JP4370204B2 - Triaxial deep mixing method - Google Patents

Description

  The present invention relates to a three-axis deep mixing treatment method that is a ground improvement method using a three-axis deep mixing treatment apparatus having a three-axis rotation shaft.

  As this type of three-axis deep mixing method, for example, there is one disclosed in Patent Document 1, but as shown in FIG. 4, the two rotary shafts 1a on both sides of the three rotary shafts 1 are independent of each other. 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 thus in the opposite direction). is there.

In the conventional three-axis deep mixing processing method, each rotary shaft 1 is rotated forward and the ground is stirred by each stirring blade 4 so that the whole is penetrated into the ground to a predetermined depth. It is pulled out by rotating in reverse, but solid materials such as cement slurry and cement powder are supplied into the ground from the tip of each rotating shaft 1 in the middle of such penetration process and drawing process. The soil is improved by stirring and mixing, and the ground is improved by curing it.
Japanese Patent No. 3156043

  By the way, in the conventional three-axis deep mixing method, the three stirring regions 5 as shown in FIG. 5 are formed by the respective stirring blades 4 of the three-axis rotating shaft 1, and the solidified material and the soil of the original ground there. However, there may be a case where the stirring and mixing in the stirring region 5 is not always sufficiently performed and the desired improvement effect cannot be obtained. In particular, in the prior art, 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, so that it rotates in the opposite direction as shown in FIGS. 5 (a) and 5 (b). A moderate agitation effect can be expected between the two to be operated, but the flow of the improved soil is interrupted between the two rotating in the same direction, so that the improved soil stagnates and thereby the stirring region 5 It has been pointed out that bias may occur in the stirring and mixing state of the solidified material and the soil.

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

  According to the first aspect of the present invention, there are provided three rotating shafts each having a stirring blade at the tip, and the rotating shafts are rotated forwardly to penetrate into the ground and reversely rotated and pulled out from the ground. A three-axis deep mixing method for improving the ground by supplying solidified material from the tip of the ground into the ground and stirring and mixing in a triple stirring region formed by each stirring blade. The rotating shafts on both sides are rotated in the same direction, and the central rotating shaft is rotated in the opposite direction to the rotating shafts on both sides, thereby forming a series of stirring flow in which the improved soil continuously flows over the entire stirring region. In addition, by making a difference between the rotational speeds of the rotary shafts on both sides and the rotational speed of the central rotary shaft, a difference is caused in the improved earth pressure between the both sides and the center of the stirring region. To promote the flow of improved soil One in which the.

  According to a second aspect of the present invention, in the triaxial deep mixing method according to the first aspect of the invention, the supply amount of the solidified material from the rotation shaft is set according to the rotation speed, and the supply amount from the rotation shaft having a higher rotation speed is set. The rotation amount is set larger than the supply amount from the rotation shaft.

  According to a third aspect of the present invention, in the three-axis deep mixing method according to the first aspect of the invention, the rotational speed of the rotary shaft is set in accordance with the load, and the rotational speed of the high-load rotary shaft is set to rotate the low-load rotary shaft. It is set smaller than the number.

  According to the first aspect of the present invention, basically, by setting the rotation direction of each rotating shaft as described above, a series of such that the improved soil continuously flows over the entire triple stirring region by each stirring blade. A stir flow is naturally formed, and thus the stir flow is not divided in a part of the stir zone as in the prior art, and the improved soil does not stagnate there, and a more reliable and efficient stir and mix effect is obtained. Obtained, and an excellent ground improvement effect is obtained. Moreover, by making a difference between the rotational speeds of the rotating shafts on both sides and the rotational speed of the central rotating shaft, a natural difference is caused in the improved earth pressure between the both side portions and the central portion of the stirring region. The flow of the improved soil such that the improved soil moves in the horizontal direction is naturally promoted, and the stirring and mixing effect can be further enhanced.

  According to the second aspect of the present invention, the amount of solidification material supplied from the rotating shaft is set corresponding to the rotational speed, and the amount supplied from the rotating shaft having a large rotational speed is increased to increase the supplied solidification. As described above, the material can be efficiently spread over the entire stirring region by being put on the flow of the improved soil that moves in the horizontal direction, and excellent stirring and mixing efficiency can be obtained.

  Further, according to the third aspect of the present invention, when there is a difference in the load applied to the rotary shafts on both sides and the central rotary shaft due to the ground condition or the like, the rotational speed of the rotary shaft to which a high load is applied is reduced. By making it smaller than the number, each torque can be adjusted according to the load, which makes it possible to optimally operate according to the ground condition, and at the same time, by making a difference in the rotation speed as described above Excellent stirring and mixing efficiency can be obtained at the same time.

  One embodiment of the present invention is shown in FIGS. As shown in FIG. 1, in the three-axis deep mixing processing method of this embodiment, a plurality of stages (four stages in the illustrated example) of stirring blades 4 are respectively provided at the tip of the three-axis rotating shaft 1 arranged in parallel as in the prior art. Using the three-axis deep mixing processing apparatus having the structure provided, the stirring blades 4 form the three stirring regions 5 as shown in FIG. 2, and the soil and solidified material of the original ground are stirred and mixed there. In the three-axis deep mixing method according to the present embodiment, each rotary shaft 1 is driven independently by a dedicated drive source 2 and the rotation direction thereof is determined at the time of penetration. In both the forward rotation and the reverse rotation at the time of extraction, as shown in the drawing, the rotary shafts 1a on both sides rotate in the same direction and the central rotary shaft 1b rotates in the opposite direction (that is, The three rotating shafts 1a, 1b, 1a rotate alternately in the opposite direction. To) it is assumed.

  By setting the rotation direction of each rotary shaft 1 in such a manner, the improved soil is continuously spread over the entire three stirring regions 5 at the time of penetration and at the time of withdrawal as shown in FIGS. 2 (a) and 2 (b). As a result, a flow of agitated flow is formed, so that the flow of the improved soil is divided and stagnated in a part of the agitated region 5 as in the conventional case shown in FIG. Accordingly, the solidified material and the soil can be reliably and efficiently stirred and mixed over the entire stirring region 5 without deviation. The tip of each rotating shaft 1 is provided with solidifying material discharge ports 9 and 10 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.

  In addition to the above, in the three-axis deep mixing processing method of the present embodiment, the difference between the rotational speed of the rotary shaft 1a on both sides and the rotational speed of the central rotary shaft 1b is set, so A difference in the improved earth pressure is generated between the two parts, thereby promoting a flow in which the improved earth moves in the horizontal direction in the stirring region 5.

  That is, for example, as shown in FIG. 3 (a), by setting the rotational speed of the central rotating shaft 1b to be larger than the rotational speeds of the rotating shafts 1a on both sides, the improved earth pressure at the central portion of the stirring region 5 is increased on both sides. Rather, the flow of the improved soil is promoted such that the improved soil flows from the central portion toward both sides. On the contrary, as shown in FIG. 3B, the improved earth pressure on both sides of the stirring region 5 is set at the central portion by setting the rotational speed of the rotary shaft 1a on both sides to be larger than the rotational speed of the central rotary shaft 1b. Rather, the flow of the improved soil is promoted so that the improved soil flows from both sides toward the center. Note that if the rotational speed of the rotary shaft 1 is increased, the torque will naturally decrease, and if the rotational speed is decreased, the torque will naturally increase.

  According to the present embodiment, in addition to the fact that a series of stirring flows as shown in FIG. 2 is basically stably generated in the triple stirring region 5 formed by the respective stirring blades 4, By making a positive difference in the improved earth pressure in the stirring region 5 by controlling the rotational speed, it is possible to promote the horizontal flow as described above, thereby obtaining an excellent stirring and mixing effect. A ground improvement effect can be obtained. Moreover, since such a difference in improved earth pressure can be performed only by increasing or decreasing the rotational speed of the rotary shaft 1, there is almost no cause for cost increase without requiring any troublesome operations or complicated mechanisms. It is also possible to reduce the total supply of solidification material by improving the mixing efficiency.

  In addition, as a specific process of the present embodiment, either the state of FIG. 3A or the state of FIG. 3B may be selected and the penetration process and the drawing process may be performed in that state. For example, the state of (a) at the time of penetration and the state of (b) at the time of withdrawal (or vice versa), or the state of (a) and the state of (b) are alternated at regular intervals during the penetration process and the withdrawal process. It is also possible to repeat the above, and by doing so, the stirring and mixing state in the entire stirring region 5 can be made more uniform.

  In addition, when the state of (a) or (b) is continued for a certain period of time, the improved earth pressure at the center or both sides gradually increases depending on the geology, the supply amount of the solidified material, and other conditions. At some point in time, the rise limit may be reached and the earth pressure will flow out rapidly and the earth pressure will stabilize. In such a case, the pulsation of the improved soil will naturally occur in the stirring region 5, As a result, a sufficient stirring and mixing effect can be obtained even by pulsation.

  By the way, the solidifying material (cement slurry, cement powder, etc.) from the rotating shaft 1 may be supplied from each rotating shaft 1 evenly, and the discharge timing thereof is only at the time of penetration, only at the time of withdrawal, or at the time of penetration. Either may be used at the time of drawing, but in any case, it is also possible to adjust the supply amount of the solidifying material from the rotating shaft 1 in accordance with the setting of the rotational speed of the rotating shaft 1 as described above. Be That is, as shown in FIG. 3 (a), the supply amount of the solidified material from the central rotating shaft 1b with the increased rotational speed is relatively increased, and the rotating shafts 1a on both sides with the decreased rotational speed are also provided. As shown in (b), the supply amount of the solidified material from the rotating shafts 1a on both sides whose rotation speed is increased is relatively increased. At the same time, if the supply amount from the central rotary shaft 1b having a reduced rotation speed is relatively small (or supply is stopped), the difference in the improved earth pressure is caused by the difference in the supply amount of the solidified material as described above. Thus, the flow of the improved soil can be further promoted, and the supplied solidified material can be put on the flow of the improved soil as it is and can be smoothly distributed over the entire stirring area.

  Further, in the three-axis deep mixing processing method as in the present embodiment, there may be a case where a difference occurs in the load applied to the rotary shaft 1a on both sides and the central rotary shaft 1b depending on the ground conditions. For example, when the original ground is cohesive soil, the rotational resistance with respect to the rotating shaft 1a on both sides is larger than the rotating resistance with respect to the rotating shaft 1b on the both sides, and a larger load is applied to the rotating shaft 1a on both sides than the central rotating shaft 1b. On the contrary, when the original ground is sandy soil, a larger load may be applied to the central rotating shaft 1b than to the rotating shaft 1a on both sides. Therefore, it is conceivable to adjust the rotational speed as described above in accordance with the load applied to the rotary shaft 1.

  When such a load imbalance occurs, as shown in FIGS. 3A and 3B, the rotational speed of the rotary shaft 1 to which a high load is applied is relatively reduced to increase its torque. In addition, by relatively increasing the number of rotations of the low-load rotary shaft 1 and reducing its torque, the torque of each rotary shaft 1 can be appropriately adjusted according to the load, and the ground condition can be obtained. The optimum operation according to the operation becomes possible. In addition, at the same time, by providing a difference in the rotational speed, the above-described difference in the improved earth pressure and the flow of the improved earth due to the difference naturally occur, so that it is possible to obtain an excellent stirring and mixing efficiency.

  In the case of adjusting the rotational speed for the purpose of adjusting such a load, the increase / decrease in the supply amount of the solidified material as described above (increasing the supply amount from the rotating shaft with the increased rotational speed, It may not be preferable to reduce the amount of supply from the rotating shaft with a reduced rotational speed. In other words, increasing the supply amount of the solidified material can reduce the rotation resistance and expect the effect of reducing the load, but reducing the supply amount increases the rotation resistance and increases the load. Therefore, in order to reduce the load on a high-load rotating shaft, reducing the number of rotations (increasing torque), but reducing the amount of solidified material there may be counterproductive. Rather, it may be preferable to increase the supply amount. Therefore, the adjustment of the rotational speed and the adjustment of the supply amount should be set so that a preferable stirring and mixing state can be obtained in the entire stirring region in consideration of the ground conditions and other various conditions.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and specific steps and configurations of each part of the apparatus are considered in consideration of ground conditions and other conditions. Needless to say, various modifications and applications are possible without departing from the scope of the present invention. For example, in the above embodiment, the three rotation shafts 1 are driven independently by the respective drive sources 2, but the rotation directions of the rotation shaft 1a on both sides and the central rotation shaft 1b are reversed and their rotations are reversed. As long as the number can be controlled, it may be driven by the two drive sources 2 via an appropriate power transmission mechanism 3 as in the prior art.

It is a figure which shows the basic process of the triaxial deep-layer mixing processing method which is embodiment of this invention. It is a figure which shows the stirring state in a stirring area | region similarly. It is a figure which shows a specific process same as the above. It is a figure which shows the conventional triaxial deep-layer mixing processing method. 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 9,10 Discharge port

Claims (3)

Three rotating shafts equipped with stirring blades at the tip are arranged side by side, and while rotating these rotating shafts into the ground and reversely rotating and withdrawing from the ground, the solidified material is removed from the tip of the rotating shaft. A triaxial deep-mixing method for improving the ground by stirring and mixing in a triple stirring region formed by the stirring blades supplied to the ground,
A series of three types of rotating shafts, the rotating shafts on both sides are rotated in the same direction and the central rotating shaft is rotated in the opposite direction to the rotating shafts on both sides, whereby the improved soil continuously flows over the entire stirring region. A stirring flow of
In addition, by making a difference between the rotational speed of the rotary shafts on both sides and the rotational speed of the central rotary shaft, a difference is caused in the improved earth pressure between the both side portions and the central portion of the stirring region, thereby improving the soil between them. A triaxial deep mixing treatment method characterized by promoting the flow of water.   The triaxial deep mixing method according to claim 1, wherein the supply amount of the solidified material from the rotation shaft is set according to the rotation speed, and the supply amount from the rotation shaft having the higher rotation speed is set to the rotation with the lower rotation speed. A triaxial deep-mixing processing method characterized in that it is set to be larger than the supply amount from the shaft.   The three-axis deep mixing method according to claim 1, wherein the rotational speed of the rotary shaft is set according to the load, and the rotational speed of the high-load rotary shaft is set smaller than the rotational speed of the low-load rotary shaft. A triaxial deep layer mixing method characterized by that.

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