Multi-stage quantification method for flood control standard of damming dam based on reservoir capacity

Abstract

The application discloses a multi-stage quantification method for flood control standards of barrier dams based on reservoir capacity, and overcomes randomness of experience judgment by establishing a treatment stage division model F(V) based on a critical reservoir capacity threshold, and clarifying treatment stages (single stage and double stage) to be adopted by barrier lakes of different sizes. For barrier lakes with reservoir capacity between 1 million m3 and 10 million m3, the influence of barrier body material composition is considered, so that stage division is more accurate and reliable.

Description

Technical Field

[0001] This invention belongs to the field of emergency response technology for landslide dams in water conservancy projects, specifically involving a multi-stage quantitative method for flood control standards of landslide dams based on reservoir capacity. Background Technology

[0002] A landslide-dammed lake is a lake formed when natural disasters such as earthquakes, torrential rains, and landslides cause landslides that block river channels and impound water. Once a landslide-dammed lake breaches, it generates a massive flood peak, posing a serious threat to the lives and property of people downstream and the safety of critical infrastructure. Currently, landslide-dammed lake management typically involves excavating spillway channels to reduce reservoir capacity and the risk of breach. However, existing methods have several shortcomings: First, there is a lack of clear standards for defining the stages of management: current solutions often rely on experience and lack scientific standards based on reservoir size and the composition of the landslide material. Second, the selection of design flood standards for spillway channels lacks a basis: the selection of design flood standards for spillway channels is arbitrary; standards that are too high lead to long construction times and low rescue efficiency, while standards that are too low may fail to effectively control risks. Third, existing technologies focus primarily on the emergency response stage and lack methods for calculating flood control standards for later restoration and management of the river channel. Therefore, there is an urgent need for a scientific and quantitative method for defining the stages of landslide-dammed lake management and a model for determining design flood standards, providing differentiated management strategies and technical standards for landslide-dammed lakes of different sizes, and improving the efficiency and safety of emergency management of landslide-dammed lakes. Summary of the Invention

[0003] To address the lack of scientific standards for phased management and the arbitrary selection of design flood standards in existing landslide dam management practices, this paper proposes a multi-stage quantitative method for landslide dam flood control standards based on reservoir capacity. This method can: 1) scientifically divide management phases (single-stage and double-stage) according to the reservoir capacity and material composition of the landslide dam; and 2) provide quantitative design flood standards for management projects at different stages, balancing management efficiency and safety, and ensuring effective control of landslide dam risks.

[0004] To achieve the above objectives, this invention provides a multi-stage quantification method for flood control standards of landslide dams based on reservoir capacity, as detailed below:

[0005] A treatment stage division model based on the critical storage capacity threshold is established, as shown in equation (1):

[0006] Equation (1)

[0007] In the formula: V is the reservoir capacity of the landslide dammed lake, in meters. 3 V c1 The first-level critical reservoir capacity threshold is defined as the reservoir capacity of a landslide dammed lake being greater than or equal to V. c1 At that time, a two-stage process was adopted, Stage Ⅰ Stage is the emergency response phase.Ⅱ The recovery and treatment phase; V c2 This is the secondary critical reservoir capacity threshold; when the reservoir capacity of the landslide dammed lake is less than V... c2 When the reservoir capacity of the landslide dam is less than V, a single-stage approach is adopted; when the reservoir capacity of the landslide dam is less than V... c1 , greater than or equal to V c2 At that time, the stage of disposal is determined by the composition of the landslide dam. If the average particle size of the material is less than 20 mm, the excavation of the landslide dam will be less difficult, then Stage Optional Take Stage, otherwise take Stage Ⅰ+Ⅱ .

[0008] Furthermore, the V c1 The value is 1×10 7 m 3 .

[0009] Furthermore, the V c2 The value is 1×10 6 m 3 .

[0010] Furthermore, the emergency response stage Ⅰ The standard calculation model for flood discharge channel design is shown in equation (2):

[0011] Equation (2)

[0012] In the formula: P Ⅰ (V) is the emergency response stage. Ⅰ The spillway is designed for a flood event of once a year.

[0013] Furthermore, the recovery and disposal stage Ⅱ The calculation model for the flood control standard of the river channel is shown in equation (3):

[0014] Equation (3)

[0015] In the formula: P Ⅱ (V) Stage of Recovery and Disposal Ⅱ The flood control standard for the river channel is once a year; P0 is the original flood control standard for the river channel, once a year; max() is the maximum value function.

[0016] Furthermore, the calculation model for the single-stage flood control standard of the small-capacity landslide dam lake is shown in equation (4):

[0017] Equation (4)

[0018] In the formula: P(V) is the single-stage flood control standard, once a year; P0 is the original river channel flood control standard, once a year.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1) Scientific and quantitative approach to the division of disposal stages: By establishing a disposal stage division model F(V) based on the critical reservoir capacity threshold, the disposal stages (single-stage and dual-stage) to be adopted for landslide dammed lakes of different sizes are clarified, overcoming the arbitrariness of relying on experience-based judgment. For landslide dammed lakes with a reservoir capacity between 1 million m³ and 10 million m³, the influence of the material composition of the dammed body is also considered, making the stage division more accurate and reliable.

[0021] 2) Provides quantitative basis for flood standard design of spillway: through the established Stage Ⅰ The design flood standard calculation model for spillway ducts clarifies the design standards for spillway ducts that should be adopted for landslide dammed lakes of different reservoir capacities, balancing disposal efficiency and safety, and avoiding the problems of excessively high standards leading to long construction times or excessively low standards failing to effectively control risks.

[0022] 3) Improved the entire process of handling: The flood standard not only takes into account the need for rapid risk reduction in the emergency response stage (Stage I), but also ensures the technical requirements for restoring the flood discharge capacity of the river and the stability of the residual landslide dam in the recovery and handling stage through the Stage II river flood control standard calculation model. Detailed Implementation

[0023] The technical solutions (including preferred technical solutions) of the present invention will be further described in detail below by listing some optional embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The multi-stage quantification method for flood control standards of landslide dams based on reservoir capacity is as follows:

[0025] The larger the reservoir capacity of a landslide-dammed lake, the higher its risk and the greater the threat to downstream areas. Case studies of over a hundred landslide-dammed lakes demonstrate that the stages of landslide-dammed lake management depend on the risk and degree of damage indicated by its reservoir capacity. When the reservoir capacity of a landslide-dammed lake is greater than or equal to 10 million cubic meters... 3In general, emergency response measures should be implemented quickly to rapidly reduce the capacity of the landslide-dammed lake by establishing an effective spillway. However, due to the large capacity of the landslide-dammed lake, setting the design flood standard for the spillway too high would increase construction time and difficulty, hindering the rapid rescue efforts. Therefore, the handling of landslide-dammed lakes should be divided into an emergency response phase and a recovery phase. The emergency response phase uses a lower design standard to achieve rapid dredging of the landslide-dammed lake; the recovery phase uses a higher flood control standard to ensure the restored river channel's flood discharge capacity and the stability of the remaining landslide dam. When the landslide-dammed lake capacity is greater than or equal to 1 million m³... 3 And less than 10 million m 3 If the material composition of the landslide dam is relatively small, the excavation of the landslide dam will be easier, and the excavation can proceed without phases. If the material composition is relatively large, the excavation will be more difficult, and the excavation will need to be carried out in phases. If the capacity of the landslide dam is less than 1 million cubic meters... 3 If the risk is low, it can be implemented without phases. Based on this, a phase division model for disposal based on the critical storage capacity threshold is established, as shown in equation (1):

[0026] Equation (1)

[0027] In the formula: V is the reservoir capacity of the landslide dammed lake, in meters. 3 V c1 The first-level critical reservoir capacity threshold is set at 1×10-1. 7 m 3 When the reservoir capacity of the landslide dammed lake is greater than or equal to V c1 At that time, a two-stage process was adopted, Stage Ⅰ The Stage is an emergency response phase with the goal of rapidly reducing risks. Ⅱ The recovery and disposal phase aims to restore the original flood discharge capacity of the river channel and ensure the stability of the remaining landslide dam. c2 The secondary critical reservoir capacity threshold is set to 1×10. 6 m 3 When the reservoir capacity of the landslide dammed lake is less than V c2 When the reservoir capacity of the landslide dam is less than V, a single-stage approach is adopted; when the reservoir capacity of the landslide dam is less than V... c1 , greater than or equal to V c2 At that time, the stage of disposal is determined by the composition of the landslide dam. If the average particle size of the material is less than 20 mm, the excavation of the landslide dam will be less difficult, then Stage Optional Take Stage, otherwise take Stage Ⅰ+Ⅱ .

[0028] Among them, the emergency response stage ⅠThe core objective is to quickly establish an effective spillway. The selection of the design flood standard for the spillway needs to be balanced with the efficiency of emergency response measures. A higher design flood standard results in stronger flow energy but also longer construction time, making rapid emergency response difficult. Quantifying the design flood standard for the spillway requires comprehensive consideration of multiple factors, including the reservoir capacity of the landslide dam, the size of the spillway, and its impact on downstream areas. This invention, based on nearly one hundred landslide dam case studies, establishes a Stage for emergency response through flood breach simulation analysis. Ⅰ The standard calculation model for flood discharge channel design is shown in equation (2):

[0029] Equation (2)

[0030] In the formula: P Ⅰ (V) is the emergency response stage. Ⅰ The spillway is designed for a flood event of once a year.

[0031] Recovery and Disposal Stage Ⅱ The core objective is to ensure the restoration of the river's flood discharge capacity and the stability of the remaining landslide dam. This invention relies on dozens of landslide-dammed lake cases after emergency response to ensure the restoration of the river's flood discharge capacity and the stability of the remaining landslide dam. Through inversion analysis, a Stage for the restoration and response phase is established. Ⅱ The calculation model for river flood control standards is shown in equation (3):

[0032] Equation (3)

[0033] In the formula: P Ⅱ (V) Stage of Recovery and Disposal Ⅱ The flood control standard for the river channel is once a year; P0 is the original flood control standard for the river channel, once a year; max() is the maximum value function.

[0034] The calculation model for the single-stage flood control standard of a small reservoir-capacity landslide dammed lake is shown in equation (4):

[0035] Equation (4)

[0036] In the formula: P(V) is the single-stage flood control standard, once a year; P0 is the original river channel flood control standard, once a year.

[0037] The specific embodiments of the present invention are further described below:

[0038] 1. Data collection and storage capacity calculation

[0039] First, topographic data of the landslide dam and its surrounding area were obtained using technologies such as UAV aerial surveying and 3D laser scanning. Second, based on the topographic data and water level observations, the water level-capacity curve of the landslide dam was plotted, and the capacity of the landslide dam was calculated. Finally, the material composition and particle size distribution characteristics of the landslide dam were determined through geophysical exploration and other means.

[0040] 2. Division of Disposal Stages

[0041] Based on the obtained reservoir capacity V of the landslide dammed lake, the disposal stage is determined according to the following criteria:

[0042] When V ≥ 10 million m³, a two-stage treatment is adopted: Stage Ⅰ (Emergency response phase, with the goal of rapidly reducing risks) and Stage Ⅱ (The recovery and disposal phase aims to restore the original flood discharge capacity of the river channel and ensure the stability of the remaining landslide dam.)

[0043] When 1 million m³ ≤ V < 10 million m³, further analysis of the material composition of the landslide dam is required: if the average particle size of the material is less than 20 mm, the excavation is easier and a single-stage treatment can be adopted; if the average particle size of the material is greater than or equal to 20 mm, the excavation is more difficult and a two-stage treatment is required.

[0044] When V < 1 million m³, a single-stage treatment is adopted.

[0045] 3. Determination of flood standard for spillway design

[0046] Based on the determined disposal stage and the reservoir capacity of the landslide dam, the design flood standard for the spillway is determined according to the following criteria:

[0047] Emergency Response Stage Ⅰ Flood standard for spillway design:

[0048] When V ≥ 500 million m³, the design flood standard shall not be lower than once in 20 years;

[0049] When 100 million m³ ≤ V < 500 million m³, the design flood standard is taken as a 10-20 year return period.

[0050] When 10 million m³ ≤ V < 100 million m³, the design flood standard is taken as a 5-10 year return period;

[0051] When 1 million m³ ≤ V < 10 million m³, the design flood standard is taken as a 3-5 year return period.

[0052] Recovery and treatment phase (Stage) Ⅱ River flood control standards:

[0053] When V≥100 million m³, the flood control standard of the river channel shall not be lower than once every 25 years, and shall not be lower than the original flood control standard of the river channel.

[0054] When 10 million m³ ≤ V < 100 million m³, the flood control standard for the river channel shall be a 15-25 year return period, and shall not be lower than the original flood control standard for the river channel.

[0055] When 1 million m³ ≤ V < 10 million m³, the flood control standard for the river channel shall be a 10-15 year return period, and shall not be lower than the original flood control standard for the river channel.

[0056] Flood control standards for small-capacity landslide dammed lakes (Stage):

[0057] When V < 1 million m³, the design flood standard shall not be lower than once every 5 years and shall not be lower than the original flood control standard of the river channel.

[0058] 4. Implementation and Adjustment of the Disposal Plan

[0059] Based on the determined treatment stage and design standards, develop a specific excavation plan for the spillway (including location, cross-sectional shape, longitudinal slope, etc.).

[0060] Application Case: A landslide-dammed lake with a capacity of approximately 300 million cubic meters 3 The material composition has an average particle size of 35 mm. Based on the critical storage capacity-based disposal stage classification model, a two-stage disposal process is required: an emergency disposal stage and a recovery disposal stage. According to the emergency disposal stage... Ⅰ The design flood standard calculation model for the spillway adopts a 20-year flood as the design flood standard during the emergency response phase; based on the recovery and response stage... Ⅱ The calculation model for river flood control standards adopted a 25-year flood as the standard for the emergency recovery phase. Practice has shown that the adoption of the above flood standard has enabled rapid emergency response to landslide dams, reducing the downstream at-risk population from 1.3 million to 270,000. At the same time, it has ensured the stability of the landslide dam and the restoration of the river channel to its normal flood discharge capacity during the landslide dam recovery phase.

[0061] It will be readily understood by those skilled in the art that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, substitutions, improvements, etc., made under the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A multi-stage quantitative method for flood control standards of landslide dams based on reservoir capacity, characterized in that: The quantification method is as follows: A treatment stage division model based on the critical storage capacity threshold is established, as shown in equation (1): Equation (1); In the formula: V The capacity of the landslide-dammed lake is expressed in meters (m). 3 ; V c1 The first-level critical reservoir capacity threshold is defined as the reservoir capacity of a landslide-dammed lake being greater than or equal to... V c1 At that time, a two-stage approach was adopted. Stage Ⅰ This is the emergency response phase. Stage Ⅱ This is the recovery and handling phase; V c2 This is the secondary critical reservoir capacity threshold; when the reservoir capacity of the landslide dammed lake is less than... V c2 At that time, a single-stage approach was adopted. Stage When the reservoir capacity of the landslide dam is less than V c1 Greater than or equal to V c2 At that time, the disposal stage is determined by the composition of the landslide dam. If the average particle size of the material is less than 20mm, the excavation of the landslide dam will be less difficult. Stage Optional Pick Stage Otherwise, take as Stage Ⅰ+Ⅱ ; The V c1 The value is 1×10 7 m 3 The V c2 The value is 1×10 6 m 3 .

2. The multi-stage quantification method for flood control standards of landslide dams based on reservoir capacity as described in claim 1, characterized in that: The emergency response phase Stage Ⅰ The standard calculation model for flood discharge channel design is shown in equation (2): Equation (2); In the formula: P Ⅰ (V) Emergency response phase Stage Ⅰ The spillway is designed for a flood event of once a year.

3. The multi-stage quantification method for flood control standards of landslide dams based on reservoir capacity as described in claim 1, characterized in that: The recovery and treatment phase Stage Ⅱ The calculation model for the flood control standard of the river channel is shown in equation (3): Equation (3); In the formula: P Ⅱ (V) For the recovery and disposal phase Stage Ⅱ The flood control standard for the river is once a year. P 0 The original flood control standard for the river channel is once a year; max() is the maximum value function.

4. The multi-stage quantification method for flood control standards of landslide dams based on reservoir capacity as described in claim 1, characterized in that: The single phase Stage The flood control standard calculation model is shown in equation (4): Equation (4); In the formula: P(V) Single-stage Stage Flood control standard: once a year; P 0 The original flood control standard for the river channel is once a year.

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