Documents published in Scipedia

• Site Exploration for Anchoring of Wave Energy Converters

  T. Evans*, T. Tran

  ISC2024.

  
  

  Abstract

  Wave energy converters (WECs), a form of marine hydrokinetic (MHK) energy device, transform the mechanical energy of water waves into electricity. They are typically held on station using anchoring systems embedded into the seafloor sediments (as opposed to, e.g., concrete gravity anchors). The design of WEC anchors is particularly challenging for two primary reasons: (1) WECs are often deployed in previously undeveloped areas of the ocean, so the engineering properties of the seabed are largely unknown; and (2) the economic margins on wave energy are quite thin, so heavily overdesigned anchor systems in response to data sparsity are not feasible. This paper describes the planning, execution, and outcomes from a dedicated in-situ testing campaign informed only by limited geophysical data a priori. A series of 22 cone penetration tests (CPTs) were performed at a 7-km2 site approximately 11 km off the United States’ west coast. Water depth was up to approximately 75 m and the target depth for the cone soundings was 10.5 m below the seafloor. Measurements indicated that much of the site subsurface consisted of dense sand and gravel, though tests identified an overlying softer layer in some parts of the site. A summary of lessons learned and recommendations for future explorations at similarly unexplored sites are provided.

  Abstract
  Wave energy converters (WECs), a form of marine hydrokinetic (MHK) energy device, transform the mechanical energy of water waves into electricity. They are typically held [...]

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• Continuous Medusa DMT tests in a very soft clay

  F. Danziger*, G. Jannuzzi, A. Pinheiro, J. Souza

  ISC2024.

  
  

  Abstract

  The dilatometer test (DMT) has been shown very useful in providing a number of geotechnical parameters, in different types of soils. The test is regularly carried out every 0.20 m, i.e., it is a discontinuous test. Therefore, its capability of detecting variations in the geotechnical profile is conditioned by the tests interval. The Medusa DMT, however, is able to obtain continuous measurements of the A-pressure reading, thus providing a much better picture of the soil stratigraphy. Medusa DMT tests have been carried out at Sarapuí II very soft clay deposit around Guanabara Bay, in Rio de Janeiro, and a detailed soil profile was obtained. A comparison was made with piezocone tests. The stratigraphy of the deposit obtained by both tests was almost the same.

  Abstract
  The dilatometer test (DMT) has been shown very useful in providing a number of geotechnical parameters, in different types of soils. The test is regularly carried out every [...]

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• Soil liquefaction assessment of Ecuadorian coastal region using SDMT test (Puerto Baquerizo site)

  C. Ramirez, F. Arias, D. Besenzon*, S. Amoroso, K. Chunga

  ISC2024.

  
  

  Abstract

  On March 18, 2023, a Mw6.6 earthquake hit the South Guayas coastal region (Ecuador), resulting in human fatalities and extensive structural damage. The event triggered widespread soil liquefaction evidences by significant volume of ejected material, which persisted several weeks following the event, marking the epicentral area prone to liquefaction. To assess the susceptibility to seismic-induced soil liquefaction, we performed one seismic dilatometer test (SDMT) in an area where the phenomenon clearly manifested. This study aims to evaluate and compare various established SDMT methods for predicting soil liquefaction potential under the specific 2023 seismic event. The findings are expected to enhance the understanding of liquefaction and contribute to improve seismic hazard assessment in areas along the Ecuadorian coast, which are often interested by earthquakes, as well as to the development of mitigation strategies in this earthquake prone coastal region.

  Abstract
  On March 18, 2023, a Mw6.6 earthquake hit the South Guayas coastal region (Ecuador), resulting in human fatalities and extensive structural damage. The event triggered widespread [...]

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• Characterisation of Carse Clays Using Seismic DMT

  A. O'Brien, I. Murray*

  ISC2024.

  
  

  Abstract

  The estuarine sediments around the head of the Forth estuary deposited during and after the Flandrian interglacial are an important, economically productive regional soil horizon in Scotland. The soil has been extensively studied locally (Hight et al., 1992) at the Bothkennar EPSRC site however, to the authors’ knowledge seismic dilatometer testing using Marchetti’s Medusa apparatus has never been used to characterise the material. Taking data from a number of sites and using an automated Medusa seismic dilatometer apparatus, a complementary contribution to the characterisation of the site which includes some comments on spatial variability of the material and other observations are presented.

  Abstract
  The estuarine sediments around the head of the Forth estuary deposited during and after the Flandrian interglacial are an important, economically productive regional soil [...]

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• Comparative Analysis of DMT, CPTt And DPH for Soil Characterization of Granular Rhine Soil

  J. Labenski, A. Poenaru*

  ISC2024.

  
  

  Abstract

  This paper presents the results of direct and indirect field investigations carried out as part of a detailed soil investigation of granular Rhine soil in Germany. After a brief overview of the project and geological conditions in the project area, the results of the field investigations are shown in a compressed and comprehensive manner. Focus of the presented results are the DMT, which are a novelty for projects in Germany. The presented results clearly indicate the challenges regarding the interpretation of the test results in the mainly dense to very dense sands and gravels, as especially the results of the DMT tend to scatter a lot. Despite the interpretation challenges, a comparative analysis of the CPT and DMT is carried out showing possible relations between dilatometer modulus Ed, friction angle DMT , corrected cone resistance qt and relative density ID. The relations are discussed, and limitations are presented. Afterwards, a strength-based correlation between CPT and DMT to determine the effective friction angle as a function of the cone resistance is presented indicating reasonable results for the investigated soils in the project area. The paper finishes with a discussion of limitations of the DMT and conclusions.

  Abstract
  This paper presents the results of direct and indirect field investigations carried out as part of a detailed soil investigation of granular Rhine soil in Germany. After a [...]

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• A novel strategy to digitalize, integrate and analyse data for the characterisation of landslides in turbiditic deposits

  N. Losacco*, V. Bufano, E. Tabak, F. Santaloia, F. Cotecchia

  ISC2024.

  
  

  Abstract

  A phenomenological interpretation of the slope factors and lanslide mechanism represents the first stage for the assessment of landslide hazard at the slope scale. This requires processing, analysing and integrating a large set of multidisciplinary and heterogeneous data, obtained through diverse activities, among which: geological and geomorphological studies, geotechnical investigations and monitoring, topographic and structural damage surveys. The integration of such a variety of multisource data, to build up a sound conceptual model of the slope, can be particularly challenging, especially in geohydromechanical contexts characterised by a great spatial variability of soil properties and complex hydraulic boundary conditions, such as in the case of slopes composed of turbiditic formations. This paper presents a new methodological approach for the study of landslide hazard at the slope scale, based on the combined use of an open-source GIS platform and an in-house developed dashboard for the interactive visualisation and analysis of geotechnical laboratory data. The details of the GIS project and the potentiality of the data-analysis dashboard are described, highlighting the interoperability between the two digital tools. The proposed methodology is applied to a pilot site, the Pianello area in Bovino, in the souhteastern Apennines, a widely investigated hillslope composed of tectonised clayey turbidite, hosting a complex basin of slow-moving landslides.

  Abstract
  A phenomenological interpretation of the slope factors and lanslide mechanism represents the first stage for the assessment of landslide hazard at the slope scale. This requires [...]

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• Dynamic properties of the Holocene age deposit in the Italian port of Ravenna

  M. Senigagliesi*, P. Alesiani, P. Ruggeri, V. Fruzzetti, G. Scarpelli

  ISC2024.

  
  

  Abstract

  Based on the collection of many data coming from a large survey carried out in the Ravenna Port channel, this paper focuses on the dynamic properties of the 30 m thick soil deposit whose poor geotechnical characteristics make the design of infrastructures in the area particularly challenging. The study included specific seismic in-situ investigations (e.g. Seismic CPTu and CH), laboratory tests on undisturbed bored samples (e.g. Resonant Column Test) and common in-situ testing (e.g. CPTu, DMT). The main objective is the estimate of the very small strain shear modulus and its decay with strain level (i.e. curves G0-gamma) for dynamic characterization. This is a fundamental aspect to consider for numerical modelling of geotechnical engineering problems considering soil-structure interaction under working loads and site response analysis. The availability of direct and indirect measurements of the dynamic soil properties allowed the comparison between the different estimates and an evaluation on the applicability of the correlations between the outcomes from possible in-situ investigations.

  Abstract
  Based on the collection of many data coming from a large survey carried out in the Ravenna Port channel, this paper focuses on the dynamic properties of the 30 m thick soil [...]

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• Effect of the fines content on the seismic response of a liquefiable deposit based on dilatometer tests

  G. Tropeano, A. Chiaradonna, P. Monaco*

  ISC2024.

  
  

  Abstract

  In the simplified methods for estimating the cyclic resistance ratio (CRR) based on the flat dilatometer test (DMT), the liquefaction triggering curve is defined as a function of the horizontal stress index. A DMT-based calibration of a simplified pore water pressure model for effective stress analyses has been also recently proposed by Chiaradonna et al. (2023), even though limited to an ideal clean sand. This paper aims to explore the effects of the fines content on the seismic response of a liquefiable site where the cyclic strength of the soils is estimated by dilatometer tests. This evaluation is firstly performed on an ideal one-dimensional soil column, where the percentage of fines content is parametrically changed. Then, the study is verified on a real case, by considering a well-investigated site located in the Emilia-Romagna plain (Italy), where widespread liquefaction occurred in the 2012 seismic sequence. Indeed, a comprehensive site characterization from previous in-situ and laboratory tests carried out by various research groups is available for sand, silty sand, and sandy silt deposits encountered in that area. The nonlinear dynamic analyses accounting for the fines content effect are compared with that obtained by adopting the calibration procedure based on laboratory tests. Guidelines and limitations of the proposed approach obtained from this study are useful in providing awareness to practitioners about the calibration strategies for dynamic analysis based on DMT-tests.

  Abstract
  In the simplified methods for estimating the cyclic resistance ratio (CRR) based on the flat dilatometer test (DMT), the liquefaction triggering curve is defined as a function [...]

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• Combined use of cptu-sdmt and geophysical test to assess liquefaction: case studies in Emilia-Romagna (Italy)

  S. Amoroso*, C. Comina, L. Minarelli, K. Rollins, S. Bignardi, F. Vagnon, F. Di Buccio

  ISC2024.

  
  

  Abstract

  The presence of a non-liquefiable crust overlying a liquefiable layer plays a significant role in determining the occurrence of liquefaction damage, as originally formulated by Ishihara in 1985. Following the 2010-2011 Canterbury seismic sequence (New Zealand), almost no foundation deformation occurred in areas characterized by soils susceptible to liquefaction overlaid by at least 3 m-thick intact crust. In contrast, the 2012 Emilia-Romagna earthquake (Italy) provided evidence of liquefaction in silty-sandy layers below 3 to 9 m-thick crusts. Therefore, Ishihara’s approach and the variety of liquefaction severity indices need to be further tested to assess to what extent they can be considered reliable predictors of performance. This study aims at better understanding the role of non-liquefiable crusts in preventing damage to buildings and infrastructures. In this respect, in situ and laboratory tests were conducted at selected sites in EmiliaRomagna. The results of two case studies in Mirandola (Modena, Italy), which share similar soil profiles but exhibited different liquefaction evidences following the 2012 seismic sequence, are presented. Comprehensive geotechnical and geophysical surveys were performed at both the sites, by means of piezocone tests, seismic dilatometer tests, boreholes, laboratory tests, electrical resistivity tomography and multichannel analysis of surface waves. These surveys document the geotechnical and geophysical properties of the 5 m-thick non-liquefied (or potentially non-liquefiable) crust and of the liquefied (or potentially liquefiable) silty-sandy deposits. This effort is aimed at understanding how the surface layer properties contributed to the different behavior observed at the two sites during the earthquake events.

  Abstract
  The presence of a non-liquefiable crust overlying a liquefiable layer plays a significant role in determining the occurrence of liquefaction damage, as originally formulated [...]

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• Comparison of Pore Pressure Parameters from Piezocone and Dilatometer

  J. Benoît*, B. Souza

  ISC2024.

  
  

  Abstract

  The Piezocone (CPTU) and the Marchetti Flat Plate Dilatometer (DMT) provide a number of empirical correlations for the purpose of soil identification. Each tool has defined a pore pressure parameter. For the piezocone, the parameter Bq ‘is based on the penetration pore pressures, the corrected tip resistance, the total overburden stress, and the existing hydrostatic pore pressure. This index has been used to characterize soil behavior rather than the actual soil type. For the dilatometer, the parameter Ud is based on the corrected pressures p0 and p2, calculated using the A and C readings and the existing hydrostatic pore pressure. This index can be combined with the material index ID to help with soil identification. Results from several test sites provide a promising direct correlation between Bq and UD, which can be used to enhance the identification of soil types by simply using the C-reading when performing DMT tests. Although the C-reading has been grossly ignored by users of the DMT, this new development will encourage measurement of this reading which provides similar trends to the pore pressures measured by the CPTU. The latest DMT equipment allows for the automatic measurement of the C-reading, which will assist in developing and enhancing existing correlations. This paper will present results at test sites located on opposite coasts of the USA. The trends of the Bq and UD indices are shown to be remarkably similar in all types of soils.

  Abstract
  The Piezocone (CPTU) and the Marchetti Flat Plate Dilatometer (DMT) provide a number of empirical correlations for the purpose of soil identification. Each tool has defined [...]

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