厚覆盖岩层 meaning in Chinese

heavy cover

3d fem analysis on ground surface deformation caused by mining under thick rock overburden
厚覆盖岩层下采矿引起地表变形的三维有限元分析
Research on deformation and subsidence characters of ground and surrounding rock induced by underground mining under thick covering terrain by model test
厚覆盖岩层条件下地下采矿的地表及围岩变形破坏特性模型试验研究