Archive for December, 2009

09/10 Season - Module Move

When the early input team arrived on site at the end of winter one of the first jobs was to flatten out all the wind tails in front of buildings and containers and in all other working areas. The snow surface for the construction site and the main thoroughfares was compacted and groomed to provide a hard and safe working surface for men and machines. Each of the modules was then dug out of their wintering positions. To do this a huge amount of snow was removed and battered back around each module to provide working space. A shallow ramp was also formed in front of each module to enable it to be towed out to its new position on the summer construction line. Before towing the clad module the jacking concept was first tested. To do this each leg had to be raised, a 1m high pile of snow pushed underneath and then the leg lowered on to the pile before repeating the process on the next leg. Once all four legs were sitting on piles of compacted snow (no mean feat for a building weighing approximately 60 tonnes) the module then used its hydraulics to raise itself to a full operating height of about 4m. This allowed a bulldozer to get underneath and level the snow surface all around the skis providing a working surface for the team to fit the towing frame. Once the towing frame was fitted the module was lowered and a CAT Challenger together with a bulldozer were hitched to the front. The module was towed slowly up the ramp to the construction line.

Blue module move start Blue module moving
Starting the move of the blue module Blue Module moving

The skis do stick to the ice but once this “sticktion” is broken the module moves very easily.  The same jacking and towing regime was followed for all of the tented modules. The only change in the process was the tent skirts had to be raised and secured to allow access to the skis. Once on the construction line the modules were ready for the next stage of construction.

Site in 09 10 season
Construction site 09/10 season

Link | Posted by Mike in Construction on December 10th, 2009

After Winter 2009

After their second winter the clad module and tented modules were left in large wind scoops. The scoops around the tents were over 3m deep in places with even bigger wind tails of snow accumulated behind. The landscape around Halley station was no longer flat! It is planned to jack each module up every year to keep them above the surface and out of the wind scoops, although computer modelling and a 1:50 scale model test in the 06/07 season suggested that the station could survive two years if necessary as the aerodynamics of the station would prevent it from burying. The scoop around the clad module, which has remained static for two winters, has validated the testing. In the final layout all the modules will be orientated long-side on to the prevailing wind to keep the size of the wind scoops and wind tails to a minimum. Even though the blue module was left nose-on to the wind the shape of the scoop indicates how the aerodynamics of the module have worked especially when compared with the tents.

Module in Scoop Tent in scoop
Blue module in its wind scoop Tented module in its wind scoop
Link | Posted by Mike in Construction on December 1st, 2009