CN105404746A - Reliability design method for long and steep downhill highway - Google Patents

Abstract

The present invention discloses a reliability design method for a long and steep downhill highway. The method comprises: 1) constructing a brake hub temperature rise function formula; 2) establishing a reliability expression of braking safety for a truck in a downhill process; 3) calculating longitudinal slope reliability by using an Monte Carlo method, and based on a reliability design method, calculating a safe maximal slope length and a limit safe maximal slope length; and 4) substituting formula (2), formula (3) and formula (4) into formula (1), using a probability that a temperature is less than a safe temperature T2 to complete a design of a different average slope of a longitudinal slope and a corresponding slope length. According to the reliability design method for a long and steep downhill highway; rationality of current highway route design specifications can be analyzed,diversity and discreteness of actual highway operation state parameters are taken into account; and a certainty idea of a current highway longitudinal slope design is broken through, so that the traffic safety of a long and steep downhill road of a highway in China is improved at the design stage, and a transformation from a current certainty idea to a reliability idea of a highway alignment design method in China is promoted.

Description

A kind of reliability design approach of long slope sections

Technical field

The invention belongs to Communication and Transportation Engineering field, be specifically related to a kind of reliability design approach of long slope sections.

Background technology

Reliability design approach, from being born so far, develops very rapid.Always there are some faults in World War II U.S. electronic equipment in transport or storage weapon process, have impact on its fighting capacity, in order to solve the fault that electronic equipment occurs, the U.S. expands organized reliability consideration, and this makes reliability engineering come into the sight line of people gradually.The sixties in 20th century appropriate authority and tissue set up reliability consideration center, reliability basic theory, method of work are deepened, develop the more effective test method of accelerated life test, rapid screening assay these two kinds, open up this new disciplines of reliability being intended to study failure mechanism, establish more effective data system, offer reliability education course.Along with reliability engineering develops rapidly comprehensively, the field of its application is more and more extensive.Progressively apply to mechanical engineering, soft project, Communication and Transportation Engineering, construction work, pharmaceutical engineering, aeronautical engineering, petroleum engineering, management engineering etc. by original electronic engineering at present.

Although reliability engineering obtains at present and uses widely, road route design is seldom used.Along with China's rapid development of economy, mileage open to traffic and automobile pollution increase year by year, traffic hazard thereupon also gets more and more, according to correlation study, China has been one of country that road traffic accident situation is the most serious in the world, annual traffic hazard number and the number of casualties all occupy first place in the world, in different kinds of roads, the pernicious traffic hazard in long slope sections section comparatively takes place frequently always and concentrates, account for the larger specific gravity of the pernicious traffic hazard sum of China, the immediate cause that long downslope traffic hazard takes place frequently mainly length of grade and suddenly cause vehicle overspeed seriously, lorry is frequently braked, cause freight car braking actuator temperature too high, brake function lost efficacy, this present situation underlying causes is behind a lot, China's Current Highway highway route design specification unreasonable is wherein major reason, this unreasonable Longitudinal Slope Design method be mainly reflected in based on the deterministic design thought.

In order to improve the traffic safety level of long and steep downgrade, for this problem, propose the long slope sections reliability design approach based on freight car braking safety, using the critical safety temperature of wagon brake brake efficiency decline as constraint condition, set up the power function of lorry descending process actuators Temperature Rise Model, derivation longitudinal gradient model of reliability calculation, propose the method for solving of longitudinal gradient model of reliability calculation, analyzed by Engineering Projects, the application of demonstration longitudinal gradient reliability design approach, and verify the rationality of reliability design approach.Utilize longitudinal gradient reliability design approach, the rationality of current highway highway route design specification is analyzed, find that the active route design specifications Maximal slope length to the longitudinal gradient of highway and Class I highway lacks regulation.

Finally, based on reliability design approach, by Generally Recognized as safe and limiting safe two security arrangements, calculate the Generally Recognized as safe Maximal slope length corresponding to different average gradient values and the limiting safe Maximal slope length of highway composite grade respectively.

Summary of the invention

Multiple and the chronicity of traffic hazard for long and steep downgrade, the invention provides a kind of reliability design approach of long slope sections.The method considers diversity and the discreteness of highway actual motion state parameter, break through the determinacy thought of current highway Longitudinal Slope Design, improve the traffic safety level of highway in China long downslope from design level, promote highway in China Alignment Design method and make the transition from current the deterministic design thought to reliability design thought.

Realizing above-mentioned purpose technical scheme is:

A reliability design approach for long slope sections, comprises the steps:

1) the brake hub temperature rise functional relation about the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperature is built;

2) reliability model of lorry descending process brake safe is set up;

3) fiduciary level of covering tower calot's method calculating longitudinal gradient Truck brake safe is utilized, based on reliability design approach, by Generally Recognized as safe and limiting safe two security arrangements, calculate the Generally Recognized as safe Maximal slope length corresponding to different average gradient values and the limiting safe Maximal slope length of highway composite grade respectively;

4) by step 1) in formula (2), formula (3), formula (4) formula substitute into step 1) in formula (1) in, by step 3) in, temperature is less than brake safe temperature T _sprobability, evaluate the security of Longitudinal Slope Design, utilize the target reliability degree of brake safe, inverse goes out length of grade corresponding to different mean inclinations, completes the design of the different mean inclination of longitudinal gradient and the length of grade of correspondence.

Step 1) in, constructed brake hub temperature rise functional relation based on indoor and field test, this relational expression comprises the parameters (see formula 1) such as the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperature.Wherein, the initial temperature of brake hub and environment temperature are all obtained by pilot survey data; Assuming that lorry gross weight Normal Distribution, expect it is calculate (see formula 4) at MATLAB platform invoke function command according to pilot survey data with variance; Based on the achievement in research of domestic scholars, the speed that lorry travels at long and steep downgrade meets normal distribution, expects all there is certain relation (see formula 2,3) with standard deviation.

T＝T(v,G,i,L,T ₀,T _a)(1)

Lorry is in the relational expression of long and steep downgrade average velocity about the gradient, and velocity standard difference about the relational expression of average velocity is

$\begin{array}{cc}{\mathrm{\μ}}_v=\stackrel{\‾}{v}=\stackrel{\‾}{v}\left(i\right)& {\mathrm{\σ}}_v={\mathrm{k\μ}}_v\end{array}---\left(2\right)$

According to about research lorry is in the travel speed Normal Distribution of long and steep downgrade, namely

V～N(μ _V,σ _V)(3)

Its Normal Distribution of the actual load-carrying hypothesis of lorry, namely

G～N(μ _G,σ _G)(4)

In formula: T-brake temperature (DEG C); T ()-funtcional relationship; average speed (the kmh of-lorry ^-1); Travel speed (the kmh of V-lorry ^-1); The gross weight (N) of G-lorry; I-mean inclination (%); L-length of grade (km) T ₀the initial temperature (DEG C) of-detent; T _a-environment temperature (DEG C); N ()-normal distribution; μ _vaverage speed (the kmh of-lorry ^-1); σ _vstandard deviation (the kmh of-lorry the speed of a motor vehicle ^-1); μ _gthe mean value (N) of-lorry gross weight; σ _gthe standard deviation (N) of-lorry gross weight;

Step 2) in, using the critical safety temperature of wagon brake brake efficiency decline as constraint condition, set up the reliability expression of lorry descending process brake safe:

P＝P(T≤T _s)＝P(Z≤0)(5)

In formula: Z=T-T _s; T _sthe critical safety temperature (DEG C) that-brake usefulness declines; The fiduciary level of P ()-freight car braking safety, also namely lorry brake hub temperature of lorry in long downslope driving process is less than or equal to T _sprobability.

In step (3), utilize and cover the fiduciary level that tower calot's method calculates freight car braking safety.The random number of each stochastic variable of obeying known distribution is produced by programming, and substituted in power function Z, in sample N, find the number M of content with funtion function Z≤0, as N → ∞, try to achieve brake safe fiduciary level according to Bernoulli law of great numbers, expression formula is:

$P=\underset{N\→\mathrm{\∞}}{\lim }\frac{M}{N}---\left(6\right)$

In formula: P is the fiduciary level of freight car braking safety, M is the number of times of content with funtion function Z≤0, and N is sample number.

Beneficial effect

The invention provides a kind of reliability design approach of long slope sections, consider diversity and the discreteness of highway actual motion state parameter, break through the determinacy thought of current highway Longitudinal Slope Design, improve the traffic safety level of highway in China long downslope from design level, promote highway in China Alignment Design method and make the transition from current the deterministic design thought to reliability design thought.

Accompanying drawing explanation

Fig. 1 is method for designing process flow diagram of the present invention.

Energy conversion schematic diagram when Fig. 2 is lorry descending of the present invention.

Fig. 3 is reliability calculating program flow diagram of the present invention.

Fig. 4 is the gross combination weight distribution plan of embodiment 2.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further elaborated, but be not limitation of the invention,

Embodiment

1) the brake hub temperature rise functional relation about the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperature is built;

2) reliability model of lorry descending process brake safe is set up;

3) fiduciary level of covering tower calot's method calculating longitudinal gradient Truck brake safe is utilized, based on reliability design approach, by Generally Recognized as safe and limiting safe two security arrangements, calculate the Generally Recognized as safe Maximal slope length corresponding to different average gradient values and the limiting safe Maximal slope length of highway composite grade respectively;

4) by step 1) in formula (2), formula (3), formula (4) formula substitute into step 1) in formula (1) in, by step 3) in, temperature is less than brake safe temperature T _sprobability, evaluate the security of Longitudinal Slope Design, utilize the target reliability degree of brake safe, inverse goes out length of grade corresponding to different mean inclinations, completes the design of the different mean inclination of longitudinal gradient and the length of grade of correspondence.

Step 1) in, constructed brake hub temperature rise functional relation based on indoor and field test, this relational expression comprises the parameters (see formula 1) such as the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperature.Wherein, the initial temperature of brake hub and environment temperature are all obtained by pilot survey data; Assuming that lorry gross weight Normal Distribution, expect it is calculate (see formula 4) at MATLAB platform invoke function command according to pilot survey data with variance; Based on the achievement in research of domestic scholars, the speed that lorry travels at long and steep downgrade meets normal distribution, expects all there is certain relation (see formula 2,3) with standard deviation.

T＝T(v,G,i,L,T ₀,T _a)(1)

Lorry is in the relational expression of long and steep downgrade average velocity about the gradient, and velocity standard difference about the relational expression of average velocity is

$\begin{array}{cc}{\mathrm{\μ}}_v=\stackrel{\‾}{v}=\stackrel{\‾}{v}\left(i\right)& {\mathrm{\σ}}_v={\mathrm{k\μ}}_v\end{array}---\left(2\right)$

According to about research lorry is in the travel speed Normal Distribution of long and steep downgrade, namely

V～N(μ _V,σ _V)(3)

Its Normal Distribution of the actual load-carrying hypothesis of lorry, namely

G～N(μ _G,σ _G)(4)

In formula: T-brake temperature (DEG C); T ()-funtcional relationship; average speed (the kmh of-lorry ^-1); Travel speed (the kmh of V-lorry ^-1); The gross weight (N) of G-lorry; I-mean inclination (%); L-length of grade (km) T ₀the initial temperature (DEG C) of-detent; T _a-environment temperature (DEG C); N ()-normal distribution; μ _vaverage speed (the kmh of-lorry ^-1); σ _vstandard deviation (the kmh of-lorry the speed of a motor vehicle ^-1); μ _gthe mean value (N) of-lorry gross weight; σ _gthe standard deviation (N) of-lorry gross weight;

Step 2) in, using the critical safety temperature of wagon brake brake efficiency decline as constraint condition, set up the reliability expression of lorry descending process brake safe:

P＝P(T≤T _s)＝P(Z≤0)(5)

In formula: Z=T-T _s; T _sthe critical safety temperature (DEG C) that-brake usefulness declines; The fiduciary level of P ()-freight car braking safety, also namely lorry brake hub temperature of lorry in long downslope driving process is less than or equal to T _sprobability.

In step (3), utilize and cover the fiduciary level that tower calot's method calculates freight car braking safety.The random number of each stochastic variable of obeying known distribution is produced by programming, and substituted in power function Z, in sample N, find the number M of content with funtion function Z≤0, as N → ∞, try to achieve brake safe fiduciary level according to Bernoulli law of great numbers, expression formula is:

$P=\underset{N\→\mathrm{\∞}}{\lim }\frac{M}{N}---\left(6\right)$

In formula: P is the fiduciary level of freight car braking safety, M is the number of times of content with funtion function Z≤0, and N is sample number.

Embodiment 1

Be illustrated in figure 1 the reliability design approach process flow diagram of the long slope sections based on freight car braking safety of present pre-ferred embodiments:

S101: build brake hub temperature rise functional relation.According to lorry in lower long downslope driving process, driver, in order to regulation speed, frequently uses detent, and this can cause brake hub temperature to raise.A brake hub temperature rise functional relation about factors such as the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperatures is built according to this process;

S102: the reliability model building brake safe.Grow up that slope lorry gross weight specifically distributes, speed specifically distributes and the functional relation of step (1) according to a certain, set up long slope sections brake safe reliability model; Lorry is in long downslope driving process, if without driving force effect, lorry is in without oil inflame state, namely lorry is in and becomes the stage of other energy such as kinetic energy (braking oil consumption is ignored) without chemical energy, so the descending potential energy of this stage mainly lorry itself is kinetic energy and other forms of energy.Theoretical based on desired speed, driver initially can initiatively accelerate at lorry descending, and after speed reaches expectation, lorry also just keeps a certain speeds.Pretend the hypothesis of at the uniform velocity descending.In order to maintain such speed descending, driver frequently uses detent, causes brake temperature to raise.

S103: according to detent material and the performance of the current lorry of current achievement in research and China, just lorry brake hub brake safe temperature in long downslope driving process is decided to be 260 DEG C;

S104: utilize Meng Takaluo (MonteCarlo) method to calculate the fiduciary level of longitudinal gradient Truck brake safe, result of calculation is used for evaluate the security of Longitudinal Slope Design, utilize mean inclination and length of grade that the target reliability degree inverse of brake safe is corresponding, this process is the reliability design of long slope sections;

Fig. 2 is MonteCarlo method calculating process

S201: by i, M, N assignment 1,0,5000000 respectively;

S202: by the parameter discretization of temperature rise functional relation;

S203: whether judgement sample is finished;

S204: export result of calculation;

S205: parameter is updated to inside power function;

S206: judge whether the result of calculation substituting into power function satisfies condition;

S207: perform a computing;

S208: perform a computing;

Jump to S203, complete and once circulate, then perform said process again;

Fig. 3 is the mutual conversion of lorry descending Process Energy;

S301: potential variation value Δ E;

S302: tire and road surface consumed energy E ₁;

S303: detent absorbs ENERGY E ₂;

S304: vehicle body and air consumption ENERGY E ₃;

S305: adopt the energy that foundation brakes absorbs;

S306: adopt the energy that auxiliary brake absorbs;

S307: adopt the energy that engine braking absorbs;

S308: adopt the energy that exhaust brake absorbs;

S309: adopt the energy that retarder brake absorbs;

Fig. 4 is the gross combination weight distribution plan of embodiment 2;

Embodiment 2

As the total length of grade 10.4km of Zhang dragon high speed K 74-K85 section of one of typical long and steep downgrade Accident Area, mean inclination 4.134%, Longitudinal Slope Design table is as table 1;

Representative vehicle, the gross weight of lorry needs to investigate in charge station, and investigation is in table 2 and Fig. 4;

Table 1 Zhang dragon highway is grown up the Longitudinal Slope Design table in section, slope

Table 2 vehicle composition investigation result

The calculation process of Fig. 2 is platform with MATLAB, has worked out highway longitudinal gradient reliability calculating program ZPRC.The order of ZPRC Calling MATLAB related function, the gross mass result above-mentioned investigation obtained fits to normal distribution, and carries out discretize; By above-mentioned each parameter is substituted into computation model, can calculate the fiduciary level of this section of longitudinal gradient, result of calculation is as table 2.This illustrates, the lorry of according calculation condition is when this sections of road, and the temperature of detent can exceed critical safety temperature 260 DEG C, and lorry brake failure can occur;

Result of calculation is consistent with the investigation result of document to the vehicle that meets accident.The accident lorry of document to this section is dissected, and finds that the friction disc of its detent carbonizes, burns, and crackle appears in brake hub, local also exists blue phenomenon.These phenomenons all cause because brake temperature is too high;

Table 3 Zhang dragon highway long downslope reliability calculating result

Claims (4)

1. a reliability design approach for long slope sections, is characterized in that, comprises the steps:

1) the brake hub temperature rise functional relation about the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperature is built;

2) reliability model of lorry descending process brake safe is set up;

3) fiduciary level of covering tower calot's method calculating longitudinal gradient Truck brake safe is utilized, based on reliability design approach, by Generally Recognized as safe and limiting safe two security arrangements, calculate the Generally Recognized as safe Maximal slope length corresponding to different average gradient values and the limiting safe Maximal slope length of highway composite grade respectively;

4) by step 1) in formula (2), formula (3), formula (4) formula substitute into step 1) in formula (1) in, by step 3) in, temperature is less than safe temperature T _sprobability, evaluate the security of Longitudinal Slope Design, utilize the target reliability degree of brake safe, inverse goes out length of grade corresponding to different mean inclinations, completes the design of the different mean inclination of longitudinal gradient and the length of grade of correspondence.

2. the reliability design approach of long slope sections according to claim 1, it is characterized in that, step 1) in, constructed brake hub temperature rise functional relation based on indoor and field test, this relational expression comprises the parameters (see formula 1) such as the gradient, length of grade, the speed of a motor vehicle, car gross weight, detent initial temperature, environment temperature.Wherein, the initial temperature of brake hub and environment temperature are all obtained by pilot survey data; Assuming that lorry gross weight Normal Distribution, expect it is calculate (see formula 4) at MATLAB platform invoke function command according to pilot survey data with variance; Based on the achievement in research of domestic scholars, the speed that lorry travels at long and steep downgrade meets normal distribution, expects all there is certain relation (see formula 2,3) with standard deviation.

T＝T(v,G,i,L,T ₀,T _a)(1)

Lorry is in the relational expression of long and steep downgrade average velocity about the gradient, and velocity standard difference about the relational expression of average velocity is

$\begin{array}{cc}{\mathrm{\μ}}_v=\stackrel{\‾}{v}=\stackrel{\‾}{v}\left(i\right)& {\mathrm{\σ}}_v={\mathrm{k\μ}}_v\end{array}---\left(2\right)$

According to about research lorry is in the travel speed Normal Distribution of long and steep downgrade, namely

V～N(μ _V,σ _V)(3)

Its Normal Distribution of the actual load-carrying hypothesis of lorry, namely

G～N(μ _G,σ _G)(4)

In formula: T-brake temperature (DEG C); T ()-funtcional relationship; average speed (the kmh of-lorry ^-1); Travel speed (the kmh of V-lorry ^-1); The gross weight (N) of G-lorry; I-mean inclination (%); L-length of grade (km) T ₀the initial temperature (DEG C) of-detent; T _a-environment temperature (DEG C); N ()-normal distribution; μ _vaverage speed (the kmh of-lorry ^-1); σ _vstandard deviation (the kmh of-lorry the speed of a motor vehicle ^-1); μ _gthe mean value (N) of-lorry gross weight; σ _gthe standard deviation (N) of-lorry gross weight.

3. the reliability design approach of long slope sections according to claim 1, it is characterized in that, step 2) in, using the critical safety temperature of wagon brake brake efficiency decline as constraint condition, set up the reliability expression of lorry descending process brake safe:

P＝P(T≤T _s)＝P(Z≤0)(5)

In formula: Z=T-T _s; T _sthe critical safety temperature (DEG C) that-brake usefulness declines; The fiduciary level of P ()-freight car braking safety, also namely lorry brake hub temperature of lorry in long downslope driving process is less than or equal to T _sprobability.

4. the reliability design approach of long slope sections according to claim 1, is characterized in that, in step (3), utilizes and covers the reliable of tower calot's method calculating freight car braking safety.The random number of each stochastic variable of obeying known distribution is produced by programming, and substituted in power function Z, in sample N, find the number M of content with funtion function Z≤0, as N → ∞, try to achieve brake safe fiduciary level according to Bernoulli law of great numbers, expression formula is:

$P=\underset{N\→\mathrm{\∞}}{\lim }\frac{M}{N}---\left(6\right)$

In formula: P is the fiduciary level of freight car braking safety, M is the number of times of content with funtion function Z≤0, and N is sample number.