one ）The clear distance between the two tunnels in Huhuang shield section of Shenzhen Metro Line 2 East extension line is 1.71m-2.0m, and the vault buried depth is about 14m. Within the scope of overlapping tunnels, the stratum is mainly quaternary new artificial filling soil, alluvial proluvial cohesive soil layer, sand gravel layer and residual soil layer, and the underlying bedrock is tuffaceous siltstone of Middle Jurassic Tangxia formation (an earlier example in China).
two ） The minimum clear distance of overlapped section of civil engineering section 2227 of East extension line of Shenzhen Metro Line 2 is 1.36M. The overlapped tunnel is basically located in the fully, strongly and moderately weathered tuffaceous siltstone stratum, where the upper part is soft and the lower part is hard.
three ）The minimum clear distance between Laojie station and shaibu station of Shenzhen Metro Line 3 is 1.6m. The section tunnel mainly passes through completely weathered gneissic granite layer, and some sections have residual layer and strongly weathered gneissic granite.