Low-impact diversion tunnel based on gradual elevation rise and contour line model construction method thereof

Abstract

The low-impact diversion tunnel comprises a low-top section and a high-top section, the low-top section is communicated with an upstream water source, the high-top section is communicated with a downstream water using area, the low-top section and the high-top section are smoothly connected through a transition section, and the transition section is communicated with the low-top section. The top elevation of the upstream end of the transition section is equal to that of the low-top section, the top elevation of the downstream end of the transition section is equal to that of the high-top section, the top elevation of the low-top section is smaller than that of the high-top section, and the top elevation 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 low-top section and the high-top section, water flow is transitionally and smoothly connected from the low-top section to the transition section to the high-top section, and the disorder phenomenon of the water flow is avoided; the top elevation 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 invention relates to the field of water conservancy and hydropower engineering, and in particular to a method for constructing a low-impact water diversion tunnel and a contour line model thereof based on gradually rising elevation. Background Art

[0002] The diversion tunnel is a water conveyance structure that diverts the power generation water from the upstream reservoir to the vicinity of the power plant. It can be divided into non-pressure tunnels and pressure tunnels according to hydraulic conditions. Non-pressure tunnels mostly adopt a gate-shaped cross-section, and the water flow in the tunnel is an open flow state, while pressure tunnels mostly adopt a horseshoe-shaped or circular cross-section, and the water flow in the tunnel is a full-tunnel pressurized flow state.

[0003] At present, the overall layout of a hydropower station consists of an upstream water intake building, a water diversion pressure tunnel, a surge chamber (surge well), a pressure steel pipe, a plant, and a downstream river channel. When the water passes through the water diversion pressure tunnel, the tunnel is filled with water flow, and the top of the tunnel is subject to a certain amount of water pressure. There is no free water surface in the pressure tunnel, and the water flow pattern is better. However, the water pressure in the tunnel is high, and hard rocks are required to resist the water pressure, otherwise it is not economical. Pressure tunnels are suitable for conditions with good geological conditions. However, due to the complex environmental conditions and working mechanisms of hydraulic high-pressure water diversion tunnels, there are still many problems that have not been well solved in terms of crack spacing and width after cracking of the tunnel lining, high-pressure internal water seepage and water load, and calculation and analysis methods. If the traditional pressure water diversion tunnel water delivery method can be changed to non-pressure open channel water delivery, it will avoid the problems of long pressure tunnels, difficult excavation, or the inability to excavate pressure tunnels due to complex geology. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a low-impact water diversion tunnel based on gradually rising elevation and a method for constructing a contour line model thereof, comprising a short-top section connected to an upstream water source and a high-top section connected to a downstream water use area, characterized in that the short-top section and the high-top section are smoothly connected through a gradient section, the top elevation of the upstream end of the gradient section is equal to the top elevation of the short-top section, the top elevation of the downstream end of the gradient section is equal to the top elevation of the high-top section, the top elevation of the short-top section is lower than the top elevation of the high-top section, and the top elevation of the gradient section gradually increases along the water flow direction; the top contour surface of the gradient section is tangently connected to the top contour surfaces of the short-top section and the high-top section, respectively.

[0005] Furthermore, the water diversion tunnel is longitudinally sectioned along the water flow direction to form a tunnel top contour line and a tunnel bottom contour line;

[0006] The cave top contour shape is expressed as a piecewise function

[0007] The shape of 1 is the top elevation of the short top segment, d 2is the top elevation of the high top segment, L is the length of the gradient segment, x is the distance from the starting position of the gradient segment, and a is The radius of the curve at The relationship between a and b satisfies

[0008] Furthermore, the cave bottom contour line is a horizontal straight line segment with a length of L.

[0009] Furthermore, the

[0010] Furthermore, the method for constructing the top contour line of the water diversion tunnel comprises the following steps:

[0011] S1. Establish a coordinate system: establish a rectangular coordinate system with the starting point of the top elevation of the gradient segment as the origin O, x is the length from the starting position of the gradient segment, and y is the top elevation of the gradient segment at point x.

[0012] S2. Assume the expression: The top contour surface of the gradual section is tangent to the top contour surface of the short top section and the top contour surface of the high top section respectively. Therefore, the top contour line of the gradual section is composed of two arcs, including arc 1 and arc 2. Arc 1 meets a is the radius of the circle on which arc 1 lies, and arc 2 conforms to b is the radius of the circle where arc 2 lies.

[0013] S3, simultaneous expression: The short top segment and the high top segment are smoothly connected by the gradient segment, and the top of the gradient segment is smoothly transitioned, so arc 1 and arc 2 are tangently connected, the distance between the centers of arc 1 and arc 2 is the sum of the radii of the circles where arc 1 and arc 2 are located, the center coordinates of arc 1 are (0, a), and the center coordinates of arc 2 are (L, b), that is, Arranged

[0014] S4. Calculate the connection point of arc 1 and arc 2: The straight line expression passing through arc 1 and arc 2 is The straight line passing through arc 1 and arc 2 is combined with arc 1 or arc 2 to obtain the connection point of arc 1 and arc 2. The horizontal coordinate of the connection point is a positive number, and the coordinate of the connection point is

[0015]

[0016] S5. The shape of the cave roof contour conforms to the shape of the piecewise function: piecewise function

[0017] Where d 1 is the top elevation of the short top segment, d 2 is the top elevation of the high top segment, L is the length of the gradient segment, x is the distance from the starting position of the gradient segment, and a is The radius of the curve at The relationship between a and b satisfies

[0018] The beneficial effects of the present invention are as follows:

[0019] The method for constructing a low-impact water diversion tunnel based on gradually rising elevation and its contour line model of the present invention reasonably designs the geometric features of the gradient section, the gradient section is tangently connected to the short top section and the high top section, and the water flow transitions smoothly from the short top section to the gradient section to the high top section, thereby avoiding the turbulence of the water flow; the top elevation 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 water diversion tunnel is reduced, and the service life of the tunnel is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a longitudinal sectional schematic diagram of the gradual change section of the present invention.

[0021] Figure 2 It is a schematic diagram of a piecewise function.

[0022] Figure numerals: 1. Cave top contour line, 2. Cave bottom contour line, 3. Gradient segment, 4. Low top segment, 5. High top segment, 6. Connection point. DETAILED DESCRIPTION

[0023] 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.

[0024] See also Figure 1 The present invention proposes a method for constructing a low-impact water diversion tunnel and its contour line model based on gradually rising elevation, including: a short top section 4 connected to an upstream water source and a high top section 5 connected to a downstream water use area, the short top section 4 and the high top section 5 are smoothly connected through a gradient section 3, the top elevation of the upstream end of the gradient section 3 is equal to the top elevation of the short top section 4, the top elevation of the downstream end of the gradient section 3 is equal to the top elevation of the high top section 5, the top elevation of the short top section 4 is lower than the top elevation of the high top section 5, and the top contour surface of the gradient section 3 is tangently connected to the top contour surface of the short top section 4 and the top contour surface of the high top section 5. The top elevation of the gradient section 3 gradually increases along the water flow direction.

[0025] The longitudinal section of the water diversion tunnel along the water flow direction forms a tunnel top contour line 1 and a tunnel bottom contour line 2, and the vertical distance between the tunnel top contour line 1 and the tunnel bottom contour line 2 gradually increases along the water flow direction.

[0026] See also Figure 2 , the shape of the cave top contour line 1 is expressed as a piecewise function The shape of1 is the top elevation of the short top segment 4, d 2 is the top elevation of high top segment 5, L is the length of gradient segment 3, x is the distance from the starting position of gradient segment 3, a is The radius of the curve at The curve radius at which a and b meet In order to satisfy the requirement that the top elevation of the gradient section 3 gradually increases along the direction of water flow and has physical significance, a>0, the cave top contour line 1 of the gradient section 3 is tangently connected to the short top section 4 and the high top section 5, and the connection point 6 of the piecewise function of the cave top contour line 1 is the tangent point, and the water flow transition in the gradient section 3 is smooth.

[0027] The cave bottom contour line 2 is a horizontal straight line segment with a length of L.

[0028] The method for constructing the top contour line 1 of a water diversion tunnel comprises the following steps:

[0029] S1. Establish a coordinate system: establish a rectangular coordinate system with the starting point of the top elevation of the gradient segment 3 as the origin O, where x is the length from the starting position of the gradient segment 3, and y is the top elevation of the gradient segment 3 at point x.

[0030] S2, suppose the expression: the top contour surface of the gradient section 3 is tangently connected to the top contour surface of the low top section 4 and the top contour surface of the high top section 5, so the top contour line 1 of the gradient section 3 is composed of two arcs, including arc 1 and arc 2, and arc 1 meets a is the radius of the circle on which arc 1 lies, and arc 2 conforms to b is the radius of the circle where arc 2 lies.

[0031] S3, simultaneous expression: The short top segment 4 and the high top segment 5 are smoothly connected by the gradient segment 3, and the top of the gradient segment 3 has a smooth transition, so arc 1 and arc 2 are tangently connected, the distance between the centers of arc 1 and arc 2 is the sum of the radii of the circles where arc 1 and arc 2 are located, the center coordinates of arc 1 are (0, a), and the center coordinates of arc 2 are (L, b), that is, Arranged

[0032] S4. Calculate the connection point of arc 1 and arc 2: The straight line expression passing through arc 1 and arc 2 is The straight line passing through arc 1 and arc 2 is combined with arc 1 or arc 2 to obtain the connection point of arc 1 and arc 2. The horizontal coordinate of the connection point is a positive number, and the coordinate of the connection point is

[0033]

[0034] S5. The shape of the cave top contour line 1 conforms to the shape of the piecewise function: piecewise function

[0035] Where d 1 is the top elevation of the short top segment 4, d 2 is the top elevation of high top segment 5, L is the length of gradient segment 3, x is the distance from the starting position of gradient segment 3, a is The radius of the curve at The relationship between a and b satisfies

[0036] In some embodiments, the radius of the circle where arc 1 lies is equal to the radius of the circle where arc 2 lies, and a and b satisfy The calculation can be obtained The shape of the cave top contour line 1 is expressed as a piecewise function in

[0037] After the water flows into the low-impact water diversion tunnel based on gradual elevation increase and the method for constructing its contour line model, when the water flows from the short top section 1 into the gradient section 3, because the short top section and the gradient section 3 are tangently connected, the water flow transition is gentle, and as the elevation of the top 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 high top section 5, the gradient section 3 is tangently connected to the high top section 5, the water flow transition is gentle, the water level is low, and the pressure on the top of the water diversion tunnel is small, which increases the service life of the tunnel.

Claims

1. A low-impact water diversion tunnel based on gradual elevation increase, comprising a low-top section connected to an upstream water source and a high-top section connected to a downstream water use area, characterized in that: The short top section and the high top section are smoothly connected by a gradient section, the top elevation of the upstream end of the gradient section is equal to the top elevation of the short top section, the top elevation of the downstream end of the gradient section is equal to the top elevation of the high top section, the top elevation of the short top section is lower than the top elevation of the high top section, and the top elevation of the gradient section gradually increases along the water flow direction; the cave top contour surface of the gradient section is tangently connected to the cave top contour surface of the short top section and the cave top contour surface of the high top section respectively.

2. The water diversion tunnel according to claim 1, characterized in that: The water diversion tunnel is longitudinally sectioned along the water flow direction to form a tunnel top contour line and a tunnel bottom contour line; The cave top contour shape is expressed as a piecewise function The shape of the formula is, where d1 is the top elevation of the short top segment, d2 is the top elevation of the high top segment, L is the length of the gradient segment, x is the distance from the starting position of the gradient segment, and a is The radius of the curve at The curve radius at the point where a and b satisfy the relationship 3. The water diversion tunnel according to claim 2, characterized in that: The cave bottom contour line is a horizontal straight line segment with a length of L.

4. The water diversion tunnel according to claim 2, characterized in that: Said 5. The method for constructing the top contour line of a water diversion tunnel according to claim 1, characterized in that: The following steps are involved: S1. Establish a coordinate system: establish a rectangular coordinate system with the starting point of the top elevation of the gradient segment as the origin O, where x is the length from the starting position of the gradient segment, and y is the top elevation of the gradient segment at point x; S2. Assume the expression: The top contour surface of the gradual section is tangent to the top contour surface of the short top section and the top contour surface of the high top section respectively. Therefore, the top contour line of the gradual section is composed of two arcs, including arc 1 and arc 2. Arc 1 meets a is the radius of the circle on which arc 1 lies, and arc 2 conforms to b is the radius of the circle where arc 2 lies; S3, simultaneous expression: The short top segment and the high top segment are smoothly connected by the gradient segment, and the top of the gradient segment is smoothly transitioned, so arc 1 and arc 2 are tangently connected, the distance between the centers of arc 1 and arc 2 is the sum of the radii of the circles where arc 1 and arc 2 are located, the center coordinates of arc 1 are (0, a), and the center coordinates of arc 2 are (L, b), that is, Arranged S4. Calculate the connection point of arc 1 and arc 2: The straight line expression passing through arc 1 and arc 2 is The straight line passing through arc 1 and arc 2 is combined with arc 1 or arc 2 to obtain the connection point of arc 1 and arc 2. The horizontal coordinate of the connection point is a positive number, and the coordinate of the connection point is S5. The shape of the cave roof contour conforms to the shape of the piecewise function: piecewise function Where d1 is the top elevation of the short top segment, d2 is the top elevation of the high top segment, L is the length of the gradient segment, x is the distance from the starting position of the gradient segment, and a is The radius of the curve at The curve radius at the point where a and b satisfy the relationship

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