ENGINEERING GEOLOGICAL AND GEOTECHNICAL INVESTIGATION OF LANDSLIDE EVENTS IN WILDFIRE AFFECTED AREAS OF ILIA PREFECTURE, WESTERN GREECE

In August 2007 Ilia Prefecture suffered one of the most devastating wildfires that have ever happened on European level. Approximately 870km2 , mainly forest and agricultural land, were lost, more than 60 people were killed, hundreds were injured and many villages suffered extensive damage. Heavy rainfall and human activities, favoured by the loss of vegetation and the overall susceptibility of geological formations in landsliding, induced the manifestation or reactivation of various scale landslide phenomena. In order to investigate and mitigate the problem University of Patras was commissioned by the Region of Western Greece to undertake an Engineering Geological and Geotechnical investigation. Site investigation accomplished in seven municipalities focusing on several landslide events with serious socio-economic impact and as a result many small scale cases were identified. In each one of these cases large scale engineering geological mapping was conducted and remedial and protection measures were designed

Centrifuge modelling of capillary rise

This paper reports results from centrifuge tests designed to investigate capillary rise in soils subjected to different gravitational fields. The experimental programme is part of the EU-funded NECER project (Network of European Centrifuges for Environmental Geotechnic Research), whose objective is to investigate the appropriateness of geotechnical centrifuge modelling for the investigation of geoenvironmental problems, particularly with reference to partially saturated soils. The tests were performed at the geotechnical centrifuge laboratories of Cardiff. Bochum. Manchester, and LCPC in Nantes. The aim was to determine the scaling laws of capillary rise under both equilibrium and transient conditions. In all laboratories, column wetting tests in fine poorly graded sands (Congleton Sand, Bochum Normsand, HPF5 Sand, and Fontaineblau Sand) were performed. Capillary rise above the phreatic surface of the sand model was distinguished in a continuous capillary zone (completely saturated) and a discontinuous capillary zone (partially saturated). The Cardiff Geotechnical Centrifuge Laboratory used matrix potential probes to follow the capillary rise of the continuous zone and, therefore, determine the suction above the phreatic zone during centrifuge testing. Ar Bochum, two cameras were used for optical and volumetric measurements, in order to follow the rise of the visible wetting front (upper limit of discontinuous zone) in the sand within the sample column. At Manchester. the movement of the wetting front was observed by video cameras over periods up to 8 h, whereas in LCPC pore pressure transducers recorded the changes in pressure caused by capillarity. A simple centrifuge similitude law for capillary rise in these sands has been established and the kinetic phenomena have been measured as a function of the gravitational field. The results from these experiments verify that both the continuous and discontinuous capillary zones are scaled at a factor 1/N whereas the time for rise seems to be scaled at a factor 1/N-2. This research suggests that capillary phenomena can be modelled using a geotechnical centrifuge. Therefore, centrifuge testing can be a useful tool for future modelling of boundary value problems involving complex transport phenomena. (C) 2001 Elsevier Science B.V. All rights reserved

Development of sensors, probes and imaging techniques for pollutant monitoring in geo-environmental model tests

In order to be able to track the movement of pollutant plumes during geotechnical centrifuge and other geo-en-vironmental experiments, a number of techniques have been investigated: fibre-optic photometric sensors, resistivity probes, resistivity tomography, and copper ion-selective electrodes. Methods of image analysis, signal processing techniques and multi-spectral image analysis were also explored and applied to images of moving plumes. In addition, an optical technique for detecting NAPL by cone probe was investigated. Their relative merits are discuseed. This work was conducted as part of an EU-funded network programme: NECER (Network of European geotechnical Centrifuges for Environmental Research), and this paper summarises the conclusions of the sensors and imaging working group