JPS5949377B2 - Ground improvement methods and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves inserting a rotating shaft equipped with stirring blades into soft ground so as to be able to penetrate and pull it out, and discharging a ground improvement agent into the ground from inside the rotating shaft. This invention relates to the provision of new construction methods and equipment for ground improvement by mixing and solidifying viscous sludge.

By forcibly stirring and mixing various ground improvers including chemical improvers such as quicklime and cement with viscous ± (sludge) in soft ground, and creating column-shaped solidified parts in the ground, it is possible to improve soft ground. Ground improvement methods have recently become well-established as new methods in the construction foundation industry, with many successful results, and it is also known that many proposals have been made for improvement methods and equipment.

These various methods and devices can be broadly classified in terms of the improving agents used, devices, machine mechanisms, and especially the means of discharging and supplying the improving agents. It is classified into two categories: (a) where the improver is used as is, and (b) where the improver is used in the form of a slurry such as cement milk or mortar.
From the viewpoint of the mechanism of the machine, especially the means for discharging and supplying the improving agent, an improving agent such as quicklime is stored in a pouring pipe that can be penetrated and withdrawn freely, and is discharged into the ground from the lower end of the pouring pipe using a screw feeder inside the pouring pipe. The so-called batch method...a. A method in which slurry-like improver is transported as a fluid through piping and supplied from the pouring pipe.
...b, a method in which a solid improver is pneumatically transported using pressurized air and discharged from the inside of a rotating shaft equipped with stirring blades... classified as C.

Various current construction methods and equipment are listed above, as well as a, b, and c.
These methods emphasize the unique effects of each method, but recently, the combination method of Low-B is overwhelmingly used, but recently the injection stirring method, which is a combination method of E-C, is also difficult to put into practical use. The company has overcome this problem and is getting back on track.

In any of these types, it is necessary to continuously supply the improver, and in the case of the row b combination type, a rotating shaft equipped with stirring blades (
The slurry improver can be made into a hollow shaft by using the stirring shaft itself as a hollow shaft, and the slurry improver can be flowed into the hollow part and discharged near the stirring blade, or a special supply pipe can be provided and the dedicated supply pipe can be opened near the stirring blade to form a slurry. New types that do not use conventional pouring pipes have also been developed, such as ones that discharge improving agents.

In any case, the goal of conventional new construction methods and equipment is to improve construction efficiency and quality after soil improvement, but in this case, based on past experience and construction results, improvement quality exceeding a certain value, and variation. In order to achieve this, it is necessary to satisfy a certain value or more for the number of stirrings per hour by the stirring blade, and to improve the construction efficiency, it is necessary to increase the underground penetration and extraction speed of the device. To achieve this, it is possible to increase the number of stirring blades on the rotating shaft (stirring shaft) by arranging them in multiple vertical and multi-tiered configurations, and as a result, to increase and maintain the number of stirrings per hour, which minimizes the power consumption. However, improvements such as increasing the rotational speed of a single stirring blade or increasing the number of blades inside the blade have little effect in relation to the power consumption, and current methods and devices of this type cannot be used. However, in most areas, stirring blades are multi-staged.

However, even with these multiple and multi-stage stirring blades, there are common drawbacks, such as the formation of an unimproved layer at the tip of the rotating shaft, and cases in which the improvement agent cannot be supplied at all when the rotating shaft penetrates the ground. The present invention examines the problems and shortcomings of these conventional soil improvement methods and equipment, and in order to satisfy the demands for improving construction efficiency and improving quality after improvement, the present invention provides a multi-stage agitation system with multiple upper and lower stages. In addition to using blades, the soil improvement agent can be discharged and supplied near the stirring blades at different vertical positions in both the reciprocating strokes of underground penetration and underground extraction of the rotating shaft that is the rotating base that supports the stirring blades. By doing so, it is possible to obtain outstanding improvement effects that could not be attempted with conventional methods, and when it is difficult to supply and stir the improvement agent at the time of penetration due to soil conditions etc. This method can be used to completely resolve only the unimproved layer at the tip by discharging the improving agent during the drawing process.

Therefore, its first feature is that the rotating shaft equipped with stirring blades installed in the radial direction is rotated while penetrating into the ground to be improved, and the improvement agent supplied near the stirring blades is mixed into the ground. This is a ground improvement method in which the improvement agent that is pumped through the rotating shaft is pumped into the rotating shaft at the attachment root of the upper and lower stirring blades of the stirring blades, which are arranged in multiple rows in multiple vertical stages other than the rotating shaft. From each nozzle provided on the opposite side of the rotation direction, when the rotating shaft penetrates underground, the lower stirring blade is used, and when the rotating shaft is pulled out of the ground, the upper stirring blade is supplied. 2 is characterized by a rotary shaft outer cylinder that can be raised and lowered and rotated freely and equipped with a plurality of stirring blades arranged in the radial direction and in multiple stages above and below; an inner cylinder of the rotating shaft which is provided so as to be able to change its position independently and which also serves as a supply path for the improving agent; and an inner cylinder of the rotating shaft which is provided on the opposite rotation direction side of the rotating shaft at the attachment base of the upper and lower stirring blades of the outer cylinder of the rotating shaft. The improver supply nozzle communicates with the supply nozzle on the lower stirring blade side when the rotary shaft penetrates underground, and communicates with the supply nozzle on the upper stirring blade side when withdrawn from the ground, through the positional change of the inner cylinder with respect to the outer cylinder. The improvement agent switching supply hole is provided so as to be able to communicate with the supply nozzle of the present invention.

The present invention will be described in detail below based on the illustrated embodiments.
．． 2 is a longitudinal sectional front view of the main part of the rotating shaft equipped with the stirring blade according to the present invention, and FIG. 2 shows an overall view of an embodiment of the improved device using the stirring blade rotating shaft shown in FIG. In FIG. 1, 30 is a stirring blade rotating shaft, and in one embodiment of the present invention, the rotating shaft 30 is connected to a rotating shaft outer cylinder 31 and the outer cylinder 31 as shown in the figure.
The outer cylinder 31 has a composite tube shaft configuration with a rotary shaft inner cylinder 34 concentrically installed inside the cylinder, and two to three blade-shaped stirring blades 5a5b5C protruding in the radial direction are provided at the lower end of the outer cylinder 31 in multiple stages above and below. In the illustrated example, the outer cylinder 31 is arranged in three stages, top, middle, and bottom.As will be understood in the device embodiment described later in FIG. 2, the upper part of the outer cylinder 31 is omitted; outer cylinder 3
An outer cylinder portion not provided with stirring blades is connected to the upper part of the stirring blade 1 through a flange 38 etc. to form a rotating shaft 30 of a required length, and rotational motion is transmitted to the stirring blades 5a to 5C.
The stirring torque will be applied to the

Although the upper part of the rotating shaft inner cylinder 34 is not shown, the outer cylinder 31
As shown in the example of the device shown in FIG. a working disc 37a which has a larger diameter than the outer cylinder 31 and is secured to the lower end of the outer cylinder 31 in an overhanging manner;
Switching valve plate 3 equipped with a pointed head 37b for penetration at the lower end of 7a
7 is fixedly installed, and is engaged with a straight groove-shaped guide notch 40 provided on the inner surface of the outer cylinder 31 on the lower end circumferential side of the inner cylinder 31 to prevent free rotation of the cylinder 34 in the plane direction and to prevent vertical rotation. By providing a key-shaped regulation guide 39 that serves as a stopper that also serves as a straight guide in the direction and a stopper for aligning the nozzle of the upper blade when moving downward, the rotation shaft inner cylinder 3
4 rotates along with the rotation of the rotating shaft outer cylinder 31, but the inner cylinder 34 is also provided so that its position can be varied independently in the vertical direction relative to the outer cylinder 31. .

In one embodiment of the present invention, in the stirring blade rotating shaft 30 including the rotating shaft outer cylinder 31 and the rotating shaft inner cylinder 34, in the present invention, in the multi-stage stirring blades 5a to 5c in the outer cylinder 31, the intermediate stirring blade 5b is At the mounting positions of the upper stirring blade 5a and the lower stirring blade 5c except for the upper stirring blade 5a and the lower stirring blade 5c, an improving agent that opens toward the side opposite to the rotational direction of the rotating shaft 30 at the mounting base of each stirring blade 5a5c on the circumferential side of the outer cylinder 31. injection nozzle 32
．． 33 will be established respectively.

Further, to the upper and lower injection nozzles 32 and 33, a switching supply hole 35 is provided on the circumferential side of the rotating shaft inner cylinder 34 for supplying the improving agent that is pumped through the inner cylinder 34 together with, for example, pressurized air. .36 is installed above and below.

That is, an upper switching supply hole 35 corresponding to the injection nozzle 32 of the upper stirring blade 5a and a lower switching supply hole 36 corresponding to the injection nozzle 33 of the lower stirring blade 5c are provided on the upper and lower peripheral sides of the inner cylinder 34, respectively. When the rotating shaft 30 penetrates or is pulled out of the soil to be improved, the inner cylinder is moved by the resistance of the ground cohesive soil acting on both the upper and lower surfaces of the operating disk 37a of the switching valve plate 37 at the lower end of the inner cylinder 34. 34 to outer cylinder 31
By sliding the switching supply holes 35 and 36 vertically independently of The improving agent in the inner cylinder 34 is sprayed and supplied from this position into the target ground in line with the injection nozzle 33 of 5c, and on the other hand, when the rotating shaft 30 is pulled upward from the target ground, the upper switching supply is applied. The through hole 35 coincides with the injection nozzle 32 of the upper stirring blade 5a, so that the improving agent is sprayed into the ground at this position.

FIG. 1 shows a state in which the rotating shaft 30 has penetrated into the target ground. When the rotating shaft penetrates, the reaction force of the ground cohesive soil acts on the lower surface of the acting disk 37a of the switching valve plate 37. 37
a is always pressed against the outer cylinder surface a side throughout the entire penetration stroke, and the lower switching supply hole 36 works with the injection nozzle 33 of the lower stirring blade 5C to forcefully feed the inside of the inner cylinder 34 with, for example, pressurized air. The improving agent is jetted out from the same nozzle 33,
This is stirred and mixed by the lower stirring blade 5C, and the stirring and mixing is repeated by the subsequent intermediate stirring blade 5b1 and the upper stirring blade 5a, and this allows the rotating shaft 30 to penetrate underground, which was not possible in the past. A discharge mixing operation of the improver in the process will be obtained.

At this time, the upper switching supply passage hole 35 is not in communication with the injection nozzle 32 of the upper stirring blade 5a as shown in the figure, so that intrusion of sludge and water can be prevented.

In this way, the rotating shaft 30 that has penetrated to a predetermined depth in the ground to be improved rises from the same point and is pulled out above the ground surface, but in this pulling process, the resistance of the cohesive soil in the ground to be improved is Since a downward reaction force acts on the upper surface, more precisely, on the upper surface of the cylindrical portion corresponding to the difference between the outer diameter of the outer cylinder 31 and the outer diameter of the action disk 37a, the action disk 37a
1 Therefore, the switching valve plate 37 is lowered to open the lower switching supply hole 3.
6 is out of communication with the injection nozzle 33 of the lower stirring blade 5C, and on the contrary, the upper switching supply hole 35 is connected to the upper stirring blade 5a.
The improving agent in the inner cylinder 34 is ejected into the ground from the nozzle 32, and is first mixed and stirred by the upper stirring blade 5a, followed by the intermediate stirring blade 5b and the lower part. This working state continues throughout the entire drawing stroke while repeated stirring and mixing is performed by the stirring blade 5c.

The clayey soil resistance acting on the cylindrical portion due to the difference in the outer diameter of the working disk 37a is, for example, when the outer diameter of the outer cylinder 31 is 200φ and the working disk 3 is
When the outer diameter of the inner tube 7a is 300φ, the adhesive force of the clay soil reaches about 100 when the clay is about 3 tons/row, so it is sufficiently possible for the inner cylinder 34 to move downward independently.

Further, the regulation guide 3 that engages with the guide notch 40 described above
9, each nozzle 32, 33 in this penetration and withdrawal process.
The nozzle and each through hole 35, 36 are aligned at a specified position, and the inner cylinder 34 freely rotates to prevent misalignment between the nozzle and the through hole in the plane direction.

That is, in the rotating shaft 30 of the present invention, when the switching valve plate 37 is used as in the embodiment, the relative positional change of the inner cylinder 34 to the outer cylinder 31 during the penetration and withdrawal strokes can be made independently and without any power. Although the switching is automatic, it is also possible to use some kind of power means for this vertical movement.

In the present invention, in the outer cylinder 31 of the upper and lower stirring blades 5a, 5c, that is, at the attachment root of the blade outside the rotation axis, the injection nozzle 32, 33 is directed toward the side opposite to the rotation direction of the rotation axis 300, that is, toward the rear in the rotation direction. Taking dry powder using air as an example, when ejecting the improver with pressurized air, the gap immediately after the stirring blade 5a5c rotates is improved along the back surface of the blade. Since the agent is injected, it is ensured that the improvement agent reaches the ground within the diameter range of the blades 5a, 5c with relatively low air pressure, and at this time, the improvement agent is injected into the ground within the diameter range of the blades 5a, 5c.
The pressurized air and the improver are separated from each other due to the change in flow velocity as they exit from the 33 to the soil, and the improver diffuses well into the gaps in the soil and solidifies with the cohesive soil through forced stirring. This is reliable, and the pressurized air that reaches the tip of the blade can be routed through air recovery passages and guides formed on the upper side of the blade as necessary, and even if this is not done, the pressurized air that has reached the tip of the blade can be routed through air recovery passages and guides formed on the upper side of the blade. It is possible to easily collect the outer cylinder 31 along the outer periphery due to the gap therebetween.

In addition, the ground improvement agent used in the present invention can be any powder, powdered cement, quicklime, removed gypsum, slag, or slurry such as cement milk or mortar. Of course there is.

In addition, as mentioned earlier, the switching supply passage 3 of the rotating shaft inner cylinder 34 for the upper and lower injection nozzles 32 and 33 of the rotating shaft outer cylinder 31
The drive means 5 and 36 for switching communication during underground penetration and extraction processes are equally effective even if they are not based on the use of viscous earth pressure or resistance as shown in the figure.

An example of a ground improvement device using the agitating blade rotating shaft 30 of the present invention is shown in FIG. 2.

The soil improvement device of Fig. 2 InIII is a double type with rotating shaft 30, and one that uses a powder or granular improving agent.
As an example, in Figure I■■, a slide frame 3 is installed on a frame 2 erected on a base 1 via an appropriate slide guide so that it can move up and down in a straight line, and two units are attached to the same frame 3. A stirring blade rotating shaft 30 (the number of which is free) is rotatably provided in a downwardly protruding manner, and stirring blades 5a to 5c are arranged in three stages in upper, middle and lower stages at the lower end of an outer cylinder 31 of the rotating shaft 30. As a mechanism for moving the frame 3 up and down in a straight line, in the illustrated example, an endless band 8 stretched between the upper and lower driven wheels 6, the driving wheels 7, and both wheels 6 and 7 of the frame 2 is provided, and a part of the endless band 8 is It is connected to the frame 3 via a connecting part 9, and the driving wheels 11 of the drive shaft 10 on the drive wheel T side are driven from the prime mover 12 provided on the base 1 through the driving wheels 13 and belt 14. The pedestal 3 is raised and lowered through circulation, thereby raising and lowering the rotating shaft 30.

The pedestal 3 is provided with a rotation motor 15 for the rotation shaft 30, and although not shown, the rotation is applied to the rotation shaft outer cylinder 31 via an appropriate transmission mechanism, whereby the outer cylinder 3
The rotating shaft 30 consisting of an inner cylinder 34 rotates and penetrates into the ground to be improved, reaches a required depth point, and is pulled out from this point, and the upper end of the inner cylinder 34 of the rotating shaft 30 is A blowing agent supply port 17 is provided.

A chemical improver such as cement, quicklime, removed gypsum, ore slag is applied to the base 1 along with pressurized air to the inner cylinder 3.
4 is provided.

That is, a hopper 19 connected to an air transport pipe 18 for pumping a powdered improver together with pressurized air, a screw conveyor 21 communicating with the hopper 19 via a rotary valve 20,
A distribution supply machine 22 is provided which communicates with the discharge port of the conveyor 21, and has two supply ports 23 and 23 which are dividedly supplied by a distribution valve in the distribution supply machine 22, and one of the two rotating shafts 30, 30. Blow supply port 17.17 to cylinders 34, 34
The powdered improver is forced into the hopper 19 from the air transport pipe 18 and is supplied to the screw conveyor 21 through the opening of the rotary valve 20. From the conveyor 21, through the supply ports 23, 23 of the distribution feeder 22, the feed pipes 24, 24, and into the inner cylinders 34, 34 of each rotating shaft 30, 30, the supply port 17 is blown.
．． 17 with pressurized air, and when the rotary shaft 30 penetrates underground, it is injected through the injection nozzle 33 on the lower stirring blade 5C side, and when it is pulled out of the ground, it is injected through the injection nozzle 32 on the upper stirring blade 5a side. 25 is a pack filter of the hopper 20, and 26 is a support of the frame 2.

According to this device, the rotary shaft 30 penetrates into the soil to be improved to a desired depth, and at the same time, while giving rotation to the rotary shaft 30, the lower switching supply hole 36 of the inner cylinder 34 is connected to the lower stirring blade 5C. The ink is ejected from the injection nozzle 33, and stirring and mixing is repeated in the order of the stirring blades 5c5b5a to advance the penetration stroke to a predetermined depth.After reaching the predetermined depth, the rotating shaft 30 is successively pulled upward, while As the rotation progresses, the upper switching supply hole 35 is ejected from the injection nozzle 32 of the upper stirring blade 5a, and stirring and mixing are repeated in the order of the stirring blades 5a5b5c, thereby advancing the drawing process to the ground surface. explains that it is a type that uses pressurized air and injects a solid improver into the ground while stirring, but this is just one example. It is also applicable to use pumping means.

The construction method and device of the present invention are superior to conventional construction methods and devices in the following points.

That is, in the present invention, the stirring blade rotating shaft 30 is capable of supplying the improving agent and stirring and mixing it even during the process of penetrating into the soil to be improved, and is capable of supplying the improving agent and stirring and mixing it during both the penetrating and withdrawing processes. Forced stirring and mixing naturally doubles the number of times of stirring in the stirring blade, which improves the quality of the improved soil, and makes it easier to obtain improved soil with a uniform, stable, and dense consolidated structure without any variation. This also significantly improves speed and efficiency.

At this time, when the rotating shaft 30 penetrates, the inner cylinder 34 can also be used as an air jet flow path, so that the penetration resistance is reduced and the penetration speed is increased.

In addition, according to the reciprocating mixing and stirring process of the present invention, problems such as the occurrence and remaining of unimproved areas on the tip side of the rotating shaft can be avoided.
Discharging and stirring the improver during both the penetration and withdrawal processes is the most effective method.Increasing the number of stirrings per hour of the multi-stage stirring blade improves the efficiency of construction. In addition to effectively satisfying the requirements of increasing penetration and withdrawal speeds with the minimum power consumption, continuous reciprocating supply of the improver reduces the amount of improver supplied per hour by half. In the case of single-pressure feeding in combination with pressurized air, the amount of air mixed into the soil will be reduced, and the air mixed into the soil will be recovered at this time, but the one-way discharge only during the drawing process and the present invention There is a considerable difference in the difficulty of reciprocating discharge during the penetration and withdrawal process, and the present invention reduces the amount of air mixed in. It also reduces the power of the compressor, etc., and is advantageous in terms of air recovery. .

Moreover, according to the adoption of the switching valve body 37 using earth pressure in the embodiment,
Switching the discharge of the improving agent during the penetration and withdrawal processes can be done without any power, but in the case of power-using types such as cylinders, the structure is complicated due to the need for swivel joints, slip rings, etc.
It has no drawbacks such as being prone to breakdowns or affecting smooth discharge, and has value as a unique and innovative new technology as a new ground improvement method, compared to conventional and current improvement methods. It is excellent.

1 Brief Description of the Drawings FIG. 1 is a vertical sectional front view of the main part of the stirring blade rotating shaft as an embodiment of the construction method of the present invention, FIG. 1 is a sectional view taken along the line A-A in FIG. 1, and FIG. IIIm is a plan view, a front view, and a side view of an embodiment of the device of the present invention.

) 30... Stirring blade rotating shaft, 31... Rotating shaft outer cylinder, 32.33... Improver injection nozzle,
34... Rotating shaft inner cylinder, 35, 36...
Switching supply hole, 37...Switching valve plate, 5at5b
t5c,... Stirring blade.

Claims (1)

[Scope of Claims] 1. A ground improvement method in which a rotating shaft equipped with stirring blades provided in a radial direction rotates while penetrating into the ground to be improved, and an improvement agent supplied near the stirring blades is mixed into the ground. There it is,
The improving agent to be pumped through the rotating shaft is transferred to a stirring blade provided outside the rotating shaft in a plurality of rows of vertically arranged stirring blades in multiple stages. A soil improvement method characterized by switching supply from each nozzle from the lower stirring blade when the rotating shaft penetrates underground, and from the upper stirring blade when pulling the rotating shaft out of the ground. 2. A rotary shaft outer cylinder that can be raised and lowered and rotated freely and equipped with a plurality of stirring blades arranged in the radial direction and in multiple stages above and below, and a rotary shaft outer cylinder that is inserted into the outer cylinder so that it can accompany the outer cylinder and whose position can be changed independently with respect to the outer cylinder. a rotary shaft inner cylinder that can be provided and also serves as a supply path for the improving agent; a improving agent supply nozzle that is provided on the opposite rotational direction side of the rotating shaft at the attachment root of the upper and lower stirring blades of the rotary shaft outer cylinder; By changing the position of the inner cylinder of the rotating shaft with respect to the outer cylinder, it is possible to communicate with the supply nozzle on the lower stirring blade side when the rotating shaft penetrates underground, and to communicate with the supply nozzle on the upper stirring blade side when withdrawing from the ground. A soil improvement device comprising: a changeover supply hole for an improvement agent provided in the soil improvement device;