Structure for improving water flow characteristic at junction of underground caverns

Abstract

The utility model provides a structure for improving the water flow characteristic at the junction of underground caverns, which comprises a vertical shaft spillway tunnel and a drainage tunnel, the spillway tunnel and the drainage tunnel intersect to form an intersection section of the spillway tunnel and the drainage tunnel, and the intersection section of the spillway tunnel and the drainage tunnel is communicated with the double-tunnel intersection and the drainage tunnel. A partition wall parallel to the axis of the spillway tunnel is arranged at the intersection section of the spillway tunnel and the drainage tunnel so as to separate the spillway tunnel from the intersection section of the spillway tunnel and the drainage tunnel, a bottom orifice is formed in the bottom of the partition wall, and a partition pier used for orifice diversion is arranged on the side, close to the drainage tunnel, of the partition wall. The included angle between the axis of the vertical shaft spillway tunnel and the axis of the drainage tunnel ranges from 15 degrees to 20 degrees, the drainage tunnel is reconstructed from a diversion tunnel, and a drainage steel pipe is lined in the diversion tunnel after diversion of the diversion tunnel is finished. The utility model can effectively solve the problem of surge caused by water flow hedging when the large flow of the flood discharge tunnel and the small flow of the drainage tunnel at the underground cavern junction converge, and improve the flow state of the tunnel junction, so that the water flow at the junction stably enters the downstream recession tunnel.

Description

Technical Field

[0001] The utility model relates to the field of water conservancy and hydropower engineering, in particular to a structure for improving water flow characteristics at the intersection of underground caverns, which integrates multiple tunnels for diversion, flood discharge, water delivery and emptying into one. Background Art

[0002] When designing traditional water conservancy and hydropower projects, diversion, flood discharge, water delivery and emptying are often designed as independent caverns or structures. Although this ensures the independence of each function, it also brings problems such as large engineering volume, high investment cost, large land area, and complex management and maintenance. With the development of science and technology, the advancement of engineering technology, and the improvement of environmental protection and resource conservation awareness, how to effectively integrate these functions into one or more underground caverns to achieve functional centralization and efficiency, save project investment, speed up the construction period, and at the same time reduce the impact on the environment and save resources has become an urgent problem to be solved in the field of water conservancy and hydropower engineering.

[0003] For this reason, the tunnels with different functions are often arranged separately during engineering design. After achieving their respective functions, the middle and rear sections of different tunnels are merged to share a tunnel and tail energy dissipation facilities. However, the flow pattern at the intersection of different tunnels is complex and chaotic, which is mainly reflected in: ① Uneven velocity distribution: Due to the change in the geometric shape of the tunnel intersection, the water velocity distribution may become uneven, resulting in excessive local velocity; ② Eddy and backflow: At the intersection of tunnels, the water flow may form eddy and backflow; ③ Change in water flow direction: When the water flows from one tunnel to another, the change in direction may cause the water flow to be turbulent and form an undesirable flow pattern; ④ Hydraulic jump: In some cases, the water flow may experience a hydraulic jump at the intersection, that is, the water flow transitions from the supercritical state to the subcritical state, the speed of the fluid suddenly slows down, part of the kinetic energy of the fluid is dissipated by the turbulence, and part of the kinetic energy is converted into potential energy, causing the liquid level to rise significantly. Long-term operation of poor flow patterns may cause water flow to scour and erode the tunnel structure, and even endanger the safe operation of the tunnel. Utility Model Content

[0004] The utility model aims to realize the multi-tunnel integrated arrangement of diversion, flood discharge, water delivery and emptying tunnels in water conservancy and hydropower projects through innovative design concepts and technical means, thereby improving the overall performance of the project, reducing investment costs, reducing the impact on the environment, and realizing resource conservation and efficient utilization. In view of the poor flow state at the intersection of underground tunnels, a structure for improving the water flow characteristics at the intersection of underground caverns is proposed, which can effectively solve the surge problem caused by the water flow collision at the intersection of underground caverns, improve the flow state at the intersection of tunnels, and make the water flow at the intersection section stably enter the downstream drainage tunnel.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A structure for improving water flow characteristics at the intersection of underground caverns comprises a vertical shaft flood discharge tunnel and a drainage tunnel. The flood discharge tunnel and the drainage tunnel intersect to form an intersection section of the flood discharge tunnel and the drainage tunnel. The intersection section of the flood discharge tunnel and the drainage tunnel is connected to a water retreat tunnel after the intersection of the two tunnels. A partition wall parallel to the axis of the flood discharge tunnel is arranged at the intersection section of the flood discharge tunnel and the drainage tunnel to separate the flood discharge tunnel from the intersection section of the flood discharge tunnel and the drainage tunnel. A bottom orifice is arranged at the bottom of the partition wall. A partition pier for orifice diversion is arranged on one side of the partition wall close to the drainage tunnel. The angle between the axis of the vertical shaft flood discharge tunnel and the axis of the drainage tunnel is between 15° and 20°. The drainage tunnel is converted from a diversion tunnel. After the diversion of the diversion tunnel is completed, a drainage steel pipe is lined in the diversion tunnel.

[0007] Furthermore, the vertical shaft flood discharge tunnel includes a vertical shaft flood discharge tunnel entrance, a vertical shaft section, an energy dissipation well, a vertical shaft flood discharge unpressured tunnel, an intersection section of the flood discharge tunnel and a water discharge tunnel, and a water retreat tunnel after the intersection of the two tunnels. The vertical shaft flood discharge tunnel entrance, the vertical shaft section, and the energy dissipation well are arranged in sequence from top to bottom. The vertical shaft flood discharge unpressured tunnel is horizontally connected to the vertical shaft section. The end section of the vertical shaft flood discharge unpressured tunnel intersects with the end section of the water discharge tunnel to form the intersection section of the flood discharge tunnel and the water discharge tunnel.

[0008] Furthermore, a drain pipe working piston valve is provided at the tail end of the drain pipe for conveying water and emptying the reservoir, and a drain hole water inlet and a drain pipe working valve well are respectively provided at both ends of the drain pipe, and the drain pipe working piston valve is located in the drain pipe working valve well.

[0009] Furthermore, the width of the top of the partition wall is 0.5m to 1m, the slope of the bottom of the partition wall is consistent with the slope of the bottom of the spillway tunnel, the top is horizontal, and the elevation of the top of the partition wall is not lower than the sum of the water level at the maximum discharge flow of the vertical shaft spillway tunnel and the safety superelevation.

[0010] Furthermore, three bottom openings are arranged at the bottom of the partition wall, the center line of the first opening is located at 0.36 times the length of the partition wall, the size of each opening is 2×0.75m, and the edges of the openings are 1.5m apart; four partition piers are arranged upstream on one side of the drainage hole of the bottom opening, and the thickness of the partition piers from the left side to the right side of the drainage hole are 1.66m, 0.45m, 0.45m and 0.64m.

[0011] Furthermore, after the two tunnels intersect, the water retreat tunnel is an open flow tunnel, and the tunnel is in the shape of a city gate tunnel.

[0012] Furthermore, the drainage tunnel is connected to a 1:4 slope section and then intersects with the vertical shaft flood discharge tunnel.

[0013] The beneficial effects of the utility model are:

[0014] 1. The four-tunnel engineering layout scheme of diversion, flood discharge, water delivery and emptying tunnels was realized, which achieved the centralization and efficiency of functions, saved project investment, accelerated the construction period, reduced the impact on the environment and saved resources;

[0015] 2. The partition wall set at the intersection of the two tunnels blocks the water flow in the discharge tunnel from directly impacting the flow state in the flood discharge tunnel, avoiding the impact of high surge waves on the cave top after the two water flows collide at the intersection; the partition wall raises the water level at the end of the discharge tunnel before the intersection, forming a submerged water jump at the end of the discharge tunnel, with good energy dissipation effect;

[0016] 3. After the hole is opened at the bottom of the partition wall, part of the water flow on the drainage hole side passes through the hole and merges with the water flow in the flood discharge hole. The remaining water overflows from the top of the partition wall into the flood discharge hole. Since the hole shares part of the flow, the overflow water volume on the top of the wall is reduced, and the overflow uniformity on the top of the wall is better.

[0017] 4. The outflow from the bottom of the partition wall overflows from the top to form an energy dissipation water cushion. The downstream flow pattern quickly adjusts and stabilizes before entering the downstream drainage tunnel. The maximum water surface height along the intersection section is relatively low. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a plan layout diagram of a vertical shaft flood discharge tunnel and a water discharge tunnel according to an embodiment of the utility model;

[0019] Figure 2 It is a longitudinal section layout diagram of a vertical shaft flood discharge tunnel according to an embodiment of the utility model;

[0020] Figure 3 A longitudinal section view of a drain hole according to an embodiment of the utility model;

[0021] Figure 4 It is a schematic diagram of a structure for improving the water flow characteristics at the intersection of underground caverns according to an embodiment of the utility model;

[0022] Figure 5 for Figure 4 Structural layout of the middle partition wall;

[0023] Figure 6 for Figure 4 Middle AA section;

[0024] Figure 7 This is the distribution map of the highest water surface line along the partition wall;

[0025] The reference numerals in the figures are described as follows:

[0026] 1-inlet of vertical shaft flood discharge tunnel; 2-vertical shaft section of vertical shaft flood discharge tunnel; 3-energy dissipation well of vertical shaft flood discharge tunnel; 4-pressure-free tunnel of vertical shaft flood discharge; 5-water inlet of drainage tunnel; 6-drainage steel pipe; 7-drainage pipe working piston valve; 8-drainage pipe working valve well; 9-drainage tunnel; 10-intersection section of flood discharge tunnel and drainage tunnel; 11-water retreat tunnel after the intersection of the two tunnels; 12-partition wall; 13-bottom opening; 14-partition pier; 15-overflow water surface line of drainage tunnel on the top of partition wall. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] See also Figure 1 to Figure 7 The embodiment of the utility model provides a structure for improving the water flow characteristics at the intersection of underground caverns, including a vertical shaft flood discharge tunnel, a drainage tunnel 9 (taking into account the emptying function), an intersection section 10 of the flood discharge tunnel and the drainage tunnel, a water retreat tunnel 11 after the intersection of the two tunnels, and a partition wall 12, wherein the partition wall 12 is used to separate the vertical shaft flood discharge tunnel and the drainage tunnel 9, a bottom orifice 13 is provided at the bottom of the partition wall 12, and a partition pier 14 for orifice diversion is provided on the side of the partition wall 12 close to the drainage tunnel 9.

[0029] The vertical shaft flood spillway is a channel connecting the water flow in the upstream reservoir area and the river channel downstream of the dam. During the flood season, flood water enters the downstream river channel through this channel to discharge excess flood water. The vertical shaft flood spillway includes a vertical shaft flood spillway inlet 1 (with a circular overflow weir), a vertical shaft section 2, an energy dissipation well 3, a vertical shaft flood spillway pressure-free tunnel 4, a flood spillway and water discharge tunnel intersection section 10, and a double-hole intersection backwater tunnel 11. The vertical shaft flood spillway inlet 1, the vertical shaft section 2, and the energy dissipation well 3 are arranged in sequence from top to bottom. The vertical shaft flood spillway pressure-free tunnel 4 is horizontally connected to the vertical shaft section 2. The end section of the vertical shaft flood spillway pressure-free tunnel 4 intersects with the end section of the water discharge tunnel 9 to form the flood spillway and water discharge tunnel intersection section 10. The flood spillway and water discharge tunnel intersection section 10 is connected to the double-hole intersection backwater tunnel 11. The double-hole intersection backwater tunnel 11 is an open flow tunnel, and the tunnel is in the shape of a city gate tunnel.

[0030] The drainage hole 9 is used to realize the water delivery and emptying functions of the reservoir area. In normal operation, the drainage hole discharges water to realize the water delivery function; in the case of maintenance or other emergency situations in the reservoir area, it plays the role of emptying the reservoir; the drainage hole is rebuilt from the diversion hole. After the diversion of the diversion hole is completed, the drainage steel pipe 6 and the drainage pipe working piston valve 7 are lined in the diversion hole for water delivery and emptying the reservoir, and the drainage hole water inlet 5 and the drainage pipe working valve well 8 (such as Figure 3 The drain steel pipe 6 is connected to the drain hole 9 after the drain working piston valve 7, and the drain working piston valve 7 is located in the drain working valve well 8. The drain hole 9 is connected to a 1:4 slope section, and then intersects with the flood discharge tunnel, and then enters the downstream double-hole intersection backwater tunnel 11.

[0031] The vertical shaft flood discharge tunnel and the drainage tunnel 9 are arranged separately, and the axis of the flood discharge tunnel and the drainage tunnel are directly intersected within 20 degrees, for example, between 15 degrees and 20 degrees (17.5 degrees in this embodiment), and after the intersection, they share a water withdrawal tunnel, realizing the engineering layout scheme of integrating diversion, flood discharge, water delivery and drainage tunnels. The specific implementation steps are as follows:

[0032] ① During the diversion period of the project construction, only the drainage tunnel 9 (without the drainage steel pipe 6) and the retreat tunnel 11 after the intersection of the two tunnels are built. The water flows through the drainage tunnel 9 → the intersection section 10 of the flood discharge tunnel and the drainage tunnel → the retreat tunnel 11 after the intersection of the two tunnels into the downstream river channel, thus realizing the diversion effect of the project;

[0033] ② After the diversion is completed, the drainage steel pipe 6 and the drainage pipe working piston valve 7 are lined in the drainage hole 9, and the water flows through 5→6→7→9→10→11 to realize the water delivery and draining functions of the project, among which the drainage pipe working piston valve 7 can adjust the water delivery and draining flow;

[0034] ③ After the diversion is completed, the flood discharge tunnel and the water discharge tunnel intersection section 10 are connected, and the water flows through 1→2→3→4→10→11 into the downstream river channel, realizing the flood discharge function of the project;

[0035] The intersection section 10 of the flood discharge tunnel and the water discharge tunnel is provided with a partition wall 12 (such as Figure 4 As shown), the flood discharge tunnel is separated from the flood discharge tunnel and the water discharge tunnel intersection section 10. The partition wall 12 is a gravity retaining wall, which adopts a reinforced concrete structure.

[0036] The width of the top of the partition wall 12 is 0.5m to 1m (0.5m is taken in this embodiment), the bottom slope of the partition wall 12 is consistent with the bottom slope of the spillway tunnel, the top is horizontal, and the elevation of the top of the partition wall is not lower than the sum of the water level and the safety superelevation at the maximum discharge flow of the vertical shaft spillway tunnel. A partition pier 14 is set on the right side of the partition wall 12 close to the drainage tunnel, and three bottom orifices 13 are set at the bottom. From upstream to downstream, the center line of the first orifice 13 is located at 0.36 times the length of the partition wall 12, and the size of each orifice is 2×0.75m, and the orifice edges are 1.5m apart. Four partition piers 14 are set upstream of the drainage tunnel side of the bottom orifice 13. From the left side to the right side of the drainage tunnel, the thickness of the partition piers is 1.66m, 0.45m, 0.45m and 0.64m, and the partition pier 14 is used for orifice diversion.

[0037] When the spillway tunnel is operated alone, the discharge pipe working piston valve 7 in front of the discharge tunnel 9 is closed, and the discharge tunnel does not flow. The partition wall 12 provided in this embodiment separates the spillway tunnel and the discharge tunnel, and the water flow in the spillway tunnel will not diffuse to the discharge tunnel 9 at the intersection section, and the flow pattern will not be affected by the discharge tunnel 9; and when the spillway tunnel 9 is operated at the maximum flow rate, the height of the partition wall 12 is higher than the water surface line of the spillway tunnel, and the water flow will not overflow and diffuse to one side of the discharge tunnel 9. Therefore, when the spillway tunnel is operated alone, the flow pattern is not affected by the intersection section.

[0038] When the drainage tunnel is operated alone, the outflow of the drainage steel pipe 6 falls after passing through the 1:4 slope section, and the tail partition wall 12 raises the water level at the end of the drainage tunnel, forming a submerged water jump at the outlet of the drainage tunnel 9, and fully dissipating energy before the intersection section. After energy dissipation, part of the water flows through the bottom orifice 13 of the partition wall 12 and enters the flood discharge tunnel, and the remaining part of the water flows overflow from the top of the partition wall 12 and falls into the flood discharge tunnel. The partition wall 12 blocks the water flow in the drainage tunnel from directly impacting the left side wall of the flood discharge tunnel to avoid causing higher surges; the bottom orifice 13 set at the bottom of the partition wall 12 shares part of the flow of the drainage tunnel to avoid the generation of higher surges when the top of the partition wall 12 overflows. In addition, the outflow of the bottom orifice 13 of the partition wall 12 is an energy dissipation water cushion formed by the top overflow, and the downstream flow state quickly adjusts and stabilizes and enters the downstream retreat tunnel 11.

[0039] When the vertical shaft spillway tunnel and the drainage tunnel are in operation at the same time, at the intersection 10 of the spillway tunnel and the drainage tunnel, after the water flow on the drainage tunnel 9 side reaches the intersection partition wall 12, a part of the water flows through the bottom opening 13 of the partition wall 12 and merges with the bottom layer of the water flow on the side of the vertical shaft spillway tunnel, and the remaining water flows down from the top of the partition wall and merges with the surface layer of the water flow on the side of the vertical shaft spillway tunnel. The maximum water surface height of the intersection section is relatively low ( Figure 7 A submerged water jump is formed at the end of the drainage tunnel 9, and the head of the jump is located upstream of the end of the 1:4 slope section. From the end of the 1:4 slope section to the partition wall, the water level gradually rises, the water jump is complete, and the overflow uniformity on the top of the wall is good.

[0040] The utility model improves the structure of water flow characteristics at the intersection of underground caverns. The vertical shaft flood discharge tunnel and the water discharge tunnel are arranged separately at the head only, and then share a water withdrawal tunnel, realizing the engineering layout scheme of four tunnels in one, namely, diversion, flood discharge, water delivery and emptying tunnel. The partition wall 12 arranged at the intersection of the two tunnels blocks the water flow in the water discharge tunnel from directly impacting the flow state in the flood discharge tunnel, avoiding the formation of high surge waves impacting the cave top after the two water flows in the intersection section collide; the partition wall 12 blocks the end of the water discharge tunnel in front of the intersection section. The water level forms a submerged water jump at the end of the drainage tunnel, and the energy dissipation effect is good; after the hole is opened at the bottom of the partition wall, part of the water flow on the drainage tunnel side passes through the orifice and merges with the water flow in the flood discharge tunnel, and the remaining water flow overflows from the top of the partition wall into the flood discharge tunnel. Since the orifice shares part of the flow, the overflow water volume on the top of the wall is reduced, and the overflow uniformity on the top of the wall is better; the outflow at the bottom of the partition wall is the top overflow to form an energy dissipation water cushion, and the downstream flow state is quickly adjusted and stabilized before entering the downstream drainage tunnel. The maximum water surface height along the intersection section is relatively low. The utility model can effectively solve the problem of surge waves caused by the water flow collision at the intersection of underground caverns, improve the flow state at the intersection of tunnels, and make the water flow in the intersection section stably enter the downstream drainage tunnel.

[0041] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by technicians in this technical field within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A structure for improving water flow characteristics at the intersection of underground caverns, characterized in that: It includes a vertical shaft flood discharge tunnel and a drainage tunnel. The flood discharge tunnel and the drainage tunnel intersect to form an intersection section of the flood discharge tunnel and the drainage tunnel. The intersection section of the flood discharge tunnel and the drainage tunnel is connected to the retreat tunnel after the intersection of the two tunnels. The intersection section of the flood discharge tunnel and the drainage tunnel is provided with a partition wall parallel to the axis of the flood discharge tunnel to separate the flood discharge tunnel from the intersection section of the flood discharge tunnel and the drainage tunnel. A bottom orifice is provided at the bottom of the partition wall, and a partition pier for orifice diversion is provided on the side of the partition wall close to the drainage tunnel; the angle between the axis of the vertical shaft flood discharge tunnel and the axis of the drainage tunnel is between 15° and 20°. The drainage tunnel is converted from a diversion tunnel. After the diversion of the diversion tunnel is completed, a drainage steel pipe is lined in the diversion tunnel.

2. The structure for improving water flow characteristics at the junction of underground caverns according to claim 1 is characterized in that: The vertical shaft flood discharge tunnel includes a vertical shaft flood discharge tunnel entrance, a vertical shaft section, an energy dissipation well, a vertical shaft flood discharge unpressured tunnel, an intersection section of the flood discharge tunnel and a water discharge tunnel, and a water retreat tunnel after the intersection of the two tunnels. The vertical shaft flood discharge tunnel entrance, the vertical shaft section, and the energy dissipation well are arranged in sequence from top to bottom. The vertical shaft flood discharge unpressured tunnel is horizontally connected to the vertical shaft section. The end section of the vertical shaft flood discharge unpressured tunnel intersects with the end section of the water discharge tunnel to form the intersection section of the flood discharge tunnel and the water discharge tunnel.

3. The structure for improving water flow characteristics at the junction of underground caverns according to claim 1 is characterized in that: A drain pipe working piston valve is arranged at the tail end of the drain pipe for conveying water and emptying the reservoir, and a drain hole water inlet and a drain pipe working valve well are arranged at both ends of the drain pipe respectively, and the drain pipe working piston valve is located in the drain pipe working valve well.

4. The structure for improving water flow characteristics at the junction of underground caverns according to claim 1 is characterized in that: The width of the top of the partition wall is 0.5m to 1m, the slope of the bottom of the partition wall is consistent with the slope of the bottom of the spillway tunnel, the top is horizontal, and the elevation of the top of the partition wall is not lower than the sum of the water level at the maximum downstream flow of the vertical shaft spillway tunnel and the safety superheight.

5. The structure for improving water flow characteristics at the junction of underground caverns according to claim 1, characterized in that: Three bottom openings are arranged at the bottom of the partition wall, the center line of the first opening is located at 0.36 times the length of the partition wall, the size of each opening is 2×0.75m, and the edges of the openings are 1.5m apart; four partition piers are arranged upstream on one side of the drainage hole of the bottom opening, from the left side to the right side of the drainage hole, and the thickness of the partition piers are 1.66m, 0.45m, 0.45m and 0.64m.

6. The structure for improving water flow characteristics at the junction of underground caverns according to claim 1, characterized in that: The water-relief tunnel after the intersection of the two tunnels is an open flow tunnel, and the tunnel is in the shape of a city gate tunnel.

7. The structure for improving water flow characteristics at the junction of underground caverns according to claim 1, characterized in that: The drainage tunnel is followed by a 1:4 slope section and then intersects with the vertical shaft flood discharge tunnel.

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