JPH07197445A - Deep mixing method of soil stabilization - Google Patents

Abstract

PURPOSE:To widen the degree of freedom in design and facilitate setting of the optimum improvement ratio, by optionally altering the sectional shape of an improving pile in accordance with the ground depth. CONSTITUTION:A pair of right and left excavation blades 7 are provided as a unit at the underside of the rotary shaft 1 of an agitator and a pair of agitation blade 2 and auxiliary blade 3 are attached at the underside of the excavation blades 7 so as to be freely protruded or retracted and further, a fluid pipe is set to deliver and inject an improving agent to the rotary shaft 1. The rotary shaft 1 is rotated to excavate a hole 36 having the same diameter with the excavation blades 7 to a specified depth in the objective soil of ground 10 and the bottom is widened by the agitation blade 2 and at the same time, an improving agent is discharged through the fluid pipe of the rotary shaft 1 to mix with the soil and agitate it. Subsequently, when pulling out the rotary shaft 1 while discharging the agent, the agitation blade 2 and the auxiliary blade 3 are retracted to coincide with the excavation blade 7 diameter but the agent is continuously discharged. In this way, the ground is excavated by the agitation blade 2 while being conically constricted so as to lessen the inner diameter as it goes up to the ground 10 surface and the widened bottom of the improving pile 11 can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is to agitate the soil to be improved and the agitating agent by rotating the agitating blade while discharging and injecting mortar, cement milk, powdery and granular improving agent (solidifying agent) in the ground. The present invention relates to a deep-layer mixing processing method for mixing to form an improved processing pile.

[0002]

2. Description of the Related Art This type of deep-layer mixing processing method is usually composed mainly of a rotary shaft rotated by a drive motor and a stirring blade fixed to the lower peripheral portion of the rotary shaft so as to be integrally rotatable. Is carried out by using a stirring and mixing treatment apparatus provided with a supply passage for feeding in along the rotation axis. And
The improvement agent is conveyed through the supply passage to the discharge port provided at the root of the stirring blade, discharged while rotating the stirring blade, and mixed and stirred with the surrounding soil to be improved to form the improved treatment pile. is there.

[0003]

In the above conventional processing method, the stirring blade is simply rotated together with the rotating shaft,
Since the rotation locus drawn by the stirring blades during stirring is represented by a simple circle when viewed in plan from the upper side, the improved treated pile shape obtained is also substantially cylindrical. However, depending on the ground area or the purpose of improvement, it may be preferable to change the shape of the improved pile according to the depth by enlarging the bottom of the cylinder or enlarging an arbitrary depth. This is because, for example, there are construction areas in which the soil quality and the like greatly differ depending on the depth of the ground, and when a vertical support force, a K value, and the like are satisfied, a simple column increases the cost of construction.

Although it is conceivable to form an improved treated pile in which the bottom portion is expanded by using a bottom expanding bucket in the conventional method, when the bottom expanding bucket is used, the construction conditions are restricted and the depth is arbitrary. Since the diameter of the part cannot be expanded, the applicable range is extremely limited.

The object of the present invention is to solve the above problems and to arbitrarily change the cross-sectional shape of the improved treated piles according to the depth of the ground, thereby expanding the degree of freedom in design and improving the soil quality of the construction area. It is an object of the present invention to provide a deep-layer mixing processing method in which the matched optimum improvement rate can be easily achieved and the economical efficiency and reliability can be improved.

[0006]

In order to achieve the above object, the present invention is to excavate under the ground while rotating a stirring blade fixed integrally rotatably to a lower peripheral portion of a rotary shaft, and Inject the improver into the excavated soil to be improved,
In the deep-layer mixing processing method of mixing and stirring the soil to be improved and the improving agent to form an improved processing pile of a predetermined length, the stirring blade is provided so as to be able to advance and retreat from its projecting end surface, and the projecting amount thereof is controlled. The auxiliary blade is arbitrarily adjusted by means, and the amount of protrusion of the auxiliary blade is changed through the control means in the course of the ground depth forming the improved treatment pile so that the cross-sectional shape is in the longitudinal direction. The main part is to form different improved piles in each part.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. The deep-layer mixing processing method according to the present invention forms improved processing piles having different cross-sectional shapes at each portion in the longitudinal direction, and the stirring-mixing processing device illustrated in FIG. 5 is used for construction. Therefore, first, a device configuration used in the method of the present invention will be described.

In the apparatus shown in FIG. 5, the excavation blade 7 composed of a pair of left and right blade portions extending substantially perpendicularly outward from the lower periphery is fixed to the rotary shaft 1 rotated by the drive motor so as to be integrally rotatable. At the same time, the stirring blade 2 composed of a pair of left and right blade portions extending at a substantially right angle outwardly from the peripheral surface is integrally rotatably fixed to the periphery located above the excavation blade 7. In addition, as in the conventional case, the mortar, the cement milk, the powdery and granular improving agent (solidifying agent), which is injected into the soil to be improved in the same manner as in the conventional case, is passed through the rotating shaft 1 and is discharged and injected. A fluid pipe is installed.

Each of the stirring blades 2 is formed in a hollow cylindrical shape, one end of which is opened in the rotary shaft 1 and the other end of which is opened to the outside. Inside each stirring blade 2, an auxiliary blade 3 and a hydraulic cylinder 4 are arranged.
The auxiliary blade 3 is arranged so as to be able to move forward and backward from the other end of the stirring blade 2, and has a piston 4 of a hydraulic cylinder 4 which is a driving means.
It is fixedly attached to a. Then, the hydraulic cylinder 4 is driven to control the advance / retreat in the direction of arrows B-C in the figure. Each hydraulic cylinder 4 is fixedly attached inside the stirring blade 2, and further connected to a hydraulic controller 6 via a hydraulic pipe 5. The hydraulic controller 6 drives the hydraulic cylinder 4 based on the data input to the central processing unit (CPU) 8 based on a command from the central processing unit 8 to adjust the protrusion amount of the piston 4a. By this adjustment, the amount of protrusion of the auxiliary blade 3 with respect to the stirring blade 2 can be adjusted. Further, data relating to the current depth position of the stirring blade 2 measured by a depth gauge (not shown) is also input to the central processing unit 8 so that the protrusion amount of the auxiliary blade 3 is adjusted according to the depth. It has become so.

Next, a control example of the hydraulic controller 6 in this embodiment will be outlined. In this example, firstly, as setting conditions,
Select the applicable shape and select the piston 4 in the hydraulic cylinder 4.
The shape function for the elongation amount of a is determined. However, the applied shape is not limited. Second, shape function (analog value)
Is A / D converted. Thirdly, the digital signal (ON / OFF signal) of the shape function is converted into the ON / OFF signal of the servo valve. Fourth, the resolution of the servo valve for counting control is set to the resolution of the required cylinder stroke.
The resolution of this cylinder stroke is the minimum oil flow rate unit ΔQ that defines the amount of movement of the piston 4a at one time.
Fifthly, a counting control servo valve is incorporated in the cylinder circuit. Here, in the shape function, for example, when the pile shape has a square cross section, the radius of the inscribed circle is r, and the maximum expansion amount L of the auxiliary blade 3 by the hydraulic cylinder 4 is L. The maximum elongation L is a function of the rotation angle ωt of the stirring blade 2 and is represented by the following equation.

L = f (ωt) = r × tan ωt−r = r (tan ωt−1) Further, since tan π / 4 = √2, the range of the extension amount of the cylinder is as follows. 0 ≤ 1 ≤ 0.414 xr

In the calculation, first, the rotation angle ωt of the stirring blade 2 is A / D converted according to a predetermined resolution. Wherein in the case of shape example, obtains the L = r (tan ωt-1 ) corresponding to the minimum bit △ .omega.t ₁ of the rotational angle .omega.t for △ L _1.
Here, ΔL _n is counted as n times the minimum oil flow rate unit ΔQ. That is, ΔL _k = n × ΔQ ₁ and ΔL ₂ , ΔL ₃ , ΔL ₄ ... In accordance with the rotation of the stirring blade 2.
The ΔL _n signal is sent to the servo valve for counting control. From this servo valve, n × ΔQ corresponding to the signal of the calculation result
Oil flow into the cylinder circuit. A cylinder stroke is obtained according to the change of the shape function, and the piston 4
The shape of the pile is finished according to the amount of protrusion of a.

Therefore, the basic operation of the stirring and mixing processing apparatus is as follows. First, the rotary shaft 1 is rotated by a drive motor (not shown), and the excavating blade 7 and the stirring blade 2 are integrated with the rotary shaft 1.
Also rotates. Further, when the rotating rotary shaft 1 is lowered, the ground 10 is excavated by the rotation of the excavation blade 7, and further while the soil to be improved is cut after the excavation blade 2 is rotated by the rotation of the stirring blade 2. Is excavated to the deepest position that requires.
During this descent, the auxiliary blade 3 is most retracted from the stirring blade 2, that is, the state shown by the solid line in the figure. Next, the rotary shaft 1 is raised while the improving agent is being discharged. At this time, if it is necessary to stir the inside of the rectangular area of the plane, the piston 4a is gradually projected, and the piston 4a is gradually retracted as the piston 4a advances, so that the hydraulic cylinder 4 is controlled by the hydraulic controller. Control via 6. Then, the auxiliary blade 3 is also projected from the stirring blade 2 in conjunction with the advance / retreat of the piston 4a. Of course, in this control, the current depth data of the stirring blade 2 measured by the depth gauge described above is also taken into consideration, and the protrusion amount of the auxiliary blade 3 is adjusted according to the depth.

Next, FIG. 1 schematically shows construction steps for explaining an example of a deep layer mixing treatment method according to the present invention. Therefore, the procedure for performing the deep layer mixing process according to the present invention using the agitation mixing process device will be described in detail in the order of (a) to (e) of FIG. Note that, here, an example is given in which bottom expansion processing is performed with the bottom expanded. First, the rotary shaft 1 is positioned at a predetermined position on the ground 10, and then the rotary shaft 1 is rotated by a drive motor (not shown). Then, the excavating blade 7 and the stirring blade 2 also rotate integrally with the rotary shaft 1 [see FIG.
The auxiliary blade 3 here is in the most retracted state with respect to the stirring blade 2.

Then, the rotating rotary shaft 1 is lowered. Then, the soil to be improved 1 of the ground 10 is rotated by rotating the excavation wing 7.
0a is excavated, the excavation blade 7 and the agitation blade 2 are cut while the excavation target soil 10a is cut by the rotation of the agitation blade 2.
Enter with the rotary shaft 1 and are dug with substantially the same inner diameter [see (b) of the same figure].

After digging to the design depth, the hydraulic cylinder 4 is passed through the hydraulic controller 6 while the rotary shaft 1 is rotating.
Is controlled so that the piston 4a is gradually projected while discharging the improving agent. Then, the bottom portion is being excavated by the agitating blade 2 and expanded to a large diameter, and at the same time, the soil to be improved 10 that has been excavated.
a is stirred with the improving agent [see (c) of the same figure]. The current depth of the stirring blade 2 is measured every moment by the above-mentioned depth gauge, and the time when the auxiliary blade 3 projects is also managed as described above.

Next, the rotating shaft 1 is gradually pulled out while continuing to rotate the rotating shaft 1 and discharge the improving agent. At this time, the hydraulic cylinder 4 is controlled via the hydraulic controller 6,
The piston 4a is gradually retracted. Then, while advancing to the surface of the ground 10, it is excavated by the stirring blade 2 while being squeezed into a conical shape whose inner diameter decreases [see (d) of the same figure].

Even when the piston 4a is retracted to the final position, the rotation of the rotary shaft 1 and the discharge of the improving agent are continuously performed until the excavation blade 7 is completely pulled out from the ground 10 [(FIG. )reference]. Then, the so-called bottom-enhancement-type improved treatment pile 11 having a small cross-sectional area on the ground surface side and a wide bottom is formed. 2 shows the improved treatment pile 11 as shown in FIG.
It is the figure seen from the FF line direction of (e). The following effects can be obtained by the ground improvement treatment which has thus been subjected to the bottom expansion treatment. First, since the pile tip or the bottom end area can be increased, the tip support force can be increased, and if the tip support force is the same, the pile diameter part can be made thinner than the one that has not been subjected to bottom expansion treatment, The amount of excavated soil and the improving agent can be reduced, and the economical efficiency can be improved. Also,
Since the bearing capacity per pile is increased and the number of piles of the structure can be reduced, the construction period can be shortened and the construction cost can be easily reduced.

The shape of the improved treatment pile 11 is based on the data input to the central processing unit 8 (including the data on the current depth of the stirring blade 2), and the amount of protrusion of the auxiliary blade 3 is determined by the stirring blade 2. It can be arbitrarily formed by adjusting it according to the depth of the horizontal section. Even when the bottom side is enlarged, the horizontal section is not circular, but is rectangular as illustrated in FIG. 3 and FIG. It is also possible to change the cross-sectional area stepwise in the lengthwise direction like the shape. Also, the timing of discharging the improving agent is arbitrarily determined by the construction conditions,
Discharging can be performed even while the rotating shaft 1 is descending.

[0020]

As described above, in the deep-layer mixing processing method according to the present invention, during the rotation of the stirring blade together with the rotating shaft, the protrusion and retreat of the auxiliary blade are controlled by the control means. If this is done, it is possible to make the rotation trajectory drawn by the stirring blade into a non-circular shape, such as a substantially rectangular shape in a plane, depending on the timing of advancing and retreating of this auxiliary blade, and in addition, there is a partial difference depending on the ground depth. It becomes possible to form a shape-improved treated pile. Therefore, according to the method of the present invention, by freely changing the cross-sectional shape of the improved treated pile according to the depth of the ground, the degree of freedom in design can be expanded and the optimum improvement rate can be easily achieved, and the economy and reliability can be improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an example of a process to which a deep layer mixing processing method of the present invention is applied.

FIG. 2 is a view as seen from the direction of the line FF in FIG.

FIG. 3 is a plan view showing another improved example of the deep layer mixing processing method.

FIG. 4 is a cross-sectional view of the improved treated pile of FIG. 3 along the length direction.

FIG. 5 is a partially cutaway view showing an example of a stirring and mixing treatment apparatus used in the deep layer mixing treatment method.

[Explanation of symbols]

 1 Rotation axis 2 Stirring blade 3 Auxiliary blade 4 Hydraulic cylinder 6 Hydraulic controller 10a Soil to be improved 11 Improved pile

Claims (1)

[Claims] 1. An excavating process is performed under the ground while rotating an agitating blade integrally rotatably fixed to a lower peripheral portion of a rotating shaft, and an improving agent is injected into the excavated soil to be improved, In the deep layer mixing processing method of mixing and stirring the soil to be improved and the improving agent to form an improved processing pile having a predetermined length, the stirring blade is provided so as to be able to advance and retreat from its projecting end surface, and the projecting amount thereof is controlled. It has an auxiliary blade that is arbitrarily adjusted by means, and by varying the amount of protrusion of the auxiliary blade through the control means in the process of forming the improved treatment pile, the cross-sectional shape at each part in the longitudinal direction is changed. Deep mixing treatment method characterized by forming different improved treatment piles.