Pressure-to-non-pressure diversion tunnel

Abstract

The utility model discloses a pressure-to-non-pressure diversion tunnel which comprises a pressure section and a non-pressure section, the pressure section is communicated with an upstream water source, the non-pressure section is communicated with a downstream water using area, the pressure section and the non-pressure section are smoothly connected through a transition section, the diameter of the upstream end of the transition section is equal to that of the pressure section, and the diameter of the non-pressure section is equal to that of the upstream end of the transition section. The diameter of the downstream end of the transition section is equal to that of the non-pressure section, the diameter of the pressure section is smaller than that of the non-pressure section, and the diameter of the transition section is gradually increased in the water flow direction. Geometric characteristics of the transition section are reasonably designed, the transition section is tangentially connected with the pressure section and the non-pressure section, water flow is transitionally and smoothly connected from the pressure section to the transition section to the non-pressure section, and the disorder phenomenon of the water flow is avoided; the diameter of the transition section is gradually increased in the water flow direction, so that the water flow speed is slowed down, water flows smoothly, the water level is lowered, water pressure borne by the top of the tunnel is reduced, and the service life of the tunnel is prolonged.

Description

Technical Field

[0001] The utility model relates to the field of water conservancy and hydropower engineering, in particular to a pressure-to-no-pressure water diversion tunnel. Background Art

[0002] A diversion tunnel is a water transmission structure that diverts power generation water from the upstream reservoir to the power plant. Based on hydraulic conditions, it can be divided into unpressurized and pressurized tunnels. Unpressurized tunnels often have a gate-shaped cross-section, with open flow, while pressurized tunnels often have a horseshoe or circular cross-section, with full, pressurized flow.

[0003] Currently, the overall layout of a hydropower station consists of an upstream water intake structure, a diversion pressure tunnel, a surge chamber (surge well), penstocks, a powerhouse, and a downstream river channel. When water flows through the diversion pressure tunnel, the tunnel is filled with water, and the tunnel roof is subject to a certain amount of water pressure. A pressurized tunnel has no free surface, and the water flow pattern is more favorable. However, the high water pressure inside the tunnel requires strong rock to withstand the water pressure, otherwise it is uneconomical. Pressurized tunnels are suitable for conditions with good geological conditions. However, due to the complex environmental conditions and operating mechanisms of hydraulic high-pressure diversion tunnels, many unresolved issues remain regarding the spacing and width of cracks in the tunnel lining, the infiltration of high-pressure water and water loads, and calculation and analysis methods. If the traditional diversion pressure tunnel water supply method can be changed to a non-pressure open channel water supply method, it will avoid the problems of long pressure tunnels, difficult excavation, or the inability to excavate pressure tunnels due to complex geology. Utility Model Content

[0004] In order to solve the above problems, the utility model proposes a pressurized to non-pressurized water diversion tunnel, which includes a pressurized section and a non-pressurized section. The pressurized section is connected to the upstream water source, and the non-pressurized section is connected to the downstream water use area. The pressurized section and the non-pressurized section are smoothly connected by a gradient section. The diameter of the upstream end of the gradient section is equal to the diameter of the pressurized section, and the diameter of the downstream end of the gradient section is equal to the diameter of the non-pressurized section. The diameter of the pressurized section is smaller than the diameter of the non-pressurized section, and the diameter of the gradient section gradually increases along the direction of water flow.

[0005] Furthermore, a longitudinal section of the gradual change section along the water flow direction forms a cave top contour line and a cave bottom contour line, and a vertical distance between the cave top contour line and the cave bottom contour line gradually increases along the water flow direction.

[0006] Furthermore, the cave roof contour line conforms to the piecewise function The shape of the formula, where d1 is the diameter of the pressure section, d2 is the diameter of the non-pressure section, L is the length of the gradient section, and a and b satisfy The cave top contour line of the gradual section is tangently connected to the pressure section and the non-pressure section.

[0007] Furthermore, the cave bottom contour line is a horizontal straight line segment with a length of L.

[0008] Furthermore, the cave roof contour line conforms to the piecewise function The shape of the formula, where d1 is the diameter of the pressure section, d2 is the diameter of the non-pressure section, and L is the length of the gradient section.

[0009] The beneficial effects of the utility model are as follows:

[0010] The pressurized to non-pressurized water diversion tunnel of the utility model has a reasonably designed geometric feature of the gradient section, the gradient section is tangentially connected to the pressurized section and the non-pressurized section, and the water flow transitions smoothly from the pressurized section to the gradient section to the non-pressurized section, thereby avoiding the turbulence of the water flow; the diameter of the gradient section gradually increases along the direction of the water flow, so that the water flow velocity is slowed down, the water flow flows smoothly, the water level is lowered, the water pressure on the top of the tunnel is reduced, and the service life of the tunnel is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a longitudinal sectional schematic diagram of the gradual change section of the present utility model.

[0012] Figure 2 is a schematic diagram of a piecewise function

[0013] Figure markings: 1. Cave top contour line, 2. Cave bottom contour line, 3. Gradual section, 4. Pressure section, 5. No pressure section, 6. Segmentation point. DETAILED DESCRIPTION

[0014] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0015] See also Figure 1 The utility model proposes a pressurized to non-pressurized water diversion tunnel, comprising: a pressurized section 4 and a non-pressurized section 5. The pressurized section 4 is connected to the upstream water source, and the non-pressurized section 5 is connected to the downstream water use area. The pressurized section 4 and the non-pressurized section 5 are smoothly connected by a gradient section 3. The diameter of the upstream end of the gradient section 3 is equal to the diameter of the pressurized section 4, and the diameter of the downstream end of the gradient section 3 is equal to the diameter of the non-pressurized section 5. The diameter of the pressurized section 4 is smaller than the diameter of the non-pressurized section 5, and the diameter of the gradient section 3 gradually increases along the direction of water flow.

[0016] The longitudinal section of the gradual change section 3 along the water flow direction forms a cave top contour line 1 and a cave bottom contour line 2, and the vertical distance between the cave top contour line 1 and the cave bottom contour line 2 gradually increases along the water flow direction.

[0017] See also Figure 2 , the cave top contour line 1 conforms to the piecewise function The shape of the formula, where d1 is the diameter of the pressure section 4, d2 is the diameter of the non-pressure section 5, L is the length of the gradient section 3, and a and b satisfy To ensure that the diameter of the transition section 3 gradually increases along the water flow direction and has physical significance, a>0, the cave top contour line 1 of the transition section 3 is tangent to the pressure section 4 and the non-pressure section 5, and the segmentation point 6 of the piecewise function of the cave top contour line 1 is the tangent point, so that the water flow transition in the transition section 3 is smooth. The cave bottom contour line 2 is a horizontal straight line segment of length L.

[0018] In some embodiments, the cave top contour line 1 conforms to the piecewise function The shape of the formula, where d1 is the diameter of the pressure section 4, d2 is the diameter of the non-pressure section 5, and L is the length of the gradient section 3. And a and b satisfy The curvature radius of the two segments of the piecewise function to which the cave top contour line 1 conforms is the same.

[0019] After the water flows into the pressurized to non-pressurized water diversion tunnel, when the water flows from the pressurized section 1 into the gradient section 3, the water flow transition is smooth because the pressurized section and the gradient section 3 are tangentially connected, and as the diameter of the gradient section 3 increases, the water velocity decreases and the water level becomes lower; when the water flows from the gradient section 3 into the non-pressurized section 5, the gradient section 3 is tangentially connected to the non-pressurized section 5, the water flow transition is smooth, the water level is low, and the pressure on the tunnel top is small, which increases the service life of the tunnel.

Claims

1. A pressure-to-no-pressure diversion tunnel, comprising a pressure section and a no-pressure section, wherein the pressure section is connected to an upstream water source and the no-pressure section is connected to a downstream water source, characterized in that: The pressure section and the pressure-free section are smoothly connected by a gradient section. The diameter of the upstream end of the gradient section is equal to the diameter of the pressure section, and the diameter of the downstream end of the gradient section is equal to the diameter of the pressure-free section. The diameter of the pressure section is smaller than the diameter of the pressure-free section, and the diameter of the gradient section gradually increases along the direction of water flow.

2. The pressurized to non-pressurized water diversion tunnel according to claim 1 is characterized in that: The longitudinal section of the gradual change section along the water flow direction forms a cave top contour line and a cave bottom contour line, and the vertical distance between the cave top contour line and the cave bottom contour line gradually increases along the water flow direction.

3. The pressurized to non-pressurized water diversion tunnel according to claim 2 is characterized in that: The cave top contour line conforms to the piecewise function The shape of the formula, where d1 is the diameter of the pressure section, d2 is the diameter of the non-pressure section, L is the length of the gradient section, and a and b satisfy The cave top contour line of the gradual section is tangently connected to the pressure section and the non-pressure section.

4. The pressurized to non-pressurized water diversion tunnel according to claim 2 is characterized in that: The cave bottom contour line is a horizontal straight line segment with a length of L.

5. The pressurized to non-pressurized water diversion tunnel according to claim 2 is characterized in that: The cave top contour line conforms to the piecewise function The shape of the formula, where d1 is the diameter of the pressure section, d2 is the diameter of the non-pressure section, and L is the length of the gradient section.

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