Method for converting from benching construction to double-side-wall heading construction in a tunnel

Abstract

The application relates to a conversion method from bench method construction to double-side-wall heading method construction in a tunnel, and relates to the technical field of tunnel excavation, which comprises the following construction steps: S1, excavating an arc-shaped heading, and excavating the arc-shaped heading along a tunnel arch contour; S2, detecting a soil sample; S3, selecting an excavation method, and selecting the bench method or the double-side-wall heading method for excavation according to the soil condition, so as to complete sectional excavation of the tunnel; and S4, repeating the above steps to complete the whole tunnel excavation. According to the application, the arc-shaped heading is excavated first, then the excavation method is selected after the soil condition is detected, so as to realize sectional excavation of the tunnel, and then the above steps are continuously performed to complete the whole tunnel excavation, so that the construction progress and construction safety are simultaneously improved.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel excavation, and in particular to a method for converting a step method of construction into a double-sidewall pilot tunnel method of construction in a tunnel. Background Art

[0002] Tunnel excavation methods include shield method, drilling and blasting method, and combined construction method of drilling and blasting method and shield method. Therefore, different excavation methods can be used according to the length of the tunnel and geological conditions.

[0003] Among them, the main construction methods of drilling and blasting include full-section method, step method, double-side wall pilot tunnel method, etc. The excavation speed of these construction methods slows down successively, but the cost increases successively, and the safety increases successively; the advantage of the full-section method is that the construction is convenient and the construction progress is fast. The disadvantage is that it has strict requirements on geological conditions and requires good self-stability of the surrounding rock; the double-side wall pilot tunnel method is safe to construct and is suitable for excavating large-section tunnels and suitable for surrounding rocks with unstable rock masses, but the speed is slow and the cost is high.

[0004] Since the cross-section size and geological conditions encountered during the excavation process are constantly changing, the use of a construction method can only meet one of the requirements of improving construction progress or improving construction safety, but not both. Summary of the Invention

[0005] In order to improve both construction progress and construction safety, the present application provides a method for converting the step method construction to the double-side wall pilot tunnel method construction in a tunnel.

[0006] The method for converting tunnel construction from the step method to the double-sidewall pilot method in this application adopts the following technical solutions:

[0007] The conversion method from the step method to the double-sidewall pilot method in a tunnel includes the following construction steps:

[0008] S1. Excavate a curved pilot pit along the arched contour of the tunnel;

[0009] S2. Testing soil samples to determine the soil quality of the excavated soil;

[0010] S3. Select the excavation method, either the step method or the double-sidewall pilot method, depending on the soil conditions, to complete the tunnel excavation in sections.

[0011] S4. Repeat the above steps to complete the entire tunnel excavation.

[0012] By adopting the above technical solution, an arc-shaped pilot pit is first excavated along the arch profile of the tunnel, and then the excavated soil is tested to obtain the soil conditions. The excavation method is selected according to the soil conditions. If the self-stability is good, the step method is selected for excavation. Otherwise, the double-side wall pilot pit method is selected for excavation. In this way, the tunnel is excavated in sections, and then the above steps are continued to complete the excavation of the entire tunnel. In this way, the appropriate excavation method is selected according to the soil conditions, thereby improving the construction progress and construction safety at the same time.

[0013] Optionally, after the excavation of S1, the arc-shaped pilot pit is initially supported by a supporting mechanism, and the supporting mechanism includes:

[0014] A steel cage, wherein the steel cage is fixedly mounted on the arc-shaped guide pit by an anchor cable, and the steel cages on two adjacent support mechanisms are connected together by a fixing assembly;

[0015] A concrete layer is formed by spraying concrete onto the reinforcement cage.

[0016] By adopting the above technical solution, the steel cage is pressed against the side wall of the arc-shaped guide pit, and then the steel cage is fixed to the arc-shaped guide pit by anchor cables. Concrete is then sprayed onto the steel cage to form a concrete layer to support the arc-shaped guide pit, and the fixing assembly fixes the two adjacent steel cages together, thereby further improving the supporting effect of the support mechanism on the arc-shaped guide pit and improving the construction safety of the tunnel.

[0017] Optionally, the fixing component includes:

[0018] A fixed pipe is provided on the steel cage and contacts the bottom wall of the arc-shaped guide pit.

[0019] a retaining ring, the retaining ring being arranged on the inner side wall of the fixed tube;

[0020] a baffle, the baffle being rotatably disposed on the inner side wall of the fixed tube and being pressed against the baffle ring under the action of gravity and being used to separate the fixed tube into two independent separation chambers, the baffle being further provided with a magnet ring adsorbed on the baffle ring;

[0021] A fixing rod, both ends of which are plugged into the fixing tubes and abut against baffles located in the two fixing tubes. When the fixing rod is plugged into the fixing tubes, the baffles can be pushed to move so that the fixing rod passes through the two separation cavities. When the concrete layer is poured, the fixing rod and the fixing tubes are fixedly connected together.

[0022] By adopting the above technical solution, when pouring the outermost steel cage, the baffle is pressed against the baffle ring under the action of gravity and the adsorption of the magnet ring to separate the fixed pipe into two independent separation chambers, so that concrete will not enter the separation chamber near the bottom wall of the arc guide pit. When installing the next steel cage, the fixing rod is first inserted into the fixing pipe, and the fixing rod pushes the baffle and passes through the two separation chambers, so that the fixing rod moves into the interior of the steel cage. After the steel cage is fixed and installed by the anchor cable, the fixing rod is pulled to be inserted into the fixing pipe of the previous steel cage, and the fixing rod is away from the baffle. The baffle is pressed against the baffle ring under the action of gravity, and the two ends of the fixing rod are respectively in conflict with the two baffles. When pouring the concrete layer, the concrete layer fixes the fixing rod and the two fixed pipes together, thereby fixing the two steel cages together. The method of connecting the next fixing rod is the same, thereby achieving multiple steel cages fixedly connected together, thereby improving the support effect of the support mechanism on the tunnel and improving the safety of tunnel construction.

[0023] Optionally, the step method includes the following steps:

[0024] S1. Continue excavating along the tunnel arch profile to complete the excavation of the entire tunnel arch profile;

[0025] S2. Set up a support structure to support the newly excavated part and connect it with the support structure located in the arc-shaped pilot pit;

[0026] S3. Obtain subsequent excavation data based on the test results, where the excavation data includes the number of excavation steps and the excavation length;

[0027] S4. Excavate the steps in sections according to the excavation data. The excavation follows the principle of excavating the upper part first and then the lower part.

[0028] By adopting the above technical solution, excavation is continued along the tunnel contour to complete the excavation of the entire tunnel arch contour, and then a support mechanism is set up to support the newly excavated part, and then excavation is carried out according to the design, so as to excavate the tunnel in sections. Therefore, after excavating the arch contour first, the support mechanism is set up and connected with the support mechanism in the arc-shaped pilot pit to support the tunnel, and finally the steps are excavated, thereby improving the construction safety of the tunnel.

[0029] Optionally, an inclined connecting section is formed between two adjacent steps, and a supporting mechanism is set up on the connecting section to form a supporting plane, and the supporting plane is convenient for excavating machinery or equipment for transporting soil to pass through.

[0030] By adopting the above technical solution, the inclined connecting section connects the two steps together, thereby improving the stability of the steps after excavation and improving the construction safety of the tunnel; and the supporting mechanism is set up on the connecting section to form a supporting plane, which facilitates the operation of the equipment and thus improves the construction progress of the tunnel.

[0031] Optionally, the supporting mechanism includes:

[0032] A plurality of support plates, wherein the support plates are mounted on the connecting section, and connecting blocks for connection are installed on two adjacent support plates;

[0033] Insertion rods are arranged on the support rods and are each provided with a plurality of rods and inserted into the connecting section for positioning.

[0034] By adopting the above technical solution, multiple support plates are set up on the connecting section and spliced ​​together, and then the connecting block is clamped and installed on two adjacent support plates, and the insertion rod is inserted into the connecting section for positioning, thereby improving the stability of the equipment passing through the support plate, thereby facilitating the passage of the equipment and improving the construction safety of the tunnel.

[0035] Optionally, drainage ditches for drainage are provided in the tunnel and on both sides of the connecting section, and a plurality of squeezing rollers are evenly arranged on the support plate. After the squeezing rollers squeeze the connecting section, drainage grooves are formed to guide the accumulated water into the drainage ditches.

[0036] By adopting the above technical solution, after the squeezing roller squeezes to form the drainage groove, the drainage groove blocks the movement of the squeezing roller, thereby further improving the stability of the equipment when passing through the support plate. At the same time, the accumulated water in the section flows into the drainage groove, and then the accumulated water flows into the drainage ditch for collection. At the same time, after the insertion rod is inserted into the connecting section, the accumulated water flows out through the insertion rod, thereby facilitating the collection of the accumulated water generated during excavation, reducing the probability of the section collapsing due to accumulated water, thereby improving the construction safety of the tunnel.

[0037] Optionally, the double-sidewall pilot pit method includes the following steps:

[0038] S1. Excavate the right pilot pit and install the support mechanism. Excavate the section located on the right side below the curved pilot pit along the tunnel arch profile and connect it to the bottom of the curved pilot pit. Then install the support mechanism for support. Finally, continue excavation to complete the excavation of the right pilot pit.

[0039] S2: Excavate the left pilot pit and install the support mechanism. Use the same method as S1 to excavate and install the support mechanism on the left side below the arc-shaped pilot pit.

[0040] S3. Excavate the middle pilot pit. Excavate the middle pilot pit to complete the tunnel excavation.

[0041] Optionally, a plurality of protective tubes are detachably connected to the tunnel, and the plurality of protective tubes extend outside the tunnel. A life-saving bag containing life-saving items is fixedly installed on the inner wall of each protective tube and above the axis of the protective tube.

[0042] By adopting the above technical solution, when the tunnel collapses, debris accumulates on the protective pipe, and the workers can enter the protective pipe and then move toward the outside of the tunnel to escape. When the workers are trapped in the protective pipe, they can open the life-saving bag and take out life-saving items to save themselves, thereby improving the construction safety of the tunnel.

[0043] In summary, this application includes at least one of the following beneficial technical effects:

[0044] By first excavating an arc-shaped pilot pit and then selecting an excavation method after testing the soil conditions, the tunnel can be excavated in sections, and then the above steps are continued to complete the excavation of the entire tunnel, thereby improving both construction progress and construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the structure when using the bench excavation method in this application;

[0046] Figure 2 It is a schematic diagram of the structure of the steel cage and fixing components in this application;

[0047] Figure 3 is a schematic structural diagram of the fixing assembly in the present application, wherein two fixing tubes are cut away;

[0048] Figure 4 It is a schematic diagram of the structure of the support mechanism in this application, in which a support plate and components on the support plate are exploded;

[0049] Figure 5 This is a schematic diagram of the structure when excavating using the double-side wall pilot tunnel method in this application;

[0050] Figure 6 This is a schematic diagram of the protective tube and its internal structure in this application, in which two protective tubes and the plug-in tube are cut away.

[0051] Figure numerals: 11. Arc guide pit; 12. Right auxiliary guide pit; 13. Left auxiliary guide pit; 14. Step; 15. Connecting section; 16. Right guide pit; 17. Left guide pit; 2. Support mechanism; 21. Steel cage; 22. Concrete layer; 3. Fixing assembly; 31. Fixing pipe; 32. Retaining ring; 33. Baffle; 34. Fixing rod; 35. Mounting hole; 36. Accommodating hole; 38. Partition chamber; 4. Support mechanism; 41. Support plate; 42. Insert rod; 43. Snap-in groove; 44. Connecting block; 45. Extrusion roller; 46. Drainage trough; 47. Drainage ditch; 5. Lifting assembly; 51. Protective pipe; 52. Plug-in pipe; 53. Life-saving kit; 54. Plug-in groove. DETAILED DESCRIPTION

[0052] The following is a further detailed description of 1-6 of this application in conjunction with the accompanying drawings.

[0053] The embodiments of the present application disclose a method for converting the step method construction to the double-sidewall pilot tunnel method construction in a tunnel.

[0054] Reference Figure 1 The conversion method from the step method to the double-sidewall pilot method in the tunnel includes the following construction steps:

[0055] S1. Excavate an arc-shaped pilot pit 11 along the arch profile of the tunnel. The vertical plane passing through the two ends of the tunnel and the axis is a mirror plane. The arc-shaped pilot pit 11 includes two arc-shaped surfaces symmetrical about the mirror plane, and the arc-shaped surface is located at the top of the tunnel arch profile. After the arc-shaped pilot pit 11 is excavated, a support mechanism 2 is set up to provide preliminary support for the arc-shaped pilot pit 11.

[0056] S2. Testing soil samples to determine the soil quality of the excavated soil;

[0057] S3. Select the excavation method, either the step method or the double-sidewall pilot method, depending on the soil conditions, to complete the tunnel excavation in sections.

[0058] S4. Repeat the above steps to complete the entire tunnel excavation.

[0059] Reference Figure 1 and Figure 2The support mechanism 2 includes a steel cage 21 and a concrete layer 22. The steel cage 21 is a cage structure formed by binding multiple steel bars, and the steel cage 21 is fixedly installed on the side wall of the arc guide pit 11 by anchor cables. The anchor cables pass through the steel cage 21 and are fixedly installed on the side wall of the arc guide pit 11. The steel cage 21 is arc-shaped and fits the side wall of the arc guide pit 11, so as to support the arc guide pit 11, and the two ends of the steel cage 21 are pressed against the arc guide pit 11 for positioning. When the tunnel is excavated in sections, the steel cage 21 on the latter section of the arc guide pit 11 is connected to the steel cage 21 on the previous section of the arc guide pit 11 through a fixing assembly 3; the concrete layer 22 is formed by spraying concrete onto the steel cage 21, so as to support and position the arc guide pit 11.

[0060] Reference Figure 2 and Figure 3 A plurality of fixing components 3 are arranged at arc-shaped intervals along the steel cage 21 , and the fixing components 3 include a fixing tube 31 , a retaining ring 32 , a baffle 33 , and a fixing rod 34 .

[0061] Reference Figure 1 and Figure 2 The fixed pipe 31 is fixedly installed inside the steel cage 21 and its axis is parallel to the axis of the tunnel, and one end of the fixed pipe 31 is in conflict with the inner bottom wall of the arc-shaped pilot pit 11.

[0062] Reference Figure 1 and Figure 3 A mounting hole 35 is coaxially opened on the inner wall of the fixed tube 31 and located in the middle position, and a receiving hole 36 connected to the mounting hole 35 is opened on the inner wall of the fixed tube 31 and located on the side of the inner bottom wall of the arc-shaped guide pit 11 close to the mounting hole 35, and the receiving hole 36 is located above the axis of the fixed tube 31.

[0063] Reference Figure 1 and Figure 3 The retaining ring 32 is coaxially fixedly installed in the mounting hole 35, and the inner diameter of the retaining ring 32 is the same as the inner diameter of the fixed tube 31. The baffle 33 is disc-shaped and the top end is rotatably installed on the side wall of the accommodating hole 36. The baffle 33 is pressed against the retaining ring 32 under the action of gravity. At the same time, a magnet ring that can be adsorbed on the retaining ring 32 is clamped and installed on the side wall of the baffle 33, so as to realize the separation of the fixed tube 31 into two independent separation chambers 38.

[0064] Reference Figure 2 and Figure 3 The two ends of the fixing rod 34 are inserted and installed on the fixing tubes 31 located on the two adjacent steel cages 21, and the two ends of the fixing rod 34 can contact the side walls on the opposite side of the two baffles 33. The fixing rod 34 pushes the baffle ring 32 to move the baffle ring 32 into the accommodating hole 36, and the fixing rod 34 can pass through the two partition chambers 38 and move between the two baffles 33. After the two baffles 33 move back under the action of gravity, they can contact the fixing rod 34.

[0065] Reference Figure 1 and Figure 2 , the steel cage 21 is installed on the arc guide pit 11 and then fixed by anchor cables, and then concrete is sprayed onto the steel cage 21 to form a concrete layer 22.

[0066] Reference Figure 1 and Figure 3 The baffle 33 blocks the concrete from entering the separation cavity 38 near the bottom wall of the arc-shaped guide pit 11.

[0067] Reference Figure 2 and Figure 3 When installing the next steel cage 21, first insert the fixing rod 34 into the fixing tube 31, push the fixing rod 34 to push the baffle 33 to move into the accommodating hole 36, so that the fixing rod 34 passes through the two separation cavities 38, so that the fixing rod 34 moves into the steel cage 21.

[0068] Reference Figure 1 and Figure 2 , the steel cage 21 is fixedly installed on the arc guide pit 11.

[0069] Reference Figure 2 and Figure 3 , then pull the fixing rod 34 and insert it into the previous fixing tube 31, so that the fixing rod 34 contacts the baffle 33 located in the previous fixing tube 31, and the baffle 33 located in the rear fixing tube 31 is pressed and adsorbed on the baffle ring 32 under the action of gravity, and then concrete is sprayed. Therefore, the concrete fixes the steel cage 21, the fixing tube 31 and the fixing rod 34 together, thereby fixing the two steel cages 21 together.

[0070] The step method includes the following construction steps:

[0071] Reference Figure 1 and Figure 2 S1. Continue excavating along the tunnel arch profile, excavating the tunnel below the arc-shaped pilot pit 11 to obtain an arc-shaped left auxiliary pilot pit 13 and a right auxiliary pilot pit 12. The left auxiliary pilot pit 13 is located on the left side of the arc-shaped pilot pit 11, and the right auxiliary pilot pit 12 is located on the right side of the arc-shaped pilot pit 11. At the same time, the left auxiliary pilot pit 13, the right auxiliary pilot pit 12 and the arc-shaped pilot pit 11 together constitute the tunnel arch profile, thereby completing the excavation of the entire tunnel arch profile;

[0072] S2. Setting up the support mechanism 2 to support the newly excavated portion. After the excavation of the left auxiliary pilot pit 13 is completed, the support mechanism 2 is set up for support. After the excavation of the right auxiliary pilot pit 12 is completed, the support mechanism 2 is also set up for support. At the same time, when pouring concrete in the left and right auxiliary pilot pits 13 and 12, the concrete is poured together with the concrete layer 22 in the arc-shaped pilot pit 11, thereby supporting the entire arch profile of the tunnel.

[0073] S3. Obtain subsequent excavation data based on the test results, the excavation data including the number of excavation steps 14 and the excavation length;

[0074] S4. Excavate the steps 14 in sections according to the excavation data. First, excavate the two sides of the concrete layer 22 to form a transportation space for the transport vehicles to pass through, and then excavate the steps 14. At the same time, excavation follows the principle of excavating the upper part first and then the lower part.

[0075] Reference Figure 1 and Figure 4 During excavation, an inclined connecting section 15 is formed between two adjacent steps 14 in the height direction. The connecting section 15 covers the entire step 14, and multiple connecting sections 15 are connected together. A supporting mechanism 4 is set up on the connecting section 15 to form a supporting plane, and the supporting plane is for the equipment for excavation and transportation of soil to pass through.

[0076] Reference Figure 1 and Figure 4 The support mechanism 4 includes multiple support plates 41 and insertion rods 42. The multiple support plates 41 are spliced ​​together and placed on the upper surface of the connecting section 15. The support plates 41 are in the shape of a cube and a snap-in groove 43 is provided on the upper surface. There are four snap-in grooves 43 and they are located at the four sides of the support plates 41 and are respectively connected to the four side walls of the support plates 41. At the same time, the cross-section of the snap-in groove 43 is T-shaped; a connecting block 44 is snap-fitted and installed on the snap-in grooves 43 of two adjacent support plates 41, so the connecting block 44 is used to fix the two adjacent support plates 41 together, and at the same time, multiple support plates 41 cover the entire connecting section 15.

[0077] Reference Figure 1 and Figure 4 , the insertion rods 42 are fixedly installed on the lower surface of the support plate 41 and are provided with multiple rods. At the same time, the insertion rods 42 are inserted into the connecting section 15 for positioning; drainage ditches 47 are opened on the bottom wall of the tunnel and on one side close to the two ends of the concrete layer 22, and multiple squeezing rollers 45 are fixedly installed at intervals on the lower surface of the support plate 41, and the cross-section of the squeezing rollers 45 is in a semicircular arc state. At the same time, the squeezing rollers 45 squeeze the connecting section 15 to form a drainage groove 46. At the same time, the drainage groove 46 is connected to the side wall of the connecting section 15 close to the drainage ditch 47. Therefore, the drainage groove 46 is used to guide the accumulated water into the drainage ditch 47, so as to achieve the discharge of the accumulated water.

[0078] Reference Figure 5 , double side wall pilot tunnel excavation method includes the following steps:

[0079] S1, excavate the right pilot pit 16 and install the support mechanism 2, excavate the section located on the right side below the curved pilot pit 11 along the tunnel arch profile to obtain the right auxiliary pilot pit 12, and connect the right auxiliary pilot pit 12 to the bottom end of the curved pilot pit 11, then install the support mechanism 2 to support the right auxiliary pilot pit 12, and finally continue excavation to complete the excavation of the right pilot pit 16;

[0080] S2, excavate the left pilot pit 17 and install the support mechanism 2. Use the same method as S1 to excavate the left side below the arc-shaped pilot pit 11 to obtain the left auxiliary pilot pit 13. Then install the support mechanism 2 in the left auxiliary pilot pit 13. Finally, continue excavating to complete the excavation of the left pilot pit 17.

[0081] S3. Excavate the middle pilot pit. Excavate the middle pilot pit to complete the tunnel excavation.

[0082] Reference Figure 5 and Figure 6 After excavation, multiple protective tubes 51 are fixedly installed on the bottom wall of the tunnel and on one side close to the two ends of the support mechanism 2, and the axis of the protective tube 51 is parallel to the axis of the tunnel. At the same time, a plug-in tube 52 is coaxially fixedly installed on one end of the protective tube 51, and a plug-in groove 54 that can be plugged into the plug-in tube 52 is coaxially opened at the other end of the protective tube 51, and the plug-in tube 52 and the protective tube 51 have the same inner diameter. At the same time, the plug-in tube 52 on the rear protective tube 51 is plugged into the plug-in groove 54 on the front protective tube 51, so as to realize the detachable connection of multiple protective tubes 51, and the multiple protective tubes 51 are spliced ​​and extended out of the tunnel.

[0083] Reference Figure 5 and Figure 6 A life-saving bag 53 is fixedly installed on the inner wall of each protective tube 51 and above the axis of the protective tube 51. The life-saving bag 53 contains life-saving items, such as food, water, and life-saving medicines. A mark is painted on the outer wall of the protective tube 51, which is used to mark the position of the life-saving items. After the protective tube 51 is installed, the life-saving items are located above the axis of the protective tube 51, reducing the probability of the life-saving items being eroded by water flow.

[0084] Reference Figure 6 When the tunnel collapses and accumulates on the protection tube 51, the staff can enter the protection tube 51 and then move to the outside of the tunnel through the protection tube 51 to escape. When trapped in the protection tube 51, the staff can use the items in the life-saving bag 53 to save themselves.

[0085] The working principle of the embodiment of this application is as follows:

[0086] First, excavation is carried out along the arch profile of the tunnel to obtain an arc-shaped pilot pit 11, and then the soil conditions are tested. According to the test data results, the step method and the double-side wall pilot pit method are selected for excavation. Then, the above steps are repeated to complete the excavation of the entire tunnel. Therefore, the appropriate method can be selected for tunnel excavation according to the situation, thereby improving the construction progress and construction safety at the same time.

[0087] During the step excavation, first continue to excavate along the arch profile of the tunnel to obtain the left auxiliary guide pit 13 and the right auxiliary guide pit 12. After the excavation is completed, the support mechanism 2 is installed for support, and then the remaining part of the tunnel is excavated using the up-first-down method to form a connecting section 15. Then the support plate 41 is set on the connecting section 15, and the plug rod 42 is plugged and installed on the connecting section 15, and the squeezing roller 45 squeezes the connecting section 15 to form a drainage groove 46. The accumulated water is discharged into the drainage ditch 47 through the drainage groove 46 for drainage. Therefore, multiple support plates 41 are connected together to form a support plane. The support plane is convenient for equipment to pass through. Finally, the excavation of the tunnel is completed, thereby improving the construction safety of the tunnel.

[0088] When excavating using the double-side wall pilot tunnel method, first continue excavating along the tunnel arch profile to obtain the left auxiliary pilot tunnel 13, then install the support mechanism 2 to support the left auxiliary pilot tunnel 13, then continue excavating to obtain the left pilot tunnel 17, and then excavate the right pilot tunnel 16. The excavation method is the same as the excavation method of the left pilot tunnel 17. Finally, excavate the middle pilot tunnel to complete the excavation of the tunnel. At the same time, multiple protection pipes 51 are fixed to the bottom wall of the tunnel. Therefore, when the tunnel collapses, it accumulates on the protection pipe 51, and the staff can enter the protection pipe 51 to escape. When trapped in the protection pipe 51, the staff can use the items in the life-saving bag 53 to save themselves, thereby improving the construction safety of the tunnel.

[0089] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for converting tunnel construction from the step method to the double-sidewall pilot tunnel method, characterized by: The construction steps include: S1, excavating an arc-shaped pilot pit (11), excavating an arc-shaped pilot pit (11) along the arch profile of the tunnel; S2. Testing soil samples to determine the soil quality of the excavated soil; S3. Select the excavation method, either the step method or the double-sidewall pilot method, depending on the soil conditions, to complete the tunnel excavation in sections. S4, repeat the above steps to complete the entire tunnel excavation; After the excavation of S1, the arc-shaped pilot pit (11) is initially supported by a support mechanism (2), wherein the support mechanism (2) comprises: A steel cage (21), wherein the steel cage (21) is fixedly mounted on the arc-shaped guide pit (11) via an anchor cable, and the steel cages (21) located on two adjacent support mechanisms (2) are connected together via a fixing assembly (3); a concrete layer (22), the concrete layer (22) being formed by spraying concrete onto the steel cage (21); The fixing assembly (3) comprises: A fixed pipe (31), wherein the fixed pipe (31) is arranged on the steel cage (21) and contacts the bottom wall of the arc-shaped guide pit (11). a retaining ring (32), the retaining ring (32) being arranged on the inner side wall of the fixed tube (31); a baffle (33) rotatably disposed on the inner side wall of the fixed tube (31) and pressed against the baffle ring (32) under the action of gravity and used to separate the fixed tube (31) into two independent separation chambers (38); the baffle (33) is further provided with a magnet ring adsorbed on the baffle ring (32); A fixing rod (34), both ends of which are plugged into and installed on the fixing tubes (31) and which are in contact with baffles (33) located in the two fixing tubes (31). When the fixing rod (34) is plugged into and installed in the fixing tubes (31), the baffles (33) can be pushed to move so that the fixing rod (34) passes through the two separation chambers (38). When the concrete layer (22) is poured, the fixing rod (34) and the fixing tubes (31) are fixedly connected together.

2. The method for converting tunnel construction from the step method to the double-sidewall pilot method according to claim 1, characterized in that: The step method comprises the following steps: S1. Continue excavating along the tunnel arch profile to complete the excavation of the entire tunnel arch profile; S2, setting up a support mechanism (2) to support the newly excavated portion and connecting it to the support mechanism (2) located in the arc-shaped pilot pit (11); S3, designing and obtaining subsequent excavation data according to the detection results, the excavation data including the number of excavation steps (14) and the excavation length; S4. Excavate the steps (14) in sections according to the excavation data. Excavation follows the principle of excavating the upper part first and then the lower part.

3. The method for converting tunnel construction from the step method to the double-sidewall pilot method according to claim 2, characterized in that: An inclined connecting section (15) is formed between two adjacent steps (14), and a supporting mechanism (4) is mounted on the connecting section (15) to form a supporting plane, wherein the supporting plane is convenient for excavating machinery or soil transporting equipment to pass through.

4. The method for converting tunnel construction from the step method to the double-sidewall pilot method according to claim 3, characterized in that: The supporting mechanism (4) comprises: A plurality of support plates (41), wherein the support plates (41) are mounted on the connecting section (15), and connecting blocks (44) for connection are installed and plugged into two adjacent support plates (41); Insertion rods (42), the insertion rods (42) are arranged on the support rod and are each provided with a plurality of and inserted into the connecting section (15) for positioning.

5. The method for converting tunnel construction from the step method to the double-sidewall pilot method according to claim 4, characterized in that: Drainage ditches (47) for drainage are provided in the tunnel and on both sides of the connecting section (15). A plurality of squeezing rollers (45) are evenly arranged on the support plate (41). After squeezing the connecting section (15), the squeezing rollers (45) can form drainage grooves (46) that guide the accumulated water into the drainage ditches (47).

6. The method for converting tunnel construction from the step method to the double-sidewall pilot method according to claim 1, characterized in that: The double-sidewall pilot pit method comprises the following steps: S1, excavating the right pilot pit (16) and installing the supporting mechanism (2), excavating the section located on the right side below the arc-shaped pilot pit (11) along the tunnel arch profile and making it connected with the bottom end of the arc-shaped pilot pit (11), then installing the supporting mechanism (2) for support, and finally continuing to excavate the right pilot pit (16); S2, excavating the left pilot pit (17) and installing the support mechanism (2), using the same method as S1 to excavate and install the support mechanism (2) on the left side below the arc-shaped pilot pit (11); S3. Excavate the middle pilot pit. Excavate the middle pilot pit to complete the tunnel excavation.

7. The method for converting tunnel construction from the step method to the double-sidewall pilot method according to claim 6, characterized in that: A plurality of protective tubes (51) are detachably connected to the tunnel, and the plurality of protective tubes (51) extend outside the tunnel. A life-saving bag (53) containing life-saving items is fixedly installed on the inner side wall of each protective tube (51) and above the axis of the protective tube (51).

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