Tunnel prestressed adaptive yielding steel frame and construction method

Abstract

The present invention provides a tunnel prestressed adaptive yielding steel frame and a construction method, belonging to the technical field of tunnel engineering. The tunnel prestressed adaptive yielding steel frame includes a support frame body and an adaptable structure, and two adjacent sections of the support frame body are connected by means of the adaptable structure; the adaptable structure includes a prestressed device and a yielding device connected in sequence, and the prestressed device includes a prestressed release structure with a tendency to elongate along its length direction; the yielding device includes a yielding support structure with a tendency to buckle along its length direction; the prestress of the prestressed release structure is less than the yielding starting force of the yielding support structure. The tunnel prestressed adaptive yielding steel frame provided by the present invention utilizes the release of the prestressed release structure to apply a supporting force to the surrounding rock to form an active supporting force; utilizes the compression deformation of the yielding support structure and the retraction of the prestressed release structure to bear the surrounding rock pressure; realizes the effective combination of the prestressed device and the yielding device, and improves the stability of the support structure.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering, and more specifically, relates to a tunnel prestressed adaptive yielding steel frame and a construction method. Background Art

[0002] With the construction of the western transportation network in my country, more and more tunnel projects are being built in complex geological sections. The surrounding rock collapse and support structure cracking and deformation caused by tunnels with weak surrounding rock and large deformation have become one of the major engineering problems faced by tunnel construction. In the face of large deformation problems of tunnels, yield support has become an important support measure to solve large deformation of tunnels. Existing tunnel support measures include: double-layer support, single-layer yield support and other forms. However, the existing yield support is mostly passive support, and it is impossible to combine prestressed supports and yield supports, and it cannot meet the stability requirements of the support structure. Summary of the invention

[0003] The object of the present invention is to provide a tunnel prestressed adaptive pressure-yielding steel frame and a construction method, aiming to achieve an effective combination of a prestressed support and a pressure-yielding support and improve the stability of the support structure.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a tunnel prestressed adaptive pressure-yielding steel frame and a construction method, including a support frame body and an adaptive structure, the support frame body is divided into multiple sections, and two adjacent sections of the support frame body are connected by means of an adaptive structure; the adaptive structure includes a prestressed device and a pressure-yielding device connected in sequence, the prestressed device includes a prestressed tensioning structure with a tendency to expand and contract along its length direction; the pressure-yielding device includes a pressure-yielding support structure with a tendency to bend along its length direction; the prestress of the prestressed tensioning structure is less than the pressure-yielding starting force of the pressure-yielding support structure.

[0005] As another embodiment of the present application, the prestressed tensioning structure includes a first positioning plate, a second positioning plate and a telescopic member, the two ends of the telescopic member along the telescopic direction are respectively connected to the first positioning plate and the second positioning plate, and the telescopic member is respectively connected to the support frame body and the pressure-releasing device by means of the first positioning plate and the second positioning plate; the telescopic member is always in a contracted state during assembly and construction with the support frame body; the telescopic member is one or more, and when the telescopic member is multiple, the multiple telescopic members are evenly distributed between the two positioning plates.

[0006] As another embodiment of the present application, the pressure-yielding support structure includes a first pressure-bearing plate, a second pressure-bearing plate and a pressure-yielding element; the two force-bearing ends of the pressure-yielding element are respectively connected to the first pressure-bearing plate and the second pressure-bearing plate, and the pressure-yielding element is respectively connected to the pressure-yielding device and the next section of the support frame body by means of the first pressure-bearing plate and the second pressure-bearing plate.

[0007] As another embodiment of the present application, the pressure-releasing element includes two symmetrically arranged concave pressure-releasing plates; a pressure-releasing space is formed between the first pressure-bearing plate and the second pressure-bearing plate, and the concave pressure-releasing plates are located at the edge of the pressure-releasing space and convexly deform toward the center of the pressure-releasing space under pressure.

[0008] As another embodiment of the present application, a pair of flexures are provided between the two concave pressure plates, and both flexures are arc-shaped plates; the open ends of the two flexures are respectively facing the first pressure plate and the second pressure plate, and the closed ends of the two flexures are in contact with each other.

[0009] As another embodiment of the present application, a support plate with a semicircular cross-section is provided on the inner side of the flexure.

[0010] As another embodiment of the present application, the pressure-releasing element is a metal block, and the metal block is provided with a plurality of rows of relief holes along the length direction, and the diameter of the relief holes gradually decreases or increases from the first pressure plate to the second pressure plate.

[0011] As another embodiment of the present application, the prestressed device and the pressure-releasing device both include a retractable outer shell, the retractable outer shell includes two flange mounting plates and a sleeve structure, the sleeve structure includes an inner cylinder and an outer cylinder, the outer cylinder is sleeved on the outside of the inner cylinder and slides along the length direction of the inner cylinder; the inner cavity of the retractable outer shell is used to accommodate the prestressed release structure or the pressure-releasing support structure.

[0012] The beneficial effects of the tunnel prestressed adaptive pressure-yielding steel frame provided by the present invention are as follows: compared with the prior art, the tunnel prestressed adaptive pressure-yielding steel frame of the present invention adds a prestressed release structure and a pressure-yielding support structure between two adjacent sections of the support frame body, utilizes the release of the prestressed release structure to apply a supporting force to the surrounding rock, and forms an active supporting force; utilizes the compression deformation of the pressure-yielding support structure and the shrinkage of the prestressed release structure to bear the surrounding rock pressure; realizes the effective combination of the prestressed device and the pressure-yielding device, and improves the stability of the support structure; in addition, the prestress of the prestressed release structure will not drive the pressure-yielding support structure to deform.

[0013] A construction method of a tunnel prestressed adaptive pressure-yielding steel frame is also provided, which adopts the above-mentioned tunnel prestressed adaptive pressure-yielding steel frame and comprises the following steps:

[0014] S1. Tunnel excavation, installation of support frame, prestressing device and pressure relief device to form a support ring;

[0015] S2, prestressed release structure, the diameter of the support ring is extended outward, and the support ring actively applies support force to the surrounding rock to form active support force;

[0016] S3. When the surrounding rock pressure is greater than the main force, the prestressed tensioning structure is loaded and begins to compress and deform. As the surrounding rock squeezes and deforms toward the excavation contour surface, the diameter of the tunnel steel frame ring decreases;

[0017] S4. When the surrounding rock pressure is greater than the initial pressure of the pressure-releasing device, the pressure-releasing device starts to compress and deform;

[0018] S5. The prestressing device and the pressure-releasing device continue to compress and deform together until the surrounding rock pressure and the support force reach a force balance, so that the support ring achieves a stable state.

[0019] As another embodiment of the present application, the initial pressure-releasing force of the pressure-releasing device is greater than the tunnel relaxation load and less than the supporting bearing capacity of the steel frame itself; the maximum pressure-releasing force of the pressure-releasing device is less than the supporting bearing capacity of the steel frame itself.

[0020] The beneficial effects of the tunnel prestressed adaptive pressure-yielding steel frame construction method provided by the present invention are: compared with the prior art, the tunnel prestressed adaptive pressure-yielding steel frame construction method of the present invention adopts the above-mentioned tunnel prestressed adaptive pressure-yielding steel frame, and has all the beneficial effects thereof; by installing a support ring in the tunnel, through the synergistic effect of the prestressed device and the pressure-yielding device, active support force is applied to the surrounding rock with pre-stress, and pressure-yielding energy is released by the joint compression deformation of the steel frame prestressed device and the adaptive pressure-yielding device, so that the surrounding rock energy can be continuously released until the surrounding rock pressure and the support force are balanced, so that the support structure achieves a stable state. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a tunnel prestressed adaptive yielding steel frame provided in an embodiment of the present invention;

[0023] Figure 2 A schematic structural diagram of a prestressed release structure provided in an embodiment of the present invention;

[0024] Figure 3 A schematic structural diagram of a pressure-yielding support structure provided in a first embodiment of the present invention;

[0025] Figure 4 A schematic structural diagram of a pressure-yielding support structure provided in a second embodiment of the present invention;

[0026] Figure 5 A schematic diagram of the structure of a retractable housing provided by an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of the stress state of the support ring provided by an embodiment of the present invention in an active support state;

[0028] Figure 7 A schematic diagram of the stress state of the support ring provided in an embodiment of the present invention in a pressure-yielding support state.

[0029] In the figure: 1. support frame; 2. prestressing device; 3. pressure-relieving device; 4. flange mounting plate; 5. inner cylinder; 6. outer cylinder; 7. hydraulic jack; 8. mechanical jack; 9. first positioning plate; 10. second positioning plate; 11. first pressure-bearing plate; 12. second pressure-bearing plate; 13. metal block; 14. relief hole; 15. concave pressure-relieving plate; 16. arc plate; 17. support plate. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] See also Figures 1 to 7 , the tunnel prestressed adaptive pressure-yielding steel frame and construction method provided by the present invention are now described. The tunnel prestressed adaptive pressure-yielding steel frame includes a support frame body 1 and an adaptive structure. The support frame body 1 is multi-section, and two adjacent sections of the support frame body 1 are connected by means of the adaptive structure; the adaptive structure includes a prestressed device 2 and a pressure-yielding device 3 connected in sequence, the prestressed device 2 includes a prestressed tensioning structure having a tendency to stretch along its length direction; the pressure-yielding device 3 includes a pressure-yielding support structure having a tendency to buckle along its length direction; the prestress of the prestressed tensioning structure is less than the pressure-yielding starting force of the pressure-yielding support structure.

[0032] Compared with the prior art, the tunnel prestressed adaptive yielding steel frame provided by the present invention adds a prestressed release structure and a yielding support structure between two adjacent sections of the support frame body 1, utilizes the release of the prestressed release structure to apply a supporting force to the surrounding rock, and forms an active supporting force; utilizes the compression deformation of the yielding support structure and the retraction of the prestressed release structure to bear the surrounding rock pressure; realizes the effective combination of the prestressed device 2 and the yielding device 3, and improves the stability of the support structure; in addition, the prestress of the prestressed release structure will not drive the yielding support structure to deform.

[0033] Specifically, the support frame body 1 is a single-layer support structure or a multi-layer support structure. The support frame body 1 can be made of I-beam, H-beam or a combination of the two. Steel plate flange bolts or welding can be used to connect or fix between the support frame body 1 and the prestressing device 2, between the prestressing device 2 and the pressure-releasing device 3, and between the pressure-releasing device 3 and the support frame body 1.

[0034] The multi-section support frame body 1 and the prestressing device 2 and the pressure-releasing device 3 cooperate to form a support ring. The installation order of the prestressing device 2 and the pressure-releasing device 3 installed in the gap between two adjacent sections of the support frame body 1 is adjustable.

[0035] like Figure 1 As shown, the support ring includes four sections of support frame bodies 1 and four adapting structures, and the four adapting structures are evenly distributed in the support ring. The prestressing device 2 and the pressure-releasing device 3 of the adapting structure are distributed clockwise or counterclockwise.

[0036] In some possible embodiments, see Figure 2 The prestressed tensioning structure includes a first positioning plate 9, a second positioning plate 10 and a telescopic member. The two ends of the telescopic member along the telescopic direction are respectively connected to the first positioning plate 9 and the second positioning plate 10. The telescopic member is connected to the support frame body 1 and the pressure-releasing device 3 respectively by means of the first positioning plate 9 and the second positioning plate 10; the telescopic member is always in a contracted state when assembled with the support frame body 1; there are one or more telescopic members. When there are multiple telescopic members, the multiple telescopic members are evenly distributed between the two positioning plates.

[0037] The first positioning plate 9 and the second positioning plate 10 face the support frame body 1 and the pressure-releasing device 3 respectively, the first positioning plate 9 is connected to the support frame body 1, and the second positioning plate 10 is connected to the pressure-releasing device 3. The telescopic member is located between the first positioning plate 9 and the second positioning plate 10, and the telescopic member is telescopic along its own length direction to drive the first positioning plate 9 and the second positioning plate 10 to move closer or farther away.

[0038] When the telescopic member extends along its own length direction, it drives the first positioning plate 9 and the second positioning plate 10 to move away from each other, thereby expanding the support ring and applying pressure to the surrounding rock by the support ring.

[0039] When the force applied by the surrounding rock is greater than the pre-stress of the telescopic member, the telescopic member contracts under the pressure of the surrounding rock, driving the first positioning plate 9 and the second positioning plate 10 closer, so that the support ring retracts and the inner diameter of the support ring decreases; at the same time, the pressure relief effect on the surrounding rock is achieved.

[0040] A clearance space for installing the telescopic member is formed between the first positioning plate 9 and the second positioning plate 10. The number of telescopic members located in the clearance space may be one or more. In order to avoid the problem of sudden loss of supporting force when using one telescopic member, multiple telescopic members are often used for simultaneous support in actual construction.

[0041] like Figure 3 As shown, multiple telescopic parts may include pneumatic jacks, hydraulic jacks 7 and mechanical jacks 8. During construction, a pneumatic jack or hydraulic jack 7 is installed in the middle of the make way space, and a mechanical jack 8 is installed on both sides thereof. Active support force is provided by the combination of pneumatic / hydraulic jacks 7 and mechanical jacks 8, thereby avoiding the problem of sudden loss of active support force due to pressure failure caused by using a single jack. For example, the telescopic part includes a hydraulic jack 7 and mechanical jacks 8 located on both sides of the hydraulic jack 7. The positioning plates may be one group or multiple groups, and multiple telescopic parts may be installed on the same group of positioning plates, or each telescopic part may be provided with a group of positioning plates.

[0042] In addition, the telescopic member can also adopt a pre-stressed spring structure, which is pre-stressed during construction and installation to keep it in a compressed state. After the construction of the support ring is completed, it is released. The released spring applies force to the support ring and drives the support ring to expand outward, thereby squeezing the surrounding rock.

[0043] For easy installation, the prestressed device 2 also includes a telescopic shell, which includes two flange mounting plates 4 and a sleeve structure, which includes an inner tube 5 and an outer tube 6 that are sleeved and connected, and the outer tube 6 slides along the length direction of the inner tube 5; the inner cavity of the telescopic shell is used to accommodate the prestressed tensioning structure. Figure 5 shown.

[0044] The prestressed tensioning structure is located in the inner cavity of the telescopic shell, and the first positioning plate 9 and the second positioning plate 10 are respectively connected to the two flange mounting plates 4; bolt holes are provided on the two flange mounting plates 4, and the two flange mounting plates 4 are respectively connected to the ends of the support frame 1 and the pressure-releasing device 3 by bolts or welding.

[0045] In some possible embodiments, see Figure 3 and Figure 4 The pressure-releasing support structure includes a first pressure-bearing plate 11, a second pressure-bearing plate 12 and a pressure-releasing element; the two force-bearing ends of the pressure-releasing element are respectively connected to the first pressure-bearing plate 11 and the second pressure-bearing plate 12, and the pressure-releasing element is respectively connected to the pressure-releasing device 3 and the next section of the support frame 1 by means of the first pressure-bearing plate 11 and the second pressure-bearing plate 12.

[0046] The first pressure plate 11 and the second pressure plate 12 are arranged in parallel and spaced apart, and a pressure relief space is formed between the first pressure plate 11 and the second pressure plate 12, and a pressure relief element is installed in the pressure relief space. The two ends of the pressure relief element are respectively connected to the first pressure plate 11 and the second pressure plate 12, and the pressure relief element has a deformation tendency along a direction perpendicular to the connecting line of the first pressure plate 11 and the second pressure plate 12. When the pressure relief element is squeezed by the first pressure plate 11 and the second pressure plate 12, the pressure relief element is compressed and deformed, and it is deformed along a direction perpendicular to the connecting line of the first pressure plate 11 and the second pressure plate 12, so as to satisfy the displacement of the first pressure plate 11 and the second pressure plate 12 while applying pressure to the first pressure plate 11 and the second pressure plate 12, thereby maintaining the force stability of the support ring.

[0047] like Figure 3 As shown, the pressure-releasing element includes two symmetrically arranged concave pressure-releasing plates 15, and a pressure-releasing space is formed between the first pressure-bearing plate 11 and the second pressure-bearing plate 12. The concave pressure-releasing plate 15 is located at the edge of the pressure-releasing space and bulges toward the center of the pressure-releasing space when under pressure.

[0048] The two ends of the concave yield plate 15 in the length direction are respectively connected to the first pressure plate 11 and the second pressure plate 12. The two concave yield plates are symmetrically arranged at the two edges of the yield space, and the protruding direction of the concave yield plates is toward the space between the two concave yield plates. Under the extrusion force of the first pressure plate 11 and the second pressure plate 12, the middle part of the concave yield plate is deformed toward the middle part of the yield space. As the deformation of the concave yield plate increases, the distance between the first pressure plate 11 and the second pressure plate 12 decreases.

[0049] Optionally, the concave portion allows the thickness of the pressing plate 15 to gradually decrease from both ends toward the middle.

[0050] A pair of buckling pieces are provided between the two concave pressure plates 15, and both buckling pieces are arc-shaped plates 16; the open ends of the two buckling pieces face the first pressure plate 11 and the second pressure plate 12 respectively, and the closed ends of the two buckling pieces fit together.

[0051] The two bending members are located in the pressure relief space between the two concave pressure relief plates 15. The two bending members are arc plates 16 arranged in opposite directions, namely a first arc plate and a second arc plate, the opening of the first arc plate faces the first pressure plate 11, and both ends of the first arc plate are connected to the first pressure plate 11. On the contrary, the opening of the second arc plate faces the second pressure plate 12, and both ends of the second arc plate are connected to the second pressure plate 12. The middle parts of the first arc plate and the second arc plate extend toward the middle part of the pressure relief space. The middle parts of the first arc plate and the second arc plate are abutted or welded to fix. Optionally, the structures of the first arc plate and the second arc plate are consistent, and the thickness of the first arc plate and the second arc plate gradually decreases from both ends to the middle part.

[0052] In addition, a support plate 17 with a semicircular cross section is provided on the inner side of the flexure. The two semicircular support plates 17 are located on the inner sides of the first curved plate and the second curved plate respectively. The two support plates 17 are the first support plate and the second support plate respectively, and the first support plate is correspondingly arranged in the inner cavity surrounded by the first curved plate and the first pressure-bearing plate 11; the second straight plate is correspondingly arranged in the inner cavity surrounded by the second curved plate and the second pressure-bearing plate 12.

[0053] Taking the first support plate as an example, the first support plate is an arc-shaped plate 16 with a semicircular cross section, the open end of the arc-shaped plate 16 faces one side of the first supporting plate, and both ends are connected to the first supporting plate. The arc-shaped plate 16 protrudes toward the middle of the pressure relief space, and a gap is left between the middle of the first support plate and the middle of the first arc-shaped plate.

[0054] The second support plate has the same structure as the first support plate, and the second support plate is symmetrically arranged with the first support plate.

[0055] When the first curved plate and the second curved plate are squeezed and deformed until their middle parts fit with the first support plate and the second support plate, the first support plate and the second support plate support the first curved plate and the second curved plate, thereby improving the support stability.

[0056] like Figure 4 As shown, the pressure-releasing element is a metal block 13, and the metal block 13 is provided with a plurality of rows of relief holes 14 along the length direction, and the diameter of the relief holes 14 gradually decreases or increases from the first pressure-bearing plate 11 to the second pressure-bearing plate 12. The metal block 13 is connected to the first pressure-bearing plate 11 and the second pressure-bearing plate 12 by welding or bolts.

[0057] For easy installation, the pressure-releasing device 3 includes a retractable housing, which includes two flange mounting plates 4 and a sleeve structure, which includes an inner sleeve 5 and an outer sleeve 6. The outer sleeve 6 is sleeved on the outer side of the inner sleeve 5 and slides along the length direction of the inner sleeve 5. The inner cavity of the retractable housing is used to accommodate the pressure-releasing support structure. Figure 5 shown.

[0058] The yield support structure is located in the inner cavity of the telescopic shell, and the first pressure plate 11 and the second pressure plate 12 are respectively connected to the two flange mounting plates 4; bolt holes are provided on the two flange mounting plates 4, and the two flange mounting plates 4 are respectively connected to the prestressed device 2 and the support frame body 1 by bolts or welding.

[0059] A construction method of a tunnel prestressed adaptive pressure-yielding steel frame is also provided, which adopts the above-mentioned tunnel prestressed adaptive pressure-yielding steel frame and comprises the following steps:

[0060] S1, tunnel excavation, installation of support frame 1, prestressing device 2 and pressure relief device 3 to form a support ring;

[0061] S2, prestressed release structure, the diameter of the support ring is extended outward, and the support ring actively applies support force to the surrounding rock to form active support force;

[0062] S3. When the surrounding rock pressure is greater than the active support force, the prestressed tensioning structure is loaded and begins to compress and deform. As the surrounding rock squeezes and deforms toward the excavation contour surface, the diameter of the tunnel steel frame ring decreases;

[0063] S4, when the surrounding rock pressure is greater than the starting force of the pressure-releasing device 3, the pressure-releasing device 3 starts to compress and deform;

[0064] S5. The prestressing device 2 and the pressure-releasing device 3 continue to compress and deform together until the surrounding rock pressure and the supporting force reach a force balance, so that the supporting ring achieves a stable state.

[0065] Compared with the prior art, the tunnel prestressed adaptive pressure-yielding steel frame construction method provided by the present invention adopts the above-mentioned tunnel prestressed adaptive pressure-yielding steel frame and has all the beneficial effects thereof; by installing a support ring in the tunnel, the prestressed device 2 and the pressure-yielding device 3 work together to apply active support force to the surrounding rock with prestress, and the pressure-yielding energy release is achieved by the joint compression deformation of the steel frame prestressed device 2 and the adaptive pressure-yielding device 3, so that the surrounding rock energy can be continuously released until the surrounding rock pressure and the support force are balanced, so that the support structure achieves a stable state.

[0066] Specifically, in step S1, the outer wall of the support ring is attached to the excavation contour surface; during installation, the prestressing device 2 is always in a compressed state. According to the tunnel construction method, the excavation operation is continuously completed, and the support frame 1, the prestressing device 2 and the pressure relief device 3 are installed in time; the support ring is arranged on the inner side of the excavation contour surface.

[0067] After completing the construction and installation of the support ring, proceed to step S2. In step S2, the prestressed device 2 is released. Under the extension of the prestressed release structure, the outer diameter of the support ring is driven to expand outward, and the support ring actively applies a supporting force to the surrounding rock to form an active support force.

[0068] The surrounding rock continues to squeeze and deform toward the excavation contour surface, and the surrounding rock pressure on the support continues to increase. In step S3, when the surrounding rock pressure is greater than the active support force, the prestressed tensioning structure is loaded and begins to compress and deform. As the surrounding rock squeezes and deforms toward the excavation contour surface, the diameter of the support ring decreases, and the support ring begins to deform and yield to the pressure.

[0069] In step S4, as the surrounding rock is further squeezed, the surrounding rock pressure on the support structure continues to increase. When the surrounding rock pressure is greater than the starting force of the pressure-releasing device 3, the pressure-releasing device 3 begins to compress and deform. Under the joint compression and deformation of the prestressing device 2 and the pressure-releasing device 3, the surrounding rock is squeezed and deformed toward the excavation contour surface, and the diameter of the tunnel steel frame ring continues to decrease. The surrounding rock continues to squeeze and deform toward the excavation contour surface to release energy, reducing the pressure of the surrounding rock on the support structure.

[0070] In step S5, under the continuous joint compression deformation of the prestressing device 2 and the pressure-releasing device 3, the support structure continues to release pressure and the surrounding rock energy continues to be released until the surrounding rock pressure and the supporting force reach a force balance, so that the support structure achieves a stable state.

[0071] The prestressing device 2 and the pressure-yielding device 3 cooperate with the deformation and stress of the surrounding rock, and their cooperation relationship includes: the prestress of the prestressing device 2 is less than the pressure-yielding starting force of the pressure-yielding device 3; the expansion and contraction deformation of the steel frame prestressing device 2 and the pressure-yielding deformation of the pressure-yielding device 3 and the pressure-yielding deformation of the surrounding rock.

[0072] Prestressed adaptive yielding steel frame for soft rock large deformation tunnel, stress coordination: the prestress of prestressing device 2 should be less than the yielding starting force of yielding device 3; the yielding starting force of yielding device 3 should be greater than the tunnel relaxation load and less than the supporting bearing capacity of the steel frame itself. The maximum yielding pressure of yielding device 3 should be less than the supporting bearing capacity of the steel frame itself, and the yielding pressure of yielding device 3 should be between the yielding starting force and the maximum yielding pressure.

[0073] Coordination of deformation of tunnel prestressed adaptive yielding steel frame: contraction deformation of prestressed device 2 + yielding deformation of yielding device 3 are coordinated with yielding deformation of surrounding rock to meet the stability requirements of support structure.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. The tunnel prestressed adaptive yielding steel frame is characterized by: The invention comprises a support frame body (1) and an adaptable structure, wherein the support frame body (1) is composed of multiple sections, and two adjacent sections of the support frame body (1) are connected by means of the adaptable structure; the adaptable structure comprises a prestressing device (2) and a pressure-releasing device (3) connected in sequence, wherein the prestressing device (2) comprises a prestressing release structure having a tendency to expand and contract along its length direction; the pressure-releasing device (3) comprises a pressure-releasing support structure having a tendency to bend along its length direction; the prestress of the prestressing release structure is less than the pressure-releasing starting force of the pressure-releasing support structure; The prestressed release structure comprises a first positioning plate (9), a second positioning plate (10) and a telescopic member, wherein the two ends of the telescopic member along the telescopic direction are respectively connected to the first positioning plate (9) and the second positioning plate (10), and the telescopic member is respectively connected to the support frame body (1) and the pressure-releasing device (3) by means of the first positioning plate (9) and the second positioning plate (10); the telescopic member is always in a contracted state when assembled with the support frame body (1); the telescopic member is one or more, and when the telescopic member is multiple, the multiple telescopic members are evenly distributed between the two positioning plates.

2. The tunnel prestressed adaptive yielding steel frame according to claim 1, characterized in that: The pressure-releasing support structure comprises a first pressure-bearing plate (11), a second pressure-bearing plate (12) and a pressure-releasing element; the two force-bearing ends of the pressure-releasing element are respectively connected to the first pressure-bearing plate (11) and the second pressure-bearing plate (12); the pressure-releasing element is respectively connected to the pressure-releasing device (3) and the next section of the support frame (1) by means of the first pressure-bearing plate (11) and the second pressure-bearing plate (12).

3. The tunnel prestressed adaptive yielding steel frame according to claim 2, characterized in that: The pressure-releasing element comprises two symmetrically arranged concave pressure-releasing plates (15); a pressure-releasing space is formed between the first pressure-bearing plate (11) and the second pressure-bearing plate (12); the concave pressure-releasing plate (15) is located at the edge of the pressure-releasing space and convexly deforms toward the center of the pressure-releasing space when under pressure.

4. The tunnel prestressed adaptive yielding steel frame according to claim 3, characterized in that: A pair of flexures are provided between the two inwardly concave pressure plates (15), and both flexures are arc-shaped plates (16); the open ends of the two flexures face the first pressure-bearing plate (11) and the second pressure-bearing plate (12), respectively, and the closed ends of the two flexures fit together.

5. The tunnel prestressed adaptive yielding steel frame according to claim 4, characterized in that: The inner side of each of the flexures is provided with a support plate (17) with a semicircular cross section.

6. The tunnel prestressed adaptive yielding steel frame according to claim 2, characterized in that: The pressure-releasing element is a metal block (13), and the metal block (13) is provided with a plurality of rows of relief holes (14) along the length direction, and the diameter of the relief holes (14) gradually decreases or increases from the first pressure-bearing plate (11) to the second pressure-bearing plate (12).

7. The tunnel prestressed adaptive yielding steel frame according to claim 1, characterized in that: The prestressed device (2) and the pressure-releasing device (3) both comprise a telescopic outer shell, the telescopic outer shell comprising two flange mounting plates (4) and a sleeve structure, the sleeve structure comprising an inner cylinder (5) and an outer cylinder (6), the outer cylinder (6) being sleeved on the outer side of the inner cylinder (5) and sliding along the length direction of the inner cylinder (5); the inner cavity of the telescopic outer shell is used to accommodate the prestressed release structure or the pressure-releasing support structure.

8. The construction method of tunnel prestressed adaptive yielding steel frame is characterized by: The tunnel prestressed adaptive yielding steel frame according to any one of claims 1 to 7 is adopted, comprising the following steps: S1, tunnel excavation, installation of a support frame body (1), a prestressing device (2) and a pressure relief device (3) to form a support ring; S2, prestressed release structure, the diameter of the support ring is extended outward, and the support ring actively applies support force to the surrounding rock to form active support force; S3. When the surrounding rock pressure is greater than the main force, the prestressed tensioning structure is loaded and begins to compress and deform. As the surrounding rock squeezes and deforms toward the excavation contour surface, the diameter of the tunnel steel frame ring decreases; S4. When the surrounding rock pressure is greater than the starting pressure of the pressure-releasing device (3), the pressure-releasing device (3) starts to compress and deform; S5. The prestressing device (2) and the pressure-releasing device (3) continue to compress and deform together until the surrounding rock pressure and the supporting force reach a force balance, so that the supporting ring achieves a stable state.

9. The construction method of the tunnel prestressed adaptive yielding steel frame according to claim 8, characterized in that: The initial pressure release force of the pressure release device (3) is greater than the tunnel relaxation load and less than the supporting bearing capacity of the steel frame itself; the maximum pressure release force of the pressure release device (3) is less than the supporting bearing capacity of the steel frame itself.

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