Cast-in-place supporting system for shallowly-buried shield tunnel after segment breaking

Abstract

The utility model belongs to the technical field of shield tunnel engineering, and particularly relates to a cast-in-place supporting system after shallowly-buried shield tunnel duct pieces are broken, which comprises a plurality of groups of hexagonal steel frame supporting structures, primary supporting arch cover structures and cast-in-place secondary lining structures. Wherein the hexagonal steel frame supporting structure is composed of vertical supports, cross beams, splayed inclined struts, inclined strut connecting pieces, diagonal bracings, steel base plates and arc-shaped rubber pads, the vertical supports, the cross beams, the diagonal bracings, the steel base plates and the arc-shaped rubber pads are connected into a whole through longitudinal connecting beams and the diagonal bracings, the primary supporting arch cover is composed of a steel arch frame, a reinforcing mesh, feet-lock bolts, sprayed concrete and the like, and the cast-in-place secondary lining serves as a permanent stress supporting structure. The construction technology is mature, the feasibility is high, the reliability is high, the hexagonal steel frame supporting structure can also be used for shield segment trepanning and a temporary reinforcing structure for preventing a segment structure from being deformed and damaged, on-site assembly is easy, cyclic utilization can be achieved, cost is effectively saved, work efficiency is improved, and the construction period is shortened. And the construction safety is ensured, and the influence of construction operation is reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to shield tunnel engineering technical field, especially relate to a kind of support system of shallow shield tunnel segment breaked post cast-in-situ. BACKGROUND

[0002] City subway tunnel often adopts shield method construction, for part line bifurcation, set fan equipment non-standard section is expanded on the basis of standard shield tunnel section, or due to jacking load too large and lead to segment cracking or construction error causes segment deviation invasion limit, usually need to break the segment that has assembled again cast-in-situ secondary lining to form permanent support structure.But for shallow shield tunnel, break the original tunnel segment to cast-in-situ secondary lining bear surrounding rock pressure stage, how to avoid the risk of falling of segment of removal section, ensure the stress safety of adjacent segment and the stability of tunnel surrounding rock and the safety of upper adjacent building structure, is the most important in the whole construction process.The conventional well-shaped, annular temporary steel support is flexible, but well-shaped middle space is limited, not convenient for mechanical construction, annular is disconnected and invalid, and it is not convenient to remove segment in sections, and it is not suitable for the working condition of breaking original segment by construction machinery.In view of this, the utility model provides a kind of support system of shallow shield tunnel segment breaked post cast-in-situ. UTILITY MODEL CONTENT

[0003] The utility model aims at the problems in the background art, and provides a kind of support system of shallow shield tunnel segment breaked post cast-in-situ.

[0004] The utility model discloses a kind of support system of shallow shield tunnel segment breaked post cast-in-situ, including the multiple groups of hexagonal steel frame support structure of being set in shield segment breakage position, for the temporary support reinforcement of shield segment of breakage position;Primary support arch cover structure is set in the shield segment removal position, for the temporary support of tunnel upper surrounding rock;Cast-in-situ secondary lining structure is set in the inner side of the primary support arch cover structure, for the permanent support of the tunnel surrounding rock of the shield segment breakage position.

[0005] The hexagonal steel frame support structure described in the utility model is composed of two cross beams, four eight-shaped diagonal braces, two diagonal brace connectors and multiple groups of vertical supports, scissors, steel backing plate and rubber pad;The upper and lower two cross beams and the four diagonal braces therebetween form a hexagonal portal, and the upper diagonal brace and the lower diagonal brace are firmly connected by the diagonal brace connector;The side of the cross beam close to the shield segment is fixedly connected with multiple groups of vertical supports, and scissors are arranged between the adjacent two groups of vertical supports;The end of the cross beam and the vertical support close to the shield segment is fixedly connected with steel backing plate abutting the inner wall of the shield segment, and arc-shaped rubber pad is arranged between the diagonal brace connector and the steel backing plate and the shield segment as buffer pad.

[0006] The multiple sets of hexagonal steel frame support structures are arranged at intervals along the tunnel direction and are not less than two at each end of the segment breaking range, six longitudinal connecting beams are connected between the adjacent two sets of hexagonal steel frame support structures, the upper and lower four longitudinal connecting beams are connected with the cross beams, the middle two longitudinal connecting beams are connected with the diagonal support connecting pieces, and the upper cross beams and the middle vertical supports above the upper cross beams are connected through the scissors supports, so that the overall rigidity is improved.

[0007] The primary support arch cover structure is composed of a steel arch, a steel mesh, a locking foot anchor rod and sprayed concrete, and system anchor rods, advanced small catheters and surrounding rock grouting reinforcement measures are arranged.

[0008] The waterproof layer is arranged between the cast-in-place secondary lining structure and the primary support arch cover structure, and is effectively connected with the adjacent shield segment along the longitudinal direction of the tunnel.

[0009] Optionally, the vertical supports and the cross beams, the diagonal supports and the cross beams, the diagonal supports and the diagonal support connecting pieces, the longitudinal connecting beams and the cross beams and the diagonal support connecting pieces can be connected through welding or bolt connection.

[0010] Optionally, the spacing between the multiple sets of hexagonal steel frame support structures can be adjusted according to the segment breaking range, and for the opening of the auxiliary structure such as the communication passage, the tunnel ventilation well and the rainwater pump house, the hexagonal steel frame support structure can be arranged on both sides of the opening and be densified and strengthened.

[0011] Optionally, the multiple sets of hexagonal steel frame support structures can also be used in the case that the overload above the super-shallow buried shield tunnel is large and may have adverse effects on the shield tunnel segment.

[0012] Optionally, when the bearing capacity of the arch foot rock-soil body of the primary support arch cover is insufficient or the stability of the rock-soil body at the lower part of the tunnel is poor, the arch foot of the primary support arch cover structure can be lowered to the bottom of the tunnel or closed into a ring.

[0013] In summary, the present application has the following at least one beneficial technical effect:

[0014] The support system has the advantages of simple structure, less material, mature construction technology, high work efficiency, strong implementability, simple on-site assembly of the hexagonal steel frame support structure, guaranteed construction passage through the middle passage, reduced influence of the support structure on construction machinery, recycling, effective cost saving, applicability to multiple working conditions such as shield segment breaking, shield segment opening and shield segment protection, and strong applicability and practicality.

[0015] Meanwhile, the safety risks during the shield segment demolition process are controllable, reducing the impact of the original tunnel shield segment demolition on the deformation of the surrounding rock and nearby buildings; for the demolition of shield segments with a narrow ring width, the spacing of the temporary support system can be appropriately adjusted to ensure that the shield segments are completely demolished and can be reused. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the support system of this utility model;

[0017] Figure 2 This is a top view of the support system of this utility model;

[0018] Figure 3 This is a longitudinal sectional view of the support system of this utility model;

[0019] Figure 4 This is a detailed drawing of the contact between the support and the tunnel segment of this utility model;

[0020] Figure 5 This is a construction flowchart of the support system of this utility model.

[0021] Figure label:

[0022] 1. Shield tunnel segments; 2. Vertical supports; 3. Horizontal beams; 4. Diagonal braces; 5. Diagonal brace connectors; 6. Scissor braces; 7. Rubber pads; 8. Steel pads; 9. Longitudinal connecting beams; 10. Initial support arch structure; 11. Anchor bolts; 12. Cast-in-place secondary lining structure. Detailed Implementation

[0023] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are preferred embodiments of this utility model, but not all embodiments.

[0024] Example

[0025] like Figures 1 to 5 As shown, this embodiment illustrates the support system used for cast-in-place secondary lining during the segment removal of a shallow-buried single-track shield tunnel in a Chongqing rail transit section. In the implemented project, the shield tunnel segments had an inner diameter of 7.7m, a thickness of 0.4m, and a ring width of 1.8m. Two rings of segments, due to upward deformation and encroachment, formed significant misalignments with adjacent segments that could not be corrected. To ensure construction quality and meet track laying and operational requirements, these two rings of segments were removed, and cast-in-place secondary lining was used as the permanent support structure. To ensure construction safety and reduce operational impact, based on project requirements, an analysis and research were conducted, and a support system and construction method suitable for cast-in-place secondary lining during the segment removal of shallow-buried shield tunnels was proposed, implemented, and verified.

[0026] In this embodiment, the diagonal brace 4 and the diagonal brace connecting piece 5 of the hexagonal steel frame support structure adopt HW250x250 steel, the cross beam 3, the vertical support 2 and the longitudinal connecting beam 9 adopt HW200x200 steel, the scissors brace 6 adopts #10 channel steel, the steel pad 8 adopts 300x200x20mm, and they are all connected by welding, and the steel pad 8 and the pipe piece 1 are connected by a 10mm thick rubber pad 7. The specific scheme is as follows:

[0027] In this embodiment, the hexagonal steel frame support structure includes two groups of upper and lower cross beams 3, and 7 and 5 vertical supports 2 are arranged between the upper and lower cross beams 3 and the shield pipe piece 1 respectively, and scissors braces 6 are arranged between the adjacent two groups of vertical supports 2 to improve the overall connectivity; four groups of diagonal braces 4 are arranged between the upper and lower cross beams 3, and the connecting point shaft distance of the diagonal brace and the cross beam is 3.45m, the upper diagonal brace and the lower diagonal brace are connected and fixed by the arc-shaped diagonal brace connecting piece 5 arranged near the tunnel transverse axis and fitted with the inner wall of the pipe piece, and together form a hexagonal portal. The end of the vertical support 2 and the cross beam 3 close to the shield pipe piece 1 is welded with the steel pad 8 fitted with the inner wall of the pipe piece, and the steel pad 8 and the diagonal brace connecting piece 5 are connected with the shield pipe piece 1 by the arc-shaped rubber pad 7 as a buffer pad. The hexagonal steel frame support structure is arranged in six groups along the tunnel direction, two groups are arranged in the breaking range of the shield pipe piece 1, and two groups are arranged at both ends of the breaking range, and the longitudinal distances are 1.8m, 1.7m, 1.7m, 2m and 1.8m respectively, and the pipe piece is broken from the 2m interval first during construction. Two adjacent hexagonal steel frame support structures are connected by six longitudinal connecting beams 9, two longitudinal connecting beams 9 are arranged between the upper and lower cross beams 3 and connected with the cross beam 3 at the end of the diagonal brace 4, and the middle two longitudinal connecting beams 9 are connected with the diagonal brace connecting piece 5, and the upper cross beams 3 and the middle vertical supports 2 above them are connected by scissors braces (6) to improve the overall stiffness.

[0028] In this embodiment, the primary support arch cover structure 10 installed at the position of the shield pipe piece 1 is made of type 14 steel + φ8@200x200 steel mesh + 210mm thick C25 sprayed concrete, and two C22 lock foot anchor rods 11 are arranged at each arch foot. It should be noted that the arch foot of the primary support arch cover in the embodiment is in a medium weathered sandstone stratum, which has sufficient bearing capacity, so the primary support arch cover structure 10 + lock foot anchor rod 11 is used for support, and for the case where the bearing capacity of the rock mass at the arch foot is insufficient, the primary support arch foot can be lowered to the bottom of the tunnel or closed into a ring.

[0029] In this embodiment, the cast-in-place secondary lining structure 12 arranged inside the primary support arch cover structure 10 is implemented after the shield pipe piece 1 is broken, the primary support arch cover structure 10 is completed, and the lower rock mass is closed. First, lay a waterproof layer, then bind the steel reinforcement cage, and then pour the secondary lining concrete. It should be noted that the cast-in-place secondary lining structure 12 is connected reliably along the tunnel longitudinal direction and the adjacent shield pipe piece by 19 bolts.

[0030] In the embodiment, the pipe segment breaking range is adjacent to an existing underground overpass, the vertical clearance is about 1.3 m, there is no system anchor rod, advanced small guide pipe or advanced pipe shed, and the overburden of the tunnel vault is 1 m thick medium weathered sandy mudstone + 3 m thick strong weathered sandy mudstone, so the grouting reinforcement effect is low, and therefore no advanced reinforcement measures are used in the embodiment. It should be noted that when the conditions permit and the actual working conditions require, support measures such as system anchor rods, advanced small guide pipes or pipe sheds, and grouting reinforcement should be used to ensure construction safety.

[0031] During construction of the embodiment, first, a hexagonal steel support structure is erected according to the design drawings, then the upper half of the pipe segments of the first ring of pipe segments in the longitudinal half ring is broken, and the primary support arch cover structure 10 is timely constructed; then the upper vertical supports 2 of the hexagonal steel support structure are removed and the crown of the remaining half ring of pipe segments is broken, then the upper cross beams 3 and the upper diagonal braces 4 are removed and the spandrel pipe segments are broken, and the primary support arch cover structure 10 is timely constructed; then the remaining lower steel support structure is removed, the lower pipe segment structure is broken, and the rock surface is closed. The above construction steps are repeated to remove the second ring of pipe segments, and after the pipe segment breaking work is completed, the waterproof layer is laid, the steel reinforcement cage is tied, and the cast-in-place secondary lining concrete is formed to form a permanent structure.

[0032] The above specific embodiments are only optional embodiments of the present application, and based on the technical solutions of the present application and the related inspiration of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments, which should all be included in the protection scope of the present application.

Claims

1. A support system for post-construction of a shallow-buried shield tunnel segment, characterized in that: It comprises multiple sets of hexagonal steel support structures and primary support arch cover structures (10), cast-in-situ secondary lining structures (12); The multiple sets of hexagonal steel support structures arranged at the breaking position of the shield segment (1) are used for temporarily supporting and reinforcing the shield segment (1) at the breaking position. The primary support arch cover structures (10) arranged at the breaking position of the shield segment (1) are used for temporarily supporting the surrounding rock above the tunnel at the breaking position. The cast-in-situ secondary lining structures (12) arranged inside the primary support arch cover structures (10) are used for long-term supporting of the surrounding rock at the breaking position.

2. The support system for the cast-in-place segment of a shallow-buried shield tunnel according to claim 1, characterized in that: The hexagonal steel support structures comprise upper and lower cross beams (3), multiple vertical supports (2) are fixedly connected to one side of the cross beams (3) close to the shield segment (1), a scissor brace (6) is arranged between adjacent two vertical supports (2), two inclined braces (4) are fixedly connected to opposite sides of the two cross beams (3), respectively, the inclined braces (4) are fixedly connected by the inner wall inclined brace connecting pieces (5) between the upper and lower inclined braces (4), and the two cross beams (3) and the four inclined braces (4) form a hexagonal portal.

3. The support system for post-construction of a shallow-buried shield tunnel segment according to claim 2, characterized in that: The cross beams (3) and the vertical supports (2) are connected to the steel backing plates (8) close to the inner wall of the shield segment (1), and the inclined brace connecting pieces (5) and the steel backing plates (8) are provided with arc-shaped rubber pads (7) between the inclined brace connecting pieces (5) and the steel backing plates (8) and the shield segment (1).

4. The support system for the cast-in-place segment of a shallow-buried shield tunnel according to claim 1, wherein: The multiple sets of hexagonal steel support structures are arranged along the tunnel direction at intervals and are not less than two sets at each end of the segment breaking range, two adjacent sets are connected by six longitudinal connecting beams (9), the upper and lower four longitudinal connecting beams (9) are connected to the cross beams (3), the middle two longitudinal connecting beams (9) are connected to the inclined brace connecting pieces (5), and the upper cross beams (3) and the middle vertical supports (2) above the upper cross beams (3) are connected by the scissor braces (6) to improve the overall rigidity.

5. The support system for post-construction of a shallow-buried shield tunnel segment according to claim 1, characterized in that: The primary support arch cover structures (10) are composed of steel arches, steel mesh sheets, locking foot anchor rods (11) and sprayed concrete, and are provided with system anchor rods, advanced small guide pipes and grouting reinforcement measures.

6. The support system for post-construction of a shallow-buried shield tunnel segment according to claim 1, characterized in that: The cast-in-situ secondary lining structures (12) are provided with waterproof layers between the cast-in-situ secondary lining structures (12) and the primary support arch cover structures (10), and are reliably connected between the cast-in-situ secondary lining structures (12) and the adjacent shield segments (1) along the longitudinal direction of the tunnel.

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