# Research on Selection and Matching of Truck-Shovel in
## 2 Selection and Matching of Shovels
### Analysis of Reasonable Number of Shovels  
The key problem of shovel selection is to determine a reasonable number of shovels to meet the production requirements, so as to select a suitable bucket capacity according to  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multirow{2}{*}{**Item**} & \multicolumn{2}{c}{**2015**} & \multicolumn{2}{c}{**2016**} & \multicolumn{5}{c}{**2017**} \\ \cline{3-14}  & & **Average** & **Average** & **January** & **February** & **March** & **April** & **May** & **June** & **July** & **August** & **September** & **October** \\ \hline \multirow{3}{*}{ shovel} & attendance & \multirow{3}{*}{91.8} & \multirow{3}{*}{89.2} & \multirow{3}{*}{93.1} & \multirow{3}{*}{88.4} & \multirow{3}{*}{91.2} & \multirow{3}{*}{86.6} & \multirow{3}{*}{88.7} & \multirow{3}{*}{76.0} & \multirow{3}{*}{76.0} & \multirow{3}{*}{90.9} & \multirow{3}{*}{85.7} & \multirow{3}{*}{90.8} \\  & & & & & & & & & & & & & \\  & & & & & & & & & & & & & \\  & & & & & & & & & & & & & \\  & & & & & & & & & & & & & \\  & & & & & & & & & & & & & \\  & & & & & & & & & & & & & \\ \hline \multirow{3}{*}{ truck} & attendance & \multirow{3}{*}{87.2} & \multirow{3}{*}{82.4} & \multirow{3}{*}{79.8} & \multirow{3}{*}{74.3} & \multirow{3}{*}{73.1} & \multirow{3}{*}{70.9} & \multirow{3}{*}{76.8} & \multirow{3}{*}{83.5} & \multirow{3}{*}{86.6} & \multirow{3}{*}{83.5} & \multirow{3}{*}{86.6} \\  & & & & & & & & & & & & & \\  & & &a reasonable number of shovels. It is important to neither choose too many shovels nor too few. The number of shovels selected cannot be too large or too small. If the number of shovels is small, once the equipment fails, it will directly affect the mine capacity, causing economic losses, high risk and low reliability. Moreover, due to the excessive concentration of equipment capacity, it is not conducive to long-term balanced mining in the stope; if the number of shovels is large, the working face of the stope is increased, the management is complex, and the production cost is increased, so it is difficult to realize large-scale and high-intensity mining. The actual number of pieces of equipment in attendance is a random fluctuation value, and follows the binomial distribution law [20]. Assuming that there are \(N\) registered shovels, the average attendance rate of each shovel is \(p\), and the probability of the actual number of attendance stations is:  
\[P(X=m)=C_{N}^{m}P^{m}(1-p)^{N-m}\,\ m=1,2,\ldots,N \tag{2}\]  
where \(m\) is the number of equipment units in attendance at the same time, and \(P\) (\(X=m\)) is the probability of m equipment units in attendance at the same time. \(C_{N}^{m}\) is the number of combinations when m equipment units in \(N\) registered shovels are on duty at the same time. Table 2 shows the probability of the actual number of shovels in attendance under the condition of a different number of registered shovels. The attendance rate of a single shovel is 89%. According to the efficiency of existing large excavating equipment and the need for mining and stripping volume, it is generally required that at least three working platforms should be arranged in the stope at the same time to carry out mining and stripping operations [19]. It can be seen from Table 2, considering the reliability index 0.85, in order to ensure that at least 3 shovels are in continuous operation state, at least 4 registered shovels should be selected. When the number of registered shovels is 6, the probability of ensuring the continuous operation of 3 electric shovels is close to 1.0, indicating that the continuous increase of the number of shovels has no obvious effect on the production guarantee of the mine, and it is easy to lead to the situation that the stope has too many requirements and the working face cannot be rationally arranged. At the same time, according to the average attendance rate of 80% of shovels in Chinese mines, the results show that in order to ensure at least 3 shovels in continuous operation, it is more reasonable to choose 5-7 registered pieces of equipment.