Interlocking tunnel pressure-yielding support structure and construction method

Abstract

The present invention provides an interlocking tunnel pressure-yielding support structure and a construction method, which belongs to the technical field of tunnel construction, wherein the interlocking tunnel pressure-yielding support structure includes a radial pressure-yielding support structure and an annular pressure-yielding support structure; the radial pressure-yielding support structure includes a concrete buffer layer and a radial support assembly; the concrete buffer layer covers the surface of the surrounding rock; the support assembly includes a prestressed anchor rod and a support shell embedded in the concrete buffer layer, the support shell is an arc-shaped structure with an opening toward one side of the surrounding rock, the prestressed anchor rod is connected to the support shell and fixed in the surrounding rock; the annular pressure-yielding support structure includes a multi-section support frame, a plurality of prestressed tensioning structures and a plurality of pressure-yielding support structures, and the annular pressure-yielding support structure is arranged to form a support ring. The interlocking tunnel pressure-yielding support structure provided by the present invention ensures the stability and safety of the radial and annular pressure-yielding support structures through joint pressure-yielding and cooperative deformation in the radial and annular directions, thereby improving the stability of the support structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel construction, and more specifically, relates to an interlocking tunnel pressure-yielding support structure and a construction method. Background Art

[0002] The surrounding rock and support stability of high-in-situ stress soft rock large deformation tunnels have become major engineering problems faced by tunnel construction. The tunnel collapse and support cracking caused by the large deformation, fast deformation rate and long deformation duration of the surrounding rock of soft rock large deformation tunnels have become one of the main problems affecting the safety of tunnel construction and operation. Tunnel yielding support measures have become a generally accepted support measure for tunnel construction, but under extremely high in-situ stress, the tunnel deformation is large, and a single yielding measure is difficult to meet the needs of tunnel construction. Summary of the invention

[0003] The object of the present invention is to provide an interlocking tunnel pressure-yielding support structure and a construction method, aiming to realize radial and circumferential combined pressure-yielding active bearing support for soft rock large deformation tunnels.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide an interlocking tunnel pressure-yielding support structure, including a radial pressure-yielding support structure and an annular pressure-yielding support structure;

[0005] The radial yield support structure includes a concrete buffer layer and a radial support assembly; the concrete buffer layer covers the surface of the surrounding rock; the support assembly includes a prestressed anchor rod and a support shell embedded in the concrete buffer layer, the support shell is an arc-shaped structure with an opening toward one side of the surrounding rock, and the prestressed anchor rod is connected to the support shell and fixed in the surrounding rock;

[0006] The annular pressure-yielding support structure includes multiple support frames, a plurality of prestressed release structures and a plurality of pressure-yielding support structures. The annular pressure-yielding support structure is arranged to form a support ring, and both the prestressed release structure and the pressure-yielding support structure have a degree of freedom along the tangent direction of the support ring.

[0007] As another embodiment of the present application, the concrete buffer layer includes a primary concrete buffer layer and a secondary concrete buffer layer sprayed sequentially along the thickness direction, the primary concrete buffer layer is sprayed on the surface of the surrounding rock, the primary concrete buffer layer includes a first concrete buffer layer and a second concrete buffer layer, the prestressed anchor rod and the support shell are installed on the outside of the first concrete buffer layer, the second concrete buffer layer is sprayed on the outside of the first concrete buffer layer, and is embedded with the support shell and the annular yield support structure; the secondary concrete buffer layer is sprayed on the outside of the second concrete buffer layer and the support shell, the secondary concrete buffer layer solidifies, and the support shell and the prestressed anchor rod are enclosed in the concrete buffer layer.

[0008] As another embodiment of the present application, the support shell includes an outer curved plate, an inner curved plate and a pressure-yielding filling layer, the inner curved plate is located on the side close to the surrounding rock, the inner curved plate and the outer curved plate are arranged in parallel, an interlayer space is formed between the inner curved plate and the outer curved plate, the pressure-yielding filling layer is located in the interlayer space, and the pressure-yielding filling layer has the freedom to bend along the thickness direction.

[0009] As another embodiment of the present application, the support shell is a hemispherical structure; the end face of the open end of the support shell is in contact with the surrounding rock at the top of the tunnel, and the closed end of the support shell faces downward; the outer arc plate and the inner arc plate have a sealing end plate on the side facing the open end, and the sealing end plate is used to close the interlayer space; the edge of the sealing end plate close to the outer arc plate has an outer edge protrusion protruding outward, and the outer edge protrusion is in contact with the surrounding rock wall.

[0010] As another embodiment of the present application, the cross-sectional direction of the support shell is set at an angle with the length direction of the tunnel, and the two cross-connected support shells form a cross-beam structure; the mezzanine spaces in the two support shells are connected, and the prestressed anchor rods in the mezzanine space vertically penetrate the center of the connection between the two support shells; vertical end plates are provided around the sides of the support shells, and the vertical end plates are concave toward the mezzanine space.

[0011] 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 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 support structure by means of the first positioning plate and the second positioning plate; the telescopic member is always in a retracted 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.

[0012] 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 support structure and the next section of the support frame body by means of the first pressure-bearing plate and the second pressure-bearing plate.

[0013] As another embodiment of the present application, the pressure-releasing element comprises two symmetrically arranged inwardly concave pressure-releasing plates; a pressure-releasing space is formed between the first pressure-bearing plate and the second pressure-bearing plate, and the inwardly concave pressure-releasing plate is located at the edge of the pressure-releasing space and convexly deforms toward the center of the pressure-releasing space under pressure;

[0014] A pair of flexures are provided between the two inwardly concave pressure plates, and both flexures are arc-shaped plates; the open ends of the two flexures face the first pressure plate and the second pressure plate respectively, and the closed ends of the two flexures fit together.

[0015] 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.

[0016] The beneficial effects of the interlocking tunnel pressure-yielding support structure provided by the present invention are as follows: compared with the prior art, the interlocking tunnel pressure-yielding support structure of the present invention has an annular pressure-yielding support structure and a radial pressure-yielding support structure in the support ring; the prestressed tensioning structure and the pressure-yielding support structure of the annular pressure-yielding support structure respectively cooperate to realize the annular prestressed tensioning and pressure-yielding retraction of the support ring; the prestressed anchor rods and the support shell of the radial pressure-yielding support respectively cooperate to realize the radial prestressed tensioning and pressure-yielding retraction of the support ring; when the tunnel is deformed, the radial and annular pressure-yielding support structures are ensured to be stable and safe through the combined pressure-yielding deformation in the radial and annular directions, and the pressure-yielding limit state is entered synchronously, thereby improving the stability of the support structure; the problem that the existing single pressure-yielding measure cannot meet the support measures for soft rock tunnels with large deformation is solved.

[0017] A construction method of an interlocking tunnel pressure-yielding support structure is also provided, which is characterized in that the above-mentioned interlocking tunnel pressure-yielding support structure is adopted and comprises the following steps:

[0018] S1, excavation of the upper step of the tunnel, spraying of the first layer of radial yield concrete on the excavation contour surface;

[0019] S2. Install prestressed anchor rods and support shells on the first layer of radial yield concrete surface, and apply prestress to the anchor rods; at the same time, install the support frame, apply the locking anchor rods, and assemble the prestressed tensioning structure and yield support structure;

[0020] S3, spraying the second layer of radial yield concrete, embedding the support shell and the support frame into the second layer of radial yield concrete, forming a steel frame embedded structure;

[0021] S4, excavating the lower step of the tunnel, repeating the installation of the support frame, the prestressed tensioning structure and the pressure-releasing support structure in steps S1 and S2 for the lower step excavation contour surface;

[0022] S5, let the compression support structure form a ring, release the prestressed release structure, so that the compression support structure is squeezed and deformed toward the surrounding rock, and the diameter of the compression support structure is extended to form an active support force;

[0023] S6, spraying a secondary concrete buffer layer to form an integral support structure;

[0024] S7. The surrounding rock continues to squeeze and deform toward the excavation contour surface. When the surrounding rock pressure is greater than the main force, the prestressed tensioning structure bears the load and begins to compress and deform. As the surrounding rock squeezes and deforms toward the excavation contour surface, the diameter of the compression support structure is reduced. At the same time, the prestressed anchor rods bear the load and compress and deform.

[0025] S8. The surrounding rock continues to be squeezed and deformed toward the excavation contour surface, and the surrounding rock pressure on the support continues to increase. When the surrounding rock pressure is greater than the yielding starting force of the yielding support structure, the yielding support structure begins to compress and deform; at the same time, the support shell is compressed and deformed; the annular yielding support structure and the radial yielding support structure deform in coordination until the surrounding rock pressure and the support force reach a force balance.

[0026] The beneficial effects of the interlocking tunnel pressure-yielding support structure construction method provided by the present invention are: compared with the prior art, the interlocking tunnel pressure-yielding support structure construction method of the present invention adopts the above-mentioned interlocking tunnel pressure-yielding support structure, and has all the beneficial effects thereof; when the tunnel is deformed, the radial and circumferential joint pressure-yielding coordinated deformation is achieved to ensure the stability and safety of the radial and circumferential pressure-yielding support structures, and the pressure-yielding limit state is entered synchronously, thereby improving the stability of the support structure; and the problem that the existing single pressure-yielding measure cannot meet the support measures for soft rock tunnels with large deformation is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] Figure 1 A schematic structural diagram of an interlocking tunnel pressure-yielding support structure provided in an embodiment of the present invention;

[0029] Figure 2An enlarged schematic cross-sectional view of an interlocking tunnel pressure-yielding support structure provided in an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the structure of a prestressed anchor rod provided in an embodiment of the present invention;

[0031] Figure 4 A cross-sectional view of a prestressed anchor rod provided by an embodiment of the present invention;

[0032] Figure 5 A schematic structural diagram of a first type of support shell provided in an embodiment of the present invention;

[0033] Figure 6 A schematic structural diagram of a second type of support shell provided in an embodiment of the present invention;

[0034] Figure 7 A schematic structural diagram of a first prestressed release structure provided in an embodiment of the present invention;

[0035] Figure 8 A schematic structural diagram of a second prestressed release structure provided in an embodiment of the present invention;

[0036] Fig. 9 A schematic structural diagram of a first type of pressure-yielding support structure provided in an embodiment of the present invention;

[0037] Fig.10 A structural schematic diagram of a second pressure-yielding support structure provided in an embodiment of the present invention;

[0038] Fig.11 A schematic diagram of the structure of a retractable housing provided by an embodiment of the present invention;

[0039] Fig.12 A schematic diagram of the stress state of the support ring provided by an embodiment of the present invention in an active support state;

[0040] Fig.13 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.

[0041] In the figure: 100, support frame; 200, prestressed anchor rod; 201, lower segment; 202, middle segment; 203, upper segment; 204, pressure-releasing member; 205, pre-compressed disc spring; 300, support shell; 301, outer arc plate; 302, inner arc plate; 303, pressure-releasing filling layer; 304, sealing end plate; 400, anchor expansion sleeve; 500, prestressed tensioning structure; 501, mechanical jack; 502, hydraulic jack; 503, first positioning plate; 504, second positioning plate; 505, pre-compressed spring structure; 506, Grouting hole; 507, vertical side plate; 508, fixed plate; 600, yield support structure; 601, concave yield plate; 602, first pressure-bearing plate; 603, second pressure-bearing plate; 604, arc-shaped plate body; 605, support plate; 606, metal block; 607, yield hole; 700, sleeve structure; 701, inner tube; 702, outer tube; 703, flange mounting plate; 800, first concrete buffer layer; 801, secondary concrete buffer layer; 802, second concrete buffer layer; 803, surrounding rock; 804, primary sprayed concrete layer; 805, steel mesh. DETAILED DESCRIPTION

[0042] 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.

[0043] See also Figures 1 to 13 , the interlocking tunnel pressure-yielding support structure and construction method provided by the present invention are now described. The interlocking tunnel pressure-yielding support structure includes a radial pressure-yielding support structure and an annular pressure-yielding support structure; the radial pressure-yielding support structure includes a concrete buffer layer and a radial support assembly; the concrete buffer layer covers the surface of the surrounding rock 803; the support assembly includes a prestressed anchor rod 200 and a support shell 300 embedded in the concrete buffer layer, the support shell 300 is an arc-shaped structure with an opening toward one side of the surrounding rock 803, the prestressed anchor rod 200 is connected to the support shell 300 and fixed in the surrounding rock 803; the annular pressure-yielding support structure includes a multi-section support frame 100, a plurality of prestressed tensioning structures 500 and a plurality of pressure-yielding support structures 600, the annular pressure-yielding support structure is arranged to form a support ring, and the prestressed tensioning structure 500 and the pressure-yielding support structure 600 both have a degree of freedom along the tangent direction of the support ring.

[0044] Compared with the prior art, the interlocking tunnel pressure-yielding support structure provided by the present invention has an annular pressure-yielding support structure and a radial pressure-yielding support structure in the support ring. The prestressed release structure 500 and the pressure-yielding support structure 600 of the annular pressure-yielding support structure respectively cooperate to realize the annular prestressed release and pressure-yielding retraction of the support ring; the concrete buffer layer, prestressed anchor rods 200 and support shell 300 of the radial pressure-yielding support respectively cooperate to realize the radial prestressed release and pressure-yielding retraction of the support ring; when the tunnel is deformed, the radial and annular pressure-yielding support structures are ensured to be stable and safe through the coordinated deformation of the radial and annular pressure-yielding support structures, and the pressure-yielding limit state is entered synchronously, thereby improving the stability of the support structure; the problem that the existing single pressure-yielding measure cannot meet the support measures for soft rock tunnels with large deformation is solved.

[0045] The concrete buffer layer includes a primary concrete buffer layer and a secondary concrete buffer layer 801 sprayed in sequence along the thickness direction. The primary concrete buffer layer is sprayed on the surface of the surrounding rock 803. The primary concrete buffer layer includes a first concrete buffer layer 800 and a second concrete buffer layer 802. The prestressed anchor rod 200 and the support shell 300 are installed on the outside of the first concrete buffer layer 800. The second concrete buffer layer 802 is sprayed on the outside of the first concrete buffer layer 800 and is embedded with the support shell 300 and the annular yield support structure; the secondary concrete buffer layer 801 is sprayed on the outside of the second concrete buffer layer 802 and the support shell 300. The secondary concrete buffer layer 801 solidifies and wraps the support shell 300 and the prestressed anchor rod 200 in the concrete buffer layer.

[0046] First, after spraying the first concrete buffer layer 800 on the surface of the surrounding rock 803, the prestressed anchor rod 200 and the support shell 300 are installed; after the installation is completed, the second concrete buffer layer 802 is sprayed on the first concrete buffer layer 800 and the outer surface of the installed prestressed anchor rod 200 and the support shell 300 to form an embedded structure. Finally, after the pressure is released, the secondary concrete buffer layer 801 is sprayed to completely cover it.

[0047] A plurality of groups of prestressed anchor rods 200 and a support shell 300 are arranged between the first concrete buffer layer 800 and the second concrete buffer layer 802. The concrete buffer layer and the plurality of groups of prestressed anchor rods and the support shell form an integral structure to realize radial yield support.

[0048] See also Figures 3 to 6The radial yield support includes a prestressed anchor rod 200 and a support shell 300, wherein the prestressed anchor rod 200 can be an existing anchor rod, and the prestressed anchor rod 200 extends into the first concrete buffer layer 800 and the surrounding rock 803 along the radial direction of the tunnel to form radial support for the tunnel. The first end of the prestressed anchor rod 200 is fixed in the surrounding rock 803, and the second end of the prestressed anchor rod 200 extends from the surrounding rock 803 into the tunnel. The support shell 300 is installed at the second end of the prestressed anchor rod 200, and the open end of the support shell 300 is attached to the surface of the first concrete buffer layer of the tunnel, so that the middle part of the arc-shaped support shell 300 protrudes toward the tunnel.

[0049] The prestressed anchor rod 200 can be a rod or an anchor pipe. The first end of the prestressed anchor rod 200 is anchored in the rock mass, and the second end of the prestressed anchor rod 200 passes through the support shell 300 and is fixed to the surface of the surrounding rock 803 by means of anchor bolts. The anchor bolts are located in the circumference of the support shell 300.

[0050] An elastic member may be provided inside the rod of the prestressed anchor rod 200, and the prestressing force can be released by releasing the elastic member. The prestressed anchor rod 200 can be set as a retractable sleeve rod structure, and an elastic member is added to the inner cavity of the sleeve rod. The elastic member is always kept in a compressed state during construction. After the construction is completed, the elastic member is released, and the sleeve rod is driven by the elastic member to extend to apply prestressing force to the surrounding rock 803.

[0051] The prestressed anchor rod 200 can also be realized by installing a hydraulic or pneumatic jack in the hollow casing. After the prestressed anchor rod 200 is installed, the jack is opened to release the prestress.

[0052] The second end of the prestressed anchor rod 200 is provided with a limiting annular step. The prestressed anchor rod 200 penetrates the support shell 300 from top to bottom, so that the limiting annular step fits on the outer end surface of the support shell 300. The lower end of the prestressed anchor rod 200 extends from the lower end of the support shell 300, and a limiting structure such as a nut is installed on the extended part. Optionally, a washer is added to the limiting annular step, and the washer increases the contact area between the limiting annular step and the support shell 300. A washer is also provided at the lower end of the support shell 300, and the washer is fixed to the prestressed anchor rod 200 through a nut and other structures.

[0053] like Figure 3 and Figure 4As shown, the prestressed anchor rod 200 includes multiple sections of casing, specifically including a lower section 201, a middle section 202 and an upper section 203; the lower section 201 is a tube body with uniform diameters at the top and bottom, and the lower section 201 is closed at the bottom and open at the bottom. The middle section 202 and the upper section 203 are both two-section structures, wherein the tube diameter of the lower section is smaller than the tube diameter of the upper section, the outer diameter of the upper section is consistent with the outer diameter of the lower section 201, and the outer diameter of the lower section is smaller than the inner diameter of the upper section; the lower section of the middle section 202 extends to the inner cavity of the upper section of the lower section 201, and the lower section of the upper section 203 extends to the inner cavity of the upper section of the middle section 202. A stopper is provided in the cavity of the lower section 201, the stopper is coaxial with the lower section 201, and the upper end of the stopper does not exceed the upper end surface of the lower section 201. The outer side of the limiting member is sleeved with a pressure-releasing member 204, which is an annular structure. The pressure-releasing member 204 is located in the inner cavity of the lower segment 201, and the lower end of the middle segment 202 abuts against the upper end surface of the pressure-releasing member 204. A pre-compression disc spring 205 is arranged in the cavity at the upper end of the middle segment 202, and the lower end of the pre-compression disc spring 205 abuts against the limiting step formed at the connection between the upper segment and the lower segment of the middle segment 202. The upper end of the pre-compression disc spring 205 is sleeved on the outer side of the lower segment of the upper segment 203 and abuts against the limiting step formed by the upper segment and the lower segment of the upper segment 203. Optionally, the pressure-releasing member 204 can be made of materials such as foam metal.

[0054] After the construction and installation of the prestressed anchor rod 200 is completed, the pre-compression disc spring 205 is first released, and the prestressed anchor rod 200 applies a prestress to the surrounding rock 803; as the surrounding rock 803 deforms, the force applied by the surrounding rock 803 is greater than the prestress of the prestressed anchor rod 200, the prestressed anchor rod 200 is compressed, the pre-compression disc spring 205 and the pressure-releasing member 204 are compressed, and the prestressed anchor rod 200 is shortened.

[0055] The support shell 300 of the radial yield support includes an outer curved plate 301, an inner curved plate 302 and a yield filling layer 303. The inner curved plate 302 is located on the side close to the surrounding rock 803. The inner curved plate 302 and the outer curved plate 301 are arranged in parallel. An interlayer space is formed between the inner curved plate 302 and the outer curved plate 301. The yield filling layer 303 is located in the interlayer space, and the yield filling layer 303 has the freedom to bend along the thickness direction.

[0056] The interlayer space between the outer curved plate 301 and the inner curved plate 302 is filled with a pressure-yielding filling layer 303. Under the action of external force, the pressure-yielding filling layer 303 can achieve buckling deformation in the thickness direction and form a rebound force on the outside to achieve the purpose of pressure-yielding. After the outer curved plate 301 is squeezed and deformed, the outer curved plate 301 deforms toward the interlayer space, and the outer curved plate 301 squeezes the pressure-yielding filling layer 303 located in the interlayer space; the pressure-yielding filling layer 303 is deformed, but because the pressure-yielding filling layer 303 applies a reverse squeezing force to the surrounding rock 803 while deforming, as the force applied by the surrounding rock 803 reaches the maximum value, the deformation of the pressure-yielding filling layer 303 reaches the maximum, and finally the pressure-yielding filling layer 303 and the surrounding rock 803 reach a balanced state.

[0057] The thickness and strength of the inner curved plate 302 are greater than those of the outer curved plate 301. In the above-mentioned yielding process, the outer curved plate 301, the yielding filling layer 303 and the inner curved plate 302 are deformed as a whole, and the deformation amount of the inner curved plate 302 is the smallest.

[0058] The pressure-releasing filling layer 303 in the interlayer space of the supporting shell 300 is a porous structure. Alternatively, the pressure-releasing filling layer 303 is made of metal and is compressible along the thickness direction of the shell; the pressure-releasing filling layer 303 is a honeycomb plate structure or a corrugated plate structure with multiple layers connected in sequence.

[0059] The material selected for the pressure-releasing filling layer 303 needs to have supporting strength and compressibility. In the first embodiment, the pressure-releasing filling layer 303 can be made of non-metallic materials, such as artificial SAP hole concrete and the like. In the second embodiment, the pressure-releasing filling layer 303 can be made of metal materials, such as foam metal, honeycomb metal plate, corrugated metal plate and metal block 606 structure.

[0060] The porosity of foam metal reaches more than 90%, and it is a porous metal with certain strength and rigidity. It has the property of being compressible.

[0061] When a honeycomb metal plate is arranged in the pressure-releasing filling layer 303, the aperture direction of the honeycomb metal plate is perpendicular to the thickness direction of the pressure-releasing filling layer 303, and the aperture of the honeycomb metal plate gradually decreases from the outside to the inside along the thickness direction. The honeycomb metal plate can be made of steel plate. The honeycomb metal plate is composed of a whole and a plurality of pieces. When the honeycomb metal plate is composed of a plurality of pieces, two adjacent honeycomb metal plates are welded and fixed. The honeycomb metal plate is connected to the inner curved plate 302, and the honeycomb metal plate is connected to the outer curved plate 301 by welding or bolts.

[0062] When a corrugated metal plate is arranged in the yield filling layer 303, multiple corrugated metal plates are stacked in the thickness direction, and multiple corrugated metal plates are stacked in an interlaced manner to form a gap between two adjacent corrugated metal plates, so as to avoid the two corrugated metal plates being closely fitted and losing the yield deformation. The arc diameter corresponding to the corrugations of the multiple corrugated metal plates gradually decreases from the outside to the inside along the thickness direction of the yield filling layer 303. Two adjacent corrugated metal plates, the corrugated metal plate and the inner arc plate 302, and the corrugated metal plate and the outer arc plate 301 can all be connected by welding.

[0063] The metal block 606 structure is provided with an array of relief holes 607, which can realize the compression deformation of the metal block 606. The aperture of the relief holes 607 gradually decreases from the outside to the inside along the radial direction of the support shell 300, so that the bearing capacity of the pressure-releasing filling layer 303 gradually increases from the outside to the inside. When subjected to force, the outer arc plate 301 and the outer structure of the pressure-releasing filling layer 303 are first compressed and deformed.

[0064] The support shell 300 achieves a gradient structure of rigidity on the outside and flexibility on the inside by filling the interlayer space of the shell with a pressure-yielding filling layer 303, so that it can bear the load of the surrounding rock 803 and deform in an orderly manner.

[0065] Regarding the outer shell structure of the supporting shell 300 , the thickness of the outer arc plate 301 is smaller than the thickness of the inner arc plate 302 ; the thickness of the outer arc plate 301 gradually becomes thinner from the center toward the edge.

[0066] The outer curved plate 301 and the inner curved plate 302 of the support shell 300 are both made of steel plates, and the thickness of the outer curved plate 301 gradually changes from thin to thick from the edge to the center, forming a gradual gradient structure in the horizontal direction of the anchor. The outer curved plate 301 of the support shell 300 is slightly thinner than the inner curved plate 302. Under the action of load, the outer curved plate 301 can reach the yield strength first, and the buckling deformation of the outer curved plate 301 realizes the compression deformation of the anchor.

[0067] When subjected to the pressure of the surrounding rock 803, the outer arc plate 301 is deformed first, and the force is transferred to the pressure-yielding filling layer 303, and the pressure of the surrounding rock 803 is buffered by the pressure-yielding filling layer 303 to achieve support balance, so that the support shell 300 forms a stable state.

[0068] When the load reaches a certain value, the thinner part of the outer curved plate 301 of the support shell 300 begins to buckle and deform, causing the anchor as a whole to deform relative to the surrounding rock 803, and the entire anchor undergoes compression deformation relative to the surrounding rock 803. When the anchor continues to bear the load, when the load further increases to a certain value, the outer curved plate 301 and the inner curved plate 302 of the support shell 300 deform to a certain extent, and the buckling deformation stops. At this time, the outer curved plate 301 of the support shell 300 reaches a buckled state.

[0069] In some possible embodiments, see Figure 5 The support shell 300 is a hemispherical structure; the end face of the open end of the support shell 300 fits with the surrounding rock 803 at the top of the tunnel, and the closed end of the support shell 300 faces downward; the outer arc plate 301 and the inner arc plate 302 have a sealing end plate 304 on the side facing the open end, and the sealing end plate 304 is used to close the interlayer space; the edge of the sealing end plate 304 close to the outer arc plate 301 has an outer edge protrusion protruding outward, and the outer edge protrusion fits on the wall of the surrounding rock 803.

[0070] The edge of the outer curved plate 301 of the support shell 300 and the edge of the inner curved plate 302 are located on the same horizontal plane, the outer curved plate 301 and the inner curved plate 302 are parallel, and the outer curved plate 301 and the inner curved plate 302 are both hemispherical, forming a sandwich space between the two; at the edge of the sandwich space, there is a sealing end plate 304 connecting the outer curved plate 301 and the inner curved plate 302, and the sealing end plate 304 is attached to the wall of the surrounding rock 803. The outer edge of the sealing end plate 304 is convex and attached to the wall of the surrounding rock 803 to increase the degree of attachment. A deformation reserved groove is opened on the wall of the surrounding rock 803 to allow the support shell 300 to deform.

[0071] like Figure 6 As shown, in another embodiment, the cross-sectional direction of the support shell 300 is set at an angle with the length direction of the tunnel, and two cross-connected support shells 300 form a cross-beam structure; the mezzanine spaces in the two support shells 300 are connected, and the prestressed anchor rods 200 in the mezzanine space vertically penetrate the center of the connection between the two support shells 300; vertical end plates are provided around the sides of the support shells 300, and the vertical end plates are concave toward the mezzanine space.

[0072] Both support shells 300 are arc-shaped structures. The circumferences of the two support shells 300 are set at an angle with the axial direction of the tunnel, and the two support shells 300 are symmetrically arranged along the axial direction of the tunnel. The length directions of the two support shells 300 are vertical. The two support shells 300 are cross-connected to form a cross-beam structure. The outer arc surfaces of the two support shells 300 are flush, the inner arc surfaces are flush, and the interlayer spaces are connected. An integral pressure-relief filling layer 303 is formed in the connected interlayer spaces. Corrugated steel plates can be used in the pressure-relief filling layer 303. The corrugated steel plates are horizontally arranged and staggered and stacked in the longitudinal direction. The pressure-relief filling layer 303 formed by stacking the corrugated steel plates can be compressed and deformed under load.

[0073] The support shell 300 also includes vertical end plates arranged on both sides of the support shell 300 in the width direction. The vertical end plates are steel plates that are recessed toward the inner side of the mezzanine space. Under the action of pressure, the vertical end plates bend and deform into the mezzanine space, thereby avoiding problems such as outward expansion and deformation of the support shell 300 and squeezing the side of the anchor to spray concrete.

[0074] To ensure that the anchor is in close contact with the surrounding rock 803, the ends of the inner curved plate 302 and the outer curved plate 301 in the length direction are also wrapped with vertical end plates, which are consistent with the vertical end plates in the width direction of the support shell 300. The edges of the vertical end plates on one side close to the outer curved plate 301 are all provided with outer edge protrusions protruding outward, and the outer edge protrusions are in close contact with the surrounding rock 803.

[0075] Or the end of the outer arc plate 301 extends downward to be flush with the end of the inner arc plate 302, and the ends of the two in the length direction are connected by means of a sealing end plate 304, and the outer edge of the sealing end plate 304 has a protrusion protruding outward, which fits against the surrounding rock 803.

[0076] The support frame body 100 is a single-layer support structure or a multi-layer support structure. The support frame body 100 can be made of I-beams, H-beams or a combination of the two. The support frame body 100 can be fixedly connected to the annular yielding support structure and the radial yielding support structure by welding, bolting, concrete pouring and the like. In particular, the radial yielding support structure is provided with an anchor expansion sleeve 400 on its outer side, which is connected to the support frame body 100. The prestressed tensioning structure 500 of the annular yielding support structure is connected to the yielding support structure 600.

[0077] In some possible embodiments, see Figures 7 and 8The prestressed tensioning structure 500 includes a first positioning plate 503, a second positioning plate 504 and a telescopic member. The two ends of the telescopic member are respectively connected to the first positioning plate 503 and the second positioning plate 504. The telescopic member is respectively connected to the support frame body 100 and the pressure support structure 600 by means of the first positioning plate 503 and the second positioning plate 504; the telescopic member is always in a retracted state when assembled with the support frame body 100; 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.

[0078] The first positioning plate 503 and the second positioning plate 504 are respectively oriented toward the support frame body 100 and the pressure support structure 600, the first positioning plate 503 is connected to the support frame body 100, and the second positioning plate 504 is connected to the pressure support structure 600. The telescopic member is located between the first positioning plate 503 and the second positioning plate 504, and the telescopic member is telescopic along its own length direction to drive the first positioning plate 503 and the second positioning plate 504 to move closer or farther away.

[0079] When the telescopic member extends along its own length direction, it drives the first positioning plate 503 and the second positioning plate 504 to move away from each other, thereby expanding the support ring and applying pressure to the surrounding rock 803 by the support ring.

[0080] When the force applied by the surrounding rock 803 is greater than the pre-stress of the telescopic member, the telescopic member contracts under the pressure of the surrounding rock 803, driving the first positioning plate 503 and the second positioning plate 504 to approach each other, 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 803 is achieved.

[0081] A clearance space for installing the telescopic member is formed between the first positioning plate 503 and the second positioning plate 504. 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.

[0082] like Figure 7 As shown, multiple telescopic parts may include pneumatic jacks, hydraulic jacks 502 and mechanical jacks 501. During construction, a pneumatic jack or hydraulic jack 502 is installed in the middle of the make way space, and a mechanical jack 501 is installed on both sides thereof. Active support force is provided by the combination of pneumatic / hydraulic jacks 502 and mechanical jacks 501, 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 parts include hydraulic jacks 502 and mechanical jacks 501 located on both sides of the hydraulic jacks 502. 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.

[0083] For easy installation, the prestressed device further includes a retractable housing, which includes two flange mounting plates 703 and a sleeve structure 700. The sleeve structure 700 includes an inner cylinder 701 and an outer cylinder 702 which are sleeved and connected. The outer cylinder 702 slides along the length direction of the inner cylinder 701. The inner cavity of the retractable housing is used to accommodate the prestressed tensioning structure 500. Fig.11 shown.

[0084] The prestressed tensioning structure 500 is located in the inner cavity of the retractable shell, and the first positioning plate 503 and the second positioning plate 504 are respectively connected to two flange mounting plates 703; bolt holes are provided on the two flange mounting plates 703, and the two flange mounting plates 703 are respectively connected to the ends of the support frame 100 and the pressure support structure 600 by means of bolts or welding.

[0085] In addition, if Figure 8 As shown, the telescopic member can also adopt a pre-stressed spring structure 505, and the pre-stressed spring 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, and the released spring applies force to the support ring and drives the support ring to expand outward, thereby squeezing the surrounding rock 803. Specifically, the sleeve structure 700 is divided into three layers, and two adjacent layers can slide relative to each other. A pre-stressed spring structure 505 is installed in the inner cavity between the first layer and the second layer; a pressure-releasing member is installed in the inner cavity between the second layer and the third layer, and the pressure-releasing member includes an upper and lower fixed plate 508 and two vertical side plates 507 connecting the two fixed plates 508, and the two vertical side plates 507 are symmetrically arranged on both sides of the fixed plate 508. The vertical side plate 507 is an arc-shaped plate that is concave inwardly. When the vertical side plate 507 is squeezed by external force, it will be concave and deformed inwardly to avoid affecting the structure outside the pressure-releasing member.

[0086] In some possible embodiments, see Figures 9 and 10 The pressure-releasing support structure 600 includes a first pressure-bearing plate 602, a second pressure-bearing plate 603 and a pressure-releasing element; the two force-bearing ends of the pressure-releasing element are respectively connected to the first pressure-bearing plate 602 and the second pressure-bearing plate 603, and the pressure-releasing element is respectively connected to the pressure-releasing support structure 600 and the next section of the support frame 100 by means of the first pressure-bearing plate 602 and the second pressure-bearing plate 603.

[0087] The first pressure plate 602 and the second pressure plate 603 are arranged in parallel and spaced apart, and a pressure relief space is formed between the first pressure plate 602 and the second pressure plate 603, 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 602 and the second pressure plate 603, and the pressure relief element has a deformation tendency along the direction perpendicular to the connection line of the first pressure plate 602 and the second pressure plate 603. When the pressure relief element is squeezed by the first pressure plate 602 and the second pressure plate 603, the pressure relief element is compressed and deformed, and it is deformed along the direction perpendicular to the connection line of the first pressure plate 602 and the second pressure plate 603, and the displacement of the first pressure plate 602 and the second pressure plate 603 is satisfied while applying pressure to the first pressure plate 602 and the second pressure plate 603, thereby maintaining the force stability of the support ring.

[0088] The pressure-releasing element includes two symmetrically arranged concave pressure-releasing plates 601; a pressure-releasing space is formed between the first pressure-bearing plate 602 and the second pressure-bearing plate 603, and the concave pressure-releasing plate 601 is located at the edge of the pressure-releasing space and bulges toward the center of the pressure-releasing space when under pressure.

[0089] A pair of flexures are provided between the two concave pressure plates 601, and both flexures are arc-shaped plates; the open ends of the two flexures face the first pressure plate 602 and the second pressure plate 603 respectively, and the closed ends of the two flexures fit together.

[0090] The two ends of the concave yield plate 601 in the length direction are respectively connected to the first pressure plate 602 and the second pressure plate 603. The two concave yield plates are symmetrically arranged at the two edges of the yield space, and the convex direction of the concave yield plate is toward the space between the two concave yield plates. Under the extrusion force of the first pressure plate 602 and the second pressure plate 603, 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 602 and the second pressure plate 603 decreases.

[0091] Optionally, the concave portion allows the thickness of the pressing plate 601 to gradually decrease from both ends toward the middle.

[0092] A pair of flexures are provided between the two concave pressure plates 601 , and both flexures are arc-shaped plates 604 ; the open ends of the two flexures face the first pressure plate 602 and the second pressure plate 603 respectively, and the closed ends of the two flexures fit together.

[0093] The two buckling members are located in the pressure relief space between the two concave pressure relief plates 601. The two buckling members are arc plates 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 602, and both ends of the first arc plate are connected to the first pressure plate 602. On the contrary, the opening of the second arc plate faces the second pressure plate 603, and both ends of the second arc plate are connected to the second pressure plate 603. 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.

[0094] In addition, a support plate 605 with a semicircular cross section is provided on the inner side of the flexure. The two semicircular support plates 605 are located on the inner sides of the first curved plate and the second curved plate respectively. The two support plates 605 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 602; the second straight plate is correspondingly arranged in the inner cavity surrounded by the second curved plate and the second pressure-bearing plate 603.

[0095] Taking the first support plate as an example, the first support plate is an arc-shaped plate body 604 with a semicircular cross section, the open end of the arc-shaped plate body 604 faces one side of the first supporting plate, and both ends of the arc-shaped plate body 604 are connected to the first supporting plate. The arc-shaped plate body 604 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.

[0096] 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.

[0097] 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.

[0098] like Fig.10 As shown, the pressure-releasing element is a metal block 606, and the metal block 606 is provided with a plurality of rows of relief holes 607 along the length direction, and the diameter of the relief holes 607 gradually decreases or increases from the first pressure-bearing plate 602 to the second pressure-bearing plate 603. The metal block 606 is connected to the first pressure-bearing plate 602 and the second pressure-bearing plate 603 by welding or bolts.

[0099] For easy installation, the yield support structure includes a retractable shell, which includes two flange mounting plates 703 and a sleeve structure 700. The sleeve structure 700 includes an inner cylinder 701 and an outer cylinder 702. The outer cylinder 702 is sleeved on the outer side of the inner cylinder 701 and slides along the length direction of the inner cylinder 701. The inner cavity of the retractable shell is used to accommodate the yield support structure 600. Fig.11shown.

[0100] The yield support structure is located in the inner cavity of the retractable shell, and the first pressure plate 602 and the second pressure plate 603 are respectively connected to two flange mounting plates 703; bolt holes are provided on the two flange mounting plates 703, and the two flange mounting plates 703 are respectively connected to the prestressed device and the support frame 100 by bolts or welding.

[0101] Grouting holes 506 are provided at both ends of the telescopic shell of the prestressed tensioning structure 500 and the pressure-releasing support structure 600, and the grouting holes 506 are used to pour pressure-releasing concrete.

[0102] like Figures 1 to 13 As shown, a construction method of an interlocking tunnel pressure-yielding support structure is also provided, which adopts the above-mentioned interlocking tunnel pressure-yielding support structure and includes the following steps:

[0103] S1, excavation of the upper step of the tunnel, spraying of the first layer of radial yield concrete on the excavation contour surface;

[0104] S2, install prestressed anchor rods 200 and support shells 300 on the surface of the first layer of radial pressure-releasing concrete, and apply prestress to the anchor rods; at the same time, install the support frame 100, apply the locking anchor rods, and assemble the prestressed tensioning structure 500 and the pressure-releasing support structure 600;

[0105] S3, spraying a second layer of radial yield concrete, embedding the support shell 300 and the support frame body 100 in the second layer of radial yield concrete, forming a steel frame embedded structure;

[0106] S4, excavating the lower step of the tunnel, repeating the installation of the support frame 100, the prestressed tensioning structure 500 and the pressure-releasing support structure 600 in steps S1 and S2 for the lower step excavation contour surface;

[0107] S5, the compression support structure is made into a ring, and the prestressed release structure 500 is released, so that the compression support structure is squeezed and deformed toward the surrounding rock 803, and the diameter of the compression support structure is extended outward to form an active support force;

[0108] S6, spraying a secondary concrete buffer layer 801 to form an integral support structure;

[0109] S7, the surrounding rock 803 continues to be squeezed and deformed toward the excavation contour surface. When the pressure of the surrounding rock 803 is greater than the main force, the prestressed tensioning structure 500 bears the load and begins to compress and deform. As the surrounding rock 803 is squeezed and deformed toward the excavation contour surface, the diameter of the compression support structure is reduced; at the same time, the prestressed anchor rod 200 bears the load and is compressed and deformed;

[0110] S8. The surrounding rock 803 is continuously squeezed and deformed toward the excavation contour surface, and the support pressure of the surrounding rock 803 is continuously increased. When the pressure of the surrounding rock 803 is greater than the starting pressure of the yielding support structure 600, the yielding support structure 600 begins to compress and deform. At the same time, the support shell 300 is deformed under pressure. The annular yielding support structure and the radial yielding support structure are deformed in coordination until the pressure of the surrounding rock 803 and the support force reach a force balance.

[0111] Compared with the prior art, the construction method of the interlocking tunnel pressure-yielding support structure provided by the present invention adopts the above-mentioned interlocking tunnel pressure-yielding support structure and has all the beneficial effects thereof; when the tunnel is deformed, the radial and circumferential joint pressure-yielding coordinated deformation is achieved to ensure the stability and safety of the radial and circumferential pressure-yielding support structures, and the pressure-yielding limit state is entered synchronously, thereby improving the stability of the support structure; and the problem that the existing single pressure-yielding measure cannot meet the support measures for soft rock tunnels with large deformation is solved.

[0112] Specifically, after the excavation of the upper step of the tunnel is completed, the initial sprayed concrete layer 804 is sprayed on the excavation contour surface, and after solidification, the first layer of radial yield concrete is sprayed to form a first concrete buffer layer. Then, the prestressed anchor rod 200 and the support shell 300 are installed on the surface of the first layer of radial yield concrete, and the prestressed anchor rod 200 is released after the installation is completed; the support frame 100 is installed at the same time, and the locking anchor rod is installed at the support frame 100; the prestressed release structure 500 and the yield support structure 600 are assembled while the support frame 100 is installed.

[0113] After the installation is completed, a second layer of radial pressure relief concrete is sprayed on the support frame body 100 to form a second concrete buffer layer, completing the radial pressure relief structure. The support shell 300 and the support frame body 100 are embedded in the concrete structure layer to form a steel frame embedded structure. A steel mesh 805 is also laid in the second concrete buffer layer.

[0114] After the tunnel upper step support is completed, the tunnel lower step is excavated. After the tunnel lower step is excavated, the first layer of radial yield concrete is sprayed on the excavation contour surface, and the support frame 100, the prestressed tensioning structure 500 and the yield support structure 600 are installed. That is, the excavation contour surface of the tunnel lower step does not need to be provided with a radial yield support structure.

[0115] After the installation is completed, the steel frame embedded structure in step S3 and the steel frame structure in step S4 are connected to form a support ring; after the support ring is assembled, the prestressed release structure 500 is released to squeeze and deform the support ring toward the surrounding rock 803, and the diameter of the support ring is extended outward to increase, and the support ring actively applies a supporting force to the surrounding rock 803 to form an active support force. Then, a secondary concrete buffer layer 801 is sprayed on the support ring to form an overall support structure.

[0116] The surrounding rock 803 is continuously squeezed and deformed toward the excavation contour surface, and the support pressure of the surrounding rock 803 is continuously increased. When the pressure of the surrounding rock 803 is greater than the main force, the prestressed tensioning structure 500 bears the load and begins to compress and deform. As the surrounding rock 803 is squeezed and deformed toward the excavation contour surface, the diameter of the support ring is reduced, and the support ring begins to deform and yield to the pressure.

[0117] As the surrounding rock 803 continues to be squeezed and deformed toward the excavation contour surface, the pressure of the surrounding rock 803 on the support continues to increase. When the pressure of the surrounding rock 803 is greater than the starting force of the yielding support structure 600, the yielding support structure 600 begins to compress and deform. Under the joint compression and deformation of the prestressed tensioning structure 500 and the yielding support structure 600, the surrounding rock 803 is squeezed and deformed toward the excavation contour surface, and the diameter of the support ring continues to shrink. As the support ring continues to shrink and deform to yield, the surrounding rock 803 continues to squeeze and deform toward the excavation contour surface to release energy, thereby reducing the pressure of the surrounding rock 803 on the support structure. The energy of the surrounding rock 803 is continuously released until the pressure of the surrounding rock 803 and the support force reach a force balance, so that the support structure achieves a stable state.

[0118] When the tunnel deforms, the annular compression support structure and the radial compression support structure deform in coordination to ensure that the annular compression support structure and the radial compression support structure are stable and safe, and enter the compression limit state simultaneously.

[0119] 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 interlocking tunnel pressure-yielding support structure is characterized by: It includes radial pressure-yielding support structure and annular pressure-yielding support structure; The radial yield support structure comprises a concrete buffer layer and a radial support assembly; the concrete buffer layer covers the surface of the surrounding rock; the support assembly comprises a prestressed anchor rod (200) embedded in the concrete buffer layer and a support shell (300); the support shell (300) is an arc-shaped structure with an opening facing one side of the surrounding rock; the prestressed anchor rod (200) is connected to the support shell (300) and fixed in the surrounding rock; The support shell (300) comprises an outer curved plate (301), an inner curved plate (302) and a pressure-yielding filling layer (303); the inner curved plate (302) is located on a side close to the surrounding rock; the inner curved plate (302) and the outer curved plate (301) are arranged in parallel; an interlayer space is formed between the inner curved plate (302) and the outer curved plate (301); the pressure-yielding filling layer (303) is located in the interlayer space; the pressure-yielding filling layer (303) has a degree of freedom to bend along the thickness direction; the bearing capacity of the pressure-yielding filling layer (303) gradually increases from the outside to the inside; when subjected to force, the outer structures of the outer curved plate (301) and the pressure-yielding filling layer (303) are first compressed and deformed; The annular pressure-releasing support structure comprises a multi-section support frame (100), a plurality of prestressed release structures (500) and a plurality of pressure-releasing support structures (600); the annular pressure-releasing support structure is arranged to form a support ring, and both the prestressed release structure (500) and the pressure-releasing support structure (600) have a degree of freedom along the tangent direction of the support ring; The pressure-yielding support structure (600) comprises a first pressure-bearing plate (602), a second pressure-bearing plate (603) and a pressure-yielding element; two force-bearing ends of the pressure-yielding element are respectively connected to the first pressure-bearing plate (602) and the second pressure-bearing plate (603); the pressure-yielding element is respectively connected to the pressure-yielding support structure (600) and the next section of the support frame body (100) by means of the first pressure-bearing plate (602) and the second pressure-bearing plate (603); The pressure-releasing element comprises two symmetrically arranged inwardly concave pressure-releasing plates (601); a pressure-releasing space is formed between the first pressure-bearing plate (602) and the second pressure-bearing plate (603); the inwardly concave pressure-releasing plate (601) is located at the edge of the pressure-releasing space and convexly deforms toward the center of the pressure-releasing space when under pressure; A pair of flexures are provided between the two inwardly concave pressure plates (601), and both flexures are arc-shaped plates; the open ends of the two flexures face the first pressure plate (602) and the second pressure plate (603), respectively, and the closed ends of the two flexures fit together.

2. The interlocking tunnel pressure-yielding support structure according to claim 1 is characterized in that: The concrete buffer layer comprises a primary concrete buffer layer and a secondary concrete buffer layer (801) sprayed in sequence along the thickness direction, the primary concrete buffer layer is sprayed on the surface of the surrounding rock (803), the primary concrete buffer layer comprises a first concrete buffer layer (800) and a second concrete buffer layer (802), the prestressed anchor rod (200) and the support shell (300) are installed on the outside of the first concrete buffer layer (800), the second concrete buffer layer (802) is sprayed on the outside of the first concrete buffer layer (800), and is embedded with the support shell (300) and the annular yield support structure; the secondary concrete buffer layer (801) is sprayed on the outside of the second concrete buffer layer (802) and the support shell (300), and the secondary concrete buffer layer (801) solidifies to enclose the support shell (300) and the prestressed anchor rod (200) in the concrete buffer layer.

3. The interlocking tunnel pressure-yielding support structure according to claim 1 is characterized in that: The support shell (300) is a hemispherical structure; the end face of the open end of the support shell (300) is in contact with the surrounding rock at the top of the tunnel, and the closed end of the support shell (300) faces downward; the outer arc plate (301) and the inner arc plate (302) have a sealing end plate (304) on the side facing the open end, and the sealing end plate (304) is used to close the interlayer space; the edge of the sealing end plate (304) close to the outer arc plate (301) has an outer edge protrusion protruding outward, and the outer edge protrusion is in contact with the surrounding rock wall.

4. The interlocking tunnel pressure-yielding support structure according to claim 1 is characterized in that: The cross-sectional direction of the support shell (300) is set at an angle with the length direction of the tunnel, and the two cross-connected support shells (300) form a cross-beam structure; the interlayer spaces in the two support shells (300) are connected, and the prestressed anchor rod (200) in the interlayer space vertically penetrates the center of the connection between the two support shells (300); vertical end plates are provided around the side of the support shell (300), and the vertical end plates are concave toward the interlayer space.

5. The interlocking tunnel pressure-yielding support structure according to claim 1 is characterized in that: The prestressed release structure (500) comprises a first positioning plate (503), a second positioning plate (504) and a telescopic member, wherein the two ends of the telescopic member are respectively connected to the first positioning plate (503) and the second positioning plate (504), and the telescopic member is respectively connected to the support frame body (100) and the pressure-releasing support structure (600) by means of the first positioning plate (503) and the second positioning plate (504); the telescopic member is always in a contracted state during assembly and construction with the support frame body (100); 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.

6. The construction method of the interlocking tunnel pressure-yielding support structure is characterized in that: The interlocking tunnel pressure-yielding support structure according to any one of claims 1 to 5 is adopted, and includes the following steps: S1, excavation of the upper step of the tunnel, spraying of the first layer of radial yield concrete on the excavation contour surface; S2, installing prestressed anchor rods (200) and support shells (300) on the surface of the first layer of radial pressure-yielding concrete, and applying prestress to the anchor rods; at the same time, installing the support frame (100), applying the locking anchor rods, and assembling the prestressed tensioning structure (500) and the pressure-yielding support structure (600); S3, spraying a second layer of radial yield concrete, embedding the support shell (300) and the support frame body (100) in the second layer of radial yield concrete, and forming a steel frame embedded structure; S4, excavating the lower step of the tunnel, repeating the installation of the support frame body (100), the prestressed tensioning structure (500) and the pressure-releasing support structure (600) in steps S1 and S2 for the lower step excavation contour surface; S5, the compression support structure is made into a ring shape, and the prestressed release structure (500) is released, so that the compression support structure is squeezed and deformed toward the surrounding rock, and the diameter of the compression support structure is extended outward to form an active support force; S6, spraying a secondary concrete buffer layer to form an integral support structure; S7, the surrounding rock continues to be squeezed and deformed toward the excavation contour surface. When the surrounding rock pressure is greater than the main force, the prestressed tensioning structure (500) bears the load and begins to compress and deform. As the surrounding rock is squeezed and deformed toward the excavation contour surface, the diameter of the compression support structure is reduced; at the same time, the prestressed anchor rod (200) bears the load and compresses and deforms; S8. The surrounding rock continues to be squeezed and deformed toward the excavation contour surface, and the surrounding rock pressure on the support continues to increase. When the surrounding rock pressure is greater than the yielding starting force of the yielding support structure (600), the yielding support structure (600) begins to compress and deform; at the same time, the support shell (300) is deformed under pressure; the annular yielding support structure and the radial yielding support structure are deformed in coordination until the surrounding rock pressure and the support force reach a force balance.

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