Multi-stage stacked blocking prevention method for debris flow

Abstract

The invention discloses a multi-stage stacked blocking prevention method for debris flow. The method comprises the following steps: acquiring debris flow channel topography, channel geological conditions, debris flow main parameters and debris flow disaster threat objects in a debris flow prevention area; determining the grade of a debris flow blocking structure building; the construction position of the single-stage flexible debris flow blocking structure is selected; determining structure parameters of the single-stage flexible debris flow blocking structure; a single-stage flexible debris flow blocking structure is established, and single-stage prevention and treatment work is completed; and a single-stage flexible debris flow blocking structure continues to be established, a multi-stage flexible debris flow blocking structure is obtained, and multi-stage prevention and treatment work is completed. According to the debris flow multi-stage stacking blocking prevention and control method, a flexible debris flow blocking structure is built in a channel area where debris flow frequently occurs, debris flow solids do not need to be cleaned after being silted in the blocking structure, and a new flexible debris flow blocking structure is built on the upstream of the original blocking structure which is silted in the debris flow solids again. And the treatment work of areas with frequent debris flow is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of debris flow prevention and control, and relates to a debris flow multi-stage stacking blocking and prevention method. Background Art

[0002] Debris flow is a type of natural disaster in mountainous areas, characterized by sudden outbreak, short duration, high speed, high energy and strong destructive power. To prevent and control debris flow, a comprehensive debris flow prevention and control system based on "stabilization, interception and drainage" has gradually been formed. Various types of intercepting dams are usually built in the debris flow channel to intercept the solid debris flow. However, debris flow intercepting dams generally have problems such as complex construction, loss of interception capacity after the dam is filled with silt, and difficulty in dredging.

[0003] In summary, the existing technology has the problems of complex debris flow retaining structure, long construction time and difficulty in subsequent dredging. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preventing and controlling debris flow with multi-stage stacking blocking, which solves the problems in the prior art of complex debris flow blocking structure, long construction time and difficulty in subsequent dredging.

[0005] The technical solution adopted by the present invention is a multi-level stacking blocking and prevention method for debris flow, comprising the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. According to the siltation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0006] The present invention is also characterized in that: The main parameters of debris flow include the maximum particle size D of debris flow, the debris flow volume v, the debris flow frequency, the debris flow severity γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits.

[0007] The safety level of debris flow prevention and control projects is determined based on the objects threatened by debris flow disasters and the design specifications of debris flow prevention and control projects; the safety levels of debris flow prevention and control projects include safety level one, safety level two, safety level three, and safety level four.

[0008] The building grade of debris flow retaining structure is determined according to the safety grade of debris flow prevention and control project combined with the safety grade information in the design specification of debris flow prevention and control project and the building grade information in the design specification of rolled earth-rock dam; the correspondence between the safety grade of debris flow prevention and control project and the building grade of debris flow retaining structure is as follows: safety grade one corresponds to level one building, safety grade two corresponds to level two building, safety grade three corresponds to level three building, and safety grade four corresponds to level four building.

[0009] The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier, the inclination angle A of the barrier and the horizontal length L of the barrier. The ratio of the vertical height H of the retaining net to the maximum particle size D of the debris flow is (1.5-2):1.

[0010] The structural parameters of the single-stage flexible debris flow barrier structure, including the inclination angle A of the barrier net and the horizontal length L of the barrier net, are obtained by the following steps: A1. Determine the initial inclination angle A0 of the retaining net based on the internal friction angle ф of the debris flow deposit, the cohesion C of the debris flow deposit and the design experience, and determine the set solid material interception volume V0 based on the debris flow channel topography and channel geological conditions, the construction location of the single-stage flexible debris flow interception structure, the debris flow volume v, the debris flow frequency and the debris flow interception structure building grade; A2. Combined with the construction location of the single-stage flexible debris flow barrier structure, the terrain and geological conditions of the debris flow channel, the vertical height H of the barrier net, the initial inclination angle A0 of the barrier net, and the set solid matter interception volume V0, the theoretical horizontal length L0 of the barrier net and the interception margin design length L1 of the barrier net are obtained; A3. The theoretical horizontal length L0 of the barrier net and the design length L1 of the barrier net’s interception margin are added together to obtain the initial horizontal length L2 of the barrier net. A4. The safety factor of the control working condition accumulation body is calculated according to the rigid body limit equilibrium method. The value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams shall not be less than 0 and not greater than 0.2. The inclination angle A of the retaining net is taken as the initial planned inclination angle A0 of the retaining net, and the horizontal length L of the retaining net is taken as the initial planned horizontal length L2 of the retaining net. If the value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0 or greater than 0.2, adjust the initial planned inclination angle A0 of the retaining net.

[0011] If the value after deducting the safety factor required by the design specification for rolled earth-rock dams from the safety factor of the control working condition accumulation body is less than 0, the safety factor of the control working condition accumulation body does not meet the requirements of the design specification for rolled earth-rock dams, and the initial proposed inclination angle A0 of the retaining net should be reduced; if the value after deducting the safety factor required by the design specification for rolled earth-rock dams from the safety factor of the control working condition accumulation body is greater than 0.2, the design scheme has a large safety margin and a low economy, and the initial proposed inclination angle A0 of the retaining net should be increased.

[0012] The safety factor of the accumulation body under the control condition is calculated according to the calculation and analysis method for dam slope stability in the design specification for rolled earth-rock dams SL274 or the design specification for rolled earth-rock dams NB / T10872, and the safety factor of the accumulation body under normal operating conditions, emergency operating conditions I and emergency operating conditions II is calculated respectively by the rigid body limit equilibrium method; the safety factor of the accumulation body under normal operating conditions is the safety factor of the accumulation body under normal operating conditions, the safety factor of the accumulation body under emergency operating conditions I is the safety factor of the accumulation body under heavy rain conditions, and the safety factor of the accumulation body under emergency operating conditions II is the safety factor of the accumulation body under earthquake conditions.

[0013] S7 specifically means that when the terrain of the debris flow channel and the objects threatened by the debris flow disaster have not changed and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure has reached the set solid interception amount or the distance between the siltation surface in front of the barrier net and the top of the barrier net is 0.5m-1.0m, repeat steps S4-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; if the terrain of the debris flow channel and the objects threatened by the debris flow disaster have changed and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure has reached the set solid interception amount or the distance between the siltation surface in front of the barrier net and the top of the barrier net is 0.5m-1.0m, repeat steps S1-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0014] The beneficial effects of the present invention are as follows: the present invention establishes a flexible debris flow intercepting structure in a channel area where debris flow frequently occurs, and the debris flow solids entrained in the debris flow are intercepted and fixed by the intercepting structure. After the debris flow solids in the intercepting structure are full, there is no need to clean them up. A new flexible debris flow intercepting structure is established again upstream of the original intercepting structure full of debris flow solids, which is beneficial to the management of debris flow frequent areas. The flexible debris flow intercepting structure in the present invention has a simple structure, convenient construction, low construction difficulty, fast construction speed and low cost, and can be quickly constructed to play a role in debris flow management; the intercepting structure of the present invention ensures that the debris flow reaches a self-stabilizing state after silting up, and ensures the safety and reliability of the intercepting measures; the present invention avoids the loss of intercepting ability after the intercepting dam is full of silt, because the silted solids do not need to be cleaned up after the intercepting dam is full, thereby reducing the pressure of debris flow prevention and control, and multiple levels of intercepting measures can be flexibly set according to the on-site conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic flow diagram of the multi-stage stacking blocking and prevention method for debris flow of the present invention; Figure 2 is a schematic diagram of a process of blocking a debris flow by a flexible debris flow blocking structure according to an embodiment of the present invention; Figure 3 It is a structural schematic diagram of a single-stage flexible debris flow blocking unit in an embodiment of the present invention.

[0016] In the figure, 1. retaining net; 2. first fixed extension foundation; 3. second fixed extension foundation; 4. third fixed extension foundation; 5. ground; 6. first supporting mechanism; 7. second supporting mechanism; 8. bottom fixing mechanism; 9. single-stage flexible debris flow retaining structure. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Multi-level cascading debris flow prevention and control methods, such as Figure 1 As shown, the following steps are included: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; The main parameters of debris flow include the maximum particle size D of debris flow, the amount of debris flow v, the frequency of debris flow, the weight of debris flow γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; The safety level of debris flow prevention and control projects is determined based on the debris flow disaster threat objects and the debris flow prevention and control project design specifications; the safety levels of debris flow prevention and control projects include safety level 1, safety level 2, safety level 3, and safety level 4; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; The building grade of debris flow barrier structure is determined according to the safety grade of debris flow prevention project combined with the safety grade information in the design specification of debris flow prevention project and the building grade information in the design specification of rolled earth-rock dam; the corresponding relationship between the safety grade of debris flow prevention project and the building grade of debris flow barrier structure is as follows: safety grade one corresponds to first-level buildings, safety grade two corresponds to second-level buildings, safety grade three corresponds to third-level buildings, and safety grade four corresponds to fourth-level buildings; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier, the inclination angle A of the barrier and the horizontal length L of the barrier. The ratio of the vertical height H of the retaining net to the maximum particle size D of the debris flow is (1.5-2):1; The structural parameters of the single-stage flexible debris flow barrier structure, including the inclination angle A of the barrier net and the horizontal length L of the barrier net, are obtained by the following steps: A1. Determine the initial inclination angle A0 of the retaining net based on the internal friction angle ф of the debris flow deposit, the cohesion C of the debris flow deposit and the design experience, and determine the set solid material interception volume V0 based on the debris flow channel topography and channel geological conditions, the construction location of the single-stage flexible debris flow interception structure, the debris flow volume v, the debris flow frequency and the debris flow interception structure building grade; A2. Combined with the construction location of the single-stage flexible debris flow barrier structure, the terrain and geological conditions of the debris flow channel, the vertical height H of the barrier net, the initial inclination angle A0 of the barrier net, and the set solid matter interception volume V0, the theoretical horizontal length L0 of the barrier net and the interception margin design length L1 of the barrier net are obtained; A3. The theoretical horizontal length L0 of the barrier net and the design length L1 of the barrier net’s interception margin are added together to obtain the initial horizontal length L2 of the barrier net. A4. The safety factor of the control working condition accumulation body is calculated according to the rigid body limit equilibrium method. The value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is not less than 0 and not greater than 0.2. The inclination angle A of the retaining net is taken as the initial planned inclination angle A0 of the retaining net, and the horizontal length L of the retaining net is taken as the initial planned horizontal length L2 of the retaining net. If the value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0 or greater than 0.2, adjust the initial planned inclination angle A0 of the retaining net; If the value of the safety factor of the controlled working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0, the safety factor of the controlled working condition accumulation body does not meet the requirements of the design specification for rolled earth-rock dams, and the initial proposed inclination angle A0 of the retaining net is reduced; if the value of the safety factor of the controlled working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is greater than 0.2, the design scheme has a large safety margin and a low economy, and the initial proposed inclination angle A0 of the retaining net is increased; The safety factor of the accumulation body under the control working condition is calculated according to the calculation and analysis method of dam slope stability in the design specification for rolled earth-rock dams SL274 or the design specification for rolled earth-rock dams NB / T10872, and the safety factor of the accumulation body under normal operating conditions, emergency operating conditions I, and emergency operating conditions II respectively by using the rigid body limit equilibrium method; the safety factor of the accumulation body under normal operating conditions is the safety factor of the accumulation body under normal operating conditions, the safety factor of the accumulation body under emergency operating conditions I is the safety factor of the accumulation body under heavy rain conditions, and the safety factor of the accumulation body under emergency operating conditions II is the safety factor of the accumulation body under earthquake conditions; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the terrain of the debris flow channel and the objects threatened by the debris flow disaster have not changed and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure has reached the set solid barrier amount or the distance between the siltation surface in front of the barrier net and the top of the barrier net is 0.5m-1.0m, repeat steps S4-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; if the terrain of the debris flow channel and the objects threatened by the debris flow disaster have changed and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure has reached the set solid barrier amount or the distance between the siltation surface in front of the barrier net and the top of the barrier net is 0.5m-1.0m, repeat steps S1-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0019] Example 1 This embodiment proposes a multi-level stacking debris flow prevention and control method, including the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the terrain of the debris flow channel and the objects threatened by the debris flow disaster have changed and the distance between the siltation surface in front of the barrier net in the established single-stage flexible debris flow barrier structure and the top of the barrier net is 1.0m, repeat steps S1-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0020] Example 2 This embodiment proposes a multi-level stacking debris flow prevention and control method, including the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; The main parameters of debris flow include the maximum particle size D of debris flow, the amount of debris flow v, the frequency of debris flow, the weight of debris flow γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; The safety level of debris flow prevention and control projects is determined based on the debris flow disaster threat objects and the debris flow prevention and control project design specifications; the safety levels of debris flow prevention and control projects include safety level 1, safety level 2, safety level 3, and safety level 4; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; The building grade of debris flow barrier structure is determined according to the safety grade of debris flow prevention project combined with the safety grade information in the design specification of debris flow prevention project and the building grade information in the design specification of rolled earth-rock dam; the corresponding relationship between the safety grade of debris flow prevention project and the building grade of debris flow barrier structure is as follows: safety grade one corresponds to first-level buildings, safety grade two corresponds to second-level buildings, safety grade three corresponds to third-level buildings, and safety grade four corresponds to fourth-level buildings; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the terrain of the debris flow channel and the objects threatened by the debris flow disaster change and the distance between the siltation surface in front of the barrier net in the established single-stage flexible debris flow barrier structure and the top of the barrier net is 0.5m, repeat steps S1-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0021] Example 3 This embodiment proposes a multi-level stacking debris flow prevention and control method, including the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; The main parameters of debris flow include the maximum particle size D of debris flow, the amount of debris flow v, the frequency of debris flow, the weight of debris flow γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; The safety level of debris flow prevention and control projects is determined based on the debris flow disaster threat objects and the debris flow prevention and control project design specifications; the safety levels of debris flow prevention and control projects include safety level 1, safety level 2, safety level 3, and safety level 4; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; The building grade of debris flow barrier structure is determined according to the safety grade of debris flow prevention project combined with the safety grade information in the design specification of debris flow prevention project and the building grade information in the design specification of rolled earth-rock dam; the corresponding relationship between the safety grade of debris flow prevention project and the building grade of debris flow barrier structure is as follows: safety grade one corresponds to first-level buildings, safety grade two corresponds to second-level buildings, safety grade three corresponds to third-level buildings, and safety grade four corresponds to fourth-level buildings; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier, the inclination angle A of the barrier and the horizontal length L of the barrier. The ratio of the vertical height H of the retaining net to the maximum particle size D of the debris flow is 1.5:1; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the terrain of the debris flow channel and the objects threatened by the debris flow disaster change and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure reaches the set solid barrier amount, repeat steps S1-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0022] Example 4 This embodiment proposes a multi-level stacking debris flow prevention and control method, including the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; The main parameters of debris flow include the maximum particle size D of debris flow, the amount of debris flow v, the frequency of debris flow, the weight of debris flow γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; The safety level of debris flow prevention and control projects is determined based on the debris flow disaster threat objects and the debris flow prevention and control project design specifications; the safety levels of debris flow prevention and control projects include safety level 1, safety level 2, safety level 3, and safety level 4; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; The building grade of debris flow barrier structure is determined according to the safety grade of debris flow prevention project combined with the safety grade information in the design specification of debris flow prevention project and the building grade information in the design specification of rolled earth-rock dam; the corresponding relationship between the safety grade of debris flow prevention project and the building grade of debris flow barrier structure is as follows: safety grade one corresponds to first-level buildings, safety grade two corresponds to second-level buildings, safety grade three corresponds to third-level buildings, and safety grade four corresponds to fourth-level buildings; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier, the inclination angle A of the barrier and the horizontal length L of the barrier. The ratio of the vertical height H of the barrier net to the maximum particle size D of the debris flow is 1.75:1; The structural parameters of the single-stage flexible debris flow barrier structure, including the inclination angle A of the barrier net and the horizontal length L of the barrier net, are obtained by the following steps: A1. Determine the initial inclination angle A0 of the retaining net based on the internal friction angle ф of the debris flow deposit, the cohesion C of the debris flow deposit and the design experience, and determine the set solid material interception volume V0 based on the debris flow channel topography and channel geological conditions, the construction location of the single-stage flexible debris flow interception structure, the debris flow volume v, the debris flow frequency and the debris flow interception structure building grade; A2. Combined with the construction location of the single-stage flexible debris flow barrier structure, the terrain and geological conditions of the debris flow channel, the vertical height H of the barrier net, the initial inclination angle A0 of the barrier net, and the set solid matter interception volume V0, the theoretical horizontal length L0 of the barrier net and the interception margin design length L1 of the barrier net are obtained; A3. The theoretical horizontal length L0 of the barrier net and the design length L1 of the barrier net’s interception margin are added together to obtain the initial horizontal length L2 of the barrier net. A4. The safety factor of the control working condition accumulation body is calculated according to the rigid body limit equilibrium method. The value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification of rolled earth-rock dam is not less than 0 and not more than 0.2. The inclination angle A of the retaining net is taken as the initial inclination angle A0 of the retaining net, and the horizontal length L of the retaining net is taken as the initial horizontal length L2 of the retaining net; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the terrain of the debris flow channel and the objects threatened by the debris flow disaster have not changed and the distance between the siltation surface in front of the barrier net and the top of the barrier net in the established single-stage flexible debris flow barrier structure is 1.0m, repeat steps S4-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0023] Example 5 This embodiment proposes a multi-level stacking debris flow prevention and control method, including the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; The main parameters of debris flow include the maximum particle size D of debris flow, the amount of debris flow v, the frequency of debris flow, the weight of debris flow γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; The safety level of debris flow prevention and control projects is determined based on the debris flow disaster threat objects and the debris flow prevention and control project design specifications; the safety levels of debris flow prevention and control projects include safety level 1, safety level 2, safety level 3, and safety level 4; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; The building grade of debris flow barrier structure is determined according to the safety grade of debris flow prevention project combined with the safety grade information in the design specification of debris flow prevention project and the building grade information in the design specification of rolled earth-rock dam; the corresponding relationship between the safety grade of debris flow prevention project and the building grade of debris flow barrier structure is as follows: safety grade one corresponds to first-level buildings, safety grade two corresponds to second-level buildings, safety grade three corresponds to third-level buildings, and safety grade four corresponds to fourth-level buildings; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier, the inclination angle A of the barrier and the horizontal length L of the barrier. The ratio of the vertical height H of the retaining net to the maximum particle size D of the debris flow is 1.5:1; The structural parameters of the single-stage flexible debris flow barrier structure, including the inclination angle A of the barrier net and the horizontal length L of the barrier net, are obtained by the following steps: A1. Determine the initial inclination angle A0 of the retaining net based on the internal friction angle ф of the debris flow deposit, the cohesion C of the debris flow deposit and the design experience, and determine the set solid material interception volume V0 based on the debris flow channel topography and channel geological conditions, the construction location of the single-stage flexible debris flow interception structure, the debris flow volume v, the debris flow frequency and the debris flow interception structure building grade; A2. Combined with the construction location of the single-stage flexible debris flow barrier structure, the terrain and geological conditions of the debris flow channel, the vertical height H of the barrier net, the initial inclination angle A0 of the barrier net, and the set solid matter interception volume V0, the theoretical horizontal length L0 of the barrier net and the interception margin design length L1 of the barrier net are obtained; A3. The theoretical horizontal length L0 of the barrier net and the design length L1 of the barrier net’s interception margin are added together to obtain the initial horizontal length L2 of the barrier net. A4. The safety factor of the control working condition accumulation body is calculated according to the rigid body limit equilibrium method. The value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is not less than 0 and not greater than 0.2. The inclination angle A of the retaining net is taken as the initial planned inclination angle A0 of the retaining net, and the horizontal length L of the retaining net is taken as the initial planned horizontal length L2 of the retaining net. If the value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0 or greater than 0.2, adjust the initial planned inclination angle A0 of the retaining net; If the value of the safety factor of the controlled working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0, the safety factor of the controlled working condition accumulation body does not meet the requirements of the design specification for rolled earth-rock dams, and the initial proposed inclination angle A0 of the retaining net is reduced; if the value of the safety factor of the controlled working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is greater than 0.2, the design scheme has a large safety margin and a low economy, and the initial proposed inclination angle A0 of the retaining net is increased; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the terrain of the debris flow channel and the objects threatened by the debris flow disaster have not changed and the distance between the siltation surface in front of the barrier net in the established single-stage flexible debris flow barrier structure and the top of the barrier net is 0.5m, repeat steps S4-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0024] Example 6 This embodiment proposes a multi-level stacking debris flow prevention and control method, including the following steps: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; The main parameters of debris flow include the maximum particle size D of debris flow, the amount of debris flow v, the frequency of debris flow, the weight of debris flow γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; The safety level of debris flow prevention and control projects is determined based on the debris flow disaster threat objects and the debris flow prevention and control project design specifications; the safety levels of debris flow prevention and control projects include safety level 1, safety level 2, safety level 3, and safety level 4; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; The building grade of debris flow barrier structure is determined according to the safety grade of debris flow prevention project combined with the safety grade information in the design specification of debris flow prevention project and the building grade information in the design specification of rolled earth-rock dam; the corresponding relationship between the safety grade of debris flow prevention project and the building grade of debris flow barrier structure is as follows: safety grade one corresponds to first-level buildings, safety grade two corresponds to second-level buildings, safety grade three corresponds to third-level buildings, and safety grade four corresponds to fourth-level buildings; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier, the inclination angle A of the barrier and the horizontal length L of the barrier. The ratio of the vertical height H of the retaining net to the maximum particle size D of the debris flow is 2:1; The structural parameters of the single-stage flexible debris flow barrier structure, including the inclination angle A of the barrier net and the horizontal length L of the barrier net, are obtained by the following steps: A1. Determine the initial inclination angle A0 of the retaining net based on the internal friction angle ф of the debris flow deposit, the cohesion C of the debris flow deposit and the design experience, and determine the set solid material interception volume V0 based on the debris flow channel topography and channel geological conditions, the construction location of the single-stage flexible debris flow interception structure, the debris flow volume v, the debris flow frequency and the debris flow interception structure building grade; A2. Combined with the construction location of the single-stage flexible debris flow barrier structure, the terrain and geological conditions of the debris flow channel, the vertical height H of the barrier net, the initial inclination angle A0 of the barrier net, and the set solid matter interception volume V0, the theoretical horizontal length L0 of the barrier net and the interception margin design length L1 of the barrier net are obtained; A3. The theoretical horizontal length L0 of the barrier net and the design length L1 of the barrier net’s interception margin are added together to obtain the initial horizontal length L2 of the barrier net. A4. The safety factor of the control working condition accumulation body is calculated according to the rigid body limit equilibrium method. The value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is not less than 0 and not greater than 0.2. The inclination angle A of the retaining net is taken as the initial planned inclination angle A0 of the retaining net, and the horizontal length L of the retaining net is taken as the initial planned horizontal length L2 of the retaining net. If the value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0 or greater than 0.2, adjust the initial planned inclination angle A0 of the retaining net; If the value of the safety factor of the controlled working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0, the safety factor of the controlled working condition accumulation body does not meet the requirements of the design specification for rolled earth-rock dams, and the initial proposed inclination angle A0 of the retaining net is reduced; if the value of the safety factor of the controlled working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is greater than 0.2, the design scheme has a large safety margin and a low economy, and the initial proposed inclination angle A0 of the retaining net is increased; The safety factor of the accumulation body under the control working condition is calculated according to the calculation and analysis method of dam slope stability in the design specification for rolled earth-rock dams SL274 or the design specification for rolled earth-rock dams NB / T10872, and the safety factor of the accumulation body under normal operating conditions, emergency operating conditions I, and emergency operating conditions II respectively by using the rigid body limit equilibrium method; the safety factor of the accumulation body under normal operating conditions is the safety factor of the accumulation body under normal operating conditions, the safety factor of the accumulation body under emergency operating conditions I is the safety factor of the accumulation body under heavy rain conditions, and the safety factor of the accumulation body under emergency operating conditions II is the safety factor of the accumulation body under earthquake conditions; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. Based on the sedimentation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; When the debris flow channel terrain and the debris flow disaster threat objects have not changed and the solid accumulation amount in the established single-stage flexible debris flow barrier structure has reached the set solid barrier amount, repeat steps S4-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

[0025] The multi-stage flexible debris flow blocking structure in the embodiment of the present invention is as follows: Figure 2 As shown, it includes three single-stage flexible debris flow blocking structures 9 arranged in sequence along the debris flow flow direction, such as Figure 3As shown, the single-stage flexible debris flow blocking structure 9 includes a second fixed extension foundation 3, which is embedded in the ground 5, and a first fixed extension foundation 2 and a third fixed extension foundation 4 embedded in the ground 5 are respectively arranged on both sides of the second fixed extension foundation 3, a first supporting mechanism 6 is fixedly connected to the first fixed extension foundation 2, a second supporting mechanism 7 is fixedly connected to the second fixed extension foundation 3, a bottom fixing mechanism 8 is fixedly connected to the third fixed extension foundation 4, one end of a blocking net 1 is fixedly connected to the bottom fixing mechanism 8, and the other end of the blocking net 1 is fixedly connected to the first supporting mechanism 6.

[0026] The second supporting mechanism 7 is located between the first supporting mechanism 6 and the bottom fixing mechanism 8, and the second supporting mechanism 7 is fixedly connected to the barrier net 1; the absolute elevation of the first fixed extension foundation 2 is greater than the absolute elevation of the second fixed extension foundation 3, and the absolute elevation of the second fixed extension foundation 3 is greater than the absolute elevation of the third fixed extension foundation 4; one end of the bottom fixing mechanism 8 is fixedly embedded in the third fixed extension foundation 4, and the other end is fixedly connected to one end of the barrier net 1; The difference in absolute elevation between one end of the retaining net 1 on which the bottom fixing mechanism 8 is fixed and the outer wall of one side of the third fixed extension foundation 4 on which the bottom fixing mechanism 8 is provided is the vertical height H of the retaining net; the angle between the retaining net 1 and the horizontal plane is the inclination angle A of the retaining net; the projection length of the retaining net 1 on the horizontal plane is the horizontal length L of the retaining net.

[0027] The present invention uses the barrier net 1 to intercept the debris flow solids entrained in the debris flow and discharge water to the downstream. The debris flow solid accumulation itself is stabilized by adjusting the inclination angle of the barrier net. The setting of the solid accumulation amount retains a large safety margin, thereby ensuring the safety and reliability of the interception measures. If the solid accumulation amount in the single-stage flexible debris flow interception structure reaches the set solid accumulation amount, a single-stage flexible debris flow interception structure can be rebuilt upstream of the original single-stage flexible debris flow interception structure to form a multi-stage interception structure. The single-stage flexible debris flow interception structure has the advantages of simple structure, flexible layout, and avoidance of dredging. The single-stage flexible debris flow interception structure in the present invention can be adjusted according to actual needs to adapt to the on-site environment.

[0028] If the vertical height of the retaining net in the present invention is too small, the lower part of the retaining net will be suspended, and if it is too large, it will affect the stability of the debris flow deposits themselves. Therefore, it is necessary to determine its value with reference to the particle size of the debris flow solid matter; appropriately setting the inclination angle of the retaining net can ensure that after the debris flow occurs, under the protective effect of the retaining net 1, the silt in the retaining net 1 is in a stable state; the flexible single-stage debris flow retaining structure should be built in a location with relatively flat terrain and good bedrock conditions.

[0029] The barrier net 1 is mainly used to intercept solid matter in the debris flow and discharge water to the downstream; the first support mechanism 6 and the second support mechanism 7 are rigid support structures, which mainly play the role of fixing the barrier net 1, and their strength can withstand the weight of the barrier net 1 itself and the impact of the debris flow; Figure 2 As shown, if the amount of solid accumulation in a single-stage flexible debris flow barrier structure reaches the set solid interception amount, a single-stage flexible debris flow barrier structure can be set again upstream, thereby forming a multi-stage flexible debris flow barrier structure as a whole. The single-stage flexible debris flow barrier structure at each level intercepts the upstream debris flow through the barrier net 1, and the solid matter in the net forms a self-stabilizing state after the water in the debris flow is discharged to the downstream. When the debris flow comes, the barrier structure mainly plays a role in blocking the debris flow; after the debris flow occurs, the barrier net only plays a role of safety reserve, and the accumulation in the net can reach a self-stabilizing state.

Claims

1. A multi-level cascading debris flow prevention and control method, characterized in that: The following steps are involved: S1. Obtain the debris flow channel topography, channel geological conditions, main debris flow parameters, and debris flow disaster threat objects in the debris flow prevention and control area; S2. Determine the safety level of debris flow prevention and control projects based on the objects threatened by debris flow disasters; S3. Determine the grade of debris flow blocking structure buildings based on the safety grade of debris flow prevention and control projects; S4. Determine the construction location of the single-stage flexible debris flow barrier structure based on the debris flow channel topography and channel geological conditions; S5. Determine the structural parameters of the single-stage flexible debris flow retaining structure in combination with the main parameters of the debris flow and the construction location of the single-stage flexible debris flow retaining structure; S6. A single-stage flexible debris flow barrier structure is established based on the structural parameters and construction location of the single-stage flexible debris flow barrier structure, and the single-stage prevention and control work is completed; S7. According to the siltation situation in the single-stage flexible debris flow barrier structure, a single-stage flexible debris flow barrier structure is further established upstream thereof to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

2. The method for preventing and controlling debris flow by multi-level stacking according to claim 1 is characterized in that: The main parameters of debris flow include the maximum particle size D of debris flow, the debris flow volume v, the debris flow frequency, the debris flow severity γ, the internal friction angle ф of debris flow deposits, and the cohesion C of debris flow deposits.

3. The method for preventing and controlling debris flow by multi-level stacking according to claim 2 is characterized in that: The safety level of the debris flow prevention and control project is determined based on the objects threatened by the debris flow disaster and the design specifications of the debris flow prevention and control project; the safety levels of the debris flow prevention and control project include safety level one, safety level two, safety level three, and safety level four.

4. The method for preventing and controlling debris flow by multi-level stacking blocking according to claim 3 is characterized in that: The building grade of the debris flow retaining structure is determined based on the safety grade of the debris flow prevention and control project combined with the safety grade information in the debris flow prevention and control project design specifications and the building grade information in the rolled earth-rock dam design specifications; the correspondence between the safety grade of the debris flow prevention and control project and the building grade of the debris flow retaining structure is as follows: safety grade one corresponds to level one buildings, safety grade two corresponds to level two buildings, safety grade three corresponds to level three buildings, and safety grade four corresponds to level four buildings.

5. The method for preventing and controlling debris flow by multi-level stacking blocking according to claim 4 is characterized in that: The structural parameters of the single-stage flexible debris flow barrier structure include the vertical height H of the barrier net, the inclination angle A of the barrier net and the horizontal length L of the barrier net; The ratio of the vertical height H of the retaining net to the maximum particle size D of the debris flow is (1.5-2):

1.

6. The method for preventing and controlling debris flow by multi-level stacking blocking according to claim 5 is characterized in that: The inclination angle A of the barrier net and the horizontal length L of the barrier net in the structural parameters of the single-stage flexible debris flow barrier structure are obtained by the following steps: A1. Determine the initial inclination angle A0 of the retaining net based on the internal friction angle ф of the debris flow deposit, the cohesion C of the debris flow deposit and the design experience, and determine the set solid material interception volume V0 based on the debris flow channel topography and channel geological conditions, the construction location of the single-stage flexible debris flow interception structure, the debris flow volume v, the debris flow frequency and the debris flow interception structure building grade; A2. Combined with the construction location of the single-stage flexible debris flow barrier structure, the terrain and geological conditions of the debris flow channel, the vertical height H of the barrier net, the initial inclination angle A0 of the barrier net, and the set solid matter interception volume V0, the theoretical horizontal length L0 of the barrier net and the interception margin design length L1 of the barrier net are obtained; A3. The theoretical horizontal length L0 of the barrier net and the design length L1 of the barrier net’s interception margin are added together to obtain the initial horizontal length L2 of the barrier net. A4. The safety factor of the control working condition accumulation body is calculated according to the rigid body limit equilibrium method. The value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams shall not be less than 0 and not greater than 0.

2. The inclination angle A of the retaining net is taken as the initial planned inclination angle A0 of the retaining net, and the horizontal length L of the retaining net is taken as the initial planned horizontal length L2 of the retaining net. If the value of the safety factor of the control working condition accumulation body minus the safety factor required by the design specification for rolled earth-rock dams is less than 0 or greater than 0.2, adjust the initial planned inclination angle A0 of the retaining net.

7. The method for preventing and controlling debris flow by multi-level stacking blocking according to claim 6 is characterized in that: If the value obtained by deducting the safety factor required by the design specifications for rolled earth-rock dams from the safety factor of the control condition accumulation body is less than 0, then the safety factor of the control condition accumulation body does not meet the requirements of the design specifications for rolled earth-rock dams, and the initial planned inclination angle A0 of the retaining net should be reduced; if the value obtained by deducting the safety factor required by the design specifications for rolled earth-rock dams from the safety factor of the control condition accumulation body is greater than 0.2, then the design scheme has a large safety margin but a low economy, and the initial planned inclination angle A0 of the retaining net should be increased.

8. The method for preventing and controlling debris flow by multi-level stacking blocking according to claim 7 is characterized in that: The safety factor of the accumulation body under the control working condition is calculated according to the calculation and analysis method of dam slope stability in the design specification for rolled earth-rock dams SL274 or the design specification for rolled earth-rock dams NB / T10872, and the safety factor of the accumulation body under normal operating conditions, emergency operating conditions I, and emergency operating conditions II is calculated using the rigid body limit equilibrium method; The safety factor of the accumulation body under the normal operating condition is the safety factor of the accumulation body under the normal operating condition, the safety factor of the accumulation body under the emergency operating condition I is the safety factor of the accumulation body under the rainstorm condition, and the safety factor of the accumulation body under the emergency operating condition II is the safety factor of the accumulation body under the earthquake condition.

9. The method for preventing and controlling debris flow by multi-level stacking blocking according to any one of claims 1 to 8, characterized in that: The S7 specifically means that when the terrain of the debris flow channel and the debris flow disaster threat object have not changed and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure reaches the set solid interception amount or the distance between the siltation surface in front of the barrier net and the top of the barrier net is 0.5m-1.0m, repeat steps S4-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed; if the terrain of the debris flow channel and the debris flow disaster threat object have changed and the amount of solid accumulation in the established single-stage flexible debris flow barrier structure reaches the set solid interception amount or the distance between the siltation surface in front of the barrier net and the top of the barrier net is 0.5m-1.0m, repeat steps S1-S6 to continue to establish a single-stage flexible debris flow barrier structure upstream of the established single-stage flexible debris flow barrier structure to obtain a multi-stage flexible debris flow barrier structure, and the multi-stage prevention and control work is completed.

Images