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Ramp is inclined mine opening used to provide access between levels for different types of diesel equipment. Its main property is its inclination can be expressed as slope, grade or angle between ramp trajectory and horizontal plane (Table 1).

Table 1 Common expressions of inclination
Incline
 
 
Figure 1 Relation between slope, grade and angle
 

   
 

Slope (1:7) means that ramp advances 1m vertically for every 7m of its horizontal projection. Considering this, length of the ramp or its straight section can be expressed as follows:

$l=\sqrt{l_{p}^{2}+\Delta {{h}^{2}}}$

 

Where:  
    $l$ - ramp length (m)
    ${{l}_{p}}$ - length of horizontal projection (m)
    $\Delta h$ - vertical distance passed (m)

 

Figure 2 Slope of the ramp

 

Common situation is that ramp has great length and it has to be put into constrained space and therefore straight sections have to be combined with curves. Main parameters for each curve are its radius, center, overall angle and starting and ending points. Radius of the curve has to be high enough so equipment can move through it without significant speed reduction and additional moving. Usually radius of 20m will provide this conditions, however, sometimes du to the space limits it can be lower, but not bellow 15m. Many confuse minimum radius of ramp with turning radius of equipment that is found in catalogues. Minimum turning radius is simply minimum that equipment can cope with, but with minimal speed. Ramp should provide best possible kinematics for the equipment without creating bottlenecks. It is must that straight sections are tangents to the curve in order to keep kinematics satisfied.

Figure 3 Curve section of ramp

 

 

Length of the curve projection or the arc length is equal to:

 

${{l}_{p}}=\varphi \cdot R$
Where:
    ${{l}_{p}}$ - length of horizontal projection (m)
    $\varphi $ - overall angle (rad)
    $R$ - curve radius (m)

 

 

Length of the ramp is:

$$l=\frac{l_{p}}{\alpha }$$
Where:
    $\alpha $ - inclination of ramp (°)

 

 

Main principle when designing the ramp should be to keep it as simple as possible having in mind that somebody should drive every day through that ramp. Use straight sections as much as possible, avoid making double curves, keep their radius as high as possible, avoid spirals if possible.

 

 

 

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