Reservoir immersion prediction method

Abstract

The invention discloses a reservoir immersion prediction method, belongs to the technical field of reservoir immersion prediction, and can solve the problem that an existing reservoir immersion prediction method does not consider additional subsidence generated after loess immersion saturation collapse, so that the applicability is poor. The method comprises the steps that S1, the stratum type of a reservoir stratum is determined, and the collapsibility of the reservoir stratum is determined according to the stratum type; s2, determining the buried depth of the critical underground water level immersed in the reservoir according to the collapsibility; and S3, determining the groundwater heap water level after the reservoir stores water, and performing reservoir immersion prediction according to the groundwater heap water level and the critical groundwater level burial depth. The method is used for reservoir immersion prediction.

Description

Technical Field

[0001] The invention relates to a reservoir submergence prediction method and belongs to the technical field of reservoir submergence prediction. Background Art

[0002] Reservoir submergence refers to the phenomenon that the groundwater in the surrounding area of ​​the reservoir is raised due to the water storage of the reservoir, which in turn causes soil salinization and swamping, sinking or damage of building foundations, and water filling or increased water inflow in underground projects and mines. Reservoir submergence prediction is judged by comparing the elevation of the groundwater level after the reservoir is filled with water and the size of the local critical groundwater burial depth. If the elevation of the groundwater level after the reservoir is filled with water is higher than the local critical groundwater burial depth, submergence will occur, otherwise it will not occur. Although the existing reservoir submergence prediction method is suitable for reservoir submergence evaluation in most reservoir strata, it is less applicable to collapsible loess, especially self-weight collapsible loess, because it does not take into account the additional subsidence caused by the saturated collapsing of loess. Summary of the invention

[0003] The present invention provides a reservoir submergence prediction method, which can solve the problem that the existing reservoir submergence prediction method does not consider the additional subsidence caused by saturated collapsing of loess, resulting in poor applicability.

[0004] The present invention provides a reservoir flooding prediction method, the method comprising: S1. determining the formation type of the reservoir formation, and determining the collapse amount of the reservoir formation according to the formation type; S2, determining the critical groundwater level depth of the reservoir according to the collapsibility; S3. Determine the groundwater level after the reservoir is filled with water, and predict the reservoir submergence based on the groundwater level and the critical groundwater level depth.

[0005] Optionally, the determining of the stratum type of the reservoir stratum in S1 specifically includes: Obtain the collapsibility coefficient of reservoir strata; When the collapsible coefficient is greater than or equal to a preset threshold, the reservoir stratum is determined to be a collapsible stratum; otherwise, the reservoir stratum is determined to be a non-collapsed stratum.

[0006] Optionally, the step of determining the collapsibility of the reservoir stratum according to the stratum type in S1 specifically includes: When the reservoir stratum is collapsible, the collapsible amount of the reservoir stratum is determined by water immersion experiment; When the reservoir stratum is a non-collapseable stratum, the collapsible amount of the reservoir stratum is determined to be 0.

[0007] Optionally, the S2 specifically includes: S21. Determine the height of the capillary water rise zone in the soil above the groundwater level at the reservoir and the safety overheight value at the reservoir; S22. Determine the critical groundwater level depth of the reservoir according to the capillary water rise zone height, the safety overheight value and the collapsibility.

[0008] Optionally, the S22 is specifically: The sum of the capillary water rise zone height, the safety overheight value and the collapsibility is taken as the critical groundwater level depth for reservoir immersion.

[0009] Optionally, the step of determining the groundwater level after the reservoir is filled with water in S3 specifically includes: Determine the backwater level elevation after the reservoir is filled; The groundwater level after the reservoir is filled with water is determined according to the backwater level elevation.

[0010] Optionally, the reservoir submergence prediction in S3 according to the groundwater level and the critical groundwater level depth is specifically: When the groundwater level is higher than the critical groundwater level, it is determined that the reservoir is submerged.

[0011] Optionally, the preset threshold is 0.015.

[0012] The beneficial effects that the present invention can produce include: The reservoir submergence prediction method provided by the present invention determines the amount of collapse of the reservoir stratum by the stratum type of the reservoir stratum, and considers the amount of collapse of the reservoir stratum in the prediction of the critical groundwater level burial depth of the reservoir submergence, thereby realizing the optimization of the method for predicting the submergence of a reservoir in a collapsible stratum. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A flow chart of a reservoir flooding prediction method provided by an embodiment of the present invention; Figure 2 A schematic diagram of reservoir submergence prediction for non-collapsed loess strata provided by an embodiment of the present invention; Figure 3 A schematic diagram of reservoir inundation prediction in a collapsible loess area provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The present invention is described in detail below in conjunction with embodiments, but the present invention is not limited to these embodiments.

[0015] The embodiment of the present invention provides a reservoir flooding prediction method, such as Figure 1 As shown, the method includes: S1. Determine the stratigraphic type of the reservoir stratum, and determine the amount of subsidence of the reservoir stratum based on the stratigraphic type.

[0016] Among them, determining the stratigraphic type of the reservoir stratum specifically includes: Obtain the collapsibility coefficient of reservoir strata; When the collapsible coefficient is greater than or equal to a preset threshold, the reservoir stratum is determined to be a collapsible stratum; otherwise, the reservoir stratum is determined to be a non-collapsed stratum.

[0017] Since collapsible soil includes collapsible gravel soil, collapsible sandy soil, collapsible loess, etc., the stratum type in the embodiment of the present invention can be collapsible gravel soil, collapsible sandy soil, collapsible loess, etc., and the embodiment of the present invention does not limit this.

[0018] For ease of description, the embodiment of the present invention takes the collapsible loess stratum type as an example to explain the reservoir submergence prediction method in detail.

[0019] Collapsible loess is a special type of loess that has high strength under natural humidity, but when it is soaked in water, the soil structure is quickly destroyed and significant additional sinking occurs. Its collapsible property is an important basis for evaluating foundation stability and engineering treatment measures.

[0020] Collapsibility coefficient It is the ratio of the collapsible deformation of the loess sample after immersion in water under saturated deadweight pressure to its original height.

[0021] Taking the collapsible loess layer as an example, the above preset threshold may be 0.015.

[0022] In general, if ≥ 0.015, it is judged as collapsible loess; if < 0.015, it is judged as non-collapse loess.

[0023] The method of S1 is to determine the collapsibility of reservoir strata according to the stratum type, specifically including: When the reservoir stratum is collapsible, a water immersion experiment is used to determine the amount of collapse of the reservoir stratum.

[0024] For example, when the reservoir stratum is collapsible loess stratum, the collapsible amount of the collapsible stratum in the submerged area is The specific calculation method and calculation depth can be determined based on the immersion test or the "Building Standards for Collapsible Loess Areas (GB50025-2018)".

[0025] When the reservoir stratum is a non-collapseable stratum, the collapsible amount of the reservoir stratum is determined to be 0.

[0026] S2. Determine the critical groundwater level depth of reservoir submergence based on the amount of wetting.

[0027] Specifically include: S21. Determine the height of the capillary water rise zone in the soil above the groundwater level at the reservoir and the safety excess value at the reservoir.

[0028] First, determine the backwater level elevation after the reservoir is normally filled with water; the backwater level refers to the water surface elevation at a certain section of the reservoir area after the reservoir is filled with water, which is generally higher at the tail of the reservoir and is determined based on the reservoir design or operation data.

[0029] Then determine the height of the capillary water rise zone in the soil above the groundwater level corresponding to the backwater level The height of the capillary water rising zone in the soil can be determined based on the suitable soil moisture content during the crop growth period and the soil moisture content above the groundwater level measured in the field. In salinized areas, the curve of soil salt content changing with depth must also be considered for selection. For towns and residential areas, the height can be determined by comparing the moisture content change curve of the soil above the groundwater level with the natural moisture content of the bearing layer before reservoir water storage, or it can be obtained based on indoor tests of the local soil layer.

[0030] Finally determine the safety super high value For agricultural areas, this value is the thickness of the root layer, which can be obtained by checking specifications or on-site investigations; for towns and residential areas, this value depends on the building load, foundation form and masonry depth, and can be obtained through on-site investigations.

[0031] S22. Determine the critical groundwater level depth for reservoir submergence based on the capillary water rise zone height, safety overheight value and collapsibility.

[0032] Specifically, the sum of the capillary water rise zone height, the safety overheight value and the collapsibility is taken as the critical groundwater level depth of the reservoir.

[0033] Calculate the critical groundwater depth for reservoir submergence . The amount of soil collapse introduced into the reservoir After that, the calculation formula is optimized as follows: ; Where: is the critical groundwater level depth of the reservoir (m); is the height of capillary water rise zone (m); It is a high value for safety; It is the amount of subsidence of reservoir strata in the submerged area.

[0034] S3. Determine the groundwater level after the reservoir is filled with water, and make a reservoir submergence prediction based on the groundwater level and the critical groundwater level depth.

[0035] Among them, determining the groundwater level after the reservoir is filled with water includes: First, determine the backwater level elevation after the reservoir is filled with water; then determine the groundwater level after the reservoir is filled with water based on the backwater level elevation.

[0036] The groundwater high water level refers to the groundwater level in the slope soil after the reservoir is filled with water, which rises with the reservoir water level.

[0037] After obtaining the backwater level elevation after the reservoir is filled, the groundwater level is determined according to the backwater level elevation after the reservoir is filled. According to the "Engineering Geological Survey Code for Hydropower Project Reservoir Area (NB / T 10131-2019)", the groundwater level after water storage can be determined by the geological analogy diagram method, that is, the hydraulic gradient of the reservoir stratum is determined by geological analogy, and a line is drawn from the contact point between the backwater level and the slope according to a certain hydraulic gradient. This line is the corresponding groundwater level. Among them, the hydraulic gradient refers to the slope of water flowing underground.

[0038] The above reservoir submergence prediction is performed based on the groundwater backfill water level and the critical groundwater level burial depth. Specifically, when the groundwater backfill water level is greater than the critical groundwater level burial depth, it is determined that the reservoir is submerged.

[0039] Specifically, compare the groundwater level after water storage. and critical groundwater depth ,like , then the reservoir will be flooded, otherwise it will not be flooded.

[0040] Figure 2 Schematic diagram of reservoir inundation prediction in non-collapsed loess strata; the groundwater backfill line is a line drawn from the contact point between the backwater level and the slope according to a certain stratum hydraulic gradient; the capillary water saturation zone refers to the height above the groundwater backfill line plus the capillary water rise zone. The thickness of the safety super-high zone refers to the thickness above the top of the capillary water saturation zone plus the safety super-high value. The predicted reservoir submergence area refers to the critical groundwater level. The following surface width.

[0041] Figure 3 This is a schematic diagram of reservoir inundation prediction in collapsible loess strata; the collapsibility refers to the height difference between the original topographic line and the topographic line after waterlogging and collapsing.

[0042] Based on the existing standard prediction method, the present invention optimizes the existing critical groundwater level depth prediction formula for reservoir strata such as loess strata with collapsible properties, and increases the collapsible amount of loess after saturation. , realizing the optimization of reservoir inundation prediction method in collapsible loess areas.

[0043] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A reservoir flooding prediction method, characterized in that: The method comprises: S1. determining the formation type of the reservoir formation, and determining the collapse amount of the reservoir formation according to the formation type; S2, determining the critical groundwater level depth of the reservoir according to the collapsibility; S3. Determine the groundwater level after the reservoir is filled with water, and predict the reservoir submergence based on the groundwater level and the critical groundwater level depth.

2. The method according to claim 1, characterized in that Determining the stratum type of the reservoir stratum in S1 specifically includes: Obtain the collapsibility coefficient of reservoir strata; When the collapsible coefficient is greater than or equal to a preset threshold, the reservoir stratum is determined to be a collapsible stratum; otherwise, the reservoir stratum is determined to be a non-collapsed stratum.

3. The method according to claim 2, characterized in that Determining the collapsibility of the reservoir stratum according to the stratum type in S1 specifically includes: When the reservoir stratum is collapsible, the collapsible amount of the reservoir stratum is determined by water immersion experiment; When the reservoir stratum is a non-collapseable stratum, the collapsible amount of the reservoir stratum is determined to be 0.

4. The method according to claim 1, characterized in that The S2 specifically includes: S21. Determine the height of the capillary water rise zone in the soil above the groundwater level at the reservoir and the safety overheight value at the reservoir; S22. Determine the critical groundwater level depth of the reservoir according to the capillary water rise zone height, the safety overheight value and the collapsibility.

5. The method according to claim 4, characterized in that The S22 is specifically: The sum of the capillary water rise zone height, the safety overheight value and the collapsibility is taken as the critical groundwater level depth for reservoir immersion.

6. The method according to claim 1, characterized in that The step of determining the groundwater level after the reservoir is filled with water in S3 specifically includes: Determine the backwater level elevation after the reservoir is filled; The groundwater level after the reservoir is filled with water is determined according to the backwater level elevation.

7. The method according to claim 1, characterized in that The reservoir submergence prediction in S3 is performed according to the groundwater level and the critical groundwater level depth, specifically: When the groundwater level is higher than the critical groundwater level, it is determined that the reservoir is submerged.

8. The method according to claim 2, characterized in that: The preset threshold is 0.015.

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