What are the different Rock Excavation Methods

 Rock excavation contractors have dated explosive or blast methods for rock excavation. Nowadays, rock blasting uses various explosives with different types and performance properties. Higher velocity blasts can be used for relatively sturdy rock to shatter and convert it into pieces. In contrast, soft rocks use low-velocity explosives to create more gas pressure and a more significant heaving effect.

Here are other explanations of various rock excavation methods.

Cushion blasting is performed after significant blasts. Larger drill holes are used with tiny diameter, lightly loaded distributed loads and the space around the explosive is filled with small pieces of rock to cushion the explosive force. Doing so reduces the amount of radial destruction around the borehole and reduces borehole traces. The large diameter holes allow blasting in the underlying area up to 30 m (100ft). The procedure produces a final slope face. One great thing about this procedure is that it can be performed on all types of rocks.

But, pre-split blasting methods are not very common. Slope face is more prone to ravelling, and a specific area is recommended at slope ground and base.

Another method is step drilling that involves larger diameter drill holes drilled vertically and used as production blasting. A slope face is manually made along the base of blast holes. If properly selected, the final slope face shows minor signs of discharge. It can be used when sloped controlled blasting cannot be used for rock excavation and is best used in moderately to highly fractured rock.

The methods mentioned above' cons would include extensive damage to the slope or inadequate base fracturing if not appropriately designed. Thus, step drilling cannot be used without extensive experienced of the driller and blasting engineers. Also, it is not advisable to use step drilling for hard competent rock.

Procedure for Excavation in Rocks

Excavation in rock requires drilling and blasting that should be done under the coordination of competent and responsible supervision.

The selection of technique and equipment depends on the depth and the flexibility of rock excavation & proximity to structures or hazardous areas. A compressed air-based jackhammer can be employed quickly for smaller and breakable rocks.

Chemical rock fissuring can be used for hazardous areas where explosions and heavy blasts are not allowed, such as working plants, Refineries, etc.

For more giant areas, excavator mounted Hydraulic hammers can be employed for braking the heavy rock. For the allowed regions for blasting & explosion, rock excavation contractors can use blasting methods after prior approval.

But before using the technique mentioned above, contractors should submit their chart with the contractor or customer. Jack driller can be used for drilling shallow rocks. The blasting operations shall be carried at a prefixed time with all the written safety precautions. The loosened rock should be removed using an excavator & stored in specified areas. Designers concerns should be taken before deciding. Any over-excavation or irregular foundation bottom shall be filled with lean concrete before rock excavation.