Hi, My name is Dogan. I work for a special company about tunnel. I have just worked in a tunnel be new an engineer in Turkey ..I found your mail adress on the Internet. I want to ask a question to you. I wonder, How can applications of self-drilling bolt in tunnel and what the bolt (self-drilling anchor) must be injection pressure? Thank you for give information of this subject..Best regards, dogan. I want to receive: