二衬裂缝
cracking of the secondary linings
水力压裂裂缝
Hydraulic fracture
hydraulic fracturing fracture
hydraulically created fracture
U形衬砌渠道
the lining of U Canal
U-shape canal with concrete lining
半封闭圆形衬砌
partially sealed circular lining
变截面液压台车衬砌
hydraulic truck lining with variable sections
不衬砌地下洞室
unlined underground cavern