Proceeding of the 2018 DFI-EFFC International Conference on Deep Foundations and Ground Improvement, Rome, Italy, (DFI, EFFC)
Compaction Grouting Intervention for the Mitigation of Soil Liquefaction Risk within the Earthquake-Stricken Area of Emilia in 2012
Claudio Asioli, Eng., Federico Fanti, Eng. and Paolo Zuffi, Geol.
In order to reduce the liquefaction risk, it is common practice to modify the mechanical features of natural soils by means of active interventions. Compaction Grouting is one of the most widely used technologies, since it generally achieves very good results in terms of costs/advantages. The paper describes the design criteria employed and the achieved results for the soil consolidation intervention carried out within the earthquake-stricken area of Emilia (May 2012); upon said area a new primary school and kindergarten were built. In addition to the liquefaction analyses - which were carried out according to the simplified method proposed by NCEER and which show the presence of a potentially-liquefiable layer of saturated silty sand between 1.8 m and 7.0 m from ground level - the paper also illustrates the calculation procedure developed for the compaction grouting columnsí design. In particular, the text focuses on the two phases into which the design can be divided: assessment of the minimum soil strength to be obtained in the liquefiable layer in order to guarantee the safety factor required; setting out of columnsí geometry (pattern, diameter and spacing) to be adopted in order to reach the requested density degree. Similarly to the liquefaction potential index (LPI) defining the degree of risk, a new index soil improvement index (SII) is proposed to provide directions on the soil improvement that needs to be obtained. Moreover, said index can be employed also to assess the effectiveness of the accomplished intervention. Finally, the paper describes monitoring and additional soil investigations results, both for the assessment of the preliminary test field - which is necessary to validate the design theoretical analyses - and for the final control tests.
|article #3039; publication #1040 (ROME-2018)|