阅读说明：本技术 一种超大断面双连拱隧道不对称开挖施工组织方法 (Asymmetric excavation construction organization method for super-large section double arch tunnel ) 是由 蔡杰 王学斌 董建松 高海东 史培新 孙磊 魏赟 蔡华忠 颜静 郭彦兵 刘杨 于 2020-12-01 设计创作，主要内容包括：本发明公开了一种超大断面双连拱隧道不对称开挖施工组织方法,包括十六个步骤,通过横纵通道展开双连拱隧道进出洞,保持横通道与隧道进洞协同施工；1#洞保持超前开挖,作为地质先导洞和主运输通道；通过先行开挖导洞,增开横通道,同时展开多个工作面,实现多点同步施工。本发明根据2#横通道施工进度,可同步实施双连拱隧道进洞；通过保持1#洞超前开挖,提供了水平运输通道；通过增开3-1横通道、3-2横通道和4#横通道,实现多点同步施工,缩短工期,提高施工灵活性；3#洞、4#洞在保持一定步距前提下同步开挖,保证结构稳定性；左线隧道中4#洞保持超前开挖,降低左线隧道爆破开挖对右线隧道已施作完成的衬砌结构的影响。(The invention discloses an asymmetric excavation construction organization method for a double-arch tunnel with an oversized section, which comprises sixteen steps, wherein the double-arch tunnel enters and exits a hole through a transverse channel and a longitudinal channel, and the cooperative construction of the transverse channel and the tunnel entrance is kept; the No. 1 hole is kept to be excavated in advance and is used as a geological pilot hole and a main transportation channel; the multi-point synchronous construction is realized by excavating the pilot tunnel in advance, increasing the transverse channel and simultaneously unfolding a plurality of working faces. According to the construction progress of the No. 2 transverse channel, the double-arch tunnel can be synchronously put into the tunnel; by keeping the 1# tunnel to be excavated in advance, a horizontal transportation channel is provided; by additionally arranging the 3-1 transverse channel, the 3-2 transverse channel and the 4# transverse channel, multipoint synchronous construction is realized, the construction period is shortened, and the construction flexibility is improved; the 3# hole and the 4# hole are synchronously excavated on the premise of keeping a certain step pitch, so that the structural stability is ensured; the 4# hole keeps the advance excavation in the left side line tunnel, reduces the influence of left side line tunnel blasting excavation to the lining structure that the right side line tunnel has executed the work and has accomplished.)

1. An asymmetrical excavation construction organization method for a double arch tunnel with an oversized section is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: excavating into the junction of the double-arch tunnel section (2) and the open excavation section (1) through the C ramp (3);

step two: adopting a step method to excavate a No. 5 temporary channel (4) to reach the end part of the tunnel entrance of the double-arch tunnel to be excavated;

step three: excavating a No. 2 transverse channel (7) by a step method, and constructing a large pipe shed at the opening of the double-arch right-line tunnel (5) after excavating a certain step distance;

step four: after the upper pipe shed of the double-arch right tunnel (5) is finished, excavating a tunnel body of a 1# tunnel upper pilot tunnel (801) and a 2# tunnel lower pilot tunnel (902) and constructing double-layer supporting; excavating a pilot tunnel (901) on the No. 2 tunnel for a certain distance to form three steps and sealing the tunnel face;

step five: downwards excavating the 2# transverse channel (7) to form a 0# hole (11) construction excavation space, excavating the 0# hole (11) in steps and constructing a lining;

step six: continuously excavating the pilot tunnel (801) on the 1# tunnel in advance, obliquely excavating a 3-1 transverse channel (15) to the 0# tunnel (11) by adopting a step method after excavating for a certain distance, increasing the construction working surface of the 0# tunnel (11), and performing reverse landing construction on the 0# tunnel (11);

step seven: after the 0# hole (11) is reversely landed, constructing a hole opening section intermediate wall (20);

step eight: the tunnel entrance end continuously excavates the No. 2 transverse channel (7) rightwards, and a tunnel opening of the double-arch left line (6) is used as a large pipe shed;

step nine: adopting a step method to carry out excavation construction of a pilot tunnel (1001) on a 3# tunnel, keeping an excavation surface of the pilot tunnel (801) on the 1# tunnel and the pilot tunnel (1001) on the 3# tunnel to be ahead of a pilot tunnel (901) on a 2# tunnel by following a double-side wall excavation construction method after the pilot tunnel (1001) on the 3# tunnel advances by a certain step distance, synchronously excavating the pilot tunnel (801) on the 1# tunnel, the pilot tunnel (901) on the 2# tunnel and the pilot tunnel (1001) on the 3# tunnel, and timely constructing an initial support (18), a secondary lining (19) and a tertiary lining (21) on the inner sides of the pilot tunnel (801) on the 1# tunnel, the pilot tunnel (901) on the 2# tunnel and the pilot tunnel (1001) on the 3# tunnel;

step ten: after the construction of the large pipe shed at the opening of the double-arch left line (6) is finished and the pilot tunnel (1001) on the No. 3 tunnel is excavated for a certain distance, sequentially excavating a pilot tunnel (1201) on the No. 4 tunnel, a pilot tunnel (1401) on the No. 6 tunnel and a pilot tunnel (1301) on the No. 5 tunnel, and constructing the primary support (18), the secondary lining (19) and the tertiary lining (21) on the inner sides of the pilot tunnel (1201) on the No. 4 tunnel, the pilot tunnel (1401) on the No. 6 tunnel and the pilot tunnel (1301) on the No. 5 tunnel;

step eleven: after the pilot tunnel (801) on the 1# tunnel is excavated for a certain distance in advance, excavating a 3-2 transverse channel (16) to the 0# tunnel (11), facing the 0# tunnel (11) for excavation, increasing an excavation working surface and providing a transportation channel for the subsequent construction of an intermediate wall (20) in the 0# tunnel (11);

step twelve: excavating a pilot tunnel (802) below the No. 1 tunnel after the No. 2 tunnel upper pilot tunnel (901) is ahead of the 3-1 transverse channel (15), and performing primary support construction of a side wall and an inverted arch of the No. 1 tunnel (8);

step thirteen: breaking the primary support (18) of the 0# hole (11) on the right line, excavating a 3# hole lower pilot tunnel (1002), and performing inverted arch primary support construction on the 3# hole (10);

fourteen steps: excavating the 2# hole lower pilot tunnel (902), carrying out primary inverted arch supporting construction of the 2# hole (9), sealing and looping, then removing the temporary support, and sequentially constructing a right-line three-lining inverted arch, backfilling, three-lining arch part lining and an auxiliary structure;

step fifteen: with reference to the twelfth step to the fourteenth step, excavating a 5# hole lower pilot tunnel (1302), a 6# hole lower pilot tunnel (1402) and a 4# hole lower pilot tunnel (1202) in sequence, performing primary support construction of inverted arches of a 5# hole (13), a 6# hole (14) and a 4# hole (12), sealing and looping, dismantling a temporary support, and constructing a left-line three-lining inverted arch and backfilling, three-lining arch lining and an auxiliary structure in sequence;

sixthly, the steps are as follows: when the 1# tunnel upper pilot tunnel (801) is excavated to the exit end of the double-arch tunnel in advance, the 4# transverse channel (17) is additionally opened, the double-arch tunnel exit construction is met, and the working face of the tunnel entrance end is opposite to the face of the tunnel exit construction.

2. The asymmetric excavation construction organization method for the ultra-large section double arch tunnel according to claim 1, characterized in that: in the fourth step, the pilot tunnel (901) on the No. 2 tunnel is excavated to 15m to form three steps.

3. The asymmetric excavation construction organization method for the ultra-large section double arch tunnel according to claim 1, characterized in that: and in the sixth step, the pilot tunnel (801) on the 1# tunnel is continuously excavated in advance, and the 3-1 transverse channel (15) is obliquely excavated downwards to the 0# tunnel (11) by adopting a step method after the pilot tunnel is excavated for 45 m.

4. The asymmetric excavation construction organization method for the ultra-large section double arch tunnel according to claim 1, characterized in that: and seventhly, constructing the mid-partition (20) with the opening section of 40m after the 0# hole (11) is reversely constructed in a floor-falling mode.

5. The asymmetric excavation construction organization method for the ultra-large section double arch tunnel according to claim 1, characterized in that: in the ninth step, the double-side wall excavation method means that the left and right pilot pits are constructed in advance, and the middle pilot pit is constructed in a lagging mode.

6. The asymmetric excavation construction organization method for the ultra-large section double arch tunnel according to claim 1, characterized in that: in the tenth step, after the pilot tunnel (1001) on the 3# tunnel is excavated for 15m, the pilot tunnel (1201) on the 4# tunnel, the pilot tunnel (1401) on the 6# tunnel and the pilot tunnel (1301) on the 5# tunnel are sequentially excavated, and the excavation process refers to the ninth step and keeps the excavation surfaces of the pilot tunnel (1201) on the 4# tunnel and the pilot tunnel (1401) on the 6# tunnel ahead of the pilot tunnel (1301) on the 5# tunnel.

7. The asymmetric excavation construction organization method for the ultra-large section double arch tunnel according to claim 1, characterized in that: in the eleventh step, after the pilot tunnel (801) on the 1# tunnel is excavated in advance for 100m, the 3-2 transverse channel (16) is excavated to the 0# tunnel (11).

Technical Field

The invention relates to the field of tunnel engineering, in particular to an asymmetric excavation construction organization method for a double arch tunnel with an oversized section.

Background

With the vigorous development of the transportation industry in China, the scale of highway tunnel construction is continuously enlarged, the geological or topographic conditions and the construction environment for tunnel construction are more and more complex, and the construction requirements cannot be met by adopting the traditional separated tunnel due to the limitation of factors such as line connection, overall line shape, engineering cost and the like. The multi-arch tunnel is a novel large-span tunnel structure type provided along with the rapid development of highway tunnels, has the advantages of natural and smooth line shape, high space utilization rate and small occupied area, is difficult to replace in the aspects of reducing the engineering quantity, adapting to line-shaped conditions and protecting the environment, and is widely applied to a plurality of trunk highway tunnels in recent years. According to different surrounding rock conditions, the conventional construction method of the double-arch tunnel mainly comprises a three-pilot-hole construction method, a middle pilot-hole construction method and a double-hole full-section parallel construction method, however, no matter which construction method is adopted, a plurality of working faces are difficult to expand, the construction space is extremely limited, and the double-arch tunnel is low in construction efficiency, long in construction period and poor in flexibility.

Disclosure of Invention

The invention aims to provide an asymmetric excavation construction organization method for a double arch tunnel with an oversized section, which solves the problem that how to unfold the double arch tunnel to enter or exit under the condition that the tunnel cannot enter from the front; how to expand a plurality of working faces in the excavation process of the double-arch tunnel body to realize multipoint synchronous construction; the problem how to ensure smooth transportation of materials and muck under the condition of synchronous construction of a plurality of working faces.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention discloses an asymmetric excavation construction organization method for an oversized section double-arch tunnel, which comprises the following steps:

the method comprises the following steps: excavating through a C ramp to enter the junction of the double-arch tunnel section and the open excavation section;

step two: adopting a step method to excavate a No. 5 temporary channel to reach the end part of the double-arch tunnel to be excavated;

step three: excavating a No. 2 transverse channel by a step method, and constructing a large pipe shed at the opening of the double-arch right-line tunnel after excavating a certain step distance;

step four: after the upper pipe shed of the double-arch right-line tunnel is finished, carrying out the excavation of the upper pilot tunnel of the No. 1 tunnel, the lower pilot tunnel body of the No. 2 tunnel and double-layer supporting construction; excavating a pilot tunnel on the No. 2 tunnel for a certain distance to form three steps and sealing the tunnel face;

step five: downwards excavating the No. 2 transverse channel to form a No. 0 hole construction excavation space, excavating the No. 0 hole in steps and constructing a lining;

step six: continuously and in advance excavating the pilot tunnel on the 1# tunnel, obliquely downwards excavating a 3-1 transverse channel to the 0# tunnel by adopting a step method after excavating for a certain distance, increasing the construction working surface of the 0# tunnel, and performing reverse landing construction on the 0# tunnel;

step seven: after the 0# hole is reversely landed, constructing a hole opening section intermediate wall;

step eight: the tunnel entrance end continuously excavates the No. 2 transverse channel rightwards, and a tunnel opening of the double-arch left line is used as a large pipe shed;

step nine: adopting a step method to carry out pilot tunnel excavation construction on a 3# tunnel, keeping the pilot tunnel on the 1# tunnel and the pilot tunnel excavation surface on the 3# tunnel ahead of the pilot tunnel on the 2# tunnel by following a double-side-wall excavation construction method after the pilot tunnel on the 3# tunnel advances by a certain step distance, synchronously excavating the pilot tunnel on the 1# tunnel, the pilot tunnel on the 2# tunnel and the pilot tunnel on the 3# tunnel, and timely constructing the inner sides of the pilot tunnel on the 1# tunnel, the pilot tunnel on the 2# tunnel and the pilot tunnel on the 3# tunnel as an initial support, a second lining and a third lining;

step ten: after the construction of the large pipe shed at the opening of the double-arch left line is finished and the pilot tunnel on the No. 3 tunnel is excavated for a certain distance, sequentially excavating a pilot tunnel on the No. 4 tunnel, a pilot tunnel on the No. 6 tunnel and a pilot tunnel on the No. 5 tunnel, and constructing the primary support, the secondary lining and the tertiary lining on the inner sides of the pilot tunnel on the No. 4 tunnel, the pilot tunnel on the No. 6 tunnel and the pilot tunnel on the No. 5 tunnel;

step eleven: after the pilot tunnel on the No. 1 tunnel is excavated for a certain distance in advance, excavating a 3-2 transverse channel to the No. 0 tunnel, facing the excavation of the No. 0 tunnel, increasing an excavation working surface and providing a transportation channel for the subsequent construction of the intermediate wall in the No. 0 tunnel;

step twelve: excavating the upper pilot tunnel of the No. 2 tunnel ahead of the 3-1 transverse channel, excavating the lower pilot tunnel of the No. 1 tunnel, and performing primary support construction on side walls and inverted arches of the No. 1 tunnel;

step thirteen: breaking the primary support of the 0# hole on the right line, excavating a pilot tunnel under the 3# hole, and performing primary support construction of an inverted arch of the 3# hole;

fourteen steps: excavating the lower pilot tunnel of the No. 2 tunnel, carrying out primary support construction of an inverted arch of the No. 2 tunnel, removing a temporary support after sealing and looping, and sequentially constructing a right-line three-lining inverted arch, backfilling, a three-lining arch part lining and an auxiliary structure;

step fifteen: referring to the twelfth step and the fourteenth step, excavating a pilot tunnel under a 5# tunnel, a pilot tunnel under a 6# tunnel and a pilot tunnel under a 4# tunnel in sequence, carrying out primary support construction on inverted arches of the 5# tunnel, the 6# tunnel and the 4# tunnel, removing temporary supports after sealing and looping, and constructing a left-line three-lining inverted arch and backfilling, and lining and an auxiliary structure of a three-lining arch part in sequence;

sixthly, the steps are as follows: and when the pilot tunnel on the 1# tunnel is excavated to the exit end of the double arch tunnel in advance, the 4# cross channel is additionally opened, the double arch tunnel exits the tunnel construction in a head-on mode, and the head-on construction is performed with the operation surface of the entrance end.

Further, in the fourth step, the pilot tunnel on the # 2 tunnel is excavated to 15m to form three steps.

And further, in the sixth step, the pilot tunnel on the 1# tunnel is continuously excavated in advance, and the 3-1 transverse channel is obliquely excavated downwards to the 0# tunnel by adopting a step method after excavating for 45 m.

And further, in the seventh step, after the 0# hole is reversely landed, constructing the intermediate wall with a hole opening section of 40 m.

Furthermore, in the ninth step, the double-side wall excavation method means that the left and right heading is performed first, and the middle heading is performed later.

Furthermore, in the tenth step, after the pilot tunnel on the 3# tunnel is excavated for 15m, the pilot tunnel on the 4# tunnel, the pilot tunnel on the 6# tunnel, and the pilot tunnel on the 5# tunnel are excavated in sequence, and the excavation process refers to the ninth step and keeps the excavation surfaces of the pilot tunnel on the 4# tunnel and the pilot tunnel on the 6# tunnel ahead of the pilot tunnel on the 5# tunnel.

Further, in the eleventh step, after the pilot tunnel on the 1# tunnel is excavated in advance for 100m, the 3-2 transverse channel is excavated to the 0# tunnel.

Compared with the prior art, the invention has the beneficial technical effects that:

the invention relates to an asymmetric excavation construction organization method of an oversized section double-arch tunnel, which comprises the sixteen steps, and the double-arch tunnel can be synchronously tunneled according to the construction progress of a No. 2 cross channel, so that the construction period is effectively shortened; by keeping the advanced excavation of the No. 1 tunnel, a horizontal transportation channel is provided, the smooth transportation of materials and muck is ensured, the construction efficiency is improved, meanwhile, the conditions of front geology, pipelines, barriers and the like can be judged in advance, and the construction scheme is convenient to adjust in time; by additionally arranging the 3-1 transverse channel, the 3-2 transverse channel and the 4# transverse channel, the construction working surface is increased, multi-point synchronous construction is realized, the construction period is effectively shortened, and the construction flexibility is improved; in the construction process of the 3# tunnel and the 4# tunnel, synchronous excavation is carried out on the premise of keeping a certain step distance, so that the bias stress condition of the intermediate wall is improved to the maximum extent, and the structural stability of the double arch tunnel is ensured; the 4# hole in the left tunnel is kept to be excavated in advance, and a free face is formed between the right tunnel and the left tunnel, so that the influence of blasting excavation of the left tunnel on the constructed lining structure of the right tunnel can be greatly reduced; the invention expands the double arch tunnel to enter and exit the tunnel through the transverse and longitudinal channels, and keeps the cooperative construction of the transverse channel and the tunnel to enter the tunnel; the No. 1 hole is kept to be excavated in advance and is used as a geological pilot hole and a main transportation channel; the multi-point synchronous construction is realized by excavating the pilot tunnel in advance, increasing the transverse channel and simultaneously unfolding a plurality of working faces.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 is a first plan view of a double arch tunnel according to the present invention;

FIG. 2 is a second plan view of a double arch tunnel of the present invention;

FIG. 3 is a cross-sectional view of a double arch tunnel of the present invention;

FIG. 4 is a view showing the construction steps of the present invention;

description of reference numerals: 1. an open cut section; 2. a double arch tunnel segment; 3. c, ramp; 4. 5# auxiliary channel; 5. a double-arch right tunnel; 6. a double-arch left-line tunnel; 7. 2# transverse channel; 8. 1# hole; 801. a pilot hole is arranged on the No. 1 hole; 802. leading a tunnel under the No. 1 tunnel; 9. a No. 2 hole; 901. a 2# hole is provided with a pilot hole; 902. leading a tunnel under the No. 2 tunnel; 10. a No. 3 hole; 1001. a pilot hole is arranged on the No. 3 hole; 1002. 3, guiding a hole below the # hole; 11. a # 0 hole; 12. a No. 4 hole; 1201. a 4# hole is provided with a pilot hole; 1202. leading a tunnel under the No. 4 tunnel; 13. a No. 5 hole; 1301. a 5# hole is provided with a pilot hole; 1302. leading a tunnel below the No. 5 tunnel; 14. a No. 6 hole; 1401. a 6# hole is provided with a pilot hole; 1402. leading a tunnel under the No. 6 tunnel; 15. 3-1 transverse channel; 16. 3-2 transverse channels; 17. 4# transverse channel; 18. primary support; 19. a second liner; 20. an intermediate wall; 21. and (4) three linings.

Detailed Description

As shown in fig. 1-4, a method for constructing an asymmetrical excavation structure of a double arch tunnel with an oversized cross section comprises the following steps:

the method comprises the following steps: excavating into the junction of the double-arch tunnel section 2 and the open excavation section 1 through the C ramp 3;

step two: adopting a step method to excavate a No. 5 temporary channel 4 to reach the end part of the double-arch tunnel to be excavated;

step three: excavating a No. 2 transverse channel 7 by a step method, and constructing a large pipe shed at the opening of the double-arch right-line tunnel 5 after excavating a certain step distance;

step four: after the pipe shed at the upper part of the double-arch right tunnel 5 is finished, excavating the tunnel body of the upper pilot tunnel 801 of the No. 1 tunnel and the lower pilot tunnel 902 of the No. 2 tunnel and constructing double-layer support; excavating a pilot tunnel 901 on the No. 2 tunnel to 15m to form three steps and sealing the tunnel face;

step five: downwards excavating the No. 2 transverse channel 7 to form a No. 0 hole 11 construction excavation space, excavating the No. 0 hole 11 in steps and constructing a lining;

step six: continuously excavating the pilot tunnel 801 on the # 1 tunnel in advance, obliquely excavating the 3-1 transverse channel 15 downwards to the # 0 tunnel 11 by adopting a step method after excavating for 45m, adding the construction working surface of the # 0 tunnel 11, and performing reverse landing construction on the # 0 tunnel 11;

step seven: after the 0# hole 11 is reversely landed, constructing a middle partition wall 20 with a hole section of 40 m;

step eight: the tunnel entrance end continuously excavates the No. 2 transverse channel 7 rightwards, and a tunnel opening of the double-arch left line 6 is constructed as a large pipe shed; according to the construction progress of the No. 2 transverse channel 7, double-arch tunnel entering can be synchronously implemented, and the construction period is effectively shortened;

step nine: adopting a step method to carry out excavation construction of a pilot tunnel 1001 on a 3# tunnel, keeping the excavation surface of the pilot tunnel 1001 on the 3# tunnel ahead of a pilot tunnel 901 on a 2# tunnel by following a double-side wall excavation construction method after the pilot tunnel 1001 on the 3# tunnel advances by a certain step distance, synchronously excavating the pilot tunnel 801 on the 1# tunnel, the pilot tunnel 901 on the 2# tunnel and the pilot tunnel 1001 on the 3# tunnel, and timely constructing an initial support 18, a secondary lining 19 and a tertiary lining 21 on the inner sides of the pilot tunnel 801 on the 1# tunnel, the pilot tunnel 901 on the 2# tunnel and the pilot tunnel 1001 on the 3# tunnel;

step ten: after the construction of the large pipe shed at the opening of the double-arch left line 6 is finished and the pilot tunnel 1001 on the No. 3 tunnel is excavated for 15m, sequentially excavating a pilot tunnel 1201 on the No. 4 tunnel, a pilot tunnel 1401 on the No. 6 tunnel and a pilot tunnel 1301 on the No. 5 tunnel, and constructing the primary support 18, the secondary lining 19 and the tertiary lining 21 on the inner sides of the pilot tunnel 1201 on the No. 4 tunnel, the pilot tunnel 1401 on the No. 6 tunnel and the pilot tunnel 1301 on the No. 5 tunnel;

step eleven: after the pilot tunnel 801 on the 1# tunnel is excavated for 100m in advance, excavating a 3-2 transverse channel 16 to the 0# tunnel 11, facing the 0# tunnel 11 for excavation, increasing an excavation working surface, and providing a transportation channel for the subsequent construction of the intermediate wall 20 in the 0# tunnel 11;

step twelve: excavating a 2# tunnel upper pilot tunnel 901 ahead of the 3-1 transverse channel 15, excavating a 1# tunnel lower pilot tunnel 802, and performing primary support construction of 8 side walls and an inverted arch of the 1# tunnel;

step thirteen: breaking the primary support 18 of the No. 0 hole 11 on the right line, excavating a No. 3 hole lower pilot tunnel 1002, and performing inverted arch primary support construction on the No. 3 hole 10;

fourteen steps: excavating the 2# hole lower pilot tunnel 902, performing 2# hole 9 inverted arch primary support construction, sealing to form a ring, removing a temporary support, and sequentially constructing a right-line three-lining inverted arch, backfilling, three-lining arch part lining and an auxiliary structure;

step fifteen: with reference to the twelfth step to the fourteenth step, the excavation of a pilot tunnel 1302 under a 5# tunnel, a pilot tunnel 1402 under a 6# tunnel and a pilot tunnel 1202 under a 4# tunnel is sequentially completed, the preliminary supporting construction of inverted arches of a 5# tunnel 13, a 6# tunnel 14 and a 4# tunnel 12 is carried out, after the preliminary supporting construction is closed and looped, temporary supports are removed, and a left-line three-lining inverted arch, backfilling and three-lining arch lining and an auxiliary structure are sequentially constructed; in the construction process of the 3# tunnel 10 and the 4# tunnel 12, synchronous excavation is carried out on the premise of keeping a certain step distance, so that the bias stress condition of the intermediate wall is improved to the maximum extent, and the structural stability of the double arch tunnel is ensured; the No. 4 tunnel 12 in the left tunnel is kept to be excavated in advance, and a free face is formed between the right tunnel and the left tunnel, so that the influence of blasting excavation of the left tunnel on the finished lining structure of the right tunnel can be greatly reduced;

sixthly, the steps are as follows: when the pilot tunnel 801 on the 1# tunnel is excavated to the exit end of the double arch tunnel in advance, the 4# transverse channel 17 is additionally opened, the exit construction of the double arch tunnel is met, and the pilot tunnel is opposite to the operation surface at the entrance end; by keeping the advanced excavation of the No. 1 tunnel 8, a horizontal transportation channel is provided, the smooth transportation of materials and muck is ensured, the construction efficiency is improved, meanwhile, the conditions of front geology, pipelines, barriers and the like can be judged in advance, and the construction scheme is convenient to adjust in time; by additionally arranging the 3-1 transverse channel, the 3-2 transverse channel and the 4# transverse channel, the construction working surface is increased, multi-point synchronous construction is realized, the construction period is effectively shortened, and the construction flexibility is improved; .

Specifically, in the ninth step, the double-side wall excavation method is a method in which the left and right heading is preceded and the middle heading is delayed.

In the tenth step, the excavation process refers to the ninth step and keeps the excavation surfaces of the top pilot tunnel 1201 of the 4# tunnel and the top pilot tunnel 1401 of the 6# tunnel ahead of the top pilot tunnel 1301 of the 5# tunnel.

The method of the invention overcomes the following problems through the specific construction steps:

1. under the condition that the front face of the tunnel cannot enter the tunnel, how to unfold the double arch tunnel to enter and exit the tunnel;

2. how to expand a plurality of working faces in the excavation process of the double-arch tunnel body to realize multipoint synchronous construction;

3. under the condition of synchronous construction of a plurality of working faces, how to ensure smooth transportation of materials and muck.

The invention opens the double arch tunnel to enter and exit through the transverse and longitudinal channels, keeps the cooperative construction of the transverse channel and the tunnel to enter and exit, and is protected; keeping advanced excavation through a No. 1 tunnel to serve as a geological pilot tunnel and a main transportation channel; the multi-point synchronous construction is realized by excavating the pilot tunnel in advance, increasing the transverse channel and simultaneously unfolding a plurality of working faces, and the protection is required.

According to the invention, a plurality of working surfaces are unfolded in the excavation process of the tunnel body of the double arch tunnel, so that multipoint synchronous construction is realized; under the condition of synchronous construction of a plurality of working faces, smooth transportation of materials and muck is ensured.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.