JP2009074309A - Vertical shaft and its construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a large bore vertical shaft even in the soft ground of a city part or the like, to reduce an occupied area of the vertical shaft in the ground part and to reduce a construction period of a diameter enlarged part. <P>SOLUTION: The vertical shaft 1 is constructed by excavating a small bore vertical shaft 10 from the ground part 2, placing a plurality of curved pipe roofs 21 from a lower inner peripheral wall 10a of the small bore vertical shaft 10 toward the radial outside of the small bore vertical shaft 10 over the whole outer periphery so that the tips face downward, excavating the inside of the placed curved pipe roofs 21 to form the diameter enlarged part 20, and excavating under the diameter enlarged part 20 to construct a large bore vertical shaft 30 larger in diameter than the small bore vertical shaft 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shaft and a construction method thereof.

Conventionally, the construction method of a vertical shaft is a shield method using a shield excavator that digs downward in the vertical direction (for example, refer to Patent Document 1), a caisson method for sinking a caisson by its own weight (for example, refer to Patent Document 2), A deep foundation method is generally used.
Patent Document 1 installs a segment while drilling downward in the vertical direction by a full swiveling shaft excavator equipped with a cutter at the tip of a shaft. Patent Document 2 describes a swivelable excavating cutter that excavates the inside of a caisson. Using a shaft excavator equipped with an excavator, the excavation cutter expands the diameter of the lower side of the caisson blade edge so that the caisson sinks under its own weight and a shaft is constructed.

By the way, in recent years, especially in urban areas, for roads, subways, storm water trunks, etc., large diameter cross sections, for example, tunnel outer diameter (outer diameter of shield excavator) exceeding 10 m and shaft depth However, there is an increasing number of cases where deep shield tunnels are adopted. In such a tunnel, a large-diameter shaft having an inner diameter of, for example, 20 to 30 m is constructed as a starting base under the shaft for starting the shield excavator.
Japanese Patent Laid-Open No. 5-171887 JP-A-8-284579

However, the construction of a conventional shaft having a large diameter cross section has the following problems.
In other words, in urban areas, there may be a small occupied area on the ground that can be used as a work yard, and there is a drawback that it is impossible to construct a shaft with a large diameter cross section that requires a large area of land on the ground.
Therefore, there are cases where the ground side of the shaft is a small-diameter shaft having a small-diameter cross section, and a large-diameter shaft having a size capable of constructing a starting base for a shield excavator is provided below a predetermined position in the depth direction. As construction in this case, a small-diameter shaft was excavated in advance, and a large-diameter shaft was constructed by widening excavation below a predetermined position of the small-diameter shaft using NATM. However, in the case of a soft ground such as an urban area, if a large-diameter shaft that exceeds 10 m is constructed by widening a small-diameter shaft using NATM, the natural ground loosens and collapses, resulting in excavation. There was a risk of difficulty, and large-scale ground improvement was required. Therefore, a construction method capable of reliably constructing such a large-diameter shaft has been demanded, and there remains room for improvement in that respect.

The present invention has been made in view of the above-described problems. A large-diameter shaft can be constructed even in soft ground such as an urban area, and the occupation area of the shaft in the ground portion can be reduced. An object is to provide a shaft that can be constructed and a method for constructing the shaft.
Another object of the present invention is to provide a shaft and its construction method capable of shortening the construction period of the enlarged diameter portion.

  In order to achieve the above object, the shaft according to the present invention is a shaft having a small-diameter shaft and a diameter-expanding portion below the shaft, and the diameter-expanding portion is the same as that of the small-diameter shaft over the entire circumference from the small-diameter shaft It is characterized by a structure in which a plurality of curved pipe roofs are driven outward in the radial direction.

  Further, in the shaft construction method according to the present invention, a first step of excavating a small-diameter shaft from the ground part, and a plurality of curves from the small-diameter shaft to the outside in the radial direction of the small-diameter shaft over the entire circumference. It has the 2nd process of placing a pipe roof, and the 3rd process of excavating the inside of the curved pipe roof which was laid, and forming a diameter expansion part.

  In the present invention, a small-diameter shaft is excavated from the ground at a predetermined depth, and a curved pipe roof having a high cross-sectional rigidity is directed from the small-diameter shaft to the outside in the radial direction of the shaft, and a plurality of shafts are driven along the shaft circumferential direction. By providing, the roof part which has the high rigidity in an enlarged diameter part can be constructed | assembled. For this reason, the natural pipe above the enlarged diameter portion can be reliably supported from below by the curved pipe roof, and the looseness of the natural ground can be suppressed even in soft ground such as an urban area. And under the roof part formed by the curved pipe roof, excavation of the space inside the enlarged diameter part, for example, the large diameter shaft provided below the enlarged diameter part can be performed safely. Furthermore, the ratio of the outer diameter of the large-diameter shaft to the outer diameter of the small-diameter shaft can be increased.

Moreover, in the shaft which concerns on this invention, it is preferable that the 1st support ring member is being fixed to the inner peripheral wall of a small diameter shaft along the shaft peripheral direction.
In the present invention, the small-diameter shaft can be reinforced by fixing and supporting the first support ring member on the inner peripheral wall of the small-diameter shaft in the shaft circumferential direction.

Moreover, in the shaft according to the present invention, it is preferable that the second support ring member is fixed to the plurality of curved pipe roofs along the shaft circumferential direction so as to connect the respective leading ends.
In the present invention, the curved pipe roofs can be more firmly connected to each other by fixing the second support ring member to the distal ends of the multiple curved pipe roofs.

Moreover, in the shaft which concerns on this invention, you may have a large diameter shaft which makes a diameter larger than a small diameter shaft below the diameter expansion part.
In the shaft construction method according to the present invention, a large-diameter shaft having a larger diameter than the small-diameter shaft may be excavated below the enlarged diameter portion.
In the present invention, the enlarged-diameter portion is constructed of a roof portion having high rigidity, and supports a natural ground above the enlarged-diameter portion, so that a large-diameter shaft can be provided below the enlarged-diameter portion. The space below the shaft can be used more effectively.

According to the shaft and its construction method of the present invention, since the enlarged diameter portion is constructed using a highly rigid curved pipe roof, it can be expanded without loosening the ground even in soft ground such as an urban area. A diameter portion can be constructed, and a large-diameter shaft having a larger ratio of the outer diameter to the outer diameter of the small-diameter shaft can be provided below the enlarged-diameter portion. Therefore, the outer diameter of the small-diameter shaft can be made smaller than the outer diameter of the large-diameter shaft, so that the occupation area of the shaft required for the ground part is small and the work yard is narrow like in urban areas. Even so, a large-diameter shaft can be constructed under the shaft.
In addition, after constructing the curved pipe roof, it will be excavated inside the space, so it is possible to excavate safely compared to the case where the enlarged diameter part is constructed while repeatedly supporting by the conventional NATM, The construction period can be shortened.

Hereinafter, a shaft and its construction method according to an embodiment of the present invention will be described with reference to FIGS.
1 is a partially broken perspective view showing the overall structure of a shaft according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the shaft shown in FIG. 1, and FIGS. 3 (a) to 3 (c) are steps for constructing the shaft. FIG. 4 is a diagram showing an outline of a shaft excavator.

As shown in FIG. 1, a vertical shaft 1 according to the present embodiment is employed for constructing a shield tunnel used in, for example, a road or a subway in an urban area, and advances a shield excavator (not shown). It is a shaft for. That is, the large-diameter shaft 30 having an outer diameter of, for example, 20 to 30 m is formed below the shaft 1.
In the present embodiment, the target geology for constructing the shaft 1 is a natural ground that can be excavated by NATM, and is, for example, a natural ground having deformation, strength, and water permeability characteristics of a consolidated silt. .

First, the structure of the shaft 1 will be described based on the drawings.
As shown in FIGS. 1 and 2, the shaft 1 has a small-diameter shaft 10, an enlarged-diameter portion 20, and a large-diameter shaft 30 arranged in this order downward from the ground portion, and each has a circular cross section. There is no.

  The small-diameter shaft 10 has an outer diameter of a shaft section of about 10 m, for example, and is constructed to a predetermined depth using a shaft excavator 40 shown in FIG. That is, on the wall surface of the small-diameter shaft 10, a cylindrical body 11 such as a steel or concrete segment is constructed along the excavated pit wall. That is, the cylindrical body 11 is in a state where the well wall of the small section vertical shaft portion 10 is supported.

  The enlarged diameter portion 20 is driven from the lower inner peripheral wall 10a of the small-diameter shaft 10 toward the radially outer side of the small-diameter shaft 10 over the entire outer circumference at a predetermined pitch along the shaft circumferential direction. .., A first support ring member 22 (first support member) provided in the vicinity of the mounting portion 21a of the curved pipe roof 21 along the shaft circumferential direction, and a plurality of the curved pipe roofs 21, 21,. The second support ring member 24 (second support member) is provided so as to be connected to the tip end portion 21b of the curved pipe roofs 21, 21,. In FIG. 1, the first support ring member 22 and the second support ring member 24 are omitted.

  The curved pipe roof 21 is a hollow steel pipe having a high cross-sectional rigidity curved with a predetermined curvature in the axial direction. As the outer diameter of the curved pipe roof 21, for example, when the outer diameter of the large-diameter shaft 30 is 20 to 30 m, one having a diameter of 600 to 800 mm can be adopted. The plurality of curved pipe roofs 21, 21,... Are arranged so as to be substantially radially downward in the radial direction of the shaft, and are constructed so that the tip 21 b is positioned below the attachment 21 a as shown in the figure. .

And the blowing part 23 (refer FIG. 1) is constructed between the curved pipe roofs 21 and 21 adjacent in a horizontal direction. As described above, the enlarged diameter portion 20 formed by the curved pipe roofs 21, 21,... And the blowing portion 23 has an arch shape in a side view and forms a portion corresponding to the roof of the large-diameter shaft 30. be able to.
Such curved pipe roofs 21, 21,... Are constructed using a press-fitting device such as an earth auger, which will be described in detail later.

  The first support ring member 22 shown in FIG. 2 is provided in a ring shape along the circumferential direction of the small-diameter shaft 10, supports the small-diameter shaft 10, and welding means or the like on the attachment portion 21a of each curved pipe roof 21 It is fixed by.

Moreover, the 2nd support ring member 24 is being fixed to the front-end | tip part 21b of the some curve pipe roof 21 with a welding means etc. as mentioned above. Thereby, it becomes the structure where curve pipe roofs 21 and 21 were connected more firmly.
These first and second support ring members 22 and 24 may be made of steel or reinforced concrete.

  The large-diameter shaft 30 is constructed by a well-known NATM, and is constructed of sprayed concrete 31 and rock bolts 32.

Next, the construction procedure of the shaft 1 constructed as described above will be described with reference to FIGS.
As shown to Fig.3 (a), the process which constructs | assembles the small diameter shaft 10 from the ground part 2 to the enlarged diameter part 20 first is performed (1st process). Specifically, in this embodiment, construction is performed using a shaft excavator 40 shown in FIG. For the shaft excavator 40, for example, a ground excavator disclosed in JP-A-2005-30198 can be used.

  As shown in FIG. 4, the shaft excavator 40 is a device that excavates the ground in the vertical direction, and includes an excavation mechanism 41, a holding mechanism 42, and a drive mechanism 43. Specifically, the excavation mechanism 41 includes an excavation blade 41 b at the lower end portion of a casing 41 a that is disposed substantially coaxially with the central axis of the shaft 1. The drive mechanism 43 rotates the excavating blade 41b with the casing 41a as a rotation axis to excavate the ground, and excavated sediment generated by excavation is discharged to the ground through the casing 41a using an appropriate soil removal method, for example, a bucket. To do. The holding mechanism 42 includes a fixed arm 42a that can project in a substantially horizontal direction, and is attached to the casing 41a. And the front-end | tip part of the fixed arm 42a is contact | abutted to the inner wall of the cylindrical body 11 installed after excavation, and the main-body part 44 is hold | maintained.

  The drive mechanism 43 includes a rotation device 43a and a propulsion device 43b. The propulsion device 43b is a hydraulic jack that can be expanded and contracted in the vertical direction. The propulsion device 43b is fixed to the inner peripheral surface of the fixed arm 42a and the main body 44 is fixed. The excavating blade 41b is extended so as to press fit into the ground. After the end of one stroke, the fixing by the fixed arm is released, the propulsion device 43b is contracted, and the main body 44 is moved downward by one stroke. And the cylindrical body 11 installed in the small bore shaft 10 sinks with excavation, and the cylindrical body 11 is added from the ground part 2. When these steps are repeated and the predetermined depth is reached, excavation of the small-diameter shaft 10 by the shaft excavator 40 is completed, and the shaft excavator 40 is removed.

  Next, as shown in FIG. 3B, a step of placing a plurality of curved pipe rules 21, 21,... From the lower inner peripheral wall 10a of the small-diameter shaft 10 is performed (second step). Specifically, a press-fitting device such as an earth auger (not shown) is installed at a place where the curved pipe roof 21 is placed, and the curved pipe roof 21 is propelled in an arc shape. The curved pipe roof 21 is divided into a plurality of length directions, and is placed by a predetermined length (number) while sequentially connecting them. Furthermore, concrete, mortar, cement milk or the like is filled into the steel pipe of the curved pipe roof 21 placed in the ground.

The curved pipe roofs 21, 21,... Constructed in this way have an effect of supporting the natural ground above them from below, and the inner space of the enlarged diameter portion 20 and the roof of the large-diameter vertical shaft 30 (roof) ) To protect the construction of the large diameter shaft 30.
And the 1st support ring member 22 is arrange | positioned to the lower inner peripheral wall 10a over the whole circumference in the shaft periphery direction, the 1st support ring member 22 and the attaching part 21a of each curved pipe roof 21 are fixed, and the small diameter shaft 10 is made. Reinforce to support.

  Subsequently, as shown in FIG. 3C, excavation of the inner space 20a of the plurality of curved pipe roofs 21, 21,... Installed along the shaft circumferential direction is performed (third step). Specifically, while excavating, concrete is sprayed between the curved pipe roofs 21, 21 to form a sprayed portion 23 (see FIG. 1). When excavating to the vicinity of the front end 21b of the curved pipe roof 21, the second support ring member 24 is installed along the vertical shaft circumferential direction inside the front ends of all the curved pipe roofs 21, 21,. 21 and 21 are reinforced by connecting more firmly.

Thereafter, as shown in FIG. 2, a process of excavating the large diameter shaft 30 by digging down the enlarged diameter portion 20 with NATM is performed (fourth process). Specifically, excavation, shotcrete 31 and rock bolt 32 placement are repeated sequentially for each predetermined depth to construct a large-diameter shaft 30 with a predetermined cross-section (depth), and to construct the main shaft 1 Is completed.
In addition, in the large diameter shaft 30, for example, when a sand layer exists, excavation is performed after water stop injection before excavation.

  Thus, the curved pipe roof 21 can reliably support the natural ground above the enlarged-diameter portion 20 from below, so that the loose natural ground is suppressed even in soft ground such as in urban areas. Can do. And under the roof part formed of the curved pipe roof 21, the space inside the enlarged diameter part 20 and the large diameter shaft 30 can be excavated safely.

  Furthermore, the ratio of the outer diameter of the large-diameter shaft 30 to the outer diameter of the small-diameter shaft 10 can be increased. In addition, the outer diameter ratio of the large-diameter shaft 30 to the small-diameter shaft 10 is about twice. That is, if the outer diameter ratio is double, the cross-sectional area ratio of the shaft 1 is four times. Therefore, the occupation area of the ground portion 2 (the cross-sectional area of the small-diameter shaft 10) is almost 1/4 of that of the large-diameter shaft 30, and the excavation amount of the small-diameter shaft 10 is also almost 1/4, so the construction period can be shortened. At the same time, construction costs can be reduced.

  As described above, in the shaft and the construction method thereof according to the present embodiment, the enlarged-diameter portion 20 is constructed using the high-rigidity curved pipe roof 21, so that even in soft ground such as urban areas, the ground The diameter-expanded portion 20 can be constructed without loosening the mountain, and a large-diameter shaft 30 with a larger ratio of the outer diameter to the outer diameter of the small-diameter shaft 10 can be provided below the diameter-expanded portion 20. . Therefore, since the outer diameter of the small-diameter shaft 10 can be made smaller than the outer diameter of the large-diameter shaft 30, the occupation area of the shaft 1 necessary for the ground portion 2 can be reduced, and a work yard like an urban area. Even under narrow construction conditions, the large-diameter shaft 30 can be constructed under the shaft.

  Moreover, since it becomes the construction which excavates the space inside after constructing the curved pipe roof 21, it can excavate safely compared with the case where it constructs by repeating the continuous support by the conventional NATM. In addition, the construction period can be shortened.

As mentioned above, although the embodiment of the shaft according to the present invention and the construction method thereof has been described, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the scope of the present invention.
For example, in the present embodiment, the shaft 1 having the large-diameter shaft 30 is provided below the enlarged-diameter portion 20, but the large-diameter shaft 30 is not constructed, that is, the small-diameter shaft 10 and only the enlarged-diameter portion 20 below the shaft 20. It may be a shaft with a structure.
In this embodiment, the space between the curved pipe roofs 21 and 21 is constructed with shotcrete. However, the present invention is not limited to this, and depending on the ground conditions and the distance between the curved pipe roofs 21, a lock bolt may be applied. It does not matter if it is set up.

  Moreover, although the small diameter shaft 10 is constructed | assembled using the shaft excavator 40 and the large diameter shaft 30 is constructed | assembled by NATM in this Embodiment, it is not limited to this.

It is a partially broken perspective view which shows the whole structure of the shaft by embodiment of this invention. It is a longitudinal cross-sectional view of the shaft shown in FIG. (A)-(c) is a figure which shows the construction process of a shaft. It is a figure which shows the outline | summary of a shaft excavator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical shaft 2 Ground part 10 Small-diameter vertical shaft 10a Lower inner wall part 20 Large diameter part 21 Curved pipe roof 22 1st support ring member (1st support member)
30 Large-diameter vertical shaft 40 Vertical shaft excavator

Claims (6)

A shaft having a small-diameter shaft and an enlarged diameter portion below the shaft,
The diameter-expanded portion has a structure in which a plurality of curved pipe roofs are driven outward in the radial direction of the small-diameter shaft from the small-diameter shaft to the entire outer periphery. .   The shaft according to claim 1, wherein a first support ring member is fixed to an inner peripheral wall of the small-diameter shaft along the shaft circumferential direction.   3. The second support ring member is fixed to the plurality of the curved pipe roofs along the vertical shaft circumferential direction so as to connect the respective front end portions thereof. 4. Shaft.   The shaft according to any one of claims 1 to 3, further comprising a large-diameter shaft having a diameter larger than that of the small-diameter shaft below the enlarged-diameter portion. A first step of excavating a small bore shaft from the ground,
A second step of driving a plurality of curved pipe roofs from the small-diameter shaft to the outside of the small-diameter shaft over the entire outer circumference;
A third step of excavating the inside of the curved pipe roof that has been placed to form an enlarged diameter portion;
A method for constructing a vertical shaft characterized by comprising:   The shaft construction method according to claim 5, wherein a large-diameter shaft having a diameter larger than that of the small-diameter shaft is excavated below the enlarged-diameter portion.

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