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With pre-grouting the emphasis is on ground preparation, ahead of tunnel development. Post-grouting can generally be considered as rectification work rather than tunnel construction.

By rectification, we mean, that post grouting has been found to be necessary because pre-grouting has not been completely successful - or the risk was taken to forego pre-grouting in the aim of gaining time and saving money - or the extent of potential post-grouting was thought to be low relative to the cost of pre-grouting.

Regardless of the reasons for undertaking a post-grouting program, experiences from tunneling projects around the world have demonstrated that the costs of post-grouting to be from three to ten (3 – 10) times more expensive than pre-grouting, many times more difficult and success is not assured.

Injection grouting (pre-grouting) may be performed for any one or several of the following reasons:


Construction
  • Reduce water inflows to suit chosen construction method or to meet specified inflow parameters determined on serviceability requirements.
  • Stabilise and strengthen the rock mass in order to facilitate safe and high productivity tunnel development.
  • Prevent blast gases and other tunneling induced influences from adding additional stresses to the rock mass.
Operational
  • Reduce operating costs associated with water pumping and drainage.
  • Eliminate waterproofing membranes or reduce the reliance on waterproofing membranes to control water ingress.
  • Reduce the need for water and frost control.
  • Traffic safety – water/ice.
Environmental
  • Eliminate degradation of water table, both level and quality, with no disturbance of ecosystem.
  • Eliminate or control potential overburden settlement.
  • Reduce drainage and disposal of unwanted/contaminated drainage water.
  • Environmental issues have become more significant and are a major influence on the choice of grouting materials. In addition, occupational health and safety considerations are also of prime importance. These considerations cannot be ignored and new generation grouting materials provide the flexibility of choice.
- F. Papworth & B. Grant - Tunneling and Underground Construction Society (Singapore), 23rd March 2000.

Sovereign has been in the groundwater sealing and consolidation business since 1972 and has successfully sealed tunnels in Singapore, England, Australia, Hong Kong and the US.

Examples of our grout activities in tunnels are the Dartford tunnel in London England, Port Headland Harbor tunnel in Western Australia, Stone Cutters Island tunnel in Hong Kong, Gwithian outfall tunnel in Cornwall United Kingdom, Prospect water tunnel in NSW Australia, Hazelbrook sewer tunnel in NSW Australia. C156, C485, C486, C903, C935 in Singapore to mention a few.

Our grout NOH2O has successfully sealed tunnels during construction by grouting inflows in the excavated face. Repairs and rehabilitation has also been done – some by grouting the rock structure some by sealing the annulus and some by repairing joints and cracks in the concrete lining. Large inflows during tunnel excavation - up to 50 Gallons per second have successfully been sealed in a single shift.

Our Core competencies:
  • To seal unwanted ground water with no disruption to our clients operations.
  • To provide our clients with technically advanced quality products and services.
  • To provide services complying with all health, safety and environmental regulations.
  • To provide our services cost effectively and without delays.
Our Specialties:
  • We analyze geotechnical reports and design pre-grouting programs to deal with the area prior to excavation – shafts or declines. This will result in a dry area prior to mining.
  • During the annual conference of the ‘Institute of Shaft Drilling Technology’ (ISDT) held in Las Vegas (1991) a technical white paper was written on Sovereign, our products and systems outlining our capabilities also referring to past case studies.
  • Research and development - Currently research and development is taking place in both Canada and Central Africa at two of the wettest underground sites in the world.