Excavation process for cross tunnel with same size and large cross section

Abstract

The invention relates to the technical field of tunnel construction, in particular to S1, construction of a normal section of an advanced tunnel; the construction method comprises the following steps: constructing a preceding tunnel to an intersection influence area according to a standard section, reinforcing the standard section close to the intersection influence area, adjusting the distance between arch frames from 1m to 0.8 m, and providing a stable foundation for construction of a transition section; s2, construction of an advanced tunnel transition section; after excavation is carried out circularly to the arch camber point of the intersection, top-lifting construction is carried out, the top-lifting footage of each cycle is 0.8 m, the top-lifting height is 0.3 m, excavation is carried out downwards to the standard section after passing through the midline of the intersection, and the overall maximum top-lifting height reaches 3 m; s3, excavating and supporting a backward tunnel horsehead; and the following tunnel enters from the side wall of the preceding tunnel through a hole. The method has the technical effect of solving the problems of support interruption and stress concentration.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to an excavation process for large cross-section cross tunnels with the same size. Background Art

[0002] In the traditional cross construction method, after the initial support (steel frame + anchor rod + shotcrete + steel mesh) is completed for the first tunnel in the normal section, the excavation of the second tunnel is carried out. Figure 1 As a schematic diagram of the traditional construction method for the steel frame of large-size equal-section orthogonal tunnel excavation, the distance between adjacent two arch frames in the normal section of the first tunnel is 1 m. When the second tunnel is excavated to the intersection area, all the steel frames in the arch part of the first tunnel need to be cut off. According to the intersection line, different lengths of each steel frame are reserved, and the steel frame of the second tunnel is welded to the remaining steel frame of the first tunnel to form a "hui" - shaped connection.

[0003] The traditional cross construction method has the following problems: 1. Damage to the integrity of the support system: A large number of steel frames in the arch part of the first tunnel are cut off, and the arch part forms a petal shape (four petals). Half of the area needs secondary excavation and secondary support to form the clearance and support of the second tunnel, and the other half area is reserved as the clearance and support of the first tunnel, destroying the continuity of the support system.

[0004] 2. Severe stress concentration phenomenon: The arch part in the intersection area is the intersection of two arc sections. After the steel frames at the intersection line are cut off and the steel frames of the second tunnel are welded, serious stress concentration will occur here, and plastic deformation is likely to occur. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides an excavation process for large cross-section cross tunnels with the same size that can ensure the continuity of the support system and no stress concentration phenomenon. The excavation process for large cross-section cross tunnels with the same size provided by the present invention adopts the following technical solutions: S1. Construction of the normal section of the first tunnel; The first tunnel is constructed in the standard section to the intersection influence area, and the standard section near the intersection influence area is strengthened. The arch frame spacing is adjusted from 1 m to 0.8 m to provide a stable foundation for the construction of the transition section. S2. Construction of the transition section of the first tunnel; After excavating to the intersection springing point in each cycle, top-heading construction is carried out. The top-heading advance per cycle is 0.8 m, and the top-heading height is 0.3 m. After passing the intersection center line, excavation is carried out downward to the standard section, and the overall maximum top-heading height reaches 3 m. S3. Excavation and support of the adit of the second tunnel; The second tunnel enters through a hole opened in the side wall of the first tunnel.

[0006] Compared with the prior art, the present invention has the following technical effects: The construction process of this invention comprehensively considers the height and span of the intersection of the preceding tunnels, gradually raising the intersection section of the preceding tunnels to avoid damage to the preceding tunnels during the excavation of the subsequent tunnels and reduce safety risks. The arch frames of the preceding tunnels are raised segment by segment, with each arch frame raised by 0.3m, reaching a 3m height at the top of the subsequent tunnel, creating a height difference between the preceding and subsequent tunnels. This eliminates the need to remove the arch frames from the arch section during the excavation of the subsequent tunnel, thus reducing safety risks. The construction process of this invention, through the segment-by-segment adjustment of the arch raising line, allows the subsequent tunnel to open through the sidewall of the preceding tunnel, completely preserving the arch support system and solving the core problems of "support interruption and stress concentration" in traditional methods. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the prior art of this invention; Figure 2 This is a schematic diagram of the preceding tunnel, the following tunnel, and the intersection influence zone in this invention. Figure 3 This is a schematic diagram of the arch frame structure in the cross-influence zone of this invention.

[0008] Explanation of the attached diagram labels: 1. Leading tunnel; 11. Intersection impact area; 2. Following tunnel. Detailed Implementation

[0009] The following is in conjunction with the appendix Figure 1 -Appendix Figure 3 The present invention will be described in further detail below.

[0010] This invention discloses a process for excavating a cross-shaped tunnel of the same size and cross section, comprising the following steps: S1, Construction of the normal section of the first tunnel; The first tunnel 1 was constructed according to the standard cross-section up to the intersection influence zone 11. The standard cross-section near the intersection influence zone 11 was reinforced, and the arch spacing was adjusted from 1m to 0.8m to provide a stable foundation for the construction of the transition section.

[0011] S2, construction of the transition section of the first tunnel; After excavating to the arching point of the intersection in successive cycles, the jacking construction is carried out. Each cycle of jacking advances 0.8m and raises 0.3m. After passing the center line of the intersection, the excavation is carried out downward to the standard cross section. The overall maximum jacking height reaches 3m.

[0012] The excavation is carried out cascade by cascade, with the distance between one arch frame being excavated before the distance between the next arch frame is excavated. The arch frame spacing at the intersection is 0.8m, the highest point of the subsequent arch frame is 0.3m higher than the highest point of the previous arch frame, and the height difference between the highest point of the arch frame at the starting point and the highest point of the arch frame at the center line of the intersection is 3m.

[0013] S3, Excavation and support of the second gate of the rear tunnel; The second tunnel is accessed by opening a hole in the side wall of the first tunnel.

[0014] The construction process of this invention comprehensively considers the height and span of the intersection of the first tunnel 1. The intersection section of the first tunnel 1 is gradually raised to avoid damage to the first tunnel 1 during the excavation of the subsequent tunnel 2, thus reducing safety risks. The arch frames of the first tunnel 1 are raised segment by segment, with each segment raised by 0.3m, reaching a height of 3m at the top of the subsequent tunnel. This creates a height difference between the first tunnel 1 and the subsequent tunnel 2, eliminating the need to remove the arch frames from the arch section during the excavation of the subsequent tunnel, thereby reducing safety risks.

[0015] The construction process of this invention, through adjusting the arching line of each tunnel segment, enables the subsequent tunnel 2 to open from the side wall of the preceding tunnel 1, thus completely preserving the arch support system and solving the core problems of "support interruption and stress concentration" in traditional solutions.

[0016] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for excavating large-section cross-shaped tunnels of the same size, characterized in that: S1. Construction of the normal section of the tunnel in advance; The initial tunnel was constructed according to the standard cross-section up to the intersection impact zone. The standard cross-section near the intersection impact zone was reinforced, and the arch spacing was adjusted from 1m to 0.8m to provide a stable foundation for the construction of the transition section. S2, Construction of the transition section of the initial tunnel; After excavating to the arching point of the intersection in successive cycles, the jacking construction is carried out. Each cycle of jacking advances 0.8m and raises 0.3m. After passing the center line of the intersection, the excavation is carried out downward to the standard cross section. The overall maximum jacking height reaches 3m. S3, Excavation and support of the rear tunnel's gate; The subsequent tunnel is accessed by opening a hole in the side wall of the preceding tunnel.

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