Bauer is installing piles at an altitude of 4,851m above sea level as part of the foundation works for a large millimetric telescope (GTM). This is being constructed for Mexico's Instituto Nacional de Astrofisica, Optica y Electronica in collaboration with the University of Massachusetts.
The GTM will comprise a radiotelescope capable of capturning radiation in the millimetric microwave band originating from the most distant parts of the universe. It will collect reading with a 50m diameter antenna mounted on a steel structure which is founded on a support tower which has to be highly rigid to limit differential movement of the antenna.
The site chosen for the GTM is Cerro la Negra, an extinct volcano 350km east of Mexico City. Ground conditions are volcanic rock consisting of compact, massive, very strong andesite. The altitude makes site conditions highly demanding of both workers and equipment.
Foundations to support the equipment consist of a 40m diameter circular concrete slab. The 90,000kN load will be transferred to 37 reinforced, fully cased, cast insitu piles with a diameter of 1,180mm and varying in length between 8.5m and 20.5m.
To speed pile installation Bauer was asked to work alongside a local company.
Bauer mobilised a BG22 drill rig equipped with rock tools, together with a BV1500 casing oscillator. This combination succeeded in completing piles in around one-twentieth of the time previously taken, says Bauer, with the result that piling work should be finished in around two months.