"Per scavo a sezione aperta si intende quello occorrente per dar luogo al vano terra per cantinati di nuova costruzione, per corpi di fabbrica interrati, per piani di appoggio di platee di fondazione ed in genere per scavi al disotto del piano di campagna, aventi la larghezza superiore all'altezza, eseguiti a cielo libero. "
http://www.vomero.it/tecnica/tariffari/2004 Basilicata word/...
In Italian scavo a sezione aperta is the same as scavo di sbancamento. The English for sbancamento is simply excavation. So I think you can focus on the idea of "cielo aperto".
Many occurrences for "open area excavation" on google

An interesting link here. "Work from the top to the bottom. As well as working from the known to the unknown, also as far as possible, remove material at the physically highest level in the context and work towards the lowest. This is best practice because loose spoil will not then fall onto and contaminate the surface being worked on. In this way blurring detail that might have been instructive to the excavator is avoided."
http://en.wikipedia.org/wiki/Excavation

http://www.answers.com/topic/open-area-excavation
"One of the principal means by which archaeological data is captured and recorded, excavation involves the systematic exposure of deposits that are then taken apart. There are a number of different techniques of excavation, such as open area excavation, , quadrant excavation, and Wheeler system, each having its own strengths and weaknesses. Selecting a method that suits the kind of site under investigation and the questions being asked is an important preliminary to any excavation project. A widely held principle, however, is that excavation should proceed by removing the layers and deposits within the site in the reverse order to which they were laid down in the first place. The different methods also carry with them implications for the way things are recorded, although plans, sections, photographs, notebooks, finds indexes, context records, and sample logs will be found in almost all of them. Not all studies can be done on site (desirable though that is), and samples of material and finds have to be cross-referenced to the deposits from which they came so that they can be examined later in the laboratory. Excavation is destructive, and it is costly in time and resources. New technology such as digital recording systems is playing an increasing role on fieldwork projects, and frees the archaeologists to spend more time interpreting what they are finding as they go along."
http://www.answers.com/topic/excavation
http://ads.ahds.ac.uk/catalogue/adsdata/cbaresrep/pdf/064/06...
http://pb-archaeology.blogspot.com/2008/04/what-are-excavati...


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Note added at 4 ore (2008-07-27 14:54:45 GMT)
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@ K donnelly: the link you have provided shows the opposite: a cross section is an excavation in the vertical plane (a sezione obbligata o scavo di fondazione). An excavation "a sezione aperta" is in the horizontal plane, an exacavation in plan that is the opposite of one in section, as the link reports

http://en.wikipedia.org/wiki/Archaeological_plan