Construction method for excavation of cross section of oblique crossing tunnel

Abstract

The invention discloses a construction method for excavation of a cross section of a skew tunnel. The method comprises the following steps: excavating and supporting an adit according to a design section of an adit cross section until a tunnel face of the adit is parallel to an axis of a main hole, and reserving a first set distance a between the tunnel face of the adit parallel to the axis of the main hole and an excavation section of a standard section of the main hole; the main hole cross section is divided into an excavation tunneling section and a grooving tunneling section according to the upstream and downstream sequence, the branch hole cross section enters the grooving tunneling section to conduct the grooving tunneling process, and the main hole cross section obtained after grooving is adopted to conduct excavation tunneling on the excavation tunneling section in the axis direction of the main hole till the excavation tunneling section penetrates through the large-included-angle side intersection point A of the branch hole and the main hole; and tunneling and supporting the upstream and downstream working faces of the standard section of the main tunnel respectively. According to the method, the requirement for vehicle passing from the branch hole to the small-included-angle side main hole is met, the same excavation section is adopted for construction of the main hole intersection section, and the working efficiency of site construction is improved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a construction method for excavating an intersection section of an oblique tunnel. Background Art

[0002] The excavation of the intersection section of the oblique tunnel is a challenging engineering task due to its large span and difficult construction.

[0003] However, the excavation method in the prior art has the following problems:

[0004] First, due to the complex geological conditions and other factors, it is difficult to set the intersection angle of the tunnel to be orthogonal. However, if the oblique intersection is excavated in the normal way, there are often problems such as over-excavation on the small angle side of the intersection section that is difficult to retain.

[0005] Second, after entering the main tunnel from the branch tunnel, since the intersection section is a key part, steel arch frames are often used for reinforced support, and the elevations of the top plates of the main tunnel and branch tunnels are often inconsistent, resulting in frequent changes in cross-section during blasting excavation, which will cause a certain amount of over-excavation. At the same time, if poor surrounding rock is encountered, the construction safety risk will increase. In addition, the specifications and sizes of the steel arch frames in the intersection section are different due to the different heights of the tunnel sections, which will reduce construction efficiency and increase engineering safety risks. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a construction method for excavating the intersection section of an oblique tunnel, which can not only regularize the side excavation of the small angle of the intersection section, but also enable the intersection section of the main tunnel to be constructed with the same excavation section, unify the steel arch structure dimensions required for support, make the initial support of the intersection section easy to construct, and improve the work efficiency of on-site construction.

[0007] In order to achieve the above-mentioned object, the present invention is designed to excavate the intersection section of an oblique tunnel, which is characterized in that it includes the following steps:

[0008] S1) After reaching the construction pile number of the branch tunnel intersection section, the branch tunnel is excavated and supported according to the design section of the branch tunnel intersection section until the branch tunnel face is parallel to the main tunnel axis, and a first set distance a is retained between the branch tunnel face parallel to the main tunnel axis and the excavation section of the main tunnel standard section;

[0009] S2) dividing the main tunnel intersection section into an excavation excavation section and a groove excavation section in an upstream and downstream order, with the groove excavation section close to the small angle side of the main tunnel and the excavation excavation section close to the large angle side of the main tunnel;

[0010] Enter the groove excavation section from the branch tunnel intersection section and carry out the groove excavation process, and the groove width meets the normal operation requirements of the initial support construction trolley;

[0011] After the groove excavation section is completed, the main tunnel cross section obtained by the groove is used to open the excavation section and excavate along the axis of the main tunnel until it passes through the intersection point A on the side with the large angle between the branch tunnel and the main tunnel;

[0012] For the groove excavation section and the excavation excavation section, the main tunnel intersection section steel arch construction shall be carried out immediately after each set excavation distance;

[0013] S3) After the process of step S2) is completed, the excavation and support processes are carried out on the upstream working face of the main tunnel standard section on the large angle side of the main tunnel and the downstream working face of the main tunnel standard section on the small angle side of the main tunnel respectively, and the upstream and downstream working faces of the main tunnel standard section shrink the main tunnel cross section to the main tunnel standard section respectively.

[0014] Furthermore, in S1), a set distance a is retained between the branch tunnel face parallel to the main tunnel axis and the main tunnel standard section excavation section to meet the requirement of vehicle passing at a small angle.

[0015] Furthermore, in S1), when constructing the steel arch support of the branch tunnel, in order to avoid construction difficulties at the small angle side of the main tunnel where the circle changes to the square, multiple branch tunnel advance anchors are installed in advance on the small angle side of the main tunnel of the third steel arch frame of the branch tunnel, and the external insertion angle of the branch tunnel advance anchor is higher than the intersection section of the main tunnel.

[0016] Furthermore, in S1), the branch tunnel steel arch frame support of the branch tunnel intersection section adopts a gradual arrangement pattern, from the first steel arch frame 1 of the branch tunnel to the last steel arch frame 3 of the branch tunnel, it gradually changes from being perpendicular to the branch tunnel axis to being parallel to the main tunnel axis.

[0017] Furthermore, in S1), when constructing the steel arch support of the branch tunnel, the spacing between adjacent steel arches on the small angle side of the main tunnel and the spacing between adjacent steel arches on the large angle side of the main tunnel are arranged according to the size of the angle.

[0018] Further, in S2), the groove excavation section II is divided into a first groove excavation section II1 and a second groove excavation section II2 in accordance with the groove excavation order, the first groove excavation section II1 adopts an upward top-lifting process, and the second groove excavation section II2 adopts a downward groove excavation process; the excavation excavation section III includes a first excavation excavation section III1 and a second excavation excavation section III2, and the first excavation excavation section III1 is adjacent to the first groove excavation section II1, and the second excavation excavation section III2 is adjacent to the second groove excavation section II2.

[0019] Furthermore, in S2), the main tunnel intersection section steel arch frame includes a plurality of main tunnel steel arch frames 5 arranged at intervals, each of the main tunnel steel arch frames 5 has a main tunnel vertical steel frame 6 extending downward near the side of the branch tunnel, and the main tunnel vertical steel frame 6 is connected to the last steel arch frame 3 of the branch tunnel by welding.

[0020] Furthermore, in S2), an advance anchor rod 7 is installed within 120° of the top arch of the steel arch frame of the main tunnel intersection section to prepare for the contraction section in step S3.

[0021] Furthermore, in S3), the downstream working face of the standard section of the main tunnel includes a guide tunnel section IV1 located in the middle of the working face and excavation sections IV2 located on both sides of the working face. When excavating the downstream working face of the standard section of the main tunnel on the small angle side of the main tunnel, the guide tunnel section IV1 is excavated first, and then the excavation sections IV2 on both sides are excavated, and full-section excavation is adopted after excavating to a safe distance.

[0022] Furthermore, in S3), before excavating the upstream and downstream working faces of the standard section of the main tunnel, double rows of locking anchor rods 8 are installed on the working faces beyond the standard section range of the main tunnel, and the double rows of locking anchor rods 8 are spaced 0.8 to 1.5 m apart, with an external insertion angle of 15° to 45°, and are arranged in a plum blossom shape.

[0023] The advantages of the present invention are:

[0024] 1. The present invention reserves a first set distance a between the branch tunnel face parallel to the main tunnel axis and the excavation section of the standard section of the main tunnel, the purpose of which is to expand the cross-section width of the main tunnel. The expansion of the cross-section width of the main tunnel not only avoids the problem of irregular excavation on the small angle side, but also meets the turning requirements of vehicles on the small angle side. At the same time, the unified excavation section in this way avoids frequent changes in the excavation section during the blasting excavation of the cross section, and uses fewer steel arch frame processing types to facilitate construction, greatly improving construction efficiency;

[0025] 2. The present invention welds the vertical steel frame of the main tunnel near the side of the branch tunnel to the last steel arch frame of the branch tunnel, the purpose of which is to strengthen the arch support of the tunnel intersection section, ensure the stability of the tunnel rock column of the oblique tunnel intersection section, and improve the construction quality and engineering safety;

[0026] 3. Before excavating the upstream and downstream working faces of the main tunnel standard section, the present invention applies double-row locking anchor rods on the working faces beyond the standard section range of the main tunnel, the purpose of which is to strengthen the end wall locking and improve construction safety;

[0027] The invention is used for the construction method of excavating the intersection section of the oblique tunnel. The method adopts the mode of expanding the intersection section width of the main tunnel, strengthening the arch support of the intersection section of the tunnel, and strengthening the end wall lock. It not only meets the demand of passing vehicles from the branch tunnel to the main tunnel on the small angle side, but also enables the intersection section of the main tunnel to be constructed with the same excavation section, unifies the steel arch structure size required for the support, makes the initial support of the intersection section easy to construct, and improves the work efficiency, construction quality and engineering safety of the on-site construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a construction process diagram of the intersection section of the oblique tunnel in the present invention;

[0029] Figure 2 It is the support axonometric diagram of the intersection section of the oblique tunnel in the present invention;

[0030] In the figure: branch tunnel intersection section Ⅰ, groove excavation section Ⅱ, excavation excavation section Ⅲ, pilot tunnel sections IV1 and IV2;

[0031] Grooving excavation section II includes: first groove excavation section II1, second groove excavation section II2;

[0032] The excavation section III includes: the first excavation section III1 and the second excavation section III2;

[0033] The first steel arch frame of the branch tunnel 1, the third steel arch frame of the branch tunnel 2, the last steel arch frame of the branch tunnel 3, the advance anchor rod 4 of the branch tunnel, the steel arch frame of the main tunnel 5, the vertical steel frame of the main tunnel 6, the advance anchor rod 7, and the double-row locking anchor rod 8;

[0034] First, set the distance a and the intersection point A of the branch tunnel and the main tunnel at the largest angle. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0037] The present invention provides a construction method for excavating an intersection section of an oblique tunnel, comprising the following steps:

[0038] S1) Branch tunnel construction: After reaching the construction pile number of branch tunnel intersection section I, the branch tunnel is excavated and supported according to the designed section of branch tunnel intersection section I until the branch tunnel face is parallel to the main tunnel axis, and the first set distance a is retained between the branch tunnel face parallel to the main tunnel axis and the excavation section of the standard section of the main tunnel.

[0039] Specifically, a set distance a is retained between the branch tunnel face parallel to the main tunnel axis and the excavation section of the standard section of the main tunnel to meet the needs of vehicles passing on the side with a small angle.

[0040] The present invention retains a first set distance a between the branch tunnel face parallel to the main tunnel axis and the excavation section of the standard section of the main tunnel, with the purpose of expanding the width of the main tunnel intersection section. The expansion of the main tunnel intersection section width not only meets the turning requirements of vehicles on the small angle side, but also avoids frequent changes in the excavation section during the blasting excavation of the intersection section, thereby greatly improving the construction efficiency.

[0041] The steel arch support of the branch tunnel in the branch tunnel intersection section adopts a gradual arrangement pattern, from the first steel arch 1 of the branch tunnel to the last steel arch 3 of the branch tunnel, it gradually changes from being perpendicular to the branch tunnel axis to being parallel to the main tunnel axis.

[0042] In this embodiment, all the steel arch frames from the first steel arch frame 1 of the branch tunnel to the last steel arch frame 3 of the branch tunnel are I20a steel arch frames.

[0043] Specifically, when constructing the steel arch support of the branch tunnel, the spacing of the adjacent steel arches on the small angle side of the main tunnel and the spacing of the adjacent steel arches on the large angle side of the main tunnel are arranged according to the angle size. For example, the spacing of the adjacent steel arches on the small angle side of the main tunnel is 0.8-1.2m, and the spacing of the adjacent steel arches on the large angle side of the main tunnel is 2.5-3.5m. In this embodiment, the spacing of the adjacent steel arches on the small angle side of the main tunnel is 1.0m, and the spacing of the adjacent steel arches on the large angle side of the main tunnel is 3.0m.

[0044] In addition, when constructing the steel arch support of the branch tunnel, in order to avoid construction difficulties at the small angle of the main tunnel and the subsequent top-cutting groove construction, the branch tunnel advance anchor 4 should be installed in advance when the section is constructed in front of the predetermined heading and at a certain distance. The external insertion angle of the branch tunnel advance anchor 4 should be determined by the height difference and distance between it and the highest point of the main tunnel construction.

[0045] In this embodiment, 12 branch hole advance anchor rods 4 are installed in advance on the small angle side of the main hole of the third steel arch frame 2 of the branch hole, and the external insertion angle of the branch hole advance anchor rod 4 is higher than the main hole intersection range. L=6.0m.

[0046] S2) includes the construction of the branch tunnel along the vertical direction of the main tunnel and the intersection section of the main tunnel.

[0047] The main tunnel intersection section is divided into excavation section III and groove excavation section II in the order of upstream and downstream, and the groove excavation section II is close to the small angle side of the main tunnel, and the excavation section III is close to the large angle side of the main tunnel;

[0048] Enter the groove excavation section II from the branch tunnel intersection section I, and carry out the groove excavation process, and the groove width meets the normal operation requirements of the initial support construction trolley.

[0049] Specifically, after reaching the construction face described in step S1), a groove should be cut toward the main hole along the direction perpendicular to the main hole on the side with a small angle, and the width of the groove should meet the requirements of the initial support trolley construction operation. The groove cutting process should be supported by I20a steel arch frame with a spacing of 1.0m. After each section of steel arch frame construction conditions are reached, the steel arch frame should be installed and fixed with locking anchor rods. After the connection is reliable, the next stage of groove cutting construction should be carried out, and this cycle will be repeated until the groove cutting is completed. The locking anchor rod adopts L = 4.5m locking anchor rod.

[0050] The excavation advance in each cycle of the grooving process should not exceed 2m. If the surrounding rock conditions are poor, it can be divided into upper and lower steps for excavation.

[0051] Specifically, the groove excavation section II is divided into a first groove excavation section II1 and a second groove excavation section II2 in accordance with the groove excavation order. The first groove excavation section II1 adopts an upward top-lifting process, and the second groove excavation section II2 adopts a downward groove excavation process. The excavation excavation section III includes a first excavation excavation section III1 and a second excavation excavation section III2, and the first excavation excavation section III1 is adjacent to the first groove excavation section II1, and the second excavation excavation section III2 is adjacent to the second groove excavation section II2.

[0052] For the groove excavation section II and the excavation excavation section III, the steel arch frame of the main tunnel intersection section will be constructed immediately after each set distance of excavation.

[0053] Specifically, the main tunnel intersection section steel arch frame includes a plurality of main tunnel steel arch frames 5 arranged at intervals, each of which has a main tunnel vertical steel frame 6 extending downward near the side of the branch tunnel, and the main tunnel vertical steel frame 6 is connected to the last steel arch frame 3 of the branch tunnel by welding. At the same time, the adjacent main tunnel vertical steel frames 6 are connected by The steel bars are welded together. If the surrounding rock is poor, half-section I20a I-beams should be used for welding connection.

[0054] After the branch tunnel is grooved toward the main tunnel, the main tunnel vertical steel frame 6 is used to connect the main tunnel steel arch frame 5 with the branch tunnel steel arch frame, which can ensure that the excavation section is consistent during the main tunnel construction process and improve the construction efficiency.

[0055] In this embodiment, the main tunnel steel arch frame 5 and the main tunnel vertical steel frame 6 are both I20a steel frames.

[0056] After the groove excavation section II is completed, the main tunnel cross section obtained by the groove is used to open the excavation section III along the main tunnel axis until it passes through the intersection point A of the branch tunnel and the main tunnel side with a large angle. In other words, the branch tunnel and the main tunnel side with a large angle will form a certain distance end wall. In this embodiment, two I20a main tunnel vertical steel frames 6 are constructed within this distance to connect with the I20a main tunnel steel arch frame 5.

[0057] Preferably, the main tunnel intersection section steel arch frame has an advanced anchor rod 7 within 120° of the top arch to prepare for the shrinkage section in step S3. The advanced anchor rod 7 of L=4.5m is used to prepare for the shrinkage section in the subsequent construction process.

[0058] S3) Excavation of upstream and downstream working faces of the main tunnel standard section: After the step S2) process is completed, the excavation and support processes are carried out on the upstream working face of the main tunnel standard section on the large angle side of the main tunnel and the downstream working face of the main tunnel standard section on the small angle side of the main tunnel respectively, and the upstream and downstream working faces of the main tunnel standard section shrink the main tunnel cross section to the main tunnel standard section respectively.

[0059] The upstream working face of the standard section of the main tunnel on the large-angle side of the main tunnel is excavated and supported according to the designed section. For the excavation of the downstream working face of the standard section of the main tunnel on the small-angle side, in order to avoid damage to the rock pillar on the small-angle side during the blasting process, the following excavation method can be adopted: first, a pilot tunnel can be excavated for a certain distance and then the outline of the main tunnel can be grooved in the direction perpendicular to the axis of the main tunnel, and then normal excavation can be carried out.

[0060] Specifically, the downstream working face of the standard section of the main tunnel is divided into a pilot tunnel section IV1 located in the middle of the working face and excavation sections IV2 located on both sides of the working face. The excavation is carried out by first excavating the pilot tunnel section IV1 and then the excavation sections IV2 on both sides. After excavating to a safe distance, full-section excavation is adopted.

[0061] Preferably, before excavating the upstream and downstream working faces of the main tunnel standard section, double-row locking anchor rods 8 are installed on the working face beyond the standard section of the main tunnel, and the external insertion angle of the double-row locking anchor rods 8 should be determined according to the angle between the branch tunnel and the main tunnel. The double-row locking anchor rods 8 in this embodiment are spaced 0.8 to 1.5 m apart, with an external insertion angle of 15° to 45°, and are arranged in a plum blossom shape.

[0062] The end wall at the main tunnel where the cross-section changes (the side with a small angle between the branch tunnel and the main tunnel) is reinforced by a double row of locking anchor rods 8, and a guide tunnel is used for excavation, which effectively avoids the destruction of the rock column on the small angle side, ensures construction safety and has a certain degree of economy.

[0063] The invention is used for the construction method of excavating the intersection section of the oblique tunnel. The method adopts the mode of expanding the intersection section width of the main tunnel, strengthening the arch support of the intersection section of the tunnel, and strengthening the end wall lock. It not only meets the demand of passing vehicles from the branch tunnel to the main tunnel on the small angle side, but also enables the intersection section of the main tunnel to be constructed with the same excavation section, unifies the steel arch structure size required for the support, makes the initial support of the intersection section easy to construct, and improves the work efficiency, construction quality and engineering safety of the on-site construction.

[0064] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A construction method for excavating an intersection section of an oblique tunnel, characterized in that: The steps include: S1) After reaching the construction pile number of the branch tunnel intersection section (I), the branch tunnel is excavated and supported according to the design section of the branch tunnel intersection section (I) until the branch tunnel face is parallel to the main tunnel axis, and the first set distance (a) is retained between the branch tunnel face parallel to the main tunnel axis and the excavation section of the main tunnel standard section; S2) The main tunnel intersection section is divided into an excavation excavation section (III) and a groove excavation section (II) in the order of upstream and downstream, and the groove excavation section (II) is close to the small angle side of the main tunnel, and the excavation excavation section (III) is close to the large angle side of the main tunnel; Enter the groove excavation section (II) from the branch tunnel intersection section (I) and carry out the groove excavation process, and the groove width meets the normal operation requirements of the initial support construction trolley; After the groove excavation section (II) is completed, the main tunnel cross section obtained by the groove is used to open the excavation section (III) along the axis of the main tunnel until it passes through the intersection point (A) on the side with the large angle between the branch tunnel and the main tunnel; For the groove excavation section (II) and the excavation excavation section (III), the main tunnel intersection section steel arch construction shall be carried out immediately after each excavation of the set distance; S3) After the process of step S2) is completed, the excavation and support processes are carried out on the upstream working face of the main tunnel standard section on the large angle side of the main tunnel and the downstream working face of the main tunnel standard section on the small angle side of the main tunnel respectively, and the upstream and downstream working faces of the main tunnel standard section shrink the main tunnel cross section to the main tunnel standard section respectively.

2. The construction method for excavating the intersection section of an oblique tunnel according to claim 1 is characterized in that: In S1), the set distance (a) between the branch tunnel face parallel to the main tunnel axis and the main tunnel standard section excavation section must meet the small angle side vehicle passing requirements.

3. The construction method for excavating the intersection section of an oblique tunnel according to claim 2 is characterized in that: In S1), when constructing the branch tunnel steel arch support, in order to avoid construction difficulties at the small angle side of the main tunnel where the circle changes to the square, multiple branch tunnel advance anchor rods (4) are installed in advance on the small angle side of the main tunnel of the third steel arch frame (2), and the external insertion angle of the branch tunnel advance anchor rods (4) is higher than the main tunnel intersection range.

4. The construction method for excavating the intersection section of an oblique tunnel according to claim 3 is characterized in that: In S1), the branch tunnel steel arch support at the branch tunnel intersection section adopts a gradual arrangement pattern, from the first steel arch frame (1) of the branch tunnel to the last steel arch frame (3) of the branch tunnel, it gradually changes from being perpendicular to the branch tunnel axis to being parallel to the main tunnel axis.

5. The construction method for excavating the intersection section of an oblique tunnel according to claim 4 is characterized in that: In S1), when constructing the steel arch support of the branch tunnel, the spacing between adjacent steel arches on the small angle side of the main tunnel and the spacing between adjacent steel arches on the large angle side of the main tunnel are arranged according to the size of the angle.

6. The construction method for excavating the intersection section of an oblique tunnel according to claim 1 is characterized in that: S2), the groove excavation section (II) is divided into a first groove excavation section (II1) and a second groove excavation section (II2) in accordance with the groove excavation sequence, the first groove excavation section (II1) adopts an upward top-lifting process, and the second groove excavation section (II2) adopts a downward groove excavation process; the excavation excavation section (III) includes a first excavation excavation section (III1) and a second excavation excavation section (III2), and the first excavation excavation section (III1) is adjacent to the first groove excavation section (II1), and the second excavation excavation section (III2) is adjacent to the second groove excavation section (II2).

7. The construction method for excavating the intersection section of an oblique tunnel according to claim 6 is characterized in that: S2), the main tunnel intersection section steel arch frame includes a plurality of main tunnel steel arch frames (5) arranged at intervals, each of the main tunnel steel arch frames (5) has a main tunnel vertical steel frame (6) extending downward near the side of the branch tunnel, and the main tunnel vertical steel frame (6) is connected to the last steel arch frame (3) of the branch tunnel by welding.

8. The construction method for excavating the intersection section of an oblique tunnel according to claim 7 is characterized in that: In step S2), an advance anchor rod (7) is installed within 120° of the top arch of the steel arch frame of the main tunnel intersection section to prepare for the contraction section in step S3).

9. The construction method for excavating the intersection section of an oblique tunnel according to claim 1, characterized in that: S3), the downstream working face of the standard section of the main tunnel includes a pilot tunnel section (IV1) located in the middle of the working face and excavation sections (IV2) located on both sides of the working face. When excavating the downstream working face of the standard section of the main tunnel on the small angle side of the main tunnel, the pilot tunnel section (IV1) is excavated first, and then the excavation sections (IV2) on both sides are excavated. After excavating to a safe distance, full-section excavation is adopted.

10. The construction method for excavating the intersection section of an oblique tunnel according to claim 9, characterized in that: In S3), before excavating the upstream and downstream working faces of the main tunnel standard section, double rows of locking anchor rods (8) are installed on the working faces beyond the main tunnel standard section range, and the double rows of locking anchor rods (8) are arranged in a plum blossom shape with a spacing of 0.8 to 1.5 m and an external insertion angle of 15° to 45°.

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