Spatial flyover crossing hydraulic tunnel full-tunnel-section composite blocking structure and method

Abstract

The invention belongs to the technical field of hydraulic tunnel plugging structures in water conservancy and hydropower engineering, and particularly discloses a space vertical crossing hydraulic tunnel full-tunnel-section composite plugging structure and method which are used for conducting permanent full-tunnel-section plugging on a lower hydraulic tunnel spatially crossing an upper tunnel. Along the hole axis direction of the lower hydraulic tunnel from inside to outside, the lower hydraulic tunnel comprises a plugging body structure arranged at the inner end of the lower hydraulic tunnel; the concrete backfill structure is arranged in a space intersection area of the lower hydraulic tunnel and the upper tunnel; the mold bag rock ballast backfilling structure is arranged between the plugging body structure and the concrete backfilling structure, and / or is arranged between the concrete backfilling structure and a hole opening of the lower hydraulic tunnel; and the hole retaining wall structure is arranged at the hole of the lower hydraulic tunnel. According to the invention, the whole tunnel section of the tunnel can be blocked.

Description

Technical Field

[0001] This invention relates to the field of hydraulic tunnel sealing structure technology in water conservancy and hydropower engineering, specifically to a composite sealing structure and method for the entire section of a spatially intersecting hydraulic tunnel. Background Technology

[0002] With the rapid development of water conservancy and hydropower projects in my country, more and more water conservancy and hydropower projects are being built in deep mountains and canyons. In order to meet the requirements of different elevations and functions (such as diversion tunnels, flood discharge tunnels, water diversion tunnels, and traffic tunnels) in combination with the overall project layout, it is often necessary to arrange some underground cavern systems. This results in the situation where hydraulic tunnels intersect with each other in space. Moreover, the tunnels are basically connected to the reservoir area. The tunnel structure will have to withstand the high water head pressure of the reservoir in the future. In order to ensure the safe and reliable operation of the project, it is necessary to safely, reliably and permanently seal the entire tunnel section.

[0003] In the sealing of hydraulic tunnels, the common practice is to seal a section of the diversion tunnel at the location of the dam curtain line, which can meet the needs of the project operation and eliminate the need for full tunnel sealing, thus saving on project investment.

[0004] For hydraulic tunnels with spatial intersections, in order to ensure the safe operation of the upper and lower tunnels, it is necessary to seal the entire lower tunnel section. There are two common methods: one is to seal the entire tunnel section with concrete and carry out consolidation grouting, backfill grouting and joint grouting. This method has a high investment cost. Secondly, partial concrete sealing is used, employing concrete sealing bodies, consolidation grouting, backfill grouting, and joint grouting to meet the high water level water-blocking requirements. The remaining tunnel sections are backfilled with rockfill and grouted with cement, filling the entire tunnel with a dense chamber. Finally, the tunnel entrance is sealed with a concrete retaining wall. This method of rockfill backfilling is more difficult to construct, as it is impossible to backfill and pile it into a vertical surface. As a result, the rockfill at the top of the tunnel is not completely backfilled, and it must be completely backfilled with cement grout. Not only is it difficult to guarantee the density, but the grout volume is also large, and the cement grouting investment is high. At the same time, the use of rockfill backfilling in the three-dimensional intersection with the upper tunnel space poses a certain risk of settlement and deformation over long-term operation. Under the action of high external water pressure, the tunnel roof may collapse, which will affect the normal operation of the upper hydraulic tunnel. Summary of the Invention

[0005] This invention provides a composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel, with the aim of achieving full-section sealing of the tunnel.

[0006] This invention is achieved through the following technical solution: a composite sealing structure for the entire section of a spatially intersecting hydraulic tunnel, used for permanently sealing the entire section of a lower hydraulic tunnel that spatially intersects with an upper tunnel, comprising, from the inside to the outside, the following components along the tunnel axis of the lower hydraulic tunnel:

[0007] The sealing structure is located at the inner end of the lower hydraulic tunnel;

[0008] A concrete backfill structure is provided in the space where the lower hydraulic tunnel and the upper tunnel intersect.

[0009] A geotextile bag backfill structure is disposed between the sealing structure and the concrete backfill structure, and / or between the concrete backfill structure and the entrance of the lower hydraulic tunnel; and,

[0010] The portal retaining wall structure is installed at the portal of the lower hydraulic tunnel.

[0011] Furthermore, the sealing structure is a structure formed by casting micro-expansion concrete, and its shape is consistent with the tunnel cross-section.

[0012] Furthermore, the concrete backfill structure extends to both sides along the axis of the lower hydraulic tunnel, centered on the vertical projection of the intersection point of the upper tunnel and the lower hydraulic tunnel, with an extension length on each side. Where D is the excavation diameter or the inner diameter after lining of the upper tunnel.

[0013] Furthermore, the concrete backfill structure is backfilled with normal concrete across the entire cross-section.

[0014] Furthermore, the geotextile bag backfill structure is formed by stacking geotextile bags filled with stone inside the hole; the geotextile bags are made of high-strength woven geotextile.

[0015] Furthermore, a grouting pipe is pre-embedded in the top of the lower hydraulic tunnel, and a cement layer is formed by filling the gap between the formwork bag and the tunnel wall through the grouting pipe.

[0016] Furthermore, the grouting pipeline includes a main grouting pipeline and grouting branch pipelines. Multiple grouting branch pipelines are symmetrically arranged in the top area along the tunnel axis. Each grouting branch pipeline is provided with a grout outlet, and all of the multiple grouting branch pipelines are connected to the main grouting pipeline.

[0017] Furthermore, the retaining wall structure at the opening is formed by normal concrete pouring, and the wall of the retaining wall structure is embedded in the stable rock or soil surrounding the opening.

[0018] Furthermore, continuous exhaust grooves are symmetrically embedded on both sides of the center line of the top arch of the sealing structure, and exhaust pipes are connected to the exhaust grooves, with one end of the exhaust pipes leading out to the outside of the sealing structure.

[0019] A composite sealing method for the entire tunnel section of a spatially intersecting hydraulic tunnel includes the following steps:

[0020] At the inner end of the lower hydraulic tunnel that needs to be permanently sealed, a sealing structure is constructed. Before pouring the sealing structure, the surrounding rock of the sealing section is consolidated and grouted. After pouring, the top area is backfilled and grouted, and the joints between the sidewalls and the top arch and the surrounding rock are grouted.

[0021] In the area where the lower hydraulic tunnel and the upper tunnel intersect, a concrete backfill structure is constructed. After the backfill concrete is poured, the top area of ​​the concrete backfill structure is backfilled and grouted.

[0022] Between the sealing structure and the concrete backfill structure, and / or between the concrete backfill structure and the entrance of the lower hydraulic tunnel, a manhole bag gravel backfill structure is constructed. The specific steps include: stacking manhole bags filled with gravel inside the tunnel, and filling the gap between the manhole bags and the tunnel wall with grout through pre-embedded grouting pipes.

[0023] At the entrance of the lower hydraulic tunnel, a retaining wall structure was constructed.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. Significant economic benefits

[0026] (1) Cost savings: Compared with the traditional "full tunnel section concrete sealing", this scheme significantly reduces the amount of expensive C25 micro-expansion concrete used, which is only used in the key permanent water-retaining section. The remaining tunnel sections use relatively inexpensive C20 normal concrete and formwork bag stone, which directly reduces material costs.

[0027] (2) Controllable grouting volume: Traditional stone backfilling cannot fill the top completely, requiring large-scale and uncertain cavity grouting, resulting in huge cement consumption. This scheme uses manhole bags for placement, mainly because the tunnel shape is a city gate or horseshoe-shaped cross section, and there are gaps between the manhole bags and the tunnel wall only at the locations where the tunnel wall shape changes. Therefore, the grouting is controllable, the grouting volume is small, which can effectively avoid the waste of mud and further save on project investment.

[0028] 2. Excellent construction benefits

[0029] (1) Reduced construction difficulty: The precast bagged stone chips can be produced and stacked in a mechanized and standardized manner, which solves the construction problems of traditional stone chip backfilling, which is difficult to compact and cannot form a vertical surface, and greatly improves backfilling efficiency and compaction.

[0030] (2) Ensuring construction quality: Segmented treatment and targeted grouting (consolidation, backfilling, joint and gap grouting) ensured the quality of each sealing section. The geotextile stone slag section was pressure grouted through pre-embedded pipes, which could effectively fill the gaps and the density was much higher than that of traditional loose stone slag grouting.

[0031] (3) Clear process and clear quality control points: The structure of the scheme is clearly hierarchical (permanent structure, intersection section, stone rubble section, retaining wall), and the quality standards and inspection methods of each process are clear, which is conducive to construction management and whole-process quality control.

[0032] 3. Reliable safety benefits

[0033] (1) Completely eliminate long-term operational risks: C20 concrete is used for overall backfilling within the key influence range of the spatial three-dimensional intersection (3 to 5 times the tunnel diameter), forming a solid "support column". This fundamentally eliminates the risk of settlement and collapse that may occur in this area with traditional stone backfilling, providing the most reliable guarantee for the long-term, safe and stable operation of the upper water diversion tunnel.

[0034] (2) Water barrier safety is guaranteed: The permanent concrete sealing section is specially designed for high external water pressure and is supplemented by systematic grouting treatment to ensure the reliability and durability of the water barrier structure and meet the core safety requirements of reservoir water storage.

[0035] (3) High overall stability: The entire tunnel section is densely filled with different materials and forms an integral whole with the surrounding rock through grouting, which improves the overall stability of the mountain in this part. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0037] Figure 1 This is a schematic diagram of the plan layout of an embodiment of a composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to the present invention;

[0038] Figure 2 This is a longitudinal section schematic diagram of an embodiment of a composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to the present invention;

[0039] Figure 3 This is a cross-sectional view of the membrane bag stone backfilling and stacking in an embodiment of a composite sealing structure for a spatially intersecting hydraulic tunnel of the present invention.

[0040] Figure 4 This is a longitudinal section view of the consolidation and grouting arrangement of the sealing body structure in an embodiment of a composite sealing structure for a spatially intersecting hydraulic tunnel of the present invention.

[0041] Figure 5 for Figure 4 Sectional view at point 1-1;

[0042] Figure 6 for Figure 4 This is a sectional view at point 2-2;

[0043] Figure 7 This is a longitudinal section view of the backfill grouting arrangement of the sealing body structure in an embodiment of a spatial three-dimensional intersecting composite sealing structure for a hydraulic tunnel of the present invention.

[0044] Figure 8 for Figure 7 Sectional view at point 3-3;

[0045] Figure 9 for Figure 7 Sectional view at point 4-4;

[0046] Figure 10 This is a longitudinal section view of the joint grouting arrangement of the sealing body structure in an embodiment of a composite sealing structure for a spatially intersecting hydraulic tunnel of the present invention.

[0047] Figure 11 for Figure 10 Sectional view at point 5-5;

[0048] Figure 12 This is a longitudinal section view of the backfill grouting arrangement in the concrete backfill structure of an embodiment of a composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to the present invention.

[0049] The attached diagram shows the markings and corresponding component names:

[0050] 1. Retaining wall structure at the opening; 2. Backfill structure with stone bags; 201. Grout outlet; 202. Grouting branch road; 203. Grouting main road;

[0051] 3. Concrete backfill structure; 301. Backfill I grouting pipeline; 302. Backfill II grouting pipeline; 303. Backfill venting pipeline;

[0052] 4. Grouting hole 401, primary grouting pipeline of the sealing body 402, secondary grouting pipeline of the sealing body 403, venting pipeline of the sealing body 404, venting groove 405, venting pipe 406, grout outlet of the pipeline 407, grouting riser pipe 408, grout distribution pipe 409, grout inlet pipe 410, grout return pipe 411. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0054] This invention belongs to the technical field of hydraulic tunnel sealing structure in water conservancy and hydropower engineering. It is applicable to the sealing of the entire section of hydraulic tunnels that are connected to reservoirs, need to bear high external water pressure, and intersect with the space of the upper tunnel. It is especially applicable to the permanent sealing of temporary tunnels such as construction adits and diversion tunnels in reservoir areas, or other tunnel sealing projects that need to be permanently abandoned due to functional changes and have spatial intersections.

[0055] As one embodiment of this application, such as Figures 1-2 As shown, this embodiment provides a composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel, used for the permanent sealing of the entire tunnel section of a lower hydraulic tunnel that spatially intersects with an upper tunnel.

[0056] This embodiment of a composite sealing structure for a spatially intersecting hydraulic tunnel consists of four parts: a permanent concrete sealing structure 4, a spatially intersecting concrete backfill structure 3, a geotextile bag and gravel backfill structure 2, and a tunnel entrance retaining wall structure 1. Its plan layout is shown in the attached diagram. Figure 1 Specifically, it is a construction adit for a venting tunnel, located within the reservoir area. Approximately 30 meters above the construction adit, a water diversion and power generation tunnel is located. Figure 2 As shown, to ensure the long-term safety of the reservoir's water storage and the upper water diversion and power generation tunnel, the entire construction adit of this spatially intersecting tunnel is sealed off. Specifically, in this embodiment, along the tunnel axis of the lower hydraulic tunnel from the inside out, it includes:

[0057] The sealing structure 4 is located at the inner end of the lower hydraulic tunnel, adjacent to the venting tunnel, and serves as the main water barrier. Its length must be determined through anti-sliding stability analysis to ensure a sufficient safety factor under the design external water pressure. In this embodiment, the sealing structure 4 is a structure formed by full-section casting of C25 micro-expansion concrete, with a shape consistent with the tunnel cross-section.

[0058] The concrete backfill structure 3 is located at the spatial intersection of the lower hydraulic tunnel (construction adit) and the upper tunnel (water diversion and power generation tunnel). Specifically, in this embodiment, the concrete backfill structure 3 extends to both sides along the axis of the lower hydraulic tunnel, with the vertical projection of the intersection point of the upper tunnel and the lower hydraulic tunnel as the center. The extension length on each side is... Where D is the excavation diameter or the inner diameter after lining of the upper tunnel, this range is the stress disturbance and stability weak zone; in this embodiment, the concrete backfill structure 3 uses C20 normal concrete for full-section backfilling, providing uniform and solid support to prevent the upper tunnel floor slab from deforming or being damaged due to the lower cavity.

[0059] The geotextile bag backfill structure 2 is set between the sealing structure 4 and the concrete backfill structure 3, and / or between the concrete backfill structure 3 and the entrance of the lower hydraulic tunnel. In this embodiment, the geotextile bag backfill structure 2 is arranged between the permanent sealing structure 4 and the cross section concrete backfill structure 3, and between the cross section concrete backfill structure 3 and the entrance retaining wall structure 1.

[0060] like Figure 3 As shown, the geotextile bag backfill structure 2 in this embodiment is formed by stacking geotextile bags filled with stone aggregate inside the tunnel. The geotextile bags are made of high-strength woven geotextile, requiring high tensile strength (≥30kN / m), high puncture resistance, good permeability, and durability. The dimensions of a single filled geotextile bag are customized according to the tunnel cross-section, typically a cuboid with a length of 2.0–3.0m, a width of 1.0–1.5m, and a height of 0.5–1.0m, to facilitate handling and stacking. The stone aggregate should be clean, well-graded, and the maximum particle size should not exceed 1 / 2 the thickness of the geotextile bag. After the geotextile bags are filled with stone aggregate, they are stacked in layers and staggered in the tunnel, similar to bricklaying, to ensure overall compactness and stability.

[0061] as well as,

[0062] The portal retaining wall structure 1 is installed at the portal of the lower hydraulic tunnel. In this embodiment, the portal retaining wall structure 1 is located on the outermost side of the tunnel portal. It can permanently seal the portal, prevent rainwater from entering, and beautify the environment. It is the last barrier of the composite sealing structure. In this embodiment, the portal retaining wall structure 1 is formed by pouring C20 normal concrete with a thickness of 1.0m to 1.5m. The specific thickness can be determined according to the portal size and possible surface water pressure. The wall of the portal retaining wall structure 1 is embedded in the stable rock or soil around the portal. In this embodiment, the wall should be embedded in the stable rock or soil around the portal by at least 0.5m.

[0063] In one embodiment, because tunnel profiles are commonly arch-shaped or horseshoe-shaped, triangular or arched gaps may form at the top when the formwork bags are stacked. Therefore, cement grouting is required to fill these gaps densely. Figure 3 As shown, a grouting pipeline is pre-embedded in the top of the lower hydraulic tunnel. The grouting pipeline is made of galvanized steel pipe. A cement layer is formed by filling the gap between the formwork bag and the tunnel wall through the grouting pipeline. Specifically, in this embodiment, the grouting pipeline includes a main grouting pipeline 203 and grouting branch pipelines 202. Five grouting branch pipelines 202 are symmetrically arranged within a 180° range in the top area along the tunnel axis. Each grouting branch pipeline 202 is provided with a grout outlet 201. All five grouting branch pipelines 202 are connected to the main grouting pipeline 203. In this embodiment, the grouting pressure is not less than 1.5 times the water-blocking pressure. Cement grout is used for grouting, and the water-cement ratio of the grout is three levels: 2:1, 1:1, and 0.6:1 (or 0.5:1).

[0064] In one embodiment, such as Figure 10 and Figure 11 As shown, in this embodiment, continuous and elongated exhaust grooves 405 are symmetrically embedded on both sides of the center line of the top arch of the sealing body structure 4. An exhaust pipe 406 is connected to the exhaust groove 405, and one end of the exhaust pipe 406 is led out to the outside of the sealing body structure 4.

[0065] In this embodiment, the exhaust channel 405 is formed by a continuous angle steel embedded in the top arch. A cavity is formed between the back of the angle steel and the hole wall, thus forming the exhaust channel 405 structure. In this embodiment, the angle steel is ∠75×75×6mm. Vertical exhaust pipes 406 (DN50 galvanized steel pipes) are led out from each angle steel at intervals of 15 to 20m, and finally converge to the horizontal main pipe (DN80 galvanized steel pipe) and lead to the outside of the sealing structure 4, serving as the exhaust channel channel.

[0066] In another embodiment, this embodiment discloses a composite sealing method for the entire tunnel section of a spatially intersecting hydraulic tunnel, including the following steps:

[0067] At the inner end of the lower hydraulic tunnel requiring permanent sealing, a sealing structure 4 is constructed. In this embodiment, before pouring the sealing structure 4, consolidation grouting is performed on the surrounding rock of the sealing section to strengthen the loose surrounding rock around the sealing body, improve the overall integrity of the bearing capacity surrounding rock, etc., in conjunction with... Figure 4 As shown, during consolidation grouting, multiple rows of grouting holes 401 are arranged along the axis of the tunnel. In this embodiment, each row has 8 grouting holes 401, with a row spacing of 3m and a depth of 6m into the bedrock. Figure 5 and Figure 6 As shown, the eight grouting holes 401 in each row are arranged in a quincunx pattern, that is, distributed along the circumference of the tunnel, and the multiple grouting holes 401 in adjacent rows are staggered to avoid interference. In this embodiment, the grouting pressure for consolidation grouting is 0.6-0.8 MPa, and the tunnel deformation value is required to not exceed 200 μm. The specific value can be determined and adjusted according to the on-site grouting test. Cement grout is used for injection, and the water-cement ratio of the grout is adopted at four levels: 3:1, 2:1, 1:1, and 0.5:1. After grouting, the permeability q ≤ 5 Lu.

[0068] like Figure 7 , Figure 8 and Figure 9As shown, after pouring, backfilling and grouting are performed on the top area. Specifically, 3 days after the concrete pouring of the sealing structure 4 is completed, backfilling and grouting are performed on the top 120° area of ​​the sealing section to fill any gaps that may have been created during concrete pouring. In this embodiment, the backfilling and grouting of the sealing body is carried out in two sequences, namely, Sequence I and Sequence II. Specifically, in this implementation, it is completed through pre-embedded sealing body primary grouting pipes 402 and secondary grouting pipes 403 (both Φ25mm galvanized steel pipes). Multiple rows of sealing body primary grouting pipes 402 and secondary grouting pipes 403 are arranged, with intervals of 2.5–3.5m between rows. Figure 9 As shown, in this embodiment, the sealing body I grouting pipeline 402 has three branches arranged in each row within a 120° range, and they are arranged in a quincunx pattern, as shown below. Figure 8 As shown, in this embodiment, the sealing body secondary grouting pipeline 403 has three pipelines arranged in each row within a 90° range, and they are arranged in a quincunx pattern.

[0069] like Figure 7 As shown, in this embodiment, a sealing body exhaust pipe 404 is buried at the top of the sealing body structure 4. Vertical sealing body exhaust pipes 404 (DN50 galvanized steel pipes) are arranged at intervals of 5-10m along the tunnel axis, and finally converge to the horizontal main pipe (DN80 galvanized steel pipe) and lead to the outside of the sealing body structure 4 to discharge air during grouting. In this embodiment, the grouting pressure during backfilling grouting of the sealing body section is 0.3-0.5 MPa, and the return grouting pressure is not less than 0.2-0.35 MPa. Expansive cement mortar is used for grouting, and the water-cement ratio of the grout is 1:1 and 0.5:1.

[0070] Grouting is performed on the joints between the sidewalls and the arch and the surrounding rock. After the concrete of the sealing body cools to a stable temperature (or reaches an age of more than 28 days), grouting is performed on the sidewalls and arch of the sealing structure 4 to ensure that the joints do not leak under high water pressure. Specifically: Figure 10 , Figure 11 As shown, joint grouting is carried out through a pre-embedded joint grouting pipeline (Φ25mm galvanized steel pipe). The joint grouting pipeline includes a riser pipe 408, a distribution pipe 409, an inlet pipe 410, a return pipe 411, and a grout outlet 407. Figure 10 As shown, the grout outlet 407 of the pipeline is arranged in multiple rows along the longitudinal direction of the sealing structure 4 at a row spacing of 2m. The grout inlet pipe 410 is responsible for receiving fresh grout and conveying it forward to the inlet of each grout riser pipe 408. The grout riser pipe 408 lifts the horizontally conveyed grout upward and conveys it to the grout distribution pipe 409, and then injects it into the joint cavity through the grout outlet 407 of the pipeline. The grout return pipe 411 is responsible for recovering the grout from the joint area or the end of the grout riser pipe 408 system and making it flow back.

[0071] In this embodiment, when grouting the joints of the sealing body, the grouting pressure is not less than 1.5 times the water-blocking pressure. Cement grout is used for grouting, and the water-cement ratio of the grout is 2:1, 1:1, or 0.6:1 (or 0.5:1) at three levels.

[0072] In the area where the lower hydraulic tunnel and the upper tunnel intersect, a concrete backfill structure 3 is constructed. After the backfill concrete is poured, the top area of ​​the concrete backfill structure 3 is backfilled and grouted. Specifically, 3 days after the backfill concrete is poured, the top 120° area of ​​the backfill concrete is backfilled and grouted to fill the gaps that may have been generated at the top during the concrete pouring. The backfilling and grouting method is the same as that of the backfilling and grouting method of the sealing structure section.

[0073] like Figure 12 As shown, the backfilling grouting of the concrete backfill structure 3 is carried out in two sequences, namely, Sequence I and Sequence II. Specifically, in this embodiment, it is completed by pre-embedded backfilling grouting pipes 301 and 302 (Φ25mm galvanized steel pipes). Both backfilling grouting pipes 301 and 302 are arranged in multiple rows, and the multiple rows of backfilling grouting pipes 301 and 302 are arranged at intervals with a row spacing of 2.5 to 3.5m. In this embodiment, backfilling grouting pipes 301 have three branches per row within a 120° range, and are arranged in a quincunx pattern. In this embodiment, backfilling grouting pipes 302 have three branches per row within a 90° range, and are arranged in a quincunx pattern.

[0074] like Figure 12 As shown, in this embodiment, a backfill venting pipe 303 is buried at the top of the sealing structure 4. Specifically, vertical backfill venting pipes 303 (DN50 galvanized steel pipes) are arranged at intervals of 5 to 10 m along the tunnel axis, and finally converge to a horizontal main pipe (DN80 galvanized steel pipe) and lead to the outside of the concrete backfill structure 3 to expel air during grouting. In this embodiment, the grouting pressure during backfilling grouting in the concrete backfill structure 3 is 0.3 to 0.5 MPa, and the backfill pressure is not lower than 0.2 to 0.35 MPa. Expansive cement mortar is used for grouting, and the water-cement ratio of the grout is 1:1 and 0.5:1.

[0075] Between the sealing structure 4 and the concrete backfill structure 3, and / or between the concrete backfill structure 3 and the entrance of the lower hydraulic tunnel, a manhole bag and gravel backfill structure 2 is constructed. Specific steps include: stacking manhole bags filled with gravel inside the tunnel, and filling the gap between the manhole bags and the tunnel wall with grout through pre-embedded grouting pipes. In this embodiment, because the tunnel profile is commonly a city gate shape or horseshoe shape, triangular or arched gaps will form at the top when the manhole bags are stacked. Therefore, cement grouting is used to ensure dense filling. In this embodiment, the grouting pressure for filling the gap between the manhole bags and the tunnel wall is not less than 1.5 times the water-retaining pressure. Cement grout is used, with a water-cement ratio of 2:1, 1:1, or 0.6:1 (or 0.5:1) at three levels.

[0076] At the entrance of the lower hydraulic tunnel, a retaining wall structure 1 was constructed.

[0077] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel, used for the permanent sealing of the entire tunnel section of a lower hydraulic tunnel that spatially intersects with an upper tunnel, characterized in that, Along the tunnel axis of the lower hydraulic tunnel, from the inside out, it includes the following: The sealing structure is located at the inner end of the lower hydraulic tunnel; A concrete backfill structure is provided in the space where the lower hydraulic tunnel and the upper tunnel intersect; A geotextile bag backfill structure is disposed between the sealing structure and the concrete backfill structure, and / or between the concrete backfill structure and the entrance of the lower hydraulic tunnel; and, The portal retaining wall structure is installed at the portal of the lower hydraulic tunnel.

2. The composite sealing structure for the entire section of a spatially intersecting hydraulic tunnel according to claim 1, characterized in that, The sealing structure is a structure formed by casting micro-expansion concrete, and its shape is consistent with the tunnel cross-section.

3. A composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 1 or 2, characterized in that, The concrete backfill structure extends to both sides along the axis of the lower hydraulic tunnel, centered on the vertical projection of the intersection point of the upper tunnel and the lower hydraulic tunnel. The extension length on each side is [length missing]. Where D is the excavation diameter or the inner diameter after lining of the upper tunnel.

4. The composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 3, characterized in that, The concrete backfill structure is backfilled with normal concrete across the entire cross section.

5. The composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 1, characterized in that, The geotextile bag backfill structure is formed by stacking geotextile bags filled with stone inside the hole; the geotextile bags are made of high-strength woven geotextile.

6. The composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 5, characterized in that, The top of the lower hydraulic tunnel is pre-embedded with grouting pipes, which fill the gap between the formwork bag and the tunnel wall to form a cement layer.

7. A composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 6, characterized in that, The grouting pipeline includes a main grouting pipeline and grouting branch pipelines. Multiple grouting branch pipelines are symmetrically arranged in the top area along the tunnel axis. Each grouting branch pipeline is provided with a grout outlet, and all of the multiple grouting branch pipelines are connected to the main grouting pipeline.

8. The composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 1, characterized in that, The retaining wall structure at the opening is formed by normal concrete pouring, and the wall of the retaining wall structure is embedded in the stable rock or soil around the opening.

9. A composite sealing structure for the entire tunnel section of a spatially intersecting hydraulic tunnel according to claim 1, characterized in that, A continuous, elongated exhaust groove is symmetrically embedded on both sides of the center line of the top arch of the sealing structure. An exhaust pipe is connected to the exhaust groove, and one end of the exhaust pipe leads out to the outside of the sealing structure.

10. A composite sealing method for the entire section of a spatially intersecting hydraulic tunnel, characterized in that, Includes the following steps: At the inner end of the lower hydraulic tunnel that needs to be permanently sealed, a sealing structure is constructed. Before pouring the sealing structure, the surrounding rock of the sealing section is consolidated and grouted. After pouring, the top area is backfilled and grouted, and the joints between the sidewalls and the top arch and the surrounding rock are grouted. In the area where the lower hydraulic tunnel and the upper tunnel intersect, a concrete backfill structure is constructed. After the backfill concrete is poured, the top area of ​​the concrete backfill structure is backfilled and grouted. Between the sealing structure and the concrete backfill structure, and / or between the concrete backfill structure and the entrance of the lower hydraulic tunnel, a manhole bag gravel backfill structure is constructed. The specific steps include: stacking manhole bags filled with gravel inside the tunnel, and filling the gap between the manhole bags and the tunnel wall with grout through pre-embedded grouting pipes. At the entrance of the lower hydraulic tunnel, a retaining wall structure was constructed.

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