JP2008127864A - Fiber-reinforced cement-based soil improvement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fiber-reinforced cement-based soil improvement method which enables the uniform agitation of fibers and cement milk, and which enables ground to be reinforced only in a required location. <P>SOLUTION: The drilling of a vertical hole 48 is started by an auger section 25 of a construction machine 10; cement milk is ejected from an ejection port 30 of a rod 20; and the cement milk and sediment are agitated. When the auger section 25 reaches a boundary surface between a lower layer 44 and a hard layer 46, the pulling-out of the auger section 25 is started. In the location requiring the reinforcement of the ground, fiber-mixed sand 60 is fed from a hollow pipe 24; and the cement milk, the sediment, and the fiber-mixed sand 60 are agitated and mixed together. This enables the ground to be reinforced only in the required location. Additionally, the sand flows down by self-weight and air pressure, and the inside of the hollow pipe 24 is not clogged with the fibers. Consequently, the fibers, the sediment, and the cement milk can be uniformly agitated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fiber-reinforced cement-based ground improvement method for improving ground using fibers.

  Conventionally, there is a fiber reinforced ground improvement method in which a fiber is mixed in advance with a cement-based solidifying material solution to form a cement tough body with high toughness and the ground is improved (see, for example, Patent Document 1).

  In the fiber reinforced ground improvement method of Patent Document 1, fibers are added and dispersed in cement milk having a high viscosity at the lower limit of the water cement ratio that exhibits the required compressive strength.

However, the cement milk having a high viscosity cannot secure the fluidity of the solidifying agent liquid, and the pipe is clogged with fibers, or it is difficult for the solidifying agent liquid and the fibers to be separated and stirred uniformly.
JP 2003-232032 A

  An object of the present invention is to obtain a fiber-reinforced cement-based ground improvement method that can uniformly stir fibers and cement milk and can reinforce the ground only at necessary locations.

  The fiber-reinforced cement-based ground improvement method according to claim 1 of the present invention is a fiber-reinforced cement-based ground improvement method for improving the ground by stirring and mixing fibers, cement milk, and the ground, resulting in an improved depth of the ground improvement range. The first step of discharging cement milk from the pipe of the auger while drilling the ground with the auger until the cement milk and the ground are agitated and mixed, and the fiber from the hollow tube reaching the improved depth reinforced with the fiber And a second step of stirring and mixing the fibers, cement milk, and ground with the auger while pulling out the auger.

  According to the above-described configuration, the fibers of the auger are not clogged with the fibers by discharging the fibers from the separately provided hollow tube instead of the auger piping. And the cement milk and fiber are stirred uniformly by stirring the fiber thrown into cement milk with an auger.

  Moreover, the ground improvement body reinforced with the fiber only in the required location can be obtained by discharging | emitting a fiber from a hollow tube at the depth which requires fiber reinforcement.

  The fiber-reinforced cement-based ground improvement method according to claim 2 of the present invention is characterized in that, in the second step, fibers and sand are mixed and introduced into the hollow tube.

  According to the said structure, a fiber becomes easy to pass a hollow tube with the weight of sand.

  The fiber-reinforced cement-based ground improvement method according to claim 3 of the present invention is characterized in that, in the second step, fibers and sand are mixed and introduced into the hollow tube, and air pressure is applied to the hollow tube. Yes.

  According to the said structure, a fiber becomes easy to pass a hollow tube with the weight and air pressure of sand.

  Since this invention was set as the said structure, a fiber and cement milk can be stirred uniformly and the ground can be reinforced only in a required location.

  An embodiment of the fiber-reinforced cement-based ground improvement method of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the construction machine 10 is disposed on the ground 21.

  In the construction machine 10, a column 14 is erected in front of a crane 12 as a construction machine body. The column 14 is provided with a motor 16 suspended from the upper end of the column 14 via a wire 18 and moved up and down by a driving means (not shown).

  The motor 16 is formed with a connecting portion 18 and suspends two hollow cylindrical rods 20 connected to the connecting portion 18. The rod 20 can be turned by driving the motor 16.

  A hollow cylindrical hollow tube 24 is arranged between the two rods 20 in the vertical direction, and the two rods 20 and the hollow tube 24 are positioned by the guide member 22.

  The guide member 22 holds the rod 20 and the hollow tube 24 so that the pivot center position of the rod 20 does not shift.

  On the lower end side of the rod 22, an auger portion 25 for excavating the ground 21 to form a vertical hole and discharging cement milk or the like is provided.

  On the other hand, a plant 23 for generating cement milk is constructed on the ground 21 in the vicinity of the construction machine 10.

  The plant 23 includes a water tank 36, a cement silo 38, a mixing unit 40 that mixes water sent from the water tank 36 and cement sent from the cement silo 38 to generate cement milk, and cement milk in the mixing unit 40. And a pump 42 for delivering the gas to the pipe 44.

  One end of the pipe 44 is connected to the pump 42, and the other end is connected to the rod 20 described above. Thereby, the cement milk produced | generated in the plant 23 is sent in the inside of the rod 20. As shown in FIG.

  As shown in FIG. 2 a, in the auger portion 25, the lower ends of the two rods 20 are formed with discharge ports 30 through which cement milk or the like flowing down the rods 20 is discharged.

  The two rods 20 are fixed so as to be separated from each other by a predetermined distance by fixing members 26 and 28 (see FIGS. 2b and 2c) which are arranged at two places above and below and fastened with bolts and nuts.

  Further, a plurality of stirring blades 32 having inclined surfaces and a plurality of augers 34 are formed outward from the side wall of the rod 20.

  The stirring blade 32 and the auger 34 are provided with an excavation bit 36 having a blade portion for excavating the ground 21 (see FIG. 1) when the rod 20 rotates.

  On the other hand, the upper end portion of the hollow tube 24 is connected to a plant (not shown), and a mixture of sand and fibers is supplied to the hollow tube 24. In addition, a discharge port 27 is formed at the lower end of the hollow tube 24 from which the mixture of sand and fibers flowing down the hollow tube 24 is discharged.

  Here, as shown in FIG. 4 a, the fibers in the hollow tube 24 exist as fiber-mixed sand 60 that is a mixture of sand and fibers.

  Also, as shown in FIG. 4 b, one end of a hollow pipe 62 is connected to the upper end of the hollow tube 24 so that it can communicate, and the other end is connected to a compressor 64. Thus, when the compressor 64 is driven, air is sent into the pipe 62.

  Here, when air is fed into the pipe 62, the air pressure P is applied to the sand 60 mixed with fibers, and the fibers easily pass through the hollow tube 62 due to the weight of the sand and the air pressure P.

  Next, the operation of the embodiment of the present invention will be described.

  FIG. 3 shows a construction procedure when the ground 21 is improved.

  For the description of the construction procedure, the ground 21 is improved by using mainly cement without using fibers, an upper layer 40 on which a foundation such as a building is constructed, a soft layer 42 in which ground improvement using fibers is required, and the like. The lower layer 44 and the hard layer 70 that do not require ground improvement are displayed separately.

  In the present embodiment, the ground improvement layer 43 including the upper layer 40 and the soft layer 42 is subjected to ground improvement using fibers.

  As shown in FIG. 3 a, first, the construction machine 10 is placed on the ground 21.

  Subsequently, as shown in FIG. 3b, the motor 16 of the construction machine 10 is driven to rotate the rod 20, and the motor 16 and the auger section 25 are lowered to start excavation of the vertical hole 48. Further, the pump 42 (see FIG. 1) is driven, cement milk is discharged from the discharge port 30 (see FIG. 2) of the rod 20, and the cement milk and the earth and sand are agitated.

  Subsequently, as shown in FIG. 3 c, when the discharge port 30 of the auger portion 25 reaches the interface between the lower layer 44 and the hard layer 46, the motor 16 starts to rise and the extraction of the auger portion 25 is started. The rod 20 continues to rotate.

  Subsequently, as shown in FIG. 3d and FIG. 4, when the discharge port 27 (see FIG. 2) of the hollow tube 24 reaches the interface between the soft layer 42 and the lower layer 44, fibers are mixed into the hollow tube 24 from a plant (not shown). Sand 60 is supplied, and air pressure is further applied to the sand 60 mixed with fibers by the compressor 64. As a result, the fiber-mixed sand 60 is discharged from the discharge port 27 of the hollow tube 24.

  Subsequently, cement milk, earth and sand, and fiber-mixed sand 60 are stirred and mixed.

  Here, the sand flows down by its own weight and air pressure, and all the fibers inside the hollow tube 24 are pushed away, so that the fibers do not stay inside the hollow tube 24 and become clogged. Further, since the fibers are supplied as needed without staying, the fibers, earth and sand, and cement milk are evenly stirred.

  Subsequently, as shown in FIG. 3e, at the timing when the auger 25 is completely pulled up to the ground surface of the ground 21, the rod 20 stops turning, and the discharge of cement milk and the discharge of the fiber-mixed sand 60 are stopped. The Thereafter, the construction machine 10 is moved to finish the construction.

  The ground improvement of the ground improvement layer 43 is performed by the above construction procedure.

As described above, according to the embodiment of the present invention, the rod 20 is not clogged with the fiber by discharging the fiber from the hollow tube 24 provided separately instead of the rod 20 of the auger portion 25. Then, the agglomerate 25 stirs the fiber put into the cement milk, so that the cement milk and the fiber can be evenly stirred. Further, at the depth where the fiber reinforcement is required (the soft layer 42 and the upper layer 40), By discharging the fibers from the hollow tube 24, it is possible to obtain a ground improvement body reinforced with the fibers only at necessary portions.

  Furthermore, the fiber easily passes through the hollow tube 24 due to the weight and air pressure of the sand, and the hollow tube 24 is not clogged.

  In addition, this invention is not limited to said embodiment.

  The number of axes of the rod 20 may be one, or may be three or more.

The ground improvement using the fibers may be performed only in the soft layer 42 without being performed in the upper layer 40. Instead of the sand of the fiber-mixed sand 60, gravel, demolition glass, and recycled crushed stone may be used.

1 is an overall view of a construction machine according to an embodiment of the present invention. It is a block diagram of the auger part which concerns on embodiment of this invention. It is process drawing which shows the construction procedure of the fiber reinforced cement type ground improvement construction method which concerns on embodiment of this invention. It is a schematic diagram which shows the injection | throwing-in state of the fiber mixed sand to the hollow tube which concerns on embodiment of this invention.

Explanation of symbols

10 Construction machine 20 Rod (Piping)
21 Ground (Ground)
24 Hollow tube (hollow tube)
25 auger club
43 Ground improvement layer (Ground improvement range)
60 Fiber-mixed sand (fiber)
P Air pressure (pneumatic)

Claims (3)

In fiber reinforced cement-based ground improvement method to improve the ground by stirring and mixing fiber, cement milk and ground,
A first step of discharging cement milk from a pipe of the auger while drilling the ground with an auger up to an improved depth of the ground improvement range, and stirring and mixing the cement milk and the ground;
A second step of discharging the fiber from the hollow tube reaching the improved depth reinforced with the fiber, and stirring and mixing the fiber, cement milk, and ground with the auger while pulling out the auger;
A fiber-reinforced cement-based ground improvement method characterized by comprising:   2. The fiber-reinforced cement-based ground improvement method according to claim 1, wherein in the second step, fibers and sand are mixed and introduced into the hollow tube. The fiber-reinforced cement-based ground improvement method according to claim 1, wherein, in the second step, fibers and sand are mixed and introduced into the hollow tube, and air pressure is applied to the hollow tube.

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