Tunnel variable-line-spacing section excavation construction method

Abstract

The present application relates to the technical field of tunnel construction, and particularly relates to a tunnel variable line interval section excavation construction method, step S1, a preceding hole is advanced by using a bench method, step S2, a trailing hole lags behind the preceding hole and advances by using the bench method, a lag length is matched with a variable line interval section length; step S3, the preceding hole and the trailing hole are synchronously advanced, step S4, the trailing hole is advanced by using a micro-disturbance blasting mode in the variable line interval section, step S5, the trailing hole converges into the preceding hole, a support arch corresponding to a profile of a junction section is arranged at the junction section of the preceding hole and the trailing hole, step S6, junction section excavation is completed, the preceding hole and the trailing hole are completely converged, and then the trailing hole is continuously advanced until tunnel excavation is completed. Through staggered construction of the preceding hole and the trailing hole, the preceding hole is constructed and primary support is performed, and then the trailing hole is converged, so that interference on the variable line interval section in the construction process is reduced, and support pipe sheds are staggered to form a support curtain, so that stability of the construction is ensured.

Description

Technical Field

[0001] This invention belongs to the technical field of tunnel construction, specifically relating to a method for excavating and constructing tunnel alignment spacing sections. Background Technology

[0002] Due to the limitations of geological conditions and the complexity of mountain structures, tunnel intersections are inevitable during tunnel construction. Because the two tunnels have small or extremely small clearances, there will be many problems during excavation. For example, when two adjacent tunnels with small clearances intersect, the blasting construction of the later tunnel is prone to damage to the structure of the earlier tunnel, which can easily lead to instability and poses a high risk.

[0003] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a method for excavating and constructing tunnel alignment spacing sections.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for excavating and constructing a tunnel with variable alignment spacing includes the following steps: Step S1: The pilot tunnel is advanced using the step method. During the advancement process, the initial support and secondary lining are carried out by excavating and supporting simultaneously until the tunnel reaches the section with variable spacing. Step S2: The subsequent tunnel is excavated using the step method, with the lag length matching the length of the variable line spacing section. Step S3: The pilot tunnel and the rear tunnel are advanced simultaneously. At the junction of the pilot tunnel and the rear tunnel, temporary supports are set up on the side of the initial support of the pilot tunnel closer to the rear tunnel. After the steel arch frame of the pilot tunnel is installed, a support pipe shed is installed from the top of the arch to the top of the rear tunnel and grouting is performed. Step S4: The rear tunnel is advanced by micro-disturbance blasting in the section of the change of track spacing. During the advancement of the rear tunnel, a support pipe roof is installed above the first tunnel at the arch behind the working face, so that the support pipe roofs between the first tunnel and the rear tunnel intersect to form a support curtain. Step S5: The subsequent tunnel merges into the preceding tunnel. A support arch frame corresponding to the outline of the intersection section is set at the intersection section of the preceding tunnel and the subsequent tunnel. The support arch frame is anchored to the surrounding rock outside the intersection section by anchor bolts. After the support arch frame is fixed, the temporary support is removed. The corresponding initial support and secondary lining are set at the intersection section in the form of excavation and support. Step S6: Complete the excavation of the intersection section, and after the first tunnel and the second tunnel have completely intersected, continue the advancement of the second tunnel until the tunnel excavation is completed.

[0006] Preferably, in the area of ​​the variable spacing section, multiple cross braces are provided between the steel arch frames corresponding to the first tunnel or the second tunnel. The cross braces are installed along the tunnel direction on the arch top of the first tunnel or the second tunnel or on the upper edge of the side of the two tunnels that are close to each other. Support holes corresponding to the support pipe shed are provided in the middle of the cross braces.

[0007] Preferably, when the pilot tunnel advances to the junction section, the excavation profile matches the profile of the side of the pilot tunnel corresponding to the junction section; Correspondingly, when the subsequent tunnel advances to the intersection section, the excavation profile matches the profile of the corresponding subsequent tunnel side of the intersection section.

[0008] Preferably, after the rear tunnel is excavated to the junction section and connected to the front tunnel, the rock and soil between the front tunnel and the rear tunnel are excavated in reverse. The spacing of the reverse excavation is not less than the spacing of one support arch, and the two support arches are installed at the same time.

[0009] Preferably, the lead tunnel is provided with a grouting anchor rod extending into the rear tunnel on the side near the change-of-line spacing section. In the same tunnel cross section, the grouting anchor rods are fan-shaped and extend to the centerline of the rear tunnel.

[0010] Preferably, in the section where the distance between the leading tunnel and the following tunnel is less than 20m, anchors are installed between the steel arch frames of the two tunnels. The anchors are installed after the steel arch frame of the following tunnel is installed. On the same tunnel cross section, multiple anchors are evenly distributed from bottom to top along the steel arch frame to the top of the arch.

[0011] Preferably, the micro-disturbance blasting adopts the three-step method for blasting. In any step corresponding to the area, a ring of blast holes is set along its outline, and multiple rows of blast holes are set on the working face of the step. The blast holes corresponding to the arch top and arch bottom in the upper and lower steps are distributed in an arc shape. Multiple auxiliary blast holes are set between the arc-shaped and straight-arranged blast holes to fill the working surface of the corresponding step.

[0012] Preferably, an explosive structure is installed inside the borehole, the explosive structure comprising: A blasting tube, wherein the blasting tube is provided with one or more rows of directional blasting holes; Emulsion explosives, multiple emulsion explosives are distributed inside the blasting tube, the multiple emulsion explosives are tied to the same bamboo strip, the emulsion explosives are equipped with detonators, and the detonators of the multiple emulsion explosives are connected by detonating cords; A support rod, the length of which is adapted to the length of the blasting tube, and a plurality of hinged rods are evenly distributed between the support rod and the blasting tube; In response to pulling the support rod, the hinge rod rotates to support the support rod radially along the blast tube, thereby supporting the blast tube within the borehole.

[0013] Preferably, the blasting tube is made of PVC material, and after the blasting structure is filled, the borehole opening is filled with drilling mud to seal it. Multiple blasting structures on the same step are connected to the corresponding detonation device.

[0014] Beneficial effects: By staggering the construction of the preliminary tunnel and the subsequent tunnel, the tunnels converge after the preliminary tunnel is constructed and initially supported, thereby reducing interference to the section with variable alignment during construction. Furthermore, the interlacing of the supporting pipe roofs forms a supporting curtain, ensuring the stability of the construction. At the convergence point, blasting is carried out using the pressure relief holes of the blasting pipe for directional blasting, reducing blasting disturbance and improving construction safety. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a schematic diagram of the construction of the intersection section in a specific embodiment provided by the present invention; Figure 2 This is a schematic diagram of the borehole distribution in a specific embodiment provided by the present invention; Figure 3 This is a simplified structural diagram of the blasting device in a specific embodiment of the present invention.

[0016] In the diagram: 1. Preliminary tunnel; 2. Subsequent tunnel; 3. Support arch; 4. Temporary support; 5. Horizontal brace; 6. Support pipe shed; 11. Blasting hole; 12. Hinge rod; 13. Support rod; 14. Ratchet; 15. Boiling mud; 16. Blasting pipe; 17. Collar; 18. Blasting hole. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0018] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0020] like Figure 1-3 As shown, a method for excavating a tunnel with a changing alignment spacing section includes the following steps: Step S1, advancing the pilot tunnel 1 using the bench method, with initial support and secondary lining constructed as excavation progresses, until the changing alignment spacing section is reached; Step S2, advancing the subsequent tunnel 2 using the bench method, lagging behind the pilot tunnel 1, with the lag length matching the length of the changing alignment spacing section. This method places excessive restrictions on the specific construction steps of the bench method.

[0021] In this embodiment, when the tunnel 1 and the tunnel 2 are being constructed, a pipe roof is built using a concrete arch as a guide wall. Cement slurry is injected into the pipe roof using a high-pressure pump to solidify the surrounding soil and rock of the tunnel. Specifically, during the arch construction, after surveying and setting out, an excavator is used to excavate the pouring trench corresponding to the arch outline. After re-surveying, the pouring trench is then trimmed by manual excavation. Reinforcing bars are tied in the pouring trench, and positioning rings are welded or tied to the reinforcing bars. A guide pipe passes through the positioning ring and is driven into the external soil and rock of the tunnel at a set angle. The top formwork and end formwork corresponding to the pouring trench are installed. The end formwork has a perforation for the guide pipe, and the perforation is sealed to the guide pipe. After backfilling the soil and rock on both sides of the tunnel, the arch is poured from the top of the pouring trench. After the arch has initially set, the top of the arch is backfilled with soil and rock, and then a slope protection is constructed.

[0022] The first-cycle pipe roof is inserted into the rock and soil outside the tunnel from the guide pipe. The end of the pipe roof inserted into the guide pipe is provided with an external thread corresponding to the guide pipe. It is fixed to the guide pipe through the threaded connection. A grouting valve is provided at the end of the pipe roof. After the pipe roof is numbered, grouting is performed in alternate holes. First, the "odd" holes are grouted and solidified, and then the "even" holes are grouted.

[0023] The bottom of the casting trench and the corresponding external rock and soil of the tunnel are used as the bottom formwork of the arch and the end formwork on one side of the tunnel extension direction, respectively. A steel frame is set at the bottom of the casting trench, and the steel frame is connected to the internal steel reinforcement skeleton of the arch. After the arch concrete reaches the preset strength, the tunnel is excavated. The working face is divided into core soil and outer soil. The outer soil is divided into multiple excavation areas along the extension direction of the arch. Multiple excavation areas are excavated in a symmetrical excavation manner.

[0024] The core soil shape is adapted to the tunnel outline, and the outer soil has a radial width of not less than 1.2m. The outer soil is divided into multiple excavation areas along the extension direction of the arch, and the multiple excavation areas are excavated in a symmetrical excavation manner.

[0025] Specifically, the outer soil can be divided into 8-10 excavation zones. The excavation depth of each excavation zone is matched with the thickness of the arch in the tunnel extension direction. Taking 8 excavation zones as an example, the excavation zones are numbered 1-8 in a clockwise direction, and the excavation sequence is 1, 8, 2, 7, 3, 6, 4, 5.

[0026] The lower edge of the core soil is located at the bottom of the tunnel invert. After the excavation of each excavation area is completed, hydraulic cylinders are directly installed on the arch and the core soil. Prestress is applied by the hydraulic cylinders before the next excavation area is excavated. After the excavation is completed, multiple hydraulic cylinders are depressurized simultaneously. After the depressurization is completed, the core soil is removed in one go, and then the tunnel body is excavated using the bench method.

[0027] Support plates corresponding to each hydraulic cylinder are installed on the core soil. Multiple support plates are spliced ​​to form an arch corresponding to the outer wall of the core soil. After the working face inside the arch is excavated, the tunnel body is excavated. As the tunnel body is excavated, initial support is constructed on the inner wall of the arch. The corresponding initial support inside the arch is constructed in one go. There is no need to distinguish between the initial support of the lower step and the initial support of the upper step. The steel arch frame is fixed to the steel frame by welding. The steel frame can be a double row of I-beams or a truss frame.

[0028] After excavation of each tunneling area is completed, hydraulic cylinders are directly installed on the arch and core soil. Prestress is applied through the hydraulic cylinders before excavation of the next tunneling area. After excavation, multiple hydraulic cylinders are depressurized simultaneously. After depressurization, the tunnel body is excavated using the step method. As the tunnel body is excavated, initial support is constructed on the inner wall of the arch. The steel arch frame of the initial support is fixed to the steel frame by welding.

[0029] In step S3, the preliminary tunnel 1 and the subsequent tunnel 2 are advanced simultaneously. At the intersection of the preliminary tunnel 1 and the subsequent tunnel 2, the initial support of the preliminary tunnel 1 is set up as a temporary support 4 on the side closer to the subsequent tunnel 2. The temporary support 4 is half of the steel arch frame. The corresponding steel arch frame in the preliminary tunnel 1 is temporarily fixed with bolts on the side closer to the subsequent tunnel 2. Generally, at the intersection, the excavation outline of the side of the preliminary tunnel 1 away from the subsequent tunnel 2 is adapted to the outline of the corresponding intersection section. The arch top of the corresponding steel arch frame in the preliminary tunnel 1 is located at the arch top, and the side from the arch top towards the subsequent tunnel 2 is the temporary support 4. The cross brace 5 is located on this temporary support 4. After the construction of the corresponding steel arch frame in the preliminary tunnel 1 is completed, the side from the arch top towards the subsequent tunnel 2 is temporarily fixed. 2. A supporting pipe shed 6 is installed above and grouting is performed. In the area of ​​the variable spacing section, multiple cross braces 5 are provided between the steel arch frames corresponding to the first tunnel 1 or the second tunnel 2. The cross braces 5 can be I-beams, and the two ends are connected to the steel arch frames by welding or bolting. The cross braces 5 are installed along the tunnel direction on the arch top of the first tunnel 1 or the second tunnel 2 and on the upper edge of the side of the two that are close to each other. Generally, no less than three cross braces 5 are set. One of the three cross braces 5 is temporarily located on the arch top of the intersection section (first tunnel 1), and the other two are distributed along the temporary support 4 at intervals in the direction of the arch foot on one side of the second tunnel 2. A support hole corresponding to the supporting pipe shed 6 is provided in the middle of the cross brace 5. The pipe shed is positioned and fixed through the support hole.

[0030] In step S4, the subsequent tunnel 2 is advanced using micro-disturbance blasting in the section with varying spacing. Micro-disturbance blasting can reduce disturbance to the surrounding rock of the tunnel and reduce the probability of instability. During the advancement of the subsequent tunnel 2, support pipe roofs 6 are installed above the preceding tunnel 1 at the arch behind the working face, so that the support pipe roofs 6 between the preceding tunnel 1 and the subsequent tunnel 2 intersect to form a support curtain. The support pipe roofs 6 installed by the subsequent tunnel 2 above the preceding tunnel 1 and the support pipe roofs 6 installed by the preceding tunnel 1 above the subsequent tunnel 2 are staggered in the tunnel extension direction. In this embodiment, grouting holes are provided on the support pipe roofs 6, so as to consolidate through grouting and improve the stability of the surrounding rock of the tunnel.

[0031] Step S5: The subsequent tunnel 2 merges into the preceding tunnel 1. A support arch 3 corresponding to the outline of the intersection section is set at the intersection section of the preceding tunnel 1 and the subsequent tunnel 2. The support arch 3 is adapted to the shape of the intersection section. The support arch 3 is anchored to the surrounding rock outside the intersection section by anchor rods. After the support arch 3 is fixed, the temporary support 4 is removed. In this embodiment, a normal steel arch corresponding to the subsequent tunnel 2 is set before the subsequent tunnel 2 merges with the preceding tunnel. After the subsequent tunnel 2 merges with the preceding tunnel, a support pipe shed 6 is set between the support arch 3. The corresponding cross brace 5 of the support pipe shed 6 fixes the support arch 3.

[0032] At the intersection section, the corresponding initial support and secondary lining are set up in the form of excavation and support.

[0033] Step S6: Complete the excavation of the intersection section, and after the first tunnel 1 and the second tunnel 2 have completely intersected, continue to advance the second tunnel 2 until the tunnel excavation is completed.

[0034] When the first tunnel 1 advances to the junction section, the excavation profile matches the profile of the side of the junction section corresponding to the first tunnel 1. Similarly, when the second tunnel 2 advances to the junction section, the excavation profile matches the profile of the side of the junction section corresponding to the second tunnel 2. This allows the tunnel profile corresponding to the junction section to be directly formed during the construction of the second tunnel.

[0035] To ensure the stability of the initial tunnel, in this application, after the subsequent tunnel 2 is excavated to the junction section and connected to the preceding tunnel 1, the rock and soil between the preceding tunnel 1 and the subsequent tunnel 2 are excavated in reverse. The spacing of the reverse excavation is not less than the spacing of one support arch 3, so as to ensure sufficient construction space, and two support arches 3 are installed (the number of support arches 3 is determined according to the spacing of the reverse excavation, for example, if two arches are excavated in reverse, then three support arches 3 are installed). In this way, the stability of the tunnel during this period is ensured by the two support arches 3 installed at the same time.

[0036] In this embodiment, a grouting anchor rod extending towards the rear tunnel 2 is provided on the side of the pilot tunnel 1 near the change-of-alignment section. On the same tunnel cross section, the grouting anchor rods are fan-shaped and extend to the centerline of the rear tunnel 2. The grouting anchor rods ensure the stability of the side of the pilot tunnel 1 corresponding to the rear tunnel 2, thereby reducing the interference caused by blasting. In the change-of-alignment section where the distance between the pilot tunnel 1 and the rear tunnel 2 is less than 20m, a tie anchor is installed between the steel arch frames of the two tunnels. The tie anchor is installed after the steel arch frame of the rear tunnel 2 is installed. On the same tunnel cross section, multiple tie anchors are evenly distributed from bottom to top along the steel arch frame to the top of the arch, and are fixed by the tie anchors to ensure the stability of the steel arch frame and the stable support of the central core soil.

[0037] In another optional embodiment, the micro-disturbance blasting employs a three-stage method. The specific three-stage construction steps are conventional techniques and will not be elaborated here. In any stage corresponding to a given area, a ring of blast holes 11 is set along its outline. Multiple rows of blast holes 11 are set on the working surface of the stage. The depth of the blast holes 11 is 1–3.3 m, the row spacing is 70 cm, and the spacing between holes E = 70–95 cm. In the upper and lower stages, the blast holes 11 corresponding to the arch crown and arch bottom are distributed in an arc shape. Multiple auxiliary blast holes 11 are set between the arc-shaped and straight-arranged blast holes 11 to fill the working surface of the corresponding stage.

[0038] In this embodiment, a blasting structure is installed inside the borehole 11. The blasting structure includes a blasting tube 16, emulsion explosives, and a support rod 13. The blasting tube 16 has one or more rows of directional blasting holes 18 (also called pressure relief holes). During installation, blasting is carried out in a directional manner using the blasting holes 18 to reduce blasting disturbance. Multiple emulsion explosives are distributed inside the blasting tube 16 and are tied to the same bamboo strip to maintain a preset distance between them. Each emulsion explosive contains a detonator, and the detonators of the multiple emulsion explosives are connected by a detonating cord. The detonators are electronic detonators. The length of the support rod 13 is adapted to the length of the blasting tube 16. After the blasting device is lowered into the borehole 11, the hole is sealed with stemming material 15. Multiple hinge rods 12 are evenly distributed between the support rod 13 and the blasting tube 16. The hinge rods 12 are located on the side of the blasting tube 16 away from the blasting hole 18. One end of the hinge rod 12 is fixed to the blasting tube 16 by a collar 17 corresponding to the blasting tube 16. The collar 17 is sleeved on the blasting tube 16. The other end of the hinge rod 12 is hinged to the hinge rod 12 by a hinge shaft. Anti-slip texture is provided on the side of the blasting tube 16 away from the hinge rod 12. By pulling the support rod 13, the support tube and the blasting tube 16 move away from each other under the action of the hinge rod 12, thus supporting them on opposite sides of the blasting hole 11. This allows the blasting tube 16 to be stably supported in the blasting hole 11, and the blasting hole 18 of the blasting tube 16 to be blasted along the pre-selected direction, improving the blasting accuracy.

[0039] In this embodiment, ratchet teeth 14 are spaced apart on the outer wall of the hinge rod 12 to ensure support stability. Furthermore, the hinge rod 12 and the support rod 13 are made of rubber or PVC, which can generate a certain elasticity through deformation, thereby ensuring the stability of the blasting tube 16 support. The support rod 13 extends out of the blast hole 11 at a certain distance, generally 3-10cm. In this embodiment, the blasting tube 16 is made of PVC. After the blasting structure is filled, the opening of the blast hole 11 is filled with drilling mud 15 for sealing. After the blasting tube 16 is fixed by pulling the support rod 13, the drilling mud 15 is sealed. Multiple blasting structures on the same step are connected to the corresponding detonation devices.

[0040] In another optional embodiment, a support flange is fixed to one end of the blasting tube 16 corresponding to the borehole 11. The support flange is adapted to the diameter of the borehole 11, thus providing high stability within the borehole 11. The support rod 13 passes through the support flange and is threadedly connected to a locking nut. A slotted hole is provided on the support flange. As the locking nut is rotated, the hinge rod 12 rotates to radially support the support rod 13 along the blasting tube 16. In this embodiment, after the blasting device is placed, there is a certain distance between the support flange and the borehole 11, generally 10-15cm. At this time, the locking nut is locked by a sleeve. The sleeve is correspondingly fitted to the hinge rod 12, and the end of the sleeve has a hexagonal tube wall corresponding to the inner wall of the locking nut, so that the locking nut can be rotated when the blasting device is placed. The support flange is made of PVC material, and the inside of the support flange has an assembly hole tangent to the blasting tube 16. The two are fixed by heat fusion or adhesive bonding.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A method for excavating and constructing tunnel sections with variable alignment spacing, characterized in that, Includes the following steps: Step S1: The pilot tunnel is advanced using the step method. During the advancement process, the initial support and secondary lining are carried out by excavating and supporting simultaneously until the tunnel reaches the section with variable spacing. Step S2: The subsequent tunnel is excavated using the step method, with the lag length matching the length of the variable line spacing section. Step S3: The pilot tunnel and the rear tunnel are advanced simultaneously. At the junction of the pilot tunnel and the rear tunnel, temporary supports are set up on the side of the initial support of the pilot tunnel closer to the rear tunnel. After the steel arch frame of the pilot tunnel is installed, a support pipe shed is installed from the top of the arch to the top of the rear tunnel and grouting is performed. Step S4: The rear tunnel is advanced by micro-disturbance blasting in the section of the change of track spacing. During the advancement of the rear tunnel, a support pipe roof is installed above the first tunnel at the arch behind the working face, so that the support pipe roofs between the first tunnel and the rear tunnel intersect to form a support curtain. Step S5: The subsequent tunnel merges into the preceding tunnel. A support arch frame corresponding to the outline of the intersection section is set at the intersection section of the preceding tunnel and the subsequent tunnel. The support arch frame is anchored to the surrounding rock outside the intersection section by anchor bolts. After the support arch frame is fixed, the temporary support is removed. The corresponding initial support and secondary lining are set at the intersection section in the form of excavation and support. Step S6: Complete the excavation of the intersection section, and after the first tunnel and the second tunnel have completely intersected, continue the advancement of the second tunnel until the tunnel excavation is completed.

2. The method for excavating and constructing tunnel alignment spacing sections according to claim 1, characterized in that, In the area of ​​the variable spacing section, multiple cross braces are provided between the steel arch frames corresponding to the first tunnel or the second tunnel. The cross braces are installed along the tunnel direction on the arch top of the first tunnel or the second tunnel or on the upper edge of the side of the two that are close to each other. There are support holes for the corresponding support pipe shed in the middle of the cross braces.

3. The method for excavating and constructing tunnel alignment spacing sections according to claim 1, characterized in that, When the pilot tunnel advances to the junction section, the excavation profile matches the profile of the side of the pilot tunnel corresponding to the junction section. Correspondingly, when the subsequent tunnel advances to the intersection section, the excavation profile matches the profile of the corresponding subsequent tunnel side of the intersection section.

4. The method for excavating and constructing tunnel alignment spacing sections according to claim 3, characterized in that, After the rear tunnel is excavated to the junction section and connected to the front tunnel, the rock and soil between the front tunnel and the rear tunnel are excavated in reverse. The spacing of the reverse excavation is not less than the spacing of one support arch, and two support arches are installed at the same time.

5. The method for excavating and constructing tunnel alignment spacing sections according to claim 1, characterized in that, The pilot tunnel is equipped with grouting anchors that extend into the rear tunnel on the side near the section where the alignment changes. On the same tunnel cross section, the grouting anchors are fan-shaped and extend to the centerline of the rear tunnel.

6. The method for excavating and constructing tunnel alignment spacing sections according to claim 5, characterized in that, In sections where the distance between the lead tunnel and the follow tunnel is less than 20m, anchors are installed between the steel arch frames of the two tunnels. The anchors are installed after the steel arch frame of the follow tunnel is installed. On the same tunnel cross section, multiple anchors are evenly distributed from bottom to top along the steel arch frame to the top of the arch.

7. The method for excavating and constructing tunnel alignment spacing sections according to claim 1, characterized in that, The micro-disturbance blasting adopts the three-step method. In any step corresponding to the area, a ring of blast holes is set along its outline, and multiple rows of blast holes are set on the working face of the step. The blast holes corresponding to the arch top and arch bottom in the upper and lower steps are distributed in an arc shape. Multiple auxiliary blast holes are set between the arc-shaped and straight-arranged blast holes to fill the working surface of the corresponding step.

8. The method for excavating and constructing tunnel alignment spacing sections according to claim 7, characterized in that, An explosive device is installed inside the borehole. The explosive device includes: A blasting tube, wherein the blasting tube is provided with one or more rows of directional blasting holes; Emulsion explosives, multiple emulsion explosives are distributed inside the blasting tube, the multiple emulsion explosives are tied to the same bamboo strip, the emulsion explosives are equipped with detonators, and the detonators of the multiple emulsion explosives are connected by detonating cords; A support rod, the length of which is adapted to the length of the blasting tube, and a plurality of hinged rods are evenly distributed between the support rod and the blasting tube; In response to pulling the support rod, the hinge rod rotates to support the support rod radially along the blast tube, thereby supporting the blast tube within the borehole.

9. The method for excavating and constructing tunnel alignment spacing sections according to claim 8, characterized in that, The blasting tube is made of PVC. After the blasting structure is filled, the borehole opening is sealed with drilling mud. Multiple blasting structures on the same step are connected to the corresponding detonation device.

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