JPH0223631Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a deep mixing treatment device that improves the ground by discharging and stirring cement slurry into the soft earth and sand of the improved ground.

(Prior Art) This type of deep mixing processing apparatus has conventionally generally been configured as shown in FIGS. 3 and 4. Here, FIG. 3 is a partially omitted longitudinal sectional view, and FIG. 4 is a bottom view. In both of these drawings, reference numeral 2 denotes the deep mixing treatment apparatus, which includes a main body steel pipe 3, a stirring shaft 4, a connecting casing 5, a speed reducer 6, and the like. The main steel pipe 3 is fixed to the connection casing 5 so as to hang down thereon, and its tip end is formed into a conical shape. Four stirring shafts 4 are arranged around the main steel pipe 3 in parallel thereto. Each of the stirring shafts 4 is rotatably supported by a bearing 7 attached to the main steel tube 3, and the tip of the stirring shaft 4 is also formed into a conical shape like the tip of the main steel tube 3. ing. A slurry discharge port 8 is provided near the tip of the stirring shaft 4.
A plurality of stirring blades 9 are attached to the periphery of the stirring blade 9 . This stirring shaft 4 is rotationally driven via the speed reducer 6.

Seabed surface 10 to be improved on the deep mixing treatment device 2 suspended in the conventional work boat configured as described above.
lower to. When the tip of the stirring shaft 4 reaches the seabed surface 10, it penetrates into the earth and sand 11 on the seabed while rotating the stirring shaft 4. At the same time, cement slurry is discharged from the slurry discharge port 8, and the cement slurry is stirred and mixed into the earth and sand 11 on the seabed by the rotation of the stirring blades 9. The deep mixing device 2 is pulled up after the stirring shaft 4 penetrates to a predetermined depth while mixing the cement slurry into the earth and sand 11 in this manner. As a result, the cement slurry is mixed into the earth and sand 11 on the seabed, which solidifies over time and improves the ground. At this time, the main steel pipe 3 rotatably supports the stirring shaft 4 via the bearing 7, and functions to suppress displacement of the stirring shaft 4 in the horizontal direction when penetrating into the earth and sand 11 on the seabed. .

(Problems to be solved by the invention) In such a conventional deep mixing treatment device 2, when mixing cement slurry into the seabed sediment 11, each stirring shaft 4 and main body steel pipe 3 penetrate into the seabed sediment 11. will be done. Therefore, these stirring shafts 4
The amount of unimproved soil 12 removed by the main steel pipe 3 is extremely large as shown in Fig.
Since a large amount of soil mixed with cement slurry is also removed, unimproved soil 12 without cement slurry mixed in may be mixed into the planned finished shape area after the deep mixing treatment device 2 is pulled up. However, it had the disadvantage that it could not be improved sufficiently.

The present invention was developed with attention to this point, and by minimizing the amount of soil removed during penetration, it is possible to prevent unimproved soil from entering the planned finished area after lifting the deep mixing treatment equipment. The purpose is to provide a deep mixing treatment device that can reliably improve the ground.

(Means for solving the problem) In order to solve this problem, in the present invention, a plurality of stirring shafts each having a slurry discharge port and a plurality of stirring blades near the tip are provided in the connection casing, and the stirring shafts are connected via bearings. Attach a main body steel pipe that rotatably supports the stirring shaft, drive the stirring shaft to rotate through a speed reducer and penetrate into the improved ground, and mix the cement slurry discharged from the slurry discharge port into the earth and sand of the improved ground. The deep mixing treatment device for soil improvement is constructed by opening the top and bottom of the main steel pipe and slidably mounting a piston having a predetermined weight inside the main steel pipe.

Further, the deep mixing treatment device may be constructed by engaging the piston between upper and lower piston rubbers using a universal joint.

(Function) With this configuration, most of the improved soil mixed with cement slurry that is removed into the main steel pipe is guided into the main steel pipe, so it is not removed to the outside. When the deep mixing treatment equipment is pulled up after penetrating and discharging to the target depth, the improved soil introduced into the main steel pipe by the piston action is re-stirred while being reliably returned, allowing the deep mixing treatment equipment to be lifted up. There is no possibility that unimproved soil will later get mixed into the planned finished shape area, making it possible to reliably improve the ground.

Furthermore, if the main steel pipe is bent due to external force when penetrating into the seabed, the structure of the piston is such that the upper and lower piston rubbers are engaged by a universal joint, so the main steel pipe will not bend to some extent. However, the piston can be slid smoothly.

(Example) Next, an example of implementation of the deep mixing processing apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a partially omitted vertical sectional view of an embodiment of the present invention, and FIG. 2 is a bottom view thereof. In both of these figures, 1 is the deep mixing processing device according to the present invention,
13 is a main body steel pipe, and 14 is a piston having a predetermined weight. This main body steel pipe 13 has an inner diameter of 80 cm, for example.
The front and rear hollow pipes are open at the top and bottom. Moreover, the piston 14 is connected to this main body steel pipe 13.
It has a diameter equal to the inner diameter of the main body steel pipe 13, and is slidably mounted inside the main steel pipe 13. 15 is this piston 1
4, which is connected to a winch for lifting and lowering the piston (not shown),
The piston 14 is structured to be able to move up and down as desired. The other parts are the same as the corresponding parts of the conventional deep mixing processing apparatus 2 shown in FIGS. 3 and 4, and are given the same reference numerals.

The operation of the deep mixing processing device 1 configured as described above will be explained next.

First, the deep mixing device 1 is lowered to the seabed surface 10 with the lower surface of the piston 14 positioned at the lower end of the main steel pipe 13. During this time, a winch for raising and lowering the piston is unwound in synchronization with the lowering speed of the deep mixing treatment apparatus 1, and the positional relationship between the lower surface of the piston 14 and the lower end of the main steel pipe 13 is maintained.
When the tip of the stirring shaft 4 reaches the seabed surface 10, the stirring shaft 4 is driven and rotated via a speed reducer and penetrates into the earth and sand 11 on the seabed. At the same time, cement slurry is discharged from the slurry discharge port 8, and the cement slurry discharged by the rotation of the stirring blades 9 accompanying the rotation of the stirring shaft 4 and the sediment 1 on the seabed.
1 and mix by stirring.

At the start of this discharge mixing, the winch for raising and lowering the piston is turned off, only the deep mixing processing device 1 is lowered, and the piston 14 is stopped at that position.
Therefore, as the deep mixing treatment device 1 descends, improved soil mixed with cement slurry as described above is introduced into the main steel pipe 1. Thereafter, the deep mixing device 1 continues stirring and mixing the cement slurry and the earth and sand 11 to a predetermined depth. As mentioned above, since the deep mixing device 1 descends while stirring and mixing the cement slurry with the earth and sand 11, the improved earth and sand can be introduced into the main steel pipe 13 relatively smoothly due to the lubricating effect of the cement paste. be done.

After mixing the cement slurry to a predetermined depth, the deep mixing device 1 is pulled up.
During this time, the stirring shaft 4 continues to rotate. Also, the winch for raising and lowering the piston remains in the off position. Therefore, pressure due to the weight of the piston 14 is applied to the improved soil introduced into the main steel pipe 13 as the deep mixing treatment device 1 is raised. The improved soil pushed out of the main steel pipe 13 by this pressure is re-stirred by the rotating stirring blades and becomes integrated with the surrounding improved soil. This improved earth and sand can also be discharged relatively smoothly due to the lubricating action of the cement paste mentioned above. Also, if a slow hardening cement paste is used, adaptability to elapsed time will be increased.

Although the present invention has been described above in detail according to the illustrated embodiments, the present invention is not limited thereto.
It includes various variations.

For example, if the weight of the piston 14 alone is insufficient to push out the improved soil introduced into the main steel pipe 13, a structure that allows seawater to be introduced to an appropriate height from the top surface of the piston may be used to push out the improved soil using the weight of the seawater. It can also be used for. In this case, a cleaning action by the seawater inside the main steel pipe 13 can also be expected.

Furthermore, as a measure to prevent the wire rope 15 from being cut in the event that excessive resistance occurs between the main body steel pipe 13 and the piston 14 when the deep mixing treatment device 1 is lowered, a buffer 16 shown in FIG. 5 is installed on the piston. It may be provided between the winch for lifting and lowering and the piston 14. In the figure, reference numeral 17 is a guide rail that is installed vertically and has a stopper 18 at its lower end.
Reference numeral 19 denotes a weight arranged so as to be able to slide vertically between the guide rails 17 by wheels 20, and the wire rope 15 passes through a pair of through holes and is hung on a pulley 21 provided on the lower surface. It is being
The weight of this weight 19 is set to a value that is the sum of the weight of the piston 14 (and its weight if seawater is introduced), the frictional force between the piston 14 and the inner wall surface of the main steel pipe 13, and an appropriate allowance weight. be done. Moreover, 22 is a load cell arranged between the pulley 21 and the lower surface of the weight 19.

In the buffer mechanism 16 configured in this way, when an excessive force is applied between the main steel pipe 13 and the piston 14 and the tension of the wire rope increases, the load cell 22 detects that the tension exceeds a predetermined value. Then, this detection signal is sent to an operation room or the like to generate an alarm such as overload cutoff. At this time, even if there is some delay in this overload cutoff, etc., the weight 19
Since the wire rope rises along the guide rail 17, excessive force is not applied to the wire rope, and breakage of the wire rope can be prevented. Note that if the load cell 21 is also provided with a function of detecting a lower limit value, it is also possible to detect slack in the wire rope 15 and issue an alarm.

In addition, since the piston 14 is tightly fitted into the main steel pipe 13, if the main steel pipe 13 is bent due to external force when penetrating into the seabed, etc.
It is also conceivable that it will not be able to slide. As a countermeasure for this, the piston 14 is constructed as shown in FIG. That is, the upper and lower piston rubbers 23 are connected by a universal joint 24, and each piston rubber 23 can freely rotate without being restrained by the other, so that the main body steel pipe 13 A piston 14 that can smoothly slide even when subjected to some bending deformation is obtained. The shape of the piston rubber 23 is similar to that of the main body steel pipe 13.
Care is taken to prevent the lip portion from getting caught in the joint portion 25. Furthermore, in order to reduce the frictional force between the piston rubber 23 and the inner surface of the main steel pipe 13 and to obtain smooth sliding of the piston 14, forced lubrication with grease or the like may be performed.

(Effects of the invention) The present invention is constructed as described above, and in the process of penetrating the stirring shaft into the sediment on the seabed, there is a structure inside the main steel pipe to regulate the horizontal displacement of the stirring shaft. In the process of introducing improved soil mixed with cement slurry and pulling out the stirring shaft in reverse, the improved soil inside the main steel pipe is gradually removed by the action of the piston that is slidably placed inside the main steel pipe. Since the soil is being discharged, improved soil is hardly removed by the main steel pipe, but if this deep mixing treatment equipment is used, unimproved soil will not mix into the planned finished shape after being pulled up and reduce its quality. This makes it possible to easily carry out reliable ground improvement.

In addition, the piston is made to slide freely by engaging the upper and lower piston rubbers in the main body steel pipe with a universal joint, so even if the main body steel pipe is slightly bent, the piston can slide smoothly. be able to. Since the cement slurry is discharged from the tips of the plurality of stirring shafts of the connection casing through the slurry discharge ports and is stirred by the stirring blades in the vicinity, mixing with the earth and sand on the seabed is performed efficiently.

Furthermore, since the deep mixing treatment device according to the present invention is constructed by supporting a plurality of stirring shafts around the main body steel pipe, it is possible to improve a wide range of ground with a single ground improvement operation.

[Brief explanation of the drawing]

FIG. 1 is a partially omitted vertical sectional view showing an embodiment of the deep mixing device according to the present invention, FIG. 2 is a bottom view thereof, and FIGS. 3 and 4 are examples of the conventional deep mixing device. FIG. 5 is a configuration diagram showing an example of a buffer mechanism used in the present invention, and FIG. 6 is a front view showing an example of a piston. 1, 2... Deep mixing processing device, 3, 13... Main body steel pipe, 4... Stirring shaft, 5... Connection casing,
6... Reduction gear, 7... Bearing, 8... Slurry discharge port, 9... Stirring blade, 14... Piston, 15...
wire rope.

Claims (1)

[Claims for Utility Model Registration] (1) A connection casing includes a plurality of stirring shafts each having a slurry discharge port and a plurality of stirring blades near their tips, and the stirring shafts are rotatably supported via bearings. The main body steel pipe is attached, and the stirring shaft is driven to rotate through a speed reducer while penetrating into the improved ground, and the cement slurry discharged from the slurry discharge port is mixed into the earth and sand of the improved ground to perform deep ground improvement. The mixing treatment device is characterized in that the main steel pipe has openings at the top and bottom, and a piston of a predetermined weight is slidably mounted therein, so that dirt can enter and be discharged from the main steel pipe. deep mixing processing equipment. (2) The deep mixing treatment apparatus according to claim 1, wherein the piston is characterized in that upper and lower piston rubbers are engaged by a universal joint.