Sérgio D. N. Lourenço

Bio: Sérgio D. N. Lourenço is an academic researcher from University of Hong Kong. The author has contributed to research in topics: Soil water & Pore water pressure. The author has an hindex of 19, co-authored 70 publications receiving 977 citations. Previous affiliations of Sérgio D. N. Lourenço include Durham University & Cardiff University.

Soil suction monitoring for landslides and slopes

Abstract: Rainfall is the most frequent triggering factor for landslides and the development of early warning systems has to take account of this. It is suggested that direct measurement of pore pressure gives the most reliable prediction of failure of a slope. The amount of rainfall can be only a crude indicator of failure as the processes that occur between rain falling on a slope and the resulting pore water pressure change are complex, highly non-linear and hysteretic. The paper describes highcapacity tensiometers developed within the EU-funded MUSE Research Training Network that have been used for measuring suctions in slopes. High-capacity tensiometers are capable of direct measurement of pore water pressure down to −2 MPa and are also able to record positive pore water pressures. Two methods of field installation are discussed; one developed by ENPC in France uses a single tensiometer per hole, and the second technique, developed by Durham University in the UK, allows multiple tensiometers to be used at different depths within a single borehole. Continuous monitoring of pore water pressure has been carried out over several months and shows the responses to climatic events.

Ecological mitigation of hillslope instability: ten key issues facing researchers and practitioners

Abstract: Plants alter their environment in a number of ways. With correct management, plant communities can positively impact soil degradation processes such as surface erosion and shallow landslides. However, there are major gaps in our understanding of physical and ecological processes on hillslopes, and the application of research to restoration and engineering projects. To identify the key issues of concern to researchers and practitioners involved in designing and implementing projects to mitigate hillslope instability, we organized a discussion during the Third International Conference on Soil Bio- and Eco-Engineering: The Use of Vegetation to Improve Slope Stability, Vancouver, Canada, July 2012. The facilitators asked delegates to answer three questions: (i) what do practitioners need from science? (ii) what are some of the key knowledge gaps? (iii) what ideas do you have for future collaborative research projects between practitioners and researchers? From this discussion, ten key issues were identified, considered as the kernel of future studies concerning the impact of vegetation on slope stability and erosion processes. Each issue is described and a discussion at the end of this paper addresses how we can augment the use of ecological engineering techniques for mitigating slope instability. We show that through fundamental and applied research in related fields (e.g., soil formation and biogeochemistry, hydrology and microbial ecology), reliable data can be obtained for use by practitioners seeking adapted solutions for a given site. Through fieldwork, accessible databases, modelling and collaborative projects, awareness and acceptance of the use of plant material in slope restoration projects should increase significantly, particularly in the civil and geotechnical communities.

Modeling of Rainfall-Induced Shallow Landslides of the Flow-Type

Abstract: The paper deals with the modeling of failure and postfailure stage of shallow landslides of the flow-type that often affect natural shallow deposits of colluvial, weathered, and pyroclastic origin. The failure stage is frequently associated to rainfall that directly infiltrates the slope surface and to spring from the underlying bedrock. The postfailure stage is characterized by the sudden acceleration of the failed mass. The geomechanical modeling of both stages, based on site conditions and soil mechanical behavior, represents a fundamental issue to properly assess the failure conditions and recognize the potential for long travel distances of the failed soil masses. To this aim, in this paper, the current literature on the failure and postfailure stages of the shallow landslides of the flow-type is first reviewed. Then, an approach for their geomechanical modeling is proposed and three different modeling alternatives are presented. These models are then used to analyze, at different scales, a relevant case study of Southern Italy Sarno-Quindici event, May 4-5, 1998. Numerical analyses outline that both site conditions and hydraulic boundary conditions are among the key factors to evaluate the reliability of landslides of the flow-type. The potentialities and limitations of the available models are also evidenced as well as the perspectives related to the use of more advanced numerical models.