Typical Blasting Methods for Structural Engineering Operations

Table of Contents

1. An Introduction to Blasting Technology

2. Blasting Technology Methods

3. Pre-Splitting

4. Smooth Blasting

5. Line Drilling

6. Perimeter Blasting

7. Cushion Blasting

8. Blasting and its Consequences

9. Safety Steps for Drilling Operations

An Introduction to Blasting Technology

Blasting technology is an essential part of the construction process to perform structural engineering activities. Blasting is the process of cracking rock material by using a small amount of explosive substance so that the rock is destroyed into several pieces. In the past, black powder and dynamite were used for the explosive process. Blast design and execution are important for successful rock removal operations. The use of excessive explosive material at the blasting site may cause unwanted caving. Blasting is used for both the rock removal process and underground mining operations. Currently, the most common explosives used in mining industries are ammonium nitrate, slurries, and emulsions. The type of blast design and explosive material consumption depends on various factors; the most common factors are rock type, density, strength, and damage condition of the existing rock base. Structural engineering exam review courses recap geotechnical engineering properties of rocks for foundation design.

Blasting Technology Methods

When the drilling process is over, it is time to start to blast to break up the rock required for excavation.  The blasting method is used for rock excavation. Controlled blasting is a technique of blasting, which is used to reduce the amount of over break and to control ground vibrations. The different types of controlled blasting techniques are pre-splitting, smooth blasting, line drilling, perimeter blasting, and cushion blasting. 

Pre-Splitting: The purpose of this technique is to reduce the impact of ground vibrations on the other side of the pre-split line.

Smooth Blasting: This technique is used mostly in underground blasting and muffle blasting as a solution to prevent fly-rock. 

Line Drilling: This is the earliest controlled blasting method used for explosive activity. This method drills the perimeter of walls to the full depth of the excavation prior to blasting. This kind of drilling is not as noisy when compared with other types of drilling.

Perimeter Blasting: This type of blasting is mostly used in underground excavation; the perimeter holes of the roof of headings and tunnels are drilled along the design in a parallel direction to the excavation.

Cushion Blasting: This type of blasting is applicable in surface trimming.

Professional structural engineers who are preparing for their SE exam must be familiar with blasting methods and their applications. 

Blasting and its Consequences

Blasting techniques and the proportion of explosives/blasting agents used to remove all rocky outcrops exhibit the least disturbance to the surrounding environment. The outcomes of any type of blasting techniques are fragmentation, muck pile displacement, ground vibrations, and oversized fly-rock fragments. The main materials used for blasting are Nitrate mixtures, Nitro-glycerine based explosives, Mono-methyl amine or Nitro-carbo nitrate based explosives, RDX, HMX, and LOX. The by-products of the explosive chemicals can cause environmental pollution and contamination.

Safety Steps for Drilling Operations

• Many accidents occur when working with drilling machines. Miners work with thread drill steels, and they work very close to the drilling machine. To avoid accidents during drilling operations, proper safety steps should be taken.
• Proper training must be provided to the drilling machine operator to follow the manufacturer's procedures when working with the driller.
• Manual handling should be avoided during the drilling operation.
• Operators should not wear loose-fitting clothing when working around drills. 
• The safety features of the equipment should never be ignored.
• Operators should be aware of emergency stop switches and ensure the switches are in working condition.
• The safe routing of pipes and cables should be provided so that they are not close to the spin around the drill.

Occupational Safety and Health Administration (OSHA) standards require project engineers to implement safety and precautionary measures for employees and the safety of the public. SE exam review courses refresh OSHA principles and standards for blasting operations.