JP6274347B1 - Deep layer processing equipment using internal pressure relief blades - Google Patents

Abstract

Disclosed is a deep mixing processing apparatus using multistage internal pressure relief blades that relieve earth pressure applied to a rotating shaft. In a deep mixing apparatus, a multi-stage internal pressure relief blade (22) that loosens a ground (10) around the rotation shaft (14) and relieves earth pressure applied to the rotation shaft (14) above an agitating blade (16) on the rotation shaft (14). Is provided so that the width direction thereof substantially coincides with the axial direction of the rotary shaft 14, and the internal pressure relief blade 22 satisfies L ≦ a + 2b, a ≧ β / α, and D / 4 ≦ b ≦ D / 2. Configure. D: Diameter of the rotating shaft 14, a: Width of the inner pressure relaxing blade 22, b: Length of the inner pressure relaxing blade 22, L: Installation interval of the inner pressure relaxing blade 22, β: Penetration speed per unit time of the rotating shaft 14, α: The number of rotations of the rotating shaft 14 per unit time. [Selection] Figure 1

Description

  The present invention is a deep mixing treatment apparatus for injecting a slurry-like cement-based improving material into soft ground such as sandy soil, silty clay, etc., and stirring and mixing with a large-diameter stirring blade in situ to form an improved ground The present invention relates to a deep mixing treatment apparatus using an internal pressure relief blade that loosens the ground around the rotation axis and relieves earth pressure applied to the rotation axis.

The deep mixing process method (slurry type mechanical stirring method) represented by the CDM (registered trademark) method is a ground improvement method mainly for soft ground to prevent consolidation settlement and deformation prevention. If the standard of the number of stirrings per 1 m of the stirring shaft is satisfied, an improved ground having the required design strength can be obtained.
In recent years, this method has often been used as a disaster prevention measure and earthquake countermeasure after major earthquakes such as Hanshin, Hokuetsu, and East Japan. In addition, ground, piles, and structures are coupled in energy-related facilities and port facilities. An increasing number of cases are being adopted as a relatively high-strength ground improvement method with an improved strength of about 3.0 to 5.0 MN / m ² for seismic reinforcement and sand ground.

  At present, there are methods that give priority to cost by increasing the diameter and number of axes, and methods that specialize in the combination of high-pressure injection, special injection, and mechanical stirring. These are mechanical equipment-prioritized construction methods, so the equipment configuration is different from the conventional slurry-type mechanical stirring method, and the versatility with the conventional method is low. Also, since it specializes in mechanical devices and machine configurations, it is often targeted for a specific ground.

  The diameter of the uniaxial or biaxial agitator blade of the deep mixing treatment method in land construction has been expanded from φ1,000 mm to φ1,300 mm, but by further increasing the diameter (for example, φ1,600 mm), In order to provide a more economically superior deep mixing method, it has been desired to establish a large-diameter deep layer processing method.

  The large-diameter deep-bed mixing method is a case where when the target ground has a deep construction depth such as a piled clay soil layer or hard sand layer, the weight of the processing machine is reduced by friction and the penetration capacity gradually decreases, making the construction impossible. There is. In general, to cope with hard ground, the penetration capacity is increased by enlarging the motor of the processing machine, the existing maximum processing capacity of 90 kW to 120 kW is used, and a drill bit is used at the tip of the cutting edge The drilling capacity is increased.

  In addition, in the case of soil that is difficult to stir and mix, such as the ground where the soil particles are fine and the viscosity is very strong, even if cement slurry is poured and stirred, the mixture becomes dumped around the stirring blades, causing a co-rotation phenomenon There is a case that does not mix well. In that case, the water-cement ratio (hereinafter referred to as W / C) may be extremely increased, but there is a problem that the cement slurry causes material separation, and the amount of cement added is greatly increased in order to obtain the target strength. Therefore, the construction is forced to be excessively large, and the cement slurry does not sufficiently enter the soil, causing problems in construction such as overflowing upward. In such construction, there has been a need for a construction method that reduces the reduction in construction efficiency and material loss, and prevents the occurrence of troubles such as breakage of the stirring blade, impenetrability, and inability to pull out as much as possible.

  In general, construction on hard ground causes a decrease in construction efficiency and material loss, and troubles such as breakage of the processing machine, breakage of the stirring blade, impenetrability, and inability to pull out have occurred. It is essential to establish a construction method for large-diameter, deep-layer mixing method that can sufficiently handle hard ground, and it is necessary to prevent the drive part for rotating the rotating shaft from becoming too resistant and causing construction failure. I must.

In Patent Documents 1 and 2, a method is known in which a small auxiliary blade is attached to a stirring shaft in addition to the stirring blade and is stirred.
In Patent Document 1, the ground is prepared by stirring and mixing the solidified material discharged from the discharge port at the tip of the stirring shaft and the soil by rotating and rotating the stirring shaft having a plurality of excavation heads and stirring blades at the tip. In the ground improvement method to be improved, rod-like or plate-like stirring auxiliary members are radially attached at predetermined intervals to the upper part of the stirring shaft on the outer periphery of the stirring shaft, and a circle for reducing displacement given to the surrounding ground. A ground improvement device is described in which a plate-like stirring auxiliary member is attached to the stirring shaft.
In Patent Document 2, the stirring shaft having a plurality of excavating blades and stirring blades at the tip is rotated and moved up and down, and the soil is stirred and mixed together with the solidified material and compressed air sprayed from the spray nozzle of the stirring blade. In the ground improvement method for improving the ground, a ground mixing treatment apparatus is described in which plate-like air recovery rib members are continuously provided on the outer periphery of the stirring shaft in pairs from the stirring blade to the upper end of the stirring shaft.

JP-A-8-184030 JP 2000-290993 A

  The ground improvement device described in Patent Document 1 is a numerical value related to the shape and dimensions of a rod-like or plate-like stirring auxiliary member and a disk-like stirring auxiliary member with respect to the diameter of the stirring shaft, and the mounting pitch on these stirring shafts. Is not described, it can only be estimated from the drawing. As estimated from the drawing of Patent Document 1, the protruding length of the bar-like or plate-like stirring auxiliary member to the side is about twice the diameter of the stirring shaft. Coupled with the fact that the bar-like or plate-like stirring auxiliary member having such a length is provided in multiple stages, the resistance applied to the driving device increases. In order to make the stirring blade larger in diameter than in the past, it is necessary to enlarge the drive device. In addition, since the mounting pitch interval of the stirring auxiliary member on the stirring shaft is as wide as 7 to 8 times the width of the stirring auxiliary member, it is not possible to sufficiently loosen the soil adhering around the stirring shaft when the stirring shaft penetrates, This also increases the resistance applied to the drive unit. Therefore, there has been a problem that it becomes increasingly difficult to make the stirring blade larger in diameter.

  The ground mixing treatment apparatus described in Patent Document 2 is a method of stirring and mixing soil with a stirring blade accompanied by a solidified material and compressed air. The protruding amount of the rib material is the outer circumference of the shaft when the stirring shaft is rotated. It is described that a gap is formed between the soil and the original position soil, and the air discharged from the injection nozzle through the gap is set to be easily released to the ground surface. The rib material in this construction method has an effect only for the purpose of air recovery, and is provided in pairs over the entire length of the stirring shaft, so that a very large load is applied to the rotary drive device. Therefore, there is a problem that it is necessary to use a larger driving device in order to increase the diameter of the stirring blade which is the object of the present invention.

The first problem to be solved by the present invention is to use an internal pressure relief blade that makes it possible to use a stirring blade having a larger diameter than in the past by using a drive device having a capacity that has been conventionally used. It was the establishment of the deep mixing processing equipment.
The second problem to be solved by the present invention is to provide a deep mixing treatment apparatus using an internal pressure relief blade that solves the first problem in a simple and economical manner.

As shown in FIG. 5, the present applicant prepares a conventional rotary shaft (without internal pressure relief blade) (1) and rotary shafts (2), (3) and (4) to which the internal pressure relief blade of the present invention is attached. The experiment was repeated with various parameters such as the diameter of the stirring blade, the presence or absence of compressed air injected during the stirring, the presence or absence of the flow additive, and the presence or absence of the internal pressure relief blade. Thus, it was found that the penetration resistance is greatly reduced even when a large-diameter stirring blade is used.
Specifically, when the penetration resistance of the rotating shaft with a stirring blade is measured as the current value of the motor of the drive unit, as shown in FIGS. 6 (a) and 6 (b), the conventional rotating shaft (internal pressure relaxation) (1) and the rotating shaft (2) (3) (4) to which the internal pressure relief blade of the present invention is attached are particularly different in resistance value (current value) at the time of penetration. I found

Specifically, in the conventional rotating shaft (without the internal pressure relaxation blade) shown in FIG. 5 (1), N = 20 as shown by the solid line in FIG. 6 (a) at the diameter φ = 1,000 mm of the stirring blade. In the case of sandy soil, the current value of the motor of the driving unit reached about 300A.
On the other hand, in the stirring blade diameter φ = 1,600 mm to which the internal pressure relaxation blade of the present invention shown in FIG. 5 (2) is attached, as shown by the dotted line in FIG. At that time, the current value of the motor of the driving unit was about 130A.
As shown by the one-dot chain line in FIG. 6 (a), the stirring blade diameter φ = 1,600 mm to which the internal pressure relaxation blade of the present invention shown in FIG. 30A.
When the stirring blade diameter φ = 1,600 mm to which the internal pressure relaxation blade of the present invention shown in FIG. 5 (4) is attached, with compressed air, with no fluid additive, and with pre-drilling, the two-dot chain line in FIG. As shown, it was about 120A.

The deep mixing treatment apparatus according to the present invention penetrates and withdraws the ground 10 while rotating the rotary shaft 14 having the excavating blade 15 and the stirring blade 16 at the tip portion, and injects cement slurry from the tip portion of the rotary shaft 14 to turn the ground. In the deep mixing treatment method and the apparatus in which the solidification improved body 25 is constructed by stirring 10,
A multistage internal pressure relief blade that loosens the ground 10 around the rotation shaft 14 and relaxes the earth pressure applied to the rotation shaft 14 at a position from the upper part of the stirring blade 16 to the lower end of the drive unit 17 in the rotation shaft 14. 22 is provided such that the width direction thereof substantially coincides with the axial direction of the rotating shaft, and the internal pressure relief blade 22 is configured to satisfy the following conditions.
L ≦ a + 2b
a ≧ β / α
D / 4 ≦ b ≦ D / 2
Where D: diameter of the rotating shaft 14 (cm)
a: Width (cm) of the internal pressure relief blade 22
b: Length (cm) of the internal pressure relief blade 22
L: Mounting interval (cm) of the internal pressure relief blades 22 on the rotary shaft 14
β: penetration speed per unit time of the rotating shaft 14 (cm / min)
α: Number of rotations of the rotating shaft 14 per unit time (times / minute)

At least one internal pressure relief blade 22 is provided in each stage.
It is desirable that the internal pressure relief blades 22 be arranged in a spiral shape with the center angle of each step shifted by a predetermined angle.

Pressure relieving blade 22, with a central angle providing two shifted 180 degrees to each stage, is provided by shifting the central angle of 90 degrees above and below the stage, also provided two staggered 180 degrees center angle to each stage The internal pressure relief blades 22 are arranged on a line orthogonal to the axial direction of the rotary shaft 14.

  The two internal pressure relief blades 22 provided with the center angle shifted by 180 degrees at each stage may be arranged on a line that intersects the axial direction of the rotating shaft 14 at an angle other than 90 degrees.

  The stirring blade 16 is based on a conventional plate shape, and has a trapezoidal shape, a semicircle, a semi-elliptical shape, etc., thereby reducing the resistance to the ground and reducing the stirring resistance. This is to prevent the drive unit 17 for rotating the rotating shaft 14 from being subjected to a large resistance and causing inability to perform the construction, and uses a shape having a low resistance and causing no problem in mixing efficiency.

  More preferably, the cement slurry is made of mixed air and discharged, and further injected with a fluid additive that enhances the fluidity of the cement slurry and fluidizes the soil immediately after mixing.

  The rotary shaft 14 may be a single-shaft type or a multi-axis type.

According to invention of Claim 1,
A deep layer in which a solidified improved body is constructed by rotating and rotating a rotary shaft having a drilling blade and a stirring blade at the tip while penetrating into and pulling out from the ground, discharging cement slurry from the tip of the rotary shaft and stirring the ground In the mixing processing device,
A multistage internal pressure relief blade that loosens the ground around the rotation shaft and relieves earth pressure applied to the rotation shaft above the stirring blade in the rotation shaft, the width direction of which is substantially the same as the axial direction of the rotation shaft. This internal pressure relief blade is
L ≦ a + 2b
a ≧ β / α
D / 4 ≦ b ≦ D / 2
Where D: diameter of the rotating shaft a: width of the inner pressure relaxing blade b: length of the inner pressure relaxing blade L: interval between the inner pressure relaxing blades on the rotating shaft β: penetration speed per unit time of the rotating shaft α: of the rotating shaft Since it is configured to satisfy the condition of the number of revolutions per unit time,
Due to the effect of loosening the ground around the rotating shaft by the internal pressure relief blade, the stirring resistance value when the rotating shaft penetrates is greatly reduced. For this reason, in the past, deep-mixing processing machines have increased penetration capacity by increasing the motor of the processing machine, and if a processing capacity normally used is predicted to be insufficient, a larger motor is used. In the invention, a large-diameter deep layer mixing method can be performed using a conventional motor. Incidentally, according to FIG. 6A, the resistance value (current value) could be suppressed to ½ or less even when the diameter was increased from 1,000 mm to 1,600 mm.

  According to the second aspect of the present invention, it is possible to achieve the effect of loosening the ground around the rotation axis by providing at least one internal pressure relief blade at each stage.

According to the inventions of claims 3 and 4, the internal pressure relief blades are arranged in a spiral form with the center angle of each stage shifted by a predetermined angle, or provided with two center angles shifted by 180 degrees on each stage, by or provided by shifting the central angle of 90 degrees above and below the stage, it is possible to apply a pressure of the rotation axis equally.

  According to the fifth and sixth aspects of the present invention, the two internal pressure relief blades provided with the center angle shifted by 180 degrees at each stage are arranged on a line orthogonal to the axial direction of the rotating shaft, or the axial direction of the rotating shaft By placing them on a line that intersects at an angle other than 90 degrees, it is possible to efficiently unravel the ground.

  According to the inventions of claims 7 and 8, the stirring blade adopts a trapezoidal, semicircular or semielliptical longitudinal section, thereby reducing the penetration resistance due to compressed air and using a flow additive. Improvement is possible even on hard sand ground (N> 30), which is difficult to penetrate with ground improvement machines.

  According to the ninth aspect of the present invention, when the compressed air is mixed and injected into the slurry, the surplus air from the tip of the stirring blade relieves the earth pressure by utilizing the gap generated by the rotation of the internal pressure relief blade. In addition, since the internal pressure relief blades are intermittently attached along the rotation axis, they are discharged to the ground. In addition, the cement slurry can be made into a liquid state by causing plastic fracture to the sand ground by air acceleration, and the cement slurry can be smoothly mixed.

  According to the invention of claim 10, by increasing the fluidity of the cement slurry and injecting a fluid additive that fluidizes the soil immediately after mixing, a significant stirring resistance value can be obtained regardless of the difference in the formation. Can be expected to decrease. Incidentally, according to FIG. 6A, even when the diameter is increased from 1,000 mm to 1,600 mm, the resistance value (current value) can be suppressed to a fraction or less.

  According to the invention described in claims 11 and 12, the effect of the internal pressure relief blade can be expected regardless of whether the rotating shaft is a single shaft type or a multi-axis type.

It is the whole front view which shows Example 1 of the deep layer mixing processing apparatus using the internal pressure relaxation blade by this invention. 1 shows details of the internal pressure relief blade 22 in FIG. 1, (a) is a front view of a part of the rotating shaft 14 to which the internal pressure relief blade 22 is attached, and (b) is another example of the internal pressure relief blade 22. A cross-sectional view, (c), is a front view of still another example of the internal pressure relief blade 22. The state of destruction of the soil of the internal pressure relief blade 22 according to the present invention is shown, (a) is an explanatory diagram in the case of clay, (b) is an explanatory diagram in the case of sand. The case of the biaxial type of the deep mixing processing apparatus by this invention is shown, (a) is a front view, (b) is a cross-sectional view. It is a figure which shows a verification test specification list. It shows the stirring resistance value (current value) during construction in the demonstration test, (a) is a diagram showing the stirring resistance value (current value) at the time of penetration, (b) is the stirring resistance value (current) at the time of pulling out Value). FIG. 6 is a comparative diagram of the penetration force (N · m) according to the shape of the stirring blade, wherein (a) is a characteristic diagram (1) according to the difference in the φ size of the stirring blade in which the conventional plate blade is inclined at 45 degrees and the present invention. (2), (3), (4), and (b) are diagrams illustrating an example in which the cross section of the stirring blade according to the present invention is trapezoidal, (c) These are explanatory drawings of the example which made the cross section of the stirring blade by this invention semicircular, (d) is explanatory drawing of the example which made the cross section of the stirring blade by this invention semi-elliptical.

The deep mixing treatment apparatus of the present invention penetrates and withdraws the ground 10 while rotating the rotary shaft 14 having the excavating blade 15 and the stirring blade 16 at the tip portion, and injects cement slurry from the tip portion of the rotary shaft 14 to ground. In the deep-mixing processing apparatus in which the solidified improvement body 25 is constructed by stirring 10
A multistage internal pressure relief blade that loosens the ground 10 around the rotation shaft 14 and relaxes the earth pressure applied to the rotation shaft 14 at a position from the upper part of the stirring blade 16 to the lower end of the drive unit 17 in the rotation shaft 14. 22 is provided such that the width direction thereof substantially coincides with the axial direction of the rotating shaft, and the internal pressure relief blade 22 is configured to satisfy the following conditions.
L ≦ a + 2b
a ≧ β / α
D / 4 ≦ b ≦ D / 2
Where D: diameter of the rotating shaft 14 (cm)
a: Width (cm) of the internal pressure relief blade 22
b: Length (cm) of the internal pressure relief blade 22
L: Mounting interval (cm) of the internal pressure relief blade 22 of the rotating shaft 14
β: penetration speed per unit time of the rotating shaft 14 (cm / min)
α: Number of rotations of the rotating shaft 14 per unit time (times / minute)

An example in which at least one internal pressure relief blade 22 is provided in at least one stage, an example in which the central angle of each stage is shifted by a predetermined angle and a spiral arrangement, two central axes are shifted by 180 degrees in each stage, and examples provided by shifting the central angle of 90 degrees stage, pressure relieving wings 22 provided two staggered 180 degrees center angle to each stage, an example of placing on a line perpendicular to the axial direction of the rotary shaft 14, each stage The two internal pressure relaxation blades 22 provided with the center angle shifted by 180 degrees at the same angle may be arranged on a line intersecting the axial direction of the rotating shaft 14 at an angle other than 90 degrees.

  The stirring blade 16 may be appropriately selected from a trapezoidal, semicircular or semielliptical vertical section.

Penetration is achieved by using a deep mixing treatment method in which compressed air is mixed and injected into the cement slurry, or a deep mixing treatment method in which the fluidity of the cement slurry is increased and fluid additives that fluidize the soil immediately after mixing are injected. The stirring resistance at the time can be reduced.
The rotating shaft 14 may be a single-axis type or a multi-axis type.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 10 denotes a soft ground, and shows an example in which a solidified improved body 25 is to be constructed on the ground 10.
A base machine 11 is installed on the ground 10, and a leader 12 is supported by a stay 13 and fixed vertically. The leader 12 is fixed to the upper support part 26, an intermediate steadying part 19, and a base steadying part 18. The rotating shaft 14 is held. A drilling blade 15 is provided at the lower end of the rotating shaft 14, and a plurality of stages of stirring blades 16 are attached on the drilling blade 15. In addition, a drive unit 17 is provided at the upper end of the rotary shaft 14 so as to penetrate the rotary shaft 14 into the ground 10 and pull it out. A slurry injection pipe 20 and an air injection pipe 21 for sending cement slurry and compressed air are coupled to the upper end of the rotary shaft 14. The cement slurry and compressed air sent from the slurry injection pipe 20 and the air injection pipe 21 enter the soil from the excavation blade tip discharge port 15 and / or the cement slurry discharge port 23 in the blade of the stirring blade 16 into the soil when the ground is stirred. Be injected. Further, when the stirring shaft is a double rod, it can be discharged from the cement slurry discharge port 23 and the air discharge port 24 separately.

An internal pressure relief blade 22 that is configured peculiar to the present invention is provided from the upper end to the lower end of the rotating shaft 14. The reason why this internal pressure relief blade 22 has been adopted is to increase the construction efficiency by making the stirring blade 16 have a large diameter (for example, φ1,600 mm) and to provide a more economical deep mixing treatment method. It is in that.
The applicant of this patent repeated the experiment by changing various parameters such as the diameter of the stirring blade, the presence or absence of compressed air injected during stirring, the presence or absence of a fluid additive, and the presence or absence of an internal pressure relief blade that loosens the adhering soil around the rotating shaft. As a result, it has been found that the penetration resistance can be greatly reduced by using a suitably shaped internal pressure relief blade even when a large-diameter stirring blade is used.

As shown in FIG. 2A, the internal pressure relief blade 22 basically has a shape of a width a and a length b, and is attached to the outer periphery of the rotating shaft 14 with an interval L between the steps. These dimensions a, b, and L are desired to have the following characteristics.
(1) The internal pressure relief blade 22 acts to relieve internal pressure generated between the rotary shaft 14 and the ground 10 when the rotary shaft 14 rotates.
(2) The rotational torque of the rotating shaft 14 is weakened, the generated peripheral surface adhesion force is reduced, and the pressure is diffused upward.
(3) When compressed air is mixed with cement slurry and used, excess compressed air must be removed upward without being retained in the ground 10.
(4) When a fluid additive is used in cement slurry, make the agitated soil easier to mix.
(5) Avoid that the ground 10 that has been agitated due to too many internal pressure relief blades 22 or too narrow intervals between the steps is discharged upward.
(6) During the creation, even if the stirring blade 16 at the tip of the rotating shaft 14 is stirred due to underground stress or slurry internal pressure depending on the depth, if the stirring blade 16 passes, the internal pressure around the rotating shaft 14 is reduced. Generation can be suppressed instantaneously.
(7) The internal pressure relief blade 22 is subjected to external force due to the rotation of the internal pressure relief blade 22 during the formation of the rotating shaft 14 during penetration and withdrawal, and shear stress is generated in the ground 10. Shear fracture occurs where the shear resistance is exceeded. The fracture surface is called a slip surface, and the maximum shear resistance that resists shear stress is generated, leading to fracture.
The failure pattern of the slip surface is different between clay and sand.
In the case of clay, the length b of the internal pressure relief blade 22 and the influence range x in which the ground 10 is destroyed are expressed by the following equations in both the pushing direction and the pulling direction, as shown in FIG.
x = b · tan45 °
Therefore, L = a + 2b.
In the case of sand, the length b of the internal pressure relief blade 22 and the influence range x in which the ground 10 is destroyed are expressed by the following equations as shown in FIG. + Is the pushing direction and-is the pulling direction.
x = b · tan (45 ° ± φ / 2) (φ = 30 °)
Therefore, L = a + 2.3b.
(8) If the width a of the internal pressure relaxation blade 22 is too small, almost no shear fracture occurs, and if it is too large, the resistance increases, and the purpose of using a large-diameter stirring blade cannot be achieved. In FIG. 2A, the width “a” that satisfies these conditions is set to be equal to or larger than the dimension at which one point A0 of the outer peripheral end of the inner pressure relief blade 22 reaches A1 that is moved by the width “a” when the rotary shaft 14 makes one rotation. desirable.
(9) If the length b of the internal pressure relaxation blade 22 is too long, the resistance increases, the torque also increases, the attachment reinforcement to the rotating shaft 14 as a member also increases, and the inner diameter of the intermediate steady rest 19 passing therethrough. Becomes larger and the steady rest effect is lost. On the other hand, if it is too short, the portion where shear fracture occurs is too small, and the effect of reducing internal pressure becomes small. Therefore, D / 4 ≦ b ≦ D / 2 is desirable. D is the diameter of the rotating shaft 14.

The width a, the length b, and the interval L between the stages satisfying the various conditions as described above are set as follows.
(A) Setting of the width a of the internal pressure reducing blade 22 Based on the above (8), the width a is A1 when the point A0 of the outer peripheral end of the internal pressure relaxing blade 22 is moved by the width a when the rotating shaft 14 makes one rotation. To be more than the dimension to reach
a ≧ β / α
Set with the following formula. β is the penetration speed per unit time, generally 50 to 150 cm / min, and α is the number of rotations per unit time, generally 16 to 20 times / min. For example, when β = 100 and α = 20, a = 5 cm or more is set.
(A) Setting of length b of protrusion of internal pressure relaxation blade 22 Based on (9), the length is set by the following equation.
D / 4 ≦ b ≦ D / 2
The diameter of the rotating shaft 14 is generally 26.7 cm or 31.6 cm. However, if 26.7 cm, 6.7 ≦ b ≦ 13.4 and b ≧ 6.7 cm.
(C) Setting of the attachment interval L of the internal pressure relaxation blades 22 Based on the above (7), L is narrower in the case of clay than in the case of sand. However, since the ground 10 is rarely made of clay or sand, it is desirable to use the narrower L = a + 2b in order to apply to any of them. For example, when a = 15 cm and b = 10 cm, L ≦ a + 2b = 15 + 20 = 35 cm.

  When the ground 10 is agitated by the internal pressure relaxation blades 22 set in this way, in the case of clay, the ground 10 surrounded by diagonal lines is destroyed as shown in FIG. Since the rotating shaft 14 penetrates in the direction of the arrow in the figure, the outer periphery of the rotating shaft 14 is reliably loosened and the internal pressure is relieved. In FIG. 3A, since the internal pressure relaxation blades 22 are attached to the outer periphery of the rotating shaft 14 at an interval of 180 degrees, substantially the same portion of the outer periphery of the rotating shaft 14 is loosened twice. Therefore, the intended purpose can be achieved even with only one of the left and right internal pressure relief blades 22.

  Further, as shown in FIG. 3B, when the ground 10 is sand, the destruction range indicated by oblique lines is wider than that of clay, so that the ground 10 is partially overlapped and destroyed. Also in this example, since the internal pressure relief blades 22 are attached to the outer periphery of the rotating shaft 14 at an interval of 180 degrees, substantially the same portion of the outer periphery of the rotating shaft 14 is loosened twice. Accordingly, the desired purpose can be achieved by using only one of the left and right internal pressure relief blades 22, but the internal pressure may be restored by the adhesive force, so two pairs are preferable.

The results of demonstration tests using the internal pressure relaxation blade of the present invention configured as described above and a deep mixing treatment apparatus using the internal pressure relaxation blade will be described.
The verification test was performed with the conventional specification (1) as shown in FIG. 5 and the four types of specifications (2), (3), and (4) of the present invention.
In FIG. 5, “diameter mm” is the diameter of the rotating stirring blade 16, and the cross-sectional shape and the number of steps are the same. “Compressed air” means that the compressed air that merges with the cement slurry is “Yes” or “No”, and “Internal pressure relief blade” means that the internal pressure relief blade 22 shown in FIG. The “fluid additive” is a fluid additive added to a cement slurry composed of alkali metal carbonate, inorganic chloride, and a polymer dispersant.
As shown in FIGS. 6 (a) and 6 (b), the ground layer 10 is a buried soil having an N value of 8 at a depth of 0 to 5m, a sandy soil having an N value of 20 at a depth of 5 to 10m, and a depth of 10 to 10. 15 m is sandy soil having an N value of 13, 15 to 17 m deep is viscous soil having an N value of 4, and 17 to 20 m deep is viscous soil having an N value of 3.
Moreover, the drive part 17 used the motor of the same specification, and measured the electric current value.

When the penetration test was performed under the above conditions, the result shown in FIG. 6A was obtained.
In the conventional rotating shaft (1) (diameter 1,000 mm, compressed air x, internal pressure relaxation blade x, fluid additive x), the depth is 0 to 5 m, 130 to 230 A, the depth 5 to 10 m, 180 to 300 A, the depth 10 to 10. The ground was 10 to 180 A at 15 m and 120 A at a depth of 15 to 20 m.
In the rotating shaft (2) of the present invention (diameter 1,600 mm, compressed air x, internal pressure relaxation blade O, fluid additive x), the depth is 0 to 5 m, 100 to 150 A, the depth 5 to 10 m, 30 to 130 A, the depth 10 It was 30 to 110 A at ˜15 m, and 120 to 130 A at a depth of 15 to 20 m.
In the rotating shaft (3) of the present invention (diameter 1,600 mm, compressed air ◯, internal pressure relaxation blade ◯, fluid additive ◯), the depth was 20 to 30 A at a depth of 0 to 20 m.
In the rotating shaft (4) of the present invention (diameter 1,600 mm, compressed air ○, internal pressure relaxation blade ○, fluid additive ×, pre-drilled), 30 to 100 A at a depth of 0 to 5 m, 100 A at a depth of 5 to 10 m. The depth was 100 to 120 A at a depth of 10 to 15 m, and 120 to 130 A at a depth of 15 to 20 m.
As described above, it has been found that by providing the internal pressure relaxation blade 22 of an appropriate size on the rotating shaft 14, the stirring resistance value at the time of penetration is greatly reduced even when the diameter becomes large.

Next, at the time of drawing, a result as shown in FIG. 6B was obtained.
The conventional rotating shaft (1) is as high as 170A at the start of drawing at a depth of 20m, but it quickly decreases to 100-70A due to the viscous land, up to a depth of about 20-12m, and a depth of about 12-9m Up to 70-200A, it rises due to the sand ground, and decreases almost linearly to 200-50A up to a depth of about 9-0m.
The rotary shaft (2) of the present invention moves up and down between 150-220A up to a depth of about 20-15m at the start of drawing, changes 150A up to a depth of 15-10m, and rises up to 220A on a 9m deep sand ground. However, after that, it decreases linearly to 50 A by 0 m at which the internal pressure decreases to zero.
The rotating shaft (3) of the present invention is as high as 220A at the start of drawing at a depth of 20m, but immediately decreases to 70A due to the effect of the flow additive, and thereafter reaches 60m to 70m until the depth of 0m where the internal pressure decreases to 0. Transition.
The rotating shaft (4) of the present invention repeats vertical movement between 150 and 220A up to a depth of about 20 to 10 m, and linearly decreases to 50 A from a depth of 10 m to a depth of 0 m.
As described above, by providing the internal pressure relaxation blade 22 of an appropriate size on the rotary shaft 14, although not as much as when penetrating, there is a large change in the stirring resistance value at the time of drawing with the conventional small diameter and the large diameter of the present invention. Not found out.

The arrangement of the internal pressure relief blades 22 is not limited to the case of FIG. 2A, and may be attached as shown in FIG. 2B or FIG.
That is, in FIG. 2 (b), the pressure relieving blade 22 at intervals of a central angle of 120 degrees, and are those arranged in multiple stages in a spiral at intervals of sequential L, also, and FIG. 2 (c) Shows an example in which the rotating shaft 14 is arranged with a predetermined angle θ with respect to the center line. This angle θ may be the penetration angle of the rotating shaft 14 or may be other than that. Further, the width a of the internal pressure relaxation blade 22 may be increased according to the numerical value of β / α when the penetration speed β per unit time is large and the rotational speed α per unit time is small.

  In the embodiment of FIG. 1, the case where the rotary shaft 14 is a single-shaft type has been described. However, as shown in FIGS. It is good also as a biaxial type arrange | positioned with the space | interval x. The two rotary shafts 14 are connected at the upper, middle, and lower stages by a base steadying portion 18 to maintain the position.

Conventionally, the stirring blade 16 in the above example is a trapezoid whose both side surfaces are inclined as shown in FIG. The bottom surface may be horizontal and attached to the rotating shaft 14.
This is to prevent a large resistance from being applied to the rotation drive unit 17 for rotating the rotating shaft 14.
As a result of the demonstration test using the rotary shaft 14 with the conventional stirring blades attached to the sand ground and the rotary shaft 14 with the trapezoid blades of the present invention, characteristic results as shown in FIG. 7A were obtained.
When φ = 1,000 mm with the conventional rotating shaft 14 (1) of a 45 ° inclined plate, the maximum penetration force at the time of penetration is 400 N · m, and the maximum penetration force at the time of withdrawal is −700 N · m. Met.
When the rotary shaft 14 (2) to which the trapezoidal wing of the present invention is attached and φ = 1200 mm, the maximum penetration force at the time of penetration is 500 N · m, and the maximum penetration force at the time of withdrawal is −400 N · m. It was.
When the rotary shaft 14 (3) to which the trapezoidal wing of the present invention is attached and φ = 1,300 mm, the maximum penetration force at the time of penetration is 600 N · m, and the maximum penetration force at the time of withdrawal is −600 N · m. Met.
When the rotation shaft 14 (4) to which the trapezoid of the present invention is attached and φ = 1500 mm, the maximum penetration input at the time of penetration is 750 N · m, and the maximum penetration input at the time of withdrawal is −750 N · m. there were.
From the above results, the conventional φ = 1,000 mm and the present invention φ = 1,200 mm are substantially equal when penetrating, and the conventional φ = 1,000 mm and the present invention φ = 1,500 mm are substantially equal when pulled out. It turns out that they are equal.

The rotating shaft 14 of the present invention is not limited to the trapezoidal shape shown in FIG. 7 (b), and may be a semicircular shape as shown in FIG. 7 (c) or a semi-elliptical shape as shown in FIG. 7 (d). The same effect can be obtained.
As described above, according to the present invention, in addition to the effect of attaching the internal pressure reducing blade, the effect of reducing the resistance at the time of penetration and at the time of drawing can be obtained by making the stirring blade a trapezoidal section or the like.

  In the present invention, the fluidity of the cement slurry is increased and a fluid additive that fluidizes the soil immediately after mixing is mixed and sprayed. As shown in FIG. 7, when the blade width of the stirring blade 16 is small, disturbance of stirring and mixing is difficult to occur, and problems in mixing efficiency are likely to occur. Therefore, a fluid flow additive having fluidity can be used to eliminate the adverse effects. In order to ensure the good quality of the deep mixing process improvement body, the penetration / drawing speed per minute of the mixing processing machine, the number of stages of the stirring blade, the number of rotations, and the like have been performed to satisfy certain standard values. However, even if the standard value is lowered by using a fluid additive, the quality of the same improved body is ensured, the construction efficiency is expected to be significantly increased, and the construction cost can be reduced. Yes.

In the present invention, compressed air can be mixed and injected into a cement slurry.
Compressed air is mixed into the cement slurry for penetration of hard sandy ground, causing plastic breakage of the ground to assist the penetration of the processing machine, and adhesion resistance by compressed air even when the viscous soil layer is pulled out Reduce. The compressed air supplied to the ground together with the cement slurry is transmitted to the ground surface from the periphery of the rotating shaft through the ground loosened by the internal pressure relief blades disposed on the outer peripheral portion of the rotating shaft. Compressed air does not stay in the ground or the surrounding soil during creation, and is discharged to the ground surface, so it does not adversely affect the improved body.
The internal pressure relief blades are attached to the rotary shaft at a pitch of 25 cm to 50 cm, and are quickly discharged to the ground surface along the loosened ground generated as the rotary shaft rotates. Even in that case, the fluidity of the mixture which has not yet solidified is required, and the effect of using a fluid additive is further increased.

DESCRIPTION OF SYMBOLS 10 ... Ground, 11 ... Base machine, 12 ... Leader, 13 ... Stay, 14 ... Rotating shaft, 15 ... Excavation blade, 16 ... Stirring blade, 17 ... Drive part, 18 ... Base steadying part, 19 ... Intermediate steadying part 20 ... Cement slurry injection pipe, 21 ... Air injection pipe, 22 ... Internal pressure relief blade, 23 ... Cement slurry discharge port, 24 ... Air jet outlet, 25 ... Solidification improvement body, 26 ... Upper support part.

Claims (12)

While rotating the rotating shaft having the excavating blade and the agitating blade at the tip, it penetrates and withdraws into the ground, discharges the cement slurry from the tip of the rotating shaft, and stirs and mixes the ground to construct a solidified improved body In the deep mixing processing equipment
A multistage internal pressure relief blade that loosens the ground around the rotation shaft and relieves earth pressure applied to the rotation shaft above the stirring blade in the rotation shaft, the width direction of which is substantially the same as the axial direction of the rotation shaft. A deep mixing treatment apparatus characterized in that the internal pressure relief blades are provided so as to satisfy the following conditions.
L ≦ a + 2b
a ≧ β / α
D / 4 ≦ b ≦ D / 2
Where D: diameter of the rotating shaft a: width of the inner pressure relaxing blade b: length of the inner pressure relaxing blade L: interval between the inner pressure relaxing blades on the rotating shaft β: penetration speed per unit time of the rotating shaft α: of the rotating shaft Number of revolutions per unit time   2. The deep mixing apparatus according to claim 1, wherein at least one internal pressure relief blade is provided for each stage.   The deep mixing treatment apparatus according to claim 1, wherein the internal pressure relaxation blades are arranged in a spiral shape with a center angle of each stage shifted by a predetermined angle. Pressure relieving wing with a central angle providing two shifted 180 degrees to each stage, Deep Mixing apparatus according to claim 2, characterized in that provided by shifting the central angle of 90 degrees above and below the stage.
  5. The deep mixing apparatus according to claim 4, wherein two internal pressure relief blades each having a central angle shifted by 180 degrees on each stage are arranged on a line orthogonal to the axial direction of the rotating shaft.   5. The deep mixing process according to claim 4, wherein the two internal pressure relief blades provided with the central angle shifted by 180 degrees at each stage are arranged on a line intersecting with the axial direction of the rotating shaft at an angle other than 90 degrees. apparatus.   2. The deep mixing apparatus according to claim 1, wherein the stirring blade has a trapezoidal longitudinal section.   The deep mixing apparatus according to claim 1, wherein the stirring blade has a semicircular or semi-elliptical longitudinal section.   2. The deep mixing apparatus according to claim 1, wherein the cement slurry is injected with compressed air mixed therein.   2. The deep mixing apparatus according to claim 1, wherein the cement slurry is discharged by mixing a fluid additive that enhances the fluidity of the cement slurry and fluidizes the soil immediately after mixing.   2. The deep mixing apparatus according to claim 1, wherein the rotating shaft is a single-shaft type.   2. The deep mixing apparatus according to claim 1, wherein the rotating shaft is a multi-shaft type.

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