Gas explosion prevention staging implementation structure of diversion tunnel plugging body

Abstract

The utility model discloses a staging implementation structure for preventing gas explosion of a diversion tunnel plugging body. The staging implementation structure comprises a diversion tunnel formed through a lining layer, and first-stage plugging concrete, second-stage plugging concrete, an upstream cofferdam, a downstream cofferdam, an exhaust pipe and a drainage pipe which are arranged in the diversion tunnel. Compared with other projects which solve the problem of gas explosion in front of the plug by drilling holes above the top of the hole, the structure has the most advantages of low cost, no need of drilling holes and construction period saving. If the construction period progress is tense and water seepage is slow behind the gate and before the plug, water can be filled from the tail of the drainage pipe to accelerate gas discharge in front of the plug, so that the construction period is facilitated. Exhaust hole inlets of the exhaust pipes are formed in the top, and exhaust is facilitated. The exhaust butterfly valve, the exhaust pipe tail and the drainage butterfly valve and the drainage pipe tail are arranged near the diversion tunnel bottom plate, opening and closing are convenient, and grouting construction is more convenient.

Description

Technical Field

[0001] This utility model belongs to the field of hydropower and water conservancy engineering technology, and in particular relates to a phased implementation structure for preventing gas explosion of a diversion tunnel sealing body. Background Technology

[0002] In order to expedite the construction period and create conditions for early water storage and power generation or benefit, the diversion tunnel in hydropower and water conservancy projects is often sealed in two phases, that is, the plug is poured in stages. The first-stage plug cannot be too long, otherwise it will prolong the construction period. Therefore, the first-stage plug is weak compared to the design length after the entire project is completed. High water head will also bring about gas explosion problems. The gas explosion risk is serious and may endanger the safety of the first-stage plug, affecting the safety and progress of the project.

[0003] Given the risk of gas explosion and its safety when the first-phase plug fails to reach its designed length, it is essential to design a structure and construction method that can resolve gas explosions, ensure the safety of the first-phase plug, create conditions for early water storage and benefit, and facilitate sealing and grouting. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a phased implementation structure for preventing gas explosion of the diversion tunnel sealing body.

[0005] This utility model is achieved through the following technical solution.

[0006] This utility model provides a phased implementation structure for preventing gas explosions by sealing a diversion tunnel, including a diversion tunnel formed by a lining layer and a first-stage sealing concrete, a second-stage sealing concrete, an upstream cofferdam, a downstream cofferdam, an exhaust pipe, and a drainage pipe installed inside the diversion tunnel. The upstream cofferdam is located on one side of the first-stage sealing concrete, and the second-stage sealing concrete is located on the other side of the first-stage sealing concrete. The first-stage sealing concrete and the second-stage sealing concrete are connected. The downstream cofferdam is located on the other side of the second-stage sealing concrete. The exhaust pipe and the drainage pipe are installed through the first-stage sealing concrete and the second-stage sealing concrete.

[0007] Preferably, one end of the exhaust pipe passes through the downstream cofferdam. The exhaust pipe includes a vertical section and a horizontal section. The vertical section of the exhaust pipe extends to the top of the diversion tunnel, and the horizontal section of the exhaust pipe passes through the second-phase sealing concrete and the downstream cofferdam.

[0008] Preferably, the drainage pipe extends through the upstream and downstream cofferdams at both ends, and is installed at the bottom of the diversion tunnel and along the centerline of the diversion tunnel.

[0009] Preferably, an exhaust pipe valve is provided on the exhaust pipe, and a drain pipe valve is provided on the drain pipe.

[0010] Preferably, the exhaust pipe valve and the drain pipe valve are connected to the guide hole via valve supports.

[0011] Preferably, a reserved grouting gallery is provided within the secondary sealing concrete, and an operating well is provided at one end of the reserved grouting gallery. A ladder composed of embedded ladder components is provided inside the operating well.

[0012] Preferably, the operating well is located within the large-diameter area of ​​the diversion tunnel.

[0013] Preferably, waterstop strips are provided on the first-stage sealing concrete and the second-stage sealing concrete respectively.

[0014] The beneficial effects of this utility model are as follows:

[0015] Compared to other engineering methods that solve the gas explosion problem before the plug by drilling holes above the tunnel top, this structure has the advantages of low cost, no drilling required, and reduced construction time. If the construction schedule is tight and water seepage before the plug is slow after the gate, water can be injected from the tail of the drain pipe to accelerate the removal of gas before the plug, which is beneficial for expediting the construction period. The vent inlet of the vent pipe is located at the top, which is conducive to venting. The vent butterfly valve and the tail of the vent pipe, as well as the drain butterfly valve and the tail of the drain pipe, are all located near the bottom plate of the diversion tunnel, making opening and closing convenient and grouting construction more convenient. Attached Figure Description

[0016] Figure 1 This is a schematic cross-sectional view of the structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the structure of this utility model;

[0018] Figure 3 This is a schematic diagram of the operating well of this utility model;

[0019] Figure 4 This is a schematic diagram of the AA cross-section of the operating well of this utility model;

[0020] In the diagram: 1-Excavation line, 2-Lined layer, 3-Center line of diversion tunnel, 4-First-stage sealing concrete, 5-Second-stage sealing concrete, 6-Grouting gallery, 61-Operating well, 7-Upstream cofferdam, 8-Downstream cofferdam, 9-Exhaust pipe, 10-Drainage pipe, 11-Valve support, 12-Drainage pipe valve, 13-Exhaust pipe valve, 14-Waterstop strip, 15-Ladder, 16-Ladder embedded part. Detailed Implementation

[0021] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.

[0022] Example:

[0023] like Figures 1 to 4As shown, a phased implementation structure for preventing gas explosion of a diversion tunnel sealing body includes a diversion tunnel formed by a lining layer 2 and a first-stage sealing concrete 4, a second-stage sealing concrete 5, an upstream cofferdam 7, a downstream cofferdam 8, an exhaust pipe 9, and a drainage pipe 10 installed inside the diversion tunnel. The upstream cofferdam 7 is located on one side of the first-stage sealing concrete 4, and the second-stage sealing concrete 5 is located on the other side of the first-stage sealing concrete 4. The first-stage sealing concrete 4 and the second-stage sealing concrete 5 are connected. The downstream cofferdam 8 is located on the other side of the second-stage sealing concrete 5. The exhaust pipe 9 and the drainage pipe 10 are installed through the first-stage sealing concrete 4 and the second-stage sealing concrete 5.

[0024] The concrete lining layer 2 is set along the excavation line 1 formed by smooth blasting of the surrounding rock. The concrete lining layer 2 is a support form to ensure the safety and stability of the tunnel, and also has the function of reducing the roughness of the flow through the diversion tunnel.

[0025] The first phase of the sealing concrete 4 serves as a temporary water barrier during the water storage period.

[0026] After the second-stage sealing concrete 5 is poured to the designed length, the water-blocking safety reserve is higher; the first-stage sealing concrete 4 and the second-stage sealing concrete 5 form a plug.

[0027] Upstream cofferdam 7 is a temporary cofferdam formed using clay bags, which can block upstream water or seepage water from behind the gate and in front of the plug during the construction period, creating dry conditions for the plug construction.

[0028] Downstream cofferdam 8 is a temporary cofferdam formed using clay and straw bags, creating conditions for dry-land construction at the head of the project.

[0029] The exhaust pipe 9 is a steel pipe, which is located near the top arch upstream. After the water level rises, the air near the top arch can be compressed and discharged through the exhaust pipe 9 to the plug, so as not to cause an air explosion.

[0030] Drainage pipe 10 is a temporary installation. Its function is to drain water or seepage from upstream and prevent excessive water accumulation from overflowing the upstream cofferdam 7 and affecting the construction of the dry land plug.

[0031] The exhaust pipe 9 is installed through the downstream cofferdam 8 at one end. The exhaust pipe 9 includes a vertical section (vertical shaft section) and a horizontal section (including an upper horizontal section and a lower horizontal section, the upper horizontal section is connected to the high point of the vertical shaft section, and the lower horizontal section is connected to the low point of the vertical shaft section). The vertical section of the exhaust pipe 9 extends to the top of the diversion tunnel. The horizontal section of the exhaust pipe 9 penetrates the second-stage sealing concrete 5 and the downstream cofferdam 8. The exhaust pipe 9 is mostly installed in the first-stage sealing concrete 4 as a horizontal section.

[0032] The drainage pipe 10 passes through the upstream cofferdam 7 and the downstream cofferdam 8 at both ends, and is set at the bottom of the diversion tunnel and along the center line 3 of the diversion tunnel.

[0033] An exhaust pipe valve 13 is provided on the exhaust pipe 9, and a drain pipe valve 12 is provided on the drain pipe 10. Both the exhaust pipe valve 13 and the drain pipe valve 12 are butterfly valves. Both the exhaust pipe valve 13 and the drain pipe valve 12 are located at the bottom of the operating well 61, so that personnel can easily enter the operating well 61 to operate them.

[0034] The exhaust pipe valve 13 and the drain pipe valve 12 are respectively connected to the guide hole through the valve support 11.

[0035] A reserved grouting gallery 6 is provided within the secondary sealing concrete 5. An operating well 61 is located at one end of the reserved grouting gallery 6. A ladder 15, composed of embedded ladder components 16, is installed within the operating well 61. The ladder 15, positioned within the operating well 61, allows passage down to the exhaust pipe valve 13 and the drainage pipe valve 12 after the secondary sealing concrete 5 has completed its consolidation grouting, enabling the closure of both valves. The ladder embedded components 16 are formed by bending steel bars and embedding them into the concrete.

[0036] The operating well 61 is located within the large-diameter area of ​​the diversion tunnel. The large-diameter area is located in the middle of the diversion tunnel, and the diameters at both ends of the large-diameter area are smaller than those of the large-diameter area.

[0037] Waterstop strips 14 are respectively installed on the first-stage sealing concrete 4 and the second-stage sealing concrete 5. The waterstop strips 14 are arranged circumferentially at the end of the first-stage sealing concrete 4 away from the second-stage sealing concrete 5 and the end of the second-stage sealing concrete 5 away from the first-stage sealing concrete 4, which can extend the seepage path.

[0038] A construction method for a phased implementation structure for preventing gas explosions in a diversion tunnel sealing body includes the following steps:

[0039] Step 1: Construct the upstream cofferdam 7. Construct it to the water-blocking elevation during the construction period according to the design flow rate, taking into account the safety freeboard and wave run-up. During the construction of the cofferdam, pre-embed drainage pipes 10 at a suitable elevation, which needs to be determined in conjunction with the actual project.

[0040] Step 2: Construct the downstream cofferdam 8, and after filling to a suitable elevation, pre-embed the lower section of the drainage pipe 10 and the vent pipe 9 so that the upstream and downstream cofferdams are connected by the drainage pipe 10, and the upstream water during the plugging construction is drained to the downstream of the plug; the distance between the upstream and downstream cofferdams should be considered to ensure the space for the installation of construction equipment while ensuring the first and second phases of the plugging construction.

[0041] Step 3: Install drainage pipe valve 12 and exhaust pipe valve 13. These two butterfly valves are in the open state, which provides the flow guidance capacity for upstream and downstream cofferdams to block water and drainage pipes to discharge water. This ensures that the first-stage sealing concrete 4 and the subsequent second-stage sealing concrete 5 can be constructed on dry ground in the foundation pit between the two cofferdams.

[0042] Step 4: Erect the formwork required for pouring the first-stage sealing concrete 4, install the circumferential waterstop strip 14, pre-embed the horizontal backfill grouting pipe, and set up the upper horizontal section and vertical shaft section of the exhaust pipe 9 inside the formwork. Connect the upper horizontal section, vertical shaft section and lower horizontal section of the exhaust pipe 9. Only after completing the above work can the first-stage sealing concrete 4 be poured. After the first-stage sealing concrete 4 is formed, the drainage pipe 10 and the exhaust pipe 9 have drainage and exhaust functions. The water coming in during the plugging construction period and the gas caused by the water filling in front of the plug after the gate can be discharged to the rear of the downstream cofferdam 8.

[0043] Step 5: Unlike the traditional circumferential backfill grouting for the gap between the lining concrete and the surrounding rock, after the first phase of sealing concrete 4 is poured, horizontal circumferential backfill grouting can be carried out through the pre-embedded horizontal backfill grouting pipe. There is no need to wait until the concrete reaches 70% of the design strength, so it can gain an advantage in terms of progress.

[0044] Step Six: After the first phase of sealing concrete 4 is completed with horizontal backfill grouting, the predetermined preliminary water blocking task can be completed. There are two situations in which gas explosion may occur: sometimes when the gate is closed, the seepage of water behind the gate and in front of the plug will cause gas explosion; sometimes when the gate is open, the rapid filling of water and compression of air in the tunnel will cause gas explosion. The exhaust structure proposed in this utility model can solve the gas explosion problem in the above situations.

[0045] Step 7: Erect the formwork for pouring the second-stage sealing concrete 5, install the ladder embedded part 16, pre-embed PVC grouting hole indicator for consolidation grouting hole position, and reserve the grouting gallery 6. After the construction of the second-stage sealing concrete 5, the steel ladder 15 will be formed in the grouting gallery 6.

[0046] Step 8: Since the second-phase sealing concrete 5 has a pre-reserved consolidation grouting gallery 6 and is not completely compacted, it is different from the first-phase sealing concrete 4. After the second-phase sealing concrete 5 is constructed, it needs to reach 70% of the design strength before horizontal circumferential backfilling grouting can be carried out through the circumferential waterstop strip 14. Seven days after the backfilling grouting is completed, the pre-embedded PVC holes can be swept from the grouting gallery 6 and drilled to the design depth of consolidation grouting to carry out consolidation grouting in order to improve the integrity and seepage prevention performance of the surrounding rock.

[0047] Step 9: After the consolidation grouting is completed, when water is found to start to come out of the vent pipe 9, it indicates that the venting before the plug is completed. At this time, you can go down to the butterfly valve from the operating well 16 and close the drain pipe 10 and the vent pipe 9 through the drain pipe valve 12 and the vent pipe valve 13.

[0048] Step 10: Seal the grouting gallery 6. After the grouting gallery 6 is sealed, the inside of the plug is not dense. The holes in the drainage pipe 9 and the vent pipe 10 weaken the integrity of the plug. At this time, grouting can be carried out on the holes in the second-stage sealing concrete section 5 from the tail of the vent pipe 9 and the drainage pipe 10. The holes in the first-stage sealing concrete section 4 do not need to be grouted.

Claims

1. A phased implementation structure for preventing gas explosion of a diversion tunnel sealing body, characterized in that: It includes a diversion tunnel formed by the lining layer (2) and a first-stage sealing concrete (4), a second-stage sealing concrete (5), an upstream cofferdam (7), a downstream cofferdam (8), an exhaust pipe (9), and a drainage pipe (10) installed inside the diversion tunnel. The upstream cofferdam (7) is located on one side of the first-stage sealing concrete (4), and the second-stage sealing concrete (5) is located on the other side of the first-stage sealing concrete (4). The first-stage sealing concrete (4) and the second-stage sealing concrete (5) are connected. The downstream cofferdam (8) is located on the other side of the second-stage sealing concrete (5). The exhaust pipe (9) and the drainage pipe (10) are installed through the first-stage sealing concrete (4) and the second-stage sealing concrete (5).

2. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 1, characterized in that: The exhaust pipe (9) is installed through the downstream cofferdam (8) at one end. The exhaust pipe (9) includes a vertical section and a horizontal section. The vertical section of the exhaust pipe (9) extends to the top of the diversion tunnel, and the horizontal section of the exhaust pipe (9) passes through the second-phase sealing concrete (5) and the downstream cofferdam (8).

3. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 1, characterized in that: The drainage pipe (10) passes through the upstream cofferdam (7) and the downstream cofferdam (8) at both ends. The drainage pipe (10) is set at the bottom of the diversion tunnel and along the center line (3) of the diversion tunnel.

4. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 1, characterized in that: An exhaust pipe valve (13) is provided on the exhaust pipe (9), and a drain pipe valve (12) is provided on the drain pipe (10).

5. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 4, characterized in that: The exhaust pipe valve (13) and the drain pipe valve (12) are respectively connected to the diversion hole through the valve support (11).

6. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 1, characterized in that: A reserved grouting gallery (6) is provided in the second-stage sealing concrete (5). An operating well (61) is provided at one end of the reserved grouting gallery (6). A ladder (15) composed of ladder embedded parts (16) is provided in the operating well (61).

7. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 6, characterized in that: The operating well (61) is located in the large-diameter area of ​​the diversion tunnel.

8. The phased implementation structure for preventing gas explosion of a diversion tunnel sealing body as described in claim 1, characterized in that: Waterstop strips (14) are respectively installed on the first-stage sealing concrete (4) and the second-stage sealing concrete (5).

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