Is tunnel lining dangerous?

The secondary lining of tunnel is dangerous. The construction workers working in the second lining of the tunnel are in danger of falling rocks, personal injury, collapse, falling and electric shock, so it is very dangerous. The secondary lining of the tunnel means that after the external support of the tunnel is completed, the steel mesh is arranged around the tunnel, and then the form is sealed by the secondary lining trolley, and concrete is poured at the same time, and finally an integral reinforced concrete structure is formed around the tunnel, which plays the role of bearing the upper stress and leaving enough space for the lower passage.