Documents published in Scipedia

• Identification of random field for ground stiffness by data assimilation based on surface wave method and sounding tests

  S. Nishimura*, Y. Ren, T. Shibata, T. Shuku

  ISC2024.

  
  

  Abstract

  The surface wave method (SWM) and the screw weight sounding (SWS) are employed as a geophysical exploration method and a sounding test, respectively to identify the spatial distribution of the stiffness of an earth-fill dam in the present study. The ensemble Kalman filter (EnKF) is used as a data assimilation technique. It can estimate the spatial distribution of the Young’s modulus as the stiffness of an earth-fill dam by assimilating the travel time to the first arrival of the surface waves. By the ensemble data assimilation, the measured data from the SWM is applied to simultaneously estimate the Young's modulus and evaluate the uncertainties. The SWS results are employed as the prior information to generate the initial ensemble through the sequential Gaussian simulation (sGs). Proposed method has been applied to the actual data of the SWM and the SWS measured at an earth-fill dam site. Consequently, it has been clarified the proposed approach could identify the appropriate random field of Young's modulus.

  Abstract
  The surface wave method (SWM) and the screw weight sounding (SWS) are employed as a geophysical exploration method and a sounding test, respectively to identify the spatial [...]

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• Toward probabilistic ground models for time and cost estimation of tunnel projects

  J. Spross*, I. Papaioannou, J. Grasmick

  ISC2024.

  
  

  Abstract

  The construction time and cost of a rock tunnel project are highly dependent on the rock mass quality and encountered ground behaviour. In most rock tunnel projects, the knowledge about the ground conditions along the tunnel is limited, making it difficult to predict accurately the construction time and cost. The KTH model takes a probabilistic approach to address this problem; however, it does not account for the spatial variability of the ground conditions. This paper investigates an alternative probabilistic ground model to be used within the KTH model that enables accounting for the spatial variability through Markov random field theory. The new ground model employs a parametric approach to describe the properties of the Markov field, hence, enabling the simulation of the ground conditions with limited data, but does not consider the epistemic uncertainty in the model parameters. This will be the addressed in future research.

  Abstract
  The construction time and cost of a rock tunnel project are highly dependent on the rock mass quality and encountered ground behaviour. In most rock tunnel projects, the knowledge [...]

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• Data-Driven Simulation of Multivariate Cross-Correlated Geotechnical Random Fields from Sparse Measurements

  Z. Guan, Y. Wang*

  ISC2024.

  
  

  Abstract

  It is widely acknowledged that many geotechnical properties are correlated over space and/or time. Consequently, crosscorrelated random fields play a pivotal role in geotechnical reliability analysis for properly modeling both the auto- and cross-correlation structures of correlated geotechnical properties. Existing methods for simulating cross-correlated random fields typically require precise knowledge of random field parameters as input. However, in a typical site investigation program, engineering constraints such as limited time, budget, and space often lead to sparse measurements of geotechnical properties. Estimating reliable random field parameters, particularly the auto-correlation and crosscorrelation structures of a two-dimensional (2D) cross-correlated random field, from such sparse data is a notorious challenge. To address this issue, this study introduces a 2D cross-correlated random field generator that can directly simulate 2D multivariate cross-correlated geotechnical random field samples (RFSs) from sparsely measured data points. This generator leverages the method developed by Guan and Wang (2023), which employs a joint sparse representation to simultaneously exploit auto- and cross-correlation structures of various spatial/temporal quantities directly from sparse measurements. The effectiveness of the proposed generator is demonstrated using real geotechnical properties data. The results demonstrate that RFSs generated using this method from sparse measurements accurately capture the spatial auto- and cross-correlation structures of different geotechnical properties.

  Abstract
  It is widely acknowledged that many geotechnical properties are correlated over space and/or time. Consequently, crosscorrelated random fields play a pivotal role in geotechnical [...]

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• Stratification identification and prediction of missing CPT data by Mixture of Gaussian Processes

  M. Durmaz*, A. van den Eijnden, M. Hicks

  ISC2024.

  
  

  Abstract

  Stratification identification and spatial interpolation play a fundamental role in geotechnical site characterization. A unified approach is needed to perform these two tasks simultaneously to reduce overall uncertainty in site characterization. This paper explores the applicability of the Mixture of Gaussian Processes (MoGP) to address this gap, with a specific focus on characterizing and completing missing CPT data. The investigation encompasses both synthetic and real-world field CPT datasets and includes a comparison of the MoGP's interpolation accuracy with the use of a single GP for entire datasets. Additionally, the study examines the sensitivity of the model's performance with respect to the number of training data points. Although the interpolation performance of the MoGP model is promising with synthetic data, limitations appear in its application to real-site CPT data.

  Abstract
  Stratification identification and spatial interpolation play a fundamental role in geotechnical site characterization. A unified approach is needed to perform these two tasks [...]

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• SDMT VS profiles in heterogeneous granular soil deposits

  F. Totani*, V. Tomei

  ISC2024.

  
  

  Abstract

  Many urbanized areas of the Apennines, in Italy, have complex soil stratifications. A typical example is the historical center of L'Aquila and its outskirts, founded on layers of significantly heterogeneity and struck by a strong earthquake in 2009. Under these conditions, shear wave velocity profiles (VS) obtained from in-situ measurements using SDMT techniques allow reliable analyses of local seismic response. In the soil of L'Aquila, the use of SDMT tests in sand-filled boreholes, following the procedure described by Totani et al. (2009), allowed VS to be measured at considerable depths. This article presents the results of local seismic response analyses conducted to characterize the soil foundation of the hospital complex and adjacent university buildings in L’Aquila before their seismic retrofitting. The authors developed a soil model based on the Vs profiles retrieved from the SDMT tests. This approach provided a detailed understanding of the soil seismic behaviour, essential for the proper characterization of seismic action and consequently, the design of seismic interventions. The study emphasises the importance of accurate soil characterisation prior to seismic upgrades especially in deposits where there are multiple shear wave velocity inversions. The seismic demand coming from the Italian Building Code of 2018, based on the so-called soil categories from equivalent velocity of shear wave, was compared to the results of the local seismic response analysis conducted by using the real Vs profiles from SDMT, which are extended to a much greater depths than those generally required by the regulations.

  Abstract
  Many urbanized areas of the Apennines, in Italy, have complex soil stratifications. A typical example is the historical center of L'Aquila and its outskirts, founded on layers [...]

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• Compacted Landfill Quality Based on DMT

  A. Penna*, A. Macedo, G. Freitas, L. Melo

  ISC2024.

  
  

  Abstract

  For the last 25 years we have been using DMT tests to check the quality of landfill compaction. In several situations of large areas subject to earthmoving, significant pathologies were observed associated with the occurrence of settlements, determined by poor compaction of landfills. These settlements affect the internal floors of buildings, external floors, and sometimes the foundations also. With the intense use of the DMT test as an usual geotechnical investigation practice, it was possible to group the results of these tests, separating them into cases of good, average, and bad behavior. With these systematic observations, it was possible to adapt the traditional graphical representation proposed by Silvano Marchetti and David Crapps, relating the material index "Id" with the dilatometer modulus "Ed", creating regions that represent well-compacted landfills, those with medium compaction and poorly compacted landfills. This system makes it easy to predict the settlement behavior of compacted landfills and represents an appropriate method for checking the quality of compaction.

  Abstract
  For the last 25 years we have been using DMT tests to check the quality of landfill compaction. In several situations of large areas subject to earthmoving, significant pathologies [...]

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• 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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