Method for determining arch sealing temperature of arch dam of sandy river in cold region

Abstract

The invention discloses a method for determining the arch sealing temperature of an arch dam in a sandy river in a cold region, which comprises the following steps of: respectively calculating stable temperature fields in an initial sand blocking stage and a normal operation stage, determining the arch sealing temperature on the basis of a stable temperature field result in the initial sand blocking stage, further determining a temperature load, and carrying out arch dam shape optimization design by adopting an arched girder partial load method. And obtaining a recommended arch dam shape, rechecking the stress state of the recommended arch dam shape according to the temperature load in the normal operation period, and evaluating the reasonability of the arch sealing temperature. The method better conforms to the actual situation of sandy rivers in cold regions, and basic load conditions are laid for determining the economic and reasonable arch dam body type.

Description

Technical Field

[0001] The invention relates to the technical field of arch dam load design, and is particularly suitable for a method for determining the sealing temperature of an arch dam on a sandy river in cold regions. Background Art

[0002] The arch dam is a typical spatial shell structure. Temperature load is one of its main loads. The arch sealing temperature is the benchmark condition for determining the temperature load. Therefore, it is very important to determine the arch sealing temperature of the arch dam. For arch dams in cold regions, the temperature drop load of the arch dam is large in the low temperature season. A lower arch sealing temperature is conducive to reducing the temperature drop load. However, for reservoirs on sandy rivers, the siltation layer in front of the dam gradually thickens with the increase of operation time, which will increase the water temperature of the reservoir upstream of the arch dam and the stable temperature of the arch dam during operation. At this time, the lower arch sealing temperature will cause the temperature rise load in the high temperature season to increase. Since the siltation morphology in front of the arch dam built on the sandy rivers in cold regions has experienced a dynamic evolution from no siltation in the initial stage of sediment interception to siltation to the designed siltation elevation during normal operation, its arch sealing temperature and temperature load are usually calculated according to the arch dam on the clear water river. This is very different from the actual situation of the arch dam on the sandy rivers in cold regions during operation, and there is obvious irrationality. Therefore, for arch dams on sandy rivers in cold regions, how to quickly and accurately determine their arch sealing temperature is one of the problems that need to be solved urgently. Summary of the invention

[0003] The present invention aims to provide a method for determining the sealing temperature of an arch dam on a sandy river in a cold region, which is used to quickly and accurately determine the sealing temperature of an arch dam on a sandy river in a cold region.

[0004] To achieve the above object, the present invention adopts the following technical solutions: The method for determining the sealing temperature of an arch dam on a sandy river in a cold region according to the present invention comprises the following steps: S1, collect hydrological data, meteorological data, multi-year measured ground temperature data, reservoir capacity relationship curve and operation and dispatching data of the arch dam site to be built; S2, using a one-dimensional reservoir water temperature numerical analysis method, calculate the arch dam upstream reservoir water temperature in the initial stage of sediment interception and normal operation of the arch dam; S3, calculate the water temperature of the reservoir downstream of the arch dam according to the empirical formula; S4. Determine the multi-year average temperature and multi-year average ground temperature of the dam site area based on meteorological data and geological survey data; S5: Determine the radiation temperature rise of the upstream dam surface and the downstream dam surface caused by solar radiation based on the long-term solar radiation data of the dam site, the topography of the dam site, the shape of the arch dam and the surface absorption coefficient of the arch dam; S6, select the typical section of the arch dam crown beam and calculate the stable temperature field of the typical section of the arch dam in the initial stage of sediment retention; S7, calculate the average temperature of the stable temperature field of each characteristic elevation of the typical section of the arch dam in the initial stage of sediment retention, consider the 1~3℃ overcooling, and preliminarily formulate the sealing temperature of the arch dam; S8, according to the temperature load of the arch dam in the initial stage of sediment retention, the arch dam shape optimization design is carried out by using the arch-beam load sharing method to obtain the recommended arch dam shape; S9, calculate the stable temperature field of the typical section of the arch dam during normal operation; S10, calculating the average temperature of the stable temperature field at each characteristic elevation of the arch dam's typical section during normal operation, and using the arch sealing temperature proposed in step S7 to calculate the temperature load at each characteristic elevation of the arch dam during normal operation; S11: According to the temperature loads of various characteristic elevations of the arch dam during normal operation, review the stress state of the arch dam shape recommended in step S8 and evaluate the rationality of the arch closure temperature.

[0005] Furthermore, step S6 calculates the stable temperature field of the typical section of the arch dam in the initial stage of sediment retention based on the water temperature of the reservoir upstream of the arch dam, the water temperature downstream of the arch dam, the multi-year average air temperature in the dam site area, the multi-year average ground temperature in the dam site area, the radiation temperature rise of the upstream dam surface and the radiation temperature rise of the downstream dam surface.

[0006] Furthermore, step S9 calculates the stable temperature field of a typical section of the arch dam during normal operation based on the water temperature of the reservoir upstream of the arch dam, the water temperature downstream of the arch dam, the multi-year average air temperature in the dam site, the multi-year average ground temperature in the dam site, the radiation temperature rise of the upstream dam surface, and the radiation temperature rise of the downstream dam surface.

[0007] Furthermore, the proposed sealing arch temperature in step S7 should consider the ultra-cold temperature that is 1~3℃ lower than the stable temperature field.

[0008] Furthermore, in step S11, it is checked whether the stress of the arch dam shape recommended in step S8 meets the requirements. If so, the arch sealing temperature proposed in step S7 is reasonable. Otherwise, it is checked whether there is room for adjustment of the arch sealing temperature. If so, the arch sealing temperature is adjusted; if not, the recommended arch dam shape is adjusted.

[0009] The advantage of the present invention is that it provides a technical method for determining the sealing temperature of arch dams in many rivers in cold regions by "predicting the sealing temperature of the arch in the initial stage of sand interception and rechecking the sealing temperature during normal operation". The stable temperature fields in the initial stage of sand interception and the normal operation are calculated respectively. According to the calculation results of the stable temperature field in the initial stage of sand interception, the sealing temperature is proposed considering the super-cold of 1 to 3°C, and then the corresponding temperature load in the initial stage of sand interception is determined. The arch-beam load-sharing method is used to carry out the optimal design of the arch dam shape to obtain the recommended arch dam shape. According to the stable temperature field in the normal operation period, based on the proposed sealing temperature, the corresponding temperature load in the normal operation period is obtained, and the stress state of the recommended arch dam shape is rechecked, and then the rationality of the sealing temperature is evaluated. The method of the present invention is scientific and reasonable, and is more in line with the actual situation of sandy rivers in cold regions. It lays a basic load condition for determining an economically reasonable arch dam shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The present invention is a flowchart of the method. DETAILED DESCRIPTION

[0011] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] like Figure 1 As shown, the method for determining the sealing temperature of an arch dam on a sandy river in a cold region according to the present invention comprises the following steps: S1, collect hydrological data, meteorological data, multi-year measured ground temperature data, reservoir capacity relationship curve and operation scheduling data of the arch dam site to be built.

[0013] Hydrological and meteorological data include temperature, cloud cover, evaporation, wind speed, solar radiation, inflow, outflow, incoming water temperature, and incoming sediment content.

[0014] S2, based on the hydrological data, meteorological data, multi-year measured ground temperature data, reservoir capacity relationship curve and operation dispatching data collected in step S1, a one-dimensional reservoir water temperature numerical analysis method is used to calculate the water temperature of the reservoir upstream of the arch dam in the initial stage of arch dam sediment interception and the normal operation period. Among them, the sediment deposition in front of the dam is not considered in the initial stage of sediment interception, that is, there is no sediment deposition in front of the dam at this time. The sediment deposition in front of the dam is considered in the normal operation period, that is, the sediment deposition in front of the dam has reached the design elevation in the normal operation period.

[0015] S3. Calculate the water temperature of the reservoir downstream of the arch dam according to the empirical formula recommended in the Code for Design of Concrete Arch Dams (SL282-2018).

[0016] S4. Determine the annual average air temperature and annual average ground temperature in the dam site area.

[0017] Average annual temperature , where T ai is the average temperature of the ith month.

[0018] S5, based on the long-term solar radiation data of the dam site, taking into account the topography of the arch dam site, the shape of the arch dam and the surface absorption coefficient of the arch dam, determine the radiation temperature rise above the upstream dam surface water level and the radiation temperature rise above the downstream dam surface water level caused by solar radiation .

[0019] S6, calculate the stable temperature field of the arch dam's typical section at the initial stage of sediment interception based on the water temperature of the upstream reservoir of the arch dam, the water temperature of the downstream water of the arch dam, the multi-year average air temperature of the dam site, the multi-year average ground temperature of the dam site, the radiation temperature rise of the upstream dam surface and the radiation temperature rise of the downstream dam surface. The arch dam's typical section is the arch crown beam typical section.

[0020] S7, calculate the average temperature of the stable temperature field of each characteristic elevation of the typical section of the arch dam in the initial stage of sediment retention, and preliminarily formulate the sealing temperature of the arch dam. The proposed sealing temperature should take into account a certain super-cold temperature, which is generally 1-3℃ based on previous engineering experience.

[0021] Temperature load △T of each characteristic elevation of arch dam in the initial stage of sediment retention mi and △T di , and its calculation formula is as follows: (Formula 1) (Formula 2) (Formula 3) (Formula 4) (Formula 5) (Formula 6) (Formula 7) (Formula 8) (Formula 9) (Formula 10) (Formula 11) (Formula 12) (Formula 13) (Formula 14) (Formula 15) (Formula 16) Where: p is the temperature variation period in months, and its value is 12.

[0022] L is the thickness of the dam, in meters (m).

[0023] is the thermal conductivity of concrete, which is taken as 3.24m 2 / moon.

[0024] It is the initial phase of the annual temperature change process, in months. The value is 6.5 for areas with latitudes above 30° and 6.7 for areas with latitudes below 30°.

[0025] It is the phase difference of the annual periodic variation of the upstream and downstream dam surface temperatures, in months.

[0026] A i , A e It is the annual variation of the multi-year average temperature of the upstream and downstream dam surfaces, in ℃.

[0027] The calculation time point of the most unfavorable combination of temperature loads, in months. Usually the value is 7.5 (meaning mid-July) or 8.0 (meaning the end of August) to calculate the corresponding temperature rise value. , , change the sign to calculate the corresponding temperature drop value , ; , , , To calculate the parameters, use formula (9) to formula (12) to calculate respectively.

[0028] T m0i is the sealing temperature of the upstream arch dam; T d0i is the sealing temperature of the downstream arch dam. uwi is the reservoir water temperature at the initial stage of sediment trapping, T a is the annual average temperature of the dam site, ΔT ua is the radiation temperature rise above the upstream dam surface water level, T dwi is the water temperature of the reservoir downstream of the arch dam, ΔT da It is the radiation temperature rise above the downstream dam surface water level.

[0029] S8. Calculate the temperature load of each characteristic elevation of the arch dam at the initial stage of sediment retention according to formula (3) and formula (6), and use the arch-beam load sharing method to optimize the arch dam shape and obtain the recommended arch dam shape.

[0030] S9. Based on the water temperature of the reservoir upstream of the arch dam during normal operation, the water temperature of the water downstream of the arch dam, the multi-year average air temperature in the dam site area, the multi-year average ground temperature in the dam site area, the radiation temperature rise of the upstream dam surface and the radiation temperature rise of the downstream dam surface, a one-dimensional numerical analysis method is used to calculate the water temperature of the reservoir upstream of the arch dam during normal operation, and the stable temperature field of the typical section of the arch dam during normal operation is calculated.

[0031] S10, calculate the upstream and downstream dam surface temperatures at each characteristic elevation of the arch dam's typical sections during normal operation. Use the arch sealing temperature proposed in step S7 to calculate the temperature loads at each characteristic elevation of the arch dam during normal operation according to formulas (3) and (6).

[0032] S11: Use the temperature loads of each characteristic elevation of the arch dam during normal operation to review the stress state of the arch dam shape recommended in step S8 and evaluate the rationality of the arch closure temperature.

[0033] If the stress of the arch dam shape recommended in step S8 meets the requirements, the arch sealing temperature proposed in step S7 is reasonable; if the stress of the arch dam shape recommended in step S8 does not meet the requirements, check whether there is room for adjustment of the arch sealing temperature. If so, adjust the arch sealing temperature; if not, optimize and adjust the recommended arch dam shape.

[0034] Generally speaking, the arch sealing temperature is taken with reference to the stable temperature field of the dam body, which is usually 1 to 3°C lower than the stable temperature field of the typical elevation of the dam body. This 1 to 3°C is the super-cold temperature of the dam site to be built determined based on engineering experience, and is also the adjustment space for the arch sealing temperature.

Claims

1. A method for determining the sealing temperature of an arch dam on a sandy river in a cold region, characterized in that: The following steps are involved: S1, collect hydrological data, meteorological data, multi-year measured ground temperature data, reservoir capacity relationship curve and operation and dispatching data of the arch dam site to be built; S2, using a one-dimensional reservoir water temperature numerical analysis method, calculate the arch dam upstream reservoir water temperature in the initial stage of sediment interception and normal operation of the arch dam; S3, calculate the water temperature of the reservoir downstream of the arch dam according to the empirical formula; S4, determine the multi-year average air temperature and multi-year average ground temperature in the dam site area; S5: Determine the radiation temperature rise of the upstream dam surface and the downstream dam surface caused by solar radiation based on the long-term solar radiation data of the dam site, the topography of the dam site, the shape of the arch dam and the surface absorption coefficient of the arch dam; S6, select the typical section of the arch dam crown beam and calculate the stable temperature field of the typical section of the arch dam in the initial stage of sediment retention; S7, calculate the average temperature of the stable temperature field of each characteristic elevation of the typical section of the arch dam in the initial stage of sediment retention, and preliminarily formulate the sealing temperature of the arch dam; S8, calculate the temperature load of the arch dam in the initial stage of sediment retention, use the arch-beam load sharing method to carry out the optimal design of the arch dam shape, and obtain the recommended arch dam shape; S9, calculate the stable temperature field of the typical section of the arch dam during normal operation; S10, calculating the upstream and downstream dam surface temperatures and average temperatures of each characteristic elevation of a typical section of the arch dam during normal operation, and using the arch sealing temperature proposed in step S7 to calculate the temperature load of each characteristic elevation of the arch dam during normal operation; S11: According to the temperature loads of various characteristic elevations of the arch dam during normal operation, review the stress state of the arch dam shape recommended in step S8 and evaluate the rationality of the arch closure temperature.

2. The method for determining the sealing temperature of an arch dam on a sandy river in a cold region according to claim 1 is characterized in that: Step S6 calculates the stable temperature field of the typical section of the arch dam in the initial stage of sediment retention based on the water temperature of the reservoir upstream of the arch dam, the water temperature downstream of the arch dam, the multi-year average air temperature in the dam site, the multi-year average ground temperature in the dam site, the radiation temperature rise of the upstream dam surface and the radiation temperature rise of the downstream dam surface.

3. The method for determining the sealing temperature of an arch dam on a sandy river in a cold region according to claim 1, characterized in that: Step S9 calculates the stable temperature field of a typical section of the arch dam during normal operation based on the water temperature of the reservoir upstream of the arch dam, the water temperature downstream of the arch dam, the multi-year average air temperature in the dam site, the multi-year average ground temperature in the dam site, the radiation temperature rise of the upstream dam surface, and the radiation temperature rise of the downstream dam surface.

4. The method for determining the sealing temperature of an arch dam on a sandy river in cold regions according to claim 1 is characterized in that: The proposed sealing arch temperature in step S7 should take into account the ultra-cold temperature that is 1~3℃ lower than the stable temperature field.

5. The method for determining the sealing temperature of an arch dam on a sandy river in cold regions according to claim 1 is characterized in that: In step S11, check whether the arch dam shape stress recommended in step S8 meets the requirements. If so, the arch sealing temperature proposed in step S7 is reasonable. Otherwise, check whether there is room for adjustment of the arch sealing temperature. If so, adjust the arch sealing temperature; if not, adjust the recommended arch dam shape.

Images