Subsoil Model Research Articles

Are the Italian microzonation level 2 abacuses applicable in the Friuli Venezia Giulia (Italy) plain? Comparison between the national abacuses and the numerically simulated amplification factors and between the derived elastic response spectra

Seismic shaking of an area is strongly affected by the local geology. The so-called local site effects must be considered for the estimation of seismic effects on structures and urban planning. Thus, the seismic microzonation is the process aimed at identifying and mapping the subsoil local response in a given area, usually at urban/municipality scale and in terms of ground shaking parameters and susceptibility to ground instabilities. In Italy, for areas that can be schematised as a 1D subsoil model (e.g. alluvial plain), a simplified approach is proposed to quantify the seismic amplification (amplification factor, AF). This approach consists of tables of correspondences, called seismic abacuses, available for the whole national area as well as for some regional territories, and derived for simplified subsoil models. In this work, the results of the comparison between the AF values retrieved from national abacuses applied in the Friuli Venezia Giulia (Italy) plain municipalities and those from 1D numerical simulations are presented. In general, the abacuses underestimate the local seismic site effects a part for sites with a shallow bedrock. No correlations/trends were identified between the AF derived from abacuses and those from numerical simulations. Moreover, considering the elastic acceleration response spectra, it emerges that in the 49.5% of the FVG analysed sites the abacuses approach, even though it underestimates the real seismic response, is a more suitable approximation compared to the soil class simplified approach proposed by the Italian regulation. Finally, what emerges is that the limit of 30 m, as indicated in the Italian regulation, to consider a deep or shallow bedrock seams underestimated, and the AFs are not correlated with the seismic bedrock depth when it is higher than 100 m.

Engineering Geological and Geophysical Investigations to Characterise the Unstable Rock Slope of the Sopu Promontory (Gozo, Malta)

Different engineering geological and geophysical investigations were performed at the Sopu promontory in the island of Gozo (Malta), involved in an impressive lateral spreading process due to the superimposition of a stiff limestone (ULC) on a ductile clay (BC). The applied techniques include: traditional geological and engineering geological surveys, unmanned aerial vehicles (UAV) survey, electrical resistivity tomography (ERT) survey, ground-penetrating radar (GPR) investigations, single-station seismic ambient noise measurements, and array seismic ambient noise measurements. The integration of the obtained results allowed us to reconstruct a subsoil model of the promontory that includes features related to the local geology of the slope and to the landslide process, as well as to define a conceptual model that describes the main evolution phases of the expansion process. The presence of back-tilted rock blocks with no features of polarization of Rayleigh waves evidenced the different failure mechanism of the rigid UCL plateau at the Sopu promontory with respect to the Selmun promontory, located in the close island of Malta, where the lateral spreading due to the same geological setting tends to produce unstable rock blocks with a toppling mechanism. This result encourages further future observations and analyses of this topic.

Reconstruction of a subsoil model for local seismic response evaluation through experimental and numerical methods: The case of the Wellington CBD, New Zealand

Defining a reliable subsoil model is one of the most crucial points in the evaluation of the local seismic response, especially when the study area presents a complex geological setting. Performing a large number of investigations during and subsequently a seismic crisis (following a strong earthquake) is useful for collecting valuable data. By applying a multidisciplinary approach, these data can be used for constraining and test the model, as well as for directly evaluating the effects of strong earthquakes on the environment and the distribution of structural damages in heavily populated areas. In the present study, through a new multidisciplinary experimental–numerical approach, we investigated the role of local site conditions on the damage observed in the Central Business District (CBD) of Wellington (New Zealand) after the 2016 M7.8 Kaikōura event.Numerical 1D/2D site response analyses were carried out to explore the hypothesis of damage exacerbation due to basin effects. Our numerical models were then validated by comparing the corresponding numerical amplification functions with those derived from the application of the standard spectral ratio technique to a large accelerogram dataset. This dataset was obtained by GeoNet stations deployed in the study area, including those operative during the 2016 M7.8 Kaikōura event. Differences in ground motion for near- and far-field events were highlighted.Our results show that the site response in the Wellington CBD was controlled by complex 2D/3D valley effects (mainly edge effects), which were related to the local buried geomorphology. Overall, these findings suggest that the type and location of an earthquake influence the maximum distance at which 2D effects (generated at the basin edge) are still detectable. Comparing our dataset with those from other published studies would be useful for clarifying the factors leading to an exacerbation of the seismic response in alluvial basins. This study has also possible implications for seismic hazard mitigation in cities built on such basins. We conclude that robust numerical 2D models can provide and capture notable characteristics of the ground motion associated with basin effects. These characteristics are fundamental for understanding basin effects and should be considered when formulating building regulations.

The influence of the variability of the support of the mortar base plate on the quality of the results obtained in the process of its numerical design

Due to the high costs associated with the purchase of ammunition and firing in certified training ground centers, tests of retaining plate deformations are increasingly replaced by computer simulations using numerical models. Computer programs usually use a single-parameter subsoil model (Winkler-Zimmermann) for calculations, which requires providing the subgrade susceptibility coefficient. The subgrade compliance coefficient is intended to determine the mutual reaction of the subgrade and the structure due to the pressure exerted on the soil by the retaining slab, which settles. When designing slabs in computer programs, it is assumed that the substrate compliance coefficient is constant. Determining the impact of the soil on the retaining slab is important when analyzing its deformations. The subject of the work was the analysis of the influence of ground support on the results obtained during modeling of the retaining slab. In order to obtain data for FEM analysis and validation, the actual strains occurring on the thrust plate were measured using strain gauge rosettes. The plate deformations were measured during field shooting tests. In order to vary the influence of supporting the slab on the ground and obtain reliable stress values on the slab surface, a method of successive iterations was proposed. Calculations are performed using this method until the error is smaller than the assumed one.

Extended Tromograph Surveys for a Full Experimental Characterisation of the San Giorgio Cathedral in Ragusa (Italy).

Geophysical surveys are widely used to reconstruct subsoil seismo-stratigraphic structures with a non-invasive approach. In this study the geophysical surveys were carried out with the aim to characterise the San Giorgio Cathedral in Ragusa (Italy) and the area on which it is built from a dynamic point of view. A 3D subsoil model was realised through the integration of two active (i.e., seismic tomography and multichannel analysis of surface waves) and one passive seismic technique (horizontal to vertical spatial ratio). The instrumentation used for the latter method consists of a tromograph (Tromino®), which is also employed for the characterisation of the building, focusing on the façade and the dome, by means of an ambient vibration test, processed through the standard spectral ratio and frequency domain decomposition methods. Integration of the 3D model, showing the distribution of areas with different physicomechanical characteristics, enables identifying anomalies that are likely attributable to the remains of the ancient Byzantine church of San Nicola. Four lower modes mainly involving the two investigated macroelements are identified. The experimental results outline the advantages of the use of the tromograph both for soil and structural characterisation, especially for massive masonry buildings located in areas with high seismic hazard.

3D FEM Analysis of the Subsoil-Building Interaction

This paper presents the process of advanced numerical analysis of interaction between a building and the subsoil. The analysis covered a wide range of work for both computing and research. As part of the research work, field and laboratory subsoil tests were carried out, as well as geodetic measurements of building settlement and measurements of natural vibrations of an object. The computational work included the analysis of a total of 47 FEM models. The subsoil was described using the Modified Cam-Clay model, with parameters determined using field CPT and SDMT tests, as well as triaxial and edometric laboratory tests. Parts with geodetic benchmarks were separated from the building model, and then multi-variant calculations were made on smaller, partial models with parameters obtained from various methods. Calibration of the main models was performed using 8 partial models for which calculations were carried out in 4–5 variants of parameters. This gave a total of 38 partial models. Then, calculations were carried out on the full model of the building with subsoil. At each stage, the results of vertical displacements were compared to the geodetic values. The measured settlement of the real building in the time from the construction of the underground story to its use for the period of 1 year, was from 2.3 mm to 7.8 mm. The settlement from FEM calculations of small calibration models for the same benchmarks was from 2.0 mm to 9.8 mm with parameters derived from CPT tests and from 1.8 to 7.3 mm for parameters derived from SDMT. For the full building model, settlement from FEM calculations ranged from 2.2 to 8.8 for the variant with a simplified subsoil model, and from 3.7 to 10.5 for the model taking into account the inhomogeneity of the subsoil. As a result, it was found that the displacements from the numerical analysis were convergent with the geodetic values. Detailed numerical analyses also allowed to detect the deviations of the segments from the vertical and to indicate potential damage to the structure. It was also indicated how the work of the subsoil influences the stress distribution in selected structural elements. Behaviour of the subsoil has an impact on the behaviour of the building and its deformations, as well as on the distribution of stresses in the structural elements, and, as a result, on the change in the distribution of internal forces in the structure.

Estimation of subsoil parameters and settlement of foundation for a project in Kolkata based on CPT, DMT.

In this study, focus is given on a selected project site. This site is located at Jadavpur University, Saltlake Campus, area situated in Kolkata city of India. The subject site comprises building structures with isolated footing. The soil investigation was carried out by two different approaches i.e., cone penetration test (CPT), and Marchetti Flat Dilatometer Test (DMT). The study describes a comparative study of undrained cohesion (Cu), angle of internal friction (Φ), constrain modulus (M) measured from CPT and DMT. Apart from that settlement analysis also been done for two different sizes of foundation e.g. (3M X 1M), (4M X 1M) by DMT Settlement software and PLAXIS2D. For providing the subsoil model for the investigation area, all the DMT and CPT results were compared with each other

Digital design and stability simulation for large underground powerhouse caverns with parametric model based on BIM-based framework

Large infrastructures involving underground engineering like the underground powerhouse caverns constitute multi-medium, complicated and interaction systems, which require geotechnical data management, parametric model construction, optimal design alternatives, and real-time safety assessment. However, even though the data needed for numerical analysis is recorded in the Building Information Modeling (BIM) parametric models, the transformation of geometric characteristics between BIM and numerical models is cumbersome. Therefore, an automatic numerical simulation analysis framework was proposed, which can not only convert 3D parametric structural geometry model by indirect method, but also realize automatic pre-treatment and analysis, such as mechanical properties definition, boundary conditions assignment and mesh generation. In this study, the digital model of underground powerhouse caverns accompanying with cavern support system could be constructed automatically via secondary development on CATIA software. Reorganized borehole logs at geological profiles accompanying with topographic-geologic map are also used to define the 3D subsoil model. Python codes are programmed for pre-treatment of numerical model to enhance the calculation efficiency and alleviate the manual interventions by linking differ-format data files. Furthermore, a case study of Suki Kinari underground powerhouse caverns was exemplified the advantages of this framework in terms of modeling and pre-treatment efficiency, and error-free geometric information translation. The proposed framework provides a fundamental process for automatic design-to-analysis, hence mitigates user intervention and error-free structural calculation for design-making.

Case Studies and Challenges of Implementing Geotechnical Building Information Modelling in Malaysia

Unforeseen ground conditions are some of the main contributors to construction cost over-runs and late completion. Recent research trends have witnessed the scopes of building information modeling (BIM) technology being extended to subsoil and substructure constructions, or simply known as geotechnical BIM. This paper aimed to explore the procedures of developing 3D subsoil models through two case studies in Malaysia. The geotechnical BIM processes were performed by commercial software, AutoCAD Civil 3D 2017, with the extension of the Geotechnical Module. The modeling procedures can be divided into three main stages, namely data collection, data interpretation, and data visualization. The subsoil models were successfully developed at different levels of detailing to serve for different applications. The results showed that the 3D subsoil modeling required huge modeling and computational efforts, particularly when dealing with tropical residual soil profiles in Malaysia that are highly intricate. Thus, an adequate soil strata generalization was required to simplify the generated subsoil model. Data collection and management was identified as one of the main challenges of promoting geotechnical BIM in Malaysia at a macro-scale. Despite the challenges, successful implementation of the geotechnical building information in the present case studies were proved to be capable of promoting interoperability of soil data, which is an essential element in sustainable construction.

The potential of spatial statistics for the reconstruction of a subsoil model: A case study for the Firenze-Prato-Pistoia Basin, Central Italy

A reliable subsoil model represents the first step in assessing potential geological hazards and adopting proper mitigation measures accordingly. However, one of the main difficulties related to the definition of such models concerns the extrapolation of single-point data over wide, uninvestigated areas. For this reason, in this work, we reconstruct a subsoil model within an alluvial basin through a methodology specifically based on spatial-statistical analyses of geophysical in situ point measurements. In particular, measurements of ambient noise were analysed and extrapolated to obtain a spatially continuous distribution of fundamental resonance frequency (f0) over the entire basin. Local portions of the basin were then defined according to a specific relationship between f0 and the minimum distance from the bedrock outcrops (MDBO). This analysis revealed how the position of the identified clusters is consistent with the asymmetric geometry of the basin. The resulting simplified subsoil model was then validated through additional experimental measurements of ambient noise to evaluate the reliability of the proposed methodology. As the test site, we selected the Firenze-Prato-Pistoia Basin (Tuscany region, central Italy), where more than two hundred homogeneously distributed noise measurements were collected from previous seismic microzonation investigations.

Combining single-station microtremor and gravity surveys for deep stratigraphic mapping

Any stratigraphic reconstruction by means of surface geophysical methods is affected by the nonuniqueness of data inversion and by the resolution-depth trade-off. The combination of different geophysical techniques can reduce the number of degrees of freedom of the problem. We have focused on two low-impact single-station geophysical techniques: microtremor and gravity. These have been used by previous authors for stratigraphic mapping only by comparing the results independently. We suggest a procedure to combine microtremor and gravity data into a unique subsoil model and explore to what extent their combined use can overcome their individual weaknesses and constrain the final result. We apply the procedure to the Bolzano sedimentary basin, Northern Italy, to derive a 3D bedrock model of the basin. We use microtremor data to map the ground resonance frequencies and derive an initial 3D bedrock depth model by assuming a [Formula: see text] profile for the sediment fill. Then, we define a density model for rock and sediments and perform 3D gravity forward modeling. We then perturb the [Formula: see text] and density models and find the parameters that best fit the observed gravity anomalies. Data uncertainties are examined to explore the significance of the results. Joint use of the two techniques successfully helps interpret the stratigraphic model: Ground resonance frequencies guarantee the spatial resolution of the bedrock geometry model, whereas gravity data help constrain the frequency to depth conversion.

Reconstruction of a Reference Subsoil Model for the Seismic Microzonation of Gori (Georgia): A Procedure Based on Principal Component Analysis (PCA)

ABSTRACTThis article focuses on the full exploitation of geological and economically viable geophysical surveys for the seismic characterization of the shallow subsoil in the frame of microzonation studies in urban areas where economic resources for detailed seismic response analyses are scarce. In these conditions, the outcomes of inexpensive geophysical surveys (e.g., based on ambient vibration monitoring or surface-wave prospecting) must be fully exploited. To reduce the uncertainties related to these kinds of procedures, their joint interpretation in the light of geological evidence is mandatory. To this purpose, we propose the application of principal component analysis to combine the results of distributed single-station ambient vibration measurements (horizontal-to-vertical spectral ratio [HVSR] technique) to provide a preliminary zonation of the study area. The zones identified in this way are then characterized by considering the available geognostic boreholes, VS profiles deduced by the joint inversion of HVSR curves, and available Rayleigh-wave dispersion curves deduced from active seismic prospecting (multichannel analysis of surface-waves technique). The final outcome allows the definition of a preliminary seismic model of the study area, which is also constrained by the available geological data deduced from on-purpose surveys. The proposed approach has been applied to the city of Gori (Georgia). The proposed approach allowed a reliable assessment of buried geometries, geological domains, and the distribution of lithofacies, which can control the local seismic response. In detail, the major role of paleovalley infills and interfluve domains has been enlightened by adding in evidence concerning the peculiar stratigraphic relationships and buried morphologies, which may determine 1D and 2D resonance effects.

Towards network assessment of permanent railway track deformation

The permanent railway track deformation caused by regular train traffic is important for infrastructure managers and railway contractors, as it determines the railway track quality. Although several successful approaches have been made to address the topic of the permanent railway track deformation, these have only been applied at specific locations, and have not yet been successfully applied at a network level. This paper presents a methodology that can be applied at the network level, by making use of a stochastic subsoil model to characterise the subsoil uncertainty and variability along the railway line, and by combining it with a dynamic train-track model and a cumulative cyclic deformation model. This methodology is illustrated by analysing a railway track section of 9 km in the Netherlands. The effects of the train service, such as train speed and axle loads, on the permanent deformation of the track are quantified. The proposed methodology has been partially validated against results of the dynamic stiffness obtained during the passage of a measurement train. The results illustrate the added value of this methodology for infrastructure managers and railway contractors as it allows for the quantification, at network level, of the consequences of train service changes for the future state of the railway network.

Seismic amplification maps of Italy based on site-specific microzonation dataset and one-dimensional numerical approach

Prediction of surface ground motion based on advanced approaches is a non-trivial task at large area. In fact, advanced approaches require a detailed geological and geotechnical subsoil model based on geological, physical and mechanical properties retrieved from in situ investigations and laboratory data, and to perform time consuming numerical simulation of the seismic site response. Bearing in mind that there is a lack of available site investigations and laboratory data at large area, simplified methods based on “soft data” are often adopted. On this regard, a methodology to perform seismic site response analyses at national scale is proposed in this paper, based on the following assumptions: 1) homogeneous areas were identified at national scale based both on morpho-geological and lithological properties, in order to classify and analyse site-data archived in the Italian database of seismic microzonation studies; 2) geotechnical subsoil one-dimensional models of the Italian site conditions were defined according to site-data; 3) in accordance with the reference seismic hazard levels, pseudo-acceleration response spectra were selected as input motions for numerical simulations.About thirty million numerical simulations of seismic site response were performed, and national maps of seismic shaking amplification factors were produced in terms of ratio of response spectra referred to three intervals of period. This estimation of surface ground motion based on the proposed procedure is a supporting tool for large area territorial and emergency planning.

Evaluation of site effects at Amatrice (central Italy) after the August 24th, 2016, Mw 6.0 earthquake

This work presents results obtained from numerical site response analyses in the area of Amatrice (central Italy) with a main focus on the town's historical centre, where a more significant differential damage was observed after the August 24th, 2016, Mw 6.0 earthquake and the following aftershocks. Geological field investigations were performed and used to define a series of detailed geological cross-sections across the hill, which is the distinctive morphological feature of the town. Following insights from geological cartography, four continuous coring boreholes were drilled to obtain a new refined subsoil model of the area at depth; three of these boreholes were used to perform down-hole tests to constrain the shear-wave velocity (Vs) of the geological units. The subsoil model also included the results of the available seismic arrays and 80 single station ambient vibration stations, which allowed the calibration of the dynamic model, enhancing its robustness. The analyses allowed for a comparison of available empirical amplification functions and the simulated transfer functions of this study. Empirical transfer functions are represented in this case through the available Standard Spectral Ratio curves computed from recorded earthquakes of the 2016–2017 seismic sequence. They show a broad peak centred between 2 and 3 Hz, corresponding to the predominant frequencies of the hill, and a flat response outside the hill, in good agreement with the modelled transfer functions determined following two-dimensional (2D) approach. Conversely, one-dimensional (1D) transfer functions could not describe the amplification in the same range, confirming the evidence of overlapping topographic and stratigraphic effects. In the historical part of the town, only ambient vibration data were available. Notwithstanding that only a comparison of numerical resonance frequencies with the experimental frequencies highlighted using the horizontal-to-vertical spectral ratio (HVSR) method on ambient vibration data is possible in this case, reasonable agreements were found in the considered frequency range 1–10 Hz. In-depth characterisation of the subsoil of the historical centre of Amatrice provided a useful tool for challenging the problem of the realistic ground motion estimates, by evaluating possible local effects which could enhance or modify the input motion.

Study of Input Parameters of Layered Half-Space used for Soil Modelling

This article deals with a problem of soil modeling. That is a necessary part of foundation modeling.The soil modeling can directly influent the resulting deformation of the foundations and therefore deformationof the whole building. The accurate procedure that can simulate the foundation-soil interaction is still unknown.A greater understanding of the issue through experiments and numerical modeling is important for a goodapplication and proper use in practice. To improve this understanding an experimental test of a concrete slabwas performed on special testing equipment. The experiment is complemented by numerical modeling.Numerical models are created in the Ansys software. The article features three cube models and a half-spheremodel. Deformations on all featured models are discussed and compared to the experimental values andsimplified hand calculation. The subsoil model is based on the Boussinesq half-space theory. The soil section isassumed homogeneous and layered. The size of models is assumed as a changing parameter from 10 m to 30 m.A recommended model size was evaluated from the parametric study as a match of deformation from modelsand the experiment. This computed model size is compared with an affected depth described by the standardČSN 731001. Computation was performed using supercomputer Anselm in the National SupercomputingCenter IT4Innovations in the VSB-Technical University of Ostrava.

Estimating dissolved carbon concentrations in global soils: a global database and model

Dissolved carbon (C) leaching in and from soils plays an important role in C transport along the terrestrial-aquatic continuum. However, a global overview and analysis of dissolved carbon in soil solutions, covering a wide range of vegetation types and climates, is lacking. We compiled a global database on annual average dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in soil solutions, including potential governing factors, with 762 entries from 351 different sites covering a range of climate zones, land cover types and soil classes. Using this database we develop regression models to calculate topsoil concentrations, and concentrations versus depth in the subsoil at the global scale. For DIC, the lack of a proportional globally distributed cover inhibits analysis on a global scale. For DOC, annual average concentrations range from 1.7 to 88.3 (median = 25.27) mg C/L for topsoils (n = 255) and from 0.42 to 372.1 (median = 5.50) mg C/L for subsoils (n = 285, excluding lab incubations). Highest topsoil values occur in forests of cooler, humid zones. In topsoils, multiple regression showed that precipitation is the most significant factor. Our global topsoil DOC model ({mathrm{R}}^{2}=0.36) uses precipitation, soil class, climate zone and land cover type as model factors. Our global subsoil model describes DOC concentrations vs. depth for different USDA soil classes (overall ({mathrm{R}}^{2}=0.45). Highest subsoil DOC concentrations are calculated for Histosols.

The seismic microzonation study of Pescara del Tronto (Central Italy) during and after the Central Italy earthquake sequence.

Site effects in consequence of the 2016–2018 Central Italy seismic sequence “marked the fate” of many villages located close to the epicenters along the Apennine chain. Pescara del Tronto, a small settlement located on a mountain slope in the municipality of Arquata del Tronto, (AP) is very representative of such territories since, early after the onset of the seismic sequence, suffered very impressive site effects, including a large seismically-induced debris flow and a high number of small volume landslides. This paper describes the main results of the scientific activities carried out by the authors in this locality in the framework of the unprecedented large-scale Seismic Microzonation project funded by Italian Government in Central Italy for 138 territories. Through an intense field activity, the geological and geomorphologic setting of the study area were revised and updated, including a landslide susceptibility assessment that helped the Italian Department of Civil Protection in the emergency management for temporary housing and, later on, was included in the 3rd Level Seismic Microzonation study implemented by authors while the seismic sequence was still ongoing. A very detailed and reliable subsoil model for this municipality was defined, despite difficulties faced in performing direct and indirect investigations due to the safety restrictions for many areas. The Local Seismic Site response was finally assessed for this locality and the results discussed. A key role in the occurrence of strong site effects into Pescara del Tronto has been played by quaternary deposits having an unexpected heterogeneity under the old village.

Physical stratigraphy and geotechnical properties controlling the local seismic response in explosive volcanic settings: the Stracciacappa maar (central Italy)

Nowadays, policies addressed to prevention and mitigation of seismic risk need a consolidated methodology finalised to the assessment of local seismic response in explosive volcanic settings. The quantitative reconstruction of the subsoil model provides a key instrument to understand how the geometry and the internal architecture of outcropping and buried geological units have influence on the propagation of seismic waves. On this regard, we present a multidisciplinary approach in the test area of the Stracciacappa maar (Sabatini Volcanic District, central Italy), with the aim to reconstruct its physical stratigraphy and to discuss how subsoil heterogeneities control the 1D and 2D local seismic response in such a volcanic setting. We first introduce a new multidisciplinary dataset, including geological (fieldwork and log from a 45-m-thick continuous coring borehole), geophysical (electrical resistivity tomographies, single station noise measurements, and 2D passive seismic arrays), and geotechnical (simple shear tests performed on undisturbed samples) approaches. Then, we reconstruct the subsoil model for the Stracciacappa maar in terms of vertical setting and distribution of its mechanical lithotypes, which we investigate for 1D and 2D finite element site response analyses through the application of two different seismic scenarios: a volcanic event and a tectonic event. The numerical modelling documents a significant ground motion amplification (in the 1–1.5 Hz range) revealed for both seismic scenarios, with a maximum within the centre of the maar. The ground motion amplification is related to both 1D and 2D phenomena including lithological heterogeneity within the upper part of the maar section and interaction of direct S-waves with Rayleigh waves generated at edges of the most superficial lithotypes. Finally, we use these insights to associate the expected distribution of ground motion amplification with the physical stratigraphy of an explosive volcanic setting, with insights for seismic microzonation studies and local seismic response assessment in populated environments.

A FEM analysis of the settlement of a tall building situated on loess subsoil

Abstract In order to correctly model the behaviour of a building under load, it is necessary to take into account the displacement of the subsoil under the foundations. The subsoil is a material with typically non-linear behaviour. This paper presents an example of the modelling of a tall, 14-storey, building located in Lublin. The building was constructed on loess subsoil, with the use of a base slab. The subsoil lying directly beneath the foundations was described using the Modified Cam-Clay model, while the linear elastic perfectly plastic model with the Coulomb-Mohr failure criterion was used for the deeper subsoil. The parameters of the subsoil model were derived on the basis of the results of CPT soundings and laboratory oedometer tests. In numerical FEM analyses, the floors of the building were added in subsequent calculation steps, simulating the actual process of building construction. The results of the calculations involved the displacements taken in the subsequent calculation steps, which were compared with the displacements of 14 geodetic benchmarks placed in the slab.