Construction Practice of Vertical Borehole with Large Diameter in Bedrock

Abstract:

According to the difficulties in construction of vertical borehole with large diameter in bedrock, the paper introduced the successful construction process of large diameter vertical borehole in bedrock and full-hole large diameter steel pipe laying by small diameter pilot hole, movable guide apparatus, large diameter borehole monitoring with small diameter pilot hole and large diameter expanding bit with advanced pilot.

Key words:bedrock; vertical borehole with large diameter; small diameter pilot hole; movable guide apparatus; large diameter expanding bit; hole deviation monitoring