Site characterization by seismic dilatometer (SDMT) in the city of L'Aquila

This paper presents a review of results obtained by a large number of seismic dilatometer tests (SDMT) carried out in the area of L’Aquila (Central Italy), after the April 6th, 2009 earthquake. Due to the characteristics of the soils (mostly coarse-grained, nonpenetrable materials), SDMT measurements were generally performed in backfilled boreholes, using the technique briefly described; in these conditions only the shear wave velocity VS, without the other DMT parameters, was measured. The test results illustrated in the paper include: (a) SDMT typical results obtained by the normal penetration procedure (in a limited number of sites, mostly silts); (b) VS-only profiles obtained by the backfilled borehole procedure; (c) comparisons of VS profiles obtained by SDMT and by other techniques (Down-Hole, Cross-Hole, surface waves tests); (d) comparisons of VS measured by SDMT and those estimated from mechanical DMT data. The VS profiles provided by SDMT, combined with the information obtained from geological data and from other investigations, including boreholes down to a maximum depth of 300 m in the city centre, have been used for the soil characterization in numerical seismic response analyses. An example is illustrated in the paper.