JP2000170155A - Partial improving method for shallow layer in soft ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a partial improving method for a shallow layer in a soft ground which can be smoothly improved in order to efficiently lay various kinds of embedding pipes. SOLUTION: A small diameter agitating blade 18 for excavating and agitating a ditch is provided at the upper part of a hollow rotary shaft 20 and a large diameter agitating blade 19 for excavating and agitating a hole is provided at the lower part thereof. A hollow rotary shaft 20 of a ground excavating and agitating device 17 in which a delivery hole discharging a solidifying liquid in the excavated and agitated soil agitated by the agitator is formed in the shaft 20 is fitted vertically or obliquely to a rotary drive device so as to be horizontally transferable through a thrusting device 16, in the traveling device 10 transferable on the ground. The hollow rotary shaft 20 is inserted to penetrate the ground and rotated and further horizontally transferred while discharging the solidifying liquid supplied through the hollow part of the rotary shaft 20 from the delivery pipe 37 while agitating the underground to partially improve the shallow layer of the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a partial improvement method for selectively improving and solidifying a shallow part of soft ground,
For example, the present invention relates to a method for solidifying and improving the soft ground in order to efficiently lay a buried pipe such as a gas pipe or a water pipe in the soft ground by excavating the improved hardened ground.

[0002]

2. Description of the Related Art Conventionally, as a method of improving and solidifying a shallow portion of a soft ground of this type, a vertical mixing and stirring blade is vertically moved while rotating in the depth direction, and a solidified material is ejected into the ground. There is a method of mixing and stirring with earth and sand. In this method, as shown in FIG. 8, the apparatus is set on a predetermined portion of the soft ground 1, and the stirring blade 3 provided on the rotating shaft 2 is rotated and moved up and down from the stirring blade 3 through a nozzle. A predetermined solidified material is jetted into the ground 1 to form a columnar body 4, which is connected in the horizontal direction.

However, in this method, after the earth and sand and the solidified material are mixed and stirred in the depth direction, the operation of lifting the stirring blade 3 to the ground and horizontally moving is repeated, so that the columnar bodies solidified in the horizontal direction are connected. It takes time to form the partially improved ground in the shallow part. On the other hand, Japanese Patent Application Laid-Open No. Hei 7-300853 discloses a method of horizontally moving a stirring blade while moving it up and down. In this method, the soil moves up and down zigzag with a small stroke between the injection nozzles, and is moved forward and backward by a traveling device to stir and mix the soil as a solidifying material. However, in this method, the mechanism and operation for synchronizing the vertical movement and the horizontal movement are complicated.

On the other hand, there is a method in which a solidified material is sprayed on the surface of the ground and mixed and stirred with the ground by a stirring blade. This method
As shown in FIG. 9, a solidifying material is sprayed on the surface of the soft ground 1 to a predetermined thickness in advance, the road stabilizer 5 is moved in the direction of the white arrow, and the stirring blade 6 is rotated to lower the surface below the horizontal plane. The excavating and stirring unit 8 is formed by stirring and mixing the solidified material with the soil in a relatively shallow layer having a depth of 1 to 2 m from the surface of the ground 1 by rotation.

[0005] However, in this mixing and stirring method, in order to solidify to a certain depth from the ground surface and to selectively improve / strengthen its surroundings in order to protect the excavation hole 7 for underground pipes, it is necessary to use the necessary soil. The solidification exceeding the amount is performed, which is an inefficient operation in terms of the amount of the solidified material used.

[0006]

As described above, the conventional method for improving and solidifying the shallow part of soft ground has a low working efficiency.
There are problems such as a long working time and a complicated mechanism and operation of the ground improvement solidification device used in this method.

It is an object of the present invention to provide a method of partially improving a shallow portion of a soft ground which has solved the above-mentioned problems.

[0008]

The present invention is configured as follows. The partial improvement method for the shallow portion of the soft ground according to the invention of claim 1 is characterized in that a small-diameter stirring blade for excavating and stirring a groove is provided at an upper portion of a hollow rotary shaft, and a large-diameter stirring blade for stirring and excavating a hole is provided at a lower portion, and The hollow rotary shaft of a ground excavation and stirring device provided with a discharge hole for discharging a liquid solidification material into excavated and stirred earth and sand can be horizontally moved to the frame via a thrust device provided on a frame movable on the ground. The hollow rotary shaft is penetrated into the ground and rotated, and the solidified liquid supplied through the hollow portion of the rotary shaft is stirred while excavating and stirring the underground ground. While discharging the material from the discharge holes, the material is horizontally moved together with the rotary driving device, and the ground in the shallow portion is partially improved. According to a second aspect of the present invention, in the first aspect of the present invention, the ground in the shallow portion to be partially improved is a soft ground zone surrounding the outer periphery of a pipe to be buried. A circular or rectangular columnar solidified body larger than the groove excavation stirrer excavated by the stirring blade is formed in the hole excavation stirrer excavated and agitated by the large diameter impeller, and the inside of the solidified body is excavated and piped. Form piping holes for body laying.

In the present invention, the stirring bit in each of the small-diameter and large-diameter stirring blades is mounted around a hollow rotary shaft via a blade having a required width, and the stirring width is changed in the depth direction. A columnar solid body having an arbitrary cross section can be formed without vertically moving the hollow rotary shaft.

It is desirable that the stirring bit is arranged such that the projected area in the improved traveling direction is the entire area of the cross section of the solidified body.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. FIG.
Shows a general view, in which the ground 11 of the soft ground 1
Is provided with a traveling device 10. A traveling wheel 13 and a frame lifting / lowering jack 14 are provided before and after the main body frame 12 of the traveling device 10, and in the illustrated example, the frame lifting / lowering jack 14 is extended to lift the main body frame 12 to lift the traveling wheel 13 from the ground, Frame lifting jack 1
Reference numeral 4 denotes a state in which the traveling device 10 is temporarily fixed on the ground. The backhoe 1 is located at the front of the body frame 12.
5 (only a part is shown in the figure) is attached.

A ground excavation and stirring device 17 is provided on the main body frame 12 of the traveling device 10 via a thrust device 16 composed of a hydraulic jack so as to be horizontally movable with respect to the main body frame 12.

To explain further, the ground excavation stirring device 17
Is provided with a hollow rotary shaft 20 provided with a small-diameter stirring blade 18 for groove improvement at the upper part and a large-diameter stirring blade 19 for ground improvement at the lower part, and the hollow rotary shaft 20 is attached to the horizontal movable support member 21. Via a thrust bearing, it is supported vertically or inclined and rotatably by a rotary drive device. The horizontal movable support member 21 is supported by the main frame 12 so as to be horizontally movable by the thrust device 16.

The rotation support mechanism of the hollow rotary shaft 20 will be described with reference to FIG. 2. A thrust bearing 25 is supported by upper and lower support brackets 23 and 24 provided on a side frame 22 of a horizontally movable support member 21. The upper portion of the hollow rotary shaft 20 is rotatably supported by the horizontal movable support member 21 by the bearing 25. A drive gear 26 is axially mounted on the hollow rotary shaft 20, and a drive pinion 29 fixed to a motor shaft 28 of a hydraulic motor 27, which is a rotary drive device, meshes with the drive gear 26. The hydraulic motor 27 is installed on the upper support frame 30 of the horizontal movable support member 21.

The upper part of the hollow rotary shaft 20 rotatably penetrates the upper support frame 30 of the horizontal movable support member 21, and is connected to the upper end of the hollow rotary shaft 20 via a swivel joint 31 on the upper surface of the upper support frame 30. An injection hose 32 of a liquid solidifying material such as cement milk or cement mortar is connected.

Therefore, the hollow rotary shaft 20 is rotated by the hydraulic motor 27, and
And can be horizontally moved back and forth along the main body frame 12 by the thrust device 16.

The ground excavation stirring device 17 comprising the hollow rotary shaft 20, the small-diameter stirring blade 18 provided on the shaft, and the large-diameter stirring blade 19 will be described in detail with reference to FIGS.

As shown in each figure, the hollow rotary shaft 20
A large-diameter stirring blade 19 is provided at the lower end. The large-diameter stirring blade 19 includes a plurality of upper and lower stages, that is, in the illustrated example, an upper-stage large-diameter stirring blade 19a, a middle-stage large-diameter stirring blade 19b, and a lower-stage large-diameter stirring blade 19c. This large diameter impeller 1
When the ground 9 excavates and agitates while horizontally moving while being integrally rotated by the hollow rotary shaft 20, the hole excavation and agitation unit 33 having a columnar shape in the ground and having a circular cross section perpendicular to the longitudinal direction is excavated and agitated. The upper, middle, and lower large-diameter stirring blades 19a, 19b, 19c have different shapes and sizes as shown in the figure.

The large-diameter stirring blade 19a at the upper stage has a stirring bit 35 at the tip of a blade 34 arranged in a plane cross shape so as to excavate and form an arcuate curved surface portion above the hole excavating and stirring section 33 having a circular cross section. The stirring bit 35 is provided upward and downward for each blade 34, and is inclined at a predetermined angle toward the center of rotation.

In order to excavate and agitate the arcuate curved surface portion in the middle of the hole excavating and agitating portion 33 having a circular cross section, the agitating bit 35 at the tip of the blade 34 Each blade 34 is provided so as to rise and fall at a right angle upward and downward.

The lower-stage large-diameter stirring blade 19c excavates and forms an arc-shaped curved surface portion below the hole excavating and stirring section 33 having a circular cross section. It is provided upwardly and downwardly at every 34 and inclined outward at a predetermined angle.

Each of the upper, middle and lower stirring bits 35 is inclined at a predetermined angle θ with respect to the normal of the rotation trajectory of the blade 34, whereby the stirring bits 3
It is provided so that the earth and sand excavated and stirred in 5 can be efficiently excavated while being swept toward the center of rotation. Also,
Large-diameter stirring blades 19a, 19b, 19 in the upper, middle, and lower stages
3C, the solidified material discharge pipe 37 whose base end is connected to a discharge port 36 penetrating the peripheral wall of the hollow rotary shaft 20 is provided on the lower surface of one of the blades 34 extending radially in four directions in each stage. Are attached by welding.

Therefore, when the large-diameter stirring blade 19 rotates integrally with the hollow rotary shaft 20, the large-diameter stirring blades 19a, 19b, and 19c of the upper, middle, and lower stages form the hole excavation and stirring unit 33 having a circular cross section. It is excavated and stirred on the ground. Subsequently, while the hollow rotary shaft 20 is rotated by the hydraulic motor 27 as a drive source, the hollow rotary shaft 20 is supported by the horizontally movable support member 21, and the main body frame 12 of the traveling device 10 is horizontally moved forward by the thrust device 16, so that the ground The columnar hole excavation and stirring unit 33 can be excavated and stirred. At this time, the solidified material such as cement milk supplied from the solidified material supply hose 32 passes through the hollow rotary shaft 20 and is discharged from the discharge pipe 37, and the large diameter stirring blades 19 are discharged by the solidified material.
Is mixed into the excavated and agitated soil in the excavated and agitated portion 33 excavated in the above, and the ground is improved into a columnar shape.

As shown in each figure, a small-diameter stirring blade 18 is provided from the middle to the upper part except for the lower end of the hollow rotary shaft 20 to excavate and agitate the groove excavation and agitating section 38. The small-diameter stirring blades 18 are also provided in a plurality of stages at predetermined intervals in upper and lower stages and at predetermined angular intervals in the upper and lower stages in the circumferential direction of the pipe. Each of the small-diameter stirring blades 18 is configured such that a stirring bit 35 is attached to a tip of a short blade 34 disposed in a cross shape on the hollow rotary shaft 20, for each blade 34, upward or downward.

A discharge hole 39 may be opened through the peripheral wall of the hollow rotary shaft 20 at an appropriate position in the vertical direction within the range in which the small diameter stirring blade 18 is provided. A solidified material such as cement milk is discharged from the discharge hole 39 through the shaft 20, and the solidified material is mixed into the excavated earth and sand in the groove excavation and stirring section 38 excavated and stirred by the small-diameter stirring blade 18, and Improve the ground. When the discharge hole is not opened, only excavation of the groove is performed.

FIGS. 6 and 7 show a second embodiment. In the second embodiment, in order to form a rectangular column-shaped (rectangular cross-section) hole excavating and stirring section 33a in the ground, the large-diameter stirring blades 19 provided at the lower portion of the hollow rotary shaft 20 each have an upper stage, a middle stage, and a lower stage. The lengths of the blades 34 of the diameter stirring blades 19a, 19b, and 19c are set to the same size, which is the same as the upper stage, the middle stage, and the lower stage for forming the cylindrical hole excavation stirring unit 33 in the first embodiment. It is slightly different from each of the large diameter stirring blades 19a, 19b, 19c. Other configurations are the same as the first embodiment.

In the second embodiment, the large-diameter stirring blades 19 and the small-diameter stirring blades 18 are rotated and horizontally moved integrally with the hollow rotary shaft 20, thereby forming a groove excavation / stirring unit 38 and a lower part thereof. It is possible to form a hole excavation and stirring section 33a having a large diameter and a rectangular cross section.

[Operation of Embodiment] The operation of the embodiment of the present invention will be described. In order to lay the main pipe 40 (shown in FIG. 5), on the starting side and the arrival side in the soft ground 1 that needs to be solidified,
A starting shaft and a reaching shaft larger than the outer diameter of the large diameter stirring blade 19 are constructed. Large diameter stirring blade 19 or large and small stirring blades 19, 18
(Only the solidified material supply hose 32 is shown in the figure), and the large and small stirring blades 19,
While rotating 18, the solidified material is mixed into the excavated and stirred earth and sand. At this time, the driving of the thrust device 16 causes the respective stirring blades 19 and 18 to move horizontally while rotating together with the hollow rotary shaft 20. As a result, the excavated agitated soil and the solidified material are mixed and agitated. From the ground surface, the groove excavation / stirring unit 38 excavates or solidifies with the rod width of the hollow rotary shaft 20, and the underground portion solidifies into a shape that expands to a large diameter (that is, a hole excavation / agitation unit 33). ing. When the large and small stirring blades 19 and 18 reach the arrival side vertical hole,
The hollow rotary shaft 20 is pulled out from the upright hole to the ground. After the ground in which the stirred earth and sand and the solidified material are mixed is solidified, the inside of the columnar solidified body 41 is excavated and discharged to form a pipe hole 43 by, for example, a propulsion method, and a sheath pipe inserted into the pipe hole 43 is formed. The main pipe 40 is laid inside 42.

Embodiment An embodiment will be described below. In the embodiment, as shown in FIG. 5, a sheath pipe 42 of φ812.8 mm for main pipe protection is laid with 1.5 m of earth covering on soft ground having an N value of 1 or less, and then a main pipe 40 of φ609.6 mm is laid. did.
Therefore, in the case where it is necessary to excavate and stir the φ920 mm hole excavation / stirring unit 33 to form a cavity for laying the sheath pipe, the size of the solidification target and the strength after solidification were calculated. As a result, the solidification range was 1500 m in diameter as a concentric circle with the hole excavation section.
m should be solidified to a uniaxial compression strength of 3 kgf / cm ² ,
Cement solidifying material at that time, earth and sand 1m ³ per 80kg
It was confirmed by experiments that the amount of f was added.

As shown in the figure, the projected surface shape of the portion of the stirring blade 19 that passes when the tip of the stirring bit 35 rotates is the same as the cross-sectional shape of the solid columnar body. Here, the groove is formed in a circular shape with a diameter of 1500 mm from the above design. If the hole cross section required for design is rectangular, it may be excavated in a rectangular shape using the stirring blade described in the second embodiment.

[0031]

According to the present invention, a hollow rotary shaft having a small diameter stirring blade at the upper part and a large diameter stirring blade at the lower part penetrates into the ground and horizontally moves while rotating to mix the solidified material. Work efficiency is improved. Further, since the area around the underground pipe can be limited and solidified, the amount of soil in the solidified ground can be reduced, and the amount of solidified material used and the amount of construction can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of a first embodiment of an apparatus for performing a method of the present invention.

FIG. 2 is an enlarged plan view of a part of FIG.

FIG. 3 is a side view of the ground excavating and stirring apparatus shown as the first embodiment.

FIG. 4 shows (A), (B), (C), (D), and (E)
It is sectional drawing of AA, BB, CC, DD, and EE of FIG.

FIG. 5 is a cross-sectional view showing a state in which the main pipe and the sheath pipe are buried in the ground that has been improved and solidified by the apparatus of the first embodiment.

FIG. 6 is a side view of a ground excavation stirring device shown as a second embodiment.

7A is a cross-sectional view of a rectangular excavation stirring ground stirred by the apparatus of FIG. 6, and FIG. 7B is a cross-sectional view of FIG.

FIG. 8 is an explanatory diagram of a soft ground improvement method according to a first conventional example.

FIG. 9 is an explanatory diagram of a soft ground improvement method according to a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Soft ground 2 Rotating shaft 3 Stirrer blade 4 Columnar body 5 Road stabilizer 6 Stirrer blade 7 Drilling hole 8 Drilling stirrer 10 Traveling device 11 Ground 12 Main body frame 13 Running wheel 14 Frame lifting jack 15 Backhoe 16 Thrust device 17 Drilling and stirring device 18 Small-diameter stirring blade 19 Large-diameter stirring blade 20 Hollow rotating shaft 21 Horizontal movable support member 22 Side frame 23 Upper support bracket 24 Lower support bracket 25 Thrust bearing 26 Drive gear 27 Hydraulic motor 28 Motor shaft 29 Drive pinion 30 Upper support frame 31 Swivel Joint 32 Injection hose 33 Hole excavation and stirring section 34 Blade 35 Stirring bit 36 Discharge port 37 Discharge pipe 38 Groove excavation and stirring section 39 Discharge hole 40 Main pipe 41 Columnar solidified body 42 Sheath pipe 43 Piping hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Mochizuki 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation (72) Inventor Takuya Saito 2-6-Otemachi, Chiyoda-ku, Tokyo No. 3 New Nippon Steel Corporation F-term (reference) 2D040 AB05 AC05 BA08 BD05 CA01 CB03 DA11 DB07 EA02 EA16 EA18

Claims (2)

[Claims] 1. A small-diameter stirring blade for excavating and stirring a groove is provided at an upper portion of a hollow rotary shaft, and a large-diameter stirring blade for excavating and stirring a hole is provided at a lower portion, and a liquid solidified material is discharged into excavated and stirred earth and sand. Through a thrust device provided on a frame movable on the ground, the hollow rotary shaft of the ground excavation and stirring device provided with a discharge hole is vertically or inclined to a rotary drive device which is horizontally movably supported by the frame. And install
The hollow rotary shaft is penetrated into the ground and rotated, and while excavating and stirring the underground ground, while discharging the liquid solidified material supplied through the hollow portion of the rotary shaft from the discharge hole, the hollow rotary shaft is horizontally rotated together with the rotary driving device. A method of partially improving soft ground shallow layers, which comprises moving and partially improving the ground in shallow layers. 2. The part of the soft ground shallow part according to claim 1, wherein the ground of the shallow part to be partially improved is a soft ground zone surrounding the outer periphery of the pipe to be buried. Improved construction method.