Method for measuring and calculating debris flow control

Abstract

The application provides a method for calculating the flow control of debris flow, comprising the following steps: S1, determining the flow characteristics of the debris flow in the protection area according to the characteristics of the prevention and control project; S2, determining the position and form of the flow control dam and drafting the initial dam height; S3, taking the overflow port height as the starting point to draw the peak regulation reservoir capacity; S4, obtaining the peak flow and flow time after the peak regulation by the difference method according to the peak regulation flow control formula; S5, if the peak flow after the peak regulation is greater than the characteristic flow of the protection project, returning to step S2 to increase the dam height, otherwise, reducing the dam height until the requirements of the engineering design are met. The peak regulation flow curve is obtained by the difference method, the peak flow and flow time after the peak regulation are obtained, the flow control dam is arranged at the end of the drainage project to control the flow, the peak regulation flow control formula is calculated, and after the appropriate flow control peak regulation reservoir capacity is arranged, the good peak reduction effect can be achieved, and the pressure of the drainage and protection is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geological disaster prevention, and in particular to a method for calculating mud flow control. BACKGROUND

[0002] Mud flow is a natural disaster widely distributed in mountainous areas, which breaks out suddenly and moves fast with great impact. A large amount of mud and stones carried by the mud flow can not only bury farmland, forest, village and town in an instant, but also destroy bridge piers, houses, roadbeds, and directly enter rivers and reservoirs to cause dammed lakes or raise riverbeds, causing more secondary disasters, seriously threatening water conservancy and hydropower projects, and causing flood disasters in the downstream, and destroying the ecological environment of the mountainous area. Mud flow disaster has become a prominent problem to be solved in the current disaster prevention and mitigation work, especially the severe challenge of large-scale mud flow disaster risk. By building a mud flow dynamics simulation and engineering control platform, mud flow disaster can be actively and effectively prevented and mitigated.

[0003] The mud flow accumulation sector often houses the most important residential areas of mountain residents. People want to live in the mud flow area, occupy the channel, and affect the mud flow. If the mud flow is greater than the flow capacity of the channel, it will threaten the safety of life and property of residents. Therefore, how to safely and reasonably control the mud flow is the core problem of mountain mud flow drainage and protection. At present, the main engineering measures have an impact on the flow elements of mud flow. The prevention measures for mud flow mainly include solid source, blocking, drainage, and sedimentation. These measures have an impact on the flow of the channel. If there is a peak-shaving reservoir, it will affect the flow control. The blocking of the flow control is the main one. Therefore, the control dam with blocking engineering is often set at the inlet section of the drainage. When we manage the mud flow, drainage engineering is necessary. The drainage facilities include drainage channels and protection dikes. When the mud flow comes, the drainage and protection positions are often relatively flat, which are residential areas and important facility areas. However, the mud flow has the characteristics of sharp and thin, which leads to a large peak flow. The pressure of protection and drainage is large, which sometimes leads to the failure of engineering management. Relocation and other measures must be taken to avoid disasters. If the mud flow can be controlled and the peak can be shaved, the pressure of drainage will be greatly reduced. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for calculating mud flow control. By using the peak-shaving control formula, the control dam is set at the end of the drainage to shave the peak of the mud flow and achieve the purpose of flow control.

[0005] The technical scheme adopted by the present application to solve the technical problem is:

[0006] A method for calculating mud flow control, comprising the following steps:

[0007] S1, determine the flow characteristics of the protection area of the debris flow and the protection project according to the characteristics of the prevention and control project;

[0008] S2, determine the position and form of the flow control dam, and draft the initial dam height;

[0009] S3, take the overflow port height as the starting point to draw the peak regulation reservoir capacity;

[0010] S4, according to the peak regulation flow formula, the peak regulation flow curve is obtained by difference method, and the peak flow after regulation and the flow time are obtained;

[0011] The peak regulation flow formula is as follows:

[0012]

[0013] In formula (I), Δt is the calculation period length, unit: s; Q t is the initial inflow of the reservoir at t period, unit: m 3 / s; Q t+1 is the final inflow of the reservoir at t period, unit: m 3 / s; q t is the initial outflow of the reservoir at t period, unit: m 3 / s; q t+1 is the final outflow of the reservoir at t period, unit: m 3 / s; V t is the initial reservoir storage at t period, unit: m 3 ; V t+1 is the final reservoir storage at t period, unit: m 3 ;

[0014] The formula of the difference method is as follows:

[0015]

[0016] In formula (II), Q c is the peak flow of debris flow, unit: m 3 / s; T is the total flow time of debris flow, unit: s; Q is the flow of debris flow, unit: m 3 / s, t is the calculation time, unit: s;

[0017] S5, if the peak flow after regulation is greater than the characteristic flow of the protection project, return to step S2 to increase the dam height, otherwise reduce the dam height, until the requirements of the engineering design are met.

[0018] The flow control dam overflows at the overflow port of the flow control dam when the debris flow overflows, and the calculation formula of the overflow is as follows:

[0019]

[0020] In formula (three), Q is the peak flow of the debris flow, and the unit is m 3 / s; m is the debris flow flow coefficient; B is the bottom width of the overflow port, and the unit is m; H0 is the water depth passing through the port, and the unit is m.

[0021] In step S1, the flow characteristics of the debris flow include the peak flow of the debris flow and the flow time of the debris flow, the peak flow of the debris flow is 10 m 3 / s, and the flow time of the debris flow is 1800 s.

[0022] In step S1, the engineering characteristics include viscous debris flow and dilute debris flow, and the viscous debris flow and the dilute debris flow both have the characteristics of sharp and thin.

[0023] In step S3, when the overflow port height is 10 m, the peak regulation capacity is 0; when the overflow port height is 12 m, the peak regulation capacity is 10000 m 3 .

[0024] In step S5, the peak flow after peak regulation is 4.4 m 3 / s, which is 44% of the peak flow of the debris flow; and the flow time after peak regulation is 4100 s, which is 2.28 times of the flow time of the debris flow.

[0025] The beneficial effects of the present application are:

[0026] 1. The peak flow after peak regulation is obtained by calculating the peak regulation flow curve, and the flow control dam is arranged at the end of the drainage project to control the flow, and the peak regulation control formula is calculated, and after the appropriate peak regulation control capacity is set, the peak regulation effect is good, the pressure of drainage and protection is reduced, the design of the prevention and control project is safer, more reasonable and feasible, and better economic and social benefits are brought to the project design.

[0027] 2. According to the calculation formula of the overflow at the overflow port, it can be seen that the debris flow exists when flowing, and the flood regulation capacity is formed in the reservoir area, which will reduce the peak flow of the debris flow and reduce the flow pressure of the downstream debris flow, which has important significance for disaster prevention and reduction downstream, and basically a flow control dam is arranged on the upper side when designing the downstream drainage and protection dike, but the influence of flow control and the role of flow control of the upper side retaining dam are not considered in the calculation, and the engineering design will tend to be conservative, especially when the height and width of the built bridge and dike are difficult to implement; the formula is calculated by this way, so as to obtain better results and optimize the scheme and save the cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a typical debris flow curve diagram;

[0029] Figure 2Peak regulation reservoir capacity over flow curve diagram

[0030] Figure 3 Empty reservoir over flow curve diagram

[0031] Figure 4 Peak regulation process curve diagram. DETAILED DESCRIPTION

[0032] The application is further illustrated below in conjunction with the accompanying drawings and examples.

[0033] The flow process of debris flow, whether viscous debris flow or dilute debris flow, has the characteristic of sharp and thin, and the over flow time of debris flow is relatively short compared with flood. From the time sequence of the overall fluid form change and the cause, the simple process is: mountain flood -> debris flow -> mountain flood, which can be repeated, i.e. the array flow of debris flow, but for debris flow gully, the mountain flood in the early and late stages is often small and can be ignored, such as Figure 1 .

[0034] A method for measuring and calculating the control of debris flow, comprising the following steps:

[0035] S1, determining the over flow characteristics of the debris flow in the protection area according to the characteristics of the prevention and control project and the economic and feasible over flow characteristics of the protection project;

[0036] S2, determining the position and form of the control dam (the dam body position should meet the topographic and geological conditions; the dam body form can be a solid dam or a gap dam), and drafting the initial dam height;

[0037] S3, taking the overflow port height as the starting point to draw the peak regulation reservoir capacity;

[0038] S4, obtaining the peak flow and over flow time after peak regulation by solving the peak regulation over flow curve through the difference method according to the peak regulation control formula;

[0039] The peak regulation control formula is as follows:

[0040]

[0041] In formula (I), Δt is the calculation period length, in seconds; Q t is the initial inflow of the reservoir in the t period, in m 3 / s; Q t+1 is the final inflow of the reservoir in the t period, in m 3 / s; q t is the initial outflow of the reservoir in the t period, in m 3 / s; q t+1 is the final outflow of the reservoir in the t period, in m 3 / s; V t is the initial reservoir storage in the t period, in m3 V t+1 The reservoir's water storage at the end of time period t is expressed in cubic meters (m³). 3 ;

[0042] The formula for the difference method is as follows:

[0043]

[0044] In equation (ii), Q c This represents the peak flow rate of the debris flow, in cubic meters per second (m³). 3 / s; T is the total flow time of the debris flow, in seconds; Q is the flow rate of the debris flow, in cubic meters per second. 3 / s, where t is the calculation time in seconds;

[0045] S5. If the peak flow after peak shaving is greater than the characteristic flow of the protection project, return to step S2 to increase the dam height, and vice versa, decrease the dam height until the requirements of the engineering design are met.

[0046] When debris flow occurs, the flow passes through the overflow outlet of the control dam. The calculation formula for the flow is as follows:

[0047]

[0048] In equation (iii), Q represents the peak flow rate of the debris flow, in m³ / s. 3 / s; m is the debris flow coefficient; B is the bottom width of the overflow outlet, in meters; H0 is the water depth at the outlet, in meters.

[0049] The values ​​of the debris flow flow coefficient m are shown in Table 1.

[0050]

[0051] Table 1. Flow coefficient m value

[0052] In step S1, such as Figure 1 As shown, the flow characteristics of the debris flow include the peak flow rate and the flow time, wherein the peak flow rate is 10 m³ / s. 3 / s, the flow time of the debris flow is 1800s.

[0053] In step S1, the engineering characteristics include viscous debris flow and dilute debris flow, both of which are characterized by being sharp and slender.

[0054] In step S3, when the overflow outlet height is 10m, the peak-shaving reservoir capacity is 0; when the overflow outlet height is 12m, the peak-shaving reservoir capacity is 10000m³. 3 .

[0055] like Figure 2As shown, considering the peak-shaving reservoir capacity, peak-shaving overcurrent will reduce the peak flow and extend the overcurrent time, thus achieving the ability to control the flow.

[0056] like Figure 3 As shown, if the control dam is empty before the debris flow occurs, or if there is empty reservoir capacity, there will be no flow in the early stage.

[0057] In step S5, the peak flow rate after peak shaving is 4.4 m³ / s. 3 / s, which is 44% of the peak flow rate of the debris flow; the flow time after peak shaving is 4100s, which is 2.28 times the flow time of the debris flow.

[0058] like Figure 4 As shown, by utilizing the peak-shaving capacity of the flow control dam, the peak flow rate of debris flow is significantly reduced, and the flow time of debris flow is greatly extended. This achieves the goal of exchanging peak flow rate for capacity and time, ensuring the safe passage of debris flow in the drainage facilities.

[0059] The peak flow curve is obtained by using the finite difference method to obtain the peak flow and flow time after peak shaving. A flow control dam is set at the end of the drainage project to control the flow. According to the peak shaving and flow control formula, after setting an appropriate flow control and peak shaving reservoir capacity, it can play a good role in peak reduction, reduce the pressure of drainage and protection, and make the design of the prevention and control project safer, more reasonable and feasible, bringing good economic and social benefits to the project design.

[0060] The calculation formula for the overflow at the spillway shows that debris flows have a stagnant effect, creating flood control capacity in the reservoir area. This reduces the peak flow of debris flows and alleviates the flow pressure downstream, which is of great significance for downstream disaster prevention and mitigation. Currently, the design of downstream drainage and protection dikes basically includes a flow control dam at the upper edge, but the influence of flow control and the flow control function of the upper edge dam are not considered in the calculation. This leads to a conservative engineering design, especially when it is difficult to implement measures to raise and widen existing bridges and dikes. This formula verification method aims to obtain better results, optimize the scheme, and save costs.

[0061] The operational characteristics of debris flows are the most important parameters in the design of debris flow control projects. The design parameters for controlling debris flows through systematic debris flow control projects are also part of the design of debris flow control projects. Debris flow control calculation is the core work of the design. However, the analytical solution of the differential equations involved in debris flow control calculation is difficult, and numerical methods can only be used for calculation. This invention considers different engineering measures and different working conditions for calculation, which is simpler and more convenient.

[0062] The above merely describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calculating debris flow control, characterized in that: Includes the following steps: S1. Determine the flow characteristics and protection projects of debris flow in the protected area based on the characteristics of the prevention and control project; S2. Determine the location and form of the flow control dam, and determine the initial dam height; S3. Draw the peak-shaving storage capacity starting from the overflow outlet height; S4. Based on the peak shaving and flow control formula, the peak shaving flow curve is obtained by the differential method to obtain the peak flow and flow time after peak shaving. The peak-shaving and current control formula is as follows: In equation (1), Δt is the length of the calculation period, in seconds; Q t The initial inflow rate during time period t, in meters. 3 / s;Q t+1 The inbound flow rate at the end of time period t, in meters. 3 / s;q t The initial outflow rate during time period t is expressed in m³. 3 / s;q t+1 The outbound flow rate at the end of time period t, in meters. 3 / s;V t The initial water storage of the reservoir during time period t is expressed in cubic meters (m³). 3 ; V t+1 The reservoir's water storage at the end of time period t is expressed in cubic meters (m³). 3 ; The formula for the difference method is as follows: In equation (ii), Q c This represents the peak flow rate of the debris flow, in cubic meters per second (m³). 3 / s; T is the total flow time of the debris flow, in seconds; Q is the flow rate of the debris flow, in cubic meters per second. 3 / s, where t is the calculation time in seconds; S5. If the peak flow after peak shaving is greater than the characteristic flow of the protection project, return to step S2 to increase the dam height, and vice versa, decrease the dam height until the requirements of the engineering design are met.

2. The method for calculating debris flow control as described in claim 1, characterized in that: When debris flow occurs, the flow passes through the overflow outlet of the control dam. The calculation formula for the flow is as follows: In equation (iii), Q represents the peak flow rate of the debris flow, in m³ / s. 3 / s; m is the debris flow coefficient; B is the bottom width of the overflow outlet, in meters; H0 is the water depth at the outlet, in meters.

3. The method for calculating debris flow control as described in claim 1, characterized in that: In step S1, the flow characteristics of the debris flow include the peak flow rate and the flow time, wherein the peak flow rate is 10 m³ / s. 3 / s, the flow time of the debris flow is 1800s.

4. The method for calculating debris flow control as described in claim 1, characterized in that: In step S1, the engineering characteristics include viscous debris flow and dilute debris flow, both of which are characterized by being sharp and slender.

5. The method for calculating debris flow control as described in claim 1, characterized in that: In step S3, when the overflow outlet height is 10m, the peak-shaving reservoir capacity is 0; when the overflow outlet height is 12m, the peak-shaving reservoir capacity is 10000m³. 3 .

6. The method for calculating debris flow control as described in claim 1, characterized in that: In step S5, the peak flow rate after peak shaving is 4.4 m³ / s. 3 / s, which is 44% of the peak flow rate of the debris flow; the flow time after peak shaving is 4100s, which is 2.28 times the flow time of the debris flow.

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