Supporting arch and lining cooperative bearing structure for tunnel soft rock deformation tunnel section and construction method

Abstract

The invention provides a tunnel soft rock deformation tunnel section protection arch and lining cooperative bearing structure and a construction method. The structure comprises a primary support, a protection arch and a lining. The protection arch comprises a plurality of steel supports which are sequentially arranged on the inner side of the primary support at intervals in the longitudinal direction. The lining is of a reinforced concrete structure, and a reinforcing steel bar system of the lining comprises (1) circumferential reinforcing steel bars distributed on the outer side and the inner side of the lining, and the circumferential reinforcing steel bars on the outer side avoid when meeting a protective arch; (2) longitudinal steel bars are divided into outer side longitudinal steel bars and inner side longitudinal steel bars, the outer side longitudinal steel bars are arranged close to the inner side of the protective arch, and the inner side longitudinal steel bars abut against the inner side annular main steel bars; and (3) U-shaped steel bars are arranged between the two adjacent truss guard arches, and the two ends of each U-shaped steel bar are bent inwards and connected with the longitudinal steel bars on the inner side, so that the lining steel bar system and the guard arches form a whole. The problem that the lining cannot be normally constructed due to the fact that the lining space is occupied after the protection arch is constructed can be solved.

Description

Technical Field

[0001] This invention relates to the field of tunnel arch construction technology, and in particular to a collaborative load-bearing structure and construction method for arch and lining in soft rock deformation sections of tunnels. Background Technology

[0002] In tunnel engineering, especially in high-stress soft rock formations, the deformation and encroachment of surrounding rock is a common technical challenge. In traditional tunnel construction, when the deformation rate of the tunnel is too rapid after the initial support, steel arches (i.e., protective arches) are usually added for reinforcement to suppress further deformation. However, this remedial measure brings new problems: the protective arches encroach on the space for subsequent lining, making it impossible to construct the secondary lining to the designed thickness.

[0003] Currently, there are two main solutions for dealing with the encroachment of the arch on the lining space: one is to widen the excavation and replace the arch, but this method has high operational risks, long construction period, and high cost; the other is to directly cast the arch into the lining, but the arch and the lining reinforcement intersect and interfere with each other, making it difficult to form an effective overall load-bearing structure. In actual engineering, when the outer longitudinal reinforcement encounters the arch, it is usually cut off or moved inward as a whole. However, cutting off destroys the continuity and integrity of the longitudinal reinforcement of the lining, while moving inward as a whole results in the inability to effectively overlap with the main load-bearing reinforcement. Both of these methods are detrimental to the load-bearing performance of the lining structure and are prone to cracking under temperature shrinkage or longitudinal stress, seriously affecting the long-term safety and durability of the tunnel structure.

[0004] Therefore, there is an urgent need to develop a structural system and construction method that enables the arch support and lining to form a synergistic load-bearing structure, so as to solve the construction problems caused by the arch support encroaching on the lining space without replacing the arch, while ensuring the integrity and load-bearing capacity of the lining structure. Summary of the Invention

[0005] The purpose of this invention is to provide a structure and construction method for the coordinated bearing of arch support and lining in soft rock deformation tunnel sections, in order to solve the problem that the arch support encroaches on the lining space after construction, making it impossible to construct the lining normally.

[0006] To address the aforementioned technical problems, this invention provides a cooperative bearing structure for the arch and lining of a tunnel section prone to soft rock deformation, comprising: initial support, arch, and lining; the arch comprises multiple steel supports arranged longitudinally and at intervals on the initial support; the lining comprises outer longitudinal reinforcement arranged close to the inner side of the steel supports, inner longitudinal reinforcement arranged inside the outer longitudinal reinforcement, outer circumferential reinforcement arranged between the outer and inner sides of the steel supports, inner circumferential reinforcement arranged inside the inner longitudinal reinforcement, and U-shaped reinforcement arranged longitudinally between two adjacent steel supports, wherein the bottom of the U-shaped reinforcement is located between the inner and outer sides of the steel supports, and the two free ends of the U-shaped reinforcement are connected to the inner longitudinal reinforcement.

[0007] Optionally, the two free ends of the U-shaped steel bar are tied together at the intersection with the inner longitudinal steel bar.

[0008] Optionally, the bottom of the U-shaped steel bar is tied to the intersection of the outer circumferential steel bar.

[0009] Optionally, the steel support is an I-beam.

[0010] Optionally, the diameter of the U-shaped steel bar is the same as the diameter of the outer longitudinal steel bar.

[0011] The present invention also provides a construction method for a tunnel arch and lining co-bearing structure for soft rock deformation sections as described above, comprising: constructing initial support; constructing an arch, wherein the arch comprises multiple steel supports arranged sequentially at intervals along the longitudinal direction; arranging outer longitudinal reinforcement close to the inner side of the steel supports, and arranging inner longitudinal reinforcement inside the outer longitudinal reinforcement; arranging outer circumferential reinforcement between the outer and inner sides of the steel supports, and arranging inner circumferential reinforcement inside the inner longitudinal reinforcement; and arranging U-shaped reinforcement along the longitudinal direction between two adjacent steel supports, wherein the bottom of the U-shaped reinforcement is located between the inner and outer sides of the steel supports, and the two free ends of the U-shaped reinforcement are connected to the inner longitudinal reinforcement.

[0012] Optionally, after the initial support is constructed but before the arch is constructed, the following steps are taken: monitor tunnel deformation, and when the cumulative deformation value is close to the tunnel's reserved deformation amount and the deformation rate is greater than 0.2 mm / d, decide to construct the arch.

[0013] Optionally, after the initial support is constructed but before the arch is constructed, the following steps may be included: comparative analysis with the initial support design profile, and removal of locally encroaching shotcrete.

[0014] Optionally, the construction of the protective arch includes: cleaning out the base surface on the surface of the initially constructed support steel arch frame, erecting the protective arch steel arch frame circumferentially along its lower flange surface, and welding the protective arch to the flange of the initially constructed support steel arch frame firmly.

[0015] Optionally, pouring the lining concrete includes: setting up a formwork trolley, pouring secondary lining concrete to ensure that the arch and steel reinforcement skeleton are fully wrapped and compacted by the concrete; after the concrete has cured to the required strength, a complete arch and lining co-bearing structure for soft rock deformation tunnel sections is formed.

[0016] The present invention provides a collaborative load-bearing structure and construction method for arch support and lining in tunnel sections prone to soft rock deformation, which has the following beneficial effects: First, by moving the outer longitudinal reinforcement inward, i.e. arranging the outer longitudinal reinforcement close to the inner side of the steel support, and by arranging U-shaped reinforcements longitudinally between two adjacent steel supports, with the bottom of the U-shaped reinforcements located between the inner and outer sides of the steel support, and the two free ends of the U-shaped reinforcements connected to the inner longitudinal reinforcements, the problems of structural integrity and longitudinal stress cracking in the lining can be solved, improving the overall integrity of the lining structure. This ensures the quality of the project from the perspectives of mechanical performance and long-term safety, and significantly improves the structural bearing capacity.

[0017] Secondly, by pouring the protective arch into the lining concrete on the basis of ordinary reinforced concrete lining, the protective arch, the steel reinforcement skeleton, and the lining concrete form a joint load-bearing structure, avoiding replacement; due to the influence of the protective arch, it interferes with the outer longitudinal reinforcement and the outer circumferential reinforcement. Therefore, the outer longitudinal reinforcement is moved inward and the outer circumferential main reinforcement is avoided; after the outer longitudinal reinforcement is moved inward, it cannot be lapped with the main reinforcement, so U-shaped reinforcement is added for compensation. Attached Figure Description

[0018] Figure 1 This is a longitudinal cross-sectional schematic diagram of the tunnel arch and lining co-bearing structure in the soft rock deformation section of the present invention. Figure 2 This is a schematic diagram of the longitudinal section of the three-dimensional structure of the arch support and lining of the tunnel soft rock deformation section in this embodiment of the invention. Figure 3 This is a schematic diagram of the steel support and U-shaped steel reinforcement arrangement of the tunnel arch and lining collaborative bearing structure in the soft rock deformation section of the present invention. Figure 4 This is a schematic diagram of the reinforcement arrangement of the arch support and lining collaborative bearing structure in the soft rock deformation section of the tunnel in this embodiment of the invention; Figure 5 This is a partial cross-sectional schematic diagram of the tunnel arch and lining collaborative bearing structure in the soft rock deformation section of the present invention. Figure 6 This is a schematic diagram of the dimensions of the lining in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 100 - Steel support; 210 - Outer longitudinal reinforcement; 220 - Inner longitudinal reinforcement; 230 - Outer circumferential reinforcement; 240 - Inner circumferential reinforcement; 250 - U-shaped reinforcement. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 , Figure 1 This is a longitudinal cross-sectional schematic diagram of the tunnel arch and lining collaborative load-bearing structure in the soft rock deformation section of the present invention. Figure 2 This is a longitudinal cross-sectional three-dimensional structural diagram of the tunnel arch and lining collaborative load-bearing structure in the soft rock deformation section of the present invention. Figure 3 This is a schematic diagram of the steel support and U-shaped steel reinforcement arrangement of the tunnel arch and lining collaborative bearing structure in the soft rock deformation section of the present invention. Figure 4 This is a schematic diagram of the reinforcement arrangement of the arch support and lining in the tunnel soft rock deformation section according to an embodiment of the present invention. Figure 5 This is a partial cross-sectional schematic diagram of the tunnel arch and lining co-bearing structure in a soft rock deformation section of the present invention. This embodiment also provides a tunnel arch and lining co-bearing structure in a soft rock deformation section, comprising: initial support, arch, and lining. The arch includes multiple steel supports 100 arranged longitudinally and at intervals on the initial support. The lining includes outer longitudinal reinforcing bars 210 arranged close to the inner side of the steel supports 100, inner longitudinal reinforcing bars 220 arranged inside the outer longitudinal reinforcing bars 210, outer circumferential reinforcing bars 230 arranged between the outer and inner sides of the steel supports 100, inner circumferential reinforcing bars 240 arranged inside the inner longitudinal reinforcing bars 220, and U-shaped reinforcing bars 250 arranged longitudinally between adjacent steel supports 100. The bottom of the U-shaped reinforcing bars 250 is located between the inner and outer sides of the steel supports 100, and the two free ends of the U-shaped reinforcing bars 250 are connected to the inner longitudinal reinforcing bars 220.

[0027] By moving the outer longitudinal reinforcing bar 210 inward, that is, arranging the outer longitudinal reinforcing bar 210 close to the inner side of the steel support 100, and arranging U-shaped reinforcing bars 250 longitudinally between two adjacent steel supports 100, with the bottom of the U-shaped reinforcing bars 250 located between the inner and outer sides of the steel support 100, and the two free ends of the U-shaped reinforcing bars 250 connected to the inner longitudinal reinforcing bars 220, the problems of structural construction and longitudinal stress cracking of the lining structure can be solved, the integrity of the lining structure can be improved, the quality of the project can be guaranteed from the perspective of mechanical performance and long-term safety, and the structural bearing capacity can be significantly improved.

[0028] Open-type TBMs cannot accommodate sufficient deformation, and the arch support will encroach on the secondary lining outline after construction. The arch support (steel support 100) can be directly poured into the lining concrete to form a combined arch-lining load-bearing structure, solving the problem of insufficient lining space and improving the load-bearing capacity of the lining structure. However, pouring the arch support into the lining interferes with the reinforcement arrangement. Common practices in engineering practice involve directly cutting off the outer longitudinal reinforcement 210 or moving the outer longitudinal reinforcement 210 inwards. Cutting off the reinforcement disrupts the continuity and integrity of the longitudinal reinforcement, while moving it inwards prevents it from lapping with the main load-bearing reinforcement. Both of these methods are detrimental to the load-bearing capacity of the lining structure, leading to cracking under temperature shrinkage or longitudinal stress. This embodiment proposes the following solutions: ① The spacing of the outer circumferential reinforcing bars 230 is locally adjusted at the arch support position to avoid the arch support, ensuring that the outer circumferential reinforcing bars 230 meet the specifications and calculation requirements; ② The outer longitudinal reinforcing bars are moved inward to the bottom of the steel support 100 and laid close to the surface of the steel support 100 to ensure that the outer longitudinal reinforcing bars 210 are continuous throughout; ③ U-shaped reinforcing bars 250 are added to connect with the outer longitudinal reinforcing bars 210 and the inner longitudinal reinforcing bars 220 to form a skeleton, which together with the continuous longitudinal reinforcing bars provides longitudinal tensile bearing capacity, meeting the requirements of crack resistance and longitudinal bearing capacity of the lining concrete.

[0029] Preferably, the two free ends of the U-shaped steel bar 250 are tied together at the intersection with the inner longitudinal steel bar 220.

[0030] Preferably, the bottom of the U-shaped steel bar 250 is tied to the intersection of the outer circumferential steel bar 230.

[0031] Preferably, the steel support 100 is an I-beam.

[0032] The U-shaped steel bar 250 is mainly used to compensate for the structural problems caused by the inward displacement of the outer longitudinal steel bar 210, and its diameter is the same as that of the outer longitudinal steel bar 210.

[0033] refer to Figure 6 , Figure 6This is a schematic diagram of the lining dimensions in an embodiment of the present invention. During the lining construction in this embodiment, the dimensions of the outer longitudinal reinforcement 210, the inner longitudinal reinforcement 220, the outer circumferential reinforcement 230, the inner circumferential reinforcement 240, the U-shaped reinforcement 250, and the concrete protective layer are as follows: L h For steel supports, the spacing between 100mm supports should be ≥50cm. L gb The steel support should have a flange width of 100mm; it should not be too large. gb / L h It is advisable to have a value of ≤0.4; L gh The distance between the outer longitudinal reinforcing bar 210 and the outer contour of the lining is determined by the height of the steel support 100. H represents the lining thickness; L c For the thickness of the concrete protective layer L U1 The length of the U-shaped steel bar 250 along its longitudinal direction is equal to L. h -L gb ; L U2 The radial length of the U-shaped steel bar bent at 250mm is equal to the spacing of the inner and outer circumferential steel bars at 230mm: L U2 =H-2L c -2d, where d is the diameter of the circumferential main reinforcement.

[0034] In this embodiment, the protective arch acts as a rigid skeleton, primarily providing initial deformation suppression and later bending stiffness; the optimized and reconstructed steel reinforcement skeleton (circumferential main bars, inwardly shifted outer longitudinal bars, U-shaped bars, and inner longitudinal bars) provides circumferential and longitudinal tensile and crack resistance. Both work collaboratively under the protection of concrete, jointly bearing the surrounding rock pressure, forming a high-stiffness composite load-bearing system.

[0035] This embodiment also provides a construction method for a tunnel arch and lining collaborative load-bearing structure in soft rock deformation sections, including: Initial support during construction; Constructing a protective arch, the protective arch comprising multiple steel supports 100 arranged sequentially at intervals along the longitudinal direction; An outer longitudinal steel bar 210 is arranged close to the inner side of the steel support 100, and an inner longitudinal steel bar 220 is arranged inside the outer longitudinal steel bar 210. An outer circumferential steel bar 230 is arranged between the outer and inner sides of the steel support 100, and an inner circumferential steel bar 240 is arranged inside the inner longitudinal steel bar 220. A U-shaped steel bar 250 is arranged longitudinally between two adjacent steel supports 100. The bottom of the U-shaped steel bar 250 is located between the inner and outer sides of the steel support 100, and the two free ends of the U-shaped steel bar 250 are connected to the inner longitudinal steel bar 220. Pour the lining concrete.

[0036] By moving the outer longitudinal reinforcing bar 210 inward, that is, arranging the outer longitudinal reinforcing bar 210 close to the inner side of the steel support 100, and arranging U-shaped reinforcing bars 250 longitudinally between two adjacent steel supports 100, with the bottom of the U-shaped reinforcing bars 250 located between the inner and outer sides of the steel support 100, and the two free ends of the U-shaped reinforcing bars 250 connected to the inner longitudinal reinforcing bars 220, the problems of structural construction and longitudinal stress cracking of the lining structure can be solved, the integrity of the lining structure can be improved, the quality of the project can be guaranteed from the perspective of mechanical performance and long-term safety, and the structural bearing capacity can be significantly improved.

[0037] Preferably, the process includes the following steps after the initial support is applied and before the arch support is applied: Monitor tunnel deformation. When the cumulative deformation value approaches the tunnel's reserved deformation amount and the deformation rate is >0.2mm / d, decide to construct the arch support.

[0038] Preferably, after the initial support is constructed and before the arch is constructed, the following steps are also included: comparative analysis with the initial support design outline, and removal of locally encroaching shotcrete.

[0039] Preferably, the construction of the protective arch includes: cleaning out the base surface on the surface of the initially constructed support steel arch frame, erecting the protective arch steel arch frame circumferentially along its lower flange surface, and welding the protective arch to the flange of the initially constructed support steel arch frame firmly.

[0040] Specifically, an outer longitudinal reinforcing bar 210 is arranged close to the inner side of the steel support 100, and an inner longitudinal reinforcing bar 220 is arranged inside the outer longitudinal reinforcing bar 210. An outer circumferential reinforcing bar 230 is arranged between the outer and inner sides of the steel support 100, and an inner circumferential reinforcing bar 240 is arranged inside the inner longitudinal reinforcing bar 220. Furthermore, a U-shaped reinforcing bar 250 is arranged longitudinally between two adjacent steel supports 100, with the bottom of the U-shaped reinforcing bar 250 located between the inner and outer sides of the steel support 100. The two free ends of the U-shaped reinforcing bar 250 are connected to the inner longitudinal reinforcing bar 220. The following points should be noted: a. Tie the outer circumferential reinforcing bars 230 and the inner circumferential reinforcing bars 240 of the secondary lining, and locally adjust the spacing at the arch support position to make it avoid the steel support 100.

[0041] b. Lay the outer longitudinal steel bars 210 so that the outer longitudinal steel bars 210 are tightly attached to the inner surface of the steel support and ensure that they are continuous throughout the entire process, and then lay the inner longitudinal steel bars 220.

[0042] c. Install U-shaped reinforcing bars 250, with their bottom overlapping the outer circumferential reinforcing bars 230 and tied with steel wire. The two free ends cross the inner longitudinal reinforcing bars 220 respectively, and are tied firmly at the intersection, so that the U-shaped reinforcing bars 250, the outer circumferential reinforcing bars 230, the inner circumferential reinforcing bars 240, the outer longitudinal reinforcing bars 210 and the inner longitudinal reinforcing bars 220 together form a spatial reinforcing bar skeleton.

[0043] d. Complete the binding of the tie bars according to the design.

[0044] Pouring lining concrete includes: Erect the formwork trolley and pour the secondary lining concrete to ensure that the arch support and steel reinforcement skeleton are fully and densely wrapped by the concrete. After the concrete has cured to the required strength, it forms a complete support structure for the arch and lining of the tunnel section in soft rock deformation.

[0045] The following example illustrates the construction process of an open-face TBM used in a deep-buried, long-distance water conveyance tunnel through soft rock formations, with detailed explanations in conjunction with accompanying drawings and the actual construction flow. In this example, an open-face TBM with a cutterhead diameter of 9.83m is used in the tunnel; adjustments can be made for other projects based on actual conditions.

[0046] The tunnel section has a circular cross-section and an excavation diameter of 9.83m. Significant deformation occurred when it traversed a fractured zone. This fractured zone consists of granulite, siltstone interbedded with breccia and layered cataclastic rocks. The original rock was mainly mudstone and carbonaceous sandstone, with fractured rock blocks. The mudstone and shale are weak and easily softened by water. Due to the poor geological conditions and significant deformation of the surrounding rock, the relevant technical solution described in this embodiment was used for on-site treatment, as follows: Original design requirements 1. The initial support adopts a full-section H150 steel arch frame with a spacing of 0.5m. The shotcrete is C25 polypropylene coarse fiber concrete with a thickness of 15cm. Before applying the shotcrete, a steel mesh of A8.0@0.15m×0.15m is hung on the entire section.

[0047] 2. The lining is made of C30 reinforced concrete, 0.4m thick, and the reinforcement configuration is as follows: outer circumferential reinforcement and inner circumferential reinforcement C20@200, outer longitudinal reinforcement 210 and inner longitudinal reinforcement C14@200, and tie bars A8@400.

[0048] II. Handling of Large Deformation Problems in Initial Supports on Site During the construction of the open-face TBM, monitoring revealed that the cumulative deformation in the tunnel section with poor geological conditions reached 18cm, approaching the deformation limit, and the deformation rate was 1.1mm / d, greater than 0.2mm / d, indicating a significant risk of exceeding the limit. Emergency arch reinforcement measures were then initiated, and construction was carried out according to the method described in this invention. 1) Measure the cross-sectional profile and remove any encroaching shotcrete.

[0049] 2) Clean the base surface on the surface of the initial support steel arch frame that has been constructed to prepare for the installation of the arch support.

[0050] 3) I20a type steel arches are added to this section with a longitudinal spacing of 0.5m. The steel arches are erected circumferentially along the lower flange surface of the original initial support steel arch frame, and the arches are firmly welded to the flange of the initial support steel arch frame. 4) Tying the secondary lining reinforcement a. Tie the outer circumferential reinforcing bars 230 (C20@200) and the inner circumferential reinforcing bars 240 (C20@200) of the secondary lining. At the arch support position, locally adjust the spacing of adjacent outer circumferential reinforcing bars 230 to 25cm so that they avoid the steel support 100.

[0051] b. Lay the outer longitudinal steel bars 210 (C14@200) so that the outer longitudinal steel bars 210 are tightly attached to the inner surface of the steel support and are continuous throughout the entire length. Lay the inner longitudinal steel bars 220 (C14@200) along the longitudinal length of the lining section, and do not allow laps.

[0052] c. Install U-shaped reinforcing bars 250 (C14@200), with their bottom overlapping the outer circumferential reinforcing bars 230 and tied with steel wire. The two free ends cross the inner longitudinal reinforcing bars 220 respectively, and tie them firmly at the intersection, so that the U-shaped reinforcing bars 250, the outer circumferential reinforcing bars 230, the inner circumferential reinforcing bars 240, the outer longitudinal reinforcing bars 210 and the inner longitudinal reinforcing bars 220 together form a spatial reinforcing bar skeleton.

[0053] d. Complete the binding of the tie bars according to the design.

[0054] 5) After the mobile formwork trolley is in place and the reinforcing steel is inspected, C30 concrete is pumped for pouring. During vibration, ensure the compactness of the concrete at the bottom of the arch support and in areas with dense reinforcing steel.

[0055] 6) After the concrete has cured to the required strength, a complete arch-secondary lining combined load-bearing structure is formed.

[0056] 3. When the arch support and U-shaped steel reinforcement are arranged in the case where there is no remaining deformable space in the first layer of initial support (the arch support is completely poured into the lining), in actual construction, based on the cross-sectional re-measurement results before the lining is poured, the arrangement position of the U-shaped steel reinforcement can be adjusted according to the positional relationship between the arch support and the outer contour of the lining, provided that the lining thickness is met.

[0057] After the above treatment, the secondary lining was intact and no obvious cracks were found on the surface. No arch deformation exceeding the threshold was found in the adjacent tunnel sections. This proves that the treatment plan coordinated the arch protection and secondary lining arrangement, effectively controlled the large deformation of soft rock in this area, improved construction efficiency, and avoided the safety and investment risks caused by the replacement of the arch frame.

[0058] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A collaborative load-bearing structure for the arch support and lining of a tunnel section prone to soft rock deformation, characterized in that, include: Initial support, arch support and lining; The protective arch comprises multiple steel supports arranged longitudinally and at intervals on the initial support; The lining includes outer longitudinal reinforcement arranged close to the inner side of the steel support, inner longitudinal reinforcement arranged inside the outer longitudinal reinforcement, outer circumferential reinforcement arranged between the outer and inner sides of the steel support, inner circumferential reinforcement arranged inside the inner longitudinal reinforcement, and U-shaped reinforcement arranged longitudinally between two adjacent steel supports, wherein the bottom of the U-shaped reinforcement is located between the inner and outer sides of the steel support, and the two free ends of the U-shaped reinforcement are connected to the inner longitudinal reinforcement.

2. The tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 1, characterized in that, The two free ends of the U-shaped steel bar are tied together at the intersection with the inner longitudinal steel bar.

3. The tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 1, characterized in that, The bottom of the U-shaped steel bar is tied to the intersection of the outer circumferential steel bar and the bottom of the U-shaped steel bar.

4. The tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 1, characterized in that, The steel support is an I-beam.

5. The tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 4, characterized in that, The diameter of the U-shaped steel bar is the same as the diameter of the outer longitudinal steel bar.

6. A construction method for a tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in any one of claims 1-5, characterized in that, include: Initial support during construction; Constructing a protective arch, the protective arch comprising multiple steel supports arranged sequentially at intervals along the longitudinal direction; Outer longitudinal reinforcement bars are arranged close to the inner side of the steel support, and inner longitudinal reinforcement bars are arranged inside the outer longitudinal reinforcement bars. Outer circumferential reinforcement bars are arranged between the outer and inner sides of the steel support, and inner circumferential reinforcement bars are arranged inside the inner longitudinal reinforcement bars. U-shaped reinforcement bars are arranged longitudinally between two adjacent steel supports. The bottom of the U-shaped reinforcement bars is located between the inner and outer sides of the steel support, and the two free ends of the U-shaped reinforcement bars are connected to the inner longitudinal reinforcement bars.

7. The construction method of the tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 6, characterized in that, The process includes: after the initial support is installed and before the arch support is installed. Monitor tunnel deformation. When the cumulative deformation value approaches the tunnel's reserved deformation amount and the deformation rate is greater than 0.2 mm / d, decide to construct a protective arch.

8. The construction method of the tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 6, characterized in that, After the initial support is constructed and before the arch is constructed, the following steps are also included: comparative analysis with the initial support design outline, and removal of locally encroaching shotcrete.

9. The construction method of the tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 6, characterized in that, The construction of the protective arch includes: cleaning out the base surface on the surface of the initially constructed support steel arch frame, erecting the protective arch steel arch frame circumferentially along its lower flange surface, and welding the protective arch to the flange of the initially constructed support steel arch frame firmly.

10. The construction method of the tunnel arch and lining collaborative load-bearing structure for soft rock deformation sections as described in claim 6, characterized in that, Pouring lining concrete includes: Erect the formwork trolley and pour the secondary lining concrete to ensure that the arch support and steel reinforcement skeleton are fully and densely wrapped by the concrete. After the concrete has cured to the required strength, it forms a complete support structure for the tunnel arch and lining in the soft rock deformation section.

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