Construction method of a tunnel with a rescue station provided with a semi-transverse smoke extraction ventilation system

Abstract

The present application relates to the technical field of tunnel engineering, and particularly relates to a construction method of a tunnel with a rescue station provided with a semi-transverse smoke exhaust ventilation system, which comprises the following steps: continuously constructing a primary support of a main tunnel; jump-forming secondary lining in a rescue station section, only strengthening the primary support at a predetermined opening and suspending the secondary lining, and temporarily supporting the secondary lining by a lining trolley; subsequently constructing an auxiliary tunnel and an upper network; finally breaking the primary support at the opening, mechanically cutting and excavating an outer passage and a smoke exhaust shaft, and connecting the outer passage and the smoke exhaust shaft with a transverse and longitudinal smoke exhaust passage. The present application significantly shortens the construction period, reduces the opening risk and cost, and ensures the structural safety and waterproofness through parallel construction of the main tunnel and the auxiliary tunnel, jump-forming primary support instead of secondary lining, mechanical cutting to break the primary support, and opposite excavation of the shaft.

Description

Technical Field

[0001] This invention belongs to the field of tunnel engineering technology, and specifically relates to a construction method for a tunnel with a semi-lateral smoke exhaust ventilation system in a rescue station. This invention optimizes the three-dimensional layout and construction organization of the smoke exhaust channels in long tunnels for rescue stations, achieving crisscrossing construction to improve construction coordination, and ultimately enhancing the safety and economy of tunnel construction. Background Technology

[0002] In recent years, with rapid economic development and the booming construction of various infrastructure projects, the number of high-altitude extra-long tunnels has also increased significantly. Ventilation technology and emergency rescue plans have become key technical challenges in the construction of these tunnels. Compared to ordinary tunnels, the long distance and enclosed environment of extra-long tunnels make fire risk a core safety risk in rescue operations. When a fire occurs inside a tunnel, the ability to quickly and effectively remove smoke, ensuring the safe evacuation of personnel and the unobstructed flow of rescue routes, is crucial to the design of a tunnel disaster prevention and rescue system.

[0003] Existing ventilation and smoke extraction methods for extra-long tunnels mainly fall into three categories: longitudinal ventilation, full transverse ventilation, and semi-transverse ventilation. Longitudinal ventilation uses jet fans to push smoke along the tunnel's longitudinal direction; the system is simple but the smoke extraction path is long, making it suitable for short tunnels. Full transverse ventilation involves setting up air supply and exhaust ducts along the entire length of the tunnel, providing good smoke extraction but with high civil engineering costs, making it suitable for urban road tunnels. Semi-transverse ventilation only involves exhaust ducts, through which smoke is centrally discharged; it represents a compromise between smoke extraction effectiveness and construction costs.

[0004] In long railway tunnels requiring emergency rescue stations, current technology employs a design that combines diaphragms with ventilation and smoke extraction ducts, along with the construction of the rescue station. This often necessitates the arrangement of numerous auxiliary tunnels, such as transverse passages, smoke extraction ducts, vertical shafts, and inclined shafts, above or to the side of the main tunnel. Existing solutions primarily focus on ventilation and smoke extraction during operation, lacking comprehensive consideration for the overall construction organization of the main tunnel and auxiliary tunnels during the construction phase. In tunnel sections with rescue stations, numerous auxiliary tunnels, such as transverse passages, smoke extraction ducts, vertical shafts, and inclined shafts, are often required above or to the side of the main tunnel. If a single working face is used for sequential construction, completing the entire main tunnel first and then constructing the remaining auxiliary tunnels, it will significantly extend the construction period and substantially increase construction costs.

[0005] On the other hand, in terms of construction technology, the secondary lining of the main tunnel in existing technologies usually requires continuous construction and one-time molding to ensure the integrity and waterproof performance of the lining structure. If a flue opening is reserved during construction, it is often necessary to open the opening by mechanical demolition or blasting after the secondary lining is constructed. This is not only difficult and inefficient, but also prone to damaging the existing lining structure, affecting the safety and service life of the tunnel structure.

[0006] The inventors' team filed Chinese invention patent application CN117027902A in 2023, disclosing a smoke exhaust and ventilation structure for an emergency rescue station in a railway tunnel. This structure improves smoke exhaust efficiency by optimizing the structure of the emergency rescue station and smoke exhaust channels, preventing fresh air from mixing with smoke and affecting fresh air quality, and utilizing inclined shafts to achieve independent smoke exhaust and ventilation. However, it lacks specific guidance for rapid construction in emergency rescue operations.

[0007] Therefore, how to optimize the construction organization of the main tunnel and auxiliary tunnels in long tunnels with rescue stations, and improve construction efficiency and reduce construction costs while ensuring structural safety, has become an urgent technical problem to be solved. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem that the construction of long tunnels with rescue stations in the prior art is too long and too costly due to the sequential construction of the main tunnel and a large number of auxiliary tunnels. The invention provides a construction method for tunnels with rescue stations equipped with semi-lateral smoke exhaust ventilation systems.

[0009] The present invention achieves the above objectives through the following technical solutions:

[0010] A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station, the smoke exhaust ventilation system comprising an upper network and smoke exhaust shafts, the upper network comprising interconnected longitudinal smoke exhaust channels and transverse smoke exhaust channels; the construction method includes the following steps: Step S1: Construct the main tunnel and continuously build the initial support along the entire length of the main tunnel.

[0011] Step S2: Within the length of the main tunnel where the rescue station is located, secondary lining is constructed longitudinally along the tunnel using a skip-formwork method, wherein: At the location where the flue gas duct opening is to be opened, a reinforced primary support structure is constructed. This primary support structure remains intact and is not opened for the time being, but the secondary lining pouring of this section is skipped, so that this section is supported solely by the primary support. At locations where no flue opening is planned, the initial support and secondary lining are constructed sequentially according to standard procedures. Step S3: After the initial support construction position of the main tunnel exceeds the starting position of the rescue station by 200-350 meters, construction begins on the auxiliary tunnels and the upper network of the smoke exhaust and ventilation system within the rescue station section. The auxiliary tunnels include a left pilot tunnel and a right pilot tunnel.

[0012] Step S4: After the upper network of the smoke exhaust ventilation system is in place, at the location where the smoke exhaust duct opening is to be opened in step S2, the initial support of the main tunnel is broken; during the breaking, the sprayed concrete layer is cut along the outline using mechanical cutting and the steel frame support is cut off in sections, and the external passage of the initial support is formed by excavating outward from the side of the main tunnel; then the smoke exhaust shaft is excavated vertically upward, so that the smoke exhaust shaft is connected to the horizontal smoke exhaust duct that has been completed above, and connected to the vertical smoke exhaust duct through the horizontal smoke exhaust duct.

[0013] The longitudinal smoke exhaust channel is formed by excavating along the longitudinal direction of the main tunnel from the sidewall of the inclined shaft, while the transverse smoke exhaust channel is formed by excavating horizontally from the longitudinal smoke exhaust channel toward the main tunnel.

[0014] The construction method of this invention adopts staggered construction. By starting the construction of the auxiliary tunnel after the initial support construction of the main tunnel exceeds the boundary of the rescue station section, the main tunnel and the auxiliary tunnel are constructed in parallel or staggered manner. Compared with the traditional sequential construction method, the construction period is significantly shortened. The skip-formwork method is used to avoid pouring the secondary lining at the opening of the flue, and only the initial support needs to be removed later, avoiding the difficulty and high risk of removing the reinforced concrete secondary lining.

[0015] This invention combines the initial support not being opened with precise demolition. Before the upper network of the smoke exhaust channel is in place, the initial support remains intact and unopened, fully utilizing its load-bearing capacity to maintain the stability of the surrounding rock. Later, mechanical cutting is used to precisely demolish the initial support, avoiding damage to the already constructed secondary lining from blasting vibrations, thus ensuring structural integrity and waterproofing.

[0016] The location where the smoke exhaust duct opening is planned refers to the side wall location where the smoke exhaust duct needs to be opened on the side of the main tunnel in the design.

[0017] Furthermore, at least part of the smoke exhaust shafts are formed by excavating downwards from the bottom of the horizontal smoke exhaust duct. The smoke exhaust shafts are excavated in opposite directions, from downwards from the horizontal smoke exhaust duct and upwards from the initial support passage, which improves connectivity efficiency and speeds up construction.

[0018] Furthermore, in step S4, the smoke exhaust shaft adopts a counter-excavation method, including: excavating downwards from the bottom of the transverse smoke exhaust channel to form the upper section of the smoke exhaust shaft; excavating upwards from the end of the initial support outer channel to form the lower section of the smoke exhaust shaft; after the upper and lower sections of the smoke exhaust shaft are connected, a locking ring beam is installed at the connection point. The locking ring beam can effectively reinforce the connection joint and ensure structural stability.

[0019] Furthermore, in step S2, at the predetermined location of the flue gas duct opening, the initial support structure adopts a reinforced design, including: increasing the spacing of the steel frame supports to 0.6m–0.8m per frame, and / or, increasing the thickness of the shotcrete to 20cm–30cm. The reinforced initial support structure uses a design that increases the thickness by 30%–100% compared to conventional initial supports, and the steel frame specifications can be increased by one level to improve the support strength of the initial support. This ensures that the skipped section has sufficient load-bearing capacity even without secondary lining for co-support, ensuring construction safety.

[0020] Furthermore, a transition section is provided between the reinforced initial support structure and the conventional initial support structure. Within this transition section, the spacing of the steel frame supports gradually transitions from the conventional spacing to a denser spacing. This effectively avoids abrupt changes in the stiffness of the initial support structure and prevents stress concentration and deformation cracking at the interface between the reinforced and conventional sections.

[0021] Furthermore, in step S2, the longitudinal length of the section skipping the secondary lining is 4m to 8m. This length is greater than the longitudinal dimension of the transverse smoke exhaust duct inlet, ensuring sufficient operating space for the construction of the smoke exhaust duct opening, and subsequently matching the excavation of the initial support external passage and the smoke exhaust shaft, thereby matching the smoke exhaust shaft and the transverse smoke exhaust duct.

[0022] Furthermore, in step S2, the lining trolley is moved to the section where the secondary lining is skipped and parked there. The curved steel formwork of the lining trolley provides temporary mechanical support and construction protection for the initial support. Parking the lining trolley in the skipped section and using its curved steel formwork to provide temporary support and protection for the initial support effectively prevents deformation and damage to the initial support in the skipped section under long-term lack of secondary lining support, achieving multiple uses for one machine and simplifying the construction process. Through the coordinated use of skipped formwork construction and lining trolley protection, damage and deformation of the initial support structure are reduced.

[0023] Furthermore, in step S3, when the initial support construction position of the main tunnel passes the rescue station by 200 to 350 meters, the main tunnel continues to advance forward, and at the same time, the construction of the auxiliary tunnel and the upper network of the smoke exhaust and ventilation system in the rescue station section is started, so as to realize the parallel operation of the main tunnel and the auxiliary tunnel.

[0024] Furthermore, the distance between the working faces of the main tunnel and the auxiliary tunnels shall not be less than 30m. This ensures that blasting and excavation do not interfere with each other, while simultaneously achieving a spatially staggered and temporally parallel construction organization.

[0025] Furthermore, in step S2, when constructing secondary lining at locations where no flue opening is predetermined, waterstops are pre-installed at the construction joints at both ends. For sections where secondary lining is skipped, waterstops are pre-installed at the construction joints of the secondary lining at both ends, forming a continuous waterstop structure when the initial support passage is excavated.

[0026] Furthermore, in step S2, when constructing the secondary lining (hereinafter referred to as "secondary lining") at locations where no pre-determined flue opening is planned, pre-embedded connecting bars are installed at both ends of the secondary lining. For sections where the secondary lining is skipped, pre-embedded connecting bars, such as L-shaped or U-shaped connecting bars, are installed at the construction joints of the secondary lining at both ends. One end of the connecting bar is pre-embedded in the secondary lining, and the other end is subsequently bent and anchored into the opening structure of the subsequently poured primary support external passage. This improves structural continuity and waterproof sealing, preventing leakage at later joints.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The construction method provided by this invention, through the interwoven construction organization of the main tunnel and auxiliary tunnels, allows for the immediate commencement of construction of the auxiliary tunnels and the upper network of the smoke exhaust and ventilation system after the initial support construction of the main tunnel extends 200-350 meters beyond the boundary of the rescue station section. While the main tunnel continues to advance, the auxiliary tunnels are constructed simultaneously, avoiding the extended overall construction period caused by the traditional sequential construction mode of main tunnel first, followed by auxiliary tunnels. In the GQ Tunnel No. 3 inclined shaft construction area, this method simultaneously completed the construction of the auxiliary tunnels while the main tunnel construction was underway, significantly shortening the construction period.

[0028] 2. The tunnel construction method of this invention employs a skip-formwork approach, constructing only the reinforced initial support structure at the predetermined location for the smoke exhaust duct opening, thus skipping the secondary lining pouring. Later, only the initial support needs to be removed to open the tunnel, avoiding the difficulties and high risks associated with opening into the high-strength, densely reinforced concrete secondary lining. The reinforced initial support (steel frame spacing increased to 0.6–0.8 m / frame, shotcrete thickness 20–30 cm) can independently bear the surrounding rock load, ensuring construction safety in the skipped section during the period of secondary lining absence.

[0029] 3. In the tunnel construction method of this invention, before the upper network of the smoke exhaust duct is constructed and in place, the initial support remains intact and closed, making full use of its bearing capacity to maintain the stability of the surrounding rock. After the upper network is constructed, the initial support is precisely broken along the outline using mechanical cutting, avoiding damage to the already constructed secondary lining and waterproof layer caused by blasting vibrations, and ensuring the integrity of the structure and the waterproof sealing. After breaking, the external channel of the initial support is excavated in opposite directions to the smoke exhaust shaft to achieve efficient connection.

[0030] 4. The construction method of this invention employs a counter-excavation approach for the smoke exhaust shaft. Specifically, the upper section is excavated downwards from the bottom of the transverse smoke exhaust channel, while the lower section is excavated upwards from the end of the initial support outer channel. After the upper and lower sections are connected, a locking ring beam is installed for reinforcement. This method significantly improves connectivity efficiency, shortens the shaft construction cycle, and ensures a stable joint structure.

[0031] 5. Through reasonable construction organization, the present invention allows for parallel operation of the main tunnel and auxiliary tunnels, and the personnel configuration can be 1.2 to 1.5 times that of the conventional configuration of the main tunnel. The number of personnel and machinery for auxiliary tunnel construction is only 1 / 4 to 1 / 2 of that for the main tunnel, thus avoiding idle resources and waste and effectively reducing construction costs. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the smoke exhaust and ventilation tunnel system for the rescue station according to Embodiment 1 of the present invention.

[0033] Figure 2 This is an enlarged schematic diagram of the smoke exhaust channel connection node in Embodiment 1 of the present invention.

[0034] Figure 3 This is a schematic diagram of the cross-section of the main hole in Embodiment 1 of the present invention.

[0035] Figure 4 This is a schematic diagram of the overall structure of the smoke exhaust and ventilation tunnel system for the rescue station according to Embodiment 1 of the present invention.

[0036] Figure 5 This is a partial cross-sectional schematic diagram of the connection between the tunnel main shaft, the smoke exhaust shaft, and the transverse smoke exhaust channel in Embodiment 1 of the present invention.

[0037] Figure 6 This is a schematic diagram of the steel mesh construction layout.

[0038] Marked in the image: 1-Main tunnel, 2-Rescue station section, 3-Inclined shaft, 4-Smoke exhaust shaft, 4a-Upper section of smoke exhaust shaft, 4b-Lower section of smoke exhaust shaft, 4c-Initial support external passage, 5-Longitudinal smoke exhaust passage, 6-Transverse smoke exhaust passage, 7-Auxiliary tunnel, 8-Left side pilot tunnel, 9-Right side pilot tunnel, 101-Initial support, 102-Secondary lining. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0040] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0041] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0042] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0043] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0044] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0045] Example 1 This embodiment uses the rescue station at the No. 3 inclined shaft of the GQ Tunnel as an example to describe the invention in detail. Figure 4 The diagram shows the overall structure of the smoke exhaust and ventilation tunnel system for the rescue station. The GQ tunnel is a double-track railway tunnel with a total length exceeding 22km. According to the disaster prevention and rescue design, an emergency rescue station is located at the intersection of the No. 3 inclined shaft and the tunnel. The rescue station starts at mileage DK394+850 and ends at mileage DK396+530, with a total length exceeding 1.6km. The rescue station adopts a semi-lateral smoke exhaust and ventilation system, with an evacuation pilot tunnel on each side of the tunnel, the centerline of which is 45m from the left centerline of the main tunnel. The rescue station section includes a smoke exhaust and ventilation system and auxiliary tunnels. The smoke exhaust and ventilation system includes longitudinal smoke exhaust channels, transverse smoke exhaust channels, and smoke exhaust shafts. The auxiliary tunnels include a left pilot tunnel, a right pilot tunnel, air supply ducts, and air supply shafts, among others.

[0046] This embodiment utilizes innovative construction methods to efficiently and safely complete the construction of the main tunnel and the aforementioned auxiliary tunnels.

[0047] First, such as Figure 1 As shown in the diagram, this schematic illustrates the spatial arrangement of the tunnel main tunnel, the rescue station section, and the semi-lateral smoke exhaust ventilation system. The semi-lateral smoke exhaust ventilation system of the rescue station in this embodiment includes the following core components: tunnel main tunnel 1, rescue station section 2, inclined shaft 3, and the semi-lateral smoke exhaust ventilation system.

[0048] Tunnel 1 is the main tunnel of the railway tunnel, with a cross-sectional dimension of 14m in width and 11m in height.

[0049] Rescue station section 2 is located inside the main tunnel and includes two pilot tunnels on both sides, namely the left pilot tunnel 8 and the right pilot tunnel 9. The main tunnel 1 is connected to the left and right pilot tunnels 8 and 9 by multiple evacuation cross passages.

[0050] The semi-horizontal smoke exhaust ventilation system includes: The longitudinal smoke exhaust passage 5 is formed by excavating the side of the inclined shaft 3 parallel to the main tunnel. One end of the longitudinal smoke exhaust passage 5 is connected to the lower half of the cross-section of the No. 3 inclined shaft, and the other end extends longitudinally along the rescue station section 2. The longitudinal smoke exhaust passage 5 is above the main tunnel 1.

[0051] Transverse smoke exhaust duct 6: Installed longitudinally at intervals along the rescue station section, each transverse smoke exhaust duct has a cross-sectional dimension of 5.0m × 4.75m (longitudinal × height). The transverse smoke exhaust duct 6 is located above the main tunnel opening, extending one end to the top of the far side arch of the main tunnel opening, and the other end connecting to the longitudinal smoke exhaust duct 5. The end of the transverse smoke exhaust duct 6 furthest from the longitudinal smoke exhaust duct 5 connects downwards to the main tunnel opening 1 via smoke exhaust shaft 4. The transverse smoke exhaust duct is equipped with an electrically operated damper, which can be remotely opened by the control system in case of fire.

[0052] Smoke exhaust shaft 4: Multiple shafts are located at intervals on the left and right sides of the main tunnel 1 of section 2 of the rescue station. Each smoke exhaust shaft has a cross-sectional dimension of 4.0m × 5.0m (width × height). Figure 5 As shown, the lower end of the smoke exhaust shaft 4 is connected to the main tunnel 1, and the upper end is connected to the corresponding transverse smoke exhaust channel 3.

[0053] Inclined shaft 3: such as Figure 1 As shown, Shaft No. 3 is a construction shaft. A ventilation duct baffle is installed inside the shaft, dividing the shaft's cross-section into an upper air supply duct and a lower smoke exhaust duct. The longitudinal smoke exhaust duct 5 connects to the lower half of the shaft's cross-section, and the flue gas is ultimately discharged outside the tunnel through the lower half of the shaft's cross-section.

[0054] The inclined shaft enters the main tunnel construction section using the "small pilot tunnel climbing method," excavating uphill to the main tunnel arch elevation. After excavating a certain distance to create working space, the main tunnel is excavated in reverse, with temporary support expanded to achieve the standard construction cross-section of the main tunnel. Construction at other auxiliary tunnel intersections employs the bench method and full-face method. Excavation methods are selected based on the surrounding rock conditions, using either weak blasting or controlled blasting. The layout of blast holes is based on the cross-sectional shape of the intersection, employing a combination of long and short drill bits to strictly control over-excavation at the intersections.

[0055] When constructing the intersection of the inclined shaft and the main tunnel, before excavation reaches the designed outline, the principle of early support and early closure should be followed, employing temporary support measures of "advanced small guide pipes + steel frame and steel mesh + anchor bolts + shotcrete" for closure. When the surrounding rock at the intersection is relatively good, temporary steel support may not be necessary. When the design support level of the intersection is Class III and there is no steel arch frame, steel arch frames should be added within 2-3 meters before and after the intersection to enhance the stability of the load-bearing structure.

[0056] This embodiment describes a construction method for a tunnel equipped with a semi-lateral smoke exhaust ventilation system at a rescue station. The core of this method lies in using techniques such as skip-formwork construction and temporarily not opening the initial support to achieve parallel operation of the main tunnel and auxiliary tunnels, significantly shortening the construction period. Specifically, it includes the following steps: Step S1: Continuous construction of the initial support of the main tunnel, and simultaneous commencement of auxiliary tunnel construction.

[0057] The main tunnel 1 was excavated using either the full-face method or the bench method. After excavation, the initial support 101 was constructed immediately. The initial support 101 employed conventional techniques, including the erection of steel frame supports (I16, I18, and I22a steel frames) at intervals of 0.8-1.2m per frame, laying of reinforcing mesh, and spraying C25 concrete to a design thickness of 12-30cm. The arrangement of the reinforcing mesh during construction is as follows... Figure 6 As shown in Tables 1 and 2, the specific construction steel frame, lining type, and excavation method are as follows.

[0058] Table 1: Statistics on Lining Types of the Main Tunnel Section of the Rescue Station

[0059] During the initial support construction, shotcrete was applied using a wet shotcrete machine. The application was carried out in a segmented, sectional, S-shaped sequence from bottom to top. The initial shotcrete thickness was controlled at 3-4 cm, and the thickness of each subsequent shotcrete application was no more than 10 cm for the arch crown and no more than 15 cm for the sidewalls. When there were significant depressions in the rock surface, leveling was performed during the initial shotcrete application. For areas where secondary lining was not to be applied, shotcrete was repeatedly applied to increase the thickness until the design thickness was reached.

[0060] For wet shotcrete, the thickness of the sprayed concrete can be controlled using the embedded nail method. Longitudinal connecting bars can be added to the existing steel frame, connecting reinforcement, or embedded nails to control the smoothness of the shotcrete. Wet shotcrete should be sprayed in layers, sections, and segments, following a bottom-up, first-fill-then-sweep sequence. Each segment should not exceed 6m in length. Spraying routes should preferably employ reciprocating spraying, up-and-down spraying, S-shaped spraying, or spiral spraying, and can be followed according to the spraying route diagram.

[0061] Two hours after the final setting of the shotcrete, water curing should be carried out promptly, and the curing time should not be less than 7 days. Vehicle-mounted fog cannons or water spraying can be used for curing.

[0062] Table 2: Support Parameters for the Main Tunnel of the Rescue Station

[0063] Note: Eight self-propelled anchor bolts were added to the sidewall.

[0064] When the initial support construction position of the main tunnel 1 extends approximately 300 meters beyond the boundary of rescue station section 2, construction of all auxiliary tunnels and the longitudinal smoke exhaust channel 5 and transverse smoke exhaust channel 6 above the smoke exhaust and ventilation system within rescue station section 2 is rapidly initiated. At this time, the main tunnel 1 continues to advance, while the auxiliary tunnels are constructed simultaneously in the area behind which stable initial support has been achieved, forming a parallel operation pattern with multiple points and surfaces in the rear. The distance between the tunnel face and the auxiliary tunnel faces is strictly controlled to be more than 30 meters to ensure that blasting excavation does not interfere with each other.

[0065] Step S2: Secondary lining construction using formwork.

[0066] During the construction of the secondary lining in section 2 of the rescue station, a skip-formwork method was adopted, as detailed below: (1) Location of unplanned flue opening: Following standard procedures, after the waterproof layer is laid, reinforced concrete secondary lining 102 is continuously poured section by section using a lining trolley, such as Figure 3 As shown.

[0067] (2) The location where the exhaust duct opening is to be opened is to skip the section.

[0068] This section was reinforced during the initial support stage. As shown in Table 2, the spacing of the steel frame supports was increased from the conventional 1.2m / frame to 0.6m / frame, and the thickness of the shotcrete was increased to 30cm. The reinforced initial support can independently bear the surrounding rock load, ensuring construction safety during the period without secondary lining to cooperate with the load.

[0069] Next, a waterproof layer is laid, with the waterproof membrane continuously extended to the surface of the initial support. However, a cutting line or marking line is reserved in the center area corresponding to the future opening for easy positioning later. When the lining trolley reaches this section, formwork erection and pouring are no longer carried out. Instead, it moves forward across this section and directly reaches the next non-opening section for secondary lining construction. This skipped section forms a reserved window in the longitudinal direction, covered only by the reinforced initial support and the waterproof layer. Its longitudinal length is 5.5m, which is greater than the longitudinal dimension of the transverse smoke exhaust duct inlet (5.0m). Operating space is reserved at both ends.

[0070] During construction breaks in skipped sections, the lining trolley is moved and parked in that section. Its curved steel formwork is used to provide temporary mechanical support against the surface of the initial support, preventing excessive deformation of the initial support and serving as a construction protective barrier to prevent debris from falling in or mechanical collisions from damaging the initial support during subsequent construction processes.

[0071] Step S3: Do not open the initial support yet, and open the smoke exhaust channel.

[0072] In sections where secondary lining is skipped, the initial support will not be opened temporarily, and the inner surface of the initial support 101 of the main tunnel will remain completely closed. Construction will begin on the auxiliary tunnels and the upper network of the smoke exhaust and ventilation system within the rescue station section 300 meters past the rescue station. After the longitudinal smoke exhaust channel 5 and the transverse smoke exhaust channel 6 of the upper network of the smoke exhaust and ventilation system are in place, the smoke exhaust shaft 4 will be connected via a counter-excavation method.

[0073] like Figure 2 As shown in the enlarged schematic diagram, the opposing through-connection structure of the horizontal smoke exhaust duct, the upper section of the smoke exhaust shaft, the initial support external duct, and the lower section of the smoke exhaust shaft is illustrated. The specific step-by-step construction path of the smoke exhaust duct network is as follows: (1) First, construct the longitudinal smoke exhaust channel 5, which is formed by excavating along the longitudinal direction of the tunnel from the side of the inclined shaft 3.

[0074] (2) Then, construct the transverse smoke exhaust channels 6. Starting from the completed longitudinal smoke exhaust channels 5, excavate horizontally in the direction of the main tunnel (i.e., the transverse direction of the main tunnel) to form multiple transverse smoke exhaust channels 5. Excavation stops after reaching the predetermined vertical position, i.e. the predetermined top position of the subsequent smoke exhaust shaft 4.

[0075] (3) Then, starting from the bottom of the transverse smoke exhaust channel 6, excavation is carried out vertically downward to form the upper section 4a of the upper smoke exhaust shaft. After excavation to a certain depth, it is not excavated through yet. A portion of rock and soil can be reserved in the center to wait for it to be connected to the lower shaft section from the opposite direction.

[0076] (4) Demolish the initial support and construct the external passage of the initial support. Inside the main tunnel 1, at the skip section location, demolish the initial support 101 of the main tunnel. Use mechanical cutting to precisely cut the shotcrete layer along the marked opening outline, and then use oxyacetylene flame to cut off the steel frame support within the outline in sections. After demolishing the opening, excavate a section of the external passage 4c of the initial support from the opening outwards laterally. The excavation length should be based on reaching the stable surrounding rock strata to facilitate the upward excavation of the vertical shaft.

[0077] (4) The lower section 4b of the lower smoke exhaust shaft is connected to the upper section 4a. The lower section 4b of the lower smoke exhaust shaft is formed by excavating vertically upward from the end of the initial support external passage 4c, and is excavated in the opposite direction to the upper section 4a of the already constructed upper smoke exhaust shaft. The opposite excavation can improve the connection efficiency and facilitate the construction of the locking ring beam after connection. After connection, a locking ring beam is set at the connection position. The locking ring beam is made of reinforced concrete and reinforces the connection joint to ensure the structural stability of the smoke exhaust shaft, and finally forms a complete smoke exhaust shaft 4.

[0078] (5) After all the smoke exhaust channels are completed, install and test the electric air valve in the transverse smoke exhaust channel 6.

[0079] This embodiment employs an innovative parallel operation construction organization. The main tunnel utilizes Level I mechanized equipment, including a three-arm rock drilling rig, a wet spraying robot, and a self-propelled inverted arch trestle, while the auxiliary tunnels utilize Level II equipment, such as pneumatic rock drilling rigs and small wet spraying machines.

[0080] In terms of labor allocation, there are approximately 50 workers on the main tunnel construction team (excavation, support, reinforcement, lining, etc.), and approximately 15 workers on the auxiliary tunnel construction team (about one-third of the number on the main tunnel). This resource allocation enables the simultaneous and efficient construction of the main tunnel and auxiliary tunnels in the same work area, avoiding resource idleness.

[0081] By adopting the construction method of this embodiment, the No. 3 inclined shaft construction area simultaneously completed the construction of all auxiliary tunnels within the rescue station while undertaking the main tunnel construction task. Compared with the traditional sequential construction method of first constructing the main tunnel and then the auxiliary tunnels, the construction period of this invention is significantly shortened by approximately 6 months. Furthermore, due to the adoption of skip-formwork construction and the technique of temporarily not opening the initial support, the construction time for opening the flue gas duct is reduced by approximately 70%, and no damage to the lining structure caused by opening occurs. This invention demonstrates excellent technical advancement, practicality, and economy.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the construction of a tunnel provided with a rescue station and with a semi-transversal smoke extraction ventilation system comprising an upper network and a smoke extraction shaft (4), the upper network comprising longitudinal smoke extraction channels (5) and transversal smoke extraction channels (6) communicating with each other, characterized in that, Includes the following steps: Step S1: Construct the main tunnel (1) and continuously construct the initial support (101) along the entire length of the main tunnel (1). Step S2: Within the length of the main tunnel located at the rescue station section (2), the secondary lining (102) is constructed longitudinally along the tunnel using a skip-formwork method, wherein: At the location where the flue gas duct opening is to be opened, a reinforced primary support (101) structure is constructed. The primary support (101) structure remains intact and is not opened for the time being, but the secondary lining (102) of this section is skipped, so that this section is supported by the primary support (101) alone. At locations where no flue opening is planned, the initial support (101) and secondary lining (102) are constructed sequentially according to the conventional procedures. Furthermore, the lining trolley is moved to the section that skips the secondary lining (102) and parked there. The arc-shaped steel formwork of the lining trolley is used to provide temporary mechanical support and construction protection for the initial support (101). Step S3: When the construction position of the initial support (101) of the main tunnel (1) exceeds the starting position of the rescue station by 200-350 meters, the construction of the auxiliary tunnel (7) and the upper network of the smoke exhaust and ventilation system in the rescue station section (2) begins; the auxiliary tunnel (7) includes the left horizontal guide and the right horizontal guide; Step S4: After the upper network of the smoke exhaust ventilation system is in place, at the location where the smoke exhaust duct opening is to be opened in step S2, the initial support (101) of the main tunnel is broken; during the breaking, the sprayed concrete layer is cut along the outline by mechanical cutting and the steel frame support is cut off in sections, and the outer passage of the initial support (4c) is formed by excavating outward from the side of the main tunnel; then the smoke exhaust shaft (4) is excavated vertically upward, so that the smoke exhaust shaft (4) is connected to the transverse smoke exhaust duct (6) that has been completed above, and is connected to the longitudinal smoke exhaust duct (5) through the transverse smoke exhaust duct (6). Among them, the longitudinal smoke exhaust channel (5) is formed by excavating along the longitudinal direction of the main tunnel from the side wall of the inclined shaft (3), and the transverse smoke exhaust channel (6) is formed by excavating horizontally from the longitudinal smoke exhaust channel (5) towards the main tunnel (1).

2. A construction method of a rescue station provided with a semi-transverse smoke exhaust ventilation system of a tunnel according to claim 1, characterized in that, At least part of the smoke exhaust shaft (4) is formed by excavating downwards from the bottom of the horizontal smoke exhaust channel (6).

3. A method of constructing a tunnel with a rescue station provided with a semi-transverse smoke exhaust ventilation system according to claim 2, characterized in that, In step S4, the smoke exhaust shaft (4) is excavated in opposite directions, including: excavating downward from the bottom of the transverse smoke exhaust channel (6) to form the upper section (4a) of the smoke exhaust shaft; excavating upward from the end of the initial support channel (4c) to form the lower section (4b) of the smoke exhaust shaft; after the upper section (4a) and the lower section of the smoke exhaust shaft are connected, a locking ring beam is set at the connection position.

4. A construction method of a rescue station provided with a semi-transverse smoke exhaust ventilation system of a tunnel according to claim 1, characterized in that, In step S2, at the location where the exhaust duct opening is to be opened, the initial support (101) structure adopts a reinforced design, including: the spacing of the steel frame supports is increased to 0.6m to 0.8m / frame, and / or the thickness of the sprayed concrete is 20cm to 30cm.

5. A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station according to claim 4, characterized in that, A transition section is provided between the reinforced initial support (101) structure and the conventional initial support (101) structure, in which the spacing of the steel frame supports gradually transitions from the conventional spacing to the denser spacing.

6. A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station according to claim 1, characterized in that, In step S2, the longitudinal length of the section that skips the secondary lining (102) is 4m to 8m.

7. A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station according to claim 1, characterized in that, In step S3, after the initial support (101) of the main tunnel (1) is 200-350 meters past the rescue station, the main tunnel continues to advance forward. At the same time, the construction of the auxiliary tunnel (7) and the upper network of the smoke exhaust and ventilation system in the rescue station section (2) is started, so as to realize the parallel operation of the main tunnel and the auxiliary tunnel (7).

8. A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station according to claim 7, characterized in that, The distance between the working face of the main tunnel and the working face of the auxiliary tunnel (7) shall not be less than 30m.

9. A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station according to claim 1, characterized in that, In step S2, when constructing secondary lining (102) at a location where the flue gas duct opening is not predetermined, waterstops are pre-installed at both construction joints.

10. A construction method for a tunnel with a semi-lateral smoke exhaust ventilation system for a rescue station according to claim 9, characterized in that, In step S2, when constructing the secondary lining (102) at a location where the flue gas duct opening is not predetermined, pre-embedded connecting bars are constructed at both ends of the secondary lining.

Images