CN105740620A - Calculation method of debris flow impact force - Google Patents

Abstract

The invention relates to a calculation method of debris flow impact force, and belongs to the field of the debris flow prevention and treatment project and the water conservancy project. The calculation method is as follows: F=0.225([Tau]/rgd1<-0.1>(d/d0)<0.05>(Em<2>V<4>)<1/3>sin<0.5[Theta]>). The method considers a basic theory of dimensional homogeneity for impact force calculation, is suitable for the large-scale practical calculation of the field, and exhibits higher disaster prevention applicability for the disaster prevention and reduction of the debris flow. For all impact force problems, the impact force can be obtained by calculation through parameters including the obtained mass, kinematic velocity, kinematic direction, a plane included angle with an impacted object and elasticity modulus of an impact object, the elasticity modulus of an impacted object and the like without the limitation of materials, so that the calculation method also has an application value for other impact force problems. Accuracy is verified through experiments, and the impact force which may be caused by the impact object can be accurately calculated so as to design a defensive measure according to the impact force.

Description

The computational methods of the impulsive force of mud flow

Technical field

The present invention relates to the computational methods of a kind of impulsive force of mud flow, belong to debris flow control works, hydraulic engineering Field.

Background technology

China is to suffer one of the most serious country of state of debris flow disasters in the world, especially such as Tibet, west area, The ground such as Sichuan, Gansu, Xinjiang, Yunnan, Chongqing.Mud-rock-flow-impact moment can discharge substantial amounts of early stage gradually Accumulation material and huge energy, there is great impact failure power, in mud-rock flow place of arrival, highway, bridge, The means of transportation such as railway are often destroyed by rush of water, become silted up and bury, and being destroyed by rush of water in good farmland, rivers are blocked, be therefore mountain area generally exist and The Disasters Type that destruction is the strongest, the roadbed of serious threat mountain highway, bridge, culvert structure safety.

Due to the complexity of debris flow body material composition, the uncertainty breaking out the time and powerful damage, cause Make progress in terms of the impulsive force of mud flow so far slow.The impulsive force of mud flow is by debris flow slurry dynamic pressure Form with megalith impact force two parts, and causing the principal element of structural deterioration is the impulsive force of boulder.Now Main impulsive force of mud flow computational methods can be generalized as on-the-spot test method, hydrodynamic method, ship impingement method, Mechanics of materials method, pressure wave method and landforms person's movements and expression method.Wherein on-the-spot test method, hydrodynamic method, pressure wave method Being all test debris flow slurry impulsive force and wave impact force with landforms person's movements and expression method, value of calculation is less than normal, it is impossible to be used for Field truth.Ship impingement method, mechanics of materials method and elastic collision method mainly calculate megalith in mud-rock flow Impact force, but in ship impingement method, kinetic energy reduction coefficient, elastic deformation coefficient cannot accurately obtain, the meter made Calculation resultant error is big.Mechanics of materials method is main according to being calculated by cantilever beam and simply supported beam, and usage range is narrow. Therefore a desk research and the calculating impulsive force model that can be suitable in the wild seem extremely important, and this is also mudstone The basis of stream diaster prevention and control engineering design.

Summary of the invention

For in the computational methods of existing mud-rock flow megalith impulsive force, calculating is complicated, dimension is discord and error is big Problem, the invention provides a kind of dimension harmony, the computational methods of the result of calculation impulsive force of mud flow more accurately.

Concrete technical scheme is: the impact force's calculation method of mud-rock flow:

F=0.225 (τ/rgd₁)^(-0.1)(d/d₀)^0.05(Em²V⁴)^1/3sin^0.5θ (1)

In formula:

The F impulsive force of mud flow, N；

τ yield stress, Pa；

R mud-rock flow unit weight, kg/m³；

G acceleration of gravity, g=9.81kg/m²；

d₁Slurry particle diameter, d₁=0.00005m；

D mud-rock flow suspension particle diameter, m；

d₀Minimum coarse granule particle diameter, d in mud-rock flow₀=0.002m；

Megalith quality, kg in m mud-rock flow；

Megalith movement velocity, m/s in V mud-rock flow；

In q mud-rock flow the megalith direction of motion with by the plane included angle of alluvium, unit °；

E synthetical elastic modulus,

E₁Megalith elastic modelling quantity in mud-rock flow, Pa；

E₂By alluvium elastic modelling quantity, Pa in mud-rock flow.

The impact force's calculation method of mud-rock flow that the present invention provides, for impact force's calculation consider dimension harmonious this One ultimate principle, it is adaptable to the Practical Calculation of field large scale, preventing and reducing natural disasters for mud-rock flow, it is higher anti-to have The calamity suitability；For all of impulsive force problem, can by the alluvium quality obtained, movement velocity, The direction of motion with by the plane included angle of alluvium, elastic modelling quantity and by parameters such as the elastic modelling quantity of alluvium, meter Calculation obtains impulsive force, is not limited by material, therefore also has using value for other impulsive force problems；Through real Demonstrate accuracy, can accurately calculate the impulsive force that alluvium is likely to result in, thus according to impulsive force Size design defensive measure.

Detailed description of the invention

It is described in conjunction with the embodiments the detailed description of the invention of the present invention.

Embodiment 1

In July 9 nineteen eighty-two mud-rock flow, megalith blocks Chengdu-Kunming railway profit according to the bridge pier reached in the middle of ditch bridge, According to the inspection of the scene of a crime, estimate respectively and obtain relevant parameter and be: alluvium quality is 414000kg, movement velocity 8.9m/s, the direction of motion with by 90 °, the plane included angle of alluvium, elastic modelling quantity 49 × 10⁹Pa, by alluvium Elastic modelling quantity 26 × 10⁹Pa。

Obtain Li Ziyi reaching gully mud-rock flow by data check is viscous mud-flow, and its unit weight is 2350kg/m³, Its yield stress value is 8000Pa, and suspension particle diameter takes 0.5m, obtains the impulsive force of mud-rock flow according to formula (1) Being 2909 tons, and the anti-disconnected power of data display bridge pier is 1200 tons, the biggest impulsive force destroys greatly Bridge bridge pier is not at all surprising.

Embodiment 2

June nineteen eighty-three, Dongchuan Yunnan reached moral ditch, two steel pipes that in mud-rock flow, stone percussion welding is connected together On, they are bent over not being broken off, and the breaking strength of steel pipe is 2860 tons, according to the inspection of the scene of a crime, estimate respectively Measuring relevant parameter is: alluvium quality is 23060kg, movement velocity 12m/s, the direction of motion with rushed Hit 90 °, the plane included angle of thing, elastic modelling quantity 42 × 10⁹Pa, by the elastic modelling quantity 21 × 10 of alluvium⁹Pa。

Must arrive moral gully mud-rock flow by data is viscous mud-flow, and its unit weight is 2000kg/m³, its surrender should Power value is 8000Pa, and suspension particle diameter takes 0.3m, and the impulsive force obtaining mud-rock flow according to formula (3) is 2647 tons, Less than the breaking strength of steel pipe, the most simply it is bent over not fractureing.

Claims (2)

1. the impact force's calculation method of mud-rock flow, it is characterised in that:

F=0.225 (τ/rgd₁)^(-0.1)(d/d₀)^0.05(Em²V⁴)^1/3sin^0.5θ

In formula:

The F impulsive force of mud flow, N；

τ yield stress, Pa；

R mud-rock flow unit weight, kg/m³；

G acceleration of gravity, g=9.81kg/m²；

d₁Slurry particle diameter, d₁=0.00005m；

D mud-rock flow suspension particle diameter, m；

d₀Minimum coarse granule particle diameter, d in mud-rock flow₀=0.002m；

Megalith quality, kg in m mud-rock flow；

Megalith movement velocity, m/s in V mud-rock flow；

In q mud-rock flow the megalith direction of motion with by the plane included angle of alluvium, unit °；

E synthetical elastic modulus.

The impact force's calculation method of mud-rock flow the most according to claim 1, it is characterised in that: described combines Close elastic modelling quantity, $E=\frac{E_1{E}_2}{E_1+2E_2};$

E₁Megalith elastic modelling quantity in mud-rock flow, Pa；

E₂By alluvium elastic modelling quantity, Pa in mud-rock flow.