A method for oblique top selection of tunnels with uniform cross-section

Abstract

The present invention relates to the field of building construction, and specifically to a method for obliquely crossing and top-lifting a tunnel of equal cross-section. Special-shaped arch frames are used at the intersection of equal-section tunnels, and each special-shaped arch frame has a different structural form according to the different angles of intersection with the line. At the same time, the structural stability of the oblique intersection position is ensured by the arrangement of diagonal braces and portal frames. As a top-lifting support structure for oblique equal-section tunnels, the present invention effectively solves the problem of initial support construction at the oblique intersection position of equal-section tunnels, improves construction quality, and reduces construction safety risks.

Description

Technical Field

[0001] The invention relates to the field of building construction, and in particular to a method for obliquely picking the top of a tunnel with a uniform cross section. Background Art

[0002] During the construction of railway tunnels, there are often times when tunnels of the same cross-section intersect obliquely. Due to the same cross-section, the force structure at the oblique intersection is complex, and deformation and collapse are often prone to occur, which cannot meet the needs of on-site construction. There are major hidden dangers to construction safety and quality during construction, which can easily cause serious economic losses and also bury hidden dangers for subsequent railway operation and traffic safety. The existing construction method is often to first complete the excavation and support according to the contour of the original designed equal-section tunnel, and then expand the excavation at the intersection of the two equal-section tunnels to complete the structural conversion. This method requires the destruction of the steel support at the arch position. However, the force at the arch position is concentrated. Once the steel support at the arch position is damaged, it is very easy for the structure to become unstable and the tunnel to collapse. Summary of the invention

[0003] In order to solve the above-mentioned construction problem of oblique positions of equal-section tunnels, the present invention provides a method for oblique topping of equal-section tunnels, and proposes an idea of ​​an oblique topping support structure system for equal-section tunnels. The structural stability of the oblique positions is enhanced by arranging special-shaped arch frames, diagonal braces and portal frames, which can effectively reduce the safety risks of tunnel topping construction.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a method for oblique top selection of a tunnel with a uniform cross section is proposed, comprising the following steps:

[0005] Step 1: Before excavating the oblique intersection section of two equal-section tunnels, advance measures are set for the surrounding rock within the upper step range of equal-section tunnel I and grouting reinforcement is carried out, and advance support is set above the surrounding rock;

[0006] Step 2, after the advanced support construction is completed, tunnel excavation is carried out, and after the upper step is excavated, initial concrete spraying is carried out to complete the initial support of the upper step, including: upper step arch foot steel support, upper step arch waist steel support, upper step arch top steel support and upper step temporary vertical support steel support four units;

[0007] Step 3: After completing the initial support of two arch frames for the upper steps, suspend the work and start the diagonal brace reinforcement construction to enhance the load bearing capacity of the right-angled part of the initial support of the upper steps;

[0008] Step 4: After the initial support of 6 arches is completed for the upper step construction, the lower step construction is started and the corresponding initial support construction is completed, including: the lower step arch foot steel support and the lower step temporary vertical support steel support, and then the upper and lower steps are promoted synchronously;

[0009] Step 5: After the initial support of the lower step is completed with three arch frames, the inverted arch is excavated. The inverted arch is set only in the oblique position section, and the single excavation is not greater than the threshold. The steel arch frame is used to close the ring;

[0010] Step 6: After the initial support of the oblique intersection section is completed, the upper and lower steps are constructed synchronously according to the normal section for 10m and then the work is suspended to ensure that the lower step is 10m away from the oblique intersection;

[0011] Step 7, construct a portal frame at an oblique position, the portal frame is composed of vertical beams and horizontal beams, both of which are composed of I-beams, the horizontal beam is composed of 3 units, the vertical beam is composed of 2 units, the vertical beam and the horizontal beam are connected by bolts, and the oblique braces of the equal-section tunnel I need to be removed during the construction of the portal frame;

[0012] Step 8: After the portal frame is constructed, an arc-shaped arch frame is constructed inside the portal frame, and an oblique I-beam is arranged on the upper part of the arc-shaped arch frame to be connected with the portal frame by welding;

[0013] Step 9: After the arc-shaped arch frame completes the support, the excavation of the equal-section tunnel II at the oblique position begins. Due to the unequal distances between the left and right sides of the adjustment section, the arch frame spacing is set with non-equidistant settings until the adjustment is completed. Before excavation, the temporary vertical support steel supports of the upper step and the temporary vertical support steel supports of the lower step of the initial support of the equal-section tunnel I within the gantry range need to be removed;

[0014] Step 10: Strengthen monitoring and measurement during the construction process to ensure that the cumulative deformation of the initial support is not greater than the threshold, and the deformation rate after the ring is closed is not greater than the threshold, that is, to carry out waterproof structure construction and follow up the subsequent lining construction in a timely manner.

[0015] The initial support includes: steel arch frame, longitudinal connecting steel bars, locking anchor pipes, system anchor rods, steel mesh and shotcrete.

[0016] In step 2, tunnel excavation is carried out by mechanical milling.

[0017] In step 4, the left and right sides of the lower step should be excavated in staggered steps, with the staggered distance being 2 arch frames.

[0018] In step 5, the single excavation distance threshold of the invert is 3m.

[0019] In step 7, the door frame adopts double-jointed I-beams.

[0020] In step 9, the initial support arch of the uniform-section tunnel I within the gantry range is the vertical unit part of the special-shaped arch, namely, the temporary vertical support steel support of the upper step and the temporary vertical support steel support of the lower step.

[0021] In step 9, the initial support of the adjustment section is adjusted, the short side arch spacing is 0.5m, and the long side arch spacing is 1m.

[0022] The present invention has the following beneficial effects: for the construction of oblique positions of tunnels with the same cross-section, the problem of structural stability is solved by adopting measures such as mechanical milling excavation, special-shaped arch support, temporary reinforcement of diagonal braces, reinforcement of double-jointed I20 I-steel portal frames, and reinforcement of curved arch frames. According to monitoring and measurement results, the cumulative maximum deformation settlement value is 2.4 cm, and the cumulative maximum deformation convergence value is 1.9 cm, which ensures structural safety and reduces construction safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the process of the method for oblique top selection of tunnels with uniform cross-sections according to the present invention.

[0025] Figure 2 It is a schematic diagram of the oblique plane of the uniform cross-section tunnel of the present invention;

[0026] Figure 3 It is a cross-sectional schematic diagram of a uniform cross-section tunnel I of the present invention;

[0027] Figure 4 This is a cross-sectional schematic diagram of a uniform cross-section tunnel II of the present invention;

[0028] In the figure: 1-advance support, 2A-upper step arch foot steel support, 2B-upper step arch waist steel support, 2C-upper step arch top steel support, 2D-upper step temporary vertical support steel support, 3-upper step, 4-lower step, 5A-lower step arch foot steel support, 5B-lower step temporary vertical support steel support, 6-inverted arch, 7-locking foot anchor pipe, 8-cross beam, 9-diagonal brace, 10-vertical beam; 11-arc arch frame. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention. Example 1

[0031] like Figure 1 FIG. 1 is a process flow chart of a method for obliquely picking the top of a medium-section tunnel in an embodiment, comprising:

[0032] Step 1: before excavating the oblique intersection section of two equal-section tunnels, advance measures are set for the surrounding rock within the range of the upper step 3 of the equal-section tunnel I and grouting reinforcement treatment is carried out, and an advance support 1 is set above the surrounding rock;

[0033] Step 2, after the construction of the advanced support 1 is completed, tunnel excavation is carried out, and after the upper step 3 is excavated, initial concrete spraying is carried out to complete the initial support of the upper step, including: upper step arch foot steel support 2A, upper step arch waist steel support 2B, upper step arch top steel support 2C and upper step temporary vertical support steel support 2D four units;

[0034] Step 3, after completing the initial support of the upper step 3 with two arch frames, suspend the operation and start the reinforcement construction of the diagonal brace 9 to enhance the load bearing capacity of the right-angled part of the initial support of the upper step 3;

[0035] Step 4: After the initial support of the upper step 3 is completed for the distance of 6 arch frames, the lower step 4 is started and the corresponding initial support construction is completed, including: two units of the lower step arch foot steel support 5A and the lower step temporary vertical support steel support 5B, and then the upper and lower steps are promoted synchronously;

[0036] Step 5: After the initial support of the lower step 4 is completed with three arch frames, the inverted arch 6 is excavated. The inverted arch 6 is set only in the oblique position section, and the single excavation is not greater than the threshold, and the steel arch frame is used to close the ring;

[0037] Step 6: After the initial support of the oblique intersection section is completed, the upper step 3 and the lower step 4 are synchronously constructed according to the normal section for 10m and then suspended to ensure that the lower step is 10m away from the oblique intersection;

[0038] Step 7, construct a portal frame at an oblique position, the portal frame is composed of a vertical beam 10 and a horizontal beam 8, both of which are made of I-beams, the horizontal beam 8 is composed of 3 units, and the vertical beam 10 is composed of 2 units. The vertical beam 10 and the horizontal beam 8 are connected by bolts. When constructing the portal frame, the diagonal brace 9 of the equal-section tunnel I needs to be removed;

[0039] Step 8, after the construction of the portal frame is completed, the arc-shaped arch frame 11 in the portal frame is constructed, and an oblique I-beam is arranged on the upper part of the arc-shaped arch frame to be connected with the portal frame, and the connection method is welding;

[0040] Step 9, after the arc-shaped arch frame 11 completes the support, the excavation of the equal-section tunnel II at the oblique position begins. Due to the unequal distances between the left and right sides of the adjustment section, the arch frame spacing is set with a non-equidistant setting until the adjustment is completed. Before excavation, the upper step temporary vertical support steel support 2D and the lower step temporary vertical support steel support 5B of the initial support of the equal-section tunnel I within the gantry range need to be removed;

[0041] Step 10: Strengthen monitoring and measurement during the construction process to ensure that the cumulative deformation of the initial support is not greater than the threshold, and the deformation rate after the ring is closed is not greater than the threshold, that is, to carry out waterproof structure construction and follow up the subsequent lining construction in a timely manner.

[0042] The initial support includes: steel arch frame, longitudinal connecting steel bars, locking anchor pipes, system anchor rods, steel mesh and shotcrete.

[0043] The door frame adopts double-jointed I-beams, that is, the flange plates are welded into a whole by using the same I-beams.

[0044] The initial support arch frame of the equal-section tunnel I within the range of the gantry is removed, that is, the upper step temporary vertical support steel support 2D and the lower step temporary vertical support steel support 5B of the initial support of the equal-section tunnel I.

[0045] The arch frames of the equal-section tunnel II are arranged at non-equidistant distances, that is, the arch frame spacing on the short side of the adjustment section is 0.5m, and the arch frame spacing on the long side is 1m.

[0046] Aiming at the construction of oblique positions of tunnels with the same cross-section, the present invention solves the problem of structural stability by adopting measures such as mechanical milling excavation, special-shaped arch support, temporary reinforcement of diagonal braces, reinforcement of double-jointed I20 I-steel portal frames, and reinforcement of curved arch frames. According to the monitoring and measurement results, the structural safety is guaranteed and the construction safety risk is reduced.

[0047] The following describes the application scenario of the present invention. Figure 2 This is a schematic diagram of the oblique plane of a tunnel with a uniform cross section according to the present invention. Figure 3 This is a cross-sectional schematic diagram of a uniform cross-section tunnel I of the present invention, Figure 4 This is a cross-sectional schematic diagram of a uniform cross-section tunnel II of the present invention, and the specific steps are as follows:

[0048] Step 1: Before excavating the oblique intersection of two equal-section tunnels, a φ60mm advanced middle pipe shed is set within the range of step 3 on the upper step of the equal-section tunnel I, with each 9m pipe shed having a lap length of 3m, a circumferential spacing of 50cm, and an external insertion angle of the pipe shed controlled at 1° to 3°. After the construction is completed, drilling is performed to verify the grouting effect before excavation;

[0049] Step 2: Excavation is carried out by using the two-step reserved core soil plus milling excavation method. The excavation distance of each cycle is not more than the distance of 2 arch frames. After the excavation of the upper step 3 is completed, 5 cm thick shotcrete is used to complete the closure in time. The upper step is reinforced with I18 steel arch frames with a spacing of 0.8m, including: upper step arch foot steel support 2A, upper step arch waist steel support 2B, upper step arch top steel support 2C and upper step temporary vertical support steel support 2D. The units are connected by M27 high-strength bolts, and the arch frames are strengthened with φ22mm threaded steel bars. At the same time, the construction of the locking foot anchor pipe is strengthened and grouting is reinforced. The locking foot is a φ42mm steel flower pipe with a length of 4m / root;

[0050] Step 3, after completing the initial support of two arch frames of the upper step 3, suspend the operation and start the diagonal brace reinforcement construction. The diagonal brace is an I18 steel arch frame to enhance the load bearing capacity of the right-angle part of the initial support of the upper step 3;

[0051] Step 4: After the initial support of the upper step 3 is completed for the distance of 6 arch frames, the lower step 4 is started and the corresponding initial support construction is completed, including: the lower step arch foot steel support 5A and the lower step temporary vertical support steel support 5B. Then the upper and lower steps are advanced synchronously. The advance of each cycle of the lower step is not more than the distance between 2 arch frames. The arch foot of the upper step is strictly prohibited from being suspended in the air.

[0052] Step 5, after the initial support of the lower step 4 is completed with 3 arch frames, the inverted arch is excavated. The inverted arch frame is connected to the arch frame of the lower step 4 by bolts. The inverted arch 6 is only set at the oblique position section, and the single excavation is not more than 3m;

[0053] Step 6: After the initial support of the oblique intersection section is completed, the upper step 3 and the lower step 4 are synchronously constructed according to the normal section for 10m and then suspended to ensure that the lower step is 10m away from the oblique intersection;

[0054] Step 7, before excavating the equal-section tunnel II, a portal frame at an oblique position is constructed. The portal frame is composed of a vertical beam 10 and a horizontal beam 8. Both the vertical beam 10 and the horizontal beam 8 are made of I20 I-beams. The horizontal beam 8 is composed of 3 units, and the vertical beam 10 is composed of 2 units. The vertical beam 10 and the horizontal beam 8 are connected by bolts. During the construction of the portal frame, the diagonal brace of the equal-section tunnel I needs to be removed. During the removal process, pay attention to the protection of the connected arch frames;

[0055] Step 8, after the construction of the portal frame is completed, the arc-shaped arch frame 11 in the portal frame is constructed, and an oblique I-beam is arranged on the upper part of the arc-shaped arch frame 11 to be connected with the portal frame, and the connection method at this position is welding;

[0056] Step 9, after the arc-shaped arch 11 completes the support, start the excavation of the equal-section tunnel II at the oblique position, adjust the section, the short side arch spacing is 0.5m, and the long side arch spacing is 1m. Before excavation, the upper step temporary vertical support steel support 2D and the lower step temporary vertical support steel support 5B of the initial support of the equal-section tunnel I within the gantry range need to be dismantled, and the dismantling is done mechanically.

[0057] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for oblique top selection of a tunnel with a uniform cross section, characterized in that: Special-shaped arch frames are used at the intersection of equal-section tunnels. Each special-shaped arch frame has a different structural form according to the different angles of intersection with the line. At the same time, the structural stability of the oblique intersection is ensured by the setting of diagonal braces and portal frames. The specific steps include: Step 1: Before excavating the oblique intersection section of two equal-section tunnels, advance measures are set for the surrounding rock within the upper step (3) of the equal-section tunnel I and grouting reinforcement treatment is carried out, and an advance support (1) is set above the surrounding rock; specifically: a φ60mm advance middle pipe shed is set within the upper step (3) of the equal-section tunnel I, 9m / root, lap length of 3m, annular spacing of 50cm, and the external insertion angle of the pipe shed is controlled at 1° to 3°. After the construction is completed, drilling is performed to verify the grouting effect before excavation; Step 2, after the construction of the advanced support (1) is completed, the tunnel is excavated, and after the upper step (3) is excavated, the concrete is initially sprayed to complete the initial support of the upper step, which includes: the upper step arch foot steel support (2A), the upper step arch waist steel support (2B), the upper step arch top steel support (2C) and the upper step temporary vertical support steel support (2D) four units; specifically: the excavation adopts the two-step reserved core soil plus milling excavation method, and the excavation distance of each cycle is not more than the distance of 2 arch frames. After the excavation of the upper step 3 is completed, 5 cm thick sprayed concrete is used in time to complete the closure. The upper step adopts I18 steel arch frame to strengthen the support, with a spacing of 0.8m. M27 high-strength bolts are used to connect the units, and φ22mm threaded steel bars are used to strengthen the connection between the arch frames. At the same time, the construction of the locking foot anchor pipe is strengthened and grouting is reinforced. The locking foot is a φ42mm steel flower pipe with a length of 4m / root; Step 3, after completing the initial support of the upper step (3) with two arch frames, suspend the operation and start the reinforcement construction of the diagonal brace (9), the diagonal brace (9) is an I18 steel arch frame, which strengthens the load bearing capacity of the right-angled part of the initial support of the upper step (3); Step 4, after the upper step (3) is constructed to complete the initial support of 6 arch frames, the lower step (4) is constructed and the corresponding initial support construction is completed, including: two units: the lower step arch foot steel support (5A) and the lower step temporary vertical support steel support (5B), and then the upper and lower steps are promoted synchronously; the left and right sides of the lower step should be staggered for excavation, and the staggered distance should not be greater than 2 arch frames, and the upper step arch foot is strictly prohibited from being suspended in the air; Step 5, after the initial support of the lower step (4) is completed with three arch frames, the inverted arch (6) is excavated, and the inverted arch (6) is set only in the oblique position section, and the single excavation is not greater than the threshold of 3m, and the steel arch frame is used to close the ring; Step 6: After the initial support of the oblique intersection section is completed, the upper step (3) and the lower step (4) are synchronously constructed according to the normal section for 10m and then suspended to ensure that the lower step is 10m away from the oblique intersection; Step 7, constructing a portal frame at an oblique position. When constructing the portal frame, the oblique support (9) of the equal-section tunnel I needs to be removed; Step 8, after the construction of the portal frame is completed, an arc-shaped arch frame (11) is constructed inside the portal frame, and an oblique I-beam is arranged on the upper part of the arc-shaped arch frame to be connected with the portal frame, and the connection method is welding; Step 9, after the arc-shaped arch frame (11) completes the support, the excavation of the equal-section tunnel II at the oblique position begins. Due to the unequal distances between the left and right sides of the adjustment section, the arch frame spacing is set with a non-equidistant setting until the adjustment is completed. Before excavation, the initial support lower step temporary vertical support steel support (5B) and upper step temporary vertical support steel support (2D) of the equal-section tunnel I within the gantry range are removed; the initial support arch frame of the equal-section tunnel I within the gantry range is the vertical unit part of the special-shaped arch frame, namely the upper step temporary vertical support steel support (2D) and the lower step temporary vertical support steel support (5B); the initial support of the adjustment section, the short side arch frame spacing is 0.5m, and the long side arch frame spacing is 1m; Step 10: Strengthen monitoring and measurement during the construction process to ensure that the cumulative deformation of the initial support is not greater than the threshold, and the deformation rate after the ring is closed is not greater than the threshold, that is, to carry out waterproof structure construction and follow up the subsequent lining construction in a timely manner.

2. The method for oblique top-lifting of a tunnel with a uniform cross-section according to claim 1 is characterized in that: The initial support includes: steel arch frame, longitudinal connecting steel bars, locking anchor pipes, system anchor rods, steel mesh and shotcrete.

3. The method for oblique top-lifting of a tunnel with a uniform cross-section according to claim 1 is characterized in that: In step 7, the door frame is composed of a vertical beam (10) and a horizontal beam (8), both of which are made of I-beams, the horizontal beam (8) is composed of 3 units, and the vertical beam (10) is composed of 2 units. The vertical beam (10) and the horizontal beam (8) are connected by bolts.

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