... arrangement.0.50~1.20220~40TGA114114Very soft with low compressive strength strength and high drillability,such as soft shale,clay and ... surfaces.0.27~0.70200~80TGA115115Very soft with low compressive strength strength and high drillability,such as soft shale,clay and ... surfaces.0.25~0.70200~80TGAT115115Very soft with low compressive strength strength and high drillability,such as soft shale,clay and ...