of the pilot hole. As the process proceeds, the above-mentioned chemical liquid injection tube housing outer tube is pulled into the main hole, and the connecting rods gradually pulled back in the pilot hole toward the boring machine main body are individually collected on the boring machine main body side, When the tip of the outer tube reaches the entrance of the pilot hole, remove and collect the back reamer from the tip of the rod, pull out the outer tube and leave the packer-attached drug solution injection tube in the main hole. Then, the chemical is injected into the chemical injection pipe to inject and penetrate the chemical into the ground, and then the boring machine is moved to perform the drilling operation of the pilot hole and the boring. By repeating the operation of forming the main hole by the creamer and the operation of drawing in the main hole of the chemical liquid injection tube housing outer tube, the operation of pulling the outer tube, and the operation of injecting the chemical solution, the chemical solution penetrates the entire ground area to be improved, and the chemical solution The above object is achieved while solving the problem by a method of improving the ground immediately below a large building, which is characterized by being solidified.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A non-cutting boring machine used for drilling pilot holes in the method according to the present invention includes FlowMol, Corby, Northamptonshire, England.
e Ltd. and UTI in South Kent, Washington, USA
An example is a boring machine commercially available from LX Corporation. The drill head attached to the tip of the flexible rod in this boring machine was drilled linearly when propelled while rotating, and was cut diagonally at the tip of the drill head when propelled without rotating. The direction is changed by receiving earth pressure on the surface. This drill head has a built-in transmitter, so the position of the drill head can be constantly monitored,
Even when there is an obstacle on the axis of the intended drilling in the ground area to be improved, it is possible to drill while avoiding the obstacle.

According to the method of the present invention, a pilot hole is first drilled by a drill head while avoiding an obstacle possibly existing in the ground to be improved, and the drill head is replaced with a back reamer at an outlet side of the pilot hole. Since the back reamer is guided into the pilot hole and the hole diameter of the pilot hole is increased to form the main hole, the outer tube for accommodating the drug solution injection tube is drawn into the main hole. The degree of freedom in construction is significantly improved compared to the case of using a drilling machine, and the drilling accuracy is improved by detecting the position of the drill head outside the structure. It can be extended more than twice as much as when used, that is, up to more than 100m.

In a non-cutting ground improvement method for drilling a ground in a vertical or oblique direction, inserting a chemical injection pipe into a formed hole, injecting a chemical into the ground, and penetrating into the ground, and solidifying, Normal water is used as a lubricant at the time of drilling, and a vertical shaft is constructed and drilled by horizontal boring from the side wall of the vertical shaft, a chemical solution injection pipe is inserted into the formed hole, and a chemical solution is pressed into the ground by pressing. In the method for improving the ground excavation to be infiltrated and solidified, bentonite-based lubricating materials are used at the time of drilling.

However, a pilot hole is formed by a drill head, and then the main hole is formed by expanding the diameter of the pilot hole by a back reamer. When the method of the present invention is carried out, water or bentonite is used as a lubricant. A mud film is formed on the peripheral wall of the main hole, and the mud film may hinder the penetration of the chemical solution into the ground when the chemical solution is injected into the ground later.

Therefore, when the method according to the present invention is carried out, a lubricant such as a highly water-absorbing polymer is used when drilling the holes. Examples of superabsorbent polymers include starch-based, cellulose-based, other polysaccharide-based (eg, hyaluronic acid-based) and protein-based natural high-molecular polymers, and polyvinyl alcohol-based, acrylic-based, and other additional polymers.
(For example, maleic anhydride polymer), polyether,
Although there are synthetic polymer polymers such as condensation polymers (e.g., ester polymers), natural polymer is not preferable because the crushing strength of the water-absorbing gel is low considering the penetration of the drug solution into the ground. Therefore, a synthetic high molecular polymer is preferable, and it is advantageous to use an acrylic acid-based or maleic anhydride-based polymer in consideration of use safety and the like.

The above lubricant can be used when drilling a pilot hole. The pilot hole diameter is about 5
It is 0 mm, and drilling is basically performed in the form of no earth removal.
In other words, the drilling is performed in a compacting manner while pushing the earth and sand by pushing the drill head. When a pilot hole is drilled using a lubricant, a small amount of the lubricant containing mud flows along the rod and flows out to the boring machine body side.
The hole diameter of the main hole formed by the back reamer is about 100 mm
Therefore, the drilling is basically performed in a non-discharged manner like the pilot hole. In forming this main hole, a lubricant is used as described above, so that a small amount of mud containing lubricant travels along the rod to the boring machine body side, and also travels along the outer pipe to an outlet of the pilot hole. Come out to.

[0014] The chemical liquid injection pipe used when the method of the present invention is carried out and having a perforated hole at an appropriate position, and an outer pipe for accommodating the chemical liquid injection pipe are made of synthetic resin, for example, vinyl chloride resin. And these tubes have a minimum radius of curvature for drilling
If it has the flexibility to follow 30m, there is no problem in construction. A plurality of packers mounted at appropriate locations on the chemical injection tube and housed in the outer tube together with the chemical injection tube may be made of cloth, and the mounting position of the packer moves when the outer tube is later pulled out. It is applied to the chemical injection tube so that it does not. The outer tube protects the chemical solution injection tube and the packer until the chemical solution injection tube and the packer are pulled out and remains in the main hole formed in the ground, and the chemical solution injection hole of the chemical solution injection tube is covered with earth and sand. It serves to prevent clogging.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the method according to the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a pilot hole drilling step, which is a first step of a ground improvement method immediately below a large building according to the present invention. In the figure, reference numeral 10 denotes a target large building, reference numeral 12 denotes a ground, and reference numeral 122 denotes a ground area to be improved. In order to inject the chemical and infiltrate the ground area 122 to be improved and to improve the ground by solidifying the chemical, thereby improving the safety of the structure, first, a pilot hole is drilled near the building 10. While drilling a small shaft 14 for opening a hole, a boring machine 20 is fitted with a flexible rod 22 made of synthetic resin, for example, vinyl chloride resin, and a drill head 24 is attached to the free end of the rod. The drill head is set in the shaft 14 so that the tip is directed obliquely below the structure, and drilling of the pilot hole is started. The formation of the pilot hole is performed in a non-discharged manner, and the drilling of the pilot hole is continued by the propulsion of the drill head while adding and connecting the rods. Figure 1 shows that the drill head 24 diagonally penetrated into the ground 12 via the shaft 14, and
Reaches the improvement target ground area 122 below one end of the building, further straightly moves diagonally downward, then turns horizontally in the improvement target ground area and goes straight ahead, so that the pilot hole reaches just below the other end of the building 10. 126 is shown drilled. Thereafter, the drill head turns obliquely upward and reaches the surface 124, thereby completing the drilling of the pilot hole. The diameter of the pilot hole thus formed is about 5 cm.

FIG. 2 shows a tip portion of the drill head 24. The drill head is drilled linearly when propelling while rotating, and is obliquely cut when propelling while stopping rotation. On the surface 242, the direction changes under the earth pressure. The direction of the propulsion of the drill head forming the pilot hole 16 is determined by the worker receiving the signal from the transmitter built in the drill head on the boring machine side and constantly monitoring the current position of the drill head. Will be modified accordingly. Since the extended rod 22 has the flexibility to follow the minimum radius of curvature 30 m of the pilot hole, the distance from the entrance to the exit of the pilot hole formed by the propulsion of the drill head 24 is up and down. It is possible to cope with the case of changing in the left-right direction. Therefore, when there is an obstacle on the drilling axis of the pilot hole, the propulsion of the drill head is performed so as to avoid the obstacle and drill the pilot hole. The operator can operate to correct the direction of the work. Further, when drilling a pilot hole, a lubricant is prepared by adding and mixing a lubricant, for example, an acrylic or maleic anhydride polymer, which is a superabsorbent polymer in powder, spherical or crushed form, with water from a drill head. Can be injected from a drill head, thereby improving drilling efficiency.

If the distal end of the flexible rod 22 connected to the rear end of the drill head 24 emerges from the outlet of the pilot hole 16, the drill head is removed and collected, and the rod 22 is replaced with the same. A back reamer described later is attached to the free end.

FIG. 3 shows a chemical injection pipe 30. The chemical injection pipe is used to inject a chemical into the ground at a site corresponding to the ground area 122 to be improved and to penetrate the ground area to be improved. A large number of pores 302 are formed, and a packer 32 is intermittently mounted so that the chemical solution is uniformly pressed in the ground area to be improved. This packer can be made of cloth. The distal end portion 304 of the chemical injection tube has no pore, its free end is closed, and a mounting ring 306 is formed at the end. The chemical injection tube 30 equipped with the above packer 32 is
It is housed in an outer tube described later for protecting the packer. Both the outer tube and the chemical injection tube are made of a synthetic resin such as a vinyl chloride resin, and have a flexibility capable of following a minimum radius of curvature of 30 m.

In FIG. 4, the mounting ring 306 (see FIG. 3) of the chemical solution injection pipe 30 on which the packer 32 is mounted and the rear end of the back reamer 26 are connected by a cable 34, and the lubricant is boring from the lubricant supply vehicle 40. To the back reamer 26 via the connected rod 22 and operate the boring machine 20 to rotate the back reamer and to form the lubricant from the peripheral wall of the back reamer. The rod is pulled toward the boring machine side while spraying from the pilot hole exit to the peripheral wall of the pilot hole, and the pilot hole is enlarged to form the main hole.
Is gradually drawn into the main hole 18 via the cable 34 and together with the outer tube 40 accommodating the packer-mounted chemical injection tube. An embodiment is shown. The hole diameter of the main hole is about 100 mm.
The formation of 18 is performed in the same manner as the drilling of the pilot hole 16 by the drill head 24 (see FIG. 2) in the form of no earth removal.
The lubricant used in forming the main holes is the same as that described above.

The connected rods 22 are made into individual rods and collected as they are drawn toward the boring machine side.
The rotation of the back reamer is stopped when the back reamer reaches the shaft, and the back reamer is stopped when the tip of the outer tube 40 containing the drug solution injection tube with the packer reaches the shaft. Is removed and collected, and the outer tube is pulled out. In this case, the packer-fitted drug solution injection tube housed in the outer tube (see FIG. 3)
Is left in the main hole 18 in the ground 12.

Next, a chemical solution preparation device is connected to the chemical solution injection pipe 30.
(Not shown), a chemical solution (not shown) is press-fitted, and the chemical solution is injected into a pore 302 (see FIG. 3) formed in the chemical injection tube.
A predetermined amount is injected into the ground 12 through the
22 and gradually solidifies to improve part of the ground directly below the large building 10. As the above-mentioned chemical solution, a general-purpose chemical solution used for improvement of the ground by injection, penetration, and solidification into the ground can be used.For example, ultrafine silica sol grout can be used, and uniaxial compression when the grout hardens. The intensity q is set to about 100kPa. After injecting the chemical solution into the chemical injection tube, the entrance of the main hole 18
A small excavation is performed in the vicinity and around the chemical injection pipe 30, the chemical injection pipe is cut below the ground surface, the excavation part and the shaft on the boring machine side 14 are backfilled, and the chemical injection pipe with the packer is It will be in a state of being embedded inside.

Thereafter, the position of the boring machine is moved to perform the various operations described above, that is, the operation of drilling a pilot hole, the operation of forming a main hole, the operation of pulling the outer tube containing the chemical solution injection tube into the main hole, the operation of the outer tube. A pull-out operation, a liquid injection operation, a cutting operation of the liquid injection pipe, and a backfill operation of the excavation part and the shaft are performed. The above operations, including the movement of the boring machine, are repeatedly performed, whereby the improvement can be performed over the entire ground area to be improved immediately below the large building.

[0023]

The method of the present invention is a non-cutting method,
Therefore, it is not necessary to construct a large shaft which is expensive, and the drill head is capable of constantly monitoring the position and correcting the direction of propulsion, and a flexible connection connected to the drill head. Pilot holes are drilled using a boring machine equipped with a rod, and the drill head is replaced with a back reamer at the outlet side of the pilot holes, in the direction opposite to the direction in which the pilot holes were drilled, and the diameter of the pilot holes. Is expanded by the back reamer to form a main hole, and a flexible outer tube containing the packer-mounted flexible drug solution injection tube is drawn into the main hole, and the outer tube is formed. After the leading end of the cartridge reaches the inlet of the pilot hole formed earlier, the outer tube is pulled out to leave the above-mentioned packer-attached drug solution injection tube in the main hole, and then the drug solution is passed through the drug solution tube with a packer. That by injecting the chemical into the soil to be solidified impregnated with drug solution to an improved target ground area by press-fitting is intended to be basic, it is possible to rationally improved soil immediately below the large buildings. According to the method of the present invention, it is possible to drill a pilot hole in which the direction of the hole path changes vertically and horizontally, so that the pilot hole can be formed while avoiding an obstacle that may be present in the ground to be improved. And since the main hole in which the chemical solution injection pipe is to be arranged is formed by expanding the diameter of the pilot hole, the degree of freedom of construction is significantly increased and the drilling accuracy is high when compared with the conventional open-cutting method. In addition, the drilling distance of the main hole can be greatly extended. Since a superabsorbent polymer-based lubricant is used in drilling without using a bentonite-based lubricant as in the past, the penetration of the chemical solution into the ground is not hindered, and therefore, the drilling is performed over the entire ground area to be improved. It is possible to improve the period.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a drilling mode of a pilot hole in a method according to the present invention.

FIG. 2 is a perspective view showing a distal end portion of a drill head used for drilling a pilot hole.

FIG. 3 is a partially cutaway plan view showing a packer-fitted chemical injection tube used in the method according to the present invention.

FIG. 4 is a schematic view showing a mode of drilling a main hole and a mode of drawing an outer tube containing a packer-fitted chemical liquid injection tube into the main hole in the method according to the present invention.

[Explanation of symbols]

 10: Large building 12: Ground 122: Ground area to be improved 124: Ground 14: Shaft 16: Pilot hole 18: Main hole 20: Boring machine 22: Rod (for connection) Rod 24: Drill head 242: (Drill head ) Diagonally cut surface 26: Back reamer 30: Chemical injection tube 302: Pores 304: Tip of (chemical injection tube) 306: (For mounting) Ring 32: Packer 34: Cable 40: Lubricant supply vehicle 50: Outer tube

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Koketsu 2- 2-8 Koraku Goyo Construction Co., Ltd. (72) Inventor Hidefumi Ishizawa 2-2-8 Koraku 2 Bunkyo-ku Tokyo Metropolitan Goyo Construction (72) Inventor Yuki Hosokawa 2-8-8 Koraku Bunkyo-ku, Tokyo Goyo Construction Co., Ltd. F-term (reference) 2D029 DA02 2D040 AB01 BB03 BC01 CA10 CB03 DA03 DA05 DA11 DB00 DC02 FA01

Claims (3)

[Claims] 1. Using a non-cutting boring machine equipped with a flexible connecting rod having a drill head at the tip, drilling starts from near a large building and obliquely downward toward the structure. When the tip of the drill head reaches a predetermined depth, the direction of the propulsion is turned horizontally to continue drilling, and then the direction of the propulsion of the drill head is turned obliquely upward to reach the ground surface. The pilot hole is formed by drilling, and the drill head of the boring machine is replaced with a back reamer, while a packer is mounted, and a large number of length portions having flexibility and corresponding to the ground area to be improved are provided. Inserting a drug solution injection tube having a perforated hole into a flexible outer tube, connecting at least one free end of the outer tube and the drug solution injection tube with the back reamer, and using the back reamer as a lubricant The pyro The main hole is gradually formed by secondary drilling by the back reamer while spraying the inner side wall of the pilot hole from the outlet side of the pilot hole toward the boring machine and expanding the hole diameter of the pilot hole. As the process proceeds, the above-mentioned chemical liquid injection tube housing outer tube is pulled into the main hole, and the connecting rods gradually pulled back in the pilot hole toward the boring machine main body are individually collected on the boring machine main body side, When the tip of the outer tube reaches the entrance of the pilot hole, remove and collect the back reamer from the tip of the rod, pull out the outer tube and leave the packer-attached drug solution injection tube in the main hole. Then, the chemical is injected into the chemical injection pipe to inject and penetrate the chemical into the ground, and then the boring machine is moved to drill the pilot hole and perform the boring operation. By repeatedly performing the operation of forming the main hole by the reamer and the operation of drawing in the main hole of the chemical liquid injection tube housing outer tube, the operation of pulling the outer tube, and the operation of injecting the chemical solution, the chemical solution penetrates the entire area of the ground to be improved, and the chemical solution is diffused. A method of improving the ground directly under a large building, characterized by solidification. 2. The method for improving ground immediately below a large building according to claim 1, wherein a superabsorbent polymer-based lubricant is used during drilling. 3. The method for improving ground immediately below a large building according to claim 1, wherein a chemical solution containing ultrafine silica particles is used.