Documents published in Scipedia

• Early Screening for Improved Management of Geo-risks

  R. Eddies*, R. Wood, M. Staring

  ISC2024.

  
  

  Abstract

  Across several sectors including medicine and agriculture and the extractive industries, availability of early information from screening delivers disproportionate downstream benefit to key stakeholders. With the aim of reducing uncertainty to manage geo-risks in the subsurface, site characterisation for geotechnical engineering is mainly executed following a project owner’s final investment decision (FID) and continues to rely predominantly on conventional investigation techniques that inform both the geotechnical design and construction phases of infrastructure development. However, historical project performance of capital works developments tells us that geo-risks continue to play a role in unwanted engineering business outcomes in the form of schedule and cost overrun associated with earlier cost underestimation. Fundamentally, we recognise that the construction sector would benefit from earlier, faster, and better representation of the subsurface in the top 50 m to 100 m using techniques with a light footprint and low permitting requirements at the earliest stages of project development. We describe an example early-phase screening solution based on adapted ambient noise tomography. Screening at feasibility and planning phases can help to mitigate the impact of human bias arising from epistemic uncertainty in the subsurface and can improve early decision-making where the opportunity to influence project outcome is greatest and at lowest cost. Screening coupled with an optimised conventional intrusive investigation during the execution phase can complete the information set for full project design at considerably reduced levels of subsurface uncertainty leading to improved engineering business outcomes. The industry is encouraged to promptly incorporate the screening philosophy into feasibility and planning activities and into design codes for geotechnical design and construction.

  Abstract
  Across several sectors including medicine and agriculture and the extractive industries, availability of early information from screening delivers disproportionate downstream [...]

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• Interpretation of geotechnical data from an upstream dam for preparation of the site response analysis

  W. Durval Soares de Carvalho, T. Andrade, R. Viola, J. Ccotohuanca, M. Neto, D. Eloi*

  ISC2024.

  
  

  Abstract

  Despite seismic studies in Brazil not being common in the engineering practice as Brazil is a tectonically stable continental region, recent Brazilian regulations require seismic evaluation as supporting studies for decommission and decharacterization projects. Although there exist some critical issues such as limited laboratory data because of sampler processes related to the upstream raised tailings dams, standard tailings and soil foundation characterization, in addition to the field investigation including piezocone (CPTu), seismic piezocone (S-CPTu) and geophysical surveys are the main sources for supporting the characterization of the dynamic properties of the geostructures. This paper presents a brief discussion about the main aspects concerning to the site response analysis carried out for an upstream raised tailings dam (case study), located in Minas Gerais, Brazil. Frequency domain 1-D amplification analyses were conducted by relating local-like representative seismic records and dynamic natural characteristics of the soil profiles to evaluate the seismic response of the case study. Results showed that the maximum accelerations along the profiles are greatly influenced by the presence of the soft foundation tailings layers, and the level of amplification or attenuation is strongly influenced by the tailings layer thickness as well as the frequency content of the applied ground motions. The study pointed out that the site-specific response can support the definition of the appropriate seismic parameters to be used in engineering projects in Brazil.

  Abstract
  Despite seismic studies in Brazil not being common in the engineering practice as Brazil is a tectonically stable continental region, recent Brazilian regulations require [...]

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• New processing methodology of televiewer data for the definition of geotechnical and structural domains

  M. Heredia Bilbao, R. Sánchez Marín, R. Cano Martín, A. Deu Lozano, P. Martínez Diaz

  ISC2024.

  
  

  Abstract

  Six structural domains were defined using data from acoustic televiewers and oriented boreholes as part of the reopening of the old Aznalcóllar mining site in Sevilla, southern Spain, by Minera Los Frailes (MLF). Additionally, geotechnical subdomains were defined within each structural domain, classifying the subdomains based on geotechnical parameters obtained from the geotechnical logging of boreholes and through correlations. The methodology used to define the domains allows mine design and planning to be done with enough accuracy to determine the underground excavation needs and the systematic methodology. The main source of this new structural information was acoustic borehole image televiewers (ABI) and, on a much minor scale and as a complement for ABI data, oriented boreholes. This paper describes the methodology used for this definition, some of the challenges encountered during the investigation, the main results obtained and the utility of these defined structural domains in the development of the MLF mining site reopening. Additionally, a preliminary approach to an updated methodology in the definition of structural domains with the combination of televiewer data, both acoustic and optical, with data obtained from other downhole probes is also included.

  Abstract
  Six structural domains were defined using data from acoustic televiewers and oriented boreholes as part of the reopening of the old Aznalcóllar mining site in Sevilla, southern [...]

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• Multi-Method Geophysical Assessment of a Shallow Complex Landslide

  M. Rahimi, C. Wood*, S. Rahimi

  ISC2024.

  
  

  Abstract

  This study demonstrates the value of combining multiple non-invasive geophysical methods through a case study at a landslide along Highway 7 near Jasper, Arkansas, USA. Geophysical testing was conducted using Multichannel Analysis of Surface Waves (MASW), Horizontal to Vertical Spectral Ratio (HVSR), and Electrical Resistivity Tomography (ERT) along with select borings. Geophysical testing was aimed to provide a high-resolution and almost continuous image of subsurface conditions (including bedrock depth) for the slide area and to locate the groundwater table/highly saturated zones within the slide area which contribute to the slope movement. MASW revealed a highly variable depth to the weathered bedrock along the observed zone of displacement becoming shallower downslope. ERT detected saturated zones associated with observed seeps and springs in the area which were feeding water into the unstable zone. A low resistivity zone on the north side correlated to wet spots, while south of the highway saturation occurred near the deeper bedrock interface. Additionally, using a grid pattern HVSR approach, a high-resolution image of the shallow and complex bedrock topography was generated across the slide area providing valuable information for the repair design. Overall, the results of the combined geophysical approach provide a high-resolution image of landslide subsurface conditions which is critical for stability analyses and slope repair design. This integrated geophysical approach offers a more sustainable, rapid, and cost-effective solution for comprehensive landslide characterization and slope stability assessment when combined with conventional methods.

  Abstract
  This study demonstrates the value of combining multiple non-invasive geophysical methods through a case study at a landslide along Highway 7 near Jasper, Arkansas, USA. Geophysical [...]

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• Use of Macroseismic Intensity Data to Validate the Ground Motion Prediction Model in Albania

  A. Xhahysa*, M. Ceyhan, N. Kuka, E. Dushi, D. Koxhaj, K. Qoshi

  ISC2024.

  
  

  Abstract

  Macroseismic observations are a valuable tool, that can be used for the verification of site response and attenuation. Hence, in the framework of a bilateral project supported by Central European Investment Fund and with the extensive support of Global Earthquake Model Foundation to update the national seismic hazard model of Albania, intensity maps that contained more than 6000 macroseismic observations for 168 shallow (h

  Abstract
  Macroseismic observations are a valuable tool, that can be used for the verification of site response and attenuation. Hence, in the framework of a bilateral project supported [...]

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• In-Situ Cyclic Direct Shear Tests on Volcanic Soil in the Site of Landslide Due to Earthquake

  A. Sato*, H. Hashimoto, R. Kuwano

  ISC2024.

  
  

  Abstract

  Volcanic pumice soils are widely distributed in many countries. Mechanical properties of those need to be characterized since seismic ground motions can cause serious hazards such as large-scale slope failures and long-distance debris flows. Since volcanic pumice generally retains extremely high porosity and has a sensitive structure, the natural soil structure is easily broken during sampling or transportation. Therefore, it is preferable to conduct in-situ tests without disturbing the original structure of the soil. In this study, an in-situ direct shear test device was developed, and in-situ cyclic direct shear tests were performed on volcanic pumice (Ta-d). This pumice soil is considered to be the main cause of slope failure in Atsuma, Hokkaido, Japan, due to Easten Iburi earthquake in 2018. Laboratory direct shear tests were also conducted using undisturbed sample taken from the site. The results revealed that soil structure significantly affects shear strength. To evaluate the mechanical behavior of such sensitive soils, it is crucial to use specimens with as less disturbed specimens as possible. The newly developed in-situ direct shear test device was used to determine the cyclic shear strength of sensitive volcanic pumice soils.

  Abstract
  Volcanic pumice soils are widely distributed in many countries. Mechanical properties of those need to be characterized since seismic ground motions can cause serious hazards [...]

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• MASW Joint Analysis of Rayleigh and Love Waves for Site Characterization

  J. Hellín-Rodríguez, P. Martínez-Pagán*, I. Valverde-Palacios, A. García-Jerez, K. Suto, M. Martínez-Segura, J. Orta, J. Álvarez-Lozano

  ISC2024.

  
  

  Abstract

  The determination of reliable shear-wave velocity models using Multichannel Analysis of Surface Waves (MASW) has increased importantly for site characterisation studies due to their use in geotechnical studies and regulations. The standard MASW approach is commonly based on the analysis of vertical component of Rayleigh waves, which can result in inaccurate and potentially erroneous interpretations by personal bias. Thus, we present the joint analysis of different and independent multi-component data based on Rayleigh and Love waves to obtain 2D Vs sections for site characterization. Those seismic data were recorded using a landstreamer consisting of 8 triaxial 4.5Hz geophones. To generate Rayleigh waves, the blows were given vertically on a plate, and for the Love waves the blows were given laterally on a horizontal wooden beam. A joint analysis of Rayleigh and Love waves data was conducted on seismic data recorded from the metropolitan area of Granada city (Spain) to generate their dispersion curves. This new approach enabled a proper identification of fundamental- and higher-mode surface waves facilitating the reliable reconstruction of subsurface Vs profiles through a robust joint inversion process. The MASW 1D Vs versus depth models were corroborated at several test sites by the information obtained from boreholes. Thus, the main geological formations could be inferred from MASW 2D Vs sections down to a depth of 30 meters, as well as the Vs30 parameter to perform a reliable seismic microzonation of the study area. This methodology provides a very well constrained inversion procedure capable of providing a robust subsurface Vs model for site characterization.

  Abstract
  The determination of reliable shear-wave velocity models using Multichannel Analysis of Surface Waves (MASW) has increased importantly for site characterisation studies due [...]

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• Classification of an Exposed Mixed-Sediment Tidal Flat Using Synthetic Aperture Radar

  J. Paprocki*, N. Stark, F. Falcone, H. Graber

  ISC2024.

  
  

  Abstract

  Estuarine tidal flats represent a critical environment for maintaining healthy ecosystems. The geotechnical characterization of such environments is often challenging due to their soft nature and remote locations. Thus, the goal of this study is to explore the use of remotely sensed, high resolution (pixel resolution of ~0.5 m) synthetic aperture radar (SAR) data for characterizing these sediments. Towards this goal, the variability of sediment properties (median gain size, moisture content, fines content, and classification following the Unified Soil Classification System (USCS) were documented for a mixed tidal flat located on the Great Bay Esturay in New Hampshire, USA. A sediment classification scheme based on SAR, originally proposed by Gade et al. (2008), which utilizes the correlation length to characterize sediments based on the percentage of particles

  Abstract
  Estuarine tidal flats represent a critical environment for maintaining healthy ecosystems. The geotechnical characterization of such environments is often challenging due [...]

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• 3D Resistivity Survey of a Weathering Profile of Metamorphic Rocks in State of Pernambuco, Brazil

  R. Coutinho*, C. Bortolozo, M. Andrade, F. Silva

  ISC2024.

  
  

  Abstract

  This paper aims to study a weathering profile of crystalline rocks in the City of Camaragibe, State of Pernambuco, Brazil. For this purpose, a survey using electroresistivity was conducted. A regular mesh was performed aiming at 3D acquisition. The target area of the survey has 3 meters of depth (the Data Collection Platform, abbreviated as PCD) responsible for recording soil moisture information. An auger soil sampler was also made reaching a depth of 3 meters to describe and identify the substrate. The main objectives of the paper are to determine the geoelectrical characteristics of the materials and relate them to the strata previously identified and the soil moisture profiles. A goal was also to calculate moisture from the resistivity model and compare the results with those obtained by the PCD. The results allowed the creation of 3D geo-electric models, extending to a depth of 8 meters. It was also possible to create a 3D soil moisture model. It was possible to make a correlation between the geoelectric horizons and the layers of the rock alteration profile. The humidity results obtained by PCD and the resistivity model were examined, indicating favorable prospects for applying the method.

  Abstract
  This paper aims to study a weathering profile of crystalline rocks in the City of Camaragibe, State of Pernambuco, Brazil. For this purpose, a survey using electroresistivity [...]

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• Muon Tomography for Mapping and Monitoring Tailings Storage Facilities

  M. McLean, F. Scutti, R. Seikel, S. Krishnan, C. Webster, S. Collins, C. Goss, S. Palanisamy, P. Panchal, J. Donovan, A. Duffy, A. Christensen*

  ISC2024.

  
  

  Abstract

  Tailings storage facilities pose an increasingly significant global challenge for mining companies. Given that tailings, the by-products of mine processing plants, demand meticulous management due to the potential hazards associated with storage facility failures, continuous attention is imperative. The repercussions of such incidents can lead to profound and enduring environmental damage in downstream regions. Therefore, consistently monitoring the structural stability of these facilities is paramount to ensure the safety and sustainability of both active mining sites and legacy mines. This paper introduces an innovative approach using muon tomography to analyze the internal density structures of tailings dams. The research, conducted at the BHP Prominent Hill Mine site in South Australia, presents a pioneering method and technology for examining the internal density distribution of tailings storage facilities using muons. Muons, being a natural source of radiation capable of generating X-ray-like scans of large structures, offer a distinctive opportunity to gain insights into the inner structure of tailings storage facilities. Moreover, this technology holds the potential to serve as a foundational platform for future research in the development of early warning systems for detecting structural changes.

  Abstract
  Tailings storage facilities pose an increasingly significant global challenge for mining companies. Given that tailings, the by-products of mine processing plants, demand [...]

  • 108
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