JP2009275378A - Fiber-reinforced cement-based soil improvement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced cement-based soil improvement method which prevents piping for conveying fibers into ground from being clogged with the fibers. <P>SOLUTION: In a step of performing an agitation operation during the descent of an auger, cement milk and soil of original ground 10 are agitated for mixing by ejecting the cement milk from hollow pipes 24A and 24B, while the original ground 10 is drilled by the auger 30 until the auger 30 reaches an improvement depth in a soil improvement range while being lowered. In a step of performing an agitation operation during the ascent of the auger, the fibers S, the cement milk and the soil of the original ground 10 are agitated for mixing by means of the auger 30 by jetting the fibers S from a supply pipe 26 to a fiber reinforcement range to be reinforced by the fibers S, by air pressure, while the auger 30 is lifted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

The deep mixing agitation method adopted as one of the construction methods of the ground improvement body is to form the ground improvement body by kneading and solidifying the soil of the original ground and the cement hardening material.
In general, the deep-mixing mixing method is divided into a slurry-based deep mixing mixing method (DCM) and a powder jet mixing method (DJM) depending on how cement-based hardener is added. Yes.

In the slurry-based deep mixing and stirring method, the ground improvement body is formed by kneading and solidifying the soil of the original ground and the cement milk while jetting cement milk from the tip of the stirring rod.
In addition, the powder injection agitation method is a method in which the soil of the original ground and the powdered cementitious solidifying material are kneaded and solidified while injecting the powdery cementitious solidifying material from the tip of the stirring rod. Form an improvement.

The ground improvement body formed by these deep mixing and stirring methods tends to cause brittle fracture after reaching the maximum yield strength. Therefore, normally, safety is ensured by using a design value that is considerably lower than the average strength.
On the other hand, a method of increasing the toughness of the ground improvement body by mixing fibers into cement milk has been proposed.

In general, the amount of cement in the ground improvement body is determined according to the soil quality of the soil to be kneaded with the cement-based hardener so as to obtain a predetermined strength. For example, the cement amount for 1 m ³ of sand is about 80 to 150 kg, the cement amount for 1 m ³ of clay is about 100 to 300 kg, and the cement amount for silt 1 m ³ is about 100 to 200 kg.

Here, in the slurry-based deep mixing and agitation method, cement milk having a water cement ratio of 100% is generally used. Therefore, when the cement density is 3 g / cm ³ , about 127 to 150 liters per 1 m ^{3 of} sand, 1 m of clay soil ³ with respect to the order of 133 to 200 liters, it is necessary to mix the cement milk of about 133 to 167 liters relative to silt 1 m ^3.

When fibers are mixed in these amounts of cement milk so as to be 0.4 vol% with respect to the ground improvement body, the ratio of the fibers to cement milk is about 2.4 to 3.5 vol%. When mixing a fiber so that it may become 1.0 vol% with respect to an improved body, the ratio of the fiber with respect to cement milk will be about 6.0-8.8 vol%.
In this way, cement milk in a state where the viscosity is increased by mixing a large amount of reinforcing fibers has low fluidity, and therefore, the fibers are clogged in the pipe that conveys the cement milk mixed with fibers to the tip of the stirring rod. It is feared that it will end up.

As shown in FIG. 19, in the construction method of the fiber-reinforced soil cement solidified body of Patent Document 1, first, water, cement, and a water reducing agent are put into the mixer 250 and stirred while the mixer 250 and the agitator 252 are rotated. .
Further, while the mixer 250 and the agitator 252 are rotated, the thickener and the fiber are sequentially added and stirred to produce the fiber-mixed cement milk.

  Then, the fiber-mixed cement milk pumped by the pump 254 and the water pumped by the pump 258 from the water tank 256 are discharged into the ground from another system by the construction machine 260 to create an underground structure.

However, since the fiber-mixed cement milk has a high viscosity and low fluidity, there is a concern that the fiber may be clogged in a pipe that conveys the fiber-mixed cement milk to the construction machine 260.
JP 2003-232032 A

  This invention considers the fact which concerns, and makes it a subject to provide the fiber reinforcement cement-type ground improvement construction method which prevents this fiber being clogged in piping which conveys a fiber in the ground.

  The invention according to claim 1 is a fiber-reinforced cement-based ground improvement method for improving the ground by stirring and mixing cement milk, soil of the original ground, and fibers, while the auger is lowered in the ground improvement range while lowering the auger. The original ground is drilled with the auger until reaching an improved depth, and the cement milk is discharged from a hollow tube arranged in the auger to the ground improved range to remove the cement milk and the soil of the original ground. An auger lowering stirring step of stirring and mixing with the auger, and the fibers, the cement milk, and the raw ground by jetting the fibers pneumatically from a supply pipe to a fiber reinforced range reinforced with the fibers while raising the auger An auger rising stirring step of stirring and mixing the soil with the auger.

In the invention according to claim 1, the ground is improved by stirring and mixing the cement milk, the soil of the original ground, and the fiber.
In the auger lowering stirring step, the ground is drilled by the auger while the auger is lowered until the auger reaches the improvement depth in the ground improvement range. Then, the cement milk is discharged from the hollow tube arranged in the auger together with the hole drilled by the auger to the ground improvement range, and the cement milk and the soil of the original ground are stirred and mixed by the auger.

  In the auger ascending step, the fibers are injected by air pressure from the supply pipe to the fiber reinforced range where the auger is raised and reinforced with fibers. And this fiber, cement milk, and the soil of the original ground are stirred and mixed by an auger.

Therefore, since cement milk and fiber are not mixed and conveyed to the ground by separate pipes of the hollow pipe and the supply pipe, there is no possibility that these pipes are clogged with fibers. That is, it is possible to prevent the fibers from being clogged in the pipe that conveys the fibers into the ground.
In addition, cement milk and fiber have lower viscosities than cement milk mixed with fiber, so that cement milk and fiber can be transported by a relatively small power transport facility.

  By these, the ground improvement body using a fiber can be formed and construction of a rational ground foundation structure is attained. Since the ground improvement body using fiber has high toughness, the strength close to the average strength can be set as the design value, and the thickness can be made thinner than the conventional ground improvement body.

  The invention according to claim 2 is a fiber reinforced cement-based ground improvement method for improving ground by stirring and mixing cement milk, raw soil, and fibers, while the auger is lowered in the ground improvement range while lowering the auger. The original ground is drilled with the auger until the improved depth is reached, the cement milk is discharged from the hollow tube disposed in the auger to the ground improved range, and supplied to the fiber reinforced range reinforced with the fibers. An auger descending stirring step of jetting the fibers from a pipe with air pressure and stirring and mixing the fibers, the cement milk, and the soil of the original ground with the auger.

In the invention according to claim 2, the ground is improved by stirring and mixing the cement milk, the soil of the original ground, and the fiber.
In the auger lowering stirring step, the ground is drilled by the auger while the auger is lowered until the auger reaches the improvement depth in the ground improvement range. Then, the cement milk is discharged from the hollow pipe disposed in the auger together with the hole drilled by the auger to the ground improvement range. Further, together with the drilling of the original ground by the auger, the fiber is jetted pneumatically from the supply pipe to the fiber reinforced range reinforced with the fiber, and this fiber, cement milk and the soil of the original ground are mixed by stirring with the auger.
Therefore, an effect similar to that of the first aspect can be obtained.

  According to a third aspect of the present invention, the fiber, the cement milk, and the soil of the original ground are ejected by air pressure from the supply pipe to the fiber reinforcement range reinforced with the fiber while raising the auger. A stirring step when the auger is raised.

In the invention according to claim 3, in the stirring step when the auger is raised, the fiber is injected by air pressure from the supply pipe to the fiber reinforced range where the auger is moved up and down. And this fiber, cement milk, and the soil of the original ground are stirred and mixed by an auger.
Therefore, an effect similar to that of the first aspect can be obtained. Moreover, many fibers can be efficiently stirred and mixed.

  According to a fourth aspect of the present invention, there is provided a weighing means for weighing the fibers ejected from the supply pipe, the weighing means having a cutter roller provided with a cutting blade on an outer peripheral surface, and an elastic layer into which the cutting blade bites. Is formed on the outer peripheral surface, and includes an elastic roller for sandwiching continuous continuous fibers with the cutter roller.

In the invention described in claim 4, the fibers to be ejected from the supply pipe are weighed by the weighing means.
The weighing means includes a cutter roller and an elastic roller. A cutting blade is provided on the outer peripheral surface of the cutter roller, and an elastic layer is formed on the outer peripheral surface of the elastic roller. The cutter roller and the elastic roller are arranged so that the cutting blade provided on the outer peripheral surface of the cutter roller bites into the elastic layer formed on the outer peripheral surface of the elastic roller.

Therefore, the continuous long fibers can be cut by holding the continuous long fibers between the cutter roller and the elastic roller and rotating the cutter roller and the elastic roller.
Further, the amount of the cut fiber can be easily and continuously measured from the rotation speed and rotation time of the cutter roller and the elastic roller.

  In addition, by changing the rotation speed and rotation time of the cutter roller and the elastic roller, the amount of fiber to be cut can be easily adjusted, and the amount of fiber supplied per hour corresponding to the construction of the ground improvement body is secured. be able to.

Moreover, the length of the fiber to be cut can be easily changed by changing the diameter of the cutter roller or the pitch at which the cutting blade is provided.
In addition, since the fiber can be cut and measured with one device, space saving and cost reduction can be achieved.

  According to a fifth aspect of the present invention, there is provided a weighing means for weighing the fibers ejected from the supply pipe, and the weighing means is a batch type weighing device.

In the invention according to claim 5, the metering means is a batch type metering device, and the batch type metering device measures the fiber to be ejected from the supply pipe.
Therefore, the cut | disconnected fiber can be measured with a simple apparatus.

  According to a sixth aspect of the present invention, the metering means is provided in the supply pipe.

In the invention described in claim 6, the metering means is provided in the supply pipe.
Therefore, since the weighed fibers can be immediately injected into the ground from the supply pipe, it is possible to make the fibers more difficult to clog the supply pipe that conveys the fibers into the ground.

  The invention according to claim 7 pneumatically conveys the fibers from the metering means to the supply pipe.

  In the invention according to claim 7, since the fibers are conveyed by air from the measuring means to the supply pipe, large facilities such as a water tank and a water supply pump are not required for conveying the fibers.

  Since this invention set it as the said structure, it can prevent this fiber being clogged in piping which conveys a fiber in the ground.

A fiber-reinforced cement-based ground improvement method according to an embodiment of the present invention will be described with reference to the drawings.
First, the fiber-reinforced cement-based ground improvement method according to the first embodiment of the present invention will be described.

As shown in the side view of FIG. 1 and the front view of FIG. 2, the construction machine 12 is disposed on the ground 10.
In the construction machine 12, a column 16 is erected in front of a crane 14 as a construction machine body. The support column 16 is provided with a driving device 20 that is suspended from the upper end of the support column 16 via a wire 18 and moves up and down.

  The driving device 20 has a built-in motor (not shown), and by driving the motor, a hollow tube whose upper ends are connected to the two connecting portions 22A and 22B provided at the lower end of the driving device 20, respectively. The two rods 24A and 24B are rotated. The rods 24A and 24B have a hollow cylindrical shape.

  A hollow cylindrical supply pipe 26 is disposed between the two rods 24A and 24B in the vertical direction, and the two rods 24A and 24B and the supply pipe 26 are positioned by a guide member 28.

  The guide member 28 rotatably holds the rods 24A and 24B so that the turning center positions of the rods 24A and 24B are not shifted. The supply pipe 26 is fixed to the guide member 28.

  On the lower end side of the rods 24A and 24B, an auger portion 30 is provided for drilling the ground 10 to form vertical holes and discharging cement milk.

On the other hand, a plant 32 that generates cement milk is constructed in the vicinity of the construction machine 12 on the ground 10.
The plant 32 includes a water tank 34, a cement silo 36, a mixing unit 38 that mixes water sent from the water tank 34 and cement sent from the cement silo 36 to generate cement milk, and cement milk generated by the mixing unit 38. Is constituted by a pump 42 for delivering the gas to the pipe 40.

  One end of the pipe 40 is connected to the pump 42, and the other end is connected to rods 24 </ b> A and 24 </ b> B provided on the construction machine 12. Thereby, the cement milk produced | generated in the plant 32 is sent into the inside of rod 24A, 24B.

As shown in FIG. 3, in the auger portion 30, discharge ports 44A and 44B are formed at the lower ends of the rods 24A and 24B. Cement milk that has flowed down inside the rods 24A and 24B is discharged from the discharge ports 44A and 44B.
The rods 24A and 24B are rotatably held at a predetermined distance by fixing members 46 and 48 disposed at two locations above and below.

Further, a plurality of stirring blades 50 having a slope and a plurality of excavation blades 52 are provided from the side walls of the rods 24A and 24B toward the outside in the radial direction.
The excavation blade 52 is provided with an excavation bit 54 having a blade portion for excavating the ground 10 (see FIGS. 1 and 2) when the rods 24A and 24B rotate.

  On the other hand, since the upper end portion of the supply pipe 26 is connected to the fiber supply pipe 60 having one end connected to the fiber supply section 58 shown in FIG. 4, the short fibers S flow down through the supply pipe 26 and supply pipe Injected by air pressure from an injection port 56 formed at the lower end portion of 26.

As shown in FIG. 4, the fiber supply unit 58 includes a pneumatic feeding unit 62 and a fiber processing unit 64 arranged on the ground 10.
In the pneumatic feeding unit 62, compressed air is sent from the air compressor 68 to the air tank 70 via the air dehumidifier 66, and the compressed air is stored in the air tank 70. Then, compressed air is sent from the air tank 70 through the air supply pipe 72 to the rotary cutter 74 of the fiber processing section 64 as necessary.

  A reel 78 around which continuous long fibers F are wound is provided inside the airtight container 76 of the fiber processing unit 64, and the long fibers F are fed from the reel 78 to the rotary cutter 74 through the feed pipe 92.

As shown in FIG. 5, the rotary cutter 74 as the weighing unit includes a cutter roller 82 and an elastic roller 84.
Rubber layers 86 and 88 as elastic layers are formed on the outer peripheral surfaces of the cutter roller 82 and the elastic roller 84. The rubber layer 88 is thicker than the rubber layer 86.

Four cutting blades 90 are attached to the outer peripheral surface of the cutter roller 82 at equal intervals in the circumferential direction.
In addition, the cutter roller 82 and the elastic roller 84 are arranged so that the cutting blade 90 provided on the outer peripheral surface of the cutter roller 82 bites into the elastic rubber 88 formed on the outer peripheral surface of the elastic roller 84.

  The continuous long fiber F is sandwiched between the cutter roller 82 and the elastic roller 84 and sent to the fiber supply pipe 60 side (see FIG. 6A), and the cutter roller 82 and the elastic roller 84 are moved to the arrows. By rotating in the direction of 94, 96, the continuous blade F can be cut into the continuous blade F (see FIG. 6B) (see FIG. 6C).

The short fibers S as the cut fibers are sent to the fiber supply pipe 60 by the pressure of the compressed air sent from the air supply pipe 72 to the rotary cutter 74, and then are pneumatically conveyed through the fiber supply pipe 60 to the supply pipe 26. It is thrown.
Further, the short fibers S flow down the supply pipe 26 by the pressure of the compressed air sent from the air supply pipe 72 and are jetted by air pressure from the jet port 56 of the supply pipe 26.

  Therefore, the rotary cutter 74 can easily and continuously measure the amount of the cut short fibers S from the rotation speed and the rotation time of the cutter roller 82 and the elastic roller 84. That is, the short fibers S as the fibers to be ejected from the ejection port 56 of the supply pipe 26 can be measured by the rotary cutter 74 as the measuring means.

  Further, by changing the rotation speed and rotation time of the cutter roller 82 and the elastic roller 84, the amount of the short fiber S to be cut can be easily adjusted, and the fiber supply per hour corresponding to the construction of the ground improvement body. The amount can be secured.

  The diameter of the cutter roller 82 and the pitch of the cutting blades 90 attached to the outer peripheral surface of the cutter roller 82 may be changed. By changing the diameter of the cutter roller 82 and the pitch of the cutting blades 90 attached to the outer peripheral surface of the cutter roller 82, the length of the short fibers S to be cut can be easily changed.

  Next, the operation and effect of the fiber-reinforced cement ground improvement method according to the first embodiment of the present invention will be described.

FIG. 7 shows an example of a construction procedure when the ground 10 is improved by the auger section 30.
In order to explain the construction procedure, in FIG. 7, the ground 10 is composed of an upper layer 100 on which a foundation such as a building is constructed, a soft layer 102 that requires ground improvement using fibers, and mainly cement without using fibers. The lower layer 104 that improves the ground with milk and the hard layer 106 that does not require ground improvement are displayed separately.

In the first embodiment, the ground improvement layer 108 and the lower layer 104 composed of the upper layer 100 and the soft layer 102 are ground improved with cement milk, and the ground improvement layer 108 is ground improved with fibers. That is, the ground improvement layer 108 and the lower layer 104 are in the ground improvement range, and the ground improvement layer 108 is in the fiber reinforcement range.
As shown in FIG. 7A, first, the construction machine 12 is placed on the ground 10.

Next, as shown in FIG. 7 (b), the driving device 20 of the construction machine 12 is driven, the rods 24 </ b> A and 24 </ b> B are turned, and the driving device 20 and the auger unit 30 are lowered while the drilling bit of the drilling blade 52. The vertical hole 110 is drilled by 54. That is, the original ground (ground 10) is drilled by the auger part 30.
In addition, the pump 42 (see FIGS. 1 and 2) is operated together with the drilling of the vertical hole 110 by the auger section 30, and the ground improvement range from the discharge ports 44A and 44B (see FIG. 3) of the rods 24A and 24B. Cement milk is discharged.

  The drilling of the vertical hole 110 by the auger part 30 and the discharge of cement milk from the rods 24A, 24B to the ground improvement range are performed by the auger part 30 (discharge ports 44A, 44B) in the improvement depth of the ground improvement range (the lower layer 104 and the hard The process is performed until the vicinity of the boundary surface with the layer 106 is reached. At this time, the soil of the original ground (ground 10) and the cement milk are stirred and mixed by the stirring blade 50 of the auger section 30.

  That is, in the auger lowering stirring process so far, while the auger part 30 is lowered, the auger part 30 reaches the improvement depth of the ground improvement range (near the boundary surface between the lower layer 104 and the hard layer 106) (the ground) 10) is drilled by the auger 30 and cement milk is discharged from the discharge ports 44A and 44B of the rods 24A and 24B, and the cement milk and the soil of the original ground (ground 10) are stirred and mixed by the auger unit 30. Yes.

  Next, as shown in FIG. 7C, after the auger portion 30 (discharge ports 44A and 44B) reaches the improvement depth of the ground improvement range (near the boundary surface between the lower layer 104 and the hard layer 106), the driving device 20 To raise. As a result, the auger portion 30 is raised and extraction is started. The rods 24A and 24B are continuously turning.

  Next, as shown in FIG. 7D, the ejection port 56 (see FIG. 3) of the supply pipe 26 is a boundary between the soft layer 102 and the lower layer 104 while pulling up the driving device 20 and raising the auger portion 30. The short fiber S is supplied from the fiber supply part 58 to the supply pipe 26 until the auger part 30 is completely pulled up above the ground surface of the ground 10 after reaching the vicinity of the surface. Thereby, the short fiber S is jetted by air pressure from the jet port 56 of the supply pipe 26 to the fiber reinforcement range.

At this time, since the rods 24 </ b> A and 24 </ b> B are continuously swirling, the short fibers S, the cement milk, and the soil of the original ground (ground 10) are evenly stirred and mixed by the stirring blades 50 of the auger unit 30.
That is, in the auger rising stirring process so far, the short fibers S are pneumatically supplied from the injection port 56 of the supply pipe 26 to the fiber reinforcement range (ground improvement layer 108) reinforced with the short fibers S while raising the auger portion 30. The short fiber S, the cement milk, and the soil of the original ground (ground 10) are agitated and mixed by the auger unit 30 by spraying.

  Next, as shown in FIG. 7 (e), at the timing when the auger part 30 is completely pulled up above the ground surface of the ground 10, the rotation of the rods 24A and 24B is stopped, and the discharge of cement milk and the short fibers S are stopped. Is stopped. Thereafter, the construction machine 12 is moved to finish the construction.

  As described above, in the first embodiment, the short fibers S are injected not from the hollow tubes (rods 24A and 24B) disposed in the auger portion 30 but from the separately provided supply tube 26, The empty pipes (rods 24A and 24B) and the supply pipe 26 are not clogged with the short fibers S. That is, since the cement milk and the fiber are conveyed to the ground without being mixed, it is possible to prevent the fibers from being clogged in the pipe for conveying the fiber to the ground.

  Moreover, since the short fiber S can be injected from the injection port 56 of the supply pipe 26 at a timing different from the time when the cement milk is discharged, a ground improvement body reinforced with fibers only at a necessary depth can be constructed. .

  Further, after the soil of the original ground (ground 10) and the cement milk are agitated and mixed, the short fibers S are put into the soil and the cement milk and agitated and mixed by the agitating blade 50 of the auger 30. The cement milk, the soil of the original ground (ground 10), and the short fibers S can be evenly stirred and mixed.

  Also, cement milk and short fibers S have lower viscosities than cement milk mixed with short fibers S, so the cement milk and short fibers S can be transported separately with relatively small power transport equipment. can do. Further, since the short fibers S are conveyed from the measuring means (rotary cutter 74) to the supply pipe 26 by air conveyance, large facilities such as a water tank and a water supply pump are not required for conveying the short fibers S.

Further, since the fiber can be cut and measured with one device (rotary cutter 74), space saving and cost reduction can be achieved.
In addition, since the weighing means (rotary cutter 74) is on the ground, it is possible to cope with failure of the weighing means at an early stage.

  By these, the ground improvement body using a fiber can be formed and construction of a rational ground foundation structure is attained. For example, since the ground improvement body using fiber has high toughness, the strength close to the average strength can be set as the design value, and the thickness can be made thinner than the conventional ground improvement body.

Next, a fiber-reinforced cement-based ground improvement method according to the second embodiment of the present invention will be described.
In the second embodiment, the weighing means (rotary cutter 74) shown in the first embodiment is a batch-type weighing device. Therefore, in the following description, the same components as those in the first embodiment are denoted by the same reference numerals and are appropriately omitted.
In 2nd Embodiment, since the plant 32, the construction machine 12, and the auger part 30 (refer FIGS. 1-3) shown in 1st Embodiment are used, description is abbreviate | omitted about these.

  In 2nd Embodiment, the upper end part of the supply pipe | tube 26 provided between the two rods 24A and 24B of the construction machine 12 is the fiber supply pipe | tube 60 by which one end was connected to the fiber supply part 112 shown in FIG. Therefore, the short fibers S flow down in the supply pipe 26 and are injected by air pressure from the injection port 56 formed in the lower end portion of the supply pipe 26.

As shown in FIG. 8, the fiber supply unit 112 includes a pneumatic feeding unit 62 and a fiber storage unit 114. The configuration of the pneumatic feeding unit 62 is the same as that in FIG.
Compressed air is sent to the rotary feeder 116 of the fiber storage unit 114 from the air feeding pipe 72 connected to the pneumatic feeding unit 62 as necessary.

  In the fiber storage unit 114, the silo 118 in which the short fibers S are stored is disposed on the ground 10. This short fiber S may be supplied to the silo 118 after being cut at the factory, or the continuous long fiber F is cut at the site using the method shown in FIG. May be supplied to the silo 118. Further, the continuous long fibers F may be cut and supplied to the silo 118 on site using a method other than the method shown in FIG.

  As shown in FIG. 8, the short fibers S dropped from the silo 118 are weighed by a batch-type weighing device 120 as a weighing means, and then are secured from the rotary feeder 116 in a state where confidentiality is ensured. Sent out.

Here, the batch type weighing device 120 as the weighing means will be described.
As shown in FIG. 9, a hopper 122 is provided on the casing 124 of the weighing device 120.

In addition, a motor 130 that rotates a rotating shaft 128 provided vertically on the transmission 126 is provided in the casing 124 via the transmission 126.
A supply board 132 having a plurality of blades 134 (see FIG. 10) radially arranged on the outer peripheral edge is pivotally attached to the rotating shaft 128. Further, a conical stirring body 136 is pivotally attached to the rotary shaft 128 so as to be positioned above the supply board 132.

On the inner wall of the casing 124, a semi-annular scraping plate 138 that covers the rotation trajectory surface of the blade 134 at the upper end height of the blade 134 of the supply board 132 is fixed.
The rotation trajectory surface of the blade 134 that is not covered with the scraping plate 138 is the input surface of the input port 140 for the short fibers S.
As shown in FIG. 11, a gap 142 is formed on the lower surface of the scraping plate 138 by reducing the thickness of the scraping plate 138 except for the circumferential end.

As shown in FIGS. 9 and 12, a load cell 148 is provided in the casing 124 located in the vicinity of the lower right end of the hopper 122. A pressure receiving plate 146 is mounted on the upper surface of the balance table 144 of the load cell 148, and a short space accommodated in an accommodating space 152 partitioned by the side wall surface of the casing 124 and the side wall surface of the blades 134 on the pressure receiving plate 146. The fiber S is placed (see FIG. 10).
As shown in FIG. 9, a discharge port 150 is formed in the casing 124 located in the vicinity of the lower left end portion of the hopper 122.

First, as shown in FIGS. 9 and 10, the short fiber S introduced from the hopper 122 is sent to the input port 140 while being stirred by the rotating stirrer 136, and the measuring method is as follows. The fiber S is dropped and accommodated in each accommodation space 152.
Next, as shown in FIG. 11, the short fibers S accommodated in the accommodation space 152 are sequentially cut by the sliding plate 138 and transferred in the circumferential direction in a state where the volume of the accommodation space 152 is almost filled. .

Next, as shown in FIG. 10, the short fibers S accommodated in the accommodation spaces 152 pass over the pressure receiving plate 146 of the load cell 148 while being transported in the circumferential direction. Then, the weight of the short fiber S accommodated in the accommodation space 152 is measured continuously or intermittently by the load cell 148 at the moment when the short fiber S accommodated in each accommodation space 152 is placed on the pressure receiving plate 146. The Based on the weight value measured by the load cell 148 and the number of rotations per unit time of the rotating shaft 128, the supply amount of the short fibers S discharged from the discharge port 150 is obtained.
Next, when the accommodating space 152 that accommodates the weighed short fibers S reaches the discharge port 150, the short fibers S accommodated in the accommodating space 152 fall downward.

In this way, the short fibers S to be ejected from the supply pipe 26 can be measured by the simple measuring device 120.
Then, the short fibers S as the fibers are sent to the fiber supply pipe 60 by the pressure of the compressed air sent from the air supply pipe 72, and thereafter, the air is conveyed through the fiber supply pipe 60 and put into the supply pipe 26. .
Further, due to the pressure of the compressed air sent from the air supply pipe 72, the short fibers S flow down the supply pipe 26 and are injected pneumatically from the injection port 56 of the supply pipe 26.

  Next, the operation and effect of the fiber reinforced cement ground improvement method according to the second embodiment of the present invention will be described.

In the second embodiment, the ground 10 is improved by the auger portion 30 according to the construction procedure shown in FIG. 7 similar to the first embodiment.
In the second embodiment, in FIG. 7 (d), the driving device 20 is pulled up to raise the auger portion 30, while the injection port 56 (see FIG. 3) of the supply pipe 26 is formed between the soft layer 102 and the lower layer 104. The short fiber S is supplied from the fiber supply unit 112 to the supply pipe 26 until the auger unit 30 is completely pulled up above the ground surface of the ground 10 after reaching the vicinity of the boundary surface. Thereby, the short fiber S is jetted by air pressure from the jet port 56 of the supply pipe 26 to the fiber reinforcement range.

  Therefore, in the second embodiment, the hollow fibers (rods) are injected by injecting the short fibers S not from the hollow tubes (rods 24 </ b> A and 24 </ b> B) disposed in the auger unit 30 but from the separately provided supply tubes 26. 24A, 24B) and the supply pipe 26 are not clogged with the short fibers S. That is, since the cement milk and the fiber are conveyed to the ground without being mixed, it is possible to prevent the fibers from being clogged in the pipe for conveying the fiber to the ground.

  Moreover, since the short fiber S can be injected from the injection port 56 of the supply pipe 26 at a timing different from the time when the cement milk is discharged, a ground improvement body reinforced with fibers only at a necessary depth can be constructed. .

  Further, after the soil of the original ground (ground 10) and the cement milk are agitated and mixed, the short fibers S are put into the soil and the cement milk and agitated and mixed by the agitating blade 50 of the auger 30. The cement milk, the soil of the original ground (ground 10), and the short fibers S can be evenly stirred and mixed.

Also, cement milk and short fibers S have lower viscosities than cement milk mixed with short fibers S, so the cement milk and short fibers S can be transported separately with relatively small power transport equipment. can do. Further, since the short fibers S are conveyed from the measuring means (metering device 120) to the supply pipe 26 by air conveyance, large facilities such as a water tank and a water supply pump are not required for conveying the short fibers S.
In addition, since the weighing means (the weighing device 120) is on the ground, it is possible to quickly cope with a failure of the weighing means.

  By these, the ground improvement body using a fiber can be formed and construction of a rational ground foundation structure is attained. For example, since the ground improvement body using fiber has high toughness, the strength close to the average strength can be set as the design value, and the thickness can be made thinner than the conventional ground improvement body.

Next, a fiber-reinforced cement-based ground improvement method according to the third embodiment of the present invention will be described.
In the third embodiment, the metering means (rotary cutter 74) shown in the first embodiment is provided in the supply pipe. Therefore, in the following description, the same components as those in the first embodiment are denoted by the same reference numerals and are appropriately omitted.
In 3rd Embodiment, since the plant 32, the construction machine 12, and the auger part 30 (refer FIGS. 1-3) shown in 1st Embodiment are used, description is abbreviate | omitted about these.

In the third embodiment, as shown in FIGS. 13 and 14, the airtight container 76 shown in FIG. 4 is provided at the upper end of the supply pipe 26 provided between the two rods 24 </ b> A and 24 </ b> B of the construction machine 12. It has been. In addition, a rotary cutter 160 having the same mechanism as the rotary cutter 74 shown in FIG.
Then, the continuous long fibers F sent out from the airtight container 76 are supplied to the rotary cutter 160 through the supply pipe 26.

As shown in FIG. 13, fiber feeding devices 154 are provided along the length direction of the supply pipe 26 at several locations of the supply pipe 26.
In the fiber delivery device 154, as shown in FIG. 15 which is a BB side cross-sectional view of FIG. 13, the continuous long fibers F are sandwiched by a pair of rubber rollers 158A and 158B, and the rubber rollers 158A and 158A in the directions of arrows 156A and 156B 158B is rotated and the long fiber F is sent out downward.

As shown in FIGS. 13 and 14, the air supply pipe 72 having one end connected to the pneumatic supply section 62 extends to the rotary cutter 160 along the supply pipe 26, and the other end is connected to the rotary cutter 160. The configuration of the pneumatic feeding unit 62 in FIG. 14 is the same as that of the pneumatic feeding unit 62 in FIG.
Accordingly, as shown in FIG. 16, which is a cross-sectional side view taken along the line AA of FIG. 13, the cut short fibers S are injected by air pressure from the injection port 56 formed at the lower end portion of the supply pipe 26.

  Next, the operation and effect of the fiber-reinforced cement ground improvement method according to the third embodiment of the present invention will be described.

In the third embodiment, the ground 10 is improved by the auger portion 30 by the construction procedure shown in FIG. 7 similar to the first embodiment.
In the third embodiment, in FIG. 7D, the driving device 20 is pulled up to raise the auger portion 30, while the injection port 56 (see FIG. 3) of the supply pipe 26 is formed between the soft layer 102 and the lower layer 104. The short fiber S is conveyed from the rotary cutter 160 to the injection port 56 of the supply pipe 26 until the auger part 30 is completely pulled up to the ground surface of the ground 10 after reaching the vicinity of the boundary surface. Thereby, as shown in FIG. 16, the short fiber S is injected by air pressure from the injection port 56 of the hollow tube 26 to the fiber reinforcement range.

  Therefore, in the third embodiment, the hollow fibers (rods) are injected by injecting the short fibers S not from the hollow tubes (rods 24 </ b> A and 24 </ b> B) disposed in the auger unit 30 but from the separately provided supply tubes 26. 24A, 24B) and the supply pipe 26 are not clogged with the short fibers S. That is, since the cement milk and the fiber are conveyed to the ground without being mixed, it is possible to prevent the fibers from being clogged in the pipe for conveying the fiber to the ground.

  Moreover, since the short fiber S can be injected from the injection port 56 of the supply pipe 26 at a timing different from the time when the cement milk is discharged, a ground improvement body reinforced with fibers only at a necessary depth can be constructed. .

  Further, after the soil of the original ground (ground 10) and the cement milk are agitated and mixed, the short fibers S are put into the soil and the cement milk and agitated and mixed by the agitating blade 50 of the auger 30. The cement milk, the soil of the original ground (ground 10), and the short fibers S can be evenly stirred and mixed.

Also, cement milk and short fibers S have lower viscosities than cement milk mixed with short fibers S, so the cement milk and short fibers S can be transported separately with relatively small power transport equipment. can do.
Moreover, since the measuring means (rotary cutter 160) is provided in the vicinity of the lower end portion of the supply pipe 26, the measured short fibers S can be immediately injected from the injection port 56 of the supply pipe 26 into the ground. Therefore, it is possible to further prevent the fibers from being clogged in the pipe for conveying the fibers into the ground. Moreover, it is not necessary to secure the yard which cut | disconnects the continuous long fiber F, and the yard which stores this cut | disconnected short fiber S on the spot.

  By these, the ground improvement body using a fiber can be formed and construction of a rational ground foundation structure is attained. For example, since the ground improvement body using fiber has high toughness, the strength close to the average strength can be set as the design value, and the thickness can be made thinner than the conventional ground improvement body.

  In the first to third embodiments, as described with reference to FIG. 7, the example in which the short fibers S are injected into the fiber reinforcement range during the auger ascending step is shown. At this time, the short fibers S may be injected into the fiber reinforcement range.

  For example, the auger part 30 (discharge ports 44A, 44B) reaches the improvement depth of the ground improvement range (near the boundary surface between the lower layer 104 and the hard layer 106) while lowering the auger part 30 in the auger lowering stirring process. The original ground (ground 10) is drilled by the excavation blades 52 (excavation bit 54) of the auger section 30 until the ground.

  Then, cement milk is discharged from the discharge ports 44A and 44B of the rods 24A and 24B together with the drilling holes by the auger 30 to the ground improvement range (to the ground improvement layer 108 and the lower layer 104). Further, the short fiber S is sprayed by air pressure from the injection port 56 of the supply pipe 26 to the fiber reinforcement range (ground improvement layer 108) reinforced with the short fiber S together with the drilling of the original ground (ground 10) by the auger section 30. Then, the short fibers S, the cement milk, and the soil of the original ground (ground 10) are stirred and mixed by the stirring blades 50 of the auger section 30.

  According to this method, even when the ground is improved, it is possible to prevent the fibers from being clogged in the pipe that conveys the fibers into the ground as in the first to third embodiments. Thus, when the short fiber S is jetted into the fiber reinforcement range while drilling the ground 10, it is preferable to provide the discharge port 56 of the supply pipe 26 at the base of the excavation blade 52 shown in FIG.

  Further, in the auger rising stirring step after the auger lowering stirring step in which the short fibers S are jetted into the fiber reinforcement range as described above, the short fibers S may be sprayed again into the fiber reinforcing range.

  For example, in the auger rising stirring step after the auger descending stirring step, the auger portion 30 is raised from the injection port 56 of the supply pipe 26 to the fiber reinforcement range (ground improvement layer 108) reinforced with the short fibers S while being raised. The fiber S is jetted by air pressure. Then, the short fibers S, the cement milk, and the soil of the original ground (ground 10) are stirred and mixed by the stirring blades 50 of the auger section 30.

  In this way, if the short fibers S are injected into the fiber reinforcement range in both the auger lowering stirring step and the auger rising stirring step, many short fibers S can be efficiently stirred and mixed.

  Moreover, although the example using the construction machine 12 provided with the one supply pipe | tube 26 and the two rods 24A and 24B was shown in the 1st-3rd embodiment, one rod may be sufficient, 3 It may be more than a book. A plurality of supply pipes 26 may be provided. Then, the cement milk may be discharged from at least one of the provided rod and the supply pipe, and the short fiber S may be sprayed from at least one of the remaining rod and the supply pipe.

Alternatively, the rod or the supply pipe may be a double pipe, the cement milk may be discharged from one pipe of the double pipe, and the short fibers S may be jetted from the other pipe. When the rod is a double pipe, the supply pipe may not be provided.
When jetting the short fibers S from the rod, for example, it is preferable to provide an injection port for the short fibers S at the base of the excavation blade 52 shown in FIG.

Further, the ground improvement using the short fibers S may be performed only on the soft layer 102 without being performed on the upper layer 100.
The cement milk discharge port formed on the rod may be formed near the height of the injection port 56 of the supply pipe 26 in addition to the lower end of the rod. If it does in this way, cement milk and the soil of the ground 10 can be reliably stirred and mixed by the auger part 30 also in the upper layer of the ground improvement range which performs ground improvement with cement milk.

  In the first embodiment, the rotary cutter 74 is used as the weighing unit. In the third embodiment, the rotary cutter 160 is used as the weighing unit. However, the rotary cutter 160 is used as the weighing unit. Any metering means may be used as long as the continuous long fibers F can be cut and weighed.

  The rotary cutters 74 and 160 can easily adjust the amount of short fibers S to be cut by changing the rotation speed and rotation time of the cutter roller 82 and the elastic roller 84. Accordingly, the mixing amount of the short fibers S into the ground 10 can be easily adjusted. Further, the length of the short fibers S can be easily changed by changing the diameter of the cutter roller 82 and the pitch of the cutting blades 90 attached to the outer peripheral surface of the cutter roller 82. Adjust the short fiber S to increase the mixing amount of the original ground (ground 10) into the soil by shortening the length of the original ground (ground 10) by shortening the length of the original ground (ground 10) Can be easily performed.

  In the second embodiment, an example in which the weighing device 120 is used as the weighing means is shown. However, the weighing means used in the second embodiment may be any device that can measure the short fibers S in a batch type. . A metering device with a short metering time per batch is preferable so that it can follow the construction speed of ground improvement.

  Moreover, you may provide the discharge means which escapes the air injected with the short fiber S from the injection port 56 of the supply pipe | tube 26 to the ground. For example, as shown in FIG. 17, an outer pipe 162 is provided outside the supply pipe 26 so as to have a space between the supply pipe 26 and a double pipe is formed. You may make it lead to.

  Moreover, although the injection port 56 of the supply pipe 26 shown in the first to third embodiments faces downward, the short fibers S may be jetted in a lateral direction or an oblique direction. For example, as shown in FIG. 18, the nozzle 164 having the injection port 56 directed in the lateral direction may be rotated (arrow 166) together with the injection of the short fibers S.

  For the long fibers F shown in the first to third embodiments, polypropylene fibers, vinylon fibers, nylon fibers, and the like can be used. Polypropylene fiber is industrially produced, is versatile and inexpensive, and has the performance required as a reinforcing material, so it is suitable for long fiber F.

  The airtight container 76 and the rotary cutter 74 shown in the first embodiment, the rotary feeder 116 shown in the second embodiment, and the airtight container 76 and the rotary cutter 160 shown in the third embodiment are short fibers. In order to efficiently air-transfer S and to strongly inject it into the ground from the injection port 56 of the supply pipe 26, it is preferable to have high airtightness.

Further, in order to efficiently convey the short fibers S by air and to inject them strongly into the ground from the injection port 56 of the supply pipe 26, the pressure of the compressed air sent from the pneumatic feeding unit 62 may be 0.2 MPa or more. Preferably, it is 0.4 MPa or more.
Further, the fiber supply pipe 60 shown in the first and second embodiments can be more effectively prevented from clogging the short fiber S in the pipe if it is installed so that the radius of curvature is not reduced.

  As described above in the first to third embodiments of the present invention, the fiber-reinforced cement-based ground improvement method of the present invention controls the amount of fibers and cement used according to the properties of the original ground. Since it can mix in, the ground improvement body which has a predetermined dynamic performance with respect to various original grounds can be constructed | assembled.

  Moreover, since the ground improvement body using a fiber can be formed, construction of a rational ground foundation structure is attained. In other words, it is possible to reduce the ground improvement cross section for the purpose of self-supporting mountain retaining and prevention of liquefaction, adopt a direct foundation type for middle-rise or high-rise buildings, or increase the horizontal bearing capacity of pile-like improved bodies and wall piles. Rationalization can be achieved.

  The first to third embodiments of the present invention have been described above, but the present invention is not limited to such embodiments, and the first to third embodiments may be used in combination. Needless to say, the present invention can be implemented in various modes without departing from the gist of the present invention.

It is a side view which shows the construction machine which concerns on the 1st Embodiment of this invention. It is a front view which shows the construction machine which concerns on the 1st Embodiment of this invention. It is explanatory drawing of the auger part which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the fiber supply part which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the rotary cutter which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the effect | action of the rotary cutter which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the fiber reinforcement cement-type ground improvement construction method which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the fiber supply part which concerns on the 2nd Embodiment of this invention. It is a sectional side view which shows the measuring apparatus which concerns on the 2nd Embodiment of this invention. It is a top view which shows the measuring apparatus which concerns on the 2nd Embodiment of this invention. It is an enlarged view which shows the measuring device which concerns on the 2nd Embodiment of this invention. It is an enlarged view which shows the measuring device which concerns on the 2nd Embodiment of this invention. It is a front view which shows the construction machine which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows the pneumatic feeding part and airtight container which concern on the 3rd Embodiment of this invention. It is BB sectional drawing of FIG. It is AA sectional drawing of FIG. It is an enlarged view which shows the modification of the supply pipe | tube which concerns on embodiment of this invention. It is explanatory drawing which shows the modification of the injection nozzle of the supply pipe | tube which concerns on embodiment of this invention. It is explanatory drawing which shows the construction method of the conventional fiber reinforcement soil cement solidification body.

Explanation of symbols

10 Ground 24A, 24B Rod (hollow tube)
26 supply pipe 30 auger section (auger)
74, 160 Rotary cutter (Measuring means)
108 Ground improvement layer (fiber reinforcement range)
120 Weighing device (measuring means)
F Long fiber S Short fiber (fiber)

Claims (7)

In the fiber reinforced cement-based ground improvement method that improves the ground by stirring and mixing cement milk, soil of the original ground, and fiber,
While lowering the auger, the original ground is drilled with the auger until the auger reaches the improvement depth of the ground improvement range, and the cement milk is discharged from the hollow pipe disposed in the auger to the ground improvement range. An auger descending stirring step of stirring and mixing the cement milk and the soil of the original ground with the auger;
While raising the auger, when the auger is raised, the fiber, the cement milk, and the soil of the original ground are stirred and mixed with the auger by injecting the fiber from the supply pipe into the fiber reinforced range reinforced with the fiber. A stirring step;
A fiber-reinforced cement-based ground improvement method. In the fiber reinforced cement-based ground improvement method that improves the ground by stirring and mixing cement milk, soil of the original ground, and fiber,
While lowering the auger, the original ground is drilled with the auger until the auger reaches the improvement depth of the ground improvement range, and the cement milk is discharged from the hollow pipe disposed in the auger to the ground improvement range. Agitating step when the auger descends, wherein the fibers are jetted pneumatically from a supply pipe to a fiber reinforced range reinforced with the fibers, and the fibers, the cement milk, and the soil of the original ground are agitated and mixed with the auger,
A fiber-reinforced cement-based ground improvement method. While raising the auger, the auger ascending and mixing the fiber, the cement milk, and the soil of the original ground with the auger by injecting the fiber from the supply pipe into the fiber reinforced range reinforced with the fiber by air pressure Stirring process,
The fiber-reinforced cement-based ground improvement method according to claim 2, comprising: Measuring means for measuring the fibers to be ejected from the supply pipe;
The weighing means includes
A cutter roller provided with a cutting blade on the outer peripheral surface;
An elastic layer in which the cutting blade bites is formed on the outer peripheral surface, and an elastic roller for sandwiching continuous long fibers with the cutter roller;
The fiber reinforced cementitious ground improvement construction method according to any one of claims 1 to 3. Measuring means for measuring the fibers to be ejected from the supply pipe;
The fiber-reinforced cement-based ground improvement method according to any one of claims 1 to 3, wherein the weighing means is a batch-type weighing device.   The fiber-reinforced cement-based ground improvement method according to claim 4, wherein the measuring means is provided in the supply pipe.   The fiber-reinforced cement-based ground improvement method according to claim 4 or 5, wherein the fibers are pneumatically conveyed from the measuring means to the supply pipe.

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