Civil excavations

 

Rock excavations in urban areas

Rockbreaking in urban areas often involves many environmental constraints which must be carefully managed. These restrictions usually take the form of one or several of the following:

  1. Flyrock control or elimination
  2. Ground vibration control
  3. Airblast or overpressure control
  4. Noise control or elimination

By using NxbursT™ in conjunction with rubber mats for covering the charged holes, fly rock can be eliminated: noise and overpressure can be reduced to a minimum; and ground vibration can be reduced to low levels.

Demolition of reinforced concrete

Demolition of reinforced concrete structures often presents problems when using conventional explosives due to the tendency of the concrete to crack but remain anchored to the reinforcing bars, thus requiring many man-hours of oxy-acetylene cutting to complete the work.
The advantage that NxbursT™ brings to reinforced concrete demolition is that it removes the concrete cleanly from the reinforcing because the gas pressurises the space between the steel and the concrete, forcing it to crack and dislodge.

Trenching

Rockbreaking in trenching projects often involves removing shallow outcrops of hard rock at the base of the trench to enable an excavator to dig the trench to the required level. NxbursT™
brings several advantages to trenching projects
which include:

  1. No fly rock with minimal cover requirements for the shot
  2. Minimal noise and overpressure
  3. Low vibrations

Foundation excavations

Foundation excavations and footing excavations are often required to be precise so that concrete usage is minimised in the construction of the building. To achieve smooth and precise excavations requires controlled rockbreaking - an application which NxbursT™ is ideally suited to do.
Achieving precision rockbreaking in foundation excavations requires a practical drilling plan to ensure that at least one free face is available at all times to control the direction of the break.

Pass and boxhole excavations

NxbursT™ has been used to excavate vertical rock openings in situations where short passes were required to be excavated to a lower level, without interrupting or delaying production operations in the vicinity. One such ore pass excavation using NxbursT™ involved enlarging a 1.4 metre diameter raisebore hole into a 3.0 metre orepass.
The excavation of the 3m diameter vertical pass, which was 50 metres in length, was achieved by firing small sections on a continuous basis throughout the shift. The use of NxbursT™ produced a smooth profiling result around the perimeter of the pass.

Tunnel widening in sensitive areas

NxbursT™ has been used in several tunnel widening applications where the excavation had to be carried out without interrupting ongoing haulage or other critical operations in the vicinity. One such application involved increasing the width of a 3.5m by 3.5m haulage tunnel by 2 metres to allow a second rail track to be laid. The rockbreaking was required to be carried out whilst the haulage continued to operate with trains passing the excavation area during the shift. The widening of the tunnel was achieved with minimal fly rock and no damage was done to haulage installations.

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Reinforced concrete - before

Reinforced concrete - after

Pass and boxhole excavations