A tunnel construction method and reinforced protective structure

Abstract

The embodiment of the present application provides a tunnel reinforcement protection structure and a construction method using such a protection structure. The reinforcement protection structure of such a tunnel includes a protection structure and a reinforcement structure. The protection structure includes isolation protection piles, a horizontal isolation pipe shed, and a large pipe shed inserted on the top of the tunnel. The isolation protection piles and the horizontal isolation pipe shed are used to block the horizontal and vertical deformation of the passage caused by tunnel construction. The large pipe shed inserted on the top of the tunnel is used to ensure the safety of the existing railway facilities on the top of the tunnel and prevent collapse. The reinforcement structure includes support piles and D-shaped temporary beams, which are used to support and reinforce the existing railway facilities above the tunnel to be excavated during the construction process. It has been verified that the use of the above-mentioned reinforcement protection structure and construction method can ensure the stability of the soil above the tunnel and meet the safety of existing municipal roads and railway operations.

Description

Technical Field

[0001] The present application relates to the technical field of road and bridge construction, and more specifically, to a tunnel construction method and a reinforced protective structure. Background Art

[0002] With the rapid development of the modern economy, almost all large cities have traffic congestion and backward urban supporting pipelines and other facilities. Their municipal and highway projects and supporting pipelines can no longer meet the growing requirements of local transportation and supporting facilities. The need for new construction of public transportation facilities such as subways, light rails, and municipal roads is very urgent.

[0003] However, there are already a large number of existing railway facilities in urban areas, such as urban railway lines and railway-related buildings, etc. It is often inevitable to add new municipal railways or highway projects and pipelines under existing railway facilities. Usually, the underpass location should be selected at a location that has less interference with the operation of existing railway facilities. In addition, in order to ensure the safety of existing railways and municipal roads during the tunnel excavation construction, reliable measures must be taken to ensure that the deformation indicators caused by construction meet the specifications and design requirements. When an underground tunnel passes under existing railway facilities, when the burial depth is deep, reinforcement measures such as grouting can be taken in the tunnel hole in combination with surface longitudinal and transverse beams and 3-5-3 rail buckle reinforcement measures (heavy rails plus steel fasteners, bolted to form longitudinal and transverse beams.) The deformation requirements of existing railway facilities can be guaranteed.

[0004] However, the construction of underground tunnels is sometimes restricted by road and pipeline planning and terrain, and it is inevitable to pass through locations where existing railway facilities are busy, such as existing railway level crossings. At such level crossings, an integral reinforced concrete slab structure is usually used. Since the tunnel cover is very shallow, an arch effect cannot be formed, and the deformation indicators of existing railways and municipal roads cannot meet the operational safety requirements. The existing reinforcement measures such as grouting in the tunnel combined with the surface longitudinal and transverse beams and 3-5-3 rail buckle reinforcement measures cannot guarantee the stability of the soil above the tunnel, and cannot meet the operational safety requirements of existing municipal roads and railways. Summary of the invention

[0005] In order to solve one of the above-mentioned technical defects, an embodiment of the present application provides a tunnel reinforcement protection structure and a construction method using such a structure.

[0006] According to the first aspect of the embodiment of the present application, a reinforcement and protection structure of a tunnel is provided, which includes a protection structure and a reinforcement structure. The protection structure includes isolation and protection piles, horizontal isolation pipe sheds, and large pipe sheds inserted on the top of the tunnel. The isolation and protection piles are arranged on one side or both sides of the tunnel to be excavated, the horizontal isolation pipe sheds are arranged on the outside of the isolation and protection piles, and the large pipe shed inserted on the top of the tunnel to be excavated is arranged on the top of the tunnel to be excavated; the reinforcement structure includes support piles and temporary beams, the temporary beams include longitudinal beams and transverse beams, the temporary beams are erected on the support piles, and the temporary beams are arranged under the existing railway facilities above the tunnel to be excavated. According to the second aspect of the embodiment of the present application, a tunnel construction method is provided. This construction method adopts the tunnel reinforcement and protection structure as described above, and its specific construction steps include:

[0007] Establish a construction shaft at the designed starting point of the tunnel and carry out the construction of high-pressure jet grouting piles and ring beams in the shaft;

[0008] The construction of the protective structure, the step of reinforcing the protective structure construction includes the construction of the horizontal isolation pipe shed, the construction of the large pipe shed inserted in the tunnel top and the isolation protection piles according to the installation position of claim 1, and the construction of the support piles in the reinforcement structure below the position where the existing railway facilities need to be emptied;

[0009] Reinforcement structure construction, erecting D-shaped temporary beams on the support piles to support and reinforce the existing railway facilities;

[0010] The tunnel digging construction is to excavate the tunnel after executing the reinforcement structure construction step. The tunnel digging construction adopts a segmented excavation method, first excavating one side of the existing railway facilities, and then excavating the other side of the existing railway facilities above the tunnel to be excavated.

[0011] The tunnel reinforcement and protection structure provided in the embodiment of the present application and the construction method using this structure are used to temporarily guide and modify the existing municipal roads, and traffic is allowed in sections to ensure the operation of the existing railway facilities. During the construction, isolation protection piles + horizontal isolation pipe sheds are used beside the tunnel to block the horizontal and vertical deformation of the soil caused by the tunnel construction, and ensure the stability and safety of the existing railway facilities. A large pipe shed is inserted on the top of the tunnel to ensure the safety of the existing railway facilities on the top of the tunnel and prevent collapse. In addition, a reinforcement method of overhead beams is used for the existing railway facilities to meet the deformation and force requirements of the existing railway facilities. It has been verified that the use of this reinforcement and protection structure and construction method can ensure the stability of the soil above the tunnel and meet the safety of the operation of existing municipal roads and railways. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0013] Figure 1 A schematic diagram of the planar structure of the tunnel reinforcement protection structure provided in an embodiment of the present application;

[0014] Figure 2 A schematic diagram of the elevation structure of the tunnel reinforcement protection structure provided in an embodiment of the present application;

[0015] Figure 3 A schematic diagram of a process flow of a tunnel construction method provided in an embodiment of the present application;

[0016] Figure 4 A schematic diagram of the construction steps of the tunnel reinforcement structure provided in the embodiment of the present application;

[0017] Figure 5 A schematic diagram of the process flow of the tunnel digging construction steps of the tunnel provided in the embodiment of the present application;

[0018] Figure 6 A schematic flow chart of the tunnel cleaning and acceptance steps provided in an embodiment of the present application.

[0019] Reference numerals:

[0020] 1- Construction shaft; 2- Tunnel to be excavated; 3- Isolation and protection piles; 4- Horizontal isolation pipe shed; 5- D-type temporary beam; 6- Support piles; 7- Temporary piers; 8- Crossing plate; 9- Large pipe shed. DETAILED DESCRIPTION

[0021] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0022] In the process of realizing the present application, the inventors found that when constructing a shallow buried tunnel in a location where the tunnel cover is very shallow, an arch effect cannot be formed due to the shallow cover, and the deformation indicators of the existing railways and municipal roads cannot meet the operational safety requirements. The existing reinforcement measures such as grouting in the tunnel combined with the surface longitudinal and transverse beams and 3-5-3 rail-fastening reinforcement measures cannot guarantee the stability of the soil above the tunnel, and cannot meet the operational safety requirements of the existing municipal roads and railways.

[0023] In response to the above problems, the embodiments of the present application provide a tunnel reinforcement protection structure and a tunnel construction method using such a protection structure, so that when tunnel construction is carried out in a location where the tunnel cover is very shallow, the stability of the soil above the tunnel can be ensured, and the safety of existing municipal roads and railway operations can be met.

[0024] In order to clearly illustrate the technical solution of the present application, the embodiment of the present application uses a specific application scenario of a shallow buried dark tunnel passing under an existing railway level crossing for illustration. However, it is worth noting that the technical solution of the present application is not only applicable to this type of application scenario, but can be applied to all shallow buried dark tunnel construction scenarios with shallow cover soil.

[0025] Figure 1 A schematic diagram of the planar structure of the tunnel reinforcement protection structure provided in an embodiment of the present application; Figure 2 A schematic diagram of the elevation structure of the tunnel reinforcement protection structure provided in the embodiment of the present application is shown in FIG. Figure 1 and Figure 2 As shown, the reinforcement and protection structure of the tunnel in the embodiment of the present application includes a protection structure and a reinforcement structure, wherein the protection structure is erected before the tunnel construction, and the protection structure includes isolation protection piles 3, horizontal isolation pipe sheds 4, and a large pipe shed 9 inserted on the top of the tunnel, the isolation protection piles 3 are arranged on one side or both sides of the tunnel 2 to be excavated, the horizontal isolation pipe shed 4 is arranged on the outside of the isolation protection piles 3 (the side of the isolation protection piles 3 close to the tunnel 2 to be excavated is the inner side), and the large pipe shed 9 inserted on the top of the tunnel is arranged on the top of the tunnel 2 to be excavated, and its cross-sectional shape depends on the geological structure requirements, and is usually an arc concentric with the tunnel vault; the reinforcement structure is erected before and during construction, and can support and reinforce the existing railway facilities above the tunnel to be excavated, the reinforcement structure includes supporting piles 6 and temporary beams 5, the temporary beams include longitudinal beams and transverse beams, the longitudinal beams are erected on the supporting piles 6 and / or temporary piers 7, and the existing railway facilities above the tunnel to be excavated are erected on the frame composed of the longitudinal beams and transverse beams.

[0026] After the tunnel is unloaded, the stress state of the surrounding rock changes again, and the pressure at the bottom of the tunnel decreases, causing the bottom to deform and bulge: At the same time, the deformation of the tunnel support structure causes the tunnel surrounding rock to slide into the tunnel. Isolation protection piles are set between the tunnel support structure and the protected buildings. The pile body is inserted into the stable soil layer below the sliding surface, and the thrust of the sliding body is balanced by the resistance of the pile, thereby achieving balance and stability. When the tunnel surrounding rock slides into the tunnel, it is resisted by the pile body, so that the sliding body in front of the pile reaches a stable state, and the displacement deformation of the soil behind the pile is controlled, thereby reducing the deformation of the facilities or buildings around the tunnel, and protecting the existing railway facilities and / or buildings.

[0027] The pipe shed structure is a kind of advanced support structure. The horizontal isolation pipe shed is located on the outside of the isolation protection pile (the side of the isolation protection pile close to the tunnel body is the inside), parallel to the isolation protection pile, and is located in a pre-drilled and installed thick-walled steel pipe with a large inertia moment, which further plays the role of advanced support. On the one hand, the horizontal isolation pipe shed further improves the stiffness of the soil as a whole on the basis of the isolation protection pile, which can prevent the horizontal deformation of the soil. On the other hand, when the tunnel construction disturbs the soil, the soil around the protective isolation pile and the horizontal isolation pipe shed will produce uneven deformation, so that the soil particles are "wedged" against each other, and the soil arch effect appears in the soil layer in a certain area, which effectively prevents the horizontal deformation of the soil behind the pile. Because the horizontal isolation pipe shed is densely arranged, the soil arch effect is obvious. In combination with the protective isolation pile, it can effectively isolate the horizontal displacement of the soil around the tunnel during the construction process.

[0028] The tunnel top inserted large pipe shed 9 is to pre-drill and install thick-walled steel pipes with large inertia moment on the buried arc line of the lining arch ring of the excavated underground tunnel or structural engineering, which plays a temporary advance support role to prevent soil collapse and surface subsidence, so as to ensure the safe operation of excavation and subsequent support technology.

[0029] The D-type beam is suitable for the construction of bridges, culverts and tunnels of existing lines or stations. Its greatest advantage is that it can ensure the operation of existing railway facilities during the construction process. For example, the D-type beam is used to support existing railways or municipal roads, and it can be used for tunnel excavation and construction without interrupting traffic. Due to these characteristics, the D-type beam has been widely used. In order to save design and production costs, the D-type beam is preferred in the embodiments of the present application.

[0030] By adopting the above structure, when shallow buried dark excavation tunnel construction is carried out at a location where the tunnel cover is very shallow, the stability of the soil above the tunnel can be ensured, and the safety of existing municipal roads and railway operations can be met.

[0031] The present application also provides a method for constructing a tunnel using the above-mentioned reinforcement and protection structure. Figure 3 A schematic diagram of a tunnel construction method provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, the specific construction steps include:

[0032] Step 200: Establish a construction shaft 1, establish a construction shaft at the starting point of the tunnel design, and carry out the construction of high-pressure jet grouting piles and ring beams in the shaft;

[0033] Step 300: Construction of protective structure. The step of strengthening the protective structure construction includes the construction of horizontal isolation pipe shed, the construction of large pipe shed inserted in the tunnel top and isolation protection piles according to the erection position of the reinforcement support structure of the tunnel, and the construction of support piles in the reinforcement structure below the position where the existing railway facilities (such as the existing railway) need to be suspended;

[0034] Step 400: reinforcement structure construction, erecting D-shaped temporary beams on the support piles to support and reinforce the existing railway facilities (such as the existing railway);

[0035] Step 500: After executing the reinforcement structure construction step, tunnel excavation construction is carried out. The tunnel construction adopts a segmented excavation method. First, excavation construction is carried out on one side of the existing railway facilities (such as the existing railway), and then excavation construction is carried out on the other side of the existing railway facilities above the tunnel to be excavated.

[0036] Before step 200, step 100 may be performed: pre-construction preparation, which includes temporary traffic diversion and traffic passage in sections; taking the case of passing through a dark tunnel under an existing railway level crossing as an example, temporary traffic diversion is performed according to the plan before construction, and the route is changed when necessary to guide trains to pass at different times;

[0037] After step 500, step 600 may be performed: cleaning and acceptance, that is, cleaning, restoring and accepting the construction site after the construction is completed.

[0038] If the construction scenario is to pass through a tunnel at an existing railway level crossing, the crossing plate 8 needs to be removed and ballast, sleepers, rails, etc. need to be laid before tunnel excavation and erection of the D-type temporary beam. In order to ensure traffic, the removal of the crossing plate 8 needs to be carried out within the skylight point.

[0039] Figure 4 A schematic diagram of the construction steps of the tunnel reinforcement structure provided in the embodiment of the present application is as follows: Figure 4 As shown, further, the reinforcement structure construction steps include:

[0040] Step 401: assembling the temporary beam, that is, using a crane to hoist the longitudinal beam into place, and then connecting it with the cross beam to assemble the D-shaped temporary beam 5;

[0041] Step 402: erecting the temporary beams. After the D-shaped temporary beams 5 are assembled, gradually raise the longitudinal beams so that the D-shaped temporary beams 5 and the supporting piles bear the load.

[0042] Step 403: During the tunnel construction process, the D-type temporary beam is inspected and maintained.

[0043] Taking the shallow buried tunnel under the existing railway level crossing as an example, the specific method of assembling the temporary beam is as follows:

[0044] 1) Use a crane to lift the steel sleepers to both sides of the line. According to the steel sleeper spacing, mark the steel sleeper positions on the line (marked on the rail waist). Before the blocking point, use the slow train interval to adjust the sleeper spacing first, adjust the sleeper spacing, and pull out the excess sleepers, and insert the D-type beam steel sleepers according to the gap. The steel sleepers should be inserted perpendicular to the line, first in the middle and then on both sides.

[0045] 2) To hoist the longitudinal beams, park a large-tonnage crane on one side of the line, hoist the longitudinal beams on one side, and then hoist the longitudinal beams on the other side. After the longitudinal beams are hoisted into place, first connect the steel sleepers at both ends of each temporary beam to the longitudinal beam, and then connect and assemble other steel sleepers.

[0046] 3) After the steel sleepers and the longitudinal beams of the D-type beams are connected and erected as a whole, the longitudinal beams are gradually raised to allow the longitudinal beams to be slowly stressed so that the railway line bears the weight on the longitudinal beams. When raising the longitudinal beams, on-site technicians perform leveling control to control the consistency of the elevation of the four corners of the longitudinal beams and the smoothness of the track line in the construction section.

[0047] The present application embodiment provides specific operation steps for tunnel digging construction. Figure 5 A schematic diagram of the process flow of the tunnel excavation construction steps of the tunnel provided in the embodiment of the present application. Figure 5 As shown, the embodiment of the present application provides tunnel digging construction steps including:

[0048] Step 501: Excavation preparation, determine the tunnel excavation method based on on-site geological factors.

[0049] Use one or a combination of the full section method, step method, middle partition wall method, and double side wall pilot pit method;

[0050] Step 502: grouting the roadbed and foundation. After the grouting of the roadbed and foundation is solidified, a small conduit for grouting the roadbed is reserved;

[0051] Step 503: Tunnel excavation: excavating the tunnel from the construction shaft until the designed mileage.

[0052] The tunnel excavation steps include longitudinal tunnel construction and transverse tunnel construction. If the step method is used, the tunnel faces of the longitudinal tunnel construction need to be staggered by no less than 3m. The transverse tunnel construction steps include:

[0053] Step 504: Initial support construction: after the soil excavation is completed, the initial support protection structure is constructed and erected;

[0054] Step 505: Waterproof layer construction, after the initial support construction is completed, the waterproof layer is laid.

[0055] The waterproof layer construction uses geotextile as a buffer layer and waterproof membrane as a waterproof board, and is laid using a double weld laying method;

[0056] Step 506: Secondary lining construction: After the waterproof layer construction is completed, the secondary lining is applied.

[0057] If the step method is used for construction, the upper step part and the lower step part need to be excavated successively. After each part is excavated, the initial support construction of that part shall be carried out. The waterproof layer construction needs to be constructed from bottom to top. The specific steps are grouting of roadbed and foundation. After the foundation is solidified, a small duct for grouting of railway roadbed is reserved → excavate the soil of the upper step part → carry out the initial support construction of the upper step part → excavate the soil of the lower step part, and apply the lower initial support to close the ring → lay the lower waterproof layer → apply secondary lining to the lower step part → lay the upper waterproof layer and apply the secondary lining of the upper step part → close the secondary lining to form a ring, and backfill and grout.

[0058] Further, the steps of initial support construction include:

[0059] Initial spraying of concrete is carried out after the tunnel excavation is completed; initial spraying of concrete needs to be carried out immediately after the excavation is completed, so as to seal and level the excavation surface in time and prevent the surrounding rock surface from weathering and peeling off.

[0060] After the initial spraying of concrete is completed, the grid steel frame is erected close to the initial spraying concrete surface;

[0061] Re-spray concrete, re-spray concrete after the grid steel frame is erected. Re-spray concrete needs to be carried out after the steel frame is completed and inspected. The thickness of the sprayed concrete is 6 to 8 cm at a time, and it is sprayed 3 times to the designed thickness.

[0062] Furthermore, the grid steel frame is erected by on-site assembly of standard finished units, the finished units are welded together with connecting bars, the grid steel frame is positioned and anchored with locking anchor pipes, and the gap between the grid steel frame and the concrete surface formed after the initial spraying of concrete is filled with concrete blocks.

[0063] Furthermore, the steps of secondary lining construction include: bottom plate reinforcement binding, bottom formwork support, bottom plate concrete pouring, side wall and arch reinforcement binding, side wall and arch formwork support, side wall and arch concrete pouring, and backfill grouting behind the secondary lining. Each sub-step belongs to the existing mature technology and will not be repeated.

[0064] The above-mentioned bottom formwork, side wall and arch formwork adopt combined formwork, and the backfill grouting step behind the second lining is carried out after the bottom plate concrete, side wall and arch concrete reach the designed strength, and the backfill grouting step behind the second lining adopts cement slurry for grouting.

[0065] Figure 6 A schematic diagram of the cleaning and acceptance steps of the tunnel provided in the embodiment of the present application is shown in FIG. Figure 6 As shown, the cleaning and acceptance steps include the steps of restoring existing railway facilities, which include:

[0066] Step 601: Processing the bottom foundation of existing railway facilities;

[0067] Step 602: dismantling the D-type temporary beam;

[0068] Step 603: Restore existing railway facilities;

[0069] Step 604: Clean up the site and inspect the project.

[0070] Furthermore, the bottom foundation treatment of the existing railway facilities includes hollowing out the bottom of the existing railway facilities according to the design elevation; pouring concrete under the existing railway facilities, and leveling the top of the concrete with cement mortar and / or pouring a concrete cushion layer under the existing railway facilities, and then pouring a reinforced concrete base layer on the concrete cushion layer, and the width of the concrete cushion layer and the concrete base layer are both greater than the width of the existing railway facilities.

[0071] Taking the shallow buried tunnel under the existing railway level crossing as an example, the crossing plate and the crossing plate platform need to be reinstalled during the cleaning and acceptance steps. The specific operation process is: treatment of the bottom foundation of the crossing plate and the crossing platform → removal of the line under the D-type temporary beam 5 → removal of the D-type temporary beam 5 → installation of the crossing plate → restoration of the railway track laying → laying of the crossing platform.

[0072] When carrying out the bottom foundation treatment of the crossing slab and the crossing platform, it is necessary to hollow out the bottom of the crossing slab and the crossing platform according to the designed elevation. During this period, the ground railway line (i.e. the existing railway facilities) is completely supported by the D-type temporary beam 5. After the bottom of the crossing slab is hollowed out, C15 concrete is poured, and cement mortar is used to level the top; C15 cushion layer is poured under the crossing platform, and C35 reinforced concrete base layer is poured above the cushion layer. The cushion layer and base layer are 10cm wider than the crossing platform.

[0073] After the foundation treatment of the crossing plate and the crossing platform is completed and the concrete reaches a certain strength, the ground railway line will be dismantled. First, the original rails will be sawed off and lifted out, and then the sleepers will be lifted out.

[0074] After the original rails are removed, the D-type beams are further removed. The removal of the D-type beams is carried out in the reverse order of the installation of the steel beams.

[0075] The crossing plates to be installed are transported from the prefabrication yard to the site one day in advance, and are installed on the cement mortar cushion layer according to the designed position and elevation using a crane and manual labor. During installation, the crossing plates should be kept flat without warping or hanging.

[0076] After the installation of the crossing plate is completed, the railway track is restored and the 50 steel rails with a length of 25m are installed in the groove of the crossing plate and fixed.

[0077] After the railway track is restored, the crossing platform is laid on the concrete base, leaving a 3cm gap between the crossing platform and the crossing plate. Pay attention to the elevation control during installation to ensure that vehicles can pass smoothly at the junction of the crossing plate, crossing platform and Li Tian Road.

[0078] Final acceptance will be carried out after everything has been restored to its original state.

[0079] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0080] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0081] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0082] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0083] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these 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 also intended to include these modifications and variations.

Claims

1. A tunnel construction method, characterized in that: The tunnel reinforcement and protection structure adopted in the tunnel construction method includes: The protective structure includes isolation protection piles, horizontal isolation pipe sheds, and tunnel top inserted large pipe sheds. The isolation protection piles are arranged on one side or both sides of the tunnel to be excavated, the horizontal isolation pipe shed is arranged on the outside of the isolation protection piles, and the tunnel top inserted large pipe shed is arranged on the top of the tunnel to be excavated; A reinforcement structure, the reinforcement structure includes support piles and temporary beams, the temporary beams include longitudinal beams and transverse beams, the temporary beams are erected on the support piles, and the temporary beams are arranged under the existing railway facilities above the tunnel to be excavated; Construction methods include: Establish a construction shaft at the designed starting point of the tunnel and carry out the construction of high-pressure jet grouting piles and ring beams in the shaft; The reinforcement and protection structure construction includes the steps of carrying out the construction of the horizontal isolation pipe shed, the construction of the large pipe shed inserted on the top of the tunnel, and the construction of isolation and protection piles, and the construction of support piles in the reinforcement structure below the position where the existing railway facilities need to be elevated; Reinforcement structure construction, erecting temporary beams on the support piles to support and reinforce the existing railway facilities; The tunnel excavation construction is to excavate the tunnel after the reinforcement structure construction step is performed. The tunnel construction adopts a segmented excavation method, first excavating one side of the existing railway facilities, and then excavating the other side of the existing railway facilities above the tunnel to be excavated. The steps of tunnel excavation construction specifically include: Excavation preparation: determine the tunnel excavation method based on on-site geological factors, using one or a combination of the full-section method, step method, middle partition wall method, and double-side wall pilot tunnel method; Grouting of roadbed and foundation. After the grouting of roadbed and foundation is solidified, a small conduit for grouting of roadbed is reserved; Tunnel excavation, excavation of the tunnel from the construction shaft to the designed mileage, tunnel excavation steps include tunnel longitudinal construction and tunnel transverse construction, of which tunnel transverse construction includes: Initial support construction: after the soil excavation is completed, the initial support protection structure is constructed and erected; Waterproof layer construction: laying of waterproof layer after the initial support construction is completed; Secondary lining construction: secondary lining construction is carried out after the waterproof layer construction is completed.

2. The tunnel construction method according to claim 1, characterized in that: The reinforcement structure construction steps include: Assembling the temporary beam, that is, using a crane to lift the longitudinal beam into place, and then connect it with the cross beam to assemble the temporary beam; Erecting the temporary beams, after the temporary beams are assembled, gradually raising the longitudinal beams so that the temporary beams and the supporting piles bear the load; During the tunnel construction process, the temporary beams are inspected and maintained.

3. The tunnel construction method according to claim 2, characterized in that: In the step of erecting the temporary beam, when raising the longitudinal beam, the on-site technicians perform leveling control.

4. The tunnel construction method according to claim 1, characterized in that: The steps of the initial support construction include: Initial concrete spraying: Initial concrete spraying is carried out after tunnel excavation is completed; After the initial spraying of concrete is completed, the grid steel frame is erected close to the initial spraying concrete surface; Re-spray concrete. Re-spray concrete after the grid steel frame is erected.

5. The tunnel construction method according to claim 4, characterized in that: The grid steel frame is erected by on-site assembly of standard finished units, the finished units are welded together by connecting bars, the grid steel frame is positioned and anchored by locking anchor pipes, and the gap between the grid steel frame and the concrete surface formed after the initial spraying of concrete is filled with concrete blocks.

6. The tunnel construction method according to claim 4, characterized in that: In the re-spraying concrete step, multiple re-spraying is performed to reach the designed thickness.

7. The tunnel construction method according to claim 4, characterized in that: The waterproof layer construction uses geotextile as a buffer layer and waterproof membrane as a waterproof board, and is laid using a double-weld laying method.

8. The tunnel construction method according to claim 4, characterized in that: The steps of the secondary lining construction include: bottom plate reinforcement binding, bottom formwork support, bottom plate concrete pouring, side wall and arch reinforcement binding, side wall and arch formwork support, side wall and arch concrete pouring, and backfill grouting behind the secondary lining.

9. The tunnel construction method according to claim 8, characterized in that: The bottom formwork, side wall and arch formwork adopt combined formwork, and the backfill grouting step behind the second lining is carried out after the bottom plate concrete, side wall and arch concrete reach the designed strength. The backfill grouting step behind the second lining adopts cement slurry for grouting.

10. The tunnel construction method according to claim 1, characterized in that: The construction method also includes the following steps: Preparation before construction, the steps of preparation before construction include temporary traffic diversion and traffic passage in sections; Cleaning and acceptance means cleaning, restoring and accepting the construction site after the construction is completed.

11. The tunnel construction method according to claim 10, characterized in that: The cleaning and acceptance steps include the steps of restoring existing railway facilities, and the steps of restoring existing railway facilities include: treating the bottom foundation of existing railway facilities, removing temporary beams, restoring the existing railway facilities, cleaning the site, and project acceptance.

12. The tunnel construction method according to claim 11, characterized in that: The bottom foundation treatment of the existing railway facilities includes hollowing out the bottom of the existing railway facilities according to the designed elevation; pouring concrete under the existing railway facilities, leveling the top of the concrete with cement mortar and / or pouring a concrete cushion layer under the existing railway facilities, and then pouring a reinforced concrete base layer on the concrete cushion layer, and the width of the concrete cushion layer and the concrete base layer are both greater than the width of the existing railway facilities.

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