PRETENSIONED ROCK BLASTING METHOD

摘要

PURPOSE: A pretension arm blasting method is provided to accurately excavate rock and minimize overbreak and damage by inserting pretension induction units in tension induction holes to crush the rock with tension of the pretection induction units. CONSTITUTION: A pretension arm blasting method comprises the steps of: forming tension induction holes(5) and charging holes(7) in rock(3) along a designed plane(1) of a tunnel or slope, wherein the interval of the tension induction holes is the minimum distance to form a designed section out of connected crack surfaces; inserting pretension induction units in the tension induction holes; expanding the pretension induction units with one of hydraulic pressure, pneumatic pressure, and mechanical pressure to generate tension at the right angle to the designed plane of the tunnel or slope in each tension induction hole; placing gunpowder in the charging holes; blasting the gunpowder in the charging holes to excavate the designed section of the tunnel or slope first; and excavating the designed section of the tunnel or slope secondly using tension.