A construction method for a mountain shed tunnel

Abstract

The present invention provides a construction method for a mountainside shed tunnel, comprising: constructing a concealed excavation section and an open section according to a mountain slope 1 to form a single-arch single-span structure whose span direction is parallel to a preset driving direction; constructing multiple single-arch single-span structures to form a continuous arch structure; connecting the continuous arch structures to form a mountainside shed tunnel, so that the span length and the number of continuous arch structure groups can be flexibly adjusted according to strength requirements. At the same time, during the construction process, since the construction excavation direction is perpendicular to the driving direction, the construction safety is strong, the number of construction working surfaces that can be excavated at the same time is increased, and the construction efficiency of the shed tunnel is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering, and in particular to a construction method of a mountainside shed tunnel. Background Art

[0002] A shed tunnel is a special type of tunnel, which is an open tunnel structure that is not completely closed. One side of the shed tunnel structure is against the mountain and the other side is open to the sky. The side against the mountain is a protective wall attached to the wall, and the side facing the sky is a column, frame or arched window. The top is closed and backfilled with soil and rocks to form a semi-shelter structure. Shed tunnels are often used in tunnel oblique entrance sections or road sections along rivers and mountains, with steep slopes, etc. They are shed structures set up to conform to the terrain, protect the environment, reduce slope excavation, and protect the safety of people and vehicles in sections prone to geological disasters such as landslides and falling rocks. Taking the more common outer column flat-top inner arch wall or rectangular shed tunnels in road engineering as an example, the following two construction methods are generally required:

[0003] (1) Open cut and backfill method

[0004] like Figure 1 As shown, the construction sequence of the open cut and backfill method is: excavate the mountain to form a temporary slope surface; build the pile foundation on the air side of the shed tunnel structure or expand the foundation and the bottom longitudinal beam between the columns; build the retaining wall on the air side of the shed tunnel structure and backfill under the bottom plate; construct the bottom plate, outer columns, side walls on the side facing the mountain, top plate and retaining walls above the top plate of the shed tunnel structure to form an integral structure; build the internal roadbed and pavement of the shed tunnel, drainage pipes, curbstone anti-collision, maintenance trails and other ancillary structures; backfill the soil and stone above the top plate of the shed tunnel structure and green the slope. The mountainside tunnel built by the open-cut and backfill method is a cast-in-place reinforced concrete frame structure, which has strong integrity, clear force, simple process and mature technology; but it also has significant disadvantages: this structural construction method requires excavation of the original mountain to open up construction space for building the tunnel structure. The artificial excavation slope formed is a large-scale high and steep slope, which is contrary to the original intention of using a tunnel to minimize the slope excavation range, reduce the slope excavation height, and protect the natural vegetation and environmental features.

[0005] (ii) Half-light and half-dark method

[0006] The semi-open and semi-hidden method is to construct a mountain-side tunnel with half section open and half section dark excavation, such as Figure 2As shown, the construction sequence is as follows: select a reasonable position according to the terrain to determine the cross-section open and dark excavation dividing slope, clean the surface, and form a temporary slope surface through artificial excavation; install locking anchor rods or anchor cables to stabilize the mountain; build the pile foundation of the exposed part of the shed-hole structure or expand the foundation and the bottom longitudinal beam between the columns; build the retaining wall of the exposed part of the shed-hole structure and backfill under the bottom plate; construct the arched bottom plate of the exposed part of the shed-hole structure; build the outer columns of the exposed part of the shed-hole structure; erect temporary supporting columns; build the exposed part of the shed-hole structure The flat top plate of the part is constructed; the advanced large pipe shed support of the dark excavation part of the shed tunnel structure is constructed; the rock and soil of the dark excavation part of the shed tunnel structure is excavated, and the anchor rods of the system around the tunnel and the initial support arch side wall and arch bottom plate in the composite lining of the dark excavation part of the shed tunnel structure are constructed as the excavation progresses; the secondary lining arch side wall and arch bottom plate in the composite lining of the dark excavation part of the shed tunnel structure are constructed; the substructures such as the roadbed and pavement, drainage pipe trench, curbstone anti-collision, and inspection trail inside the shed tunnel structure are constructed; the soil and stone above the top plate of the shed tunnel structure and the green slope are backfilled. The mountain-side shed tunnel constructed by the semi-open and semi-dark method is a combination of the cast-in-place reinforced concrete structure of the open part and the composite lining structure of the dark excavation part, forming an integral structure with a flat roof of the outer column and an arch wall inside. This structure and construction method are the structural forms and construction methods with many application cases of existing technical solutions. The technology is relatively mature and the structural integrity is good. Its biggest advantage is that since the tunnel structure is located below the mountain and the dark excavation method is used for construction, the excavation of the original natural terrain slope of the mountain is avoided, and the natural vegetation and environmental features of the proposed shed tunnel section are effectively protected; but the biggest disadvantage is that the construction risk is high. Due to the special location of the road along the mountain, the excavation of the dark excavation part of the shed tunnel structure is a great destruction and disturbance to the stability of the half-cut slope foot of the natural mountain. The natural mountain or covering layer at the location of the proposed route is thick, the soil and stone and other slope deposits are loose, or the rock mass is highly weathered and the joints and fissures are developed. There are risks such as slope instability, bias, rockfall, collapse, and large deformation for the construction of the dark excavation part. When the cross-sectional span of the tunnel is large, there are still shortcomings such as insufficient structural bearing capacity and large amount of support and reinforcement measures invested to stabilize the slope and surrounding rock, poor economy, low construction efficiency, and long construction period.

[0007] Therefore, there is an urgent need to provide an improved construction method for mountain shed tunnels that can solve the problems of high construction risk, long construction period and insufficient structural bearing capacity in the prior art. Summary of the invention

[0008] The present invention aims to provide a construction method for a mountain shed tunnel, which can solve the above-mentioned technical problems.

[0009] According to one aspect of the present invention, a method for constructing a mountainside shed tunnel is provided, comprising: constructing a concealed excavation section and an open excavation section according to a mountain slope 1 to form a single-arch single-span structure whose span direction is parallel to a preset driving direction; constructing multiple single-arch single-span structures to form a continuous arch structure; and connecting the continuous arch structures to form a mountainside shed tunnel.

[0010] Preferably, constructing a concealed excavation section and an open section according to the mountain slope 1 to form a single-arch single-span structure with a span direction parallel to the preset driving direction includes: determining the boundary position of the concealed excavation section and the open section according to the mountain slope 1; constructing the structure of the upper half section of the concealed excavation section of the single-arch single-span structure; constructing the structure of the open section of the single-arch single-span structure; and constructing the structure of the lower half section of the concealed excavation section of the single-arch single-span structure.

[0011] Preferably, the structure of the upper section of the dark excavation section with a single-arch single-span structure includes: providing support for the upper guide tunnel of the dark excavation section; providing a dark excavation section support beam 5-1 through the bottom surface of the upper guide tunnel of the dark excavation section in a direction perpendicular to the driving direction, wherein the distance between two adjacent dark excavation section support beams 5-1 is equal to the designed span of the single-arch single-span structure; providing support for the upper section of the dark excavation section according to the structure of the upper guide tunnel of the dark excavation section; and providing the main structure of the upper section of the dark excavation section.

[0012] Preferably, the support for the upper guide tunnel of the dark excavation section includes: constructing an advance support 2-1 of a large pipe shed for the upper guide tunnel of the dark excavation section outside the excavation contour line of the upper guide tunnel of the dark excavation section, and arranging it in a direction perpendicular to the driving direction; constructing an anchor rod 2-2 for the upper guide tunnel of the dark excavation section as the paving surface of the upper guide tunnel of the dark excavation section advances, and the anchor rod 2-2 for the upper guide tunnel of the dark excavation section is arranged around the upper guide tunnel of the dark excavation section; constructing an initial support 3-1 for the upper guide tunnel of the dark excavation section as the paving surface of the upper guide tunnel of the dark excavation section advances, and the initial support 3-1 is composed of a steel grating arch frame or a steel arch frame and a shotcrete support, and the steel grating arch frame or the steel arch frame is attached to the inner wall of the upper guide tunnel of the dark excavation section, and the shotcrete support covers the steel grating arch frame or the steel arch frame.

[0013] Preferably, according to the structure of the upper guide tunnel of the dark excavation section, the support of the upper half section of the dark excavation section includes: determining the remaining contour line of the upper half section of the dark excavation section according to the non-intersecting part of the excavation contour line of the upper half section of the dark excavation section and the excavation contour line of the upper guide tunnel of the dark excavation section; removing the structure of the large pipe shed advance support 2-1 of the upper guide tunnel of the dark excavation section and the anchor rod 2-2 of the upper guide tunnel system of the dark excavation section located inside the upper half section of the dark excavation section; and constructing the large pipe shed advance support 2-3 of the upper half section of the dark excavation section outside the remaining contour line, arranged in the vertical direction of the driving direction; As the mortar surface of the upper section of the dark excavation section advances, the system anchor rods 2-4 of the upper section of the dark excavation section are installed. The system anchor rods 2-4 of the upper section of the dark excavation section are only arranged in the remaining contour line area around the hole of the upper section of the dark excavation section; as the mortar surface of the upper section of the dark excavation section advances, the initial support 3-2 of the upper section of the dark excavation section is installed, which is composed of a steel grating arch frame or a steel arch frame and a shotcrete support. The steel grating arch frame or the steel arch frame is attached to the inner wall of the upper section of the dark excavation section, and the shotcrete support covers the steel grating arch frame or the steel arch frame.

[0014] Preferably, the main structure of the upper section of the dark excavation section includes: a secondary lining structure 4-1 of the upper section of the dark excavation section is constructed along the inner wall of the initial support 3-2 of the upper section of the dark excavation section, which together with the initial support 3-2 of the upper section of the dark excavation section forms a dark excavation section vault, and the lower end of the secondary lining structure 4-1 of the upper section of the dark excavation section is connected with the dark excavation section support beam 5-1, so that the cross-sections of multiple adjacent dark excavation section vaults present a continuous arch shape; the upper half part 6-1 of the dark excavation section end wall and the middle longitudinal beam 8-1 of the dark excavation section are constructed along the end face of the mountain side of the upper section of the dark excavation section, and the middle longitudinal beam 8-1 of the dark excavation section is located at the bottom of the upper half part 6-1 of the end wall and connected between two adjacent dark excavation section support beams 5-1.

[0015] Preferably, the construction of the single-arch single-span open-type structure includes: according to the terrain and geological conditions of the open-type section, determining the pile foundation or the expanded foundation as the foundation form of the open-type section column 7-2; when the pile foundation is selected, the open-type section column 7-2 is supported on the open-type section pile foundation 7-4 through the open-type section column bottom bearing platform 7-3; when the expanded foundation is selected, the open-type section column 7-2 is directly supported on the open-type section expanded foundation; according to the determined foundation form, a slab is constructed on the air-facing side of the mountain slope 1. The exposed section columns 7-2, the bottom caps 7-3 of the two adjacent exposed section columns or the exposed section enlarged foundations are connected with the bottom longitudinal beams 8-3 between the exposed section columns; the exposed section support beams 5-2 are constructed, connected with the dark excavation section support beams 5-1 to form a whole, and one end of the exposed section support beams 5-2 facing the air side is supported on the exposed section columns 7-2; the exposed section vault 4-2 is constructed above the exposed section support beams 5-2, connected with the secondary lining structure 4-1 of the upper half section of the dark excavation section to form an integral vault.

[0016] Preferably, the structure of the lower half section of the dark excavation section with a single-arch single-span structure includes: clearing the mountain to align the excavation contour line of the lower guide tunnel of the dark excavation section with the excavation contour line of the upper guide tunnel of the dark excavation section; supporting the lower guide tunnel of the dark excavation section; casting a dark excavation section bottom longitudinal beam 8-2 connected to the two side walls of the lower guide tunnel of the dark excavation section at the bottom of the end face on the mountain side of the lower guide tunnel of the dark excavation section; casting a dark excavation section wall-attached column 7-1 at the end face on the mountain side of the lower guide tunnel of the dark excavation section, the bottom of the dark excavation section wall-attached column 7-1 is vertically connected to the dark excavation section bottom longitudinal beam 8-2, and the top of the dark excavation section wall-attached column 7-1 supports the dark excavation section support beam 5-1; removing the support of the lower guide tunnel of the dark excavation section, and constructing the lower half of the dark excavation section end wall 6-2 along the end face on the mountain side of the lower half section of the dark excavation section, and the lower half of the dark excavation section end wall 6-2 is connected to two adjacent dark excavation section wall-attached columns 7-1.

[0017] Preferably, the support for the lower guide tunnel of the dark excavation section includes: constructing anchor rods 2-5 of the lower guide tunnel system of the dark excavation section as the paving surface of the lower guide tunnel of the dark excavation section advances, and the anchor rods 2-5 of the lower guide tunnel system of the dark excavation section are arranged on the side walls of the lower guide tunnel of the dark excavation section; constructing initial support 3-3 for the lower guide tunnel of the dark excavation section as the paving surface of the lower guide tunnel of the dark excavation section advances, which is composed of a steel grating arch frame or a steel arch frame and a shotcrete support, and the steel grating arch frame or the steel arch frame is attached to the inner wall of the lower guide tunnel of the dark excavation section, and the shotcrete support covers the steel grating arch frame or the steel arch frame.

[0018] Preferably, connecting the continuous arch structures to form a mountain-side shed tunnel includes: connecting multiple bottom longitudinal beams 8-2 of dark-cut sections along the driving direction; filling the roadbed backfill 9-2 below the road surface base of the proposed open-work section road, and when pile foundations are used, an open-work section pile retaining wall 9-1 for supporting the roadbed backfill 9-2 is arranged between two adjacent open-work section pile foundations 7-4; arranging an air-facing side retaining wall 9-3 above the open-work section arch 4-2 along the driving direction to support the mountain slope 1, the air-facing side retaining wall 9-3 and the arch backfill 11 between the arch enclosed area; constructing the internal roadbed and pavement, drainage pipes and ditches, curb collision prevention, maintenance trails and other auxiliary structures 10 of the tunnel; when multiple sets of continuous arch structures are arranged continuously, a deformation joint is arranged between two adjacent sets of continuous arch structures.

[0019] The present invention provides a construction method for a mountainside shed tunnel, comprising: constructing a concealed excavation section and an open section according to a mountain slope 1 to form a single-arch single-span structure whose span direction is parallel to a preset driving direction; constructing multiple single-arch single-span structures to form a continuous arch structure; connecting the continuous arch structures to form a mountainside shed tunnel, so that the span length and the number of continuous arch structure groups can be flexibly adjusted according to the bearing capacity requirements. At the same time, during the construction process, since the construction excavation direction is perpendicular to the driving direction, the construction safety is strong, the number of construction working surfaces that can be excavated at the same time is increased, and the construction efficiency of the shed tunnel is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 It is a structural schematic diagram of a shed tunnel using the open cut and backfill method according to the prior art;

[0022] Figure 2 It is a schematic diagram of the structure of a shed tunnel using a semi-bright and semi-dark method according to the prior art;

[0023] Figure 3 is a schematic diagram of the three-dimensional structure of a mountain shed tunnel according to an embodiment of the present invention;

[0024] FIG4 is a schematic diagram of the construction process of a mountain shed tunnel according to an embodiment of the present invention;

[0025] Among them, 1. Mountain slope; 2-1. Advance support of large pipe shed for upper pilot tunnel in dark excavation section; 2-2. System anchor rod for upper pilot tunnel in dark excavation section; 2-3. Advance support of large pipe shed for arch in dark excavation section; 2-4. System anchor rod for upper half section of dark excavation section; 2-5. System anchor rod for lower pilot tunnel in dark excavation section; 3-1. Initial support for upper pilot tunnel in dark excavation section; 3-2. Initial support for upper half section of dark excavation section; 3-3. Initial support for lower pilot tunnel in dark excavation section; 4-1. Secondary lining structure for upper half section of dark excavation section; 4-2. Arch in open section; 5-1. Support beam in dark excavation section; 5-2. Support beam in open section; 6-1. -1. The upper part of the end wall; 6-2. The lower part of the end wall; 7-1. The wall columns of the concealed section; 7-2. The columns of the exposed section; 7-3. The bottom pedestal of the columns of the exposed section; 7-4. The pile foundation of the exposed section; 8-1. The middle longitudinal beam of the concealed section; 8-2. The bottom longitudinal beam of the concealed section; 8-3. The bottom longitudinal beam between the columns of the exposed section; 9-1. The retaining wall between the piles of the exposed section; 9-2. The backfill under the roadbed; 9-3. The retaining wall on the side facing the air; 10. The roadbed and pavement, drainage pipe ditch, curb collision prevention, maintenance walkway and other ancillary structures inside the tunnel; 11. The backfill of the arch; 12. The construction limit of the proposed road. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] Reference will now be made in detail to various embodiments of the present invention, examples of which are shown in the accompanying drawings and described below. For ease of interpretation and precise definition in the appended claims, the terms "upper", "lower", "inner" and "outer" are used to describe features of the exemplary embodiments shown in the drawings with reference to their positions.

[0028] Figure 3 4 and 5 respectively show a schematic diagram of the three-dimensional structure and a schematic diagram of the construction process of a mountainside shed tunnel according to an embodiment of the present invention. As shown in the figure, the mountainside shed tunnel construction method includes: constructing a concealed excavation section and an open section according to a mountain slope 1 to form a single-arch single-span structure whose span direction is parallel to a preset driving direction; constructing multiple single-arch single-span structures to form a continuous arch structure; connecting the continuous arch structures to form a mountainside shed tunnel.

[0029] According to an embodiment of the present invention, a concealed excavation section and an open section are constructed according to a mountain slope 1 to form a single-arch single-span structure whose span direction is parallel to a preset driving direction, including: determining the boundary position of the concealed excavation section and the open section according to the mountain slope 1; constructing the structure of the upper half section of the concealed excavation section of the single-arch single-span structure; constructing the structure of the open section of the single-arch single-span structure; and constructing the structure of the lower half section of the concealed excavation section of the single-arch single-span structure.

[0030] In the related art, the shed tunnel is constructed by open-cut backfill method or semi-open and semi-dark method to form a mountainside shed tunnel with a flat roof and an inner arch wall or a rectangular cross-section. However, when the width of the proposed road surface is large, the tunnel structure formed by this construction method has poor stability, and faces great safety risks and long construction period during the construction process. Different from the related art in which the span direction of the shed tunnel is perpendicular to the driving direction, the mountainside shed tunnel of the embodiment of the present invention arranges one or more groups of serially connected arch structures along the driving direction, and each group of arch structures is connected by a number of single-arch single-span structures with spans parallel to the driving direction. It can improve the stress condition of the mountainside shed tunnel structure, reduce the construction risk of the mountainside shed tunnel structure, avoid large-scale cutting of the mountain when building the shed tunnel, maintain the stability of the natural slope, and protect the natural environment and ecological landscape. During the specific construction process, the span of the single-arch single-span structure of the embodiment of the present invention can be flexibly determined according to the rationality and economy of the structural stress; the number of holes (i.e., the number of spans) of each group of continuous arch structures is determined after structural stress analysis, and can generally be 3 continuous arches or 5 continuous arches or more; the number of groups of continuous arch structures is determined according to the terrain, geology, and route design conditions, that is, the length of the road section to be protected. When the geological conditions or slope stability are poor, the span can be reduced to reduce the load borne by the single-arch single-span structure and the continuous arch structure, so as to achieve the purpose of improving the structural stress conditions, improving the cross-sectional economy, and reducing the construction risk. The construction method of the mountain-side shed tunnel of the embodiment of the present invention can form multiple adjacent, parallel, coordinated, but mutually less interfering construction working surfaces, get rid of the constraints of the existing technical solution that there are only two construction working surfaces at the inlet and outlet ends along the longitudinal direction of the proposed road, and can further speed up the construction progress; at the same time, each single-arch single-span structure and continuous arch structure has the same cross-section, the same excavation method, and the same structural construction method, which has good construction consistency, is conducive to forming standardized construction, and is conducive to carrying out circulating flow operations.

[0031] In addition, in the related art, the shed tunnel structure is divided into an open part and a dark excavation part in the cross section. In the embodiment of the present invention, each single-arch single-span structure is divided into an open section and a dark excavation section along its longitudinal direction (with the driving direction as the transverse direction). The arch and support beam of each single-arch single-span structure are longitudinally connected (with the driving direction as the transverse direction), and are connected to the columns on both sides as a whole. They are the main load-bearing components that bear the overlying load. Compared with the traditional shed tunnel structure, the force is more uniform, and the modular property of the structure is stronger, which is convenient for the simultaneous construction of multiple single-arch single-span structures and shortens the construction time. The distribution range of multiple groups of serially connected arch structures in the embodiment of the present invention along the driving direction covers the length of the proposed mountainside road that needs to be protected, that is, the length of the mountainside shed tunnel. When the distribution range of the arch structure along the driving direction remains unchanged, reducing the span of the single-arch single-span structure means that the number of holes in the single-arch single-span structure increases accordingly, and at the same time, the number of common support beams at the arch foot of each arch is also increased accordingly, which is conducive to reducing the load distributed to the common support beam and improving its stress state. The span of the support beam is the cross-sectional width of the proposed road. When the support beam is required to bear a larger load, it can be achieved by increasing the beam height. The bottom elevation of the support beam must be higher than the top elevation of the proposed road construction limit. Further increasing the beam height upward is not limited by space, and only the rationality of the structural force and the economic efficiency of the section need to be considered.

[0032] According to an embodiment of the present invention, the structure of the upper half section of the dark excavation section of the single-arch single-span structure includes: providing support for the upper guide tunnel of the dark excavation section; providing a dark excavation section support beam 5-1 through the bottom surface of the upper guide tunnel of the dark excavation section in a direction perpendicular to the driving direction, wherein the distance between two adjacent dark excavation section support beams 5-1 is equal to the designed span of the single-arch single-span structure; providing support for the upper half section of the dark excavation section according to the structure of the upper guide tunnel of the dark excavation section; and providing the main structure of the upper half section of the dark excavation section.

[0033] According to an embodiment of the present invention, the main structure of the upper section of the dark excavation section includes: a secondary lining structure 4-1 of the upper section of the dark excavation section is constructed along the inner wall of the initial support 3-2 of the upper section of the dark excavation section, and together with the initial support 3-2 of the upper section of the dark excavation section, it forms a dark excavation section vault, and the lower end of the secondary lining structure 4-1 of the upper section of the dark excavation section is connected with the dark excavation section support beam 5-1, so that the cross-sections of multiple adjacent dark excavation section vaults present a continuous arch shape; the upper half part 6-1 of the dark excavation section end wall and the middle longitudinal beam 8-1 of the dark excavation section are constructed along the end face of the mountain side of the upper section of the dark excavation section, and the middle longitudinal beam 8-1 of the dark excavation section is located at the bottom of the upper half part 6-1 of the end wall and connected between two adjacent dark excavation section support beams 5-1.

[0034] In the construction method of the mountain shed tunnel in the embodiment of the present invention, the dark excavation section of each single-arch single-span structure is divided into the upper section of the dark excavation section (i.e., the construction working surface where the arch is located) and the lower section of the dark excavation section (which is connected for the passage of vehicles in the tunnel) according to the construction sequence and method. Accordingly, when the pilot tunnel excavation method commonly used in tunnel construction is applied, the upper pilot tunnel of the dark excavation section is excavated first before the excavation of the upper section of the dark excavation section. In the embodiment of the present invention, the purpose of excavating the upper pilot tunnel of the dark excavation section is to construct the dark excavation section support beam 5-1 shared by each two adjacent arches, and at the same time, a part of the upper section of the dark excavation section is excavated.

[0035] According to an embodiment of the present invention, the construction of a single-arch single-span open-type structure includes: determining a pile foundation or an expanded foundation as the foundation form of the open-type column 7-2 according to the terrain and geological conditions of the open-type section; when the pile foundation is selected, the open-type section column 7-2 is supported on the open-type section pile foundation 7-4 through the open-type section column bottom bearing platform 7-3; when the expanded foundation is selected, the open-type section column 7-2 is directly supported on the open-type section expanded foundation; according to the determined foundation form, on the air-facing side of the mountain slope 1 An exposed section column 7-2 is constructed, and a bottom longitudinal beam 8-3 between two adjacent exposed section column bases 7-3 or exposed section enlarged foundations is connected; an exposed section support beam 5-2 is constructed, which is connected with the dark excavation section support beam 5-1 to form a whole, and one end of the exposed section support beam 5-2 on the air side is supported on the exposed section column 7-2; an exposed section vault 4-2 is constructed above the exposed section support beam 5-2, which is connected with the secondary lining structure 4-1 of the upper half section of the dark excavation section to form an integral vault.

[0036] Different from the construction method of the open cut and backfill method in which the bearing structure is formed in one piece, and the semi-open and semi-dark method in which the single arch structure is formed by open cut and dark cut methods respectively on the cross section of the structure, the construction method of the embodiment of the present invention enables the arch of the open section and the arch of the dark cut section of the mountain-side shed tunnel to be formed in sections and finally connected to form a whole. Different foundation forms can be used for the columns of the open section according to the terrain and geological conditions. When the bedrock below the ground at the construction location of the tunnel is buried deep and the bearing capacity of the foundation is insufficient, the pile foundation form is applicable, and the bottom pedestal 7-3 of the open section column is arranged between the open section column 7-2 and the open section pile foundation 7-4; when the bedrock below the ground at the construction location of the tunnel is buried shallowly, the expanded foundation form is applicable, and the open section expanded foundation is directly connected to the open section column 7-2 above.

[0037] According to an embodiment of the present invention, the structure of the lower half section of the dark excavation section of the single-arch single-span structure includes: cleaning the mountain to align the excavation contour line of the lower guide tunnel of the dark excavation section with the excavation contour line of the upper guide tunnel of the dark excavation section; supporting the lower guide tunnel of the dark excavation section; casting the bottom longitudinal beam 8-2 of the dark excavation section connected to the two side walls of the lower guide tunnel of the dark excavation section at the bottom of the end face on the mountain side of the lower guide tunnel of the dark excavation section; casting the dark excavation section bottom longitudinal beam 8-2 at .... The bottom of the dark excavation section wall column 7-1 is vertically connected to the dark excavation section bottom longitudinal beam 8-2, and the top of the dark excavation section wall column 7-1 supports the dark excavation section support beam 5-1; the support of the lower guide tunnel of the dark excavation section is removed, and the lower half of the dark excavation section end wall 6-2 is constructed along the end face of the mountain side of the lower half section of the dark excavation section, and the lower half of the dark excavation section end wall 6-2 is connected to two adjacent dark excavation section wall columns 7-1.

[0038] Similar to the construction of the upper guide tunnel of the dark excavation section, the lower guide tunnel of the dark excavation section is excavated first before the lower half section of the dark excavation section is excavated. In the embodiment of the present invention, the purpose of excavating the lower guide tunnel of the dark excavation section is to construct the dark excavation section wall column 7-1 shared by every two adjacent arches (the wall column 7-1 and the dark excavation section support beam 5-1 supported above together constitute the dark excavation section structure in the form of a foundation shared by the arch feet of the adjacent single-arch single-span structure), and at the same time, excavate a part of the lower half section of the dark excavation section. Different from the construction of the upper half section, since the lower half section is ultimately used for the opening of the tunnel, after removing the support of the lower guide tunnel, it is only necessary to construct the lower half of the end wall 6-2 on the mountain side end face along the lower half section of the single-arch single-span structure dark excavation section.

[0039] According to an embodiment of the present invention, the support of the upper guide tunnel of the dark excavation section includes: constructing an advance support 2-1 of a large pipe shed for the upper guide tunnel of the dark excavation section outside the excavation contour line of the upper guide tunnel of the dark excavation section, and arranging it in a direction vertical to the driving direction; constructing an anchor rod 2-2 of the upper guide tunnel system of the dark excavation section as the paving surface of the upper guide tunnel of the dark excavation section advances, and the anchor rod 2-2 of the upper guide tunnel system of the dark excavation section is arranged around the upper guide tunnel of the dark excavation section; constructing an initial support 3-1 of the upper guide tunnel of the dark excavation section as the paving surface of the upper guide tunnel of the dark excavation section advances, and the initial support 3-1 is composed of a steel grating arch frame or a steel arch frame and a shotcrete support, and the steel grating arch frame or the steel arch frame is attached to the inner wall of the upper guide tunnel of the dark excavation section, and the shotcrete support covers the steel grating arch frame or the steel arch frame.

[0040] According to an embodiment of the present invention, according to the structure of the upper guide hole of the dark excavation section, the support of the upper half section of the dark excavation section includes: determining the remaining contour line of the upper half section of the dark excavation section according to the non-intersecting part of the excavation contour line of the upper half section of the dark excavation section and the excavation contour line of the upper guide hole of the dark excavation section; removing the structure of the large pipe shed advance support 2-1 of the upper guide hole of the dark excavation section and the anchor rod 2-2 of the upper guide hole system of the dark excavation section located inside the upper half section of the dark excavation section; constructing the large pipe shed advance support 2-3 of the upper half section of the dark excavation section outside the remaining contour line, and arranging the large pipe shed advance support 2-3 in the vertical direction of the driving direction. With the advancement of the mortar surface of the upper section of the dark excavation section, the system anchor rods 2-4 of the upper section of the dark excavation section are installed, and the system anchor rods 2-4 of the upper section of the dark excavation section are only arranged in the remaining contour line area around the hole of the upper section of the dark excavation section; with the advancement of the mortar surface of the upper section of the dark excavation section, the initial support 3-2 of the upper section of the dark excavation section is installed, which is composed of a steel grille arch frame or a steel arch frame and a shotcrete support. The steel grille arch frame or the steel arch frame is attached to the inner wall of the upper section of the dark excavation section, and the shotcrete support covers the steel grille arch frame or the steel arch frame.

[0041] According to an embodiment of the present invention, the support for the lower guide tunnel of the dark excavation section includes: constructing the lower guide tunnel system anchor rods 2-5 of the dark excavation section as the paving surface of the lower guide tunnel of the dark excavation section advances, and the lower guide tunnel system anchor rods 2-5 of the dark excavation section are arranged on the side walls of the lower guide tunnel of the dark excavation section; constructing the initial support 3-3 of the lower guide tunnel of the dark excavation section as the paving surface of the lower guide tunnel of the dark excavation section advances, which is composed of a steel grating arch frame or a steel arch frame and a shotcrete support, and the steel grating arch frame or the steel arch frame is attached to the inner wall of the lower guide tunnel of the dark excavation section, and the shotcrete support covers the steel grating arch frame or the steel arch frame.

[0042] For the construction of the dark excavation section of the mountainside tunnel, the corresponding support should be applied according to the mountain structure before and during the excavation. In the embodiment of the present invention, the initial support and protection shed tunnel structure composed of large pipe shed advance support, system anchor rods around the tunnel, and steel grid arch frame or steel arch frame and shotcrete support are respectively used. In the related art, affected by the complexity of the terrain of the proposed road and the horizontal and vertical linear design of the road, when the semi-bright and semi-dark method is used to construct the shed tunnel structure, the position of the original mountain natural slope surface in the cross section of the proposed road changes with the terrain trend. From the perspective of the excavation cross section, the boundary between the open part and the dark excavation part of the section changes with the "thickness" and "thinness" of the mountain to be excavated, fully exposing the characteristics and difficulty of the mountainside wiring. Due to the "thickness" and "thinness" changes of the mountain excavated by the dark excavation part in the cross section of the semi-bright and semi-dark method, it is more difficult to use large pipe sheds as advance support. At the same time, since the construction direction of the semi-bright and semi-dark method is longitudinally along the driving direction, excavating from both ends of the shed-tunnel entrance to the middle and finally penetrating, it is necessary that the construction direction of the large pipe shed and other advanced stratum reinforcement and advanced protection measures should also be longitudinally set along the proposed shed-tunnel. Limited by the construction technology, precision and effective action length of the large pipe shed, when the proposed shed-tunnel requires advanced protection throughout the entire length, there will be a situation where the tunnel section under some terrain conditions cannot be effectively protected. The construction direction of the mountain shed tunnel in the embodiment of the present invention is perpendicular to the driving direction, and the protection range of the advanced support only needs to cover the cross-sectional width of the proposed road. When the dark excavation section needs to be implemented with advanced support such as a large pipe shed, the effective protection length of the large pipe shed of 30m-40m in the prior art is sufficient to meet the actual needs of the project. At the same time, since the construction direction of the embodiment of the present invention is perpendicular to the driving direction, it is more conducive to excavating the hole perpendicular to the mountain contour line direction, and there are no problems such as uneven thickness and bias pressure caused by the half-bright and half-dark construction cross-section direction in the prior art.

[0043] According to an embodiment of the present invention, connecting the continuous arch structures to form a mountain-side shed tunnel includes: connecting multiple bottom longitudinal beams 8-2 of dark-cut sections along the driving direction; filling the roadbed backfill 9-2 below the road surface base of the proposed open-work section road, and when pile foundations are used, an open-work section pile retaining wall 9-1 for supporting the roadbed backfill 9-2 is arranged between two adjacent open-work section pile foundations 7-4; arranging an air-facing side retaining wall 9-3 above the open-work section arch 4-2 along the driving direction to support the mountain slope 1, the air-facing side retaining wall 9-3 and the arch backfill 11 between the arch enclosed area; constructing the internal roadbed and pavement, drainage pipe trench, curb collision prevention, maintenance walkway and other auxiliary structures 10 of the tunnel; when multiple sets of continuous arch structures are arranged continuously, a deformation joint is arranged between two adjacent sets of continuous arch structures.

[0044] In the related art, the construction of the shed tunnel structure generally does not distinguish between the upper and lower sections, and its construction working surface is the cross section of the entire shed tunnel structure or is divided into left and right parts according to the open section and the dark excavation section. Therefore, during the construction process, the bearing capacity of the shed tunnel structure is insufficient. In the embodiment of the present invention, the main structure of each single-arch single-span structure is first constructed, and then the lower half of the continuous arch structure that needs to be passed by vehicles is connected, which significantly improves the safety of the construction method of the mountainside shed tunnel. At the same time, in order to further enhance the force stability of the tunnel, a plurality of longitudinal beams are arranged in the tunnel. In addition, the area above the tunnel vault constructed by the open-cut method needs to be backfilled after the main structure is completed, and the area below the proposed roadbed needs to be filled with earth, stone or other backfill materials; further, the backfill below the roadbed needs to remain stable, otherwise it will lead to major safety problems such as roadbed collapse. Therefore, when a pile foundation is adopted, an open-section pile retaining wall 9-1 needs to be set between adjacent piles to bear the lateral pressure of the backfill 9-2 under the roadbed; backfill is also required above multiple tunnel vaults to restore the surface state and reduce the impact of falling rocks on the vault structure. Accordingly, an air-facing side retaining wall 9-3 needs to be set on the vault to support the vault backfill 11.

[0045] Figure 4-1 to Figure 4-9 Taking a mountain shed tunnel composed of a set of three-arch structures as an example, the specific construction process of each key step in the construction process of the embodiment of the present invention is specifically illustrated:

[0046] (1) According to the mountain slope 1, select a reasonable position to determine the boundary between the open section and the dark excavation section, clean the surface, and use manual excavation, mechanical excavation or drilling and blasting excavation according to geological conditions (the same for the following excavation methods). First, along the vertical direction of the proposed road, carry out the advance support of the large pipe shed on the upper guide hole of the dark excavation section 2-1; excavate the upper guide hole and carry out the initial support of the upper guide hole of the dark excavation section 3-1; install the upper guide hole system anchor rod 2-2 as the excavation is carried out, see Figure 4-1 .

[0047] (2) Cast-in-place reinforced concrete support beam 5-1 in the upper pilot tunnel, see Figure 4-2 .

[0048] (3) Carry out advance support 2-3 of large pipe shed for the arch of the dark excavation section; excavate the upper section of the shed tunnel structure and carry out initial support 3-2 of the arch of the dark excavation section along the hole of the upper section; carry out anchor rods 2-4 of the arch system of the dark excavation section as the excavation is carried out, see Figure 4-3 .

[0049] (4) Construct the secondary lining structure 4-1 of the arch top of the dark excavation section to form the group of continuous arch structures; construct the upper part 6-1 of the end wall of the dark excavation section and the middle longitudinal beam 8-1 of the dark excavation section. The middle longitudinal beam 8-1 of the dark excavation section can strengthen the integrity of the continuous arch structure and provide safety guarantee for the foundation stability when the lower half section of the dark excavation section shed tunnel structure is excavated. For details, see Figure 4-4 .

[0050] (5) According to the topographic and geological conditions of the exposed section, the column foundation form of the exposed section is reasonably selected, and the pile foundation or the expanded foundation can be used. Taking the pile foundation as an example, the exposed section pile foundation 7-4 is constructed, the exposed section column bottom pedestal 7-3 is constructed, the exposed section column 7-2 is constructed, the exposed section column bottom longitudinal beam 8-3 is constructed, the exposed section support beam 5-2 and the arch 4-2 are constructed, and the exposed section support beam 5-2 and the exposed section arch 4-2 are connected with the dark excavation section support beam 5-1 and the dark excavation section arch secondary lining structure 4-1 respectively to form a whole, see details Figure 4-5 .

[0051] (6) Excavate the lower section of the tunnel and implement the initial support 3-3 of the lower pilot tunnel of the dark excavation section; install the anchor rods 2-5 of the lower pilot tunnel system of the dark excavation section as the excavation progresses. For details, see Figure 4-6 .

[0052] (7) The lower half of the dark excavation section is excavated to the end of the dark excavation section on the side close to the mountain, and the dark excavation section wall columns 7-1 and the dark excavation section bottom longitudinal beams 8-2 are cast. Figure 4-7 .

[0053] (8) Remove the initial support 3-3 of the lower guide tunnel of the dark excavation section and the anchor rod 2-5 of the lower guide tunnel system of the dark excavation section; construct the lower half of the end wall 6-2 of the dark excavation section; connect the bottom longitudinal beam 8-2 of the dark excavation section to achieve the foundation bottoming of the tunnel shed structure close to the mountain side; construct the retaining wall between the piles of the exposed section 9-1; according to the condition that the bottom surface of the foundation is higher than the existing ground line, backfill the subgrade backfill 9-2 below the subgrade surface of the proposed road; see details Figure 4-8 .

[0054] (9) Construct the airside retaining wall 9-3 above the arch, backfill the arch backfill 11; construct the roadbed pavement, drainage pipe ditch, curb collision prevention, maintenance walkway and other auxiliary structures 10 inside the tunnel; the internal space of the tunnel meets the requirements of the proposed road construction limit 12 and the road traffic requirements; see Figure 4-9 .

[0055] The present invention has the following effects:

[0056] (1) The structural force transmission path is clear and the structural force is reasonable and controllable;

[0057] (2) The advanced stratum reinforcement and protection measures are reliable, the structural construction technology is mature, the construction work surface is large, and the construction efficiency is high;

[0058] (3) Avoid large-scale cutting of the mountain when building a tunnel along the mountain, maintain the stability of the mountain, and protect the natural environment and ecological landscape.

[0059] The above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications may be made based on the following description, and these various changes, modifications, substitutions and deformations derived from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A method for constructing a mountain shed tunnel, characterized in that: include: Concrete excavation sections and open excavation sections are constructed according to the mountain slope (1) to form a single-arch single-span structure with a span direction parallel to the preset driving direction; Constructing a plurality of the single-arch and single-span structures to form a continuous-arch structure; Connecting the continuous arch structures to form the mountainside shed tunnel; Wherein, constructing a concealed excavation section and an exposed section according to a mountain slope (1) to form a single-arch single-span structure whose span direction is parallel to a preset driving direction comprises: determining the boundary position of the concealed excavation section and the exposed section according to the mountain slope (1); constructing the structure of the upper half section of the concealed excavation section of the single-arch single-span structure; constructing the structure of the exposed section of the single-arch single-span structure; constructing the structure of the lower half section of the concealed excavation section of the single-arch single-span structure; The construction of the structure of the upper half section of the dark excavation section of the single-arch single-span structure comprises: constructing support for the upper guide hole of the dark excavation section; constructing a dark excavation section support beam (5-1) through the bottom surface of the upper guide hole of the dark excavation section in a direction perpendicular to the driving direction, wherein the distance between two adjacent dark excavation section support beams (5-1) is equal to the designed span of the single-arch single-span structure; constructing support for the upper half section of the dark excavation section according to the structure of the upper guide hole of the dark excavation section; and constructing the main structure of the upper half section of the dark excavation section; Wherein, constructing the exposed section structure of the single-arch single-span structure comprises: determining a pile foundation or an expanded foundation as the foundation form of the exposed section column (7-2) according to the topography and geological conditions of the exposed section; when the pile foundation is selected, the exposed section column (7-2) is supported on the exposed section pile foundation (7-4) through the exposed section column bottom bearing platform (7-3); when the expanded foundation is selected, the exposed section column (7-2) is directly supported on the exposed section expanded foundation; according to the determined foundation form, constructing the exposed section column on the air-facing side of the mountain slope (1) (7-2), a longitudinal beam (8-3) between two adjacent exposed section column bottom caps (7-3) or exposed section enlarged foundations is connected; an exposed section support beam (5-2) is constructed to be connected with the concealed section support beam (5-1) to form a whole, and one end of the exposed section support beam (5-2) facing the air side is supported on the exposed section column (7-2); an exposed section vault (4-2) is constructed above the exposed section support beam (5-2) to be connected with the secondary lining structure (4-1) of the upper half section of the concealed section to form a whole vault; The construction of the lower half section of the single-arch single-span structure comprises: cleaning the mountain to align the excavation contour line of the lower guide tunnel of the dark excavation section with the excavation contour line of the upper guide tunnel of the dark excavation section; supporting the lower guide tunnel of the dark excavation section; casting a dark excavation section bottom longitudinal beam (8-2) connected to two side walls of the lower guide tunnel of the dark excavation section at the bottom of the end face on the mountain side of the lower guide tunnel of the dark excavation section; casting a dark excavation section wall-attached column (7-1) at the end face on the mountain side of the lower guide tunnel of the dark excavation section. The bottom of the dark excavation section wall-attached column (7-1) is vertically connected to the dark excavation section bottom longitudinal beam (8-2), and the top of the dark excavation section wall-attached column (7-1) supports the dark excavation section support beam (5-1); the support of the lower guide tunnel of the dark excavation section is removed, and the lower half of the dark excavation section end wall (6-2) is constructed along the end face of the mountain side of the lower half section of the dark excavation section, and the lower half of the dark excavation section end wall (6-2) is connected to two adjacent dark excavation section wall-attached columns (7-1); Wherein, connecting the continuous arch structures to form the mountain-side shed tunnel comprises: connecting a plurality of the bottom longitudinal beams (8-2) of the dark-cut sections along the driving direction; filling the roadbed backfill (9-2) below the road surface base of the proposed open section road, and when a pile foundation is used, arranging an open section pile retaining wall (9-1) between two adjacent open section pile foundations (7-4) for supporting the roadbed backfill (9-2); arranging an air-facing side retaining wall (9-3) above the open section arch (4-2) along the driving direction, for supporting the mountain slope (1), the air-facing side retaining wall (9-3) and the arch backfill (11) between the arch enclosed area; constructing the tunnel's internal roadbed pavement, drainage pipe trench, curbstone anti-collision, maintenance walkway and other auxiliary structures (10); and arranging a deformation joint between two adjacent sets of the continuous arch structures when multiple sets of the continuous arch structures are arranged continuously.

2. The method according to claim 1, characterized in that The support of the pilot tunnel in the dark excavation section includes: A large pipe shed advance support (2-1) is provided outside the excavation contour line of the upper pilot tunnel of the dark excavation section, and is arranged in a direction perpendicular to the driving direction; As the upper pilot hole of the dark excavation section is advanced, anchor rods (2-2) of the upper pilot hole system of the dark excavation section are installed, and the anchor rods (2-2) of the upper pilot hole system of the dark excavation section are arranged around the upper pilot hole of the dark excavation section; As the paving surface of the upper guide tunnel of the dark excavation section is advanced, initial support (3-1) is implemented on the upper guide tunnel of the dark excavation section, which is composed of a steel grid arch frame or a steel arch frame and a shotcrete support. The steel grid arch frame or the steel arch frame is attached to the inner wall of the upper guide tunnel of the dark excavation section, and the shotcrete support covers the steel grid arch frame or the steel arch frame.

3. The method according to claim 2, characterized in that According to the structure of the guide tunnel on the dark excavation section, the support of the upper half section of the dark excavation section includes: Determine the remaining contour line of the upper half section of the dark excavation section according to the non-intersecting portion of the excavation contour line of the upper half section of the dark excavation section and the excavation contour line of the upper pilot tunnel of the dark excavation section; Dismantling the structure of the large pipe shed advance support (2-1) of the upper guide tunnel of the dark excavation section and the anchor rod (2-2) of the upper guide tunnel system of the dark excavation section located inside the upper half section of the dark excavation section; A large pipe shed advance support (2-3) is provided for the upper half section of the dark excavation section outside the remaining contour line and arranged in a direction perpendicular to the driving direction; As the upper half section of the dark excavation section is advanced, the upper half section system anchor rods (2-4) of the dark excavation section are installed, and the upper half section system anchor rods (2-4) of the dark excavation section are only arranged in the remaining contour line area around the upper half section of the dark excavation section; As the upper section of the dark excavation section is advanced, initial support (3-2) is implemented for the upper section of the dark excavation section, which consists of a steel grid arch frame or a steel arch frame and a shotcrete support. The steel grid arch frame or the steel arch frame is attached to the inner wall of the upper section of the dark excavation section, and the shotcrete support covers the steel grid arch frame or the steel arch frame.

4. The method according to claim 3, characterized in that The main structure of the upper half section of the dark excavation section includes: A secondary lining structure (4-1) of the upper section of the dark excavation section is constructed along the inner wall of the initial support (3-2) of the upper section of the dark excavation section, and together with the initial support (3-2) of the upper section of the dark excavation section, forms a dark excavation section vault, and the lower end of the secondary lining structure (4-1) of the upper section of the dark excavation section is connected to the dark excavation section support beam (5-1), so that the cross-sections of a plurality of adjacent dark excavation section vaults present a continuous arch shape; An upper half portion (6-1) of the dark excavation section end wall and a middle longitudinal beam (8-1) of the dark excavation section are constructed along the end face of the mountain side of the upper half section of the dark excavation section. The middle longitudinal beam (8-1) of the dark excavation section is located at the bottom of the upper half portion (6-1) of the end wall and is connected between two adjacent support beams (5-1) of the dark excavation section.

5. The method according to claim 1, characterized in that The support of the lower guide tunnel of the dark excavation section includes: As the subgrade surface of the guide tunnel under the dark excavation section is advanced, anchor rods (2-5) of the guide tunnel system under the dark excavation section are installed, and the anchor rods (2-5) of the guide tunnel system under the dark excavation section are arranged on the side wall of the guide tunnel under the dark excavation section; As the subgrade surface of the lower guide tunnel of the dark excavation section is advanced, initial support (3-3) is implemented for the lower guide tunnel of the dark excavation section, which is composed of a steel grid arch frame or a steel arch frame and a shotcrete support. The steel grid arch frame or the steel arch frame is attached to the inner wall of the lower guide tunnel of the dark excavation section, and the shotcrete support covers the steel grid arch frame or the steel arch frame.

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