JPH05179899A - Construction method of underground cavity - Google Patents

Abstract

PURPOSE:To construct an underground cavity of large cross section for an underground power plant, an oil storage tank, or the like efficiently in the rock-bed. CONSTITUTION:In the rock-bed A, tunnels 2a, 2b... of rectangular cross section and desired height, and closed ring-shape linkings 3a, 3b... formed by concrete placing to the inside of the tunnels are formed successively in the stacked state along the border line of a planned underground cavity B from its lower end part to its top part, thus constructing a dome lining C to be the wall body of the planned underground cavity B. The rock-bed D surrounded by the dome lining C is then excavated down from the top side to construct the underground cavity D.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for constructing a large-scale hemispherical or dome-shaped underground cavity having a diameter of several tens to 100 m, such as an underground power plant or an underground tank for oil storage, in bedrock. It is about.

[0002]

2. Description of the Related Art Conventionally, as a method of constructing such a large-scale underground cavern in bedrock, first, a portion corresponding to the upper end of the planned underground cavern is excavated in the bedrock, and then the excavated wall surface is excavated. A construction method is used in which concrete lining is applied, and then the bench cut method is used to sequentially dig the rock in the planned underground cavity at appropriate depths while sequentially lining the excavated wall.

[0003]

However, according to such a method, concrete lining is sequentially performed every time a wide rock area having a suitable height in the planned underground cavity is excavated. Since the rock excavation work requires a great deal of work and cannot be moved to the next lining work unless the work is completed, there is a problem that the work efficiency is poor and the construction period is significantly prolonged.

Further, when excavating by bench cut, the rock is destroyed by blasting, but the vibration at the time of blasting is transmitted to the concrete lining under construction and the lining is cracked. There were problems such as vibration pollution in the surrounding area. It is an object of the present invention to provide a novel method for constructing an underground cavern capable of completely eliminating such problems.

[0005]

In order to achieve the above object, the method for constructing an underground cavity of the present invention is to excavate a closed annular tunnel along the lower end of the contour line of a planned underground cavity to be formed in bedrock. After that, concrete is poured into this tunnel to form a lining, and then a closed annular tunnel is excavated along the contour line of the planned underground cavity on the upper side of the lining in the same manner as the closed annular tunnel. After that, a concrete lining is placed in the tunnel to form a continuous lining on the lining, and this work is repeatedly carried out upward along the contour line of the planned underground cavity. The method is characterized by forming a lining of an underground cavity, and then excavating the bedrock in the lining.

Further, in the method of the present invention, when the concrete lining is formed in the closed annular tunnel as described in claim 2, a space is present on the inner peripheral side of the tunnel. As described above, it is desirable that the concrete lining is provided in the tunnel, and excavated shear or foam concrete is placed in the space on the inner peripheral side thereof.

[0007]

[Operation] Concrete lining is performed inside the tunnel while excavating a closed annular tunnel with a predetermined height and width from the bottom to the top along the contour line of the planned underground cavity. The entire lining of the planned underground cavern is formed without excavating the internal rock mass of the cavern. Then, the rock surrounded by this lining is continuously excavated and removed by a bench cut method or the like to form an underground cavity. At this time, when the lining is formed, the inner surface of the lining can be covered with excavation shearing or foam concrete in advance to prevent vibration or the like at the time of blast from directly acting on the lining. Also, it does not cause vibration pollution in the surrounding area.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.
When constructing a large-section underground cavern such as an oil storage tank at a desired location on the bedrock A, first, as shown in FIG. 1, after excavating the access tunnel 1 reaching the lower end of the planned underground cavern B from the outside, A closed annular tunnel 2a having a rectangular cross section of 3 to 4 m square is excavated from the access tunnel 1 along the lower end of the contour line of the planned underground cavity B while being horizontally bent at a predetermined curvature. The closed annular tunnel 2a is not limited to a circular shape as shown in the figure, but may be a rectangular shape or any other suitable shape.

Further, as the excavation means, an appropriate slot excavator is used, and as shown in FIG. 2, a slot having an appropriate depth in the tunnel length direction is formed along the outer circumference of the tunnel cross-section on the rock surface.
11 is continuously formed, and the rock surface surrounded by the outer peripheral slot 11 is also divided by vertical and horizontal slots 12, 13 to form the slot 11
A blast hole 14 is bored in a rock part surrounded by 13 to load explosives and explode to excavate. Further, an appropriate rock excavator can be adopted as needed. The excavated rock is discharged to the outside using the access tunnel 1.

Thus, the closed annular tunnel 2a as described above is formed by sequentially excavating a tunnel portion of an appropriate length along the lower end of the contour line of the planned underground cavity B and connecting them in series. Subsequent to or after excavation of the closed annular tunnel 2a, a formwork is assembled in the tunnel 2a, and as shown in FIG. Form. At this time, the concrete may be poured into the tunnel 2a so that the concrete is entirely filled, but the space 4
It is desirable to form the lining 3a by placing concrete in the tunnel 2a other than the space 4 so that the lining 3a is continuously provided in the tunnel length direction.

On the other hand, as shown in FIG. 5, the working tunnel 5 is excavated in an upward spiral shape so as to communicate with the access tunnel 1 along the inner peripheral side of the contour line of the planned underground cavity B, The upper end is provided up to the inner peripheral surface of the top of the planned underground cavity B, and the vertical shaft 6 is excavated in the vertical direction from the top.
The work tunnel 5 and the vertical shaft 6 may be separately performed before and after the construction of the concrete lining, but it is preferable to perform the work tunnel 5 in parallel with the concrete lining.

Then, after the concrete placed in the closed annular tunnel 2a provided at the lowermost end of the contour line of the planned underground cavity B is hardened, the concrete is lined up on the concrete lining 3a as shown in FIG. As shown in FIG. 4, the next closed annular tunnel 2b along the contour line of the planned underground cavity B is continuously excavated from a part of the spiral inclined work tunnel 5 corresponding to the height position of the closed annular tunnel 2b. To do. At this time, the tunnel 2b may be excavated by the excavation means above the hardened portion without waiting for the concrete lining 3a to be entirely hardened.

A part of the shear of the rock mass crushed during this excavation falls into the space 4 on the inner peripheral side of the concrete lining 3a communicating therewith, and the space 4 is filled with the shear 7. Prevent damage to concrete linings due to blasting during subsequent rock crushing. Instead of filling the space 7 with the shear 7, the space may be filled with a cushioning material such as foamed mortar. Then, a concrete lining 3b is formed in the tunnel 2b excavated in a closed ring, leaving the space 4 on the inner peripheral side in the same manner as described above.
It is integrated on the lower concrete lining 3a.

In this way, concrete linings 3a, 3b, 3c ... are sequentially formed in a stack at predetermined heights along the contour line of the planned underground cavern B to the top of the cavern, as shown in FIG. As shown, a dome-shaped lining C that forms the wall of the planned underground cavity B is formed. In addition, concrete lining 3a, 3b, 3c
As described above, the lining formation tunnels were excavated by using the spiral inclined work tunnel 5 located on the inner peripheral surface side of the height position, but each tunnel 2a, 2b, 2c.・ ・
Since the space portion 4 in which no concrete lining is constructed is formed in this, the space portion 4 may be used to excavate the upper tunnel.

After the formation of the lining C of the planned underground cavity B, the rock mass around the shaft 6 excavated from the top of the lining C during the formation of the lining C or after the formation of the lining C is shown in FIG. A bench cut method that uses crushing by blasting is used to sequentially dig a specified depth. The work tunnel 5 and the shaft 6 are used to carry out the excavated skid and carry in the equipment. At the time of blasting, since the lining C and the bedrock D in the planned underground cavity B are edged by the shear 7 or foam mortar filling the space 4 as described above, the blasting vibration is caused by the shear 7. It is possible to prevent the oil from being absorbed or blocked by the foamed mortar and transmitted to the lining C by being blocked.

In this way, by excavating and removing the bedrock D of the planned underground cavity B surrounded by the lining C to the position of the concrete lining 3a at the bottom, an underground cavity as shown in FIG. 7 is constructed and constructed. Thereafter, if necessary, a floor wall connected to the concrete lining 3a may be formed on the bottom surface by pouring concrete.

[0017]

As described above, according to the method for constructing an underground cavern of the present invention, a tunnel having a cross-sectional shape of a constant height sequentially from the lower end to the top along the contour line of the planned underground cavern is provided. Since the closed annular lining by placing concrete in the tunnel is formed in a stacked state, the dome-shaped lining that will become the wall of the planned underground cavity without first excavating the rock in the planned underground cavity Can be constructed efficiently, and then the rock bed surrounded by this dome-shaped lining is to be excavated, so a large volume of rock bed can be continuously excavated, and work efficiency is significantly improved. However, the construction period can be shortened.

Furthermore, since the rock excavation and crushing work is performed from the top downward in the lining, there is no risk of rock collapse, safe work is possible, and rock around the cavity is not relaxed. Therefore, it is possible to construct a pillarless underground cavity with a large cross section. In addition, by filling the inner peripheral side of each concrete lining that is sequentially stacked with a cushioning material such as shear or foam concrete, the vibration that occurs when the rock in the lining is crushed by blasting With almost no transmission to the lining side, damage to the lining can be prevented, a strong underground cavity can be built, and vibration pollution is not given to the surrounding area.

[Brief description of drawings]

[Figure 1] Simplified perspective view of the planned underground cavity,

FIG. 2 is a front view of a tunnel face for explaining the tunnel excavating means,

FIG. 3 is a cross-sectional view of a concrete lining formed in the lowermost tunnel,

FIG. 4 is a cross-sectional view showing a state in which concrete linings are sequentially formed upwards,

FIG. 5 is a simplified sectional view showing a state in which a vertical shaft and a spiral inclined work tunnel are provided,

FIG. 6 is a simplified cross-sectional view showing an excavated state of rock in the lining,

FIG. 7 is a sectional view of an underground cavity.

[Explanation of symbols]

 2a Closed circular tunnel 2b Closed circular tunnel 3a Concrete lining 3b Concrete lining 4 Space 5 Spiral inclined work tunnel 6 Vertical shaft 7 Buffer material A Rock B Planned underground cavity C Lining D Rock

Claims (2)

[Claims] 1. After excavating a closed annular tunnel along the lower end of the contour line of a planned underground cavity to be formed in rock,
After placing concrete in this tunnel to form a lining, and then excavating the closed annular tunnel along the contour line of the planned underground cavity in the same manner as the closed annular tunnel above the lining, A continuous lining is formed on the lining by placing concrete in the tunnel, and this work is repeatedly performed in the upward direction along the contour line of the planned underground cavity. A method for constructing an underground cavity, which comprises forming a lining, and then excavating rock in the lining. 2. When forming a concrete lining in the closed annular tunnel, the concrete lining is applied to the inside of the tunnel so that there is a space on the inside of the tunnel, and the inside of the tunnel is covered. The method for constructing an underground cavity according to claim 1, wherein excavation shearing or foam concrete is placed in the space.