JPH08302670A - Method and device for improvement of ground with horizontal cutter in working with large depth - Google Patents

Abstract

PURPOSE: To excavate the ground to a large depth and equip a sustaining force to the earth by removing gravel from the excavated soil, returning muddy soil into the excavation hole, supplying a ground stabilizing material after completion of the excavating process, and agitating and mixing with the muddy soil in the hole. CONSTITUTION: A column 2 fitted at the tip with a pair of cutter drums 1 is hung up, and the ground is excavated with these cutter drums 1 while a minor quantity of bentonite muddy water, etc., is supplied from a muddy water pump 15a through a mud supplying pipe 14, and the column 2 is descended with progress of excavation, and column units are spliced bit by bit. The excavated soil is discharged till a gravel separating device 12 through a mud lifting pipe 11, and gravel 18 is separately sent to a collecting chamber 19, and after the water content of the mud is adjusted in a preparing chamber 12a, the mud is sent back to the inner upper part of the excavation hole by another muddy water pump 12b through a mud feed pipe 12c. After excavating to the specified depth, agitation blades 7 are rotated, and the ground stabilizing material fed by pressure from upon the ground is supplied, and the agitation and mixing with the excavated soil are conducted. In the place where the column 2 has been drawn off, an improved earth 20 is formed uniformly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention applies to underground 70m-100
The present invention relates to a ground improvement method for excavating the ground up to a large depth of about m to improve the ground to have a ground bearing capacity, and a horizontal cutter-type ground improvement device used for implementing the method.

[0002]

2. Description of the Related Art Conventionally, a ground improvement material (hereinafter referred to as a ground stabilization material) which is called as a stabilizing material, a hardening material, a solidifying material or the like is excavated on a soft ground and is excavated into an excavated soil at an in-situ (in a drill hole). .)
A ground improvement method and a ground improvement apparatus for injecting, stirring, mixing, and stabilizing are variously developed and implemented since about 1975, and many achievements are left. For example, Shoko 5
The inventions described in JP-A-8-10750 and JP-A-63-300110 are referred to.

Conventionally, as a measure for constructing a revetment foundation for a harbor located on a soft ground, for example, a ground improvement method and a device for deep ground improvement have been developed, but at present it can be improved. The maximum depth is only about 40m.

[0004]

The maximum depth that can be improved by the conventional ground improvement method and ground improvement device is about 40.
Since it is about m, there is a problem that it cannot be dealt with when the soft ground exists deeper in the vicinity of 70 to 100 m underground. Not only that, in the case of the conventional ground improvement device described above, the rotation axis (kerry bar) becomes longer in proportion to the depth of the ground improvement, and the base machine of the ground improvement machine that supports this becomes inevitable. It becomes too large and the cost of machinery and equipment becomes enormous, and there is a limit to the length of the rotating shaft, and it is often not applicable to land construction.

Further, the conventional ground improvement device has a construction of a horizontal propeller-type cutter and is mainly intended for improvement of sludge-like soft ground. Therefore, a gravel layer with an N value of 50 or more is underground. It is impossible to excavate or improve the ground where soft rocks exist. From this point of view, it is a cause of hindering deep ground improvement, which is often composed of various strata.

Further, in the improvement of the ground where gravel is mixed, gravel having a large specific gravity is deposited on the bottom of the drilling hole to cause an increase in the drilling torque of the stirring shaft, and the drilling is impossible at a large depth beyond the limit point. It has become a cause that makes it difficult to improve the ground for large depths. Therefore, an object of the present invention is to make it possible to improve the ground at a large depth of about 70 m to 100 m underground, shorten the working time of the improvement work, excavate, ensure vertical accuracy of stirring, and control easily.
It is an object of the present invention to provide a ground improvement method and a ground improvement apparatus that can reduce the cost of construction machinery and equipment and are economical.

[0007]

As a means for solving the above-mentioned problems, the invention described in claim 1 excavates the ground, injects the ground stabilizer into the excavated soil at the original position, and mixes by stirring. In the ground improvement method that stabilizes the ground, at the tip is provided a cutter drum with at least a pair of horizontal shafts, and a column with a stirring blade drum with horizontal shafts above it is suspended vertically from the ground, and the mast pipe is used to While excavating the ground with a cutter drum while supplying the bentonite muddy water etc. supplied from the muddy water supply device to the vicinity of the cutter,
As the excavation progresses, the pillar is lowered, a pair of cutter drums install a lift mud pump directly above the scraping soil, and the drilling soil is pumped by the lift mud pump to the ground gravel separator through the lift mud pipe. Discharging, removing gravel from the excavated soil in the gravel separation device, returning the remaining mud to the upper part of the excavation hole again by the mud pump, and after completing the excavation process to a predetermined depth, the stirring blade drum It rotates, and the ground stabilizer is supplied from the stabilizer supply device on the ground through the stabilizer supply pipe near the stirring blade drum to stir and mix with the mud in the excavation hole, and the columns are successively pulled up. And

According to a second aspect of the present invention, in a ground improvement method for excavating the ground, pouring a ground stabilizer into the excavated soil at the original position, and stirring and mixing to stabilize the ground, a cutter drum having at least a pair of horizontal shafts at the tip thereof. Suspend a column vertically from the ground, and excavate the ground with a cutter drum while supplying bentonite mud supplied from the mud supply device on the ground through a mud supply pipe to the vicinity of the cutter, and according to the progress of the excavation, the pillar , A pair of cutter drums install a lift mud pump at a position directly above to scrape the excavated soil, and the excavated soil is discharged to the upper side of the partition plate through the sludge pipe by the lift mud pump. After the excavation process is completed to the depth, the excavated mud is returned from the upper side of the partition plate to the part of the cutter drum by the reverse operation of the above-mentioned pump for further reduction. Stirring the mud by a cutter drum ground stabilization material from the ground of a stable material supply device supplies to the vicinity of the cutter drum through wood supply pipe, and mixed and, and, respectively, characterized in that raising the sequential post.

The partition plate according to the second aspect is partitioned into an umbrella shape that traverses the inside of the drill hole, and the inclination angle thereof is adjusted to adjust the flow rate from the top to the bottom of the drilling mud filled in the drill hole. By adjusting the pressure balance between the upper and lower parts. A gravel collecting basket is provided in the vicinity of the upper end opening of the sludge pipe according to claim 2 to remove large-sized gravel from the excavated soil.

A fifth aspect of the present invention is a ground improvement device that excavates the ground, injects a ground stabilizer into the excavated soil at the original position, and mixes and stirs it to stabilize, which is a pillar suspended vertically from the ground. At least a pair of horizontal axis cutter drums are provided at the tip of the, and horizontal axis stirring blade drums are provided at a position slightly above it, and the mud supply pipe connected to the above-mentioned mud water supply device is a cutter for bentonite mud water etc. The stabilizer supply pipe, which is connected to the pouring outlet that supplies from the vicinity of the drum and is connected to the stabilizer supply device on the ground, is connected to the pouring outlet that supplies the ground stabilizer to the vicinity of the stirring blade drum, and excavates the ground. According to the progress of, the pillars will be sequentially added,
A lift mud pump is installed directly above the pair of cutter drums to scrape excavated soil, the lift mud pump is connected to a ground gravel separator through a mud pipe, and gravel for removing gravel from the excavated soil. The separation device must be equipped with a mud pump that returns mud other than gravel to the upper part of the excavation hole again, and a mud pipe connected to the pump, and the agitating blade drum in the extraction process after excavating to a predetermined depth. It is rotated and stirred and mixed with the mud in the excavation hole while supplying the ground stabilizer from the stabilizer supply device on the ground through the stabilizer supply pipe to the vicinity of the stirring blade drum, and the columns are sequentially pulled up, Each of the raised columns is characterized by being sequentially separated.

The strut gripping device according to the fifth aspect is installed at the upper end opening of the excavation hole, and the upper end of the strut is suspended by a crane or the like on the ground. The invention of claim 7 is
It is a ground improvement device that excavates the ground and injects the ground stabilizer into the excavated soil at the in-situ, stirs and mixes it, and stabilizes it by at least a pair of horizontal shafts at the tip of the pillar vertically suspended from the ground. A mud supply pipe equipped with a cutter drum is connected to a mud supply device on the ground, and is connected to a spout that supplies bentonite mud and the like from the vicinity of the cutter drum. The sludge pump is installed directly above the pair of cutter drums to scrape the excavated soil, and the sludge pump is connected to the upper side of the partition plate through the sludge pipe. Has one end that can be tilted vertically with respect to the support, and the other end that is supported by an adjustment jack, and is connected to the stabilizer on the ground. The material supply pipe is connected to a spout that supplies the ground stabilization material to the vicinity of the cutter drum, and in the extraction process after excavating to a predetermined depth, the ground stabilization material is supplied while stirring and mixing with the mud by the cutter drum. And the columns are sequentially pulled up.

The mud pump according to claim 5 or 7 is a piston type pump. The mud pump described in claim 7 is a screw type mud pump.

[0013]

According to the first and fifth aspects of the invention, the pair of horizontal cutter drums can sharply excavate not only gravel ground having an N value of 50 or more, but also soft rock or other hard ground.
Therefore, it is possible to excavate the ground regardless of the stratum structure, so that it is possible to cope with the ground improvement at a large depth. For example, since it is possible to cut the connection surface with the already improved hard ground, it is easy to ensure the continuity and integrity of the improved ground.

The soil excavated by the cutter drum is immediately discharged to the above-mentioned gravel separation device by the sludge pump through the sludge pipe, so that the excavated soil does not get caught in the cutter drum. It does not cause resistance to the torque and the excavation force of the ground improvement device, and does not cause the inconvenience of gravel deposits. The remaining mud, from which gravel has been removed by the gravel separator, is adjusted to an appropriate water content ratio and returned to the upper part inside the drill hole, thus functioning to prevent collapse of the hole wall, and finally to the ground stabilization material. It becomes a mixed material and forms improved ground with good quality.

Since the soil is deeply improved, when the ground is excavated by the cutter drum, the thinnest possible amount of bentonite muddy water or the like is poured into the vicinity of the cutter to the extent of lubricating the excavation to avoid solidification of the excavated soil. In the extraction process after excavating the ground to a predetermined depth, the stirring blade drum is rotated and at the same time the soil stabilizer such as cement milk is injected from the vicinity of the stirring blade drum to agitate with the mud in the excavation hole, The mixing process can be performed sufficiently. By properly selecting the rotation directions of the cutter drum and the stirring blade drum, a levitation force is generated as a reaction between the interaction of these rotations and the downward movement of the mud in the drill hole, and the lifting resistance can be reduced.

Next, also in the case of the inventions of claims 2 and 7, the excavating action of the cutter drum is similar to that of claims 1 and 5. However, the discharge of excavated soil is on the upper side of the partition plate located within a short distance from the cutter drum in the excavation hole, and the head of the mud pump is small, so the capacity of the mud pump can be reduced and the screw type A pump is enough. Of course, the excavated soil is forcibly removed from the cutter portion, so that it does not cause an increase in the rotation torque of the cutter drum. The weight of the soil discharged to the upper side of the partition plate works as a digging force.

In the extraction process after excavating the ground to a predetermined depth, the cutter drum also functions as a stirring blade drum to efficiently and reliably stir and mix the excavated soil and the ground stabilizer, thereby improving the quality of the improved ground. make. When the mud pump returns the amount of excavated soil according to the pulling speed of the pillar from the upper side of the partition plate to the lower side, the pulling resistance of the cutter drum is reduced as a reaction, and pulling operation from a large depth is easy. Let's train.

[0018]

EXAMPLE An example of the present invention shown in the drawings will be described below.
1 and 2 show the outline of the ground excavation process and the pulling process from the deepest part in the ground improvement method by the ground improvement device of the first embodiment. Reference numeral 1 in the figure is a cutter drum for ground excavation, which is installed in a pair at the lower end of the support column 2. However, the number of pairs is not limited to one, and a plurality of pairs can be implemented. As shown in FIGS. 3 and 4 in detail, the cutter drum 1 has a configuration in which a large number of cutter bits are planted in a spiral arrangement in the axial direction on the outer peripheral surface of a rotating drum that rotates about a horizontal rotating shaft. . The pair of cutter drums 1, 1 are installed in an arrangement parallel to the horizontal direction in which the cutting edge circles (outer diameter circles) are in close contact with each other. In the case of the illustrated example, the pair of cutter drums are cantilevered by the bearing plate 3 at the center of each rotary drum, and each of the cutters is driven by two hydraulic motors 6 and 6 installed on the horizontal plate 5 directly above. The drums are individually driven synchronously so as to have the same peripheral speed. The upper end of the bearing plate 3 is integrally joined to the lower end of the column 2. The cutter drum 1 is rotationally driven by a hydraulic motor 6 via a rotary drive shaft arranged in the bearing plate 3.

Above the cutter drum 1, a pair of stirring blade drums 7, 7 are installed. Stirring blade drum 7
Is a configuration in which strip plate-shaped spiral blades are projected in multiple rows at regular intervals as an example of a stirring means for excavating soil on the outer peripheral surface of a rotating drum that rotates around a horizontal rotation axis. The stirring blade drum 7 is also supported by the bearing plate 3 in a cantilever manner at the center of the rotary drum. A pair of stirring blade drums 7,7
Are installed parallel to each other by a horizontal rotating shaft in the same direction as the above-mentioned cutter drums 1, 1, and each stirring blade drum is controlled by two hydraulic motors 9, 9 installed on the lower surface of the horizontal plate 8 directly below. They are synchronously driven individually at the same peripheral speed. A rotary drive shaft that connects the stirring blade drum 7 and the hydraulic motor 9 is also installed in the bearing plate 3.

Two units (however, not limited to two units) are provided at an intermediate portion between the pair of stirring blade drums 7 and 7 and directly above a vertical tangent line where the pair of cutter drums 1 and 1 scrape excavated soil. , Plural units are used.) Piston type mud pump 1
0 and 10 are arranged vertically downward, and the upper and lower plates 8 are
And is installed so as to penetrate the plate 5. The lower end of each lifting mud pump 10 is formed into a bell mouth-shaped suction port 10a which is widened toward the end. Further, a hydraulic jack 10b for driving a reciprocating piston (or a plunger) (not shown) in the cylinder is provided vertically downward on the upper portion of the sludge pump 10. Further, check valves 10c and 10d are provided at positions relatively below the cylinder body, directly below and just below the lower limit position of the reciprocating piston. That is, when the piston rises, the check valve 10c immediately below opens and sucks the excavated soil into the cylinder. At this time, the check valve 10d located right beside is closed. When the piston descends, the check valve 10c immediately below is closed,
The soil compacted in the cylinder is pushed out through the open check valve 10d right next to it. Lifting mud pipe 1 for guiding the soil
1'is connected to the outlet of the check valve 10d just beside. The two left and right lifting mud pipes 11 ′ are joined to one thick lifting mud pipe 11 at a position slightly above the lower end of the support column 2. The lift pipe 11 is arranged at the center of the support column 2 and is connected to the gravel separating device 12 on the ground. Therefore, the piston-type mud pump 10 is a model capable of pressure-feeding at least 70 m to 100 m or more in the pipe.

As shown in detail in FIG. 5, the column 2 is made of steel and has an H-shaped cross section, and the sludge pipe 11 is integrally arranged at the center of the web. There is. A plurality of hydraulic hoses 13, signal cables, control cables, etc. are arranged along one side of the web, and a mud supply pipe 14 for bentonite muddy water used for ground excavation along the other side, cement milk, etc. And a stabilizer supply pipe 14 ′ for supplying the ground stabilizer of FIG.
The lower portion of the stabilizer supply pipe 14 'is branched into two via a two-way valve 21, and each of them is connected to a withdrawal discharge spout 22 that opens at a position directly above the stirring blade drum 7 in the bearing plate 3. . In addition, the mud supply pipe 14 uses the hollow portion of the bearing plate 3 and is provided at the lower end of the bearing plate 3 for pouring and discharging 23 for penetration and discharge.
Connected with. The mud supply pipe 14 is connected to a muddy water supply device 15 on the ground, and bentonite muddy water or the like is discharged from the spout 23 at the tip of the bearing plate during the ground excavation process. The stabilizer supply pipe 14 'is connected to the ground stabilizer supply device 16 on the ground, and the ground stabilizer is discharged from the pouring port 22 slightly above the stirring blade drum 7 during the extraction process and mixed with the soil in the hole. , Stirred. The pillar 2 has a unit length of 10 in consideration of easiness of additional work and improvement of construction efficiency.
It is about 20 m, and the sludge pipe 11 is also integrally formed as a support unit. In order to facilitate the work of replenishing or separating the strut units, a strut gripping device 17 is installed at the mouth of the excavation hole on the ground. In addition, the code | symbol 25 in FIGS.
It is a protective cover that protects the check valve, etc. from mud.

The ground improvement method for large depths using the ground improvement device having the above structure is carried out as follows. In the ground excavation process, as shown in FIG. 1, a pillar 2 having a pair of horizontal cutter drums 1 at the tip thereof is vertically suspended by a ground leader or a crane (not shown), and a ground mud supply device is installed. The ground is excavated by the cutter drum 1 while supplying (penetrating and discharging) a very small amount of bentonite muddy water or the like that is pressure-fed by the muddy water pump 15a from 15 through the mud supply pipe 14 from the spout 23 near the cutter. The cutter drum 1 can be excavated sharply even if it is soft rock or the like. The pillar 2 is lowered as the excavation progresses. The support 2 is lowered by sequentially adding support units and operating a crane or the like to lower the support 2 by using its own weight. In the replenishing work of the strut units (also in the separating work), first, the upper end portion of the preceding strut is grasped by the strut gripping device 17 and the position is fixed. The column unit of the next rank is hung just above and the joining work is performed.

The excavated soil which is excavated by the pair of cutter drums 1 and 1 and scrapes up the soil is immediately passed through the sludge pipe 11 by the sludge pump 10 located immediately above to the ground gravel separating device 12.
To be discharged. The gravel separating device 12 separates the gravel 18 into a recovery tank 19 by, for example, a vibrating sieve system, and after appropriately adjusting the water concentration of the mud in the mixing tank 12a, the mud pump 12b pumps the mud inside the excavation hole through the mud pipe 12c. Return to the top.

In the extraction process after the excavation is completed to a predetermined depth, the stirring blade drum 7 is rotated as shown in FIG. 2, and the cement milk or the like which is pressure-fed by the muddy water pump 16a from the ground stabilizer supplying device 16 on the ground. The ground stabilizer is supplied from the pouring port 22 near the stirring blade drum through the stabilizer supply pipe 14 ', and the stirring and mixing process with the excavated soil is performed. Then, by operating a crane or the like, the support columns 2 are sequentially pulled up at an appropriate speed to proceed with the extraction process. In this case as well, the support columns are fixed by the support unit 17 for each joint position of the support unit, and the work of the previous support unit exposed to the ground is cut off. Thus, the improved soil 20 is uniformly formed in the excavation hole where the stirring blade drum 7 and the cutter drum 1 have risen.

[0025]

[Second Embodiment] Next, a ground improvement apparatus and a ground improvement method of the second embodiment shown in FIGS. 7 to 9 will be described. In the case of the present embodiment, as shown in FIG. 9, a pair of cutter drums 41, 41 is installed at the lower end portion of a column 40 having a rectangular tube structure in cross section. Prop 4 of this embodiment
0 is suspended by a crane wire 60 at its upper end by a crane on the ground. A central portion of the cutter drum 41 is supported in a cantilever manner by a bearing plate 42 protruding downward from the lower end of the column 40. Two hydraulic motors 44, 44 are installed in a machine room 43 formed at the lower end of the column, and the motors individually drive the cutter drums 41 synchronously so as to have the same circumferential speed. Also in the case of the present embodiment, as the transmission means for rotating the cutter drum by the hydraulic motor 44, the transmission shaft 61 is arranged inside the bearing plate 42, and transmission by the gear mechanism is adopted.

A plunger type (or piston type) mud pump 45 for sucking the excavated soil excavated and scraped by the cutter drums is vertically provided directly above the vertical common tangent line of the pair of cutter drums 41, 41. Multiple units are installed facing downward. A hydraulic jack 45c for reciprocating the plunger is installed on the upper part of the sludge pump 45,
A suction port 46 and a discharge port 47 are provided laterally at the piston lower limit position in the lower part of the cylinder, and check valves 45a and 45b are installed at the respective ports. Similarly to the mud pump of the first embodiment, the check valve 45a of the suction port is opened and the check valve 45b of the discharge port is closed during the suction stroke in which the plunger rises. On the contrary, the check valve 45a is closed and the check valve 45b of the discharge port is opened during the discharge stroke in which the plunger descends, and the soil compressed in the cylinder by the descending plunger is discharged from the discharge port. A lift pipe 48 is connected to each discharge port 47, and an upper end opening 48a of the lift pipe 48 which is vertically raised is located at a portion slightly above the partition plate 50 (a pumping distance is about 10 m). . Reference numeral 62 in FIGS. 7 and 8 is a gravel collection basket for collecting gravel in the excavated soil discharged from the upper end opening 48a.

The partition plate 50, which is easy to understand in FIG. 7, is shown in FIG.
It is shaped like an umbrella that divides the cross section of a hole to be excavated into a substantially square into two parts, the inner end at a position slightly above the machine chamber 43 and the sludge pump 45 at the lower part of the column 40. It is attached to the column 40 by a hinge 51 so as to be tiltable. Below the partition plate, an adjustment jack 53 whose base end is tiltably attached to a column by a hinge 52 is provided.
Is installed, and the tip end of its output shaft is connected to a substantially intermediate portion of the lower surface of each partition plate 50 by a hinge 54 in a pin state. As shown in FIG. 7, the partition plate 50 is normally supported by the adjusting jack 53 to partition the excavation hole in a state where the umbrella is opened with a downward inclination of about 45 °. Reference numeral 55 shown in FIGS. 7 to 9 is a control plate for abutting against the hole wall of the excavation hole to receive a reaction force and to secure and adjust the verticality of the support column 40. The control plate 55 is a means for adjusting the vertical accuracy of the support column 40 by applying a reaction force to the hole wall, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-185817. The control plate is also used in the first embodiment described above, if necessary.

In the case of the present embodiment, the mud supply pipe or the stabilizer supply pipe is provided at a position just below the machine chamber 43 at the lower end of the support column 40 in the same direction as the axis of the cutter drum 41 and has substantially the same length. It is connected to the hollow part 63 (FIG. 8). The discharge metal 63 is a bracket 6 fixed to both side surfaces of the lower end of the column 40.
It is installed long in the horizontal direction by using 4. Discharge hardware 6
A plurality of downward spouts 65 are provided in a row at the tip of 3, and bentonite muddy water or ground stabilizer is spouted toward the cutter drum 41 through the spouts 65. A plate-shaped gravel crushing reamer 66 is provided on both side surfaces of the discharge metal piece 63 at intervals in the left-right direction in FIG. It is installed in a fixed form.

The ground improvement method for large depths by the ground improvement device having the above-mentioned structure is constructed as follows. In the ground excavation process, a pair of horizontal cutter drums 41, 41 is provided at the tip.
The pillar 40 provided with is vertically suspended by the wire 60 of a crane (not shown) on the ground, and the cutter drum 41
It is performed by rotating the and utilizing its own weight as the digging force. When excavating the ground, through the mud supply device on the ground, through the mud supply pipe, from the spout 65 of the discharge metal 63 to the vicinity of the cutter drum 41, the minimum necessary amount (very small amount) necessary to have a lubricating effect during the excavation of bentonite mud etc. While supplying (penetration discharge) to As the excavation progresses, the pillar 40 is sequentially lowered. In the case of the present embodiment, since the support column 40 is only suspended by the wire 60 of the crane, the vertical accuracy at the time of excavation is adjusted by operating the upper and lower control plates 55 that exert a reaction force on the excavation hole wall. . Therefore, an inclinometer that measures the verticality of the pillar is installed on the pillar, and the measured value is input to the control device on the ground,
It is displayed and recorded in real time on the display.

The gravel contained in the soil excavated by the cutter drum 41 collides with the crushing reamer 66 to be crushed and atomized, and immediately sucked by the piston type mud pump 45 located immediately above and lifted. It is discharged to the upper side of the partition plate 50 through the mud pipe 48. Therefore, the degree of excavation soil clinging to the cutter drum 41 to generate rotation resistance is small, the excavation action of the cutter drum 41 is smooth, and the excavation resistance to the downward direction is small, so that the excavation proceeds reliably. In addition,
When the mud draining action of the excavated soil by the lifting mud pump 45 causes an excessive suction negative pressure on the lower side of the partition plate 50, the adjustment jack 53 is driven to lower the inclination angle of the partition plate 50. Open it and adjust the soil so that the soil flows down (backflows) from the upper side to maintain the pressure balance.

Ground required depth (underground 70-100m)
The excavation process after excavating up to
A ground stabilizer such as cement milk is supplied (pulled out and discharged) from the ground to the vicinity of the above through the spout 65 of the discharged metal 63, and is stirred and mixed with the soil. At this time, the pump 4
5 operates in the reverse direction to return the excavated soil from the upper side to the lower side of the partition plate 50, and the cutter drum 41 uses the excavated soil and the ground stabilizer for stirring and mixing. Therefore, a high-quality improved ground is formed in the excavation hole in the mark where the cutter drum 41 has risen. In this ground improvement device, the lifting resistance is reduced as a reaction of the excavation pump 45 returning the excavated soil from the upper side to the lower side of the partition plate 50, and a smooth pulling-out process can be performed.

[0032]

[Third Embodiment] Next, a ground improvement apparatus and a ground improvement method of the third embodiment shown in FIG. 10 will be described. As is clear from comparison with FIG. 8, the ground improvement device of the present embodiment has most of the basic configuration in common with the second embodiment. The feature of the embodiment of FIG. 10 is that the screw conveyor 70 is replaced with a screw-type lift pump 72 that is rotated by a hydraulic motor 71 as the lift pump. This is because the pumping distance is as small as about 10 m. The screw type mud pump 72 has a suction port 7 at the bottom of the cylinder.
Equipped with 3. Further, the cylinder is raised above the height of the discharge port 74, and the screw conveyor 7 is attached to the upper end of the cylinder.
A hydraulic motor 71 that rotates 0 is installed. The plurality of screw conveyors 72 are supported at the upper, middle, and lower parts by a horizontal beam 75 that also serves to maintain the intervals. The discharge port 74 is of course opened at a position above the partition plate.

Therefore, the ground improvement method for large depths using the ground improvement device of the above construction is the same as the ground improvement method of the second embodiment except for the function of the pump for pumping mud.
Detailed description is omitted.

[0034]

EFFECTS OF THE INVENTION According to the ground improvement method and the ground improvement apparatus for large depths of the present invention, a cutter drum with a horizontal axis sharply and efficiently cuts (excavates) hard ground or soft rock having an N value of 50 or more. Therefore, it is possible to easily perform deep ground improvement with complicated geological structure. Further, since the cutter drum can reliably cut the connection surface with the already improved ground, the continuity (integration) of the improved ground can be easily ensured.

In the present invention, the earth and sand excavated by the cutter drum is immediately discharged to the ground or considerably above by the mud pump, and the excavated soil is entangled at least around the cutter drum to cause a resistance factor of the rotating torque. The inconvenience that the pressure of the excavation face increases and the resistance of excavation and excavation increases is solved, and it becomes possible to easily improve the ground at a large depth. Since the gravel can be removed by using the action of discharging with a pump for sludge, homogeneous and high-quality ground improvement can be performed.

[Brief description of drawings]

FIG. 1 is an elevational view showing a ground excavation process of a first embodiment.

FIG. 2 is an elevational view showing a drawing process of the first embodiment.

FIG. 3 is a side view showing a main part of the ground improvement device.

FIG. 4 is a front view showing a main part of the ground improvement device.

FIG. 5 is a plan view of a column.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a front view showing a ground improvement device of a second embodiment.

FIG. 8 is a side view showing the ground improvement device of the second embodiment.

9 is a BB arrow line of view of FIG. 7. FIG.

FIG. 10 is a side view showing a ground improvement device of a third embodiment.

[Explanation of symbols]

 1 Cutter Drum 41 Cutter Drum 7 Stirring Blade 2 2 Struts 40 Struts 14 Mud Supply Pipes 15 Bentonite Mud Plant 10 Lifting Mud Pumps 45 Lifting Mud Pumps 11 Lifting Mud Pipes 48 Lifting Mud Pipes 12a Mud Pumps 50 Partition Plates 16 Cement Milk plant 62 Gravel collection basket 17 Strut gripping device 53 Adjustment jack 72 Screw type mud pump

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshio Suzuki, 5-5 Otsuka, Inzai-cho, Inba-gun, Chiba Prefecture Takenaka Corporation Technical Research Institute (72) Inventor Satoshi Saito 1-chome, Otsuka, Inzai-cho, Chiba Prefecture Stock Company Takenaka Corporation Technical Research Institute (72) Inventor Yoshikazu Hojo 8-21-1, Ginza, Chuo-ku, Tokyo Stock Company Takenaka Civil Engineering (72) Inventor Akio Shiina 8--21, Ginza, Chuo-ku, Tokyo No. 1 Takenaka Civil Engineering Co., Ltd. (72) Inventor Ryosuke Okumura 8-21-1, Ginza, Chuo-ku, Tokyo Incorporated Takenaka Civil Engineering

Claims (9)

[Claims] 1. A ground improvement method in which ground is excavated and a ground stabilizer is poured into in-situ excavated soil and agitated and mixed to stabilize the ground, and a cutter drum with at least a pair of horizontal axes is provided at the tip of the ground improvement method. A pillar equipped with a horizontal stirring shaft drum is hung vertically from the ground, and bentonite mud supplied from the mud supply device on the ground is supplied to the vicinity of the cutter through the mud supply pipe while excavating the ground with the cutter drum. Performing and lowering the pillar according to the progress of excavation, installing a lift mud pump at a position directly above where the pair of cutter drums scrapes the excavated soil, and the excavated soil is separated from the ground gravel through the mud pipe by the lift mud pump. Discharge to the equipment, remove the gravel from the excavated soil in the gravel separator, and return the remaining mud to the upper part of the drill hole again by the mud pump. After completing the excavation process to the specified depth, the stirring blade drum is rotated, and the ground stabilization material is supplied from the ground stabilization material supply device through the stabilization material supply pipe to the vicinity of the stirring blade drum to supply the mud in the drill hole. A ground improvement method for large depths, which is characterized by stirring and mixing with and pulling up the columns one after another. 2. A ground improvement method for excavating the ground, pouring the ground stabilizer into the in-situ excavated soil, and stirring and mixing to stabilize it. In the ground improvement method, a pillar provided with a cutter drum having at least a pair of horizontal axes at the tip is provided. Hanging vertically from the ground, excavating the ground with a cutter drum while supplying bentonite muddy water etc. supplied from the muddy water supply device on the ground through the mud supply pipe to the vicinity of the cutter, and lowering the pillars according to the progress of the excavation, The pair of cutter drums installs a mud pump at a position directly above which the excavated soil is scraped up, and the excavated soil is discharged to the upper side of the partition plate through the mud pipe by the mud pump. After completion, the excavated mud is returned from the upper side of the partition plate to the part of the cutter drum by the reverse operation of the lifting mud pump, and further through the stabilizer supply pipe. A ground improvement method for large depths, which is characterized by supplying ground stabilizer from the ground stabilizer supply device to the vicinity of the cutter drum, stirring and mixing with mud soil by the cutter drum, and lifting up the columns one by one. . 3. The partition plate according to claim 2 is partitioned into the shape of an umbrella that traverses the inside of the excavation hole, and the inclination angle thereof is adjusted to flow the excavated mud filled in the excavation hole from above to below. The ground improvement method for large depths is characterized by maintaining the pressure balance between the upper and lower parts by adjusting the. 4. A ground improvement method for large depths, characterized in that a gravel collecting basket is provided near the upper end opening of the lift mud pipe according to claim 2 to remove large-diameter gravel from excavated soil. . 5. A ground improvement device for excavating the ground, injecting a ground stabilizer into the excavated soil in the original position, stirring and mixing the same for stabilization, and at least at the tip of a pillar vertically suspended from the ground. A cutter drum with a pair of horizontal axes is provided, and a stirring blade drum with a horizontal axis is provided at a position slightly above it.
The mud supply pipe connected to the above-ground muddy water supply device is connected to the spout for supplying bentonite muddy water from the vicinity of the cutter drum, and the stabilizer feed pipe connected to the above-ground stabilizer supply device is near the stirring blade drum. It is connected to a pouring outlet that supplies a ground stabilizer to, the columns are sequentially added according to the progress of the excavation of the ground, the pair of cutter drums is installed a pouring pump at a position directly above to scrape the excavated soil, This lift mud pump is connected to the above-mentioned gravel separator through a lift pipe, and the gravel separator that removes gravel from excavated soil is a mud pump that returns mud other than gravel to the upper part of the excavation hole again. It has a mud pipe connected to the pump, the stirring blade drum is rotated in the extraction process after excavation to a predetermined depth, and the stabilizer feed pipe is passed near the stirring blade drum. While supplying the ground stabilizer from the stabilizer on the ground, stirring and mixing with the mud in the excavation hole are performed, the support pillars are sequentially pulled up, and the lifted support pillars are sequentially separated. Horizontal cutter type ground improvement device for depth. 6. The apparatus for gripping a pillar according to claim 5 is installed at an upper end mouth portion of an excavation hole, and the upper end of the pillar is hung by a crane or the like on the ground, which corresponds to a large depth. Horizontal cutter type ground improvement device. 7. A ground improvement device for excavating the ground, pouring the ground stabilizer into the excavated soil at the in-situ, stirring and mixing, and stabilizing the ground stabilizer at least at the tip of a pillar vertically suspended from the ground. It is equipped with a cutter drum with a pair of horizontal shafts, and the mud supply pipe connected to the muddy water supply device on the ground is connected to a spout that supplies bentonite muddy water etc. from the vicinity of the cutter drum, and excavation of the ground by the cutter drum. The pillar is lowered according to the progress of the above, a mud pump is installed at a position directly above which the pair of cutter drums scrapes excavated soil, and the mud pump is connected to the upper side of the partition plate through the mud pipe. The partition plate that cuts across the inside of the excavation hole has one end that can be tilted vertically with respect to the column, and the other end that is supported by the adjustment jack. The stabilizer feed pipe connected to the stabilizer on the ground is connected to the spout for supplying the ground stabilizer to the vicinity of the cutter drum, and the ground stabilizer is used in the extraction process after excavating to a predetermined depth. The horizontal cutter-type ground improvement device for large depths, which is characterized by stirring and mixing with mud soil by a cutter drum while feeding, and lifting up the columns one after another. 8. A horizontal cutter-type ground improvement device for large depths, wherein the sludge pump according to claim 5 or 7 is a piston type pump. 9. A horizontal cutter-type ground improvement device for large depths, characterized in that the mud pump described in claim 7 is a screw-type mud pump.