A  tunnel boring machine  ( TBM ) , also known as a "mole", is a machine used to excavate  tunnels  with a circular cross section through a variety of soil and  rock strata . They may also be used for  microtunneling . They can  bore  through anything from hard rock to  sand . Tunnel diameters can range from a metre (done with micro-TBMs) to 19.25 metres to date. Tunnels of less than a metre or so in diameter are typically done using  trenchless construction  methods or  horizontal directional drilling  rather than TBMs.     Hard Rock Tunnel Boring Machine  In hard rock, either shielded or open-type TBMs can be used. All types of hard rock TBMs excavate rock using disc cutters mounted in the cutter head. The disc cutters create compressive stress fractures in the rock, causing it to chip away from the rock in front of the machine, called the tunnel face. The excavated rock, known as muck, is transferred through openings i...
   1. I wish to all the engineers durability of granite, strength of M-60, Foresight of theodolite, Accuracy of Total Station, Success of STAAD and all loads are transfered successfully to columns, let almighty pre-stress U for all types of Unforced loads. HAPPY ENGINEERS DAY.   2. Everybody says Engineering is so easy that it it just like walking in a park But only Engineers know that park is called Jurassic Park. HAPPY ENGINEERS DAY.   3. You can be a Doctor and Save lives.You can be a Lawyer and defend lives. You can be a Soldier and protect lives. But Why to play with others lives? So we simply became engineers to screw up our own lives. HAPPY ENGINEERS DAY.   4. We design, We construct, We Observe, We initiate, We drive, We move, We accelerate the World, We are the gears of Progress, we are the future of the nation, we are the Engineers, and I am proud to be an Engineer. HAPPY ENGINEERS DAY.   5. Someone asked an engineer, Why you feel proud of being an engineer? He smiled and tol...