The unique character of the mines at Combe Down necessitated the introduction of a number of innovative engineering solutions developed by the project.
Hydrock's specialist face excavators were developed to drive the roadway headings within the confined underground environment. The final versions of these machines were powered solely by electricity which removed the issue of emissions and reduced the noise impact on both workers and bats. These machines boosted productivity significantly and improved health and safety because the periods of exposure for the men at the working face were significantly reduced.
Previous experience showed that foamed concrete starts to break down at pumping distances of greater than 280m due to the effects of excessive pressures needed to pump this distance. Hydrock and Pro pump developed unique specialist high production in-line foaming systems for the placement of foamed concrete at distances of up to 1km from the batching plant. The placement of foamed concrete was developed further to allow a sprayed system to be operated to seal mine margins at distant points of the mine where other technologies could not be efficiently utilised. Mini-agitating systems were developed called 'bullets' which allowed small quantities of foamed concrete to be transported around the mine for the purpose of topping up small underground voids.Back to Top
Monitoring systems were devised by the Scott Wilson and Hydrock team to minimise the risk of surface concrete shows and give assurance that the concrete had reached the required level. These included the use of sacrificial infrared cameras and sacrificial electrical probes which would sound alarms when the concrete reached the mine roof.Back to Top
A number of different drilling systems were developed during the project to overcome the problems faced at the variety of locations where boreholes were required. these varied from accessing people's back gardens through houses to drilling within cellars and confined underground locations. A prime example of innovation was the design of a reach-over drilling rig which involved the attachment of a drilling mast to the arm of 360 degree excavator. This allowed boreholes to be drilled in inaccessible gardens without the need for demolishing walls, hence minimising the disruption to the residents and reducing the extent of reinstatements required.Back to Top
In order to construct the bat chambers in a safe and efficient way, Hydrock developed a system of installing high steelwork in a single phase of construction. Hydrock also developed a methodology that used shotcrete as a shutter for foamed concrete in the chambers, which led to time efficiencies and safer working conditions.Back to Top
Hydrock developed a non-mechanical stowing machine to overcome safety concerns with typical pneumatic systems. Based on a venturi principle, the stowers could be positioned either above or below ground, and allowed the aggregate to be placed within a stream of air as a result of a vacuum system. These stowers were particularly beneficial when placed at the bottom of a borehole or shaft, as they made use of the kinetic energy of the stone as it dropped into the mine. The equipment achieved high productivity rates and permitted close monitoring of the stowed aggregate as men could be safely stationed at the placement point.Back to Top