The section size of the roadway is determined in the following aspects:
First, the determination of the height of the roadway
The dimensions of each part are determined by the following formula:
H o =h o +h 2 ,mm
H o - the net height of the roadway (the maximum height that can be used to remove the thickness of the bracket), mm;
Ho-arch height, mm;
When f≤3, ho=(1/3)B,mm
When f≥3, ho=(1/2)B, mm
When f>8, 
B-wayway net width, mm;
h 2 - the wall height of the roadway, mm;
h 2 =h 1 +h a
Where h 1 - the height of the track surface to the arch base is determined according to the height of the transport equipment and the height of the sidewalk, mm;
The height of the ha-way surface to the track surface is generally 160 mm.
After obtaining the net height of the roadway, plus the thickness of the bracket and the filling material, and the thickness of the ballast, the tunneling height H can be calculated.
H=H 0 +d+d 0 +h b ,mm
Where h b - the thickness of the ballast, taken 180 mm;
D-stent thickness, take 180 ~ 400mm;
d 0 - filling thickness, take 50mm.
Figure 1 shows the relationship between the height dimensions of the roadway.
Figure 1 Arched roadway section size
Second, the determination of the width of the roadway
Determine by the following formula:
Net width B=m+A+n (monorail), mm
B=m+2A+n+b (double track), mm
In the formula, the distance between the most protruding part of the transport device on the side of the m-lane and the most prominent part of the bracket. Generally not less than 200mm or 250mm;
A- The maximum width of the motor car or mine car used can be found from the transport equipment specification sheet, mm;
The distance between the most prominent part of the transporting equipment on the side of the n-roadway pedestrian and the bracket should generally be above 700mm; the minimum clearance between b-transport equipment should be no less than 200mm.
Third, the net cross section S roadway and tunneling net leg section S determined by the formula
S net = B (h 2 +0.26B), m 2 three-heart arch roadway
S excavation = B (h 2 +0.39B), m 2 semi-circular archway
When the air volume is constant, the smaller the roadway surface, the greater the wind speed. In the safety regulations, different types of roadways have their maximum allowable wind speed, so for the net section of the roadway, it is also tested according to the maximum allowable wind speed:
Where the wind speed of the v-lane, m/s;
Q-the amount of air passing through the roadway, m 3 /s;
v allowed - the maximum wind band allowed by the safety regulations, m/s
After the wind speed test is passed, the excavation area can be calculated according to the support thickness and the clean roadway area. In practice, due to the randomness of the blasting, the excavation section is often larger than the calculated section.
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