A structure and construction method suitable for a GIL river-crossing pipe gallery

Abstract

The application discloses a structure suitable for a GIL river-crossing pipe gallery, which comprises a double-layer stress system formed by an outer lining structure and an inner internal structure. The outer lining structure is formed by staggered joint assembly of prefabricated pipe segments, and a full-ring embedded adapter is arranged on an inner arc surface and used for equipment fixation and structure connection. The inner internal structure comprises a track structure, prefabricated bearing members and cast-in-place bearing members. The bottom of the prefabricated bearing members is filled with filling connection material, and the prefabricated bearing members are connected to the cast-in-place bearing members anchored by the embedded steel bars to form an integral bearing frame to support the GIL equipment. The internal space of the pipe gallery is divided into an equipment passing space, a reserved cable space, a maintenance channel space and a collection space from top to bottom. The application can separate the stress of water and soil pressure and equipment load, improve the safety reserve of the pipe gallery structure, improve the assembly construction efficiency through the prefabricated and cast-in-place combined structure, and guarantee the grounding connection reliability through the embedded adapter. The standardized space partition effectively meets the long-term safe operation and maintenance and protection requirements of the GIL power transmission.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology for ultra-high voltage power transmission projects, and more specifically, to a structure and construction method applicable to GIL (Gas Infrared Transmission) river-crossing tunnels. Background Technology

[0002] With the continuous advancement of ultra-high voltage AC / DC transmission projects, GIL (Gas Insulated Metal Enclosed Transmission Line) high-voltage levels such as ±800kV and 500kV are increasingly being laid underground via tunnels and galleries across rivers and seas. GIL equipment plays a crucial role in energy transmission due to its large transmission capacity and low losses. However, its heavy weight, high installation precision, and stringent environmental requirements place extremely high demands on the civil engineering bearing capacity, construction precision, and long-term operation and maintenance space planning of underground tunnel galleries.

[0003] In current underground tunnel construction practices, river-crossing tunnels largely rely on the structural design systems of conventional municipal utility tunnels or ordinary power tunnels. For example, there is an existing method for the layout of GIL power transmission flow sections in river-crossing tunnels with multiple adaptability features. However, in terms of specific civil engineering structures, current technologies typically employ an integral mixed-stress lining mode, and the internal support structures of the tunnels are mostly constructed using cast-in-place concrete. Regarding equipment fixing and pipeline installation, current tunnel structures often involve post-construction anchoring after the main structure is completed. Furthermore, the utilization of internal space has not been systematically and meticulously divided to accommodate the different operating and maintenance conditions of ultra-high voltage equipment.

[0004] However, when facing large-diameter (greater than 10m) and complex river-crossing tunnels, the shortcomings and deficiencies of existing technologies gradually become apparent. Specifically: First, traditional utility tunnels do not employ a layered internal and external stress-bearing system. External water and soil pressure and internal GIL (Gas Injection Line) equipment loads are combined into one group, resulting in unclear stress division and insufficient structural safety reserves under deep burial and high water and soil pressure conditions. Second, existing tunnel structures lack systematic pre-embedded connection structures. The installation and fixing of monitoring equipment and auxiliary cable equipment are relatively chaotic, and the reliability of grounding connections between the structure and GIL equipment is poor, making it difficult to fully comply with the grounding and safe operation specifications for ultra-high voltage power transmission projects. Third, the internal structure mostly adopts a fully cast-in-place construction mode, resulting in low prefabrication levels, long construction cycles, and difficulty in adapting to the requirements of river-crossing tunnel construction and subsequent settlement and deformation coordination. Fourth, the internal space of conventional utility tunnels lacks specialized functional zoning. There is no coordinated allocation of GIL equipment passage space, reserved cable space, maintenance passage space, and dedicated SF6 collection space, leading to chaotic operation and maintenance layout, insufficient long-term expansion capacity, and a lack of fault safety protection. Fifth, the strata where the cross-river utility tunnel is located are rich in groundwater, and the existing structure lacks dedicated drainage, waterproofing and protective facilities, which can easily lead to water accumulation in the trench or leakage in the lining, thereby affecting the service life and operational safety of the GIL power transmission equipment. Summary of the Invention

[0005] The purpose of this invention is to separate water and soil pressure from equipment load, thereby improving the safety reserve of the utility tunnel structure; to improve the efficiency of prefabricated construction through a combination of prefabrication and cast-in-place construction, and to ensure the reliability of grounding connection through pre-embedded connections; and to effectively meet the long-term safe operation and maintenance and protection requirements of GIL power transmission through standardized spatial zoning.

[0006] To achieve the above objectives, a first aspect of the present invention provides a structure suitable for GIL (Gas-Insulated Line) river-crossing tunnels, comprising: The outer lining structure is used to enclose the external bearing boundary of the cross-river utility tunnel and bear the water and soil pressure outside the tunnel; The inner internal structure is located within the outer lining structure and is used to bear the vertical load and operational load of the power transmission equipment; The pre-embedded connection structure is set on the inner side of the outer lining structure and is used to connect the inner internal structure and fix the equipment in the pipe gallery; The inner internal structure includes a track structure for the installation or passage of the power transmission equipment, a prefabricated bearing member for supporting the power transmission equipment, and a cast-in-place bearing member that cooperates with the prefabricated bearing member. A filling connection material is provided between the prefabricated bearing member and the outer lining structure. The cast-in-place bearing member is connected to the outer lining structure and forms a combined bearing structure with the prefabricated bearing member. The internal space of the cross-river utility tunnel includes equipment passage space, reserved cable space, maintenance passage space, and collection space.

[0007] In one embodiment of the present invention, the outer lining structure includes a multi-ring precast segment structure arranged sequentially along the longitudinal direction of the pipe gallery. The multi-ring precast segment structure is arranged with one ring every 2m along the longitudinal direction of the pipe gallery, and each ring of the precast segment structure is divided into 8 segments. Each ring of the precast segment structure is formed by assembling multiple segments. The segments of adjacent rings are staggered, and adjacent segments within the same ring are connected by connectors, including bolt connectors. The power transmission equipment is the GIL power transmission equipment.

[0008] In one embodiment of the present invention, the pre-embedded connection structure includes a plurality of steel bar connectors arranged in a full ring along the inner arc surface of the outer lining structure. The steel bar connectors are used to fix the monitoring equipment and auxiliary cable equipment, and to connect the steel bars of the cast-in-place load-bearing member to the outer lining structure to form a grounding connection path.

[0009] In one embodiment of the present invention, the prefabricated load-bearing component is a prefabricated "U"-shaped component, which is disposed on the lower inner side of the outer lining structure; The cast-in-place load-bearing component is a cast-in-place "arc" shaped plate, which is set along the inner arc surface of the outer lining structure; The precast load-bearing components and the cast-in-place load-bearing components together form the support structure of the power transmission equipment.

[0010] In one embodiment of the present invention, the outer side of the prefabricated "U"-shaped component is provided with a connecting structure for connecting with the cast-in-place "arc"-shaped slab. The cast-in-place "arc"-shaped slab is connected to the outer lining structure by means of rebar installation. The filling connecting material is densely filled in the gap between the prefabricated "U"-shaped component and the outer lining structure.

[0011] In one embodiment of the present invention, the prefabricated load-bearing component includes a top plate, two side walls located below the top plate, and a bottom plate connecting the bottom of the two side walls; The bottom surface of the base plate is provided with multiple bottom convex surfaces, which are used to level the posture between the prefabricated load-bearing component and the inner arc surface of the outer lining structure. The outer sides of the two side walls are respectively provided with corbels, and an assembly auxiliary device is arranged below the corbels. The corbels and the assembly auxiliary device are used to assist in the hoisting and positioning assembly of the prefabricated load-bearing components. The base plate has through grouting holes, which are used to inject the filling and connecting material into the gap between the bottom of the precast bearing member and the outer lining structure. The surface of the top plate is provided with longitudinal bolt holes for auxiliary positioning or hoisting, and the joint between two adjacent prefabricated load-bearing components is a flat joint and is sealed with fireproof sealant.

[0012] In one embodiment of the present invention, the equipment passage space is a GIL equipment passage space, which is located in the upper area of ​​the cross-river tunnel, while the reserved cable space, the maintenance passage space, and the collection space are located in the lower area of ​​the cross-river tunnel, so that the cross-river tunnel can simultaneously accommodate GIL equipment passage, long-term cable laying, maintenance operations, and fault gas collection.

[0013] In one embodiment of the present invention, a cabinet installation area is partially set within the maintenance passage space, the reserved cable space is separated from the collection space, and the collection space is located at a lower position suitable for collecting leaked SF6 gas.

[0014] In one embodiment of the present invention, the inner internal structure further includes a leveling layer, a backfill layer, a drainage ditch, a waterproof layer, and a protective cover structure covering the drainage ditch, all located around the track structure or the combined load-bearing structure.

[0015] In one embodiment of the present invention, the filling and connecting material is mortar or fine stone concrete, the leveling layer is a concrete sealing and curing surface layer, the backfill layer is a plain concrete backfill layer, the waterproof layer is a polymer cement waterproof mortar layer applied to the surface of the drainage ditch, and the protective cover structure is a steel grating.

[0016] A second aspect of the present invention provides a construction method applicable to GIL (Gas Infrared Utility Tunnel) river-crossing tunnels, suitable for the structures described above, comprising the following steps: S1. Construct an outer lining structure to form the outer bearing boundary of the pipe gallery, and pre-embed multiple pre-embedded connection structures on the inner arc surface of the outer lining structure. S2. A cast-in-place track structure is placed inside the lower part of the outer lining structure to serve as the foundation for leveling the base and installing power transmission equipment. S3. The prefabricated load-bearing components are hoisted and installed on the track structure, and filling connection material is provided in the gap between the prefabricated load-bearing components and the outer lining structure; S4. Cast-in-place load-bearing components are provided on both sides of the precast load-bearing components and between the inner arc surfaces of the outer lining structure, and the cast-in-place load-bearing components are connected to the outer lining structure and the precast load-bearing components to form an integral load-bearing frame by means of rebar installation and the pre-embedded connection structure. S5. Divide the internal space of the cross-river utility tunnel into functional spaces, and set up equipment passage space, reserved cable space, maintenance passage space and collection space in the upper and lower sections.

[0017] The present invention has the following beneficial effects: This invention, through a series of innovative stress, structural, and spatial design schemes, effectively overcomes many shortcomings of existing cross-river utility tunnels in terms of load distribution, construction assembly, and comprehensive operation and maintenance, achieving excellent comprehensive engineering benefits. Firstly, addressing the problem of insufficient safety reserves due to unclear stress in traditional structures, this invention adopts a double-layered, split-structure stress system consisting of an outer lining and an inner internal structure. The outer layer is specifically designed to resist external water and soil pressure, while the inner layer is dedicated to bearing the load of GIL (Gas Injection Line) equipment, making the overall stress logic clearer and improving the structural safety of large-diameter utility tunnels under deep burial conditions. Secondly, addressing the shortcomings of traditional cast-in-place methods, such as low prefabrication and weak adaptability to deformation, the inner structure of this invention uses a combination of prefabricated "U"-shaped components and cast-in-place "arc"-shaped slabs. This design effectively increases the proportion of prefabricated construction and accelerates the project progress, while also better adapting to the later settlement and deformation of underground tunnels. Secondly, addressing the issues of dispersed equipment installation and poor grounding performance, this invention pre-embeds steel rebar connectors around the entire inner arc surface of the outer lining. This not only provides a standardized and uniform fixed base for monitoring and auxiliary cable equipment but also connects the cast-in-place structural steel reinforcement to the lining, ensuring the continuity of structural grounding. Finally, addressing the problems of disordered internal space and lack of drainage and flood control facilities in existing utility tunnels, this solution standardizes the cross-section into dedicated functional zones, comprehensively considering the passage of GIL equipment, future cable expansion, routine maintenance, and safe collection space for fault gas SF6. Furthermore, it includes a reserved drainage ditch, waterproof mortar, and steel grating at the bottom, providing excellent waterproofing, drainage, and protection performance. This makes it highly adaptable to the complex working conditions of river-crossing tunnels with abundant groundwater, thereby enhancing the long-term operation and maintenance performance and compatibility of the equipment. Attached Figure Description

[0018] Figure 1 This is an overall structural diagram of a structure suitable for a GIL (Gas Infrared Utility Tunnel) across a river, according to an embodiment of the present invention. Figure 2 This is a structural diagram of a prefabricated "U"-shaped component suitable for the structure of a GIL (Gas Infrared Irrigation System) cross-river tunnel, according to an embodiment of the present invention.

[0019] Figure Labels

[0020] 1. Outer lining structure; 2. Track structure; 3. Precast "U"-shaped components; 4. Cast-in-place "arc"-shaped slabs; 5. Filling and connecting materials; 6. Leveling layer; 7. Backfill layer; 8. Polymer cement waterproof mortar; 9. Steel grating; 10. GIL transmission equipment; 11. Monitoring equipment; 12. Auxiliary cable equipment; 13. Equipment passage space; 14. Reserved cable space; 15. Maintenance passage space; 16. SF6 collection space; 21. Longitudinal bolt holes; 22. Top slab; 23. Corbel; 24. Assembly auxiliary device; 25. Side wall; 26. Bottom slab; 27. Grouting hole; 28. Bottom convex surface. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0022] In the first embodiment of this invention, a structural design method and corresponding structure suitable for GIL (Gas-Insulated Metal-Enclosed Transmission Line) river-crossing tunnels are provided. Taking the Wuhu GIL river-crossing tunnel project of the Gansu-Zhejiang ±800kV UHVDC transmission project as an example, the diameter of the tunnel is greater than 10m. Furthermore, GIL stands for Gas-Insulated Metal-Enclosed Transmission Line. In this invention, GIL refers to a type of high-voltage transmission line that uses insulating gas as the insulating medium and a metal pipe as the outer shell. This technology has the characteristics of large transmission capacity and low operating loss, and is widely applicable to underground tunnels or river-crossing tunnels in ±800kV, 500kV, and other UHVAC / DC transmission projects. Further, the insulating gas is SF6 gas, i.e., sulfur hexafluoride.

[0023] Combination Figure 1 As shown, the GIL (Gas Infrared Transmission) tunnel adopts a double-layer load-bearing system with a separate outer lining and inner structure. The outer lining bears the external water and soil pressure, while the inner structure is specifically designed to bear the vertical and operational loads of the GIL transmission equipment, thus achieving a step-by-step transfer of loads and a clear division of stress.

[0024] The outer bearing boundary is the outer lining structure 1, which in this embodiment adopts a precast reinforced concrete structure. According to the requirements of the river-crossing tunnel, the maximum overburden thickness of the tunnel roof in the middle section is about 40 meters, and the maximum water depth is about 24 meters. The maximum water pressure is 6.4 bar. The segment thickness is set at 0.55 meters (the ratio to the tunnel diameter is 0.04741), the concrete strength grade is C60, the impermeability grade is P12, and the reinforcement is divided according to the tunnel burial depth (the steel content of the shallow buried section is about 145 kg / m³, and the steel content of the deep buried section is about 170 kg / m³).

[0025] The outer lining structure comprises a multi-ring precast tunnel segment structure arranged longitudinally along the pipe gallery. Each ring of the multi-ring precast tunnel segment structure is positioned every 2 meters along the longitudinal direction of the pipe gallery. Each ring consists of 8 segments, assembled from multiple segments. The joints of adjacent rings are staggered, and adjacent segments within the same ring are connected by connectors, including bolted connectors. To meet the requirements for equipment fixing and structural grounding, 36 steel rebar connectors are pre-embedded throughout the inner arc surface of the outer lining structure 1. Figure 1 It can be seen that the monitoring equipment 11 located on both sides of the upper part of the pipe gallery, and the auxiliary cable equipment 12 located on both sides of the waist of the pipe gallery, are all fixed to the outer lining structure 1 through these pre-embedded steel bar connectors, which at the same time ensures the overall grounding connectivity.

[0026] In the lower half of the inner lining structure 1, an inner internal structure for supporting the equipment is arranged. A precast load-bearing component, a precast U-shaped component 3, is installed at the center. The main function of the precast U-shaped component 3 is to support the upper GIL equipment, and the bottom gap between it and the outer lining structure 1 is filled tightly by a filling connecting material 5. Furthermore, the precast U-shaped component 3 is a precast reinforced concrete structure. Furthermore, the filling connecting material 5 is M10 mortar or C30 fine aggregate concrete.

[0027] Symmetrically arranged on both sides of the precast load-bearing components are cast-in-place load-bearing components, which are cast-in-place "arc"-shaped slabs 4. One end of the cast-in-place "arc"-shaped slab 4 is connected to the outer lining structure 1 by means of rebar anchoring, and the other end is connected to the connector reserved on the outside of the precast "U"-shaped component 3, together forming the lower combined support frame. Above it, a cast-in-place reinforced concrete track structure 2 is set up to complete the base leveling and serve as the installation foundation for the equipment. The GIL transmission equipment 10 in the figure is stably placed on the track structure 2.

[0028] The internal structure is also equipped with waterproofing and drainage systems on its surface and bottom. These include a leveling layer 6, which is constructed after the tunnel has settled and stabilized, and a backfill layer 7, which is made of plain concrete. The backfill layer 7 has drainage ditches pre-formed at the bottom, and the surface of the drainage ditches is coated with polymer cement waterproof mortar 8. A steel grating 9 is installed at the top opening for protection.

[0029] In addition, combined Figure 1The internal space of the utility tunnel is systematically functionally divided. The upper part of the cross-section is the equipment passage space 13, which further serves as the passage space for GIL equipment and railcars. The lower part of the cross-section is divided into several dedicated areas by prefabricated "U"-shaped components 3: the interior of the prefabricated "U"-shaped components 3 forms the maintenance passage space 15, and some sections of the maintenance passage space 15 can be equipped with cabinets; the upper area on both sides is divided into reserved cable spaces 14, which are reserved cable spaces for future use; the cavity at the bottom is divided into a dedicated SF6 collection space 16, thereby meeting the safety requirements for future expansion, daily maintenance, and fault gas collection.

[0030] In the second embodiment of the present invention, combined with Figure 2 As shown, this embodiment, based on Embodiment 1, further discloses the specific structural details of the prefabricated load-bearing component in the inner layer structure. The prefabricated load-bearing component is a prefabricated "U"-shaped component 3.

[0031] In this embodiment, the precast "U"-shaped component 3 is a precast reinforced concrete component with a concrete strength grade of C40. The overall external dimensions of the precast "U"-shaped component are set to a width of 4.1 meters and a height of 3.53 meters, with each section approximately 2 meters long along the tunnel's longitudinal direction. It primarily serves as the main vertical support component for the GIL power transmission equipment. Combined with... Figure 2 The specific construction of the tag is described below: Top plate 22: Located above the orifice-shaped component, with a thickness of 0.33 meters. The internal steel reinforcement cage of top plate 22 uses Φ18@100 steel bars in both the upper and lower rows. The surface of top plate 22 has longitudinal bolt holes 21, which can be used for component hoisting or auxiliary positioning. In addition, the ends of the top plate are reserved with threaded steel bar connectors, and the top of top plate 22 is the mounting foundation for the GIL equipment support, which is installed on it using chemical anchors.

[0032] Side walls 25: Located on both sides of the shaped component, with a thickness of 0.3 meters. The interior of side walls 25 is reinforced with Φ16@100 steel bars. Outer sides of side walls 25 extend corbels 23, with assembly auxiliary devices 24 located below the corbels. Both are used to assist in the spatial positioning and assembly of the shaped component during the synchronous hoisting phase of the pipe gallery construction. Additionally, threaded steel bar connectors are pre-installed on the outer side of side walls 25 for subsequent mechanical connection to the steel bars within the cast-in-place "arc"-shaped slab.

[0033] Bottom plate 26: Located at the bottom of the orifice component, with a thickness of 0.18 meters. The interior of bottom plate 26 is reinforced with Φ12@100 steel bars. A grouting hole 27 is drilled through the central area of ​​bottom plate 26. After the orifice component is positioned, filling and connecting material can be injected into the gap between the bottom of the orifice component and the outer lining structure through the grouting hole 27 to ensure the dense filling of the bottom rigid load-bearing layer. The rigid load-bearing layer refers to the filling and connecting material (M10 mortar or C30 fine aggregate concrete) in the inner structure. This rigid load-bearing layer is densely filled in the gap between the precast load-bearing component and the outer lining structure.

[0034] Bottom convex surface 28: Multiple bottom convex surfaces 28 are provided on the bottom surface of the base plate 26. Specifically, each die has four bottom convex surfaces 28, each with dimensions of 0.6 meters (width) × 0.3 meters (length) × 0.05 meters (thickness). By providing bottom convex surfaces 28, the die can be temporarily and stably positioned on the inner arc surface of the tunnel during installation, achieving posture leveling between the die and the inner arc surface of the tunnel segment.

[0035] In terms of assembly and connection, the joints between adjacent precast sections are flat joints, sealed with fire-retardant sealant. After installation, reinforced concrete "arc"-shaped slabs are cast-in-place on both sides of the precast sections. The reinforcing bars of the cast-in-place "arc"-shaped slabs are screwed into pre-installed connectors on the outside of the precast sections, thus achieving a physical connection with the internal reinforcing bars of the sections. Together, they form the combined support system of the GIL equipment.

[0036] In the third embodiment of the present invention, based on the first embodiment, the specific layout and fixed connection structure of the outer lining structure and its full-ring pre-embedded connection system are further disclosed. In this embodiment, the precast reinforced concrete segments used in the outer lining structure have a thickness of 0.55 meters, and the ratio of the segment thickness to the diameter of the tunnel is 0.04741. Depending on the burial depth of the river-crossing tunnel, a tiered reinforcement strategy is adopted for the segments: the steel content of the shallow-buried segments is approximately 145 kg / m³, and the steel content of the deep-buried segments is approximately 170 kg / m³.

[0037] To accommodate both equipment mounting and overall structural grounding requirements, 36 steel rebar connectors are pre-embedded throughout the inner arc surface of the outer lining structure. The specific layout logic of these 36 steel rebar connectors is as follows: Circumferential arrangement: Taking the center of the capping block of the pipe ring as the reference point, a steel bar connector is arranged every 10° along the circumference of the pipe segment.

[0038] Longitudinal arrangement position: along the advancing direction of the tunnel segments, located 0.3 meters behind the center line of each ring of tunnel segments.

[0039] Segment quantity allocation: In the 8 segments of the first ring, 5 steel rebar connectors are arranged in each of the capping block, the first standard block, the third standard block and the fifth standard block; 4 steel rebar connectors are arranged in each of the remaining segments.

[0040] For structural fixation, the rebar connectors are pre-embedded inside the tunnel lining segments, with their tops flush with the inner arc surface of the segments. The tail of the rebar connector is welded to the rebar cage inside the segments via rebar. Double-sided welding is used, and the weld length is required to be no less than 6D (where D is the diameter of the rebar) to ensure the connector's tensile strength and grounding conductivity under equipment loads. In subsequent construction, the rebar of the internal cast-in-place "arc"-shaped slab can be reliably connected to the pre-embedded connectors through methods such as rebar installation, forming an integrated grounding network.

[0041] In the fourth embodiment of the present invention, a construction method suitable for GIL (Gas Infrared Utility Tunnel) river-crossing tunnels is provided, mainly used to realize the tunnel structures in embodiments one to three above. Specifically, it includes the following construction steps: Step S1, assembly of the outer lining structure: The outer lining structure is constructed by assembling precast segments in staggered joints, with each segment consisting of eight precast segments arranged in 2-meter rings along the longitudinal direction of the tunnel. During assembly, 36 steel rebar connectors are pre-embedded on the inner arc surface of each segment.

[0042] Step S2, cast-in-place foundation track structure: A reinforced concrete track structure was cast in place at the tunnel foundation. This track structure primarily serves as the foundation for leveling the tunnel foundation and for the subsequent installation of GIL power transmission equipment.

[0043] Step S3: Hoisting and filling connection materials for prefabricated "U"-shaped components: Precast "U"-shaped components were hoisted simultaneously. The installation and positioning of the precast "U"-shaped components used the tunnel centerline as the positioning reference, controlling the deviation between the vertical centerline of the precast "U"-shaped component and the tunnel centerline to be within ±3mm. The four bottom convex surfaces on the bottom of each "U"-shaped component temporarily and stably positioned it on the inner arc surface of the tunnel. After positioning, the gap between the precast component and the lining was filled with grout using a filling and connecting material, and connectors were provided on the outside of the "U"-shaped component for subsequent overlapping. The filling and connecting material was C30 fine aggregate concrete or M10 mortar. Step S4, connection of cast-in-place "arc" shaped slab and overall structure: On-site reinforcement was tied and cast-in-place "arc"-shaped slabs were poured. The cast-in-place "arc"-shaped slabs were connected to the outer lining structure via rebar anchoring. Φ18 rebars were used for anchoring, with an anchoring depth of 20D (D being the rebar diameter). During construction, the rebars were slowly inserted into the holes, and installation was carried out within the specified curing time to ensure the anchoring agent adhered evenly to the surface and gaps of the rebars. After the anchoring agent cured, welding, rebar tying, and concrete pouring were carried out. Simultaneously, the reinforcement of the cast-in-place "arc"-shaped slabs was connected to connectors on precast "U"-shaped components to form an integral load-bearing frame.

[0044] Step S5, subsequent construction of the protective system: After the tunnel is completed and the structural settlement is stable, a concrete sealing and curing leveling layer is constructed. Subsequently, plain concrete is used to backfill and form drainage ditches. Polymer cement waterproof mortar is applied to the inner surface of the drainage ditches, and steel grating is installed on top of them.

[0045] Step S6, Equipment Layout and Space Zoning: GIL transmission equipment, monitoring equipment, and auxiliary cables are laid out in zones within the utility tunnel. Pre-embedded steel rebar connectors are used to uniformly fix and ground the monitoring equipment and auxiliary cables. Spatially, the tunnel includes upper sections for GIL equipment and railcar passage, lower sections for reserved cable space, maintenance access, and SF6 collection.

[0046] The present invention has the following beneficial effects: This invention, through a series of innovative stress, structural, and spatial design schemes, effectively overcomes many shortcomings of existing cross-river utility tunnels in terms of load distribution, construction assembly, and comprehensive operation and maintenance, achieving excellent comprehensive engineering benefits. Firstly, addressing the problem of insufficient safety reserves due to unclear stress in traditional structures, this invention adopts a double-layered, split-structure stress system consisting of an outer lining and an inner internal structure. The outer layer is specifically designed to resist external water and soil pressure, while the inner layer is dedicated to bearing the load of GIL (Gas Injection Line) equipment, making the overall stress logic clearer and improving the structural safety of large-diameter utility tunnels under deep burial conditions. Secondly, addressing the shortcomings of traditional cast-in-place methods, such as low prefabrication and weak adaptability to deformation, the inner structure of this invention uses a combination of prefabricated "U"-shaped components and cast-in-place "arc"-shaped slabs. This design effectively increases the proportion of prefabricated construction and accelerates the project progress, while also better adapting to the later settlement and deformation of underground tunnels. Secondly, addressing the issues of dispersed equipment installation and poor grounding performance, this invention pre-embeds steel rebar connectors around the entire inner arc surface of the outer lining. This not only provides a standardized and uniform fixed base for monitoring and auxiliary cable equipment but also connects the cast-in-place structural steel reinforcement to the lining, ensuring the continuity of structural grounding. Finally, addressing the problems of disordered internal space and lack of drainage and flood control facilities in existing utility tunnels, this solution standardizes the cross-section into dedicated functional zones, comprehensively considering the passage of GIL equipment, future cable expansion, routine maintenance, and safe collection space for fault gas SF6. Furthermore, it includes a reserved drainage ditch, waterproof mortar, and steel grating at the bottom, providing excellent waterproofing, drainage, and protection performance. This makes it highly adaptable to the complex working conditions of river-crossing tunnels with abundant groundwater, thereby enhancing the long-term operation and maintenance performance and compatibility of the equipment.

[0047] The embodiments described above are merely further illustrations of the present invention and are not intended to limit the present invention in any other way. The present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding modifications and changes based on the present invention, but all such modifications and changes should fall within the protection scope of the present invention.

Claims

1. A structure suitable for GIL (Gas Infrared Utility Tunnel) river-crossing tunnels, characterized in that, include: The outer lining structure is used to form the external bearing boundary of the cross-river utility tunnel and to bear the water and soil pressure outside the tunnel; The inner internal structure is set within the outer lining structure and is used to bear the vertical load and operational load of the power transmission equipment; The pre-embedded connection structure is set on the inner side of the outer lining structure and is used to connect the inner internal structure and fix the equipment in the pipe gallery; The inner internal structure includes a track structure for the installation or passage of the power transmission equipment, a prefabricated bearing member for supporting the power transmission equipment, and a cast-in-place bearing member that cooperates with the prefabricated bearing member. A filling connection material is provided between the prefabricated bearing member and the outer lining structure. The cast-in-place bearing member is connected to the outer lining structure and forms a combined bearing structure with the prefabricated bearing member. The internal space of the cross-river utility tunnel includes equipment passage space, reserved cable space, maintenance passage space, and collection space.

2. The structure according to claim 1, characterized in that, The outer lining structure includes a multi-ring precast segment structure arranged sequentially along the longitudinal direction of the pipe gallery. The multi-ring precast segment structure is set with one ring every 2m along the longitudinal direction of the pipe gallery, and each ring of the precast segment structure is divided into 8 segments. Each ring of the precast segment structure is formed by assembling multiple segments. The segments of adjacent rings are staggered, and adjacent segments within the same ring are connected by connectors, including bolt connectors. The power transmission equipment is the GIL power transmission equipment.

3. The structure according to claim 2, characterized in that, The pre-embedded connection structure includes multiple steel bar connectors arranged in a full ring along the inner arc surface of the outer lining structure. The steel bar connectors are used to fix the monitoring equipment and auxiliary cable equipment, and to connect the steel bars of the cast-in-place load-bearing member to the outer lining structure to form a grounding connection path.

4. The structure according to claim 1, characterized in that, The prefabricated load-bearing component is a prefabricated "U"-shaped component, which is installed on the lower inner side of the outer lining structure; The cast-in-place load-bearing component is a cast-in-place "arc" shaped plate, which is set along the inner arc surface of the outer lining structure; The precast load-bearing components and the cast-in-place load-bearing components together form the support structure of the power transmission equipment.

5. The structure according to claim 4, characterized in that, The precast "U"-shaped component has a connecting structure on its outer side for connecting with the cast-in-place "arc"-shaped slab. The cast-in-place "arc"-shaped slab is connected to the outer lining structure by means of rebar installation. The filling connecting material is densely filled in the gap between the precast "U"-shaped component and the outer lining structure.

6. The structure according to claim 1, characterized in that, The prefabricated load-bearing component includes a top slab, two side walls located below the top slab, and a bottom slab connecting the bottom of the two side walls; The bottom surface of the base plate is provided with multiple bottom convex surfaces, which are used to level the posture between the prefabricated load-bearing component and the inner arc surface of the outer lining structure. The outer sides of the two side walls are respectively provided with corbels, and an assembly auxiliary device is arranged below the corbels. The corbels and the assembly auxiliary device are used to assist in the hoisting and positioning assembly of the prefabricated load-bearing components. The base plate has through grouting holes, which are used to inject the filling and connecting material into the gap between the bottom of the precast bearing member and the outer lining structure. The surface of the top plate is provided with longitudinal bolt holes for auxiliary positioning or hoisting, and the joint between two adjacent prefabricated load-bearing components is a flat joint and is sealed with fireproof sealant.

7. The structure according to claim 1, characterized in that, The equipment passage space is a GIL equipment passage space, which is located in the upper area of ​​the cross-river pipe gallery. The reserved cable space, the maintenance passage space, and the collection space are located in the lower area of ​​the cross-river pipe gallery, so that the cross-river pipe gallery can simultaneously accommodate GIL equipment passage, long-term cable laying, maintenance operations, and fault gas collection.

8. The structure according to claim 7, characterized in that, The maintenance passage space is partially equipped with a cabinet installation area. The reserved cable space is separated from the collection space. The collection space is located in a lower position suitable for collecting leaked SF6 gas.

9. The structure according to claim 1, characterized in that, The inner layer internal structure also includes a leveling layer, a backfill layer, a drainage ditch, a waterproof layer, and a protective cover structure covering the drainage ditch, all located around the track structure or the combined load-bearing structure.

10. The structure according to claim 9, characterized in that, The filling and connecting material is mortar or fine stone concrete, the leveling layer is a concrete sealing and curing surface layer, the backfill layer is a plain concrete backfill layer, the waterproof layer is a polymer cement waterproof mortar layer applied to the surface of the drainage ditch, and the protective cover structure is a steel grating.

11. A construction method for GIL (Gas Infrared) river-crossing utility tunnels, applicable to the structure described in any one of claims 1-10, characterized in that, Includes the following steps: S1. Construct an outer lining structure to form the outer bearing boundary of the pipe gallery, and pre-embed multiple pre-embedded connection structures on the inner arc surface of the outer lining structure. S2. A cast-in-place track structure is placed inside the lower part of the outer lining structure to serve as the foundation for leveling the base and installing power transmission equipment. S3. The prefabricated load-bearing components are hoisted and installed on the track structure, and filling connection material is provided in the gap between the prefabricated load-bearing components and the outer lining structure; S4. Cast-in-place load-bearing components are provided on both sides of the precast load-bearing components and between the inner arc surfaces of the outer lining structure, and the cast-in-place load-bearing components are connected to the outer lining structure and the precast load-bearing components to form an integral load-bearing frame by means of rebar installation and the pre-embedded connection structure. S5. Divide the internal space of the cross-river utility tunnel into functional spaces, and set up equipment passage space, reserved cable space, maintenance passage space and collection space in the upper and lower sections.

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