大厚度坚硬岩层  hard and massive overlying strata

厚层坚硬岩层  hard and massive strata

坚硬厚层岩层  hard and thick stratum

坚硬致密弱研磨性岩层  massive and hard to grind layer

粗粒坚硬岩石  ferric oxide

极坚硬岩石  Super-hard Rock

坚硬层  stiff layer

坚硬岩石  qinling tunnel; hard rock mass; hard rock

坚硬岩石地区  hard rock country

坚硬岩石井壁取心器  hrct; hard rock coring tool

坚硬岩石巷道  hard rock roadway; mine roadway in hard rock

表土下硬岩层的顶部  rock head

超硬岩层  hydraulic double wheel groove milling machine

淬硬层硬度  hardened layer hardness; Hardness of Hardened Layer

厚硬岩层  hard-and-thick strata

硬岩层  shelly formation

硬岩层中钻进  rough drilling

硬岩层钻井  hard-rock drilling

岩层层理  rock stratification