JP2005042449A - Ground improvement method and excavating agitating head used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground improvement method superior in working efficiency while efficiently and sufficiently agitating and mixing the whole quantity of injected solidifying liquid with excavating sediment, and restraining a phenomenon of discharging the solidifying liquid injected into a drilled hole upward from an outer peripheral part of the excavating sediment. <P>SOLUTION: In this ground improvement construction method, the hole having the prescribed depth is drilled in the ground by the rotation of an excavating agitating rod by using the excavating agitating rod having an excavating blade, a solidifying liquid delivery port, and a freely advancing and retreating second agitating blade in a rod lower end part, and next, while rotating and extracting the excavating agitating rod, the solidifying liquid is injected into an extracted trace of the excavating agitating rod, and the injected solidifying liquid and the excavating sediment are agitated and mixed by the second agitating blade in the extracted trace. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ground improvement method by injecting a solidifying agent and an excavation stirring head of a stirring rod used for the ground improvement method.

  Conventionally, for example, a ground improvement method using a stirring rod in which a drilling head having a drilling blade and a solidified liquid discharge port at the lower end is connected to the lower end of the rod, and a large number of stirring blades project from the outer peripheral surface of the rod. First, the solidification liquid is injected at the time of drilling. The stirring rod is rotated, and the solidification liquid is injected into the hole from the discharge port while drilling into the ground by the excavating blade, and then the excavated sediment by the stirring blade. In this method, a large portion of the injected solidified liquid is discharged upward through the outer periphery of the excavated earth and the outer periphery of the rod, thereby solidifying. There was a drawback that most of the liquid could not be mixed with excavated sediment.

  In addition, a method of injecting solidified liquid when the stirring rod is pulled out to the ground after drilling has been performed, and in the type in which the solidified liquid is injected from the discharge port provided at the lowermost end of the excavating head, the excavating head is raised. Since the solidified liquid is injected into the trace, even if the phenomenon of discharging the solidified liquid upward can be suppressed, there is a difficulty that the solidified liquid and the excavated soil are hardly mixed with stirring. The laborious work of pulling out the stirring rod while moving it up and down repeatedly is necessary.

  On the other hand, in the type in which the solidification liquid is injected from the discharge port provided above the excavation blade in the excavation head at the time of pulling out after drilling, a part of the solidification liquid is discharged upward from the outer peripheral portion of the excavation earth and sand as described above. As a result, a large amount of solidifying liquid is injected, but the amount of solidifying agent consumed is large. In addition, since the solidified liquid does not reach the excavated soil below the discharge port, measures have been taken to take a drilling depth deeper than the predetermined depth required for ground improvement. The strength of the lower end of the solidified sand column was not sufficient, and not only the working time was lengthened, but also the economic disadvantage of having to increase the size of the machine used was incurred.

  The first invention of the present application is based on the phenomenon that the solidified liquid injected into the drilling hole is discharged upward from the outer peripheral portion of the excavated earth and sand, and the entire amount of the injected solidified liquid is thoroughly agitated and mixed with the excavated earth and sand without waste. The challenge is to provide a ground improvement method that is capable of working with good work efficiency,

  It is an object of the second invention of the present application to provide an excavation stirring head for a stirring rod that enables effective implementation of the first invention.

As means for achieving the above object, the first invention of the present application first employs a method of injecting a solidified liquid at the time of pulling out the stirring rod after drilling, and its configuration is
Using a drilling stirring rod having a drilling blade, a solidified liquid discharge port, and a second stirring blade capable of moving forward and backward at the lower end of the rod,
Drilling a predetermined depth in the ground by rotating the excavation stirring rod,
Next, while rotating and extracting the excavation stirring rod, the solidified liquid is injected into the extraction trace of the excavation stirring rod, and at the extraction trace, the injected solidified liquid and the excavation sediment are agitated and mixed by the second stirring blade. To go,
It is a ground improvement method,

The configuration of the second invention of this application is as follows:
In the drilling head having a drilling blade and a solid solution downward discharge port located below the drilling blade at the lower end of the head rod,
At the head rod lower end axial center position of the excavation head, an agitation rod having a second agitation blade at the lower end is inserted and supported so as to be movable forward and backward in the axial extension direction from the lower end surface of the head rod and non-rotatable.
Provided with drive means for advancing and retracting the stirring rod;
Drilling and stirring head.

  According to the ground improvement method of the first invention of the present application, since the solidification liquid is injected into the extraction trace of the excavation stirring rod when the excavation stirring rod is pulled out, the phenomenon of the solidification liquid being discharged upward can be suppressed, Since the agitation is immediately performed by the second agitating blade at the extraction trace, the total amount of the injected solidified liquid can be agitated and mixed with the excavated earth and sand, and the solidified liquid can be extracted after the excavated agitation rod is extracted. Therefore, it is possible to build a high-quality solid sand column in which the total amount of injection is mixed evenly, and it is possible to maintain a good work efficiency because it does not require the extra work found in the conventional method.

  Moreover, according to the excavation stirring head of the second invention of the present application, the ground improvement method of the first invention can be effectively carried out by using this head connected to the lower end of the stirring rod.

  As the “solidifying liquid” in the first and second inventions, a mixture of a solidifying agent such as cement and water, and various other solidifying liquids are used.

  As the “solidification liquid downward discharge port” in the second invention of the present application, the lower end surface of the hollow head rod is provided with a discharge port that opens downward, and the lower end of the solidification liquid supply pipe disposed on the outer peripheral surface of the head rod is A discharge port that extends downward to the lower end of the head rod and other various types are used.

  Further, in the “driving means for advancing and retracting the stirring rod” in the second invention of the present application, the stirring rod is slidably inserted into a cylinder provided in the head rod, and fluid pressure such as hydraulic pressure and hydraulic pressure is applied to the cylinder. Single-acting type to supply, double-acting type to supply / exhaust fluid pressure to the cylinder, advancing by spring and retreating by earth pressure, advancing by own weight and retreating by earth pressure, stirring blade Those that are advanced and retracted by thrust during forward and reverse rotation, those that combine any of the above, and other various types are used.

Furthermore, the “digging agitation head” of the second invention of the present application is, in use, a stirring rod in which various agitating blades such as a propeller shape and a rod shape are projected on the rod outer circumferential surface, and the rod outer circumferential surface has a smaller diameter than the excavating blade of the excavation agitation head. It is used by being connected to the lower end of a stirring rod having a continuous spiral blade projecting and other various stirring rods.
Embodiments of the present invention will be described in detail below with reference to the drawings.

  For convenience, an embodiment of the second invention of the present application will be described. FIG. 1 shows a ground improvement machine equipped with an excavation stirring head (A) according to the second invention of the present application, and a guide rail (3) of a mast (2) supported in an upright state at a front end portion of a base machine (1). 3) slidably support a rotary drive unit (4) having a motor, a speed reducer, etc., and hang up and down by a wire rope (5), and a helical blade (6 ′) is attached to its output shaft. A screw rod (6) having an excavation stirring head (A) connected to the lower end of the screw rod (6) is connected.

  The structure of the excavation stirring head (A) is as follows. 2, 3 and 4, two propeller-shaped excavating blades (8) and (8) each having an excavating blade (9) at the lower side on the outer peripheral surface of the lower end of the head rod (7) are rotated forward ( 2 and 3 are rotated in the direction of digging in the clockwise direction, and project radially at opposite positions in the diametrical direction, and on the outer peripheral surface of the head rod (7), the spiral blades of the screw rod (6) ( A spiral blade (7 ') having the same diameter as 6') is provided.

  In this example, the excavation diameter of the excavation blades (8) and (8) is larger than the diameters of the spiral blades (6 ′) and (7 ′) of the screw rod (6) and the head rod (7). As an example, about twice.

  A drilling blade driving cylinder (10), which will be described later, is drilled in the axial center position of the lower half of the head rod (7) of the excavation head as described above, and from the cylinder (10) from the lower end of the cylinder (10). Piston rod (stirring rod) (13) comprising a hexagonal column extending from a piston (12) inserted into the cylinder (10) through a small-diameter hexagonal hole (11) to the lower end surface of the head rod (7) Is inserted into the hexagonal hole (11) in a non-rotatable manner, protrudes from the lower end surface of the head rod (7), and the excavating blades (8), (8) are formed on the outer peripheral surface of the circular boss (14) fixed to the lower end of the protrusion. The two propeller-shaped second agitating blades (15) and (15) having the same diameter as that of the excavating blades (8) and (8) are opposed to each other as shown in FIG. Respectively, toward the tangential direction of the circular boss (14) It is projected.

  As shown in FIG. 4, the lower end surface of the head rod (7) is provided with a recessed storage chamber (16) in which the circular boss (14) is stored when the piston (12) is raised to the maximum. Notches (17) and (17) into which the stirring blades (15) and (15) enter are formed in the peripheral wall of the chamber (16). In this case, the agitating blades (15), (15) and the excavating blades (8), (8) indicate that the agitating blades (15), (15) are shown in phantom lines in FIG. As shown, the rear surfaces of the excavation blades (8) and (8) in the excavation rotation direction are in a positional relationship where they are housed in the alligators.

  A solidified liquid supply pipe (18) is piped along the longitudinal direction of the rod on the outer surface of the head rod (7), and a discharge port (19) connected to the lower end of the pipe (18) is connected to the excavating blade ( 8), slightly higher than the cutting edge of the excavating blades (9) of (8), and positioned downward from the upper side of the excavating blades (8), (8).

  As an internal line for supplying water pressure to the advance / retreat driving cylinder (10) of the second stirring blade and supplying the solidified liquid to the solidified liquid supply pipe (18), the upper half axial center of the head rod (7), A solidified liquid supply path (20) is formed concentrically with a hydraulic pressure supply path (21) on the outer side, and the lower end of the supply path (20) is connected to the solidified liquid supply pipe (18) via a connection path (22). And the lower end of the supply path (21) is connected to the upper end of the cylinder (10) via the connection path (23). The upper ends of the supply passages (20) and (21) are respectively connected to a solidified liquid pressure feeding device and a water pressure feeding device installed outside through a similar supply passage provided in the screw rod (6).

  An embodiment of the first invention of the present application using the above ground improvement machine will be described. With the second stirring blades (15) and (15) retracted, the rotation drive unit (4) is started to rotate the screw rod (6) forward, and the excavation blades (8) and (8) The ground is excavated by rotation, and a part of excavated soil is drilled while being conveyed upward by the spiral blades (7 ′) and (6 ′).

  After drilling at a predetermined depth as shown in FIG. 5 (a), as shown in FIG. 5 (b), while gradually rotating the screw rod (6), the drawing is started gradually, and the discharge port (19) Then, the solidified liquid is discharged downward and injected into the withdrawal trace of the head (A). At the same time, water pressure is sent into the cylinder (10) to lower the piston (12), and thereby the rotating stirring blades (15), (15) are advanced below the excavation blades (8), (8) to Stir and mix the injected solidified liquid with the excavated sediment. Almost all of the solidified liquid is used for mixing with the excavated earth and sand without being discharged upward. The excavated soil in the borehole is supplied under the excavated blades (8) and (8) by the reverse rotation of the excavated blades (8) and (8) and the spiral blades (7 ') and (6'), and solidified by injection. It is used for stirring and mixing with the liquid. (C) in the figure shows the injected solidified liquid.

  The soil (S) mixed with the solidified liquid as described above is accumulated in the drilling holes below the stirring blades (15) and (15) as shown in FIGS. After pulling out (6) from the drilling hole, the solidified liquid mixed earth and sand are filled, and this solidifies to form a high quality solidified earth and sand column.

  After pulling out, if the screw rod (6) is lowered and the agitating blades (15), (15) that have advanced are grounded, the piston (12) rises in the cylinder (10) and the cylinder (10 ) Is discharged, whereby the stirring blades (15) and (15) return to their original storage state.

It is a side view of the ground improvement machine provided with the excavation stirring head of this invention. It is an enlarged front view of the excavation stirring head which advanced the 2nd stirring blade. It is an enlarged bottom view same as the above. (A) It is the IV-IV sectional view taken on the line of FIG. (B) Partly omitted illustration of FIG. (A) with the stirring blades retracted. (A), (b), (c), (d) It is each sectional drawing which shows each ground which shows a ground improvement process.

Explanation of symbols

6 Screw rod 7 Head rod 8 Drilling blade 10 Cylinder 12 Piston 13 Piston rod 15 Second stirring blade 19 Discharge port A Drilling stirring head

Claims (2)

Using a drilling stirring rod having a drilling blade, a solidified liquid discharge port, and a second stirring blade capable of moving forward and backward at the lower end of the rod,
Drilling a predetermined depth in the ground by rotating the excavation stirring rod,
Next, while rotating and extracting the excavation stirring rod, the solidified liquid is injected into the extraction trace of the excavation stirring rod, and at the extraction trace, the injected solidified liquid and the excavation sediment are agitated and mixed by the second stirring blade. To go,
Ground improvement method. In the drilling head having a drilling blade and a solid solution downward discharge port located below the drilling blade at the lower end of the head rod,
At the head rod lower end axial center position of the excavation head, an agitation rod having a second agitation blade at the lower end is inserted and supported so as to be movable forward and backward in the axial extension direction from the lower end surface of the head rod and non-rotatable.
Provided with drive means for advancing and retracting the stirring rod;
Drilling stirring head.

Images