JP2000204888A - Pit mouth tunnel and its construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a pit mouth tunnel easily without increasing a cost. SOLUTION: Box-shaped long elements 15 are installed on a foundation 13, and the side parts of the elements 15 are connected to each other in order for assembly. When connecting the elements 15, a PC steel wire is disposed on fixing piece parts of side plates 21 on the outside of 2nd to 4th elements 15 and locking piece parts 33 formed on supporting plates 31 of the foundation 13, and tensed for supporting. While the elements 15 are assembled, concrete is filled into the elements to fill concrete into the entire elements 15 in which the side parts connected to each other form truss parts 22 in order to construct a side wall part 12a with elements 15 formed integrally with concrete. Precast boards 51 assembled in arch shape by butting them with each other are installed on the upper end part of the side wall part 12a so as to construct a roof part 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wellhead tunnel constructed at an end of a tunnel and constituting an entrance and exit of the tunnel, and a method for constructing the tunnel.

[0002]

2. Description of the Related Art Conventionally, as a method of constructing a tunnel, there has been known a method of drilling an excavation hole in the ground, driving an anchor into the excavation hole and spraying concrete, and further performing a secondary lining on the inner surface. Have been.

When a tunnel is constructed as described above, as shown in FIG. 11, the wellhead is a cutting edge having a risk of falling rocks.
Then, a wing 3 that protrudes around was constructed to block the ground G.

[0004] By the way, the wings 3 for retaining the earth are
Since a great deal of trouble and danger is required for the construction, as shown in FIG. 12, it is necessary to construct a wellhead tunnel 4 extending from the tunnel 1 in an unstable ground part having a length of several tens of meters from the wellhead 2. Is being done.

[0005] In order to construct this wellhead tunnel 4, first, an inner formwork forming the inner surface of the wellhead tunnel 4 is supported by a support, and a reinforcing bar is arranged outside the inner formwork. The outer formwork was supported on the outside, and concrete was cast between the inner formwork and the outer formwork. As a construction method that replaces the above-mentioned in-situ casting, as shown in FIGS. 13 and 14, a precast plate 5 formed by a molding die is butted together at the site and assembled into an arch shape to construct a wellhead tunnel 4. There is.

[0006]

In the case of constructing the tunnel 4 by casting in the field, there is a problem that extremely complicated operations such as installation and removal of the inner formwork and the outer formwork are required. However, since a supporter for supporting these forms is required, there is a problem that a great deal of labor is required for installation and removal of the supporter.

When the precast plate 5 is used, the precast plate 5 needs to have a stable structure.
Since it is necessary to reduce the size of the precast plate 5 to three or less, the miniaturization of the precast plate 5 is limited.
However, there is a problem that manufacturing, transportation, installation, and the like become difficult due to the inevitable increase in size of the device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wellhead tunnel that can be easily and quickly constructed without increasing the cost, and a method of constructing the tunnel. I have.

[0009]

In order to achieve the above object, a wellhead tunnel according to claim 1 is a wellhead tunnel constructed at an end of the tunnel and constituting an entrance and exit of the tunnel, and has a reinforcing steel bar therein. Is formed in a box shape in which
A pair of parallel side walls provided by filling concrete in a long element whose side parts are joined together and assembled, and a precast assembled by abutting each other on the upper side of the side wall in the tunnel circumferential direction. It is characterized by being composed of a ceiling made of a plate.

[0010] As described above, the side wall is formed by joining the side parts together and is filled with concrete in a box-shaped long element, and the precast plate provided at the upper end of the side wall. Since the structure is used, compared with the construction using cast-in-place concrete using a formwork, the formwork and the supporting structure for supporting the formwork are not required, thereby setting and removing the formwork and the supporting structure. This eliminates the need for complicated work.

The wellhead tunnel according to the second aspect is the first aspect.
The wellhead tunnel according to any one of the preceding claims, characterized in that the elements are connected to each other in a truss structure, and the concrete is filled over the elements connected to each other.

That is, since the joining side of the elements has a truss structure and is an integrated structure in which the elements are filled with concrete, the strength is enhanced.

According to a third aspect of the present invention, there is provided a method of constructing a wellhead tunnel constructed at an end of a tunnel and constituting an entrance and exit of the tunnel, wherein a box-shaped rebar is provided inside. By joining the side parts of the long element to each other and assembling them, filling these elements with concrete and integrating them, a pair of side wall parts is constructed parallel to each other, and the upper end of these side wall parts is placed in the tunnel circumferential direction. It is characterized by assembling a precast version that is matched to the ceiling to construct the ceiling.

As described above, by joining the side parts of the element to each other and assembling them, and filling the element with concrete, it is possible to extremely easily construct the side wall composed of the element filled with concrete inside.
Further, by assembling the precast plate on the upper end of the side wall portion, the wellhead tunnel is easily constructed. This makes it possible to eliminate the need for a formwork and a shoring for supporting the formwork, as compared with a case where a wellhead tunnel is constructed from cast-in-place concrete using the formwork.
Extremely complicated work such as installation and removal of the formwork and the shoring is eliminated, and the construction period is shortened.

According to a fourth aspect of the present invention, there is provided the method of constructing a wellhead tunnel according to the third aspect.
When the element is joined in order from a pre-constructed base portion to assemble into an arch shape, the outer surface of the element and the base portion are connected by a PC steel wire, and the PC steel wire is tensioned to connect the element. It is characterized by support.

As described above, since the element is assembled while being supported by being pulled by the PC steel wire from the outside, the support from the inside is unnecessary, and the support work on the inside is unnecessary. In other words, since the inner support is not required, for example, even in the case of construction in an existing tunnel, by opening a protective frame and the like inside to protect the traveling lane of the vehicle, to open the traffic Element assembly can be performed.

According to a fifth aspect of the present invention, there is provided a method of constructing a wellhead tunnel according to the third aspect.
The invention is characterized in that the elements are joined by assembling in order from a previously constructed base portion while being supported by a support member made of a steel material arranged in an arch shape along the inner peripheral surface of the tunnel.

As described above, since the support member made of a steel material arranged in an arched shape along the inner peripheral surface of the tunnel is supported, the work of assembling the elements can be facilitated. It is advantageous when

According to a sixth aspect of the present invention, there is provided the method for constructing a wellhead tunnel according to any one of the third to fifth aspects, wherein the elements to be joined to each other have a truss structure. It is characterized in that concrete is filled in these elements.

In other words, since elements having a truss structure on the sides to be joined to each other are used, by filling the elements with concrete, it is very easy to spread the concrete throughout the assembled elements and to ensure that the elements are connected to each other. A wellhead tunnel having a high-strength side wall integrated into the tunnel is constructed.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a wellhead tunnel and a method for constructing the same according to the present invention. FIG.
2 and FIG. 2, reference numeral 11 denotes a wellhead tunnel.
The wellhead tunnel 11 has an arched wellhead body 12 and a foundation 1 on which both ends of the wellhead body 12 are installed.
3 and a bottom plate portion 14 provided between the foundations 13.
It is schematically composed of

The wellhead body 12 has side walls 12 on both sides.
a, an intermediate portion is a ceiling portion 12b, and a decorative plate 16 is provided on an inner peripheral surface of the side wall portion 12a. As shown in FIG. 3, the side wall portion 12a is composed of a plurality of box-shaped long elements 15 whose side portions are joined to each other in the circumferential direction, and the element 15 whose side portions are joined to each other. In the entire interior, concrete C
Are filled and integrated.

As shown in FIG. 4, the element 15 is
A pair of side plates 21 provided facing each other, and provided between these side plates 21, these side plates 21 are
And a truss portion 22 joined at an interval. The width dimension of both side plates 21 of the element 15 is small on the inside and large on the outside. That is,
When the side parts of the elements 15 are joined together, they can be assembled into a polygonal arch as a whole.

The element 15 to be joined to the uppermost part
The width of the outer side plate 21 is smaller than that of the inner side so that the upper part of the side wall part 12a is substantially horizontal. Further, the side plate 21 of each of the elements 15 is provided with a joint member 23 formed in a hook shape at an upper portion thereof, and a projection 24 with which the joint member 23 can be engaged is provided at a lower portion thereof.

That is, when another element 15 is joined to the upper part of the element 15, the lower element 15
The upper element 15 is placed in a state shifted in the axial direction with respect to, and then the upper element 15 is slid in a direction opposite to the shifted direction, so that the projection 24 of the upper element 15 is moved downward. It is adapted to be engaged with the joint member 23 of the element 15.

The joint member 23 may be provided below the side plate 21 and the projection 24 may be provided above the side plate 21 so that they are engaged with each other. And, the element 15 having the above configuration is provided with a cage-type reinforcing bar 25 therein to form a unit.

The foundation 13 is provided with anchor bars 26 extending upward, and the wellhead body 12 is fixed to the foundation 13 by the anchor bars 26. Also, on the foundation 13, on the outer peripheral side at the lower end of the wellhead body 12,
A support plate 31 stands upright in the longitudinal direction.

As shown in FIG. 5, the support plate 31
A plurality of locking pieces 33 having the recesses 32 are provided at intervals in the axial direction. The locking pieces 33 are formed as a set of three in the axial direction, and each of the locking pieces 33 is a first locking piece 33.
a, a second locking piece 33b and a third locking piece 33c.

The first locking piece 33a, the second locking piece 33b, and the third locking member 33 are provided on the side plate 21 outside the second lowermost element 15 of the elements 15 constituting the wellhead main body 12. The top member 34 is provided at the same axial position as the stop piece portion 33c, and further, at the same axial direction position as the first locking piece portion 33a, above the top member 34, the locking piece portion 3 is provided.
A fixing piece 35 having substantially the same shape as that of the fixing piece 3 is provided.

The outer side plate 21 of the third element 15 from the bottom of the element 15 is provided at the same axial position as the second locking piece 33b and the third locking piece 33c.
A top member 34 is provided, and at the same axial position as the second locking piece 33b, above the top member 34,
A fixing piece 35 is provided.

Further, on the side plate 21 outside the fourth element 15 from the bottom of the element 15, a top member 34 is provided at the same axial position as the third locking piece 33c. A fixing piece 35 is provided above the top member 34 at the same axial position as the third locking piece 33c.

The locking piece 33 and the fixing piece 35
A fixing PC steel wire 41 to be described later is arranged between the fixing member 35 and a fixing nut 41a provided at one end of the PC steel wire 41. The tensioning nut 41 b provided on the other end side is locked by the locking piece 33. Here, this PC
The steel wire 41 has threads formed at both ends, and the fixing nut 41a and the tensioning nut 41b
Are screwed together.

In the wellhead main body 12 of the wellhead tunnel 11 configured as described above, a PC steel wire (not shown) is disposed so as to extend in the circumferential direction and at intervals in the axial direction. This introduces a prestress in the circumferential direction.

The ceiling portion 12b is composed of a precast plate 51. One end of each precast plate 51 is a joint end 51a to be joined to each other.
It is fastened and fixed by nuts and the like. These precast plates 51 are formed from high-strength concrete and have a reduced thickness.

The other end of the precast plate 51, which constitutes both ends of the ceiling 12b, is a connection end 51b with the upper end of the side wall 12a. The connecting end 51b is formed with a flange portion 52 protruding in the outer peripheral direction and has a thickness substantially equal to the thickness of the side wall portion 12a.
A plurality of communication holes 53 are formed in the flange portion 1b at intervals in the tunnel axis direction.

The communication hole 53 has a side wall 12.
A connecting bar 54 erected at the upper end of b is inserted. The connecting bar 54 has an upper end protruding above the flange portion 52 of the precast plate 51, and a nut 50 is screwed and fastened to the protruding portion.

Next, the construction of the wellhead tunnel 11 will be described with reference to FIG. (Construction of Side Wall 12a) (1) First, a foundation 13 is constructed, a first-stage element 15 is arranged in accordance with a support plate 31 of the foundation 13, and concrete C is filled in the element 15. (2) Next, when the second-stage element 15 is placed on the upper part of the element 15 so as to be shifted in the axial direction, the second-stage element 15 is slid in a direction opposite to the direction in which the second-stage element 15 is shifted. .

In this way, the projection 24 provided below the side plate 21 of the second stage element 15
The first-stage element 15 and the second-stage element 15 are engaged with each other by being engaged with a joint member 23 provided above the side plate 21 of the first-stage element 15.

(3) As described above, when the second-stage element 15 is joined to the first-stage element 15, as shown in FIG.
The fixing nut 41a fixed to one end of the PC steel wire 41 is locked to the fixing piece 35 provided on the base 13 and the first locking piece 33a provided on the support plate 31 of the foundation 13 is fixed to the PC by the PC. The tension nut 41b screwed to the other end of the steel wire 41 is locked.

(4) Next, the tension nut 41b screwed to the other end is further screwed in to tension the PC steel wire 41. In this case, the element 15 in the second stage is
It is supported by being pulled from the outside by the PC steel wire 41,
The second stage element 15 is prevented from falling inside.

At this time, when the PC steel wire 41 comes into contact with the top member 34 provided on the outer side plate 21 of the second stage element 15, the contact portion is curved,
This PC steel wire 41 is used for the element 15 of the first and second stages.
They are tensed without coming into contact with their joints. This ensures that the tension of the PC steel wire 41 acts on the second-stage element 15.

(5) In this state, the concrete C is filled in the second stage element 15. (6) After that, the third-stage element 15 is placed on the upper part of the second-stage element 15 in the axially displaced state in the same manner as described above, and the third-stage element 15 is displaced. And slide in the opposite direction.

In this manner, the projection 24 provided below the side plate 21 of the third stage element 15
The second-stage element 15 and the third-stage element 15 are engaged with each other by being engaged with a joint member 23 provided above the side plate 21 of the second-stage element 15.

(7) Thus, the third stage element 1
5 is joined to the second-stage element 15, a fixing nut 41 a fixed to one end of the PC steel wire 41 is attached to the fixing piece 35 provided on the side plate 21 outside the third-stage element 15. The tension nut 41b screwed to the other end of the PC steel wire 41 is locked to the second locking piece 33b provided on the support plate 31 of the base 13.

(8) Next, the tension nut 41b screwed to the other end is further screwed in to tension the PC steel wire 41. In this case, the third stage element 15
It is supported by being pulled from the outside by the PC steel wire 41,
The third stage element 15 is prevented from falling inside.

At this time, the PC steel wire 41 is connected to the outer side plate 2 of each of the third-stage and second-stage elements 15.
When the PC steel wire 41 is in contact with the top member 34 provided in the first stage, the contact portion is bent,
It is tensed without coming into contact with the joints between the elements 15 in the first stage and between the elements 15 in the first and second stages. This ensures that the tension of the PC steel wire 41 is 3
It acts on the element 15 of the stage.

(9) In this state, the concrete C is filled in the third stage element 15. (10) Further, 4
The stage element 15 is placed in a state shifted in the axial direction in the same manner as described above, and the fourth stage element 15 is slid in the direction opposite to the direction shifted.

In this way, the projection 24 provided below the side plate 21 of the fourth stage element 15
The third-stage element 15 is engaged with a joint member 23 provided above the side plate 21 of the third-stage element 15, and the third-stage element 15 and the fourth-stage element 15 are joined to each other.

(11) As described above, when the fourth stage element 15 is joined to the third stage element 15, the fixing piece 35 provided on the side plate 21 outside the fourth stage element 15 The fixing nut 41a fixed to one end of the steel wire 41 is locked, and screwed to the third locking piece 33c provided on the support plate 31 of the base 13 to the other end of the PC steel wire 41. The tension nut 41b is locked.

(12) Next, the tension nut 41b screwed to the other end is further screwed in to tension the PC steel wire 41. In this way, the fourth stage element 15
Is pulled from the outside by the PC steel wire 41 and is supported, so that the fourth stage element 15 is prevented from falling inside.

At this time, the PC steel wire 41 comes into contact with the top member 34 provided on the outer side plate 21 of each of the fourth, third, and second stage elements 15, thereby causing the contact. The section is curved, and this PC steel wire 41
Elements 15 of the fourth and fourth stages, elements 15 of the second and third stages, and elements 1 of the first and second stages
It is tensed without coming into contact with the joint between the five. This ensures that the tension of the PC steel wire 41 acts on the fourth stage element 15.

(13) In this state, the concrete C is filled in the fourth stage element 15. (14) When the concrete C has hardened, the PC steel wire (not shown) inserted in the element 15 in advance in the circumferential direction is tensioned, so that the side wall 12a to which the prestress is introduced and the strength is increased. After completion, the decorative plate 16 is attached to the inner peripheral surface side. Each element 15
Is closed so that the concrete C to be filled does not flow out.

(Construction of Ceiling Part 12b) (15) Next, the side wall part 12a constructed as described above
A precast plate 51 is set at the upper end of the plate. That is, the connecting end 51b is placed on the side wall 12a while the connecting bar 54 provided at the upper end of the side wall 12a is inserted into the communication hole 53 formed in the flange 52 constituting the connecting end 51b of the precast plate 51. The joining ends 51a of the precast plate 51 are abutted against each other and joined by bolts and nuts.

Further, a nut 50 is screwed into the connecting bar 54, and the flange 52 of the precast plate 51 is attached to the side wall 12.
a.

(16) Between the foundations 13, the bottom slab 14
Then, the decorative tunnel 16 is adhered to the inner surface of the wellhead main body 12 to complete the wellhead tunnel 11, and then the wellhead tunnel 11 is backfilled. In addition, the PC steel wire 41 used at the time of assembling the elements 15 is removed after the completion of the wellhead tunnel 11 and used at the time of building another wellhead tunnel. The work such as the construction of the bottom plate portion 14 inside the wellhead main body 12 can be performed in parallel with the construction of the wellhead main body 12.

As described above, according to the above-described wellhead tunnel 11, the side wall portion 12a filled with concrete C is filled in the box-shaped long element 15 assembled in an arch shape by joining the sides. Since it is composed of the precast plate 51 provided at the upper end portion of the side wall portion 12a, it is possible to provide a formwork and a support structure for supporting the formwork in comparison with those constructed by cast-in-place concrete using the formwork. Can be dispensed with, thereby making it possible to eliminate extremely complicated operations such as installation and removal of the formwork and the shoring. In addition, by increasing the length of the element 15, the length of the wellhead tunnel 11 can be extremely easily increased.

Further, the joining side of the elements 15 is a truss portion 22 of a truss structure, and
Since it is an integral structure in which the concrete C is filled over each other, the strength of the side wall portion 12a can be enhanced.

According to the construction method for constructing the wellhead tunnel 11, the side walls 12a are constructed by joining the sides of the elements 15 to each other and filling the element 15 with the concrete C. By mounting the precast plates 51 against each other at the upper part of the element 12a, it is very easy to
The wellhead tunnel 11 composed of the side wall part 12 a composed of the precast plate 51 and the intermediate part composed of the precast plate 51 can be constructed.

That is, as described above, the formwork and the support for supporting the formwork can be dispensed with, as compared with the case where the wellhead tunnel is constructed by cast-in-place concrete using the formwork. In addition, it is possible to eliminate extremely complicated work such as installation and removal of the formwork and the shoring work, to shorten the construction period, and to increase the length of the element 15 so that the wellhead tunnel 11 can be extremely easily mounted. The length can be lengthened.

Further, a side wall portion 12a forming both side portions,
And a ceiling portion 12b which is connected to the upper end of the side wall portion 12a and constitutes the upper portion of the wellhead main body 12. Since the ceiling portion 12b is formed of the precast plate 51 which is abutted and joined to each other, the wellhead body As compared with the case where all the members 12 are formed of precast plates joined to each other by abutting each other, the precast plate 51 can be significantly reduced in size.

As a result, it is possible to reduce the size of the mold for forming the precast plate 51 and the reinforcing bars provided inside the precast plate 51, as well as to eliminate the need for a large overhead crane, thereby reducing equipment and manufacturing costs. Can be planned. Also,
With the miniaturization of the precast plate 51, the size of the cargo,
These precast plates 51 can be easily loaded and transported on a truck having a limited loading weight.

Moreover, a large stock yard is not required in a factory or on-site, and heavy equipment such as a large crane is not required on-site, so that restrictions on the on-site can be eased. Further, since the element 15 is assembled in an arch shape while being supported by being pulled from the outer side plate 21 by the PC steel wire 41, it is possible to eliminate the need for support from the inside, and to eliminate the need for support on the inside. it can.

In other words, since the inner shoring is not required, for example, even when the tunnel is installed in an existing tunnel, FIG.
As shown in (1), by installing a protection frame 61 inside to protect the traveling lane of the vehicle S, it is possible to open the traffic and to assemble the element 15.

Moreover, since the elements 15 having the truss portions 22 of the truss structure are used at the side portions to be joined to each other, the concrete C is filled with the concrete C very easily over the elements 15 by filling the concrete C. Thus, it is possible to construct the arched wellhead tunnel 11 having the high-strength side wall 12a in which the elements 15 are surely integrated.

Further, since the engaging members 23 and the projections 24 provided at intervals in the longitudinal direction of the elements 15 are engaged with each other, the upper and lower elements 15 are joined while being shifted from each other. By making the side portions of the side contact each other and sliding in the direction opposite to the shifted direction, the engaging member 23 of each element 15 and the protruding portion 24 can be very easily engaged with each other, 1
5 can be connected to each other.

Also, by cutting the end of the element 15 obliquely, the wellhead tunnel 11
As shown in FIG. 8, a so-called bamboo split structure in which the end is inclined in accordance with the inclination of the ground on the side can be employed.

In FIG. 9, instead of the foundation 13 and the bottom plate portion 14, an invert 62 in which the base portion and the bottom plate portion are integrated is constructed, and the wellhead main body 12 is attached to the base portion of the invert 62. According to the wellhead tunnel 11 having this structure, the wellhead tunnel 11 can be easily constructed even in a place with bad ground.

The portion of the invert 62 may be constructed by a plurality of elements similar to the element 15. That is, the elements may be joined to each other in the horizontal direction and the interior thereof may be filled with concrete, so that the elements may be integrated with concrete to form an invert.

In the above example, the element 15 having the flat side plate 21 is used. However, the element 15 in which the side plate 21 is curved in accordance with the arch shape may be used. In the above example, screws are formed on both ends of the PC steel wire 41, and the fixing nut 41a and the tension nut 41b are screwed to these male screws, but one end has a screw structure. Instead, a structure in which a locking portion that can be simply locked to the fixing piece 35 may be provided.

As another method of constructing the wellhead tunnel 11 using the above-described element 15, especially when constructing a wellhead tunnel 11 of a new tunnel, as shown in FIG. At a plurality of locations, support members 63 in which steel materials such as H steel are assembled in an arch shape are installed,
It is also possible to construct the wellhead main body 12 by assembling the element 15 and filling with the concrete C while supporting the support member 63.

[0071]

As described above, according to the wellhead tunnel and the method of constructing the same according to the present invention, the following effects can be obtained. According to the wellhead tunnel according to the first aspect, the precast plate is abutted against the side wall portion filled with concrete in the box-shaped long element assembled by joining the side portions to each other, and the upper end of the side wall portion. Since it is composed of a ceiling part, compared with the construction using cast-in-place concrete using a formwork, a formwork and a shoring for supporting the formwork are not required. Extremely complicated work such as installation and removal of the shoring works can be eliminated. In addition, the ends of the elements may be inclined so that the ends of the wellhead tunnel have a bamboo split structure.

According to the wellhead tunnel according to the second aspect, the joining side of the elements has a truss structure, and the side walls have an integrated structure in which concrete is filled over the elements, so that the strength is increased. Can be planned.

According to the method for constructing a wellhead tunnel according to the third aspect of the present invention, the elements are assembled by joining the sides of the elements to each other, and the element is filled with concrete, whereby the element is made of an element filled with concrete. By constructing the side wall portion and arranging the precast plate on the upper portion of the side wall portion, the wellhead tunnel can be constructed extremely easily. Thereby, compared with the case of constructing a wellhead tunnel by cast-in-place concrete using the formwork, it is possible to eliminate the need for the formwork and the shoring for supporting the formwork. Extremely complicated work such as installation and removal can be eliminated, and the construction period can be shortened.

According to the method of constructing a wellhead tunnel according to the fourth aspect, the element is assembled while being supported by being pulled from the outside by the PC steel wire, so that the support from the inside can be eliminated, and the support on the inside can be eliminated. Work can be eliminated. In other words, since the inner shoring is not required, for example, when constructing an existing tunnel,
By installing a protective frame or the like inside to protect the traveling lane of the vehicle, it is possible to open the traffic and to assemble the element.

According to the method for constructing a wellhead tunnel according to the fifth aspect, the element is supported by the support member made of a steel material arranged in an arched shape along the inner peripheral surface of the tunnel, thereby facilitating the assembling work of the element. This is particularly advantageous when constructing a new tunnel.

According to the method for constructing a wellhead tunnel according to the sixth aspect, since the elements to be joined to each other have the truss structure, the elements are extremely easily assembled by filling the elements with concrete. Concrete can be spread all over the inside of the inside, and an arched wellhead tunnel having a high-strength side wall portion in which elements are surely integrated can be constructed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a wellhead tunnel illustrating a configuration and a structure of a wellhead tunnel according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the wellhead tunnel illustrating the configuration and structure of the wellhead tunnel according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a part of the wellhead tunnel illustrating a configuration and a structure of the wellhead tunnel according to the embodiment of the present invention.

FIG. 4 is a perspective view of an element used in the wellhead tunnel for describing a configuration and a structure of the wellhead tunnel according to the embodiment of the present invention.

FIG. 5 is a plan view of a locking piece provided on a support plate for explaining the configuration and structure of the wellhead tunnel according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view of a part of the wellhead tunnel during assembly for explaining the method of constructing the wellhead tunnel according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view of a wellhead tunnel for explaining a case of building a wellhead tunnel in an existing tunnel by the method for building a wellhead tunnel according to the embodiment of the present invention.

FIG. 8 is a perspective view of a wellhead tunnel illustrating an end structure of the wellhead tunnel according to the embodiment of the present invention.

FIG. 9 is a sectional view of a wellhead tunnel illustrating a configuration and a structure of a wellhead tunnel according to another embodiment of the present invention.

FIG. 10 is a sectional view of a wellhead tunnel illustrating another method for constructing the wellhead tunnel according to the embodiment of the present invention.

FIG. 11 is a cross-sectional view of a ground where a tunnel is constructed, illustrating a general tunnel construction method.

FIG. 12 is a cross-sectional view of the ground where a tunnel having a wellhead tunnel is described, illustrating a conventional technique of the wellhead tunnel.

FIG. 13 is a cross-sectional view of the ground where a tunnel having a wellhead tunnel is described, illustrating a conventional technique of the wellhead tunnel.

FIG. 14 is a perspective view of a wellhead tunnel for explaining a conventional technique of the wellhead tunnel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Well tunnel 12a Side wall part 12b Ceiling part 13 Foundation 15 Element 21 Outer side plate (outer surface) 22 Truss part (truss structure) 25 Reinforcing bar 41 PC steel wire 51 Precast plate 63 Support member C Concrete

Claims (6)

[Claims] 1. A wellhead tunnel constructed at an end of a tunnel and constituting an entrance and exit of the tunnel, formed in a box shape having a reinforcing bar disposed inside, and assembled by joining side parts to each other. It is composed of a pair of parallel side walls formed by filling concrete in a long element, and a ceiling part made of a precast plate that is assembled on top of the side wall parts by abutting each other in a tunnel circumferential direction. Wellhead tunnel. 2. The wellhead tunnel according to claim 1, wherein said elements are connected to each other in a truss structure, and said concrete is filled over said elements. 3. A method of constructing a wellhead tunnel constructed at an end of a tunnel and constituting an entrance and exit of the tunnel, wherein side parts of a box-shaped long element in which a reinforcing bar is disposed are joined to each other. By assembling and filling these elements with concrete and integrating them, a pair of side walls are constructed parallel to each other, and at the upper ends of these side walls,
A method for constructing a wellhead tunnel, comprising assembling a precast plate that is to be abutted in a circumferential direction of the tunnel to construct a ceiling. 4. An outer surface of the element and the base portion are connected to each other by a PC steel wire when the elements are sequentially joined from a pre-constructed base portion and assembled in an arch shape, and the PC steel wire is strained. 4. The method according to claim 3, wherein the element is supported by the support. 5. The assembly according to claim 3, wherein the elements are joined in order from a pre-established base portion while being supported by a support member made of a steel material arranged in an arch shape along the inner peripheral surface of the tunnel. The method of constructing a wellhead tunnel as described. 6. The element as claimed in claim 3, wherein said elements having a truss structure on the side to be joined to each other are assembled, and said elements are filled with concrete.
The method for constructing a wellhead tunnel according to any one of the above items.