JP4878294B2 - Ground improvement method and equipment - Google Patents

Description

  The present invention relates to a ground improvement method and an apparatus thereof that are optimal for places where it is difficult to excavate directly from the ground surface, such as the lower part of a structure.

For example, when the lower ground of a structure such as a large tank is soft and may be liquefied, and improvement is desired, conventionally, as described in Patent Document 1, one or two places are provided outside the structure. In other words, a vertical shaft was installed, and horizontal drilling was taken from here.
However, in recent years, an excavation head capable of freely controlling the traveling direction has been developed in the United States, and by using this, it has become possible to lay a pipe line in an arbitrary shape including a bent portion without providing a shaft. In the present specification, this method is hereinafter referred to as “free boring”. Patent Document 2 describes such a digging apparatus and a free boring method using the same.

  FIG. 5 is a cross-sectional view of an embodiment of the excavation head 2 described in Patent Document 2, wherein 21 is a pressure water injection nozzle, and 22 is a pressure water path through which pressure water is supplied. The pressure water jet nozzle 21 is directed obliquely about 5 degrees with respect to the digging head 2. Accordingly, if the digging head 2 is moved forward while being rotated, it proceeds in the linear direction (head direction).

  FIG. 6 is an external view of the excavator 4 similarly described in Patent Document 2, wherein 40 is a base, 41 is a forward frame that moves on the base, 42 is a rotation motor, 43 is a chain, 44 is a forward motor, 3 Is a digging rod for advancing the digging head, and the advancing frame 41 is provided with a clamp for fixing the distal end portion of the digging rod 3 and a chuck for gripping and rotating the distal end portion of the digging rod 3. When combined, the excavation rod 3 can be advanced without rotating, or can be advanced while rotating. If the forward motor 44 is reversely rotated, it can be pulled out. The excavation rod 3 is a flexible and hollow tube body such as a steel pipe.

Patent Document 2 also describes that the current position of the digging head can be detected by a ground receiver by equipping the digging head 2 with a position sensor, a wireless transmitter, and a directional antenna. The detection of the current inclination of the head 2 is described as incorporating an electrolytic transducer.
FIG. 7 is a conceptual diagram in the case where the ground improvement of the lower part of the structure S is performed using such a boring device. Boring is started obliquely from the ground next to the structure S and reaches a predetermined depth. Then, the direction of the digging head 2 is changed to the horizontal direction, and thereafter the horizontal boring is performed. Every time the excavation rod 3 moves forward by the unit length, new excavation rods 3 are successively connected to the end of the excavation rod 3. A portion Z surrounded by a broken line is an area to be ground improved.

Patent Document 3 discloses a step of drilling a predetermined area using such a boring device, a step of injecting a filler such as sand from the tip of the boring rod, and boring by pulling the boring rod by a predetermined distance. A filling grout method having a step of injecting a filler from a rod tip is described. Hereinafter, this is referred to as a “single pushing method”.
In Patent Document 4, a drilling head described in Patent Document 2 is used, and in the first step, a drill head is formed in the ground directly under the structure to form a pilot hole up to the ground surface on the opposite side, and then a drill is drilled. It is described that the pilot hole is expanded by replacing the head with a back reamer and pulled back to the starting side, and the chemical solution injection pipe is drawn into the expanded main hole to improve the ground. Hereinafter, this is referred to as “retraction method”.

Further, in Patent Document 5, a pressure water injection nozzle for digging and a water supply hose connected to the digging head of a universal boring device are attached, and a discharge port for injecting a chemical solution and an injection for connection connected thereto. The hose is attached at the same time, and mixing of the pressure water and the chemical solution is prevented by using a check valve.
JP-A-2005-270786 JP-A 61-257501 Japanese Patent Laid-Open No. 2003-3459 JP 2001-193050 A JP-A-2005-76177

In the horizontal boring by a shaft described in Patent Document 1, it is necessary to construct at least two shafts, which is expensive and time consuming, and is extremely uneconomical. Also, the path cannot be arbitrarily bent. A large amount of soil is also generated.
The one-pushing method described in Patent Document 3 requires at least two steps of rod drilling and rod extraction while injecting filler.

The pull-in method described in Patent Document 4 requires at least three steps of pilot hole formation, diameter expansion by a back reamer, and pulling of a chemical injection pipe, and the ground surface on the opposite side in the formation of the pilot hole in the first step. The construction distance is large and at least two work yards are required.
Further, according to the invention described in Patent Document 5, although advantages such as the need for operations such as insertion of a head and connection of piping for each process switching between excavation and chemical injection are recognized, Each time the rod is connected, the pressure water hose for excavation and the hose for chemical injection must be added, and the joint structure corresponding to the twist of the hose when excavating while rotating the excavation head is not explained In addition, not only is it difficult to implement, but it is not realistic because the excavator must remain in the field even if the excavation is completed and the injection stage is completed.

  The present invention eliminates these problems in the prior art, and provides a ground improvement method and apparatus capable of reliably switching between injection of pressure water and injection of chemical liquid in a small number of steps and during excavation. It aims at realizing.

  The present invention according to claim 1 is a digging head having a pressure water jet nozzle inclined at an angle with respect to the shaft at the tip, and sequentially connected to the rear of the digging head to advance and retreat and rotate the digging head. By means of a flexible boring device for ground improvement comprising a flexible hollow excavation rod, an excavator that advances and retreats and rotates a distal end portion of the excavation rod, and a chemical injection head that is inserted into the excavation rod. Boring in an oblique direction from the ground while jetting pressure water from a pressure water jet nozzle, boring in a horizontal direction from a predetermined position to reach the digging head to a target position, and then placing a chemical injection head in the digging rod Inserting and closing the inner space of the head for the pressure water injection nozzle for digging, simultaneously opening the chemical injection hole and retreating the digging head, It is a ground improvement method characterized by pulling out the digging head together with the digging rod while injecting the chemical into the ground from the side of the digging head at the retreat start position and each receding position or from the side of the digging rod immediately after connecting to the digging head is there.

The present invention according to claim 2 is the ground improvement method according to claim 1, wherein at least a part of the chemical solution to be injected into the ground is a two-component mixed curing agent.
According to a third aspect of the present invention, there is provided an excavation head, a flexible hollow excavation rod that is sequentially connected to the rear of the excavation head and moves the excavation head forward and backward, and rotates, and an end portion of the excavation rod. A universal boring device for ground improvement comprising an excavating machine that moves forward and backward and rotates, and a chemical injection head that is inserted into the excavating rod, wherein the excavating head has pressure water inclined at an angle with respect to an axis at a tip portion. A first injection means having an injection nozzle and having a chemical injection hole on a side of the digging head or a side of the digging rod immediately after being connected to the digging head, and closing the chemical injection hole during digging; It is a universal boring apparatus for ground improvement, characterized in that it is provided with a second closing means for closing the inner space of the excavation head toward the pressure water injection nozzle.

A fourth aspect of the present invention is the universal boring apparatus for ground improvement according to the third aspect, wherein the first closing means is a resin plug inserted into the chemical injection hole.
The present invention described in claim 5 is the universal boring apparatus for ground improvement according to claim 3, wherein the first closing means is a magnet sheet attached to the inner surface of the chemical injection hole.
According to a sixth aspect of the present invention, the chemical injection head includes a pressing member that eliminates the first closing means at the tip, and a packer that is inflated by pressurized air that is the second closing means at the rear thereof. 4. The universal boring apparatus for ground improvement according to claim 3.

  The present invention described in claim 7 is the universal boring apparatus for ground improvement according to any one of claims 3 to 6, wherein the chemical injection head is connected to a plurality of chemical injection pipes. .

  According to the present invention, there is no need to replace the drill head or increase the diameter of the drill head as in the “single pushing method” or the “retraction method”, and it is not necessary to form a pilot hole up to the ground surface on the opposite side, and the pressure during excavation There is an excellent effect of realizing a ground improvement method capable of reliably switching between water injection and chemical injection.

Embodiments of the present invention will be described with reference to the drawings.
The universal boring apparatus used in the present invention includes an excavation head having a pressure water jet nozzle obliquely oriented with respect to the shaft at the tip, and sequentially connected to the rear of the excavation head so that the excavation head can be moved forward and backward and rotated. It comprises a flexible hollow excavation rod, an excavator that advances and retreats and rotates the end portion of the excavation rod, and a chemical injection head that is inserted into the excavation rod. The excavator is not different from the previously known ones except for those immediately after connecting to the head).

  In the present invention, by such a boring device for ground improvement, the pressure head is bored obliquely from the ground while jetting pressure water from the pressure water jet nozzle, and the excavation head is drilled horizontally from a predetermined position. Reach the target position. Since the excavation rod is hollow, if pressure water is supplied into the pipe from the position of the end excavator, the pressure water is ejected from the pressure water injection nozzle 21 of the excavation head 2 as shown in FIG. Is done. As will be described later, in this state, since the chemical injection hole 31 provided in the immediately following excavation rod 3a is blocked, no pressure water is ejected from here. The position of the digging head during digging may be detected by inserting a known position sensor or the like up to the position of the digging head in the pipe. After digging to the target position as shown in FIG. 7, the chemical injection head is inserted into the digging rod, and the internal space to the pressure water injection nozzle 21 at the tip of the digging head 2 is closed by the second closing means described later. Excluding the first closing means, the chemical solution injection hole 31 is opened, and the chemical solution injection provided on the side surface of the digging head 2 or the side surface of the digging rod 3a just after connecting to the digging head as shown in FIG. A chemical solution is injected from the hole 31 into the ground. As shown in FIG. 3, an air pipe 73 and chemical liquid injection pipes 74 and 75 are connected to the chemical liquid injection head 7. However, in the present invention, these insertions are performed after the end of the excavation process. It is not necessary to add little by little at the excavation stage as in the invention, and the work is easy.

The excavation head 2 is retracted while injecting the chemical solution, and the excavation head 2 is pulled out together with the excavation rod 3 while injecting the chemical solution at each retracted position to improve the ground, thereby completing the operation. In order to retract the digging head, it is not always necessary to use a digging machine, and it can be easily performed by pulling out the digging rod with a winch or the like.
Here, it is convenient to provide two chemical solution injection tubes so that two types of chemical solutions to be injected can be used. For example, in the case of a two-component mixed type curing agent that reacts and cures by mixing, the tube will not be clogged if it is not mixed until just before the injection hole. Moreover, construction becomes easy by using properly the A liquid which is a slow-binding agent and the B liquid which is a quick-binding agent. First, injecting a caking agent into the gap between the drilled ground and the excavation head to close this gap, and then injecting the caking agent, the caking agent does not leak to the surroundings, and the efficiency is improved. Good injection is possible. As the slow-binding agent, for example, sodium silicate (water glass) is used, and as an example of the flash-setting agent, a certain type of catalyst is used.

  Subsequently, the first closing means for blocking the chemical injection hole during the excavation, and the second closing means for closing the internal space of the excavation head for the pressure water injection nozzle during the chemical injection, that is, the ejection hole and the chemical injection hole The opening / closing mechanism will be described. FIG. 2 is a partial cross-sectional view showing the vicinity of the chemical liquid injection hole 31 of the embodiment. 3a is a digging rod immediately after the digging head 2, 5 is a joint, and a general digging rod 3 is sequentially connected to the rear via this. The

  A plurality of chemical solution injection holes 31 are provided on the entire circumference of the rear side surface of the digging rod 3a, and resin bolts 61 serving as first closing means are inserted into the holes and fastened with nuts 62 to be fixed. The injection hole 31 is blocked. Therefore, high-pressure water does not leak from the chemical injection hole 31 during the excavation work. It is desirable to insert a seal member such as an O-ring under the neck of the resin bolt 61 as appropriate. Further, a protective cover ring 63 is fitted so that the resin bolt 61 is not damaged during the excavation. In this state, excavation is performed, and then a chemical injection head is inserted into the pipe.

  FIG. 3 is a partial cross-sectional view showing a state in which the inserted chemical liquid injection head 7 has reached the inside of the digging rod 3a immediately after the digging head. 71a and 71b are packers provided in two stages as second closing means, Reference numeral 72 is an opening, 73 is an air pipe for inflating the packers 71a and 71b, 74 and 75 are two chemical liquid injection pipes, and 76 is a pressing member attached to the tip of the chemical liquid injection head 7.

  The chemical injection head 7 has a hollow cylindrical shape, and its outer diameter is slightly smaller than the inner diameter of the digging rods 3 and 3a, and can move freely within the digging rod 3 when the packers 71a and 71b are contracted. Further, the pressing member 76 has a disk shape or a cup shape, and the outer periphery is substantially equal to the inner diameter of the digging rod 3. When the chemical injection head 7 is inserted into the digging rod 3 and the leading pressing member 76 passes the position of the chemical injection hole 31, the resin bolt 61 that becomes an obstacle is broken. The injection hole 31 is opened.

The resin bolt 61 is not necessarily a bolt but may be a simple stopper as long as it is fixed by covering the chemical solution injection hole 31 and broken as required.
On the other hand, when the chemical injection head 7 is inserted into the digging rod 3 and the drug injection hole 31 is positioned between the two stages of packers 71a and 71b, air is sent from the air pipe 73 to packers 71a and 71b. Is expanded, the inside of the chemical injection head 7 communicates with the chemical injection hole 31 through the opening 72 and is disconnected from the inside of the digging rod 3 outside the packers 71a and 71b. At the same time as the inner space of the digging head is closed, the chemical solution supplied from the chemical solution injection pipes 74 and 75 is injected into the surrounding ground from the chemical solution injection hole 31 without leaking out of the system.

  FIG. 4 is a partial sectional view of the vicinity of the chemical solution injection hole 31 showing another embodiment of the first closing means, and 64 is a magnet sheet, that is, a sheet-like magnetic rubber. When the digging rod 3a is made of a steel pipe, the chemical liquid injection hole 31 can be easily closed by attaching the magnet sheet 64 to the inner surface of the chemical liquid injection hole 31. And if the chemical | medical solution injection | pouring head 7 is allowed to pass, the magnet sheet 64 can be easily excluded and opened by the pressing member 76. The magnet sheet 64 may go around the inner surface of the tube, or may be divided for each chemical solution injection hole 31.

  If the excavation head is gradually retracted while injecting the chemical liquid, both the excavation rod and the chemical injection head can be collected. Since the excavation rod does not need to be rotated or pressed except at the initial excavation stage, the excavator can be removed and used for other construction.

It is a front view of the excavation head vicinity explaining the principal part of the ground improvement construction method of an Example of this invention. It is a fragmentary sectional view near the chemical solution injection hole for explaining the second closing means of the embodiment. It is a fragmentary sectional view which shows the vicinity of the digging rod immediately after the digging head explaining the 1st obstruction | occlusion means of an Example. It is a fragmentary sectional view near the chemical solution injection hole for explaining the second closing means of another embodiment. It is sectional drawing which shows the excavation head in a prior art. It is an external appearance perspective view which shows the excavation machine in a prior art. It is a conceptual diagram explaining the universal boring in a prior art.

Explanation of symbols

2 Digging head 3, 3a Digging rod 4 Digging machine 5 Joint 7 Chemical liquid injection head 21 Pressure water injection nozzle 22 Pressure water path 31 Chemical liquid injection hole 41 Advance frame 42 Motor for rotation 43 Chain 44 Motor for advance 61 Resin bolt (plug)
62 Nut 63 Covering 64 Magnet sheet 71a, 71b Packer 72 Opening 73 Air pipe 74, 75 Chemical solution injection pipe 76 Pressing member

Claims (7)

  An excavation head having a pressure water jet nozzle obliquely oriented with respect to the shaft at the tip, and a flexible and hollow excavation rod that is sequentially connected to the rear of the excavation head and advances and retreats and rotates the excavation head; Pressure water is jetted from the pressure water jet nozzle by a ground boring device for ground improvement consisting of an excavator for moving the distal end portion of the excavation rod forward and backward and rotating, and a chemical injection head inserted into the excavation rod. Boring in an oblique direction from the ground while boring in a horizontal direction from a predetermined position, the excavation head reaches the target position, and then a chemical liquid injection head is inserted into the excavation rod to inject pressure water for excavation. At the same time as filling the inner space of the head to the nozzle, the chemical injection hole is opened and the head is retracted. Side of the boring head in location or ground improvement method, characterized in that withdrawal of the boring head with boring rod while injecting the liquid medicine into the ground from the side of the excavation rod immediately after connecting to the boring head.   The ground improvement construction method according to claim 1, wherein at least a part of the chemical solution to be injected into the ground is a two-component mixed curing agent.   An excavation head (2), a flexible hollow excavation rod (3) which is sequentially connected to the rear of the excavation head (2) and moves the excavation head forward and backward and rotates, and an end of the excavation rod (3) A boring device for ground improvement comprising an excavator (4) for moving a part forward and backward and rotating and a chemical injection head (7) inserted into the excavation rod (3), wherein the excavation head (2 ) Has a pressure water injection nozzle (21) obliquely oriented with respect to the shaft at the tip, and a chemical solution injection hole (31) on the side surface of the digging head (2) or the side surface of the digging rod (3a) immediately after connecting to the digging head. And a second closing means for closing the inside space of the digging head for the pressure water injection nozzle (21) during the injection of the chemical liquid. To have prepared Universal boring device for ground improvement to symptoms.   The universal boring apparatus for ground improvement according to claim 3, wherein the first closing means is a resin stopper (6) to be inserted into the chemical injection hole.   The universal boring apparatus for ground improvement according to claim 3, wherein the first closing means is a magnetic sheet (64) attached to the inner surface of the chemical injection hole.   The chemical liquid injection head (7) includes a pressing member (76) that eliminates the first closing means at the tip, and packers (71a, 71b) that are inflated by pressurized air, which is the second closing means, behind the pressing member (76). The universal boring apparatus for ground improvement according to claim 3, which is provided.   The universal boring apparatus for ground improvement according to any one of claims 3 to 6, wherein the chemical injection head (7) is connected to a plurality of chemical injection pipes (74, 75).

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