Method for removing hard rock and concrete by the combination use of impact hammers and small charge blasting

An excavation method for controlled fragmentation and removal of a material, comprising:

• (a) stemming a hole located in a free surface of the material;
• (b) providing a gas in the bottom of the hole;
• (c) pressurizing the hole with the gas, thereby causing a subsurface fracture to propagate outwardly from the bottom of the hole and fracturing at least a portion of the material adjacent to and surrounding the hole, wherein at least about 50% of the depth of the hole and some of the fractured material remain in place at the free surface after the pressurizing step;
• and
• (d) thereafter impacting the in place fractured material with a blunt object to remove the in place fractured material from the free surface, wherein the blunt object contacts the in place fractured material with a blow energy of at least about 0.5 kilojoules and a blow frequency of at least about 1 blow per second.

A method for controlled fragmentation and removal of a material, comprising:

• (a) inserting a blasting agent into a hole located in a free surface of the material and in a center portion of an excavation face of which the free surface is a part;
• (b) stemming the opening of the hole with a stemming material that is at least one of a granulated material or a stemming bar;
• (c) thereafter initiating the blasting agent when the hole is stemmed, thereby releasing gas into the bottom of the hole;
• (d) impeding the dissipation of the gas from the bottom of the hole with the stemming material, thereby fracturing at least a portion of the material surrounding the hole, wherein at least most of the the depth of the hole and some of the fractured material remain in place at the free surface after the material surrounding the hole is fractured;
• and
• (e) impacting the in place fractured material exposed at the free surface with a blunt object to remove the in place fractured material from the free surface, wherein the blunt object contacts the fractured material with a blow energy of at least about 0.5 kilojoules.