Italian ground engineering specialist Trevi has set up a Soilmec SM21 micro-drilling rig in St Mark’s Square, Venice, as part of a project to stabilise the famous 99m high Campanile bell tower.
The tower’s existing foundations will be strengthened by strapping a belt around them, consisting of two sets of 60mm diameter titanium bars.
The first strap will be constructed 400mm below the pavement, with the second a further 2.5m below that.
The straps will be installed in seven chambers, which are being formed using piles installed by the Siolmec rig.
The machine arrived on site by water, having been loaded onto a pontoon at the pier at Cavallino Treporti, on the edge of the Venice lagoon. It was then moved to the work site surrounding the bell tower on a specially built platform capable of efficiently distributing the machine’s 22t weight.
A platform was determined necessary after evaluations showed that the Euganea grey trachyte paving slabs at the start of the route could withstand a maximum load of only around 3kN/m². The platform was built using 150mm of sand and a layer of neoprene, covered with timber beams with I-beams anchored to them.
As the platform could not cover the entire 160m of the route, the drilling machine was moved in four 40m stages.
Work to strengthen the tower foundations is scheduled for completion some time in early 2012.