Brief: Core barrel double shells specially are used drilling for deep, large and toughest pile.Inner core barrel drill first and work as a centerizer .The outer core barrel drill and reaming.Ensuring the verticality of the pile.
Brief: Core barrel double shells specially are used drilling for deep, large and toughest pile.Inner core barrel drill first and work as a centerizer .The outer core barrel drill and reaming.Ensuring the verticality of the pile.