JP2005350871A - Three-shaft deep mixing method of soil stabilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-shaft deep mixing method of soil stabilization, which enables soil and a solidification material to be surely and efficiently agitated and mixed. <P>SOLUTION: Three rotating shafts 1, the leading ends of which are equipped with agitating blades 4, are juxtaposed. A spiral 6, which pushes surrounding soil upward when the rotating shaft is normally rotated in penetration and which pushes the surrounding soil downward when the rotating shaft is counterrotated in extraction, is provided only on the outer peripheral surface of the central rotating shaft 1b. The push-up and push-down of the soil by the spiral make soil pressure in the central part of an agitating area 5 deceased in the penetration/increased in the extraction, so that the horizontal flow of improved soil in the agitating area can be accelerated. The solidification material is supplied only from the two rotating shafts 1a on both sides. The rotating shafts 1a on both the sides among the three rotating shafts are rotated in the same direction, and the central rotating shaft 1b is rotated in a direction opposite to the rotational direction of the rotating shafts 1a, so that a series of agitating flows, such that the improved soil continuously flows throughout the agitating area 5, can be formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a triaxial deep mixing processing apparatus having a three-axis rotation shaft, and a triaxial deep mixing processing method that is a ground improvement method using the triaxial deep mixing processing method.

  As this type of triaxial deep-mixing processing apparatus, there is one disclosed in, for example, Patent Document 1, but the basic configuration thereof is as shown in FIG. Are rotated in opposite directions by independent drive sources 2, and the central rotating shaft 1b is rotated in the same direction as one of the rotating shafts 1a on both sides via the power transmission device 3 (and therefore in the opposite direction to the other). It is.

  In the conventional three-axis deep mixing processing method using such a three-axis deep mixing processing apparatus, each rotary shaft 1 is rotated forward and the ground is stirred by each stirring blade 4 so that the whole penetrates into the ground to a predetermined depth. After that, each rotary shaft 1 is reversely rotated and pulled out. During such an intrusion process or pull-out process, a solidified material such as cement slurry or cement powder is ground into the ground from the tip of each rotary shaft 1. It is made into improved soil by being stirred and mixed with the soil of the original ground, and the ground is improved by curing it.

Further, although not based on a three-axis rotating shaft, as a ground improvement method for supplying a solidified material to the ground and stirring and mixing, for example, Patent Document 2 and Patent Document 3 include soil corresponding to the amount of solidified material supplied. A method has also been proposed in which the amount of soil is positively discharged to prevent the soil from expanding due to the supply of the solidified material and to avoid the deformation of the surrounding ground.
Japanese Patent No. 3156043 Japanese Patent Publication No. 5-62167 Japanese Patent No. 3094266

  By the way, in the conventional triaxial deep-mixing treatment apparatus as shown in Patent Document 1 and the triaxial deep-mixing treatment method using the conventional triaxial deep-mixing treatment method, the three-spindle as shown in FIG. The agitation zone 5 is formed, and the solidified material and the soil of the original ground are agitated and mixed there. However, the agitation and mixing in the agitation zone 5 is not necessarily sufficiently performed, and the intended improvement effect is achieved. It is also assumed that cannot be obtained. In particular, in the conventional general triaxial deep-mixing treatment apparatus, the rotation direction of the central stirring blade 4 always rotates in the same direction as one of the stirring blades 4 on both sides. As shown in the figure, a moderate stirring effect can be expected between the two rotating in the opposite direction, but the flow of the improved soil is divided between the two rotating in the same direction, and the improved soil is stagnated there. Therefore, it has been pointed out that there may be a bias in the stirring and mixing state of the solidified material and the soil in the stirring region 5.

  In addition, in the case of performing soil removal as shown in Patent Document 2 and Patent Document 3, it is necessary to strictly control the amount of soil discharged so as to match the supply amount of the solidifying material. It is not always easy to do.

  In view of the above circumstances, the present invention provides a three-axis deep layer mixing treatment apparatus that enables more reliable and efficient stirring and mixing of soil and solidified material in a triple stirring region formed by three rotating shafts. It is an object of the present invention to provide a three-axis deep mixing method.

  According to the first aspect of the present invention, the tip of the rotating shaft is arranged while three rotating shafts having a stirring blade at the tip are juxtaposed, and the rotating shafts are rotated forwardly to penetrate into the ground and reversely pulled out. A three-axis deep mixing processing apparatus configured to improve the ground by supplying a solidification material from the section into the ground and stirring and mixing in a triple stirring region formed by each stirring blade. The outer peripheral surface is provided with a spiral that pushes up the surrounding soil upward during forward rotation during penetration and pushes down the surrounding soil downward during reverse rotation during extraction.

  The invention of claim 2 is a triaxial deep mixing method for improving the ground by the triaxial deep mixing treatment apparatus of the invention of claim 1, wherein each rotating shaft is rotated forward to penetrate into the ground. However, by pushing up the surrounding soil upwards by the spiral formed on the central rotating shaft, the earth pressure at the central portion of the stirring region by these three rotating shafts is lowered from both sides, so that the center from both sides of the stirring region The soil pressure at the center of the agitation zone is reduced by pushing down the surrounding soil downward by the spiral when the shaft is pulled out from the ground by rotating the rotating shafts in the reverse direction. It is characterized by promoting the flow of improved soil from the central part of the agitation zone toward both sides by raising it from both sides.

  A third aspect of the invention is the three-axis deep mixing method according to the second aspect of the invention, wherein the solidification material is supplied only from the two rotary shafts on both sides of the three rotary shafts.

  The invention of claim 4 is the three-axis deep mixing processing method of the invention of claim 2 or 3, wherein the rotary shafts on both sides of the three rotary shafts are rotated in the same direction and the central rotary shaft is set on both sides. By rotating in the direction opposite to the rotation axis, a series of stirring flow in which the improved soil continuously flows over the entire stirring region is formed.

  According to the three-axis deep mixing processing method using the three-axis deep mixing processing apparatus of the present invention, the surrounding soil is pushed upward by the spiral provided on the central rotating shaft at the time of penetration. The earth pressure of the part is relatively lower than both sides, thereby promoting the flow of the improved soil from both sides of the stirring area toward the central part, and effectively stirring and mixing the entire stirring area. Conversely, when pulling out, the surrounding soil is pushed downward by the spiral, so that the earth pressure in the central part of the stirring area rises relative to both sides, so that the central part of the stirring area moves from the central part to both sides. The flow of the improved soil is promoted, and the stirring and mixing in the entire stirring area is effectively promoted. Therefore, according to the present invention, the solidified material and the soil are sufficiently stirred and mixed over the entire triple stirring region by the three-axis rotating shaft, and an excellent ground improvement effect is obtained.

  In the present invention, the supply of the solidifying material is arbitrary. For example, the solidifying material may be supplied from all three axes or from the central one axis. However, the solidifying material may be supplied only from the two axes on both sides. If performed, the solidified material supplied at the time of intrusion will naturally spread over the entire stirring region on the improved soil flow from both sides to the center as described above, and an excellent stirring and mixing effect is obtained. . In addition, if the solidifying material is supplied only from two shafts, the solidifying material supply mechanism and supply equipment in the conventional two-shaft stirring and mixing processing apparatus can be diverted as it is, so that also in terms of equipment costs and management costs. It is advantageous.

  In addition, the setting of the rotation direction of the three rotation shafts may be the same as the conventional one, but by rotating the rotation shafts on both sides in the same direction and rotating the central rotation shaft in the opposite direction, This is more effective because a series of stirring flows are formed such that the improved soil continuously flows over the entire three stirring regions by the stirring blades.

  One embodiment of the present invention is shown in FIGS. FIG. 1 is a schematic configuration diagram showing a basic configuration of a triaxial deep-mixing treatment apparatus of the present embodiment. This is similar to a conventional triaxial deep-mixing treatment apparatus, in which a triaxial rotating shaft 1 is arranged in parallel. A plurality of (four in the illustrated example) stirrer blades 4 are provided at the tip of the rotary shaft 1, but a spiral 6 is formed on the outer peripheral surface of the central rotary shaft 1b of the three rotary shafts 1. doing. The spiral 6 may be provided over the entire length of the rotary shaft 1b at a pitch of, for example, about 400 mm above the uppermost stirring blade 4 or partially at a key point. In some cases, the surrounding soil is pushed upward, and the surrounding soil is pushed downward during reverse rotation during extraction. The tip of each rotary shaft 1 is provided with discharge ports 9 and 10 for the solidified material in the vicinity of the lowermost stirring blade 4 and the uppermost stirring blade 4, respectively. The discharge is basically performed from the discharge port 9 on the side, and the solidified material is discharged from the discharge port 10 on the upper stage side at the time of drawing.

  Further, in the three-axis deep mixing processing apparatus of the present embodiment, each rotary shaft 1 is independently driven by a dedicated drive source 2, and the rotation directions thereof are forward rotation at the time of penetration and reverse rotation at the time of extraction. At any time, as shown in the drawing, the rotating shafts 1a on both sides rotate in the same direction and the central rotating shaft 1b rotates in the opposite direction (that is, the three rotating shafts 1a, 1b, 1a alternately rotate in the opposite direction).

  By setting the rotation direction of each rotating shaft 1 in such a manner, in the three-axis deep mixing processing apparatus of the present embodiment, as shown in FIGS. 2 (a) and 2 (b), both at the time of penetration and at the time of withdrawal. Thus, a series of stable stirring flows are formed so that the improved soil continuously flows over the entire three stirring regions 5, and one of the stirring regions 5 is formed as in the conventional case shown in FIG. Thus, the flow of the improved soil is not interrupted in the part, and thereby the solidified material and the soil can be reliably and efficiently stirred and mixed throughout the stirring region 5.

  Furthermore, in the three-axis deep-mixing processing apparatus of this embodiment, the stabilizer 8 is installed in three stages so as to be inclined with respect to the direction on the line connecting the rotary shafts 1 between the lower end portions of the rotary shafts 1. Thus, the series of stirring flows as described above in the stirring region 5 is more reliably and efficiently generated by the stabilizers 8. That is, as shown in FIG. 3, the two-stage connecting member 7 that connects the lower portions of the respective rotary shafts 1 includes an upper portion of the upper connecting member 7 and an upper portion and a lower portion of the lower connecting member 7. Each plate-like stabilizer 8 is fixed in a state of being inclined with respect to the length direction of the connecting member 7 as shown in FIGS. 4 (a) and 4 (b). And the direction (installation direction) of these stabilizers 8 is the direction along the stirring flow from both sides to the central part at the time of forward rotation at the time of penetration as shown in FIG. 5 (a) (therefore stirring from the central part to both sides). It is set in the direction crossing the flow).

  By providing such a stabilizer 8, as shown in FIG. 5 (a), the stirring flow in the direction from the outside toward the center portion smoothly flows without stagnation while being guided by the stabilizer 8 at the time of penetration. The stir flow in the direction from the center to the outside is blocked by the stabilizer 8, so that the stir flow toward the outside as indicated by the wavy arrow as compared to the stir flow toward the center as indicated by the solid arrow. Is to be suppressed. Similarly, at the time of pulling out in which the rotation directions of the rotary shafts 1 are reversed, as shown in FIG. 5B, the stirring flow in the direction from the center to the outside is guided smoothly by the stabilizer 8 without stagnation. However, the stirring flow in the direction from the outside toward the center is blocked by the stabilizer 8, thereby suppressing the stirring flow toward the center compared to the stirring flow toward the outside.

  Specific steps of the triaxial deep-mixing processing method using the triaxial deep-mixing processing apparatus configured as described above are shown in FIGS. First, as shown in FIG. 6A, each rotary shaft 1 is rotated forward to penetrate into the ground. At this time, the solidifying material is supplied only from the discharge port 9 provided in the vicinity of the lowermost stirring blade 4 of the rotating shaft 1a on both sides.

  Thereby, in the triple stirring region 5 formed by each stirring blade 4, in addition to the continuous series of stirring flows as described above, the surrounding soil is naturally pushed upward by the spiral 6. Therefore, the earth pressure in the central part of the stirring area 5 is naturally relatively lower than the earth pressure on both sides, and since the solidifying material is supplied only on both sides of the stirring area, the earth pressure on both sides is reduced in the central part. As shown by the white arrow in FIG. 6 (b), the stir flow toward the center is further accelerated by the stabilizer 8 compared to the stir flow toward the outside. The flow of the improved soil that flows from both sides toward the center is naturally promoted, whereby the agitation and mixing are promoted over the entire agitation region 5, and a sufficient agitation and mixing effect is obtained.

  In addition, as shown in FIGS. 7 (a) and 7 (b), the rotating shafts 1 are rotated in the reverse direction as shown in FIGS. 7 (a) and 7 (b). Therefore, contrary to the above, the surrounding soil is naturally pushed downward by the spiral 6. Since the earth pressure in the central part of the stirring region 5 naturally rises relative to the earth pressure on both sides, the stir flow toward the outside is promoted by the stabilizer 8 as compared with the stirring flow toward the central part. Thus, the flow of the improved soil flowing toward both sides is naturally promoted, and the agitation and mixing are promoted over the entire agitation region 5 as in the case of penetration, and a sufficient agitation and mixing effect is obtained. The solidified material is supplied at the time of drawing from the discharge port 10 provided in the vicinity of the uppermost stirring blade of the rotary shaft 1a on both sides.

  As described above, according to the triaxial deep layer mixing treatment apparatus of the present embodiment and the triaxial deep layer mixing treatment method using the triaxial deep layer mixing treatment apparatus, the push-up action at the time of penetration by the spiral 6 provided mainly on the outer peripheral surface of the central rotating shaft 1b, and the drawing time By the pushing-down action in the horizontal direction, the flow of the improved soil in the horizontal direction is naturally promoted in the entire three stirring regions 5 by the respective stirring blades 4, and thereby the solidified material and the soil are reliably and efficiently stirred and mixed without deviation. A significant ground improvement effect can be obtained.

  FIG. 8 shows test results for performance comparison between the triaxial deep-mixing treatment apparatus (this machine) of the above embodiment and a conventional general biaxial deep-mixing treatment apparatus (conventional machine). This is a measurement of the needle penetration strength of the improved ground for each material age. (A) is the case where the solidification material mixing rate is 10% and (b) is the case where it is 15%. This is an example in which the machine is supplied from only two axes on both sides and the conventional machine is supplied from both of the two axes. As is apparent from FIG. 8, the strength of the improved soil is increased from the early stage compared to the conventional device, and it has been demonstrated that an excellent ground improvement effect can be obtained.

  Since the spiral 6 as described above is provided on the outer peripheral surface of the rotary shaft 1 having the stirring blade 4 at the tip, the exhaust configuration as shown in Patent Document 2 described above is used in the installation mode. It may be considered that it is common with a soil screw or a propeller-shaped earth discharging blade as disclosed in Patent Document 3. However, the screw and soil removal blades in these Patent Documents 2 and 3 are intended to prevent ground expansion by positively soiling the amount of soil corresponding to the supply amount of the solidifying material at the time of extraction. On the other hand, the spiral 6 of this embodiment is for the purpose of improving the stirring and mixing efficiency in the stirring region, not simply for discharging soil, and pushes up and pushes down the surrounding soil when penetrating. In order to efficiently promote the horizontal movement of the improved soil in the agitation zone, the functions required for the spiral 6 and its specific configuration are the same as the screw and the earth discharging blade in Patent Documents 2 to 3. Needless to say, it is completely different.

  Although one embodiment of the present invention has been described above, the above embodiment is merely an example, and the present invention pushes up the soil at the time of penetration by the spiral 6 provided on the central rotating shaft 1b and pushes down the soil at the time of pulling out. As long as it is configured as described above, various applications and changes such as those listed below are possible for the configuration and specific steps of each part.

  The rotation directions of the three rotation shafts 1 are preferably set so as to be alternately opposite to each other as in the above-described embodiment. However, the above-described mechanism is sufficient only by providing the spiral 6 on the central rotation shaft 1b. Therefore, it is not necessarily configured as described above, and the rotation direction of each rotary shaft 1 may be the same as the conventional one. In any case, not only an electric motor but also a hydraulic motor or other drive source can be adopted as the drive source 2 for each rotary shaft 1, and the three-axis rotary shaft 1 is only driven by an independent drive source 2. Of course, it may be driven through the power transmission mechanism 3 as in the conventional case.

  Similarly, although it is preferable to provide the stabilizer 8 so that a series of stirring flows is reliably generated over the entire stirring region 5 as in the above embodiment, the stabilizer 8 is not essential. Also, when the stabilizer 8 is provided, the position and direction may be set so that a preferable stirring flow is generated in each step in consideration of the rotation direction of each rotary shaft 1 at the time of penetration or withdrawal. It is also conceivable that the stabilizer 8 provided on the lower side and the stabilizer 8 provided on the lower side are provided in opposite directions so that a stirring flow toward the center and an agitation flow toward the outside are simultaneously generated above and below the stirring region.

  The supply of the solidified material is not limited to being performed from only two axes on both sides as in the above embodiment, but may be performed from all of the three rotation shafts 1 or only from the central one axis. It is also possible to switch the supply axis appropriately during the process or to change the supply amount every moment. The supply timing of the solidified material may be appropriately performed only at the time of penetration, only at the time of withdrawal, or at the time of penetration and at the time of withdrawal. In addition, the solidifying material discharge ports 9 and 10 are not limited to two at the tip of each rotary shaft 1 as in the above embodiment, and the discharge ports are appropriately provided at necessary positions on the necessary rotation shafts. It ’s fine. In the present invention, for example, as shown in FIGS. 6 to 7, in response to the flow of improved soil generated at the time of penetration and withdrawal, the soil is supplied from the rotary shafts 1 a on both sides at the time of penetration, and the central rotary shaft 1 b at the time of withdrawal. It is conceivable to switch to the supply from the soil, and in this way, the difference in the improved earth pressure between the central part and both sides and the flow of the improved earth accompanying it more remarkably occur, and the necessary minimum solidified material can be supplied to the entire stirring area. More efficiently. However, switching the supply shaft as described above requires a mechanism and operation for that purpose, and therefore, the supply shaft can be supplied only from the biaxial rotating shaft 1a at both the penetration time and the withdrawal time as in the above embodiment. It is the most realistic, and it is possible to obtain a sufficient effect. In that case, the solidification material supply mechanism and the supply equipment in the conventional biaxial stirring and mixing processing apparatus can be diverted as it is. Therefore, it is advantageous in terms of equipment costs and management costs.

  In any case, it is preferable to supply the solidifying material from the forefront of the rotating shaft 1 at least during penetration, and it is preferable to immediately stir the solidified material supplied from the rotating shaft 1 with the stirring blade 4. The lower stirring blade 4 is preferably provided at the most distal end of the rotating shaft 1 as much as possible. Therefore, when it is assumed that the solidification material is supplied from the lower discharge port 9 of the biaxial rotating shaft 1a at the time of penetration as in the above embodiment, the biaxial biaxial as shown in FIG. It is preferable that the lowermost stirring blade 4 on the rotating shaft 1a is installed at the most distal portion, and the lowermost stirring blade 4 on the central rotating shaft 1b is installed on the upper side. On the other hand, if the supply of the solidified material from the central rotating shaft 1b is the main, the lowermost stirring blade 4 of the central rotating shaft 1b is installed at the foremost part and the outermost rotating shafts 1a on both sides are installed. What is necessary is just to install the lower stirring blade 4 above it.

  Further, in the present invention, it is conceivable to adjust the rotation speed and torque of each rotary shaft 1 according to various conditions such as the ground condition. That is, if the rotational speed of the rotary shaft 1 is increased, the improved earth pressure is further increased. Therefore, at the time of penetration as shown in FIG. 6, the rotational speeds of the rotary shafts 1a on both sides are set larger than the rotational speed of the central rotary shaft 1b. By doing so, the soil pressure on both sides in the agitation region can be further increased, and the flow of improved soil toward the center can be generated more remarkably. Similarly, at the time of pulling out as shown in FIG. 7, by setting the rotational speed of the central rotating shaft 1b to be larger than the rotational speed of the rotating shafts 1a on both sides, the earth pressure at the central portion is further increased, and the flow toward both sides is further increased. It can be remarkably generated. In addition, in the triaxial deep mixing processing method as in the present embodiment, depending on the ground situation, it may be assumed that there is a difference in the load applied to each rotary shaft 1, so when such a load imbalance occurs, Reducing the rotational speed of the rotating shaft to which the high load is applied to increase the torque, and relatively increasing the rotational speed of the low-load rotating shaft to decrease the torque, thereby reducing the rotational shaft 1. Torque can be adjusted appropriately according to the load, and the optimum operation according to the ground condition becomes possible.

It is a figure which shows schematic structure of the triaxial deep-layer mixing processing apparatus which is embodiment of this invention. It is a figure which shows the basic stirring flow in a series of stirring area | region similarly. It is a figure which shows the specific structural example of the same 3 axis | shaft of rotating shaft. It is sectional drawing which shows the installation state of a stabilizer similarly. It is a figure which shows the stirring state in a stirring area | region similarly. It is a figure which shows the process at the time of penetration of the triaxial deep-layer mixing processing method which is embodiment of this invention. It is a figure which shows the process at the time of extraction similarly. It is a figure which shows the verification test result of a ground improvement effect same as the above. It is a figure which shows schematic structure of the conventional triaxial deep-layer mixing processing apparatus. It is a figure which shows the stirring state in a stirring area | region similarly.

Explanation of symbols

1 (1a, 1b) Rotating shaft 2 Drive source 4 Stirring blade 5 Stirring area 6 Spiral 7 Connecting member 8 Stabilizer 9, 10 Discharge port

Claims (4)

Three rotating shafts equipped with a stirring blade at the tip are arranged side by side, and these rotating shafts are rotated forward to penetrate into the ground and reversely rotated while being pulled out, while solidifying from the tip of the rotating shaft into the ground. A three-axis deep mixing treatment device configured to improve the ground by stirring and mixing in a triple stirring region formed by each stirring blade,
A triaxial deep mixing process characterized in that a spiral is provided on the outer peripheral surface of the central rotating shaft to push up the surrounding soil upward during forward rotation during penetration and to push down the surrounding soil downward during reverse rotation during withdrawal apparatus. A triaxial deep mixing treatment method for ground improvement by the triaxial deep mixing treatment apparatus according to claim 1,
By rotating each rotating shaft forward and penetrating into the ground, the surrounding soil is pushed upward by a spiral formed in the central rotating shaft, so that the soil at the center of the stirring region by these three rotating shafts Reduce the pressure from both sides to promote the flow of improved soil from both sides of the agitation zone to the center, and when rotating each rotating shaft backwards and pulling it out from the ground, the surrounding soil is lowered by the spiral. A triaxial deep-mixing processing method characterized in that by pushing down, the earth pressure at the central portion of the stirring region is raised from both sides to promote the flow of improved soil from the central portion of the stirring region toward both sides. A triaxial deep mixing method according to claim 2,
A three-axis deep mixing method, characterized in that the solidifying material is supplied only from two rotary shafts on both sides of the three rotary shafts. A triaxial deep mixing method according to claim 2 or 3,
By rotating the rotary shafts on both sides of the three rotary shafts in the same direction and rotating the central rotary shaft in the opposite direction to the rotary shafts on both sides, a series of improved soil flows continuously throughout the stirring region. A triaxial deep mixing method characterized by forming a stirring flow.

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