Nested cavity structure for lining reinforcement and method of construction thereof

Abstract

The present application relates to a kind of nested cavity structure for lining reinforcement and its construction method, is deployed in the inside of segment lining of existing tunnel, is formed by the splicing of many cavity units;Single cavity unit includes annularly curved steel plate, and annular male cavity and female cavity are arranged on longitudinal two sides;The outside of male cavity is provided with rotatable T-shaped key, and the outside of female cavity is provided with a one-way slot;When cavity unit is annularly spliced, joint steel pipe is inserted between male cavity;When cavity unit is longitudinally spliced, male cavity faces female cavity, rotatable T-shaped key is inserted into one-way slot and rotates.The present application can form reinforcing area continuously distributed along the longitudinal direction of tunnel according to need by distributed cavity structure and its connecting process, avoid the insufficient rigidity of conventional single cavity, have the reliability of conventional steel plate and lining structure using anchor bolt connection, also can reduce cavity height according to need to adapt to limit requirement, can effectively improve the reinforcement quality of lining structure.

Description

Technical Field

[0001] This invention relates to the field of underground engineering construction technology, specifically to a nestable cavity structure for lining reinforcement and its construction method. Background Technology

[0002] Urban core areas inevitably face extreme weather events, such as torrential rains, floods, prolonged heat waves, and strong winds. These extreme climatic conditions pose a severe challenge to the safety and durability of underground space structures. Since existing underground projects are often integral parts of dense building complexes and transportation networks in urban built-up areas, complete demolition and reconstruction are not only extremely costly but also technically difficult to implement at present, and could severely disrupt urban operations in severe cases. Therefore, in the face of increasingly severe climate and environmental risks, it is essential to adopt more systematic, efficient, and reliable reinforcement and maintenance measures for underground space structures to enhance their disaster resistance and environmental adaptability. This will significantly improve the overall protective performance of underground projects without large-scale renovations, maximize their service life, and ensure the continuous and stable operation of the city's lifeline.

[0003] Currently, conventional underground structure lining reinforcement measures mainly involve bonding composite fiber cloth / boards, steel plates, and secondary concrete lining. However, composite fiber cloth / boards cannot effectively withstand pressure, steel plates are at risk of corrosion, and secondary concrete lining is bulky, ineffective, and often fails to meet existing clearance requirements. Recently, rectangular multi-cavity structure reinforcement measures have emerged, primarily replacing traditional steel plates with multi-cavity structures and wrapping the steel plates with composite fiber materials. This significantly improves performance, but also has drawbacks such as high cost, reliance on adhesives for bonding with existing lining structures, and stringent clearance requirements for reinforcement work.

[0004] Therefore, it is necessary to propose new measures to overcome the above-mentioned shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide a nestable cavity structure for lining reinforcement and its construction method, so as to solve the problems of high cost, poor integration with existing lining structures, and high requirements for clearance in existing lining reinforcement measures.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A nestable cavity structure for lining reinforcement is provided, which is deployed inside the segment lining of an existing tunnel and is composed of numerous cavity units spliced ​​together.

[0008] The cavity unit includes a circumferentially bent steel plate that unfolds into a rectangle. On both sides of the steel plate are circumferential male and female cavities, which are closed to the steel plate and have circumferential through channels. Along the circumferential direction of the tunnel, a rotatable T-shaped key is provided on the outer side of the male cavity, and a straight groove is provided on the outer side of the female cavity.

[0009] When the cavity units are spliced ​​circumferentially, a joint steel pipe is inserted between the male cavities of two adjacent circumferential cavity units to achieve circumferential splicing;

[0010] When the cavity units are spliced ​​longitudinally, in two longitudinally adjacent cavity units, the male cavity of one cavity unit faces the female cavity of the other cavity unit, and the rotatable T-shaped key of the male cavity is inserted into the slot of the female cavity and rotated to achieve longitudinal splicing.

[0011] Furthermore, a circumferential square cavity is provided in the longitudinal center of the steel plate, the square cavity being closed with the steel plate and having a circumferential through channel;

[0012] When the cavity units are spliced ​​circumferentially, a joint steel pipe is inserted between the square cavities of two adjacent circumferential cavity units to achieve circumferential splicing.

[0013] Furthermore, the steel plate is provided with post-installed anchor bolts, and the steel plate is fixed to the segment lining by the post-installed anchor bolts.

[0014] Furthermore, the rotatable T-key includes a horizontal bar with a rotating rod perpendicular to it connected to the horizontal bar.

[0015] The end of the rotating rod is provided with a hollow internal threaded groove coaxial with it. A threaded screw is inserted into the hollow internal threaded groove, and the end of the threaded screw is vertically fixed to the longitudinal outer side of the male cavity.

[0016] Furthermore, the outer wall of the rotating rod is provided with a rotating handle, and the outer wall of the rotating rod between the rotating handle and the straight crossbar is provided with an external thread, and a circular washer and a hexagonal nut are installed.

[0017] Furthermore, the cavity is filled with cement mortar, and only the upper half of the joint steel pipe insertion area is filled, while the rest is completely filled.

[0018] Furthermore, the square cavity is filled with cement mortar, and only the upper half of the joint steel pipe insertion area is filled, while the rest is completely filled.

[0019] Furthermore, the existing tunnel has longitudinally arranged locking brackets at both ends of the transverse track bed, and the bottom of the cavity structure at both circumferential ends is supported by the top of the locking brackets.

[0020] Furthermore, along the circumferential direction of the tunnel, the upper inner side of both the male cavity and the female cavity has an arc surface.

[0021] On the other hand, a method for constructing a nestable cavity structure for lining reinforcement as described above is provided, characterized in that:

[0022] The method includes:

[0023] Prefabricated cavity units and rotatable T-keys, with the threaded screws of the rotatable T-keys welded to the outer side of the male cavity along the tunnel circumferential direction;

[0024] Along the tunnel circumference, a cavity unit is bonded and fixed to the inner side of the existing tunnel segment lining using epoxy grout, and a joint steel pipe is inserted into the male and square cavity ends of the cavity unit. Then, another cavity unit is placed on one side of the first cavity unit along the tunnel circumference, and the joint steel pipe is inserted into the male and square cavity of the other cavity unit accordingly. Next, the other cavity unit is bonded and fixed to the inner side of the existing tunnel segment lining using epoxy grout. The cavity units are spliced ​​into a ring in sequence, and the two sides of the cavity units arranged in a ring along the tunnel circumference are limited by locking brackets. Finally, the steel plate of the cavity unit is mechanically anchored to the existing tunnel segment lining using post-installed anchor bolts.

[0025] During the construction of the next ring, the threaded screw is inserted into the hollow internal thread groove and rotated. The rotatable T-key is inserted into the slot of the mother cavity of the next ring cavity unit. The rotating rod is rotated by rotating the handle, which drives the slotted bar to rotate until it is perpendicular to the slot. The hexagonal nut is then rotated to fix it in place. Finally, it is bonded to the inner side of the existing tunnel lining with epoxy grout. The rings are spliced ​​longitudinally, and the steel plate of the cavity unit is mechanically anchored to the existing tunnel lining with post-installed anchor bolts.

[0026] Cement mortar is poured into the male cavity and the square cavity through the pre-reserved opening on the cavity unit that is only supported by the locking bracket.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention provides a nestable cavity structure for lining reinforcement and its construction method. Based on the concept of "nested connection and adjustable stiffness," a novel cavity structure combining the advantages of conventional steel plate lining reinforcement and rectangular cavity reinforcement processes has been developed. It utilizes the reliability of conventional steel plate lining connected to existing tunnel lining structures via bolts and epoxy grout, while also fully leveraging the large circumferential stiffness of conventional cavity structures. This results in relatively low cost and improved integration with existing lining structures. Furthermore, the adjustable height of the cavity structure mitigates the drawback of conventional cavity structures having excessively large cross-sectional heights that are difficult to meet the clearance requirements of subway tunnels. The nested connection of male and female cavities enables continuous distribution along the tunnel's longitudinal direction, making it particularly suitable for reinforcing the circumferential joints of shield tunnel segments. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the internal lining reinforcement of shield tunnel segments provided in an embodiment of the present invention.

[0031] Figure 2 This is a cross-sectional view of the cavity structure provided in an embodiment of the present invention.

[0032] Figure 3 This is a planar unfolded view of the tunnel after the longitudinal adjacent cavities are nested and connected, as provided in the embodiment of the present invention.

[0033] Figure 4 This is a large-scale (three-dimensional) view of the mother cavity provided in an embodiment of the present invention.

[0034] Figure 5 This is a large-scale drawing of the rotatable T-key provided in an embodiment of the present invention.

[0035] Figure 6 This is a diagram showing the relationship between the rotatable T-key, the rotating handle, and the hexagonal nut provided in an embodiment of the present invention.

[0036] Figure 7 This is a cross-sectional view of the transverse connection between the male cavity and the female cavity provided in an embodiment of the present invention.

[0037] Figure 8 This is a schematic diagram of the connection between tunnel circumferential cavity units provided in an embodiment of the present invention.

[0038] Figure 9This is a cross-sectional view of the common cavity at the connection position of the tunnel circumferential cavity unit provided in an embodiment of the present invention.

[0039] Figure 10 This is a cross-sectional view of the square cavity at the connection position of the tunnel circumferential cavity unit provided in an embodiment of the present invention.

[0040] The diagram is labeled as follows:

[0041] 1-Segment lining, 2-Channel bed, 3-Track, 4-Tunnel centerline, 5-Cavity structure, 6-Anchor bracket, 7-Steel plate, 8-Square cavity, 9-Male cavity, 10-Female cavity, 11-Post-anchor bolt, 12-Rotable T-key, 13-Cement mortar, 14-Joint steel pipe;

[0042] 101 - Straight groove;

[0043] 121-Rotating rod, 122-Hollow internal threaded groove, 123-Threaded screw, 124-Rotating handle, 125-Hexagonal nut, 126-Circular washer, 127-Straight crossbar. Detailed Implementation

[0044] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0045] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "circumferential", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "setting," etc., should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] It should also be noted that although the order of steps is mentioned in the method description, in some cases, steps may be performed in a different order than that described here, and this should not be interpreted as a restriction on the order of steps.

[0048] In a specific implementation, the direction of the existing tunnel alignment is defined as "longitudinal," the direction perpendicular to it is defined as "lateral," the height direction of the segment lining (i.e., the direction perpendicular to the horizontal plane) is defined as "vertical," and the outline of the tunnel cross-section is defined as "circumferential." Furthermore, the area near the surrounding rock is defined as "outer side," and the area near the tunnel interior is defined as "inner side." Additionally, each component is defined as being closer to its center as the inner side and farther from its center as the outer side.

[0049] In underground engineering practice, with shield tunnel segment lining as a typical example, the process involves first casting and prefabricating reinforced concrete segment linings, followed by shield tunnel excavation and segment lining assembly. After the assembled segment linings gradually detach from the shield tail, grouting at the shield tail ensures close contact between the segment linings and the surrounding strata. However, segment linings constructed using this general method suffer from excessive strength but poor toughness, making it difficult to effectively cope with the complex and sensitive surrounding environment, the complex strata stresses in deep tunnels, and the vibrations and adverse effects of train operation within the tunnel. As operating time increases, various potential quality defects or problems gradually emerge, while existing lining reinforcement technologies are either uneconomical, inefficient, or lack durability.

[0050] To address this, the present invention provides a nestable cavity structure for lining reinforcement, which improves the reinforcement problem of shield tunnel segment lining and maximizes the service life of underground engineering projects.

[0051] Specifically, such as Figure 1 The cavity structure 5 is deployed inside the segment lining 1 of the existing tunnel. Its circumferential curvature is basically consistent with that of the tunnel lining being reinforced. It is composed of numerous cavity units spliced ​​together and fixed on the segment lining 1, spliced ​​circumferentially into a ring, and then longitudinally spliced ​​into a whole. It is symmetrically arranged circumferentially along the tunnel lining and continuously arranged along the cross-section of the tunnel lining. The track bed 2 in the existing tunnel is provided with longitudinally arranged locking brackets 6 at both ends of the transverse direction. The bottom of the cavity structure 5 at both ends of the circumferential direction is supported to the top of the locking brackets 6. The locking brackets 6 and the track 3 on the track bed 2 are symmetrically arranged along the tunnel centerline 4. The position of the locking brackets 6 should avoid the drainage ditches set on both sides of the tunnel.

[0052] like Figure 2The cavity unit includes a circumferentially bent steel plate 7, which unfolds into a rectangle. Post-installed anchor bolts 11 are installed on the steel plate 7. After the steel plate 7 is bonded to the inner side of the existing tunnel segment lining 1 with epoxy grout, it can be mechanically fixed to the segment lining 1 using the post-installed anchor bolts 11. Along the tunnel circumference, circumferential male cavities 9 and female cavities 10 are provided on both sides of the steel plate 7, both closed to the steel plate 7 and having circumferential through channels. Along the tunnel circumference, a circumferential square cavity 8 is also provided in the middle of the steel plate 7, which is closed to the steel plate 7 and has circumferential through channels. A typical cavity unit has at least two rows of post-installed anchor bolts 11, arranged between the male cavity 9 and the square cavity 8, and between the square cavity 8 and the female cavity 10. Of course, the number of post-installed anchor bolts 11 and their spacing along the tunnel circumference can be flexibly adjusted according to the situation. Generally, the circumferential spacing should not be less than 300mm, and the distance from the edge of the cavity unit should not be less than 100mm. The bottom width of the square cavity 8 is twice that of the male cavity 9 or the female cavity 10. The height of the male cavity 9 and the female cavity 10 is the same as that of the square cavity 8, and can be adjusted appropriately as needed. The specific height value can be flexibly adjusted within 50-100mm.

[0053] like Figure 7 Along the circumferential direction of the tunnel, a rotatable T-shaped key 12 is provided on the outer side of the male cavity 9, and a straight groove 101 is provided on the outer side of the female cavity 10. Along the longitudinal direction of the tunnel, when the cavity units are spliced, in two adjacent cavity units, the male cavity 9 of one cavity unit faces the female cavity 10 of the other cavity unit. The rotatable T-shaped key 12 of the male cavity 9 is inserted into the straight groove 101 of the female cavity 10 and rotated to form a nested connection structure, realizing longitudinal splicing.

[0054] like Figure 8 Along the tunnel circumference, when splicing the cavity units circumferentially, a joint steel pipe 14 is inserted between the male cavity 9 of two adjacent circumferential cavity units to achieve circumferential splicing. Additionally, a joint steel pipe 14 is also inserted between the square cavities 8 of two adjacent circumferential cavity units to further achieve circumferential splicing. For a 6m diameter subway tunnel, approximately 3-4 cavity units can generally be considered circumferentially (each length should be controlled to approximately 3m), and the splicing joints should avoid the longitudinal joints of the tunnel segment lining. The number of joint steel pipes 14 can be flexibly adjusted, with 2 inserted into the square cavity 8 and 1 inserted into the male cavity 9. The length of the connecting steel pipe 14 inserted into the cavity should not be less than 3 times the diameter of the steel pipe, and the length of the section inserted into the cavity's full cross-sectional height should not be less than 2 times the diameter of the steel pipe. Along the tunnel longitudinal direction, the positions of the connecting steel pipes 14 in each ring of cavity structure 5 should be staggered.

[0055] like Figure 5The rotatable T-key 12 includes a straight crossbar 127, to which a rotating rod 121 perpendicularly connected. The end of the rotating rod 121 has a hollow internally threaded groove 122 coaxial with it, into which a threaded screw 123 is inserted and rotatably connected. The end of the threaded screw 123 is vertically fixed to the longitudinal outer side of the male cavity 9. Furthermore, a rotating handle 124 is provided on the outer wall of the rotating rod 121. The outer wall of the rotating rod 121 between the rotating handle 124 and the straight crossbar 127 has external threads and is fitted with a circular washer 126 and a hexagonal nut 125. The diameters of the circular washer 126 and the hexagonal nut 125 are significantly larger than the opening width of the straight groove 101. During on-site installation, after the threaded screw 123 and the rotating rod 121 are connected, first align the direction of the horizontal bar 127 at the end of the rotatable T-key 12 with the direction of the horizontal groove 101 on the side of the mother cavity 10 and insert it. Then, rotate the rotating rod 121 90° using the rotating handle 124 to ensure that the horizontal bar 127 at the end of the rotatable T-key 12 is fully pressed against the mother cavity 10. At this time, the direction of the horizontal bar 127 should be as perpendicular as possible to the opening direction of the horizontal groove 101. Finally, tighten the hexagonal nut 125 and the circular washer 126. The rotatable T-keys 12 are evenly arranged along the tunnel circumference, and their spacing and number should correspond to the horizontal groove 101 on one side of the mother cavity 10. The number and position of the rotatable T-keys 12 have a certain correspondence with the post-installed anchor bolts 11, and generally, one T-key can be installed every two anchor bolts.

[0056] like Figure 4 On one side of the vertical edge of the mother cavity 10, there are regularly spaced I-shaped slots 101 at the middle height. The number and position of the slots correspond to the rotatable T-keys 12. The length of each slot can be considered as twice the length of the "-" at the end of the T-key, and its width can be considered as twice the thickness of the T-key. At the same time, the edge of the I-shaped slot 101 should not be less than 100mm from the edge of the mother cavity 10.

[0057] like Figure 9 The cavity 9 is filled with cement mortar 13, but only the upper half of the corresponding space in the insertion area of ​​the joint steel pipe 14 is filled. Correspondingly, the space requiring cement mortar filling is pre-separated from the space where the joint steel pipe 14 is inserted (e.g., by welding a partition). Injecting cement mortar 13 into the upper half of the cavity 9 increases circumferential stiffness. Figure 10The square cavity 8 is filled with cement mortar 13. Similarly, only the upper half of the corresponding space in the insertion area of ​​the joint steel pipe 14 is filled. Correspondingly, the space that needs to be filled with cement mortar and the space where the joint steel pipe 14 is inserted are pre-divided (e.g., by welding partitions). 3. The male cavity 9 and the square cavity 8 are variable cross-section cavities. The height of the end of the segmented cavity is half the height of the normal cavity. The length of the cavity height transition section should not be greater than one diameter of the joint steel pipe 14, and can be considered as 10cm. The length of the joint steel pipe 14 inserted into the normal height area of ​​the cavity should not be less than two diameters of the joint steel pipe 14, and can be considered as 20cm. Figure 9 The joint steel pipe 14 inserted into the male cavity 9 is the same as the joint steel pipe 14 inserted into the square cavity 8. The width of the square cavity 8 is twice that of the male cavity 9, and the height is the same. Cement mortar is only injected into the upper half of the cavity in the variable cross-section area, specifically micro-expansion cement mortar can be used.

[0058] like Figure 2 and Figure 7 Along the tunnel circumference, the upper inner sides of both the male cavity 9 and the female cavity 10 have curved surfaces, which can increase the overall bending stiffness of the cavities. The male cavity 9 and the female cavity 10 have the same dimensions and are set "back to back". The position of the rotatable T-key 12 must correspond to the position of the straight slot 101.

[0059] The aforementioned nestable cavity structure for lining reinforcement is a distributed cavity structure, avoiding the shortcomings of insufficient stiffness and insufficient reinforcement area of ​​conventional single cavities. It can form continuously distributed reinforcement areas along the tunnel longitudinal direction as needed, making it particularly suitable for reinforcing the circumferential joints of segment linings. It combines the reliability of conventional steel plate and lining structure anchor bolt connections, and can reduce the cavity height as needed to meet the requirements of subway tunnels, effectively improving the reinforcement quality of the lining structure. Under the dual effects of external additional loads and internal material performance degradation, various defects in existing underground engineering, especially tunnel linings, are becoming increasingly severe. The novel cavity structure of this invention combines the advantages of traditional steel plate reinforcement and conventional cavity reinforcement, better improving the overall reinforcement effect of tunnel linings.

[0060] like Figure 3 The construction method of the above-mentioned nestable cavity structure for lining reinforcement specifically includes the following steps:

[0061] S1: Based on the existing tunnel segment lining 1 reinforcement range and the number of cavity structure 5 segments along the tunnel circumference, divide the arc and arc length of each cavity unit, and use conventional reinforced concrete to pour the locking bracket 6 as required. One side of the locking bracket 6 is in line with the inner contour of the tunnel, and the other side adopts a rectangular contour and avoids the drainage ditches on both sides of the bottom of the tunnel.

[0062] S2: Prefabricated cavity unit and rotatable T-key 12, with the threaded screw 123 of the rotatable T-key 12 welded to the outside of the male cavity 9 (along the tunnel circumference). The cavity material is mainly thin steel, with composite fibers wrapped around the outside to increase toughness and durability. Specifically:

[0063] Cavity unit:

[0064] During factory prefabrication, taking into account the contours of the male cavity 9, female cavity 10, and square cavity 8, and based on the curvature requirements of the tunnel to be reinforced and the length division of the cavity units, various types of open-bottomed cavities are prefabricated in the factory using specific corrosion-resistant lightweight steel. Grooves are cut at required intervals on one side of the vertical edge of the female cavity 10, forming a straight groove 101. Threaded bolts 123 are welded to one side of the vertical edge of the male cavity 9, with the specific welding position corresponding to the straight groove 101. Then, according to the curvature requirements of the tunnel to be reinforced and the length division of the cavity units, corrosion-resistant lightweight steel plates are used to connect the male cavity 9, square cavity 8, and female cavity 10 into a complete cavity unit. Circular holes are pre-drilled on the steel plate 7 at required intervals to provide conditions for the subsequent anchor bolts 11. Finally, composite fiber material is used to wrap the surface of the steel. Furthermore, the circular washer 126 and the hexagonal nut 125 should be placed between the rotating handle 124 and the straight bar 127 in advance. At the same time, the hollow length of the hollow internal thread groove 122 should not be less than 1.2 times the thread length of the threaded screw 123. The threaded screw 123 is connected to the male cavity 9.

[0065] Rotatable T-key 12:

[0066] According to the structural requirements of the rotatable T-key 12, the following components are manufactured in the factory: a straight crossbar 127, a threaded screw 123, a rotating rod 121 with a hollow internal thread groove 122, a rotating handle 124, and a hexagonal nut 125. The circular washer 126 and the hexagonal nut 125 are placed between the rotating handle 124 and the "I" shape of the T-key. At the same time, it should be ensured that the "I" shape of the rotatable T-key 12 and the rotating handle 124 are basically aligned.

[0067] S3: Based on the specific positional relationship between the tunnel segment lining 1 to be reinforced and its internal track bed 2, track 3 and tunnel centerline 4, as well as the determined number and dimensions of the cavity units, scaffolding or a special platform vehicle will be erected to carry out the installation of the cavity units:

[0068] First, the bottom left locking bracket 6 is fixed to the top of the track bed 2 and the lining arch area with anchor bolts. During installation, the drainage ditches on both sides of the tunnel should be avoided.

[0069] Secondly, following the order from left to right along the tunnel ring, the segmented cavity units are gradually bonded and fixed to the existing tunnel lining with epoxy grout. The connecting steel pipes 14 between the cavity units should be inserted into the cavity end in time after the previous cavity unit is installed. Finally, the right locking bracket 6 is pressed against the cavity unit that has been installed to complete the installation and fixing of the entire ring cavity unit.

[0070] Then, the steel plate 7 of the cavity unit is mechanically anchored to the tunnel segment lining using the post-installed anchor bolts 11.

[0071] Finally, repeat the aforementioned steps to install and fix the adjacent ring cavity units in the longitudinal direction of the tunnel. If, according to design requirements, adjacent rings need to be connected as a single structural member for load-bearing, the following operations must be performed: Position the male cavity 9 of the subsequently installed cavity unit and the female cavity 10 of the already installed cavity unit "back-to-back," insert the rotatable T-key 12 into the slot 101 on the side of the already installed female cavity 10, then use the rotating handle 124 to press the T-key tightly against the side of the female cavity 10, and finally use the circular washer 126 and hexagonal nut 125 to completely fix the rotatable T-key 12 to the previous ring female cavity 10.

[0072] During the reinforcement of shield tunnel segment lining, the cavity units can be installed either from left to right or from right to left.

[0073] S4: According to the design requirements, grouting holes are reserved in the cavity near the locking bracket 6, and cement mortar 13 is injected into the male cavity 9 and the square cavity 10 to increase the circumferential stiffness of the wall.

[0074] In the structure of this invention, to ensure a tight fit between the entire ring cavity unit and the tunnel segment lining to be reinforced, when finally installing the right (or left) locking bracket 6, it may be necessary to drive steel wedges between the bracket and the cavity to increase the reliable connection between the cavity and the reinforced tunnel, depending on the situation. Simultaneously, when the cavity is bonded to the existing tunnel lining structure using epoxy grout, the epoxy grout thickness should be appropriately increased to adjust for the effects of steps or misalignments between the circumferential tunnel segments, i.e., adjusting the radius of curvature of the inner surface of the circumferential lining to better connect it to the cavity as a whole.

[0075] The core technology of this invention is a cavity unit composed of a square cavity 8, male and female cavities, and steel plate 7, which is adjustable in size, reliably connected, highly safe, and durable. On the one hand, it can meet the reinforcement needs of segment lining 1 under confined space conditions, and can form a continuous reinforcement area along the longitudinal direction of the tunnel as needed, achieving a true longitudinal nested continuous reinforcement effect. On the other hand, it can also effectively extend the service life of underground space structures, which is in line with the goal of environmentally friendly underground engineering construction.

[0076] In the structure of this invention, the cavity structure (including individual cavities and connecting steel plates) is mainly composed of steel and external composite fiber materials, or it can be entirely composed of composite fiber materials as needed. The cement mortar injected into the cavity should have micro-expansion characteristics to better fill the internal space of the cavity. The locking brackets 6 at the bottom on both sides are made of conventional reinforced concrete blocks. The rotatable T-key 12 and its auxiliary components (circular washer 126, hexagonal nut 125, rotating rod 121, rotating handle 124, and screw 123, etc.) should, as far as possible, be made of weathering steel with galvanized anti-corrosion coating.

[0077] The construction method provided by this invention requires the following precautions during implementation:

[0078] 1. The overall circumferential bending stiffness of the cavity unit is mainly determined based on the current status of the tunnel lining to be reinforced, the safety status, and the safety factor to be achieved after reinforcement. Generally speaking, the overall safety factor of the reinforced composite structure should not be less than 2.0.

[0079] 2. The number of circumferential segments and the arc length of each segment of the cavity unit should be determined in a coordinated manner according to the tunnel size and on-site installation needs. Generally speaking, the arc length of a single cavity unit should be controlled within 3-4m. The circumferential connection between cavity units is mainly completed by the connecting steel pipe 14 inserted at the end of the cavity. Therefore, the curvature and arc length of the connecting steel pipe 14 should be made in advance according to the design requirements, and the cavity area at the end of the cavity unit should be pushed into place on site.

[0080] 3. The connection between the cavity unit and the tunnel lining to be reinforced is a key factor in determining the reinforcement effect. Therefore, a combination of epoxy grout and anchor bolt fixing is adopted.

[0081] The structure of the present invention has the following features and advantages:

[0082] 1) Based on the concept of "nested connection and continuous arrangement", this invention can form a continuously arranged cavity reinforcement area in the longitudinal direction of the tunnel through the nested connection between male and female cavities, which can meet the reinforcement needs of various types of tunnel linings, especially for the reinforcement of the circumferential joint of shield tunnel segment lining.

[0083] 2) The concept of “flexible size and adjustable stiffness” proposed in this invention is mainly achieved by flexibly adjusting the height of the square cavity 8 and the male and female cavities according to the tunnel clearance conditions. At the same time, the horizontal distance between the square cavity 8 and the male and female cavities can also be flexibly adjusted according to the scope of the tunnel lining to be reinforced and the overall stiffness improvement requirements. Generally speaking, the width of a single new cavity 5 should be controlled at around 350mm, that is, to ensure that the horizontal net distance between the square cavity 8 and the male and female cavities of the new cavity 5 is ≥50mm.

[0084] 3) The cavity unit proposed in this invention should have long-term stability and durability. Therefore, it is advisable to attach or wrap composite fiber materials on the surface of the connecting steel plate 7 and each type of sub-cavity to form a composite structure with both rigidity and toughness. Alternatively, all of them can be considered as composite fiber materials as needed.

[0085] The "nested connection and continuous arrangement" method based on the "novel cavity" described in this invention has a clear concept, simple process, and convenient construction, and has high economic and social benefits. It has broad application prospects in tunnel engineering involving urban underground space development, rail transit, railway projects, etc.

[0086] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A nestable cavity structure for lining reinforcement, characterized in that: The cavity structure (5) is deployed inside the segment lining (1) of the existing tunnel and is composed of numerous cavity units spliced ​​together. The cavity unit includes a circumferentially bent steel plate (7) that unfolds into a rectangle. On both sides of the steel plate (7) are circumferential male cavities (9) and female cavities (10), which are closed with the steel plate (7) and have circumferential through channels. Along the circumferential direction of the tunnel, a rotatable T-shaped key (12) is provided on the outside of the male cavity (9), and a slot (101) is provided on the outside of the female cavity (10). When the cavity units are spliced ​​circumferentially, a joint steel pipe (14) is inserted between the male cavities (9) of two adjacent circumferential cavity units to achieve circumferential splicing; When the cavity units are spliced ​​longitudinally, in two longitudinally adjacent cavity units, the male cavity (9) of one cavity unit faces the female cavity (10) of the other cavity unit. The rotatable T-shaped key (12) of the male cavity (9) is inserted into the slot (101) of the female cavity (10) and rotated to achieve longitudinal splicing. A circumferential square cavity (8) is provided in the longitudinal center of the steel plate (7). The square cavity (8) is closed with the steel plate (7) and has a circumferential through channel. When the cavity units are spliced ​​circumferentially, a joint steel pipe (14) is inserted between the square cavities (8) of two adjacent cavity units in the circumferential direction to achieve circumferential splicing; The steel plate (7) is provided with a post-installed anchor bolt (11), and the steel plate (7) is fixed to the segment lining (1) by the post-installed anchor bolt (11); The rotatable T-key (12) includes a horizontal bar (127) with a rotating bar (121) perpendicular to it connected to the horizontal bar (127). The end of the rotating rod (121) is provided with a hollow internal threaded groove (122) coaxial with it. A threaded screw (123) is inserted into the hollow internal threaded groove (122). The end of the threaded screw (123) is vertically fixed to the longitudinal outer side of the male cavity (9).

2. The nestable cavity structure for lining reinforcement according to claim 1, characterized in that: The outer wall of the rotating rod (121) is provided with a rotating handle (124). The outer wall of the rotating rod (121) between the rotating handle (124) and the straight bar (127) is provided with an external thread, and a circular washer (126) and a hexagonal nut (125) are installed.

3. The nestable cavity structure for lining reinforcement according to claim 2, characterized in that: The cavity (9) is filled with cement mortar (13), and only the upper half of the joint steel pipe (14) is filled in the insertion area, while the rest is completely filled.

4. The nestable cavity structure for lining reinforcement according to claim 3, characterized in that: The square cavity (8) is filled with cement mortar (13), and only the upper half of the joint steel pipe (14) is filled in the insertion area, while the rest is completely filled.

5. The nestable cavity structure for lining reinforcement according to claim 4, characterized in that: The existing tunnel's track bed (2) has longitudinally arranged locking brackets (6) at both transverse ends, and the bottom of the cavity structure (5) at both circumferential ends is supported to the top of the locking brackets (6).

6. The nestable cavity structure for lining reinforcement according to claim 5, characterized in that: Along the tunnel circumference, the upper inner side of both the male cavity (9) and the female cavity (10) has an arc surface.

7. The method for constructing a nestable cavity structure for lining reinforcement as described in claim 6, characterized in that: The method includes: Prefabricated cavity unit and rotatable T-key (12), the threaded screw (123) of the rotatable T-key (12) is welded to the outside of the male cavity (9) along the tunnel circumferential direction; In the tunnel circumference, a cavity unit is bonded and fixed to the inner side of the existing tunnel segment lining (1) with epoxy grout, and a joint steel pipe (14) is inserted into the end of the male cavity (9) and the square cavity (8) of the cavity unit; then another cavity unit is placed on one side of the first cavity unit along the tunnel circumference, and the joint steel pipe (14) is inserted into the male cavity (9) and the square cavity (8) of the other cavity unit respectively. Then another cavity unit is bonded and fixed to the inner side of the existing tunnel segment lining (1) with epoxy grout; they are spliced ​​into a ring in sequence, and the cavity units arranged in a ring along the tunnel circumference are limited on both sides by locking brackets (6). Finally, the steel plate (7) of the cavity unit is mechanically anchored to the existing tunnel segment lining (1) by the rear anchor bolt (11). During the construction of the next ring, the threaded screw (123) is inserted into the hollow internal thread groove (122) and rotated. The rotatable T-key (12) is inserted into the slot (101) of the mother cavity (10) of the next ring cavity unit. The rotating rod (121) is rotated by rotating the handle (124), which drives the horizontal bar (127) to rotate to be perpendicular to the slot (101). The hexagonal nut (125) is rotated to fix it. Then, it is fixed to the inner side of the existing tunnel segment lining (1) by epoxy grouting. Each ring is spliced ​​longitudinally, and the steel plate (7) of the cavity unit is mechanically anchored to the existing tunnel segment lining (1) by the post-installed anchor bolt (11). Cement mortar (13) is poured into the male cavity (9) and the square cavity (8) through the pre-reserved opening on the cavity unit that is only supported by the locking leg (6).

Images