A field trial to test the efficiency of induced partial saturation and horizontal drains to mitigate the susceptibility of soils to liquefaction

Within the European project LIQUEFACT some activities have been devoted to the experimental verifcation of the efectiveness of two techniques in the mitigation of soil liquefaction susceptibility: induced partial saturation (IPS) and horizontal drains. After a preliminary check of their efciency via centrifuge tests, the two techniques have been studied by means of some large scale shaking tests carried out in a feld trial located in the Emilia-Romagna Region (Italy). A preliminary extensive in situ and laboratory investiga tion was necessary to identify the shallow liquefable soil layer in which the mitigation techniques and the monitoring instrumentations (pore pressure transducers and geophones) had to be installed. Both techniques required the installation of horizontal well screens via a directional controlled drilling technique: the pipes were used as drainage systems (linear HDL and rhomboidal confgurations HDR) or for the air injection in the area treated with IPS technique. The in situ experimental evidences showed that both techniques are able to avoid liquefaction triggering, that on the contrary was attained during the tests in the untreated testing area. The processing of in situ data highlighted that the efciency of the two techniques is strictly related to chosen arrangement of the horizontal drains and the induced degree of saturation.