Tuesday 10th January – levelling and alignment


Today I started thinking about the bridge re-installation. In preparation we shifted module E1 sideways into alignment. Having observed some of the issues on the previous module I made suggestions on changes in the board layout. The chief engineer has loads of experience working in Antarctica and adapts the work method to suit the conditions and what is working at that time.
The levelling of the buildings approach has been, to set modules E1 / bridge / E2, and then followed by all the other modules either side. As we discovered during my initial work at site VI, to engage the locking pins successfully a minimum leg extension is needed.  However the maximum leg extension is around 1460mm (+/-50mm), so we are aiming to have all the modules leg extensions in the range 1275 to 1375mm, and not extend any leg more than 1410mm as a maximum. This means that we will need to get the levels in the snow pretty accurate given the tolerances required for differential snow melt and compaction. This will be particularly difficult on the lower part of the site where we will need to introduce 700mm high berms to level the modules through.
Consequently I undertook lots of levelling work on module E1 as it sits at the top of the slope and will be the unit with the lowest leg extensions, and so, critical to inserting the pins. So we will need to set the minimum leg extension here, and then replicate the snow levels elsewhere to work within the leg extension range that we have set ourselves.

As we do not have time to level the modules down the slope on the snow berms I have to work out how we can use the module tolerances in the Trelleborg to set up from the bottom of the slope and get the E2 module reasonably close to the E1 module to allow the bridge to be re-connected. This requires me to slope the modules between the legs, create up to 100mmm steps at the Trelleborg junctions, and this allowed me to get the E2 module to within 200mm of the set E1 module height. The 18m long bridge was easily capable of managing this step change although the bearings needed keeping an eye upon.
I also checked the bridge length to make sure that when we finished pulling the E2 module onto the H1 module that we had adequate tolerance to drop the bridge in. The bridge lift went ahead this evening, the pins connection to the E2 module went back in easily and we winched the E1 module letterbox onto the bridge projecting beams that form the sliding connection.

My son Daniel left for his travels today so in the evening I spoke to Luci to make sure she was ok.