Large-span underground cavern top arch layer excavation method and supporting structure

Abstract

The invention provides a large-span underground cavern top arch layer excavation method and a supporting structure, and relates to the technical field of building construction.The large-span underground cavern top arch layer excavation method mainly comprises the steps that a top arch layer is divided into eight subareas to be reasonably excavated in sequence, supporting is conducted through a supporting component, and the supporting component comprises a storage frame and a long-strip-shaped bag body; the storage rack is arranged at the position needing to be supported in the steps S1 to S8, a storage cavity used for containing the long-strip-shaped bag body is formed in the storage rack, and the two ends of the long-strip-shaped bag body are fixedly connected to the bottom wall of the storage cavity and the storage rack correspondingly; the driving part is used for driving the long-strip-shaped bag body to gradually expand along the target supporting side wall to form an annular structure so as to support the side wall. Compared with the prior art, the method has the advantage that the structural stability and the construction safety of the large-span underground cavern in the excavation process are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and particularly to a method for excavating the crown arch layer of a large-span underground cavern and a support structure therefor. Background Art

[0002] At present, the excavation of large underground caverns at home and abroad generally adopts the method of "central pilot tunnel + secondary excavation", that is, first excavate the central pilot tunnel, and then carry out the excavation of both sides to finally form the designed contour. This construction method is relatively mature in the excavation of medium and small-span caverns, and the construction risks are controllable. However, with the improvement of engineering requirements, the number of large-span underground caverns is gradually increasing, and the traditional "central pilot tunnel + secondary excavation" method has obvious limitations in such projects.

[0003] Specifically, when the span of the cavern exceeds a certain degree, the excavation width of both the left and right sides increases significantly, making it difficult for the surrounding rock to form a complete "arch effect" in the initial stage of excavation, resulting in uneven stress on the crown arch layer, a significant increase in the risk of structural deformation, and even potential safety hazards such as cavern collapse. Summary of the Invention

[0004] In order to improve the structural stability and construction safety of large-span underground caverns during excavation, the present application provides a method for excavating the crown arch layer of a large-span underground cavern and a support structure therefor.

[0005] In a first aspect, the present application provides a method for excavating the crown arch layer of a large-span underground cavern, adopting the following technical solutions: A method for excavating the crown arch layer of a large-span underground cavern, comprising the following construction steps: S1: Divide the crown arch layer into eight zones for sequential excavation and support. The eight zones include: The first zone, located in the middle area of the upper left part of the cavern; The second zone, located in the upper right part of the cavern, symmetrically arranged with the first zone; The third zone, located on the left side of the cavern, adjacent to the first zone; The fourth zone, located on the right side of the cavern, symmetrically arranged with the third zone; The fifth zone, located below the third zone, with the same width as the third zone; The sixth zone, located below the fourth zone; The seventh zone, being the crown arch central pilot tunnel area, arranged in the upper middle part of the cavern; The eighth zone, located in the lower middle area of the cavern; S2: According to a preset excavation route, excavate and carry out initial support on the first zone. When the excavation and support reach a predetermined depth, stop the construction of the first zone; S3: Excavate and conduct initial support for the second area and the third area in sequence according to a preset route. Among them, the second area starts construction after the construction of the first area is suspended, and the third area is excavated simultaneously with or at intervals from the second area; S4: After the excavation and support of the second area reach a predetermined distance, start the excavation and support of the fourth area; S5: After the excavation and support depths of the third area and the fourth area both exceed the construction depths of the first area and the second area, conduct the excavation and support of the fifth area and the sixth area respectively until the design depth is reached; S6: Conduct the excavation and support of the middle pilot tunnel area, i.e., the seventh area. During the construction process, carry out crown deformation monitoring synchronously, and use the settlement monitoring device to obtain the crown deformation data in real time; S7: When the excavation and support depth of the seventh area reaches the corresponding excavation and support depth of the first area, conduct the excavation and support of the eighth area, and its excavation and support depth is not greater than the corresponding depth of the seventh area; S8: Repeat steps S1 to S7 and push forward layer by layer until the overall crown layer reaches the design depth.

[0006] Preferably, the widths of the first area and the second area are both not greater than 1 / 6 of the total width of the cavern; and / or, the widths of the third area and the fourth area are both not greater than 1 / 6 of the total width of the cavern; and / or, the width of the seventh area is not greater than 1 / 5 of the total width of the cavern.

[0007] Preferably, in steps S2 and S3, at least after the excavation and initial support of 30 meters are completed in the first area, then excavate and conduct initial support for the second area and the third area in sequence according to the preset route.

[0008] Preferably, in steps S3 and S4, during the excavation and support of the second area, along the direction of the preset excavation route, excavate a plurality of connecting pilot tunnels connected to the first area and the second area at intervals in the seventh area; Among them, the spacing between adjacent connecting pilot tunnels is not less than 5 meters, the bottom of the connecting pilot tunnels is flush with the bottom of the first area and the second area, and a support arch structure space is reserved between the top of the connecting pilot tunnels and the crown of the cavern.

[0009] In the second aspect, the present application provides a support structure for the excavation method of the crown layer of a large-span underground cavern, and adopts the following technical solutions: A support structure for the excavation method of the crown layer of a large-span underground cavern, which is applicable to the excavation method of the crown layer of a large-span underground cavern described in the above technical solution, includes a support member and a driving member, wherein: The support member includes a storage rack and a long strip-shaped bladder. The storage rack is arranged at the position to be supported in steps S1 to S8, and a storage cavity for accommodating the long strip-shaped bladder is provided inside it. Two ends of the long strip-shaped bladder are respectively fixedly connected to the bottom wall of the storage cavity and the storage rack; The driving member is used to drive the long strip-shaped bladder to gradually expand along the side wall of the target support and form an annular structure to realize the support for the side wall.

[0010] Preferably, the body of the long strip-shaped bladder has a water bladder cavity and an air bladder cavity along its length direction. The water bladder cavity is at least partially located outside the long strip-shaped bladder, and the air bladder cavity is covered inside the water bladder cavity.

[0011] Preferably, a plurality of support stay ropes are arranged at intervals along the length direction inside the cavity of at least one of the water bladder cavity and the air bladder cavity; And / or, a plurality of diaphragm flaps are arranged at intervals along the length direction inside the cavity of at least one of the water bladder cavity and the air bladder cavity, and flow openings are formed on the diaphragm flaps.

[0012] Preferably, a plurality of hanging rings are fixedly arranged on the side wall of the long strip-shaped bladder along its length direction, and hooks that are hooked with the hanging rings are fixedly arranged on the storage rack.

[0013] Preferably, a plurality of reinforcing strip plates are embedded at intervals along the length direction on the outer side wall of the long strip-shaped bladder.

[0014] Preferably, the support structure further includes a telescopic rod that can be telescoped and locked in length. Protruding columns are arranged on at least part of the reinforcing strip plates, and column grooves that are inserted and matched with the protruding columns are arranged at both ends of the telescopic rod; And / or, the support structure further includes a support frame that is arranged on the ground of the cavern. A through groove for the long strip-shaped bladder to pass through is formed on the support frame, and the size of the through groove is not larger than the outer diameter size of the long strip-shaped bladder in the expanded state.

[0015] The present invention has the following advantages and beneficial effects: (1) By dividing the top arch layer into eight zones and excavating and supporting them in a specific order, the present invention has multiple beneficial effects: Among them, the seventh zone (the middle pilot tunnel area) and the eighth zone (the area below the middle part) are arranged to be constructed in the last stage, which is beneficial to retaining the middle rock pillar in the initial stage of construction, thereby forming an effective support for the top arch structure, significantly improving the overall stability and construction safety of the cavern structure; In addition, the zoning method combined with a reasonable construction sequence effectively controls the scale of the free face exposed by a single excavation, reduces the risk of surrounding rock instability, and also provides sufficient space for equipment operation and support operation, ensuring the orderly progress and quality control of the construction process; (2) During the excavation and support process in the second area of the present invention, a plurality of connecting pilot tunnels are excavated at intervals in the seventh area to connect the first area and the second area, which has multiple beneficial effects: on the one hand, this connecting structure helps to realize the synchronous or intermittent construction of the first area and the second area, improving the flexibility and efficiency of construction organization; on the other hand, the connecting pilot tunnels, as temporary passages, facilitate the transfer of excavation slag and resource allocation, effectively enhancing the overall smoothness of construction; in addition, a support arch structure space is reserved between the top of the connecting pilot tunnels and the crown arch, which not only provides an operating space for the subsequent arch support structure but also plays a role in temporarily supporting and stabilizing the surrounding rock during the construction process, further enhancing the structural safety and controllability; at the same time, this method of excavating the pilot tunnels in stages also saves time for the subsequent construction of the seventh area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic structural diagram showing eight partitions.

[0018] Figure 2 It is a schematic structural diagram showing the connecting pilot tunnels and the support members supported in the first area.

[0019] Figure 3 is Figure 2 an enlarged view of part A in

[0020] Figure 4 It is a schematic structural diagram showing the support members and the driving members.

[0021] Figure 5 It is a schematic structural diagram showing the storage rack.

[0022] Figure 6 It is a schematic internal sectional view showing the long strip bladder.

[0023] Figure 7 It is a schematic diagram showing the connection relationship between the reinforcing strip plates and the protruding columns.

[0024] Figure 8 It is a schematic structural diagram showing the support frame.

[0025] Figure 9 It is a schematic structural diagram showing the telescopic rod.

[0026] Figure 10It is a schematic structural diagram designed to show the inflation of the long strip bladder and its simultaneous support in the first and third zones.

[0027] The markings in the figure are as follows: 1. Chamber; 11. First zone; 12. Second zone; 13. Third zone; 14. Fourth zone; 15. Fifth zone; 16. Sixth zone; 17. Seventh zone; 171. Connecting guide tunnel; 1711. Support arch structure space; 18. Eighth zone; 2. Support component; 21. Storage rack; 211. Storage cavity; 212. Hook; 213. Anchor rod; 22. Long strip bladder; 221. Water bladder cavity; 222. Air bladder cavity; 3. Driving component; 31. Water pipe; 32. Air pipe; 4. Support pull rope; 5. Diaphragm flap; 51. Circulation port; 6. Hanging ring; 7. Reinforcing strip plate; 71. Protruding column; 8. Telescopic rod; 81. Column groove; 9. Support frame; 91. Through groove. Detailed implementation mode

[0028] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts fall within the scope protected by the present invention.

[0029] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are usually of the same type, and the number of objects is not limited. For example, the first object can be one or multiple. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally indicates an "or" relationship between the associated objects before and after.

[0030] The following combines Figures 1 to 10 A large-span underground chamber crown excavation method and a support structure provided by an embodiment of this application are described in detail through specific embodiments and their application scenarios.

[0031] Embodiment 1: A large-span underground chamber crown excavation method includes the following construction steps: S1: Divide the crown into eight zones for sequential excavation and support. The eight zones specifically include: The first zone 11, located in the middle area of the upper left part of the chamber 1, is preferentially constructed to provide initial lateral stability; The second area 12 is located in the upper right part of the chamber 1 and is symmetrically arranged with the first area 11. It forms a bilateral stable structure in combination with the construction of the first area 11. The third area 13 is located on the left side of the chamber 1, adjacent to the first area 11, and can extend downward to form a unified working face with the subsequent fifth area 15. The fourth area 14 is located on the right side of the chamber 1 and is symmetrically arranged with the third area 13. The fifth area 15 is located below the third area 13 and has the same width as the third area 13. It can be reserved as an equipment platform or a transportation passage. The sixth area 16 is located below the fourth area 14. The seventh area 17 is the top arch pilot tunnel area, which is arranged in the upper middle part of the chamber 1 and is used for the formation of the subsequent middle rock pillar. The eighth area 18 is located in the area below the middle of the chamber 1 and is the last excavation area.

[0032] S2: Excavate and conduct initial support for the first area 11 according to the preset excavation route. The excavation equipment can be a hydraulic rock drilling jumbo, a crawler excavator or a tunnel boring machine. Of course, in other embodiments, a shotcrete + systematic bolt 213 support + steel arch frame combined structure can be selected, and a metal mesh or arch foot locking bolts 213 can be added if necessary. When the excavation and support reach the predetermined depth, suspend the construction of the first area 11 and wait for the subsequent areas to be advanced coordinately.

[0033] S3: Sequentially excavate and conduct initial support for the second area 12 and the third area 13 according to the preset route. Among them, the second area 12 starts construction after the first area 11 is suspended. The third area 13 can be constructed simultaneously with the second area 12 or with a slight interval. When constructing the third area 13, a temporary ramp or transportation passage to the fifth area 15 should be set up to ensure the passage of construction machinery and the smooth transfer of muck, and improve the overall construction efficiency.

[0034] S4: After the second area 12 completes the excavation and support for the predetermined distance, start the construction of the fourth area 14. To improve the space utilization rate, a reinforced concrete temporary platform or an arch foot working platform can be set up between the fourth area 14 and the sixth area 16 to ensure operation safety and facilitate material stacking and equipment dispatching.

[0035] S5: After the excavation and support depths of the third area 13 and the fourth area 14 both exceed the construction depths of the first area 11 and the second area 12, respectively conduct the excavation and support for the fifth area 15 and the sixth area 16 until the design depth is reached. The fifth area 15 and the sixth area 16 are preferably excavated and controlled in layers using the bench method or the middle pilot tunnel method. In some embodiments, the support method can be selected as the initial arch plus systematic bolt 213 combined with the reserved interface structure of the secondary lining.

[0036] S6: Excavation and support of the middle pilot tunnel area, i.e., the seventh area 17, are carried out. Construction is preferably carried out in segments along the tunnel axis direction, and the interval pilot tunnel method or the sectional tunneling method can be adopted. During the construction process, crown deformation monitoring is carried out simultaneously to dynamically master the displacement, settlement, and stress changes generated by the structure during excavation, ensuring construction safety and surrounding rock stability. The deformation monitoring adopts a combination of distributed point layout and real-time acquisition. The main monitoring objects include: the deformation displacement and settlement volume at the crown, arch waist, and the positions of the two side wall feet of the crown arch. The following equipment can be selected according to the actual situation of the project and the requirements of monitoring accuracy: Full-automatic multi-point laser settlement monitoring system: Reflective targets can be arranged at multiple key positions such as the crown, arch shoulders, and side walls of the cavern 1. The elevation changes of each measuring point are collected in real time through a laser rangefinder to achieve high-precision monitoring of the structure settlement trend. This system has functions such as automatic calibration, error compensation, and wireless data transmission, and is suitable for long-term layout.

[0037] Fiber Bragg grating displacement sensor (FBG): It is arranged in the steel arch frame of the support structure, the shotcrete surface, or the surrounding rock. By monitoring the change of the fiber optic wavelength, it can sense small deformation amounts and can achieve millimeter-level displacement monitoring. It is especially suitable for continuous monitoring of areas sensitive to surrounding rock deformation, with a fast response speed and strong anti-electromagnetic interference ability.

[0038] In addition, the monitoring system is equipped with a data acquisition terminal, a remote transmission module, and a data analysis platform to realize functions such as real-time data upload, automatic early warning, and visual curve analysis. It can give an early warning in time before the crown arch shows an abnormal deformation trend, assisting the construction unit to adjust the excavation rhythm and support parameters.

[0039] S7: When the excavation and support depth of the seventh area 17 reaches the corresponding depth of the first area 11, the excavation and support of the eighth area 18 are carried out. The excavation and support depth of the eighth area 18 is not greater than the corresponding depth of the seventh area 17. The short bench excavation method is preferably adopted to avoid disturbing the structure of the seventh area 17 that has not been consolidated and stabilized, and at the same time, part of the rock pillar is retained to play a temporary support role, further improving the excavation safety.

[0040] S8: Repeat steps S1 to S7, advancing layer by layer from top to bottom, and finally realizing the safe, stable, and sequential excavation and support of the entire crown arch layer, ensuring the mechanical stability of the structure and the controllability of the construction rhythm.

[0041] In this way, the seventh area 17 and the eighth area 18 are constructed last, which can form the purpose of supporting by the middle rock pillar and ensure the construction safety.

[0042] As an optional implementation method, to achieve a reasonable division of the construction sections and fully guarantee the structural stability, it is preferable to limit the width of each section within a reasonable proportion range. Specifically: The widths of the first area 11 and the second area 12 are both preferably not greater than 1 / 6 of the total width of the cavern 1, so as to ensure that the excavation face width in the upper left and right arch shoulder areas is moderate, and avoid the instability of the surrounding rock caused by an overly wide one-time excavation face.

[0043] The widths of the third area 13 and the fourth area 14 are also both preferably not greater than 1 / 6 of the total width of the cavern 1, so as to form a symmetric and stable structural relationship with the upper excavation area, taking into account the structural stiffness and the space reservation, which is beneficial to the organization and reservation of the support spaces in the later fifth area 15 and sixth area 16.

[0044] As the top arch middle pilot tunnel area, the seventh area 17 preferably has a width not greater than 1 / 5 of the total width of the cavern 1, so as to control the disturbance degree of the middle pilot tunnel excavation to the surrounding rock on both sides and the arch top structure, and ensure the support strength of the cavern 1. At the same time, it takes into account the sufficient width of the construction passage and the material transportation passage.

[0045] Preferably, in steps S2 and S3, in order to improve the stability of the step-by-step support of the structure and reduce the construction interference between adjacent operation areas, it is preferred to first complete the partial excavation and initial support of the first area 11, and then advance the construction of the second area 12 and the third area 13.

[0046] Specifically, it is preferred that after the excavation and initial support of a length of not less than 30 meters are completed in the first area 11, the excavation and initial support operations of the second area 12 and the third area 13 are carried out in sequence. This construction sequence helps to form an arch section structure with support stiffness in the front in advance, provides stable support for the excavation of the subsequent sections, and at the same time facilitates the adjustment and optimization of the support parameters in combination with the early monitoring results. Of course, the specific excavation depth of the first area 11 can also be reasonably adjusted according to the on-site geological conditions and the stability of the surrounding rock.

[0047] Furthermore, preferably, between steps S3 and S4, in order to improve the construction coordination efficiency between the middle part and the two side sections of the top arch structure, reduce the material transportation distance, and ensure the stable transition between structures, the following method can be adopted: during the excavation and support of the second area 12, along the preset excavation route direction, a plurality of connecting pilot tunnels 171 connected to the first area 11 and the second area 12 are excavated at intervals in the seventh area 17. These connecting pilot tunnels 171 can form a pressure relief and transportation passage between the two side arch sections in terms of structure, and can be used as an auxiliary path for personnel, equipment and muck removal in terms of construction organization, effectively improving the overall construction efficiency. Among them, the structural parameters of the connecting pilot tunnels 171 are preferably as follows: 1. The horizontal distance between adjacent connecting pilot tunnels 171 is not less than 5 meters, so as to avoid excessively weakening the continuous arch bearing capacity of the seventh area 17, and at the same time reserve enough space for support closure; 2. The bottom of the connecting adit 171 is flush with the bottoms of the first area 11 and the second area 12 to ensure the slope rationality and operation convenience during passage, slag discharge, and equipment cross - area transfer; 3. A certain supporting arch structure space 1711 is reserved between the top of the connecting adit 171 and the crown arch of the cavern 1. Preferably, the reserved space height is not less than 0.8 meters, which is used for arranging steel arch frames, steel bar meshes, or temporary arch support structures during subsequent construction to maintain the overall stiffness of the arch and reduce the disturbance of adit construction to the main arch structure.

[0048] Embodiment 2: The present application also provides a support structure for the excavation method of the crown arch layer of a large - span underground cavern 1. This support structure is mainly applied to the support operations in each stage during the above - mentioned crown arch layer sectional and sequential excavation construction process, aiming to improve the support efficiency, enhance adaptability, and reduce the construction labor intensity. The support structure mainly includes a support component 2 and a driving component 3, where: Referring to Figures 2 - 4 As shown, the support component 2 includes a storage rack 21 and a long strip bladder 22. The storage rack 21 is installed at the positions that need initial or temporary support in steps S1 to S8. It is a long strip - shaped frame structure with a longitudinal storage cavity 211 inside, which is used to accommodate and restrict the expansion of the long strip bladder 22. The two ends of the long strip bladder 22 are respectively fixedly connected to the bottom wall of the storage cavity 211 and the outside of the storage rack 21 to ensure uniform stress and avoid displacement.

[0049] Preferably, for the convenience of moving and arranging the storage rack 21 on the construction site, installation handles for easy grasping can be provided on both sides of it. The installation handles can be metal rings or rubber - coated handles to improve the handling comfort and operation safety.

[0050] The long strip bladder 22 is made of a composite rubber material or a polymer synthetic material with wear - resistance, good flexibility, and high - strength compressive performance to adapt to the complex underground cavern 1 environment and improve the service life. The long strip bladder 22 has the ability of controllable inflation and pressure release, and its internal air pressure is adjusted by the driving component 3 to flexibly change its volume and shape at different construction stages.

[0051] Referring to Figure 10 As shown, since the long strip bladder 22 can adaptively deform within the cross - section of the cavern 1 and can fit the crown arch structures of various shapes, it greatly improves the fitting degree between the support structure and the surrounding rock, thereby improving the support stability. Compared with traditional support methods such as steel supports or scaffolding erection, this structure does not require frequent replacement of the support length or manual assembly, effectively reducing the manual labor intensity and time consumption during the construction process.

[0052] Furthermore, after the long strip bladder 22 is inflated under the action of the driving component 3, an annular support surface can be formed inside the chamber 1. This support surface conforms to the cross-sectional structure of the chamber 1 and covers the top of the chamber 1 and the arch foot areas on both sides, thereby realizing the effective support for the entire cross-section of the chamber 1. This annular support can not only bear the radial pressure from the surrounding rock, but also relieve the additional load brought by the deformation of the surrounding rock during the excavation process, improving the stability of the surrounding rock.

[0053] After the excavation of some tunnel sections is completed, the driving component 3 can continue to control the injection of compressed gas or liquid into the long strip bladder 22 to further expand the volume of the bladder, so as to adapt to the geometric changes of the newly formed excavation space, thereby realizing the self-adaptive extension of the support surface. This self-adaptive expansion ability ensures the continuity and integrity of the support structure during the whole process of crown arch construction, avoids the problem of support gaps caused by construction progress, and improves the safety and construction efficiency of the overall structure.

[0054] As an optional embodiment, when fixing the fixed storage rack 21, the way of inserting the anchor bolt 213 into the ground of the chamber 1 for anchoring can be selected. The anchor bolt 213 can be an expansion anchor bolt 213, a self-tapping anchor bolt 213 or a chemical anchor bolt to ensure that the storage rack 21 is stably and reliably positioned at the predetermined position during the inflation process of the bladder, preventing displacement or overturning.

[0055] Of course, other fixing methods can also be selected according to the construction site conditions and rock formation structures, such as positioning the storage rack 21 by means of wedge support feet support method, lateral reinforcement member pressing method, or combined with bolt frame locking structure on the construction platform, etc., which has good engineering adaptability and versatility.

[0056] Refer to Figure 6 and Figure 7 As shown, the bladder body of the long strip bladder 22 has a water bladder cavity 221 and an air bladder cavity 222 along its length direction, where: The water bladder cavity 221 is arranged on the outer side of the long strip bladder 22 and at least partially surrounds the outer periphery of the air bladder cavity 222; The air bladder cavity 222 is located inside the water bladder cavity 221 and covers its middle area, forming a nested composite structure.

[0057] The material of the water bladder cavity 221 is preferably a rigid elastomer material or a high-strength composite film material with shear resistance. Its design purpose is to inhibit the deformation degree and provide stable and continuous support strength after filling with liquid. Compared with a single air bladder structure, this composite layout form has both fast response and high-strength support capabilities.

[0058] Specifically, the filling medium in the water sac cavity 221 is liquid water or other media that are not easily compressible (such as glycerol solution, polymer hydrogel, compressed latex, etc.), so as to ensure that the support structure does not undergo obvious deformation during the pressure-bearing process. Due to the weight and incompressibility of the liquid itself, its main role in the support process is to form a support "hard core", significantly enhancing the overall bearing capacity and stability of the structure.

[0059] The air sac cavity 222 coated on the inner side is made of a light and flexible expandable material, preferably high-ductility rubber or multi-layer thermoplastic elastomeric film, and has a rapid inflation response ability. During use, after the air sac cavity 222 expands, it can quickly support the sac body structure, preferably fit the curved surfaces at the top and both sides of the cavern 1, quickly establish an initial support force, and then form a closed ring structure to perform a wrapped and fitting support on the surrounding rock.

[0060] The driving component 3 is used to drive the long strip sac body 22 to expand and fit along a predetermined support path, and specifically includes the following two functional modules: 1. Hydraulic driving module: It includes components such as a water pump, a water pipe 31, and connectors. One end of the water pipe 31 is connected to the water pump, and the other end is connected to the water injection port of the water sac cavity 221. The water pump is supplied with water from an external water source and injects liquid into the water sac cavity 221, gradually pressurizing to form a support force.

[0061] 2. Pneumatic driving module: It includes an air pump, an air pipe 32, and a pressure regulating valve. The air pump is connected to the air sac cavity 222 through the air pipe 32 and can achieve efficient inflation, enabling the air sac cavity 222 to expand rapidly to support the structure shape.

[0062] In actual operation, it is preferably to first turn on the air pump to inflate the air sac cavity 222, quickly expand the sac body into shape, and fit the cavern wall to form a preliminary support; then inject liquid into the water sac cavity 221 through the water pump to form a stable structural support core. This order of operation can take into account both rapid response and long-term stability, significantly improving the support efficiency and bearing capacity.

[0063] Of course, in other alternative embodiments, the water sac cavity 221 can also be filled with other high-density, non-compressible liquid or gel media, such as bentonite slurry, silicone oil, high-viscosity mineral oil, etc., to adapt to the different requirements for support stiffness and flexibility under different geological conditions.

[0064] Through the application of the above water-air composite support system, the support structure has both good initial deformation fitting ability and high-strength and long-lasting stable support effect during the top arch excavation process, and can adapt to the different support requirements of different sections in large-span and multi-stage construction.

[0065] Inside the chamber of at least one of the water sac chamber 221 and the air sac chamber 222, a plurality of support drawstrings 4 are arranged at intervals along the length direction thereof. Both ends of the support drawstring 4 are fixed to the inner wall of the sac chamber, which is used to limit the radial expansion amplitude of the cavity, keep the cross-sectional shape of the sac stable after inflation, and avoid irregular phenomena such as bulging and deformation, so as to further improve the uniformity of the support force and the structural safety.

[0066] As an alternative implementation, a number of diaphragm flaps 5 can also be arranged at intervals along the length direction or the width direction inside the chamber of the water sac chamber 221 and / or the air sac chamber 222. A separation structure is formed between each diaphragm flap 5 and the inner wall of the chamber, and a communication flow port 51 is provided on the diaphragm flap 5, which is used to realize the slow and uniform flow and diffusion of the liquid or gas in the cavity. This structure has a positive effect on preventing local overpressure and improving the uniformity of the internal medium distribution, and helps to improve the support performance and the sac shape control ability.

[0067] Preferably, in order to facilitate adjusting the support length and precisely controlling the range of the long strip sac 22 unfolding from the storage cavity 211, a plurality of hanging rings 6 are fixedly installed at intervals along the length direction of the side wall of the long strip sac 22. Each hanging ring 6 is in a ring shape, C shape or hook ring shape structure, and can be made of metal material or high-strength plastic material to ensure the strength and durability for long-term use. The number and spacing of the hanging rings 6 can be configured according to the size requirements of different excavation sections of the cavern 1. For example, a hanging ring 6 is installed at an interval of every 10 cm, so as to achieve more precise adjustment and control.

[0068] Correspondingly, a hook 212 assembly matching with the hanging ring 6 is installed on the external or internal structure of the storage rack 21. The hook 212 can be an elastic lock type, a rotary hook type or a slot plug-in type structure, which ensures stable hooking and quick release during actual use and adapts to the operation requirements in complex field environments. By matching and reconstructing the positions of the hook 212 and the hanging ring 6, the effective length of the long strip sac 22 extending from the storage cavity 211 can be flexibly controlled, avoiding the problem that the unfolding length of the sac exceeds the support area, causing structural interference or material waste, and at the same time preventing the problem that the extending length is insufficient resulting in incomplete support coverage.

[0069] Furthermore, in order to enhance the structural strength and anti-deformation ability of the long strip sac 22 in the inflated state, a plurality of reinforcing strip plates 7 are embedded at intervals along the length direction of the outer side wall of the long strip sac 22. The reinforcing strip plates 7 are preferably made of composite material plates, high-performance engineering plastic plates or glass fiber reinforced plates with light weight, high strength and good flexibility. The reinforcing strip plates 7 play a role of longitudinal shape limitation and out-of-plane support during the inflation process of the sac, effectively suppressing local buckling and collapse phenomena, and further improving the overall load-bearing capacity and support stability of the sac.

[0070] Refer to Figure 2 andFigure 9 As shown, the support structure further includes a telescopic rod 8 assembly, which is used to further enhance the circumferential support capacity of the long strip bladder 22. Especially in areas where the cross-section of the chamber 1 is relatively large or the surrounding rock stability is poor, it helps to improve the support stiffness and safety redundancy of the overall structure. The installation quantity of the telescopic rod 8 assembly can be set according to requirements.

[0071] The telescopic rod 8 preferably adopts a multi-section structure design to improve its transportation convenience and on-site adjustment flexibility. Each telescopic rod 8 can include two or more rod bodies, which are connected in the following ways: 1. Threaded connection: The rod bodies of each section are connected by internal and external thread screwing. After screwing tightly, they can be reliably positioned, which is convenient for adjustment and provides a certain shear strength. 2. Pin-limited connection: A plurality of through holes are arranged at intervals along the length direction of the rod body, and positioning and locking are achieved through pins to realize segmented telescoping and stable fixation. 3. Embedded snap structure: Elastic beads or elastic pieces are arranged inside the rod body, which are automatically snapped into the positioning holes of the target section, and the operation is convenient.

[0072] After the telescopic rod 8 is telescoped to the target length, column grooves 81 are opened at both ends thereof. The column grooves 81 are used for plug-in cooperation with the protruding column 71 structures on the outer side of the long strip bladder 22, so as to construct a stable connection system. The protruding column 71 is preferably arranged on some of the reinforcing strip plates 7, and its material can be aluminum alloy, carbon fiber composite material, high-strength plastic, etc., with the performance advantages of both light weight and strength. The plug-in structure between the column groove 81 and the protruding column 71 can adopt a tight fit form or be provided with a stop snap structure to ensure the anti-slip performance and operation stability after connection.

[0073] In order to avoid the protruding column 71 interfering with the overall covering state of the long strip bladder 22, a recessed part is provided on the structure of the long strip bladder 22 corresponding to the protruding column 71. The recess can be an annular or elliptical groove, so that the long strip bladder 22 can fit and cover the outer shape of the protruding column 71 in the inflated state, effectively eliminating the local protrusion problem, and at the same time avoiding stress concentration caused by structural discontinuity during the inflation process, and improving the overall strength and support uniformity of the bladder.

[0074] In addition, when the long strip bladder 22 covers the protruding column 71 structure, it can also play a secondary strengthening role: on the one hand, the protruding column 71 and the reinforcing strip plate 7 are integrated through physical wrapping, improving the longitudinal stability of the bladder; on the other hand, when the bladder expands, a reverse wrapping force is applied to the protruding column 71, which helps to further limit its displacement and achieve active restraint.

[0075] As an alternative embodiment, the support structure further includes a support frame 9 installed on the ground of the cavern 1, and this support frame 9 is used to further stabilize the posture of the long strip bladder 22 during the initial inflation and long-term support stages, preventing unstable states such as slippage, deflection or torsion during the support process.

[0076] The support frame 9 is of a frame structure, and a through groove 91 is provided at its bottom. The through groove 91 extends longitudinally along the support frame 9, and the cross-sectional shape of the through groove 91 matches the outer shape of the long strip bladder 22 to conform to the natural bending form of the bladder. The size of the through groove 91 is set to be slightly smaller than the maximum outer diameter size of the long strip bladder 22 in the fully inflated state. This structural design enables the long strip bladder 22 to be limited and covered by the through groove 91 after the inflation process, thereby effectively suppressing its lateral displacement, rolling or swinging, and improving the stability and anti-disturbance ability of the support system.

[0077] To further improve the trafficability and safety at the construction site, the two ends of the support frame 9 are preferably set as inclined bevel structures, and the inclination angle is set according to the traffic standards of construction vehicles or pedestrians in the cavern 1 (such as within the range of 15° to 30°), so as to facilitate vehicle passage and reduce the risk of pedestrians tripping, and avoid forming steps or obstacles due to height differences.

[0078] It should be noted that in this article, the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitations, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the reverse order according to the functions involved. For example, the described method may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, the features described with reference to certain examples may be combined in other examples.

[0079] The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A method for excavating the crown arch layer of a large-span underground chamber, characterized in that, It includes the following construction steps: S1: Divide the top arch layer into eight zones for sequential excavation and support. The eight zones include: The first zone (11), located in the middle area of the upper left part of the cavern (1); The second zone (12), located in the upper right part of the cavern (1), symmetrically arranged with the first zone (11); The third zone (13), located on the left side of the cavern (1), adjacent to the first zone (11); The fourth zone (14), located on the right side of the cavern (1), symmetrically arranged with the third zone (13); The fifth zone (15), located below the third zone (13), with the same width as the third zone (13); The sixth zone (16), located below the fourth zone (14); The seventh zone (17), which is the middle pilot tunnel area of the top arch, arranged in the upper middle part of the cavern (1); The eighth zone (18), located in the lower middle area of the cavern (1); S2: According to the preset excavation route, excavate and conduct initial support for the first zone (11). When the excavation and support reach the predetermined depth, stop the construction of the first zone (11); S3: Sequentially excavate and conduct initial support for the second zone (12) and the third zone (13) according to the preset route. Among them, the second zone (12) starts construction after the construction of the first zone (11) pauses, and the third zone (13) is excavated simultaneously with or at intervals from the second zone (12); S4: After the second zone (12) completes excavation and support for a predetermined distance, start the excavation and support of the fourth zone (14); S5: After the excavation and support depths of the third zone (13) and the fourth zone (14) both exceed the construction depths of the first zone (11) and the second zone (12), respectively conduct the excavation and support of the fifth zone (15) and the sixth zone (16) until the design depth is reached; S6: Conduct the excavation and support of the middle pilot tunnel area, that is, the seventh zone (17). During the construction process, simultaneously carry out top arch deformation monitoring, and use the settlement monitoring device to obtain the top arch deformation data in real time; S7: When the excavation and support depth of the seventh zone (17) reaches the corresponding excavation and support depth of the first zone (11), conduct the excavation and support of the eighth zone (18), and its excavation and support depth is not greater than the corresponding depth of the seventh zone (17); S8: Repeat steps S1 to S7, advancing layer by layer until the entire top arch layer reaches the design depth.

2. The method for excavating the crown arch layer of a large-span underground cavern according to claim 1, characterized in that The widths of both the first zone (11) and the second zone (12) are not greater than 1 / 6 of the total width of the cavern (1); And / or, the widths of both the third zone (13) and the fourth zone (14) are not greater than 1 / 6 of the total width of the cavern (1); And / or, the width of the seventh zone (17) is not greater than 1 / 5 of the total width of the cavern (1).

3. The support structure of the large-span underground chamber crown excavation method according to claim 1, characterized in that, In steps S2 and S3, at least after the first zone (11) completes 30 meters of excavation and initial support, then sequentially conduct excavation and initial support for the second zone (12) and the third zone (13) according to the preset route.

4. The support structure of the large-span underground cavern crown excavation method according to claim 1, characterized in that, In steps S3 and S4, during the process of excavating and supporting the second zone (12), along the preset excavation route direction, excavate multiple connecting pilot tunnels (171) in the seventh zone (17) that are connected to the first zone (11) and the second zone (12) at intervals; Among them, the distance between adjacent said connecting pilot tunnels (171) is not less than 5 meters. The bottom of the connecting pilot tunnel (171) is flush with the bottoms of the first area (11) and the second area (12), and a support arch structure space (1711) is reserved between the top of the connecting pilot tunnel (171) and the crown of the chamber (1).

5. A support structure for the excavation method of the top arch layer of a large-span underground cavern, applicable to the excavation method of the top arch layer of a large-span underground cavern according to any one of claims 1-4, characterized in that, It includes a support component (2) and a driving component (3), where: The support component (2) includes a storage rack (21) and a long strip bladder (22). The storage rack (21) is arranged at the position to be supported in steps S1 to S8, and a storage cavity (211) for accommodating the long strip bladder (22) is provided inside it. The two ends of the long strip bladder (22) are respectively fixedly connected to the bottom wall of the storage cavity (211) and the storage rack (21); The driving component (3) is used to drive the long strip bladder (22) to gradually expand along the target support side wall and form an annular structure to realize the support for this side wall.

6. The support structure of the large-span underground chamber crown excavation method according to claim 5, characterized in that, The body of the long strip bladder (22) has a water bladder cavity (221) and an air bladder cavity (222) along its length direction. The water bladder cavity (221) is at least partially located outside the long strip bladder (22), and the air bladder cavity (222) is wrapped inside the water bladder cavity (221).

7. The support structure of the large-span underground chamber crown excavation method according to claim 6, characterized in that, At least one of the water bladder cavity (221) and the air bladder cavity (222) is internally provided with a plurality of support stay ropes (4) arranged at intervals along the length direction; And / or, at least one of the water bladder cavity (221) and the air bladder cavity (222) is internally provided with a plurality of diaphragm flaps (5) arranged at intervals along the length direction. A flow port (51) is provided on the diaphragm flap (5).

8. The support structure of the large-span underground chamber crown excavation method according to claim 5, characterized in that, A plurality of hanging rings (6) are fixedly arranged on the side wall of the long strip bladder (22) along the length direction, and hooks (212) hooked to the hanging rings (6) are fixedly arranged on the storage rack (21).

9. The support structure of the large-span underground chamber crown excavation method according to claim 5, characterized in that A plurality of reinforcing strip plates (7) are embedded at intervals along the length direction on the outer side wall of the long strip bladder (22).

10. The support structure of the large-span underground chamber crown excavation method according to claim 9, characterized in that, The support structure further includes a telescopic rod (8) that can be telescoped and locked in length. At least some of the reinforcing strip plates (7) are provided with protruding columns (71), and column grooves (81) inserted and matched with the protruding columns (71) are provided at both ends of the telescopic rod (8); And / or, the support structure further includes a support frame (9). The support frame (9) is arranged on the ground of the chamber (1), and a through groove (91) for the long strip bladder (22) to pass through is provided on the support frame (9). The size of the through groove (91) is not larger than the outer diameter size of the long strip bladder (22) in the expanded state.

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