Report on the Current Situation of Laboratory Stress-Strain Testing of Geomaterials in Italy and Its Use in Practice

As far as laboratory testing is concerned, routine geotechnical design in Italy is mainly based on the results of odometer, triaxial and direct shear tests. These tests provide compressibility, undrained shear strength and shear strength parameters to be used in the framework of conventional simplified numerical analysis. The undrained shear strength and/or shear strength parameters are inferred from UU or CU triaxial compression tests performed on specimens 38 mm in diameter and H/D=2. The shear strength parameters are also inferred from direct shear tests performed under drained conditions. A booklet prepared by the Italian Geotechnical Society (AGI, 1994) suggests the recommended procedures for the execution of laboratory tests: grain size analysis, odometer, direct shear and triaxial. Anyway none of these suggested methods deal with the assessment of the stress-strain relationship of geomaterials. In a separate booklet (AGI, 1977) recommendations are provided in order to: - program geotechnical investigations - retrieve soil samples - draw stratigraphic and geotechnical logging - install piezometers - determine in situ soil permeability - perform in situ tests (CPT, SPT and FVT) The above mentioned documents are written in Italian and mainly follow the recommendations of the International Society (ISSMGE). There exist associations of commercial laboratories (ALGI) and contractors (ANISIG) that guarantee the execution of laboratory and in situ tests (including sampling and borehole logging) according to the AGI recommendations. A comprehensive review of AGI recommendations on both in situ and laboratory tests is currently in progress. The reviewed version will closely refer to the principles addressed by Parts 2 and 3 of Eurocode 7 (Geotechnical design). The Italian Ministry of Public Work (MLLPP) has recently established that Geotechnical Laboratories in Italy should guarantee some requirements and should follow given standards in performing laboratory and in situ tests on soils and rocks (MLLPP, 1999). According to the MLLPP the AGI recommendations will become mandatory. For those tests not considered by AGI it is suggested to follow the international standards such as ASTM, ISRM recommendations and BS 1377 - 5930. Advanced stress-strain testing is in practice required only for special projects such as microzonation studies and/or design of very important infrastructures especially in seismic areas.