Blocking construction method and blocking structure for dam-passing traffic tunnel

Abstract

The invention relates to the technical field of tunnel blocking, in particular to a dam-crossing traffic tunnel blocking construction method and a blocking structure. The method comprises the steps that S1, a concrete blank cap is constructed at an upstream inlet of a to-be-blocked tunnel, and backfilling and consolidation grouting are conducted on the contact position of a blank cap body and rock around the tunnel; s2, dam water storage; and S3, in the dam water storage process or after dam water storage, plugging body construction is conducted in the tunnel. The anti-shear capacity of the blank cap structure is fully utilized, the overall engineering amount of the plugging body is reduced, the construction period needed by dam water storage can be greatly shortened, the arrangement of the two plugging structures is safer and more reliable, and the construction period of tunnel plugging engineering is shortened on the whole.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel blocking, and in particular to a blocking construction method and a blocking structure for a dam-crossing traffic tunnel. Background Art

[0002] In the construction of water conservancy and hydropower projects, hydraulic tunnels are usually used. Hydraulic tunnels are temporary buildings, such as diversion tunnels, temporary dam traffic tunnels, geological exploration tunnels, construction branch tunnels, flood discharge tunnels, water diversion and power generation tunnels, etc. These temporary tunnels have certain safety hazards and generally need to be blocked. The blocking body will become an important part of the hydraulic structure and will bear the internal water pressure together with the surrounding rock or concrete. It is a permanent building. The engineering volume of the tunnel blocking body is not large, but because of its particularly important location, once there is a design omission or construction quality accident, it is generally difficult to make up for it.

[0003] The plugging body is usually arranged at a certain position in the middle section of the tunnel. Conventional plugging bodies are in the form of bottle stopper, short nail, column, arch, etc. The basic loads borne by the plugging body mainly include water pressure, seepage pressure, deadweight, seismic load and surrounding pressure. Under the action of water thrust, the plugging body has a tendency to be sheared along the periphery. From the form of the plugging body, it can be seen that the safety and stability of the plugging body mainly depends on the shear strength of the bonding surface between concrete and the surrounding rock. Therefore, the length of the plugging body is often designed to be longer.

[0004] In addition, considering that the excavation of the tunnel sealing body section will cause certain damage to the rock around the tunnel and the completed curtain grouting, it is necessary to carry out reinforcement curtain grouting; when pouring the sealing body, it is necessary to consider filling the cracks in the rock around the tunnel and the gaps between the concrete and the tunnel, and consolidation grouting and backfill grouting are required; when the sealing length does not meet the anti-friction resistance requirements, it is necessary to add anchor rods around the tunnel.

[0005] Therefore, conventional tunnel plugging bodies take more measures, and the plugging body is long, the overall construction cost is high, and the construction period is long. In actual engineering construction, the plugging body construction is generally in the later stage of the project, and will face the pressure of flood season and dam water storage acceptance. In addition to engineering safety and stability, saving engineering work and shortening construction period are also key issues that need to be paid attention to in the design and construction of tunnel plugging bodies.

[0006] Prior art CN110004878A discloses a method for using a dam water tunnel rapid plugging device, including: step 1, hoisting an empty steel bin into the water, aligning the outer side of the bottom plate of the empty steel bin with the water tunnel on the concrete dam body, and allowing the ball to enter the water tunnel under the action of the water flow, and further pulling the empty steel bin through a steel cable to align with the water tunnel on the concrete dam body, and the rubber sheet on the outer side of the bottom plate of the empty steel bin is in close contact with the concrete dam body under the action of the water flow; step 2, hoisting a rubber plug into the water, aligning it with the circular hole in the center of the bottom plate of the empty steel bin, and the rubber plug blocks the circular hole in the center of the bottom plate of the empty steel bin under the action of the water flow; step 3, taking out the ball after plugging is completed. The water tunnel can be plugged without draining the upstream water of the concrete dam body to the bottom of the water tunnel.

[0007] The above-mentioned prior art has many uncontrollable factors, such as water flow speed and direction, which lead to inconvenience in operation, and underwater operations cannot be directly observed, and the blocking effect is uncontrollable. Summary of the invention

[0008] In order to solve the technical problems of long construction period and high cost in the prior art for blocking a cross-dam traffic tunnel, the present invention provides a blocking construction method and a blocking structure for a cross-dam traffic tunnel.

[0009] To achieve the above object, the technical solution of the present invention is as follows:

[0010] In one aspect, the present invention provides a method for blocking a dam-crossing traffic tunnel, comprising:

[0011] S1. Construct a concrete cover at the upstream entrance of the tunnel to be blocked, and backfill and consolidate grouting are performed at the contact between the cover and the rock around the tunnel;

[0012] S2, dam water storage;

[0013] S3. During or after the dam is filled with water, the sealing body is constructed inside the tunnel.

[0014] Furthermore, the construction method of the cover specifically includes:

[0015] S101, water cut-off at the dam traffic tunnel;

[0016] S102, demolition of the arch frame and its accessories at the entrance;

[0017] S103, cleaning the rock wall at the cave entrance and the blocking section at the cave bottom. The sealing cover includes a front cover arranged outside the cave entrance and a door plug inside the cave, and a foundation trench is dug at the cave bottom at the front cover.

[0018] S104, formwork installation, steel bar binding, pre-buried grouting pipes; concrete pouring, and maintenance after pouring;

[0019] S105. Backfill grouting.

[0020] Furthermore, step S104 specifically includes: erecting a full-section mold on the inner side of the door plug, and tying the steel bars of the front cover and erecting the front cover mold at the connection between the front cover and the door plug; pouring concrete after pre-burying the grouting pipe, forming in three times, and setting a groove water stop on the construction joint surface, and the three forming steps are respectively:

[0021] The dimensions of the first pouring of the front cover foundation trench are trench depth 1.5m × front cover thickness 1.5m × front cover width 8.1m;

[0022] The second pouring of the door plug part and the front cover part at the same elevation;

[0023] The remaining part of the front cover is poured for the third time;

[0024] During the pouring process, cooling water pipes are arranged at the construction joint level in an S-shaped arrangement. Water cooling begins after the previous layer of concrete is poured until the concrete temperature drops to a stable temperature and meets the requirements for contact grouting.

[0025] Furthermore, the steel bar binding in step S104 specifically includes: the front cover of the blind cover is arranged with double-layer steel bars;

[0026] Among them, the reinforcement of the first layer of steel bars is: 85C25@100 in the horizontal direction and 80C25@100 in the vertical direction, and the reinforcement of the second layer section is: 43C25@200 in the horizontal direction and 40C25@200 in the vertical direction.

[0027] Furthermore, before pouring, consolidation grouting holes are excavated in the tunnel, and the consolidation grouting holes include several rows. From the tunnel entrance to the tunnel, the odd-numbered rows of consolidation grouting holes include first grouting holes arranged radially along the arch, second grouting holes arranged horizontally on the side wall of the tunnel, and third grouting holes arranged vertically below the tunnel. The number of first grouting holes is 4, and the four first grouting holes are symmetrically arranged on both sides of the tunnel, and the spacing between adjacent first grouting holes is 33.33°; the number of second grouting holes is 4, and the four second grouting holes are symmetrically arranged on both sides of the tunnel; the number of third grouting holes is 2, and the two third grouting holes are symmetrically arranged on both sides of the tunnel;

[0028] The even-numbered rows of consolidation grouting holes include fourth grouting holes distributed radially along the arch, fifth grouting holes horizontally arranged on the side wall of the tunnel and sixth grouting holes arranged below the tunnel. The number of fourth grouting holes is 3, and the three fourth grouting holes are symmetrically arranged on both sides of the tunnel; the number of fifth grouting holes is 4, and the four fifth grouting holes are symmetrically arranged on both sides of the tunnel; the number of sixth grouting holes is 3, one of the sixth grouting holes is vertically arranged on the center line below the tunnel, and the other two sixth grouting holes are symmetrically inclined on both sides below the tunnel.

[0029] Furthermore, in step S105, the backfill grouting is constructed by the buried pipe method, which specifically includes: placing the hole position, burying the grouting pipe and the grouting return pipe in the designated position on the top of the hole; inspecting the construction joints and concrete defects of the lining concrete, and processing the possible leakage parts; using the pure pressure grouting method for grouting construction, and sealing the hole after the grouting is completed.

[0030] Furthermore, the backfill grouting pressure is 0.2-0.3MPa.

[0031] Furthermore, under the set pressure, when the grouting amount of the grouting section is less than 1L / min, the grouting can be terminated by continuing to grout for 5 minutes.

[0032] Furthermore, step S3, performing plugging construction inside the tunnel, specifically includes:

[0033] S301, Phase I plugging: backfill the entire tunnel with concrete;

[0034] S302, Phase II plugging: A grouting corridor is set up downstream of the full-section concrete backfill section.

[0035] Furthermore, the first-phase plugging of step S301 is cast in two times using the step method, specifically including: the portion with a length of L on the upstream side of this plugging section is formed in one step with the whole section, pumped into the bin by a ground pump arranged at the hole entrance, and vibrated and compacted in layers by an inserted vibrator; then, a plugging section formwork is erected downstream of this plugging section, a concrete pump pipe is arranged in the middle of the plugging section along the arch, an exhaust pipe is arranged on the arch, concrete is pumped from low to high, and is vibrated and compacted in layers by an inserted vibrator; pumping can be stopped after slurry comes out of the exhaust pipe.

[0036] Furthermore, the size of the grouting gallery in step S302 is a 3m×3.5m city gate type.

[0037] Furthermore, the second-stage plugging of step S302 is constructed by a three-layer pouring method, which specifically includes:

[0038] The first layer is the bottom slab concrete pouring, the pouring height is 1m;

[0039] The second layer is the corridor side wall, with a pouring height of 2m;

[0040] The third layer is top supply, and the top supply concrete is delivered through the pump pipe outlet arranged at the top supply.

[0041] On the other hand, the present invention also provides a blocking structure for a cross-dam traffic tunnel, comprising a blind cover arranged at the upstream entrance of the tunnel and a blocking body inside the tunnel, the blind cover comprising a front cover and a door plug connected to the front cover, the front cover being arranged outside the entrance, the front cover covering the entrance and having an area larger than the entrance area; the door plug being arranged inside the hole at the entrance.

[0042] Furthermore, the width of the front cover is 1.5 m and the length of the door plug is 8 m.

[0043] Furthermore, the plugging body includes a solid part and a grouting gallery, the solid part is 21.5 m long, and the grouting gallery is 8.5 m long.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The blocking construction method and blocking structure of the cross-dam traffic tunnel provided by the present invention arrange a blind cover at the tunnel entrance. During the operation of the reservoir, the water pressure generated on the upstream side acts vertically on the blind cover cap, which makes the blind cover fit more closely with the upstream rock wall, which is beneficial to increase the blocking effect of the blind cover; the blind cover simultaneously utilizes the shear strength of the concrete cap and the shear strength of the concrete and the rock bonding surface on the perimeter to resist the upstream water pressure, and has a higher safety factor; the blind cover and the blocking body in the tunnel form a two-line blocking structure, which has higher reliability than the traditional one-line blocking structure.

[0046] After the construction of the sealing cover is completed, the dam can be filled with water, which greatly reduces the construction period required for the dam to be filled with water. At the same time, because the length of the plugging body in the tunnel can be shortened, the amount of concrete and grouting work in the plugging section is reduced, the overall construction work of the plugging structure of the present invention is less, the cost of the plugging project is reduced, and the construction period of the tunnel plugging project is shortened.

[0047] In addition to increasing the safety and stability of the project, the present invention is more suitable for situations where the dam water storage period is tight. It can achieve water storage conditions within a shorter period of time and has been verified by actual engineering cases, showing strong feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the blocking structure of the cross-dam traffic tunnel in Example 1.

[0049] Figure 2 This is a schematic diagram of the cover structure provided by the present invention.

[0050] Figure 3 This is a schematic diagram of the layers of the cover casting.

[0051] Figure 4 This is a cross-sectional view of the arrangement of cooling water pipes when the cover is cast.

[0052] Figure 5 It is a cross-sectional view of the arrangement of cooling water pipes when the cover is cast.

[0053] Figure 6 This is the reinforcement diagram for the front cover of the blind cover.

[0054] Figure 7 for Figure 6Cross-section view at AA in the middle.

[0055] Figure 8 for Figure 6 Cross-section view at the middle BB.

[0056] Fig. 9 This is the cross-sectional view of the cap consolidation grouting.

[0057] Fig.10 This is the cross-sectional arrangement diagram of odd-numbered rows of consolidation grouting holes.

[0058] Fig.11 This is the cross-sectional arrangement diagram of an even-numbered row of consolidation grouting holes.

[0059] Fig.12 This is the longitudinal section layout diagram for backfill grouting of the capping roof.

[0060] Fig.13 for Fig.12 Cross-section view at CC.

[0061] Fig.14 for Fig.12 Cross-sectional view at DD.

[0062] Fig.15 for Fig.12 Cross-sectional view at EE.

[0063] Fig.16 This is a cross-sectional view of the curtain grouting of the sealing body in the tunnel.

[0064] Fig.17 This is the cross-sectional layout diagram of the upstream row of curtain grouting for the sealing body in the tunnel.

[0065] Fig.18 This is the cross-sectional layout diagram of the curtain grouting downstream of the sealing body in the tunnel.

[0066] Description of reference numerals:

[0067] 1-sealing body, 2-front cover, 3-door plug, 4-cooling water pipe, 5-consolidation grouting hole. DETAILED DESCRIPTION

[0068] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the protection scope of the present invention.

[0069] It should be noted that, unless otherwise specifically stated, the relative arrangements of components and steps, and numerical expressions set forth in these embodiments should not be construed as limiting the scope of the present invention.

[0070] The following description of the exemplary embodiments is merely illustrative and is not intended to limit the present invention and its application or use in any sense. Techniques, methods and devices known to ordinary technicians in the relevant field may not be discussed in detail here, but where applicable, these techniques, methods and devices should be considered as part of this specification.

[0071] Embodiment 1

[0072] This embodiment provides a method for blocking a traffic tunnel across a dam. Figure 1 Taking the traffic tunnel across the dam as an example, the tunnel is blocked, specifically including:

[0073] S1. Construct a concrete cover at the upstream entrance of the tunnel to be blocked, and backfill and consolidate grouting are performed at the contact between the cover and the rock around the tunnel;

[0074] The blocking of the traffic tunnel across the dam is divided into two sections. The pile number of the dam body section is k0+150m~k0+180m, a total of 30m, and the cover section is k0+247m~k0+256.5m, a total of 9.5m.

[0075] The construction methods of the cover specifically include:

[0076] S101, water cut-off at the dam traffic tunnel;

[0077] S102, demolition of the arch frame and its accessories at the entrance;

[0078] S103, clean the rock wall at the cave entrance and remove the weathered part; clean the sealing section at the bottom of the cave, such as Figure 2 As shown, the cover includes a front cover arranged outside the hole and a door plug inside the hole, and a base groove is dug at the bottom of the hole at the front cover;

[0079] S104, formwork installation, steel bar binding, pre-buried grouting pipes; concrete pouring, and maintenance after pouring; specifically:

[0080] At K0+248.5, the full-section formwork is erected, and the reinforcement of the front cover and the front cover formwork are tied at K0+255; before pouring, consolidation grouting holes are excavated in the hole, such as Fig. 9 As shown, the consolidation grouting holes include several rows. Fig.10 As shown, from the tunnel entrance to the tunnel, the odd-numbered rows of consolidation grouting holes include first grouting holes radially arranged along the arch, second grouting holes horizontally arranged on the side wall of the tunnel, and third grouting holes vertically arranged below the tunnel. The number of first grouting holes is 4, and the four first grouting holes are symmetrically arranged on both sides of the tunnel, and the spacing between adjacent first grouting holes is 33.33°; the number of second grouting holes is 4, and the four second grouting holes are symmetrically arranged on both sides of the tunnel; the number of third grouting holes is 2, and the two third grouting holes are symmetrically arranged on both sides of the tunnel;

[0081] like Fig.11 As shown, the even-numbered rows of consolidation grouting holes include fourth grouting holes radially distributed along the arch, fifth grouting holes horizontally arranged on the side wall of the tunnel and sixth grouting holes arranged below the tunnel. The number of fourth grouting holes is 3, and the three fourth grouting holes are symmetrically arranged on both sides of the tunnel; the number of fifth grouting holes is 4, and the four fifth grouting holes are symmetrically arranged on both sides of the tunnel; the number of sixth grouting holes is 3, one of the sixth grouting holes is vertically arranged on the center line below the tunnel, and the other two sixth grouting holes are symmetrically inclined and arranged on both sides below the tunnel.

[0082] After the grouting pipe is pre-buried, concrete pouring is carried out. The concrete construction adopts commercial concrete truck pumping into the warehouse, and is formed in three steps. A groove is set at the construction joint level to stop water. The three steps of forming are:

[0083] The dimensions of the first pouring of the front cover foundation trench are trench depth 1.5m × front cover thickness 1.5m × front cover width 8.1m.

[0084] The second pouring is for the door plug part and the front cover part at the same elevation. The second pouring is layered pouring, which is divided into 4 layers. Figure 3 As shown, the first layer is 1.08m thick, the second layer is 1.5m thick, the third layer is 1.5m thick, and the fourth layer is 1.52m thick; the door stopper part is a city gate type, with dimensions of 5.6m high × 5.1m wide × 8.0m long, and the front cover part has dimensions of 1.5m thick × 5.6m high × 8.1m wide.

[0085] The remaining part of the front cover was poured for the third time, with dimensions of 1.5m thick × 1.5m high × 8.1m wide.

[0086] The formwork is made of ordinary wooden formwork; Φ48mm steel pipes are used for vertical and horizontal enclosures, and Φ12 steel bars are used for anchoring. Before installing the formwork, clean up the debris on the surface of the formwork.

[0087] The water stop plate of the traffic tunnel needs to be grooved with a depth of 25cm in the surrounding rock mass using a rock drill and the water stop plate buried. The working surface below the tunnel floor elevation of 2.0m does not need to be roughened by setting up a platform. For the working surface above 2.0m from the tunnel floor elevation (top side wall position), a simple working platform is set up to groove. After the groove is cut, the water stop plate is buried and concrete is poured.

[0088] During the pouring process, cooling water pipes are arranged at the construction joint level. The cooling water pipes are arranged in an S shape, such as Figure 4 and Figure 5 As shown, water cooling begins after the previous layer of concrete is poured until the concrete temperature drops to a stable temperature and meets the requirements for contact grouting.

[0089] Among them, Figure 6As shown in the figure, the front cover of the cover is arranged with double layers of steel bars; the first layer of steel bars is arranged with 85C25@100 in the horizontal direction and 80C25@100 in the vertical direction. Figure 7 The reinforcement of the second layer section is: 43C25@200 in the horizontal direction and 40C25@200 in the vertical direction. Figure 8 shown.

[0090] S105, backfill grouting; when the thickness of the concrete pouring reaches 70% of the design strength, grouting treatment is carried out as required, including: placing the hole position, burying the grouting pipe and the return grouting pipe into the designated position on the top of the hole, using a 1-inch plastic pipe as the grouting pipe and a 6-centimeter plastic pipe as the return grouting pipe.

[0091] like Figures 12 to 15 As shown, the backfill grouting pipeline includes the first-order backfill grouting pipeline and the second-order backfill grouting pipeline, and an exhaust pipeline is set. The construction joints and concrete defects of the lining concrete are checked, and the possible leakage parts are treated; the pure pressure grouting method is used for grouting construction, and the holes are sealed after the grouting is completed.

[0092] The backfill grouting pressure is 0.2-0.3MPa. When the grouting volume of the grouting section is less than 1L / min under the set pressure, the grouting can be terminated after 5 minutes of continuous grouting.

[0093] S2. Dam storage.

[0094] S3. During or after the dam is filled with water, the sealing body is constructed inside the tunnel.

[0095] like Figure 1 and Fig.16 As shown in the figure, the plugging body consists of two parts, one is the solid section of 20m (K0+160~K0+180) that passes through the rock section of the left bank 2# dam section from K0+150 to K0+180, and the other is the grouting gallery section of 10m (K0+150~K0+160); the specific construction methods include:

[0096] S301. Phase I plugging: backfill the tunnel with full-section concrete. Phase I plugging is a full-section plugging section (20m) with pile numbers K0+160 to K0+180. It is poured twice using the step method, including: the upstream side of this plugging section with a length of 2.5m is formed in one step with full section, using commercial concrete, which is pumped into the bin by a 60-type concrete delivery pump (ground pump) arranged at the tunnel entrance, and vibrated and compacted in layers by an inserted vibrator; then, a plugging section formwork is erected at K0+160 downstream of this plugging section, and a concrete pump pipe is arranged along the arch at K0+175, the middle position of the plugging section, and an exhaust pipe is arranged on the arch. The pumped concrete is pumped from low to high, and the inserted vibrator is vibrated and compacted in layers; the vibrating personnel enter from the manhole at K0+160. When there is insufficient space for the construction personnel to work, the construction personnel withdraw, the manhole is closed, and the concrete is compacted by pumping. The pumping can be stopped after the slurry comes out of the exhaust pipe.

[0097] S302, Phase II plugging: A grouting gallery is set up downstream of the full-section concrete backfill section. The size of the grouting gallery is 3m×3.5m city gate type; Phase II plugging is constructed using a three-layer pouring method, specifically including:

[0098] The first layer is the bottom slab concrete pouring, the pouring height is 1m;

[0099] The second layer is the corridor side wall, with a pouring height of 2m, and the concrete layered construction joints are roughened;

[0100] The third layer is top supply, and the top supply concrete is delivered through the pump pipe outlet arranged at the top supply.

[0101] The backfill grouting and contact grouting process of the plugging body in the cave adopts the construction process in the existing technology. After the backfill grouting and contact grouting, curtain grouting is carried out, such as Figures 16 to 18 As shown in the figure, the curtain grouting holes are arranged in 2 rows, and the grouting of the same row is carried out in 2 sequences. Fig.17 and Fig.18 shown.

[0102] Embodiment 2

[0103] This embodiment provides a blocking structure for a traffic tunnel across a dam, such as Figure 1 As shown, it includes a blind cover arranged at the upstream opening of the tunnel and a blocking body inside the tunnel, the blind cover includes a front cover and a door plug connected to the front cover, the front cover is arranged outside the opening, the front cover covers the opening and the area is larger than the opening area; the door plug is arranged in the hole at the opening.

[0104] The front cover is 1.5m wide and the door plug is 8m long. The plugging body includes a solid part and a grouting gallery, the solid part is 21.5m long and the grouting gallery is 8.5m long.

[0105] The above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, a person skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for blocking a dam traffic tunnel, characterized in that: include: S1. Construct a concrete cover at the upstream entrance of the tunnel to be blocked, and backfill and consolidate grouting are performed at the contact between the cover and the rock around the tunnel; S2, dam water storage; S3. During or after the dam is filled with water, the sealing body is constructed inside the tunnel.

2. The method for blocking construction of a cross-dam traffic tunnel according to claim 1, characterized in that: The construction methods of the cover specifically include: S101, water cut-off at the dam traffic tunnel; S102, demolition of the arch frame and its accessories at the entrance; S103, cleaning the rock wall at the cave entrance and the blocking section at the cave bottom. The sealing cover includes a front cover arranged outside the cave entrance and a door plug inside the cave, and a foundation trench is dug at the cave bottom at the front cover. S104, formwork installation, steel bar binding, pre-buried grouting pipes; concrete pouring, and maintenance after pouring; S105. Backfill grouting.

3. The method for blocking construction of a cross-dam traffic tunnel according to claim 2, characterized in that: Step S104 specifically includes: erecting a full-section mold on the inner side of the door plug, and tying the steel bars of the front cover and erecting the front cover mold at the connection between the front cover and the door plug; pouring concrete after pre-burying the grouting pipe, forming in three steps, and setting a groove to stop water on the construction joint surface, and the three steps of forming are respectively: The dimensions of the first pouring of the front cover foundation trench are trench depth 1.5m × front cover thickness 1.5m × front cover width 8.1m; The second pouring of the door plug part and the front cover part at the same elevation; The remaining part of the front cover is poured for the third time; During the pouring process, cooling water pipes are arranged at the construction joint level in an S-shaped arrangement. Water cooling begins after the previous layer of concrete is poured until the concrete temperature drops to a stable temperature and meets the requirements for contact grouting.

4. The method for blocking construction of a dam-crossing traffic tunnel according to claim 3 is characterized in that: The steel bar binding in step S104 specifically includes: the front cover of the blind cover is arranged with double layers of steel bars.

5. The method for blocking construction of a dam-crossing traffic tunnel according to claim 3 is characterized in that: Before pouring, consolidation grouting holes are excavated in the tunnel. The consolidation grouting holes include several rows. From the tunnel entrance to the tunnel, the odd-numbered rows of consolidation grouting holes include the first grouting holes arranged radially along the arch, the second grouting holes arranged horizontally on the side wall of the tunnel, and the third grouting holes arranged vertically below the tunnel. The number of first grouting holes is 4, and the four first grouting holes are symmetrically arranged on both sides of the tunnel, and the spacing between adjacent first grouting holes is 33.33°; the number of second grouting holes is 4, and the four second grouting holes are symmetrically arranged on both sides of the tunnel; the number of third grouting holes is 2, and the two third grouting holes are symmetrically arranged on both sides of the tunnel; The even-numbered rows of consolidation grouting holes include fourth grouting holes distributed radially along the arch, fifth grouting holes horizontally arranged on the side wall of the tunnel and sixth grouting holes arranged below the tunnel. The number of fourth grouting holes is 3, and the three fourth grouting holes are symmetrically arranged on both sides of the tunnel; the number of fifth grouting holes is 4, and the four fifth grouting holes are symmetrically arranged on both sides of the tunnel; the number of sixth grouting holes is 3, one of the sixth grouting holes is vertically arranged on the center line below the tunnel, and the other two sixth grouting holes are symmetrically inclined on both sides below the tunnel.

6. The method for blocking construction of a cross-dam traffic tunnel according to claim 3, characterized in that: In step S105, the backfill grouting is constructed by the buried pipe method, which specifically includes: placing the hole position, burying the grouting pipe and the grouting return pipe in the designated position on the top of the hole; checking the construction joints and concrete defects of the lining concrete, and processing the possible leakage parts; using the pure pressure grouting method for grouting construction, and sealing the hole after the grouting is completed.

7. The method for blocking construction of a dam-crossing traffic tunnel according to claim 1, characterized in that: Step S3, constructing a plugging body inside the tunnel, specifically includes: S301, Phase I plugging: backfill the entire tunnel with concrete; S302, Phase II plugging: A grouting corridor is set up downstream of the full-section concrete backfill section.

8. The method for blocking construction of a dam-crossing traffic tunnel according to claim 7, characterized in that: The first-stage plugging of step S301 is cast in two times using the step method, specifically including: the upstream side of the plugging section with a length of L is formed in one step with the whole section, pumped into the bin by a ground pump arranged at the hole entrance, and vibrated and compacted in layers by an inserted vibrator; then, a plugging section formwork is erected downstream of the plugging section, a concrete pump pipe is arranged in the middle of the plugging section along the arch, an exhaust pipe is arranged on the arch, concrete is pumped from low to high, and is vibrated and compacted in layers by an inserted vibrator; pumping can be stopped after slurry comes out of the exhaust pipe.

9. The method for blocking construction of a dam-crossing traffic tunnel according to claim 7, characterized in that: The second-stage plugging of step S302 is constructed by a three-layer pouring method, which specifically includes: The first layer is the bottom slab concrete pouring, the pouring height is 1m; The second layer is the corridor side wall, with a pouring height of 2m; The third layer is top supply, and the top supply concrete is delivered through the pump pipe outlet arranged at the top supply.

10. A blocking structure for a traffic tunnel across a dam, characterized in that: It includes a blind cover arranged at the upstream opening of the tunnel and a blocking body inside the tunnel, the blind cover includes a front cover and a door plug connected to the front cover, the front cover is arranged outside the opening, the front cover covers the opening and the area is larger than the opening area; the door plug is arranged in the hole at the opening.

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