CN114856616A - Tunnel construction method and reinforced protection structure - Google Patents

Abstract

The embodiment of the application provides a tunnel reinforcing protective structure and a construction method applying the protective structure, the tunnel reinforcing protective structure comprises a protective structure and a reinforcing structure, the protective structure comprises an isolation protective pile, a horizontal isolation pipe shed and a tunnel top-inserted large pipe shed, and the isolation protective pile and the horizontal isolation pipe shed are used for blocking horizontal and vertical deformation of a passing road caused by tunnel construction. The tunnel top is inserted big pipe shed and is used for guaranteeing the safety of the existing railway facilities of tunnel top, prevents to collapse, and the reinforcing structure includes supporting pile and the just roof beam of D type for treat the existing railway facilities of excavation tunnel top in the work progress and support the reinforcement. By verification, the reinforced protection structure and the construction method can ensure the stability of the soil body above the tunnel and can meet the operation safety of the existing municipal roads and railways.

Description

Tunnel construction method and reinforced protection structure

Technical Field

The application relates to the technical field of road and bridge construction, in particular to a tunnel construction method and a reinforced protection structure.

Background

With the rapid development of modern economy, almost all large cities have traffic jam and fall-behind facilities such as city matching pipelines, municipal works, highway engineering, matching pipelines and the like cannot meet the increasing requirements of local traffic and matching facilities, and the newly-increased construction requirements of public traffic facilities such as subways, light rails, municipal roads and the like are urgent.

In urban areas, a large number of existing railway facilities such as urban railway lines, railway related buildings and the like exist, it is often inevitable to newly add municipal railways, highway engineering, pipelines and the like to run the existing railway facilities downwards, usually, the running position should be selected at a position with small interference to the operation of the existing railway facilities, and in order to ensure the operation safety of the existing railways and the municipal roads in the tunnel excavation construction process, reliable measures must be taken to enable deformation indexes caused by construction to meet the requirements of specifications and design. When the underground tunnel penetrates through the existing railway facilities, when the buried depth is deep, reinforcing measures such as grouting and the like can be adopted in the tunnel hole to be combined with reinforcing measures of a ground surface longitudinal beam and a 3-5-3 buckling rail (the heavy steel rail and steel fastener and bolt connection are used for forming the longitudinal beam and the transverse beam), so that the deformation requirement of the existing railway facilities can be met.

However, the construction of underground tunnels is sometimes limited by road and pipeline planning, terrain, etc., and it is also inevitable to cross over from a location where existing railway facilities are busy, for example, a level crossing of an existing railway. The position of the level crossing is generally of an integral reinforced concrete slab structure, and because the tunnel is covered with shallow soil, an arch effect cannot be formed, and the deformation indexes of the existing railway and municipal roads cannot meet the operation safety requirements. The existing strengthening measures such as grouting and the like adopted in the tunnel hole are combined with ground surface longitudinal and transverse beams and 3-5-3 track buckling strengthening measures, so that the stability of the soil body above the tunnel cannot be ensured, and the operation safety of the existing municipal roads and railways cannot be met.

Disclosure of Invention

In order to solve one of the technical defects, the embodiment of the application provides a reinforcing and protecting structure of a tunnel and a construction method applying the structure.

According to a first aspect of the embodiment of the application, a reinforced protection structure of a tunnel is provided, which comprises a protection structure and a reinforced structure, wherein the protection structure comprises isolation protection piles, a horizontal isolation pipe shed and a tunnel top-inserted large pipe shed, the isolation protection piles are arranged on one side or two sides of the tunnel to be excavated, the horizontal isolation pipe shed is arranged on the outer side of the isolation protection piles, and the tunnel top-inserted large pipe shed is arranged at the top of the tunnel to be excavated; the reinforcing structure comprises support piles and temporary beams, the temporary beams comprise longitudinal beams and transverse beams, the temporary beams are erected on the support piles, and the temporary beams are arranged under existing railway facilities above the tunnel to be excavated. According to a second aspect of the embodiments of the present application, there is provided a method for constructing a tunnel, the method for constructing a reinforced protection structure of a tunnel as described above, the method comprising the following specific steps:

setting a construction vertical shaft, setting the construction vertical shaft at the designed starting point of the tunnel, and performing vertical shaft high-pressure jet grouting pile and ring beam construction;

the construction of a protective structure, wherein the construction of the reinforced protective structure comprises the steps of carrying out the horizontal isolation pipe shed construction, the tunnel top-inserted large pipe shed construction and the isolation protective pile construction according to the erection position of claim 1, and carrying out the support pile construction in the reinforced structure below the position where the existing railway facility needs to be erected;

constructing a reinforced structure, namely erecting a D-shaped temporary beam on the supporting pile to support and reinforce the existing railway facilities;

and (3) tunnel subsurface excavation construction, wherein the tunnel is excavated after the step of reinforcing structure construction is executed, the tunnel subsurface excavation construction adopts a sectional excavation mode, firstly excavation construction is carried out on one side of the existing railway facility, and then excavation construction is carried out on the other side of the existing railway facility above the tunnel to be excavated.

By adopting the reinforcing and protecting structure of the tunnel and the construction method applying the structure, provided by the embodiment of the application, temporary guide and modification and amplitude-division passing are carried out on the existing municipal road, so that the operation of the existing railway facilities is ensured; in the construction process, measures of isolating protective piles and horizontal isolating pipe sheds are adopted beside the tunnel to block horizontal and vertical deformation of a soil body caused by tunnel construction, so that the stability and safety of existing railway facilities are guaranteed; the safety of the existing railway facilities at the top of the tunnel is ensured by taking measures of inserting a large pipe shed at the top of the tunnel, and collapse is prevented; in addition, a method for reinforcing the beam frame space of the existing railway facilities is adopted to meet the requirements of deformation and stress of the existing railway facilities. By verification, the reinforced protection structure and the construction method can ensure the stability of the soil body above the tunnel and can meet the operation safety of the existing municipal roads and railways.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 is a schematic plan structure view of a reinforced protection structure of a tunnel according to an embodiment of the present application;

fig. 2 is a schematic elevation structure view of a reinforced protection structure of a tunnel according to an embodiment of the present application;

fig. 3 is a schematic flow chart of a tunnel construction method according to an embodiment of the present application;

fig. 4 is a schematic flow chart illustrating a construction process of a reinforcing structure of a tunnel according to an embodiment of the present application;

fig. 5 is a schematic flow chart illustrating tunnel excavation construction steps of a tunnel according to an embodiment of the present application;

fig. 6 is a schematic flowchart of a tunnel cleaning and acceptance step provided in the embodiment of the present application.

Reference numerals:

1, constructing a vertical shaft; 2-a tunnel to be excavated; 3-isolating the fender pile; 4-horizontal isolation pipe shed; 5-D type temporary beam; 6-supporting the pile; 7-temporary buttress; 8-crossing plate; 9-large pipe shed.

Detailed Description

In order to make the technical solutions and advantages of the embodiments of the present application more apparent, the following further detailed description of the exemplary embodiments of the present application with reference to the accompanying drawings makes it clear that the described embodiments are only a part of the embodiments of the present application, and are not exhaustive of all embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

In the process of implementing the application, the inventor finds that shallow-buried underground excavation tunnel construction is carried out at a position where the tunnel soil covering is shallow, because the soil covering is shallow, an arch effect cannot be formed, the deformation index of the existing railway and the municipal road cannot meet the operation safety requirement, and the existing reinforcing measures such as grouting and the like adopted in the tunnel hole are combined with ground surface longitudinal and transverse beams and 3-5-3 track buckling reinforcing measures, so that the stability of the soil body above the tunnel cannot be ensured, and the operation safety of the existing municipal road and the railway cannot be met.

In order to solve the above problems, the embodiment of the application provides a tunnel reinforcing protection structure and a tunnel construction method using the protection structure, so that when tunnel construction is performed at a position where tunnel soil covering is shallow, stability of soil above the tunnel can be guaranteed, and existing municipal road and railway operation safety can be met.

In order to clearly and clearly explain the technical scheme of the application, the embodiment of the application adopts a specific application scenario that the shallow-buried underground tunnel passes through the existing railway level crossing, but it is noted that the technical scheme of the application is not only applied to the application scenario, but also can be applied to all construction scenarios of shallow-buried underground tunnels with shallow covered soil.

Fig. 1 is a schematic plan structure view of a reinforced protection structure of a tunnel according to an embodiment of the present application; fig. 2 is a schematic elevation structure diagram of a reinforced protection structure of a tunnel provided in an embodiment of the present application, and as shown in fig. 1 and fig. 2, the reinforced protection structure of the tunnel according to the embodiment of the present application includes a protection structure and a reinforcing structure, where the protection structure is erected before tunnel construction, the protection structure includes an isolation fender pile 3, a horizontal isolation pipe shed 4, and a tunnel top-inserted large pipe shed 9, the isolation fender pile 3 is disposed on one side or both sides of the tunnel 2 to be excavated, the horizontal isolation pipe shed 4 is disposed on the outer side of the isolation fender pile 3 (the side of the isolation fender pile 3 close to the tunnel 2 to be excavated is an inner side), the tunnel top-inserted large pipe shed 9 is disposed on the top of the tunnel 2 to be excavated, and the cross-sectional shape thereof is determined according to the needs of a geological structure and is generally an arc shape concentric with the vault of the tunnel; the reinforced structure is erected before and during construction, existing railway facilities above a tunnel to be excavated can be supported and reinforced, the reinforced structure comprises support piles 6 and temporary beams 5, the temporary beams comprise longitudinal beams and transverse beams, the longitudinal beams are erected on the support piles 6 and/or temporary buttresses 7, and the existing railway facilities above the tunnel to be excavated are erected on a framework formed by the longitudinal beams and the transverse beams.

The stress state of the surrounding rock is changed again after the tunnel is excavated and unloaded, and the pressure at the bottom of the tunnel is reduced to cause the bottom to deform and swell: meanwhile, the tunnel supporting structure deforms to cause the tunnel surrounding rock to slide into the tunnel, an isolation protection pile is arranged between the tunnel supporting structure and a protected building, the pile body is inserted into a stable soil layer at the lower part of the sliding surface, and the thrust of the sliding body is balanced through the resistance to the pile, so that balance and stability are achieved. When the tunnel surrounding rock slides into the tunnel, the tunnel surrounding rock is subjected to the impedance of the pile body, so that the sliding body in front of the pile reaches a stable state, and the displacement deformation of the soil body behind the pile is controlled, thereby reducing the deformation of facilities or buildings around the tunnel and playing a role in protecting the existing railway facilities and/or buildings.

The pipe shed structure is an advance support structure, and the horizontal isolation pipe shed is in the outside of keeping apart the fender pile (keep apart the fender pile and be inboard near the one side of tunnel main part), is on a parallel with the thick wall steel pipe that lies in of keeping apart the fender pile and drills in advance and install moment of inertia great, further plays advance support's effect. On the one hand, the horizontal isolation pipe shed further improves the soil body rigidity on the whole on the basis of isolating the protection piles, and can prevent the soil body from horizontally deforming. On the other hand, when the soil body is disturbed by tunnel construction, the soil bodies around the protective isolation piles and the horizontal isolation pipe sheds are unevenly deformed, so that soil particles are mutually wedged, a soil arch effect occurs in a soil layer in a certain area, the horizontal deformation of the soil body behind the piles is effectively prevented, the horizontal isolation pipe sheds are densely arranged, the soil arch effect is obvious, and the horizontal displacement of the soil body around the tunnel in the construction process can be effectively isolated by matching the protective isolation piles.

The tunnel top inserted large pipe shed 9 is characterized in that holes are pre-drilled and thick-wall steel pipes with large inertia moment are installed on a lining arch ring hidden submerged arc line of an excavated underground tunnel or structural engineering to play a role of temporary advanced support, so that soil layer collapse and ground surface subsidence are prevented, and safe operation of tunneling and subsequent support processes is ensured.

The D-shaped temporary beam is suitable for bridge and tunnel construction of existing lines or stations, and has the greatest advantage that the operation of existing railway facilities can be guaranteed in the construction process, for example, the D-shaped temporary beam is used for supporting existing railways or municipal roads, and the D-shaped temporary beam can be used for excavating and constructing tunnels under the condition of not interrupting driving. Because of these characteristics, the D-shaped beam has been widely used, and in order to save design and production costs, the D-shaped beam is preferred in the embodiment of the present application.

By adopting the structure, when the shallow-buried and underground-excavated tunnel construction is carried out at the shallow position of the tunnel earthing, the stability of the soil body above the tunnel can be ensured, and the safety of the operation of the existing municipal road and railway can be met.

The embodiment of the present application further provides a tunnel construction method using the reinforced protection structure, fig. 3 is a schematic flow chart of the tunnel construction method provided in the embodiment of the present application, and as shown in fig. 3, the specific construction steps include:

step 200: setting a construction vertical shaft 1, setting the construction vertical shaft at the design starting point of the tunnel, and performing vertical shaft high-pressure jet grouting pile and ring beam construction;

step 300: the construction of a protective structure, wherein the construction of the reinforced protective structure comprises the steps of carrying out horizontal isolation pipe shed construction, tunnel top-inserted large pipe shed construction and isolation protective pile construction according to the erection position of the reinforced supporting structure of the tunnel, and carrying out support pile construction in the reinforced structure below the position where the existing railway facility (such as the existing railway) needs to be erected;

step 400: constructing a reinforced structure, namely erecting a D-shaped temporary beam on a support pile to support and reinforce the existing railway facilities (such as the existing railway);

step 500: and after the step of reinforcing structure construction is carried out, tunnel underground excavation construction is carried out, the tunnel construction adopts a sectional excavation mode, excavation construction is carried out on one side of the existing railway facility (such as the existing railway) firstly, and then excavation construction is carried out on the other side of the existing railway facility above the tunnel to be excavated.

Wherein, before performing step 200, step 100 may be performed: preparing before construction, wherein the step of preparing before construction comprises temporary traffic diversion and frame passing; taking the case of passing a subsurface tunnel under the existing railway level crossing as an example, temporary diversion is carried out according to a plan before construction, and if necessary, the way is changed, so as to guide trains to pass at different times;

after step 500, step 600 may be performed: and (4) cleaning and acceptance inspection, namely cleaning, recovering and acceptance inspection of the construction site after the construction is finished.

If the construction scene is that the tunnel is penetrated under the existing railway level crossing, the crossing plate 8 needs to be dismantled before the tunnel is excavated and the D-shaped temporary beam is erected, and railway ballast, sleepers, steel rails and the like are laid, and in order to ensure traffic, the removal of the crossing plate 8 needs to be carried out in a skylight point.

Fig. 4 is a schematic flowchart of a construction step of a reinforced structure of a tunnel according to an embodiment of the present application, and as shown in fig. 4, the construction step of the reinforced structure further includes:

step 401: assembling the temporary beam, namely, after the longitudinal beam is hoisted in place by adopting a crane, connecting the temporary beam with the cross beam, and assembling the D-shaped temporary beam 5;

step 402: erecting a temporary beam, and gradually raising the longitudinal beam after the D-shaped temporary beam 5 is assembled to enable the D-shaped temporary beam 5 and the support pile to bear the weight;

step 403: and inspecting and maintaining the D-shaped temporary beam in the tunnel construction process.

Taking the existing railway level crossing junction to penetrate the shallow buried underground tunnel as an example, the concrete mode of assembling the temporary beam is as follows:

1) and hoisting and conveying the steel sleepers to two sides of the line by using a crane. The positions of the steel sleepers marked on the line (marked on the rail waist) are marked according to the distance between the steel sleepers. And (3) adjusting the distance between the sleepers by utilizing the slow movement interval of the train before a locking point, adjusting the distance between the sleepers, extracting redundant sleepers, and inserting the D-shaped temporary beam steel sleepers into the gaps. The penetration of the steel sleeper is perpendicular to the line, namely the middle part is arranged at the first and the two sides are arranged at the second.

2) Hoisting the longitudinal beam, parking a large-tonnage crane on one side of the circuit, hoisting the longitudinal beam on one side, hoisting the longitudinal beam on the other side, hoisting the longitudinal beam in place, connecting the steel sleepers at two ends of each hole girder with the longitudinal beam, and then connecting and assembling other steel sleepers.

3) After the steel sleeper and the longitudinal beam of the D-shaped temporary beam are connected into a whole and erected, the longitudinal beam is gradually lifted, and the longitudinal beam is slowly stressed, so that a railway line bears weight on the longitudinal beam. When the longitudinal beam is lifted, a field technician performs leveling control to control the elevation consistency of four corners of the longitudinal beam and the smoothness of a track line of a construction section.

The embodiment of the application provides specific operation steps for tunnel underground excavation construction, and fig. 5 is a schematic flow chart of tunnel underground excavation construction steps of a tunnel provided by the embodiment of the application. As shown in fig. 5, the tunnel excavation construction provided by the embodiment of the present application includes:

step 501: and (5) excavating preparation, namely determining a tunnel excavating mode by combining site geological factors.

Adopting one or a combination of a full section method, a step method, a middle partition wall method and a double side wall pit guiding method;

step 502: grouting the roadbed and the foundation, and reserving a small roadbed grouting conduit after grouting of the roadbed and the foundation is solidified;

step 503: and (5) excavating the tunnel, namely excavating the tunnel from the construction vertical shaft until the design mileage is reached.

The tunnel excavation step comprises tunnel longitudinal construction and tunnel transverse construction, and if the step method construction is adopted, the tunnel faces of the tunnel longitudinal construction need to be staggered by a distance not less than 3 m. And the tunnel transverse construction step comprises:

step 504: performing primary support construction, namely constructing and erecting a primary support protection structure after soil excavation is finished;

step 505: and (4) waterproof layer construction, namely laying a waterproof layer after primary support construction is finished.

The waterproof layer construction adopts geotextile as a buffer layer, the waterproof coiled material as a waterproof board, and the double-welding-seam laying mode is adopted for laying;

step 506: and (4) secondary lining construction, wherein the secondary lining construction is carried out after the waterproof layer construction is finished.

If the step method construction is adopted, the upper step part and the lower step part need to be excavated in sequence, the primary support construction of the part is carried out after the excavation of each part is finished, and the waterproof layer construction needs to be from bottom to top.

Further, the primary support construction method comprises the following steps:

primarily spraying concrete, and primarily spraying concrete after the tunnel excavation is finished; the initial concrete spraying needs to be carried out immediately after the excavation is finished, and the excavation surface is closed and leveled in time to prevent the surface of the surrounding rock from weathering and stripping off.

Erecting a grid steel frame, and erecting the grid steel frame close to the surface of the primary sprayed concrete after the primary sprayed concrete is finished;

and (5) re-spraying concrete, and re-spraying concrete after the grid steel frame is erected. And (3) spraying the concrete again to the designed thickness in 3 times after the section steel frame construction is finished and the concrete is qualified after inspection.

Furthermore, the grid steel frame is erected in a mode of assembling standard finished product units on site, all finished product units are welded together by adopting connecting ribs, the grid steel frame is positioned by adopting a foot locking anchor pipe and is anchored, and a gap between the grid steel frame and a concrete surface formed after concrete is primarily sprayed is filled with concrete blocks.

Further, the secondary lining construction comprises the following steps: binding bottom plate reinforcing steel bars, supporting a bottom template, pouring bottom plate concrete, binding side walls and vault reinforcing steel bars, supporting side walls and vault templates, pouring side walls and vault concrete, backfilling and grouting after two backings. The substeps belong to the existing mature technology and are not described in detail.

The bottom formwork, the side wall and the vault formwork adopt combined formworks, the step of back-filling and grouting after two backings is carried out after the bottom concrete, the side wall and the vault concrete reach the design strength, and the step of back-filling and grouting after two backings is carried out by adopting cement paste for grouting.

Fig. 6 is a schematic flow chart of the tunnel cleaning and acceptance step provided in the embodiment of the present application, and as shown in fig. 6, the tunnel cleaning and acceptance step includes an existing railway facility recovery step, and the existing railway facility recovery step includes:

step 601: treating the foundation of the bottom of the existing railway facility;

step 602: d-shaped temporary beams are dismantled;

step 603: restoring existing railway facilities;

step 604: cleaning the site and checking and accepting the project.

Further, the treatment of the foundation at the bottom of the existing railway facility comprises hollowing the lower part of the existing railway facility according to the designed elevation; concrete is poured below the existing railway facility, elevation leveling is carried out on the concrete by cement mortar, or/and a concrete cushion is poured below the existing railway facility, a reinforced concrete base layer is poured above the concrete cushion, and the widths of the concrete cushion and the concrete base layer are larger than the width of the existing railway facility.

Take existing railway level crossing department to wear shallow buried undercut tunnel down as an example, need reinstallate crossing board and crossing board platform in clearance and acceptance step, concrete operation flow is: foundation treatment of the crossing plate and the crossing platform bottom → dismantling of the line under the D-shaped temporary beam 5 → dismantling of the D-shaped temporary beam 5 → installation of the crossing plate → railway track laying and restoration → pavement of the crossing platform.

When the foundation treatment of the crossing plate and the crossing platform bottom is carried out, the crossing plate and the lower part of the crossing platform are hollowed according to the designed elevation, the ground railway line (namely the existing railway facility) is completely supported by the D-shaped temporary beam 5 in the process, C15 concrete is poured after the lower part of the installed crossing plate is hollowed, and the elevation leveling is carried out on the upper part by cement mortar; and C15 cushion layers are poured below the crossing platform, C35 reinforced concrete base layers are poured above the cushion layers, and the cushion layers and the base layers are 10cm wider than the crossing platform.

And (4) finishing the treatment of the crossing plate and the foundation of the crossing platform bottom, and dismantling the ground railway line after the concrete reaches certain strength. The original rail is sawn off and lifted out, and then the sleeper is lifted out.

D-shaped temporary beams are further dismantled after the original steel rails are dismantled, and the D-shaped temporary beams are dismantled according to the reverse order of the installation of the steel temporary beams.

The crossing plate to be installed is transported to the site by the prefabricating field 1 day in advance, the crossing plate is installed on a cement mortar cushion layer according to the designed position and the elevation by matching with a crane, the smoothness of the crossing plate is ensured during installation, and the phenomena of corner warping and suspension are avoided.

After the crossing plate is installed, the railway track is laid and restored, and 50 steel rails of 25 m/root are installed in the groove of the crossing plate and fixed.

After the railway track is paved and restored, the crossing platform is paved on a concrete base layer, and a gap of 3cm is reserved between the crossing platform and the crossing plate. During installation, the elevation control is noticed, and vehicles at the joint of the crossing plate, the crossing platform and the luggage road can stably pass through.

And finally checking and accepting after all the materials are recovered to the original state.

In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be considered as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically connected, electrically connected or can communicate with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (14)

1. The utility model provides a protective structure is consolidated to tunnel which characterized in that: the reinforced protective structure comprises:

the protective structure comprises isolation protective piles, a horizontal isolation pipe shed and a tunnel top-inserting large pipe shed, wherein the isolation protective piles are arranged on one side or two sides of the tunnel to be excavated, the horizontal isolation pipe shed is arranged on the outer side of the isolation protective piles, and the tunnel top-inserting large pipe shed is arranged at the top of the tunnel to be excavated;

the reinforced structure comprises support piles and temporary beams, the temporary beams comprise longitudinal beams and transverse beams, the temporary beams are erected on the support piles, and the temporary beams are arranged under existing railway facilities above the tunnel to be excavated.

2. A construction method of a tunnel is characterized in that the construction method of the tunnel adopts the tunnel reinforcing and protecting structure as claimed in claim 1, and the concrete construction steps comprise:

setting a construction vertical shaft, setting the construction vertical shaft at the designed starting point of the tunnel, and performing vertical shaft high-pressure jet grouting pile and ring beam construction;

the construction of a protective structure, wherein the construction of the reinforced protective structure comprises the steps of carrying out the horizontal isolation pipe shed construction, the tunnel top-inserted large pipe shed construction and the isolation protective pile construction according to the erection position of claim 1, and carrying out the support pile construction in the reinforced structure below the position where the existing railway facility needs to be erected;

constructing a reinforced structure, namely erecting an auxiliary beam on the supporting pile, and supporting and reinforcing the existing railway facilities;

and (3) carrying out tunnel subsurface excavation construction, excavating the tunnel after the step of reinforcing structure construction is carried out, wherein the tunnel construction adopts a sectional excavation mode, firstly carrying out excavation construction on one side of the existing railway facility, and carrying out excavation construction on the other side of the existing railway facility above the tunnel to be excavated.

3. The construction method of a tunnel according to claim 2, wherein the reinforcing structure construction step includes:

assembling the temporary beam, namely, after the longitudinal beam is hoisted in place by adopting a crane, connecting the temporary beam with the cross beam and assembling the temporary beam;

erecting a temporary beam, and gradually raising the longitudinal beam after the temporary beam is assembled so as to bear the load of the temporary beam and the support pile;

and inspecting and maintaining the temporary beam in the tunnel construction process.

4. The method of constructing a tunnel according to claim 3, wherein a field technician performs leveling control when raising the longitudinal beams in the step of erecting the temporary beams.

5. The tunnel construction method according to claim 2, wherein the tunnel excavation construction step includes:

preparing excavation, namely determining a tunnel excavation mode by combining site geological factors, and adopting one or a combination of a full section method, a step method, a middle partition wall method and a double-side wall pit guiding method;

grouting the roadbed and the foundation, and reserving a small roadbed grouting conduit after grouting of the roadbed and the foundation is solidified;

the tunnel excavation, by construction shaft department excavation tunnel, until the design mileage, the tunnel excavation step includes the vertical construction of tunnel and the horizontal construction of tunnel, and wherein the horizontal construction of tunnel includes:

performing primary support construction, namely constructing and erecting a primary support protection structure after soil excavation is finished;

constructing a waterproof layer, namely laying the waterproof layer after the primary support construction is finished;

and (4) secondary lining construction, wherein the secondary lining construction is carried out after the waterproof layer construction is finished.

6. The method of constructing a tunnel according to claim 5, wherein the preliminary bracing construction includes:

primarily spraying concrete, and primarily spraying concrete after the tunnel excavation is finished;

erecting a grid steel frame, and erecting the grid steel frame close to the surface of the primary sprayed concrete after the primary sprayed concrete is finished;

and (5) re-spraying concrete, and re-spraying concrete after the grid steel frame is erected.

7. The tunnel construction method according to claim 6, wherein: the grid steel frame is erected in a standard finished product unit field assembly mode, all finished product units are welded together through connecting ribs, the grid steel frame is positioned and anchored through foot locking anchor pipes, and gaps between the grid steel frame and a concrete surface formed after concrete is initially sprayed are filled with concrete blocks.

8. The tunnel construction method according to claim 6, wherein: in the concrete re-spraying step, a multi-time re-spraying mode is adopted until the designed thickness is reached.

9. The tunnel construction method according to claim 6, wherein: the waterproof layer construction adopts geotechnical cloth as the buffer layer, and waterproofing membrane is as the waterproof board, uses the mode of two welding seams to lay.

10. The method of constructing a tunnel according to claim 6, wherein the step of secondary lining construction includes: binding bottom plate reinforcing steel bars, supporting a bottom template, pouring bottom plate concrete, binding side walls and vault reinforcing steel bars, supporting side walls and vault templates, pouring side walls and vault concrete, backfilling and grouting after two backings.

11. The method of claim 10, wherein the bottom form, the side walls and the arch form are combined forms, the step of two-backing post-backfill grouting is performed after the bottom concrete, the side walls and the arch concrete reach the designed strength, and the step of two-backing post-backfill grouting is performed by using cement slurry for grouting.

12. The construction method of a tunnel according to claim 2, further comprising the steps of:

preparing before construction, wherein the step of preparing before construction comprises temporary traffic diversion and frame passing;

and (4) cleaning and acceptance inspection, namely cleaning, recovering and acceptance inspection of the construction site after the construction is finished.

13. The tunnel construction method according to claim 12, wherein: the cleaning and acceptance steps comprise an existing railway facility recovery step, and the existing railway facility recovery step comprises: the method comprises the steps of treating the foundation at the bottom of the existing railway facility, dismantling the temporary beam, recovering the existing railway facility, cleaning the site and checking and accepting the project.

14. The tunnel construction method according to claim 13, wherein: the existing railway facility bottom foundation treatment comprises the following steps of hollowing the lower part of the existing railway facility according to the designed elevation; concrete is poured below the existing railway facility, elevation leveling is carried out on the concrete by cement mortar, or/and a concrete cushion is poured below the existing railway facility, and a reinforced concrete base layer is poured above the concrete cushion, wherein the widths of the concrete cushion and the concrete base layer are both larger than the width of the existing railway facility.

Images