JPH09317373A - Method of shaft construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reinforce the periphery of the planning region of a shaft and a ground in the planning region precedently by utilizing a method of high-pressure injection agitation construction. SOLUTION: Improvement bodies 5 containing core materials 6 are arrayed to a ground 4 in the periphery of the planning region A of a shaft so as to be mutually lapped and a continuous wall 1 is prepared, and grout injection by an injection rod is executed intermittently into the ground 4 in the planning region A in the planning region A in the vertical direction and improvement bodies 8, 9 are formed. These improvement bodies 8, 9 are arranged so as to be mutually lapped and an improved batholith 2 and an improved intermediate ground 3 are prepared, the improved intermediate ground 3 is used as a precedent ground beam, the ground from a ground surface to the improved intermediate ground 3 is dug down first, the improved intermediate ground 3 is hollowed out, and the lower-side ground of the improved intermediate ground 3 is dug down up to the improved bathlith 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical shaft construction method utilizing a high-pressure jet agitation method, which is one of the ground improvement methods.

[0002]

2. Description of the Related Art Vertical shafts are the starting and reaching bases for shield work, foundations for piers, underground energy storage tanks, underground water tanks,
It has various uses such as an underground parking lot, and its construction has been actively performed in recent years. By the way, if the target ground for constructing the shaft consists of highly collapsible gravel layer and boulder layer and the groundwater level is high, special measures against earth pressure and water pressure are required. Therefore, when such a ground is targeted, the ground around the planned area of the shaft and the lower area of the planned bottom are improved in advance, and the support work is carried out every time when the shaft is dug slightly (about 3 m) ( Uplifting, cutting, etc. are performed to prevent the eruption and collapse of earth and sand and the inflow of groundwater.

For the above-mentioned ground improvement, the high-pressure jet agitation method is used because it is hardly affected by the soil quality, a wide range of ground can be improved by one-time construction, and the adhesion between the improved bodies is excellent. Are becoming more and more popular. This high-pressure jet agitation method, while rotating the injection rod in the ground, from the injection nozzle at the tip of the grout (ground improvement agent) in the direction perpendicular to the injection rod,
Alternatively, it is a method of mixing with water or air and injecting it at high pressure to stir and mix the grout and the surrounding earth and sand to form a columnar improved body.By repeating this construction so that the improved body wraps with each other, The above-mentioned continuous wall or bottom plate can be formed (see, for example, Japanese Patent Publication No. 50-14803 and Japanese Patent Publication No. 51-8493).

[0004]

However, the improved body formed by the above-mentioned high-pressure injection stirring method has the property of being extremely strong against compression but weak against tension. Even if a continuous wall is constructed around the planned area, the resistance to earth pressure is insufficient, and the support work must be carried out every time a little digging, so the extension of construction period and increase of construction cost cannot be avoided. was there.

The present invention has been made in view of the above-mentioned problems of the prior art, and its problem is to reinforce a continuous wall formed around a planned area of a vertical shaft by effectively utilizing a high-pressure injection stirring method. In addition to aiming for
This is to reduce the number of supporting work drastically so that a vertical shaft can be constructed with high efficiency.

[0006]

In order to solve the above-mentioned problems, the present invention provides a construction in which a core material is embedded in a columnar improved body formed by improving the ground by a high-pressure injection stirring method to form a composite body. To form a continuous wall by repeating the plan line, and then repeatedly forming the improved body by the high-pressure jet agitation method in the continuous wall, and the area below the planned bottom of the shaft and its planned depth. The improved bottom plate and the improved intermediate plate are formed in the respective intermediate regions, and thereafter, the ground in the continuous wall is dug down from the surface to the improved intermediate plate, and the improved intermediate plate is hollowed out, and the lower ground is the improved bottom plate. It is characterized by having been dug down to.

A method of forming a composite body by embedding a core material in an improved body formed by a high-pressure jet agitation method has already been disclosed in Japanese Patent Laid-Open No. Hei 3
The invention of the present application is disclosed in JP-A-208936.
This method is used to create a continuous wall. Then, in the continuous wall thus formed, the core material embedded in each improved body strongly resists the tensile force, and the rigidity as a whole becomes extremely high. In addition, by constructing an improved intermediate plate in the intermediate area of the planned depth of the vertical shaft by the high-pressure jet agitation method, this improved intermediate plate is used as a leading underground beam,
The continuous wall with high rigidity described above is supported from the inside, and the ground around the planned area of the shaft becomes more stable.

In the present invention, it is preferable that the continuous wall is formed in a cylindrical shape.
The structure is advantageous for water pressure.

According to the present invention, the improved body forming the improved bottom plate and the improved intermediate plate may be formed by one rotation movement of the injection rod. In this case, it is desirable that the injection rod be extended through the conduit so that excess slime generated during ground improvement is discharged to the ground through the conduit.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 3 show an intermediate stage of shaft construction. In these figures, 1 is a cylindrical continuous wall formed around the planned area A of the shaft, 2 is a disk-shaped improved bottom plate formed in the area B below the planned bottom of the shaft, and 3 is the planned depth of the shaft. These are disc-shaped improved intermediate disks created in the intermediate area C of each, and each of them is prior to excavation in the planned area A of the shaft,
It is formed by improving the ground in a predetermined area in the ground 4 by a high-pressure injection stirring method described later. Continuous wall 1
As shown in FIG. 3, a composite body 7 in which a core material 6 is embedded in a cylindrical improved body 5 formed by a high-pressure injection stirring method is arranged in a circle so that the improved body 5 wraps with each other. It has sufficient water-stopping property and high strength (rigidity). Further, the improved bottom plate 2 and the improved intermediate plate 3 are formed by vertically and horizontally arranging cylindrical improved bodies 8 and 9 which are also formed by the high-pressure jet agitation method so as to wrap each other, and have a sufficient waterproofness and a large strength. have.

In constructing the shaft, first, the continuous wall 1 is formed, then the improved bottom plate 2 and the improved intermediate plate 3 are simultaneously formed, and thereafter, the ground 4 in the continuous wall 1 is dug down in order from the ground surface. . And an appropriate depth (1 to 1 as an example)
2m), the concrete wall 10 having a predetermined thickness is formed by spraying concrete on the inner surface (standing wall) of the continuous wall 1 which is exposed by the excavation, and is further formed on the concrete wall 10, for example, H-shaped. Support ring 11 made of steel
To build. After that, the concrete wall 10 is formed by digging down to the improved intermediate board 3 at once and spraying concrete on the exposed standing wall. At this time, the core material 6 embedded in each improvement body 5 constituting the continuous wall 1 strongly resists the tensile force, and the improved intermediate plate 3 provided in the intermediate region serves as the preceding underground beam to form the continuous wall. Even if 1 is supported from the inside and the inside of the continuous wall 1 is deeply dug at a time, the surrounding sediment will not collapse. Incidentally, the depth to be dug at one time is about 3 m in the case of the conventional construction method in which the core material 6 is not included in the continuous wall and the improved intermediate plate 3 is not provided, while according to the present construction method, It becomes 2 to 3 times (6 to 9 m), and the work efficiency can be improved accordingly.

Thereafter, the improved intermediate board 3 is, for example, shown in FIG.
It is hollowed out in a circular shape along the cutting line indicated by arrow E, leaving its peripheral edge as a support ring 3a, and the lower part thereof is dug down to the improved bottom plate 2. At this time, the continuous wall 1 has the support ring 3a and the improved bottom plate 2 which are the rest of the improved intermediate plate 3.
Since it is supported by and, even if you dig deep between the two at once, the surrounding sediment will not collapse. Then, after this digging, concrete is sprayed on the exposed standing wall to form a concrete wall 10 similar to the above. It should be noted that the improved intermediate board 3 may be formed in plural at predetermined intervals when the vertical shaft to be built is deep. In addition, when concrete is sprayed, a wire mesh 12 (FIG. 2) may be interposed between the wall and the standing wall.

The construction method for forming the continuous wall 1 will be described below. When constructing the continuous wall 1, a self-propelled improvement machine 20 as shown in FIG.
Two rotary units 22 and 23 mounted so that they can be linked to
The steel pipe 24 serving as the core material 6 and the injection rod 25 are supported by. At this time, both are positioned so that the injection nozzle 26 at the tip of the injection rod 25 inserted into the steel pipe 24 projects from the tip of the steel pipe 24, and the rotary unit 22 on the front side in the driving direction is positioned.
The rear end of the steel pipe 24 to the rotary unit 2 on the rear side in the driving direction.
The rear ends of the injection rods 25 are supported by the respective 3's. Further, swivels 27 and 28 are attached to the rear ends of the steel pipe 24 and the injection rod 25, respectively, and a sludge drain hose 29 is extended from the swivel 27 attached to the steel pipe 24 to a mud storage area (not shown). Swivel 28 attached to 25
A grout hose 30 extending from a grout pump (not shown) is connected to each. When air is simultaneously jetted from the jet nozzle 26, the injection rod 25 has a double pipe structure, and the swivel 28 is provided with grout and air injection ports independently. Further, the cutter 31 may be provided at the tip of the injection nozzle 26. Further, a guide 32 for guiding the steel pipe 24 is usually provided on the tip end side of the leader 21.

After the above preparation is completed, the arm 2 of the improved machine 20
The leader 21 is erected vertically on the ground 4 by the operation of 0a, and the steel pipe 24 and the injection rod 25 are driven in the opposite directions by the operation of the rotating units 22 and 23, and are integrally driven into the ground 4. Then, as shown in FIG. 5, when the tip of the injection rod 25 penetrates a predetermined distance from the ground surface,
Grout (eg cement milk) is pumped into the injection rod 25 through the grout hose 30 and swivel 28. Then, the grout is jetted as a jet flow in a direction perpendicular to the pouring rod 25 from the jet nozzle 26 at the tip of the pouring rod 25, and the earth and sand around the pouring rod 25 is mixed with the grout by stirring. By this stirring and mixing, a cylindrical mixing layer 33 is formed around the injection rod 25,
The mixed layer 33 gradually expands downward in accordance with the penetration of the injection rod 25, and the steel pipe 24 moves with the mixed layer 33.
Penetrate inside. During this time, the excess slime generated in the ground 4 by the grout injection flows upward through the gap between the steel pipe 24 and the injection rod 25, and is discharged to the unillustrated waste mud through the swivel 27 and the mud hose 29. In this way, surplus slime is discharged to the ground from the place where it penetrates from the ground by a predetermined distance through the injection of grout and through the gap between the steel pipe 24 and the injection rod 25, so that the earth and sand will not be sprayed to the surface during the ground improvement. .

When the injection rod 25 and the steel pipe 24 are penetrated to a predetermined depth, the injection rod 2 is left with the steel pipe 24 left.
Raise only 5. The mixed layer 33 gradually solidifies to become the improved body 5, and the steel pipe 2 as the core material 6 is provided in the improved body 5.
One complex 7 (FIG. 1) with 4 embedded is formed. Therefore, the continuous wall 1 described above is completed by repeating the formation of the composite body 7 along the planned line L (FIG. 2) of the vertical shaft so that the improvement bodies 5 wrap each other.

In the present embodiment, the improved bottom plate 2 and the improved intermediate plate 3 are also constructed using the improved machine 20. In this case, with the injection of the grout from the injection nozzle 26 first stopped, the injection rod 25 and the steel pipe 2
4 and 4 penetrate into the lower area B of the planned bottom of the shaft,
When the injection nozzle 26 reaches the lowermost position of, the grout is supplied to the injection rod 25 and the injection of the grout from the injection nozzle 26 is started. Then, the injection rod 25 and the steel pipe 24 are integrally raised at a constant speed, and the injection nozzle 26
Reaches the uppermost position of the lower region B, the injection rod 2
The supply of grout to No. 5 is cut off, and the injection of grout from the injection nozzle 26 is stopped. As a result, in the lower area B of the planned bottom of the shaft, a cylindrical improvement body 8 of a predetermined length (Fig. 1)
Is formed. The ascent of the injection rod 25 and the steel pipe 24 is continued, and when the injection nozzle 26 reaches the lowermost position of the intermediate region C, the injection of grout from the injection nozzle 26 is restarted, and the injection nozzle 26 returns to the intermediate region C. The grout injection is stopped when it reaches the top position of. As a result, in the intermediate area C of the vertical shaft, a cylindrical improvement body 9 of a predetermined length (Fig. 1)
Is formed.

The injection rod 25 and the steel pipe 24 are pulled up to the ground as they are, and then the improved machine 20 is operated so that the improved bodies 8 and 9 wrap each other.
The penetration position is changed, and the above-described construction is repeated to connect new improved bodies 8 and 9 one after another, whereby the improved bottom plate 2 and the improved intermediate plate 3 are efficiently formed at the same time.
Then, when forming the improved bodies 8 and 9, the surplus slime is discharged to the ground through the gap between the steel pipe 24 and the injection rod 25, so that the earth and sand are not spouted to the ground surface during the ground improvement. Therefore, the steel pipe 24 used here functions not as a core material but as a conduit for discharging excess slime.

In constructing the continuous wall 1, for example, a construction method as shown in FIG. 6 can be adopted. In this method, a steel pipe 36 provided with a plurality of check valves 35 as a core material 6 is prepared, and a drilling rod 38 having an eccentric expansion bit 37 at its tip is first inserted into the steel pipe 36 as shown in FIG. Then, the eccentric expansion bit 37 is rotated integrally with the drilling rod 38 to excavate the ground 4 and sink the steel pipe 36. Then, when the steel pipe 36 sinks to a predetermined depth, the drilling rod 38 is pulled out from the steel pipe 36, and the injector 39 is inserted as shown in FIG. The injector 39 includes a pair of upper and lower expandable bodies (made of rubber) 39a that can be expanded and contracted, and the pair of expanded bodies 39a is expanded and deformed by a driving means (not shown) to arbitrarily change the inside of the steel pipe 36. Fixed in position. The grout is pressure-fed to the pouring machine 39 through a pouring tube 40 extending from the ground, and the grout is a hermetic seal formed between the pair of swelling bodies 39a and the inner surface of the steel pipe 36. It is supplied to the pressure chamber 41.

After inserting the injection machine 39 to the tip of the steel pipe 36, the injection machine 39 is pulled up at a predetermined pitch, and as shown in FIGS. 6 to 6, a pair of bulging bodies 39a is expanded at each pulling position. It is deformed to form a pressure chamber 41, and grout is supplied to the pressure chamber 41 through an injection pipe 40. Then, the check valve 35 provided in the steel pipe 36 is opened at each position, the grout is injected around the steel pipe 36 to form the mixed layer 42, and the mixed layer 42 sequentially expands from the lower side to the upper side, This mixed layer 42 is solidified to improve the above-mentioned improved body 5
(FIGS. 1 to 3). Therefore, by leaving the steel pipe 36 as the core material 6 in the improved body 5, the composite body 7 (FIGS. 1 to 3) described above is formed.

The continuous wall formed along the planned line L of the vertical shaft may be a continuous wall 45 having a double structure as shown in FIG. In this case, the inner wall body 46 is composed of the composite body 49 in which the core material 48 is embedded in the improvement body 47 as in the above-described embodiment, and the composite body 49 is arranged in contact with each other, while the outer wall body is arranged. Reference numeral 50 denotes a columnar improvement body 51 containing no core material, and the improvement body 51 is arranged so as to be located between the composite bodies 49 of the inner wall body 46 and in contact with the composite body 49. can do.

Further, the continuous walls 1 or 45 described above are arranged so as to slightly wrap the composite 7 (), or arranged so as to be slightly separated (), as shown in FIG. Improved columns 52 formed separately from each other
Alternatively, the inner side wall body 46 and the outer side wall body 50 may be reinforced by the improved columns 52 which are also separately formed ().

When the vertical shaft is used as a starting and reaching base for shield construction, in order to facilitate the opening with the excavation tunnel, the core materials 6 and 48 of the composites 7 and 49 corresponding to the opening are It is desirable to form it from a material having good destructibility such as plastic.

[0024]

As described above in detail, according to the vertical shaft construction method of the present invention, the continuous wall formed by ground improvement around the planned area of the vertical shaft includes the piles and the vertical shaft is planned. Since an improved intermediate ground that functions as a leading beam is provided in the ground in the area by improving the ground, the ground around the planned area is remarkably stable, the depth that can be dug at one time becomes large, and the number of support operations is significant. It is possible to reduce the construction period and the construction cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an intermediate stage of construction of a vertical shaft according to the present invention.

FIG. 2 is a plan view of the shaft shown in FIG. 1 viewed from above.

FIG. 3 is a perspective view showing a structure of a continuous wall.

FIG. 4 is a side view showing an improved machine for performing the high-pressure jet agitation method and its usage.

FIG. 5 is a schematic diagram showing a process of forming an improved body by a high-pressure jet agitation method.

FIG. 6 is a schematic diagram showing another forming process of the improved body by the high-pressure injection stirring method.

FIG. 7 is a plan view schematically showing another form of the continuous wall.

FIG. 8 is a plan view schematically showing still another aspect of the continuous wall.

[Explanation of symbols]

 1 continuous wall 2 improved bottom plate 3 improved intermediate plate 4 ground 5 improved body 6 core material 7 complex 8 and 9 improved body 20 improved machine 24 steel pipe (core material) 25 injection rod 26 injection nozzle 35 check valve 36 steel pipe (core material) ) 37 Eccentric extension bit 38 Drilling rod 41 Injector A Vertical planned area of vertical shaft B Lower area of vertical shaft C Intermediate area of vertical shaft L Vertical shaft planned line

Claims (4)

[Claims] 1. A continuous wall is constructed by repeatedly constructing a composite body by embedding a core material in a columnar improved body formed by improving the ground by a high-pressure jet agitation method, along a planned line of a shaft, Next, the formation of an improved body by a high-pressure jet agitation method is repeatedly performed in the continuous wall to form an improved bottom plate and an improved intermediate plate in the lower area of the planned bottom of the shaft and the intermediate area of the planned depth, respectively. Thereafter, the ground in the continuous wall is dug down from the ground surface to the improved intermediate ground, and the improved intermediate ground is hollowed out, and the lower ground is dug down to the improved bottom ground. 2. The shaft construction method according to claim 1, wherein the continuous wall is formed into a cylindrical shape. 3. The shaft construction method according to claim 1, wherein the improved bodies constituting the improved bottom plate and the improved intermediate plate are formed by a single rotational movement of the injection rod. 4. The shaft construction method according to claim 3, wherein the injection rod is extended through a conduit, and excess slime generated during ground improvement is discharged to the ground through the conduit.