JP3527574B2 - Ground improvement method and ground improvement equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground suitable for use in improving soft ground to form a block, wall, grid, pile, layer, etc. solidified body or improved ground. The present invention relates to an improved construction method and a ground improvement device.

[0002]

2. Description of the Related Art As is well known, solidifying materials such as lime and cement are prepared in the form of slurry, and the slurry is stirred and mixed with the soil in the ground to hydrate the solidifying material slurry. Ion exchange between hydration products of clay reaction and clay minerals, or chemical consolidation reaction mainly consisting of pozzolanic reaction etc. is used to chemically solidify the soil and create improved piles in the ground. Therefore, there is a ground improvement method for improving the ground or forming a solidified body.

Conventionally, in this ground improvement method, a ground improvement device 1 based on a pile driver as shown in FIG. 6 has been used. In the ground improvement device 1, a rod 4 is rotatably supported by a support column 3 provided on a main body 2 around its axis, and a stirring blade 5 for stirring soil in the ground G is provided at a lower end portion of the rod 4. And an earth auger 6 for scraping the soil in the ground G, and a discharge port 7 for supplying the solidifying material slurry into the ground G from a solidifying material supply means (not shown). .

In order to improve the ground G by using the ground improving apparatus 1 as described above, first, the rod 4 is inserted into the ground G while rotating, and the ground auger 6 scratches the ground G to a predetermined depth. move on. At this time, the solidifying material slurry is ejected from the discharge port 7 at the lower end of the rod 4 by the solidifying material supply means. While pulling up the rod 4, the solidified material slurry ejected and the soil of the ground G are ground auger 6
And by stirring with the stirring blade 5 to form an improved pile in which the soil is solidified into a cylindrical shape in the ground G,
Ground G was being improved.

However, such a ground improvement device 1
Then, if the amount of the solidifying material slurry that is input to create the improved piles exceeds the gap between the soil of the ground G, the volume of the ground G expands and the earth pressure rises, and the ground G is displaced laterally. This may cause problems such as affecting existing existing underground structures and causing swelling of the ground surface.

At a site where such a problem may occur, a ground improvement apparatus 1'as shown in FIG. 5 is used. The ground improvement device 1 ′ has a spiral screw blade 9 over the entire length of the outer peripheral surface of the screw rod 8.
Is formed. In the ground improvement device 1 ′, the screw blades 9 that rotate integrally with the screw rod 8 discharge the surplus earth and sand to the ground, thereby preventing an increase in earth pressure in the ground G due to the supply of the solidifying material slurry. Has become.

[0007]

However, in the conventional ground improvement method and ground improvement device as described above,
There are the following problems. First, ground improvement device 1 '
In, the stirring blade 5 and the screw blade 9 rotate integrally. Therefore, if the lifting speed and the rotation speed of the stirring blade 5 are set to be constant so that the required improved quality of the ground G can be obtained, the screw blade 9 that is lifted and rotated at the same speed as the stirring blade 5 has a geological condition. When it changes, it is not possible to discharge the amount of earth and sand corresponding to the supply amount of the solidifying material slurry, which may cause a decrease in earth pressure due to excessive earth discharge or an increase in earth pressure due to insufficient earth discharge. . On the contrary, if the rotation speed of the screw blades 9, that is, the screw rod 8 is set so that the required amount of soil removal can be obtained when the geological conditions change, the desired agitation will not be performed this time. G
Will have an adverse effect on the improved quality of.

Alternatively, various screw blades 9 having different blade diameters and pitches are prepared in advance so that the required amount of soil can be secured while the screw rod 8 is operated at a rotation speed corresponding to the improved quality of the ground G. Although it is possible to do so, it is not practical to manufacture a large number of various types of screw blades 9 at a high cost.

In addition, the geological conditions of the ground G to be improved, that is, the soil quality, the void ratio in the ground, the amount of groundwater, etc. are not always uniform, but often differ depending on the depth. Therefore, even if the supply amount of the solidifying material slurry is changed depending on the depth depending on the geological conditions, as described above, it is not possible to change the amount of soil discharged by controlling the rotation speed of the screw blades 9 or the like correspondingly. In fact, it is impossible because the rotation speed of the stirring blade is preferentially set in consideration of the improved quality.

In this way, the improved quality of the ground G and the prevention of the earth pressure decrease due to the earth pressure increase or the excessive earth discharge,
It is extremely difficult to satisfy both purposes, though important for construction management.

The applicant of the present invention has previously filed Japanese Patent Application No. 7-1830.
As No. 91, it is possible to adjust the amount of soil discharged by the screw rod by changing the arrangement interval of the screw blades by providing a screwless shaft section without screw blades between the shaft sections with screws equipped with screw blades. Proposed. However, with this proposal,
By interposing a shaft section without a screw,
It has been found that the total length of the screw rod may become longer or shorter than the initially set length, which may cause inconvenience or hindrance in excavation work or the like.

The present invention has been made in consideration of the above points, and suppresses the rise and fall of earth pressure by performing earth removal commensurate with the geology without changing the overall length of the screw rod. An object of the present invention is to provide a ground improvement method and a ground improvement device that can improve the ground at a cost.

[0013]

The invention according to claim 1 is
Using a ground improvement device equipped with a screw rod having a spiral screw blade, an excavation stirring blade, and a solidifying material supply means having a solidifying material discharge port, solidify the ground to a predetermined depth with the excavating stirring blade. After digging without supplying the solidified material, the solidified material supply unit controls the supply amount of the solidified material per unit time according to the geological conditions of the ground, and supplies the solidified material into the ground from the solidified material discharge port. Along with stirring and mixing the solidifying material and the earth and sand in the ground with the excavation and stirring blade, the soil is discharged to the ground by surplus earth and sand in the ground according to the amount of the solidifying material supplied by the screw rod. When improving, in advance, set a predetermined amount of earth removal per unit time when rotating the screw rod at a predetermined rotation speed according to the geological conditions of the ground to be improved, the predetermined amount of earth removal Will be Wherein the helical screw blade fragment or intermittently screw with shaft with a least 1 ground improvement method which by a shaft connected to constitute the screw rod, disk of the soil improvement device
The drill stirring blade and the solidified material discharge port are located above the Liu rod.
It is provided below, and the ground is set by the excavation stirring blade
After excavation to a certain depth, the excavation stirring blades on the upper side
Discharge of the solidified material on the lower side until the introduced depth is reached.
While supplying solidification material into the ground from the mouth,
The stirrer is used to stir and mix the solidifying material and the soil in the ground.
Down from the solidified material discharge port on the upper side.
In addition to supplying the solidifying material into the board,
Lifted while stirring and mixing the solidifying material and the soil in the ground.
Characterized by discharging soil with the screw rod
There is. Further, the invention according to claim 2 is characterized in that, while lifting the screw rod at a constant speed and rotating the screw rod at a constant speed, surplus earth and sand in the ground is discharged to the ground according to the amount of the solidified material supplied.

As described above, when the ground is improved by using the ground improvement device, the spiral screw blades are fragmented or intermittently beforehand according to the geological condition for each depth of the ground to be improved. At least one shaft with a screw provided was connected to form a screw rod so that a predetermined amount of soil was discharged, and the amount of solidifying material supplied per unit time by the solidifying material supply means was controlled. Then, in the case of geological conditions in which the amount of the solidifying material to be supplied is large, the arrangement interval of at least one portion of the screw blades arranged in a fragmentary or intermittent manner is made small, and the geological condition in which the amount of the solidifying material to be supplied is small. In this case, conversely, the screw rod is configured so that the arrangement interval of at least one location of the screw blade is large. Then, while supplying the solidified material in an amount corresponding to the ground conditions by the solidified material supply means, the screw rod is pulled at a constant speed and rotated at a constant speed, the solidified material supply amount and the soil discharge amount are geologically determined. It is possible to adapt to the conditions.

The invention according to claim 3 is the invention according to claim 1 or 2.
The ground improvement method described above is characterized in that the screw rod is configured such that the arrangement interval of the screw blades is changed so that the predetermined amount of soil is discharged.

As a result, for example, in the case of using a screw rod in which a shaft with a screw having a small arrangement interval of screw blades is located in the upper portion,
It is possible to secure a larger amount of soil discharged in the upper portion than in the lower portion, and it is possible to prevent the soil pressure from rising in the upper portion due to the upward movement of soil for soil discharging from the lower portion.

The invention according to claim 4 is the invention according to claim 1 or 2.
The ground improvement method described above is characterized in that the screw rod is configured such that the pitch of the screw blades is changed to achieve the predetermined amount of discharged soil.

As a result, when using the screw rod in which the pitch of the screw threads of the upper portion of the screw blade is set to be larger than that of the lower portion, the upper portion has a larger discharge amount than the lower portion. It is possible to secure a sufficient amount of soil, and it is possible to prevent an increase in soil pressure in the upper portion due to the upward movement of soil for soil discharge from below, as in the case of the invention described in claim 3.

The invention according to claim 5 is the invention according to claim 1 or 2.
The ground improvement method described above is characterized in that the screw rod is configured so that the outer diameter of the screw blade is changed to achieve the predetermined amount of discharged soil.

As a result, when a screw rod in which the outer diameter of the screw blade in the upper part is set to be larger than that in the lower part is used, the upper part has a larger amount of soil discharged than the lower part. Therefore, it is possible to prevent the rise of the earth pressure in the upper portion due to the soil discharge from below, as in the invention according to claim 2 or the invention according to claim 3 described above.

According to a sixth aspect of the present invention, a screw rod rotatably driven about an axis and vertically movable, and an excavator which is vertically provided at a tip of the screw rod and excavates the ground while stirring the ground. A stirrer blade, a solidification material supply mechanism having a solidification material discharge port for supplying the solidification material to the ground, which is provided in the vicinity of each of the upper and lower excavation stirring blades, and the supply of the solidification material by the solidification material supply mechanism A control unit for controlling the amount, wherein the screw rod is detachably connected to at least one shaft with a screw provided with spiral screw blades on the outer peripheral surface of the tubular body in a fragmentary or intermittent manner. It is characterized by being said.

As a result, the ground can be improved to a predetermined quality according to the geological conditions of the ground. Further, when providing a shaft with a screw provided with spiral screw blades in a fragmentary or intermittent manner according to the geological conditions of the ground to be improved, in other words, the supply amount of the solidifying material, at least 1
By setting the placement interval of the screw blades at a suitable value, the screw rod can be configured to achieve a predetermined amount of soil removal, and the amount of soil removal can be adjusted or set according to geological conditions. be able to. Supply of solidifying material
And the amount of soil discharged can correspond to the geological conditions.
It becomes Noh. In addition, the ground improvement apparatus can be used as an optimum configuration for other sites having different geological conditions only by changing the arrangement interval of at least one screw blade according to the geological conditions of the ground to be improved.

According to a seventh aspect of the present invention, in the ground improvement device according to the sixth aspect , the screw blade can be moved in the axial direction with respect to the pipe body.

[0024] Thus, the screw blades can be moved in the axial direction according to the geological conditions of the ground, whereby the arrangement intervals of the screw blades can be set arbitrarily, so that even with one type of screw shaft, the geology of the ground Various screw rods can be used depending on the conditions.

[0025]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the first to fourth embodiments shown in the drawings.

[First Embodiment] First, in the first embodiment, the arrangement intervals of the screw blades of the shaft with a screw included in the screw rod are made constant, and the pitch of the screw blades is made constant. Figure 1
FIG. 3 shows a ground improvement device according to the present invention.

As shown in FIG. 1, the ground improvement device 10 includes
A boring / stirring mechanism 1 for boring and agitating the ground G in a main body (not shown) equipped with an endless track caterpillar for movement 1
1 is configured to be lifted and lowered by an elevator mechanism (not shown). The drilling / stirring mechanism 11 includes two screw rods 12 and 12, and each screw rod 12
Stirring blades (excavation stirring blades) 13 and 14 provided at the lower end of the
It has a schematic configuration including and.

The upper ends of the screw rods 12 and 12 are connected to and supported by a driving motor (driving source) 16 via a speed reducer (not shown). By driving the driving motor 16, Each screw rod 12
Is driven to rotate around the axis. Also,
An interference band 1 is provided at the lower end of the screw rods 12, 12.
8 are provided so as to maintain the distance between them.

Each screw rod 12 has an interference band 1
8 is a shaft 19 with a screw formed by forming screw blades 19b spirally arranged with a constant outer diameter on the outer peripheral surface of the tubular body 19a for discharging the stirred earth and sand. A plurality of units are connected so as to be coaxial with each other. The screw blades 19b of the shaft 19 with a screw are formed in a substantially one-turn shape, and are arranged at regular intervals d, that is, so-called intermittently arranged. Then, when setting the constant interval d, a soil removal amount test is performed in advance at a predetermined lifting speed and rotation speed, and is set based on the data obtained therefrom.
The screw shafts 19, 19, ... Are removably connected by an appropriate joint mechanism (not shown).

The stirring blades 13 and 14 are provided so as to be orthogonal to each other in a plan view. Lower end stirring blade 13
Bit 1 for efficiently agitating the ground G at the tip of the
3a, 13a, ... Are provided.

The blades of the stirring blades 13 and 14 are provided with solidifying material discharge ports 22 for discharging a solidifying material such as cement slurry. One end of a slurry hose or slurry pipe (not shown) that passes through the screw rod 12 is connected to each solidified material discharge port 22. The other end of this slurry hose (not shown) is manufactured by kneading and manufacturing cement slurry with a predetermined composition, and is also provided with a controller for supplying a predetermined amount of cement slurry based on previously input data. It is connected to a device (not shown). A solidification material supply mechanism (solidification material supply means) 23 is constituted by the solidification material discharge port 22, the slurry hose (not shown), and the slurry manufacturing device (not shown).

In this solidifying material supply mechanism 23, cement slurry produced by a slurry producing apparatus (not shown) is sent out as needed, and this is ejected from the solidifying material discharge port 22 through a slurry hose (not shown). Has become.

Next, the ground improvement device 1 having the above-mentioned structure.
An embodiment of the ground improvement method when 0 is used will be described. For this purpose, the control unit (not shown) of the solidifying material supply mechanism 23 is preliminarily based on the geological conditions of the ground G to be improved, that is, various data such as soil quality, underground void ratio, and groundwater volume.
Input the cement slurry supply amount data.
Also, based on this cement slurry supply amount data,
With the stirring blades 13 and 14 reaching the predetermined deepest depth, the shaft 19 with screw up to the ground surface G1 of the ground G
The number of shafts with screws 19, 19, ... Is determined so that the screw blades 19b of FIG.

Then, in order to actually perform the ground improvement work,
First, at a predetermined location of the ground G, the screw rod 12,
Position 12 Next, by rotating the screw rods 12 and 12 in the direction indicated by reference numeral (a) in the drawing by the drive motor 16, the stirring blades 13 and 14 are rotated and the drilling / agitation mechanism 11 is grounded by its own weight. Go into G and continue to dig.

In this way, when the ground G is cut to a predetermined depth by the stirring blades 13 and 14, the drilling / stirring mechanism 1
Stop the descent of 1.

Next, the slurry manufacturing apparatus side (not shown)
While discharging the cement slurry stored in the ground into the ground G from the solidifying material discharge port 22 provided at the blade base of the stirring blades 13, 13 below the screw rods 12,
The stirring mechanism 11 is further lowered and the drilling by the stirring blades 13 and 14 is continued. At this time, the cement slurry discharged from the solidifying material discharge port 22 is stirred and mixed with the soil in the ground G by the stirring blades 13 and 14.

After this, the stirring blades 14, 1 located on the upper side
When 4 reaches the depth where the solidified material has been introduced, drilling
The lowering of the stirring mechanism 11 is stopped. Then, if necessary, the cement slurry is introduced into the ground G from the solidifying material discharge ports 22 and 22 provided at the blade bases of the lower stirring blades 13 and 13 with the screw rods 12 and 12 being rotated. The tip is processed by ejecting for a certain period of time.

After the completion of the above-mentioned tip treatment, the discharge port of the cement slurry is switched to the solidified material discharge ports 22, 22 provided at the bases of the stirring blades 14, 14. Then, while raising the boring / stirring mechanism 11, by the stirring blades 13 and 14, the solidifying material discharge port 22 provided at the base of the stirring blades 14 and 14,
The cement slurry discharged from 22 is stirred and mixed with the soil in the ground G, and the drilling / agitation mechanism 11 is pulled up. At this time, the discharge amount of the cement slurry from the solidifying material discharge ports 22 and 22 is controlled according to the geological condition of the ground based on the supply amount data previously input to the control unit.

On the other hand, in the screw rods 12 and 12, the rotation of each screw blade 19b and the screw rod 1 after the stirring blades 13 and 14 reach a predetermined depth.
Due to the lifting of Nos. 2 and 12, the earth and sand in the portion of the shaft with screw 19 is moved upward. Further, the earth and sand in the portion of the shaft 19 with screw without the shaft blade 19b is pushed up by the earth and sand which is lifted by the shaft blade 19b which is moved from below, and the earth pressure is kept substantially constant. It is excreted while being soiled. Then, the earth and sand moved upward by the rotation and lifting of the screw rods 12 and 12 in this way is not particularly affected by the screw blades 19b of the shaft 19 with a screw located above the ground surface G1 especially in the vicinity of the deepest portion. It is sure to be discharged to the surface at.

As described above, the hydration reaction of the cement slurry discharged into the ground G and stirred and mixed with the earth and sand, the ion exchange action between the hydration product of the hydration reaction and the clay mineral, or the pozzolanic reaction The soil is chemically solidified by the chemical consolidation reaction mainly composed of, etc., whereby a columnar improved pile is formed in the ground G. At this time, the volume expansion of the ground G by the supply of the cement slurry by the discharge of a predetermined amount by the screw rods 12, 12 configured as described above and the supply of the solidifying material according to the geological condition,
It suppresses the rise of soil pressure and also prevents the decrease of soil pressure due to excessive soil removal.

After that, the above steps are repeated to sequentially form a predetermined number of improved piles at other predetermined positions to complete the improvement of the ground G.

In the ground improvement method described above, the amount of cement slurry supplied by the solidifying material supplying mechanism 23 is controlled in accordance with the geological conditions of the ground G, and the predetermined amount is also specified in accordance with the geological conditions of the ground G to be improved. The screw rod 19b provided on the shaft 19 with screw or the arrangement distance d between the screw blades 19b provided on the shaft with screw 19 or the arrangement distance d between the screw blades 19b of the shafts with screw 19 adjacent to each other is set to a constant value so that the amount of soil is discharged. 12 and 12 are configured. In this way, the soil is improved to a high quality as a whole by adopting the screw rods 12 and 12 which are set so as to achieve a predetermined amount of soil discharge corresponding to the geological conditions of the soil G. It becomes possible.

That is, since the screw blades 19b are arranged intermittently, as shown in FIG. 5, the earth discharging function is reduced as compared with the case where the screw blades 19b are arranged continuously. This is a screw wing 19 that is approximately one roll.
Even if b pushes the excavated soil upwards, if the screw blades 19b above it are outside the range of influence of the pushing force, that is, if the distance d between the screw blades 19b is larger than a certain value, the excavated soil will move upwards. Unable to move to
It just rotates in the same position. Further, the pushing force itself can be reduced by reducing the outer diameter of the screw blade 19b having a substantially one-turn shape. On the other hand, screw wing 1
If the distance d between the 9b's is smaller than a certain value, an appropriate amount of excavated sand can be moved upward when a pushing force is required. Therefore, if the outer diameter of the screw blade 19b and the interval d thereof are optimally selected, the amount of soil discharged can be optimized while maintaining the rotation of the screw rod 12 at a predetermined value.

Under a geological condition in which a large amount of cement slurry is supplied and in a geological condition in which a small amount of cement slurry is supplied, the amount of soil to be discharged is controlled by changing or adjusting the interval d between the screw blades 19b. The amount of soil removed can be adjusted. In this way, the rise of soil pressure and the fall of soil pressure due to excessive soil removal are prevented, and the cause of adversely affecting existing surrounding underground structures and neighboring ground is eliminated. It is possible to prevent the load from being applied or earth pressure to be applied to neighboring structures.

Further, at the deepest depth, the screw rods 12 and 12 are configured so that the shaft 20 with a screw is positioned to a position above the ground surface G1 of the ground G. As a result, it becomes possible to reliably discharge the soil near the ground surface G1 when the cement slurry is supplied to the deepest portion where the earth pressure is the largest, and the screw blades 8 are located near the ground surface G1 as in the conventional ground improvement device 1 '. It is possible to suppress an increase in earth pressure near the ground surface G1 that occurs when the ground pressure is not formed up to 1 and to reduce the deep earth pressure. Therefore, with such a configuration, it is possible to prevent adverse effects due to an increase in earth pressure on various pipes and structures often buried in the vicinity of the ground surface G1.

In the first embodiment described above, a joint mechanism (not shown) is provided between the shafts 19 with screws, and the shafts 19 are connected to form the screw rod 12. The joint mechanism is not limited to this position, and may be provided at any position as needed.

Further, in the above-described first embodiment, only the plurality of screw shafts 19 in which the screw blades 19b are intermittently arranged are connected to each other to connect the screw rod 12 to each other.
However, the present invention is not limited to this, and FIG.
The screw shaft 19 having the screw blades 19b intermittently arranged is connected between the screw shafts provided so that the screw blades 19b shown in FIG. Good.

Further, in the above-described first embodiment, the screw blade 19b having a substantially one-turn shape is intermittently arranged on the outer periphery of the shaft 19 with a screw, but the invention is not limited to this, and the screw blade 19b is not limited thereto. May be two-winding or three-winding, and the screw blades 19b may be arranged in pieces so as to form one-half or less one-half winding or three-fourth winding.

[Second Embodiment] Next, the second embodiment of the present invention will be described.
An embodiment of is shown.

In this embodiment, as in the case shown in FIG. 1, two screw rods are provided below the hole drilling / agitation mechanism 11, but in FIG. The attached shaft 30 is shown. The shaft 30 with a screw shown here is configured such that the screw blade 30b is separate from the tube body 30a, and the screw blade 30b can be moved in the axial direction of the tube body 30a.

Specifically, the screw blades 30b are fixed to the outer periphery of the tubular body 30a with a small amount of play, and the short blade 31 is fixed to the outer periphery of the short pipe 31 by an appropriate fixing means such as welding. Short tube 3 consisting of a single screw piece 32
1 is moved to an appropriate height position with respect to the pipe body 30a, and then fixed to the pipe body 30a by a plurality of fixing bolts 33, ...

According to the shaft 30 with screw, the screw blade 30b can be freely moved in the axial direction with respect to the pipe body 30a, so that a predetermined amount of soil is discharged according to the geological conditions of the ground. The distance d between the screw blades 30b can be adjusted and set. That is, although the shaft 30 has one type of screw, various screw blades 30b depending on the geological conditions of the ground are provided.
Can be freely changed to a screw rod having an arrangement interval of.

In the above-described second embodiment, the screw blade 30b is simply fitted to the outer periphery of the tube body 30a and fixed by the bolt 33, but the invention is not limited to this, and the tube body 30a is not limited thereto. Between the outer periphery and the inner periphery of the screw blade 30b, a groove groove and a protrusion extending in the axial direction (longitudinal direction) corresponding to each other may be provided, and the rotation preventing structure may be formed by fitting them.

[Third Embodiment] Next, a third embodiment of the ground improvement apparatus and the ground improvement method according to the present invention will be described. The difference between the ground improvement device of the third embodiment and the ground improvement device of the first embodiment described below is that the arrangement intervals of the screw wings 40b of the shaft 19 with a screw forming the screw rod 42 are different. The point is that it is changed according to the height position of the screw rod 42. In the following description, the same components as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. This point is the same as in the fourth embodiment described later.

As shown in FIG. 3, the ground improvement device 40 has
Similar to the first embodiment, the drilling / agitation mechanism 11 provided so as to be vertically movable has two screw rods 42, 4
2, the stirring blades 13 and 14, and the solidifying material supply mechanism 23 have a schematic configuration.

Each of the screw rods 42 is constructed by connecting the shafts with screws 19 coaxially with each other by a joint mechanism (not shown). As the shaft 19 with a screw, a screw blade 40b shown in FIG. 3 is provided separately from the screw blade 40a, and the screw blade 40b is configured to be movable in the axial direction of the pipe 40a. The arrangement interval of the screw blades 40b is set to be narrower as the height of the screw rod 42 is higher.

The setting of the arrangement interval between the screw blades 40b is determined on the basis of the data obtained at this time by conducting a soil removal amount test at a predetermined lifting speed and rotation speed.

FIG. 3 shows an example thereof. That is, the total length of the shaft with screw 19A located at the bottom is m
, The distance between the lower end connected to the interference band 18 and the upper screw blade 40b is 1/2 · d ₁ (here, d ₁ = 1/2 · m), and the screw blade 40b and the upper side thereof. The distance between the screw blade 40b and the screw blade 40b is set to d ₁ , and the distance between the upper screw blade 40b and the upper end of the shaft 19 with screw is set to 1/2 · d ₁ . Further, in the shaft 19B with a screw in the center, the distance between the lower end of the shaft and the upper screw blade 40b is 1/2 · d _2.
(Where d ₂ = 1/3 · m), the screw blade 40 b
The spacing between the screw blade 40b of the upper d _2, the interval between the upper end of the upper screw blade 40b and the screw with shaft 19 is set to 1/2 · d _2. Further, in the shaft 19 with a screw located at the uppermost portion, the lower end of the shaft and the upper screw blade 40b of the shaft are provided.
And the distance is 1/2 · d ₃ (here, d ₃ = 1/4 · m), the distance between the screw blade 40b and the upper screw blade 40b is d ₃ , the upper screw blade 40b and the shaft with screw. The distance from the upper end of 19 is set to 1/2 · d ₃ .

Next, the ground improvement device 40 having such a configuration.
An embodiment of the ground improvement method using the above will be described. For this purpose, a control unit (not shown) of the solidifying material supply mechanism 23 is prepared in advance corresponding to the geological condition of the ground G to be improved.
Input the cement slurry supply amount data.
Then, the screw rods 12 and 12 are configured by setting the positions of the screw blades 40b with respect to the tubular body 40a as described above so that the amount of discharged soil corresponds to the supplied amount data of the cement slurry. For example, the amount of cement slurry supplied should be balanced with the amount of soil discharged.
The screw blades 19b are configured by setting an arrangement interval between them.

Thereafter, in exactly the same manner as in the first embodiment, after excavation to a predetermined depth by lowering the stirring blades 13 and 14 and tip treatment by the solidifying material supply mechanism 23, etc., it is put into the ground. Stirring blades 13 and 1 for the supplied cement slurry
The soil G is improved by discharging the soil by rotating and lifting the screw rods 42 while mixing and stirring in 4.

At this time, when the soil is discharged by the screw rods 42, 42, the shaft 19 with screw is used.
The arrangement intervals of the screw blades 40b of A, 19B, and 19C are different, and the smaller the arrangement interval is,
The soil removal function is increased.

In the ground improvement method described above, the arrangement interval of the screw blades 19b is appropriately changed / adjusted in accordance with the difference in the geology of each site of the ground G to be improved, as in the first embodiment. By doing so, even in the case of a site where the geological conditions of the ground G to be improved are greatly different, the amount of discharged soil can be changed according to the difference, and thus the earth pressure is not increased. In addition to the fact that the ground can be improved with high quality as a whole, in addition to this, in this embodiment, the arrangement interval between the screw blades 40b is set to be narrower as the height of the screw rod 42 becomes higher. Therefore, the upper portion of the ground G can secure a larger amount of soil discharged than the lower portion, and it is possible to prevent the soil pressure from rising in the upper portion due to the soil discharged from below. Earth removal work In, it is possible to discharge earth at substantially the same soil pressure state from the lower end of the drilling by pressing the earth pressure rise in the relatively high tend upper portion to the ground surface.

[Fourth Embodiment] Next, a fourth embodiment of the ground improvement apparatus and the ground improvement method according to the present invention will be described. The difference between the soil improvement device according to the fourth embodiment and the soil improvement device according to the first embodiment described below is that the screw threads of the shaft 55 with a screw forming the screw rod 52 are screw threads of the screw blade 53b. Pitch
The point is that the screw rod 52 is changed according to the height position thereof.

As shown in FIG. 4, the screw rod 52
Is composed of a plurality of screw shafts 53 coaxially connected to each other by a joint mechanism (not shown). The shaft 53 with a screw is a tubular body 53a.
A plurality of screw blades 53b formed in a spiral shape on the outer peripheral surface of the blade with a constant outer diameter for discharging the stirred sand
Are attached at predetermined intervals along the axial direction of the tubular body 53a. Here, all of the plurality of screw blades 53b provided are not necessarily formed into one winding shape. That is, as shown in FIG. 4, the uppermost screw blade 53b is formed into one winding, the lower screw blade 53b is formed into one winding half, and the lower screw blade 53b is formed into two windings. Has been done.

At the same time, the pitch P (P1, P2, P3) of the screw threads of the screw blade 53b is not constant, and when the length of the shaft portion to which the screw blade 53b is attached is m, the uppermost screw blade is formed. 53b pitch p
1 is m, and the pitch p2 of the screw blade 53b below is 2
/ 3 · m, and the pitch p3 of the screw blades 53b below it is set to 1/2 · m. That is, the pitch P of the screw threads of the screw blade 53b is set to increase as the height of the screw rod 52 increases.

The shaft 5 with screw shown in the figure
The shaft 53 with a screw connected to the upper side of 3 and the shaft 53 with a screw connected to the lower side of the screw rod 52 are similar to those described above.
Is set so that the pitch P of the screw threads of the screw blade 53b becomes smaller and the number of turns increases as the height of the blade becomes lower.

Here, the outer diameter of each screw blade 53b is set to the same value. In addition, the length of the intermediate shaft 54 and the pitch p of the screw blades 53b are set in advance by performing a soil removal amount test at a predetermined lifting speed and rotation speed, and determining the data based on the test.

According to the ground improvement method using the ground improving apparatus having such a structure, when the soil is discharged by the screw rod 52, if the pitch of the thread of each screw blade 53b of the screw shaft 53 is large. The larger the value, the more the soil discharge function increases. Therefore, in the ground improvement method described above, it is possible to secure a larger amount of soil discharged in the upper portion of the ground than in the lower portion, and it is possible to prevent the soil pressure from rising in the upper portion due to soil discharged from below. Therefore, during the earth unloading operation, the earth can be discharged from the lower end of the drilled hole to the ground surface under substantially the same earth pressure condition.

In the third embodiment and the fourth embodiment described above, the outer diameters of the screw blades 40b and 53b are not changed, and the arrangement intervals of the screw blades or the pitch of the screw threads are set to the screw rod. However, the outer diameter of the screw blade may be changed by changing the arrangement interval of these screw blades or the pitch of the screw threads, or by overlapping them.

[0070]

As described above, according to the ground improvement method of the first and second aspects, when the ground is improved by using the ground improving device, it is necessary to meet the geological conditions of the ground to be improved in advance. By connecting at least one shaft with a screw equipped with screw blades in a fragmentary or intermittent manner to configure a screw rod so that a predetermined amount of soil is discharged, and the ground is defined by the excavation stirring blade. After digging without supplying the solidifying material to a certain depth, the solidifying material supplying means controls the supply amount of the solidifying material per unit time according to the geological conditions of the ground to solidify into the ground from the solidifying material discharge port. While supplying the material, while stirring and mixing the solidified material and the earth and sand in the ground by the excavation and stirring blade, the excess earth and sand in the ground is discharged to the ground according to the amount of the solidified material supplied by the screw rod. Ground An improved method, the soil improvement instrumentation
On the screw rod of
The outlets are provided at the top and bottom, and the ground is mixed with the excavation and stirring blades.
After excavating to the specified depth, the upper excavation stirring blade
The solidification material on the lower side of the
While supplying the solidified material into the ground from the chemical material discharge port,
The solidification material and the soil in the ground are agitated by the excavation and agitation blade.
Lower while mixing, and then discharge the above solidified material
While supplying solidification material into the ground from the mouth,
The stirrer is used to stir and mix the solidifying material and the soil in the ground.
The ground is improved by pulling up one and discharging the soil with the screw rod . In this way, it is possible to improve the ground to a high quality according to the geological conditions at each site. Then, by setting the arrangement interval of at least one place of the screw blade to an appropriate value, it is possible to perform a predetermined amount of earth removal according to the supply amount of the solidifying material. Therefore, it is possible to prevent the earth pressure from rising and falling, and prevent the surrounding existing underground structures from being adversely affected, and preventing the ground surface from rising or sinking. Therefore,
It is also possible to omit adjacent protection work such as providing a buffer hole or groove for protection between the ground improvement area and the existing structure or the adjacent land even in the close proximity to the existing structure. In addition, as a result that the adjacent protection work can be omitted, it is possible to perform the ground improvement in close contact with the existing structure or the adjacent land.

According to the ground improvement method of the third aspect , the screw rod is constructed by changing the arrangement interval of the screw blades. As a result, in a portion where the solidifying material is supplied in a particularly large amount, for example, in the soft ground portion, by setting the arrangement interval of the screw blades located at the uppermost portion of the screw rod to be small, a larger amount of the solidified material is discharged near the ground portion. Since it is possible to secure a sufficient amount of soil, it is possible to remove soil from the lower end of the drilled hole to the ground surface under substantially the same soil pressure condition when constructing the deepest part, which in turn enables smoother soil removal. . As a result, the effects according to the inventions of claims 1 and 2 can be made more remarkable.

According to the ground improvement method of the fourth aspect , the screw rod is constructed by changing the pitch of the screw threads of the screw blade. As a result, by setting the pitch of the threads of the screw blades located at the top of the screw rod to a large value, a larger amount of soil can be secured in the vicinity of the above-ground part, especially in the part where the amount of solidified material supplied is large Therefore, at the time of construction of the deepest part, it is possible to remove the soil from the lower end of the drilled hole to the ground surface under substantially the same earth pressure condition, and thus to enable smoother soil removal.
As a result, smoother soil unloading becomes possible as in the case of the third aspect of the invention .

According to the ground improvement method of the fifth aspect , the screw rod is constructed by changing the outer diameter of the screw blade. As a result, in the part where the solidifying material is supplied in a particularly large amount, by setting the outer diameter of the screw blade located at the uppermost part of the screw rod to a large value, it is possible to secure a larger amount of soil discharge near the ground portion. Therefore, it is possible to discharge the earth from the bottom end of the drilled hole to the ground surface in the substantially same earth pressure condition at the time of construction of the deepest part.
Smoother soil removal is possible. As a result, claim 3
Alternatively, as in the case of the invention described in 4, the smoother soil removal becomes possible.

According to the soil improvement device of the sixth aspect , the screw rod is provided so as to be rotatable about the axis and vertically movable, and the tip of the screw rod is vertically provided to stir the soil. An excavating stirring blade for excavating while
A solidified material supply mechanism having a solidified material discharge port for supplying the solidified material into the ground, which is provided near each of the upper and lower excavating and stirring blades, and controls the amount of the solidified material supplied by the solidified material supply mechanism. And a screw shaft provided with screw blades on the outer peripheral surface of the tubular body in a fragmentary or intermittent manner so that at least one shaft is detachably connected to the screw rod. According to the geological conditions of the ground, it is possible to appropriately set the arrangement intervals of the screw blades at predetermined locations, and it is possible to realize the ground improvement method according to claim 1 exhibiting the above-mentioned effects according to the geological conditions of each site. it can.

According to the ground improvement device of the seventh aspect , the screw blades can be moved in the axial direction with respect to the pipe body. Therefore, it is possible to freely set the arrangement interval between the screw blades, and it is possible to freely change to various screw rods according to the geological conditions of the ground, even though it is a shaft with only one type of screw, it is versatile. It is rich and economically very advantageous as compared with the case where a screw rod having various arrangement intervals of screw blades is used in advance.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a ground improvement device showing a first embodiment of the present invention.

FIG. 2 shows a second embodiment of the present invention,
(A) is a side view, (b) is sectional drawing which follows the BB line of (a).

FIG. 3 is a vertical sectional view of a ground improvement device showing a third embodiment of the present invention.

FIG. 4 is a side view of essential parts of a ground improvement device showing a fourth embodiment of the present invention.

FIG. 5 is a side sectional view showing an example of a conventional ground improvement method and ground improvement device.

FIG. 6 is a vertical cross-sectional view showing another example of a conventional ground improvement method and ground improvement device.

[Explanation of symbols]

10,40 Ground improvement device 11 Drilling and stirring mechanism 12, screw rod 13,14 Stirring blade (excavation stirring blade) 19,30,53 shaft with screw 19a, 30a, 53a tubular body 19b, 30b, 40b, 53b Screw blade 22 Solidified material discharge port 23 Solidifying material supply mechanism (solidifying material supply means) 31 Short tube 32 screw pieces

Front Page Continuation (72) Inventor Kazuyoshi Uemura 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Hisayuki Matsumoto 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Stocks In-house (72) Inventor Shinichi Nishimura 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Yoshihiko Tachida 1-2-1 Taito Taito-ku, Tokyo Within Fudo Construction Co., Ltd. ( 72) Inventor Katsuhide Sugiyama 1-2-1, Taito, Taito-ku, Tokyo Fudo Construction Co., Ltd. (72) Inventor Minoru Yamamoto 1-2-1, Taito, Taito-ku, Tokyo Fudo Construction Co., Ltd. (72) Inventor Fukuda Kosei 6-13-7, Akasaka, Minato-ku, Tokyo Within Tennox Co., Ltd. (72) Inventor Kamifumi Kagami 6-13-7 Akasaka, Minato-ku, Tokyo Tenox, Inc. (72) Inventor Setsu Horikiri Tokyo 6-13-7 Akasaka, Minato-ku, Tokyo, Tenox Co., Ltd. (56) Reference JP-A-6-299538 (JP, A) JP-A-64- 6410 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02D 3/12

Claims (7)

(57) [Claims] 1. A ground improvement device including a screw rod having a spiral screw blade, an excavation stirring blade, and a solidifying material supply means having a solidifying material discharge port is used to define the ground by the excavating stirring blade. after excavation without supplying consolidated material to be depth, the solidification in accordance with the geological conditions of the ground
The supply amount of the solidifying material per unit time is controlled by the material supplying means to supply the solidifying material into the ground from the solidifying material discharge port, and the solidifying material and the earth and sand in the ground are stirred by the excavation stirring blades. While improving the ground by discharging the surplus soil in the ground to the ground according to the amount of solidified material supplied by the screw rod while mixing, in advance, according to the geological conditions of the ground to be improved A predetermined amount of soil discharged per unit time when rotating the screw rod at a rotation speed of 10 is set, and the spiral screw blades are provided in pieces or intermittently so that the predetermined amount of soil discharged is obtained. Ground improvement in which at least one shaft with a screw is connected to form the screw rod
It is a construction method, and the screw rod of the ground improvement device, the excavation stirring
The blade and the solidified material discharge port are provided on the top and bottom, and the ground was excavated to the specified depth by the excavation and stirring blade.
After that, the excavation stirring blade on the upper side reaches the depth where the solidified material has been introduced.
Until it solidifies from the solidified material discharge port on the lower side into the ground
While supplying the solidified material, the excavating stirring blade and the solidified material
While stirring and mixing the earth and sand in the ground, it is lowered, and then the solidified material is discharged into the ground from the solidified material discharge port on the upper side.
In addition to supplying the
While stirring and mixing the earth and sand in the ground, lift the
A soil improvement method characterized by soil removal using a Liu rod . 2. The ground improvement method according to claim 1, wherein the screw rod is lifted at a constant speed and is rotated at a constant speed, and excess soil in the ground is discharged to the ground according to the amount of solidified material supplied. Ground improvement method characterized by. 3. The ground improvement method according to claim 1 or 2 , wherein the screw rod is configured so that the predetermined amount of soil is discharged by changing the arrangement interval of the screw blades. Improved construction method. 4. The ground improvement method according to claim 1 or 2 , wherein the screw rod is configured so that the pitch of the screw threads of the screw blade is changed to achieve the predetermined amount of discharged soil. Ground improvement method to do. 5. The ground improvement method according to claim 1 or 2 , wherein the screw rod is configured so that the outer diameter of the screw blade is changed to achieve the predetermined amount of discharged soil. Improved construction method. 6. A screw rod rotatably driven around an axis and vertically movable, an excavation stirring blade vertically provided at a tip of the screw rod for excavating the ground while stirring, and A solidification material supply mechanism provided near each of the excavation and stirring blades and having a solidification material discharge port for supplying the solidification material into the ground, and a control unit for controlling the amount of the solidification material supplied by the solidification material supply mechanism. And the screw rod is configured to detachably connect at least one shaft with a screw provided with a spiral screw blade in a fragmentary or intermittent manner on the outer peripheral surface of the tubular body. A characteristic ground improvement device. 7. The ground improvement device according to claim 6 ,
The ground improvement device, wherein the screw blade is provided so as to be movable in the axial direction with respect to the pipe body.