Geotechnical Properties Research Articles

A CNN-accelerated workflow for stochastic seismic property estimation

As one of the major tools in resolving the non-uniqueness challenge in subsurface interpretation and reservoir characterization, stochastic inversion from post- and pre-stack seismic data remains challenging, which not only requires heavy computational resources but also relies on intensive manual supervision. Inspired by the recent advances in deep learning particularly convolutional neural networks (CNNs) for interdisciplinary data integration, this study proposes a deep learning workflow that enables stochastic property estimation by efficiently integrating seismic images with sparse wells. It starts with sampling a set of property prior models (PPMs) from densely-measured properties at well locations and corrupting local seismic patterns with Gaussian noise. The core idea is to train a structure-guided CNN by mapping the contaminated seismic with the sampled PPMs while enforcing structural consistency to avoid overfitting in the presence of sparse wells. Finally, the baseline and uncertainty of target properties are estimated by running multiple realizations of the trained CNN. As demonstrated by three examples, with minimum efforts of CNN architecture customization according to data availability, the proposed workflow can accommodate various use cases, including rock acoustic/elastic property estimation from 3D post-/angle-stack seismic and soil geotechnical properties from 2D ultra-high-resolution seismic. In all examples, the machine predictions match seismic patterns well and are of high lateral consistency.

Parametric Study of Rainfall-Induced Instability in Fine-Grained Sandy Soil

This study investigates the stability of fine-grained sandy soil slopes under varying rainfall intensities, durations, and geotechnical properties using a parametric analysis within GeoStudio. A total of 4416 unique parameter combinations were analyzed, incorporating variations in unit weight, cohesion, friction angle, slope inclination, slope height, rainfall intensity, and duration. Results reveal that rainfall intensity is the most influential variable on the factor of safety (FS), with higher intensities (e.g., 360 mm/h) on steeper slopes (e.g., 45°) leading to critical FS values below 1, indicating an imminent risk of failure. Under moderate conditions (e.g., 9 mm/h rainfall on slopes of 26.6°), the FS remains above 2. This dataset provides a valuable foundation for training machine learning models to predict slope stability under diverse environmental conditions, contributing to the development of early warning systems for rainfall-induced landslides.

The influence of a Tunnel Boring Machine on a building in Sofia City Center, located above the route of the third Metro line

The construction of the third line of Sofia underground railway (Sofia Metro) used to be one of the major priorities of the geotechnical engineers in the Bulgarian capital for a period of at least two years. Since the first and second lines pass under the existing streets and parks, the third line is designed to go under some buildings erected in the last century. These buildings have been part of the architectural cityscape for years. Such is the case described in the present paper. The underground railway is designed to pass under a building in the Sofia city center. It is a five-story skeletal building, constructed on single and strap foundations. The purpose of the study is to establish whether the settlement due to the passing of the Tunnel Boring Machine (TBM) will adversely affect the structure of the building. The solution is for a single plane task. Data given in the manual of the TBM and the subsoil geotechnical properties are used in order to define the behavior of the soil massif. After the calculations have been made, the relative settlement of the building is determined to be much smaller (1/1662) than the allowable one (1/500). Then the maximum relative settlement is calculated to be 1/1054, which is higher than the average settlement for the whole building, but much less than the allowable. The calculations and comparisons are confirmed in practice.

Preliminary Assessments of Geotechnical Seismic Isolation Design Properties

This paper proposes a method to investigate the design properties of geotechnical seismic isolation (GSI). This technique has been the object of many research contributions, both experimental and numerical. However, methods that may be used by practitioners for design procedures are still unavailable. The formulation presented herein may be used for preliminary assessments of two important properties: the thickness and the shear wave velocity. Three-dimensional advanced numerical simulations were performed with the state-of-the-art platform OpenSees in order to verify the analytical formulation on a benchmark case study. The elongation ratio has been taken as the relevant parameter to discuss the efficiency of GSI in decoupling the soil from the structure. The main findings consist of assessing the dependency of the elongation ratio on two parameters: the thickness and the shear velocity of the GSI layer. In this regard, a novel formulation was proposed in order to make preliminary design assessments that can be used by practitioners for practical applications.

Correction to: Evaluation of Geotechnical Properties of Sediments of the Top Layer of Hypersaline Lakes: The Case of Lake Urmia

Correction to: Evaluation of Geotechnical Properties of Sediments of the Top Layer of Hypersaline Lakes: The Case of Lake Urmia

A re-sampling statistics based imprecise moment independent global sensitivity analysis methodology with limited data of uncorrelated and correlated geotechnical properties

Traditional Global Sensitivity Analysis (GSA) is often performed using variance-based Sobol’s GSA, considering statistics of inputs estimated from limited data to be precise. This can lead to inaccuracies in the importance ranking of inputs due to negligence of – i) epistemic uncertainties in their statistics, and ii) role of other moments of outputs in Sensitivity Indices (SIs). This study overcomes these limitations by proposing an imprecise moment independent GSA methodology. The methodology couples re-sampling statistical techniques, i.e., Jackknifing and Bootstrapping with Monte-Carlo Simulations based Borgonovo’s moment independent GSA to estimate distributions of SIs. The re-sampling techniques estimate epistemic uncertainties in the statistics of inputs by generating re-constituted samples. These epistemic uncertainties are then propagated via Borgonovo’s GSA to estimate their imprecise moment independent SIs. The methodology is further coupled with Nataf’s transformation and Moving Least Square-Response Surface Methods to deal with problems of correlated inputs and lack of explicit input-output relationships. The generalized nature of methodology is demonstrated for three real case studies (one tunnel and two slopes), with different correlation structures between inputs, input-outputs relationships (explicit/implicit), and failure mechanisms. The methodology estimated the distributions of SIs of inputs instead of their point estimates, indicating the propagation of epistemic uncertainties truthfully. The Jackknife-GSA was significantly efficient (∼99 %) with negligible differences in statistics of SIs as compared to Bootstrap-GSA. The correlation between inputs significantly affects the statistics of SIs. Further, a reduction in the imprecision of SIs of inputs with their increasing sample sizes was observed, which is consistent with the general understanding.

Toward Smart Urban Management: Integrating Geographic Information Systems and Geology for Underground Bearing Capacity Prediction in Casablanca City, Morocco

To effectively manage the sustainable urban development of cities, it is crucial to quickly understand the geological and geotechnical attributes of the underground. Carrying out such studies entails significant investments and focused reconnaissance efforts, which might not align seamlessly with large-scale territorial planning initiatives within a city accommodating more than 3 million inhabitants, like Casablanca in Morocco. Additionally, various specific investigations have been conducted by municipal authorities in recent times. The primary aim of this study is to furnish city managers and planners with a tool for informed decision-making, enabling them to explore the geological and geotechnical properties of soil foundations using Geographic Information Systems (GISs) and geostatistics. This database, initially intended for utilization by developers and construction engineers, stands to economize a substantial amount of time and resources. During the urban planning of cities and prior to determining land usage (five- or seven-floor structures), comprehending the mechanical traits (bearing capacity, water levels, etc.) of the soil is crucial. To this end, geological and geotechnical maps, along with a collection of 100 surveys, were gathered and incorporated into a GIS system. These diverse data sources converged to reveal that the underlying composition of the surveyed area comprises silts, calcarenites, marls, graywackes, and siltstones. These formations are attributed to the Middle Cambrian and the Holocene epochs. The resultant geotechnical findings were integrated into the GIS and subjected to interpolation using ordinary kriging. This procedure yielded two distinct maps: one illustrating bearing capacity and the other depicting the substratum. The bearing capacity of the soil in the study zone is rated as moderate, fluctuating between two and four bars. The depth of the foundation remains relatively shallow, ranging from 0.8 m to 4.5 m. The outcomes are highly promising, affirming that the soil in Casablanca boasts commendable geotechnical attributes capable of enduring substantial loads and stresses. Consequently, redirecting future urban planning in the region toward vertical expansion seems judicious, safeguarding Casablanca’s remaining green spaces and the small agricultural belt. The results of this work help to better plan the urban development of the city of Casablanca in a smarter way, thus preserving space, agriculture, and the environment while promoting sustainability. In addition, the databases and maps created through this paper aim for a balanced financial management of city expenditures in urban planning.

Foundation Model Study on Inorganic and Biopolymer Nano Additives Treated Soil—A Step Forward in Nano Additive Soil Stabilization

For almost a decade, various studies have been carried out to prove the suitability of nano additives in enhancing the geotechnical properties of soil. Yet, this line of research is still in its elementary stage, restricting itself to laboratory tests to determine soil’s index and engineering properties blended with varying dosages of nano additives. In other words, research on practical applications of nano additives for soil stabilization is scarce. The present work attempts to investigate the suitability of three different nanomaterials as a load-bearing stratum for shallow foundations. The nano additives were chosen in such a way that each of them is from a different origin. One of them is nano calcium carbonate (inorganic) whereas the other two are nano-sized varieties of natural biopolymers, namely nano chitosan (crustacean-based) and nano carboxymethyl cellulose (plant-based). A series of laboratory tests were initially conducted to determine the strength of all three nano-additive-treated soils at different dosages, which were investigated for 180 days to ensure their long-term performance. This was followed by a foundation model study on untreated soil and on soil treated with optimal dosages of nano additives. The results were validated using finite element software followed by a parametric study to optimize the depth of soil stabilization. It was observed that all three nano additives exhibited a better performance when the top layer had the optimal dosage and the subsequent layers had a relatively lesser dosage.

Terminal glacial overdeepenings: Patterns of erosion, infilling and new constraints on the glaciation history of Northern Switzerland

Glacially overdeepened basins are a common landform of subglacial erosion. However, the controlling erosional–depositional processes and their age remain poorly understood on a global scale. Terminal overdeepenings near the former glacier margins are critical for the understanding of subglacial processes and their development over time. This study examines the geomorphology and sedimentology of buried terminal overdeepenings eroded below the Rhein Glacier and adjacent lobes in the distal northern foreland of the European Alps. The evolution of erosion and infilling in the overdeepened troughs over time is investigated using high-quality drill cores (∼1463 m of core in total) that were logged for lithofacies, petrophysical, geotechnical and compositional properties. The drill data is integrated with 2D-reflection seismics (∼41 km in total) and supplementary subsurface data. This extensive dataset reveals that the studied overdeepened basins include twelve typical facies associations (partially emplaced in characteristic sequences) and characteristic architectural elements. These categories serve as effective tools to reduce the high facies variability and facilitate easier comparison and correlation of the valley fill. Our analysis shows that the formation of terminal overdeepenings on soft sedimentary bedrock (Molasse) is the result of a combination of erosional processes. Subglacial water erosion and evacuation are the dominant processes and active during periods of glacier–bed decoupling and flushing. Direct subglacial erosion occurs during glacier–bed coupling and is documented by bedrock glacitectonites. The valley fill architecture shows that the studied overdeepenings typically undergo a multiphase evolution, with several phases of overdeepening erosion, deposition and partial re-erosion (or re-activation). The combined dataset (including geochronological data) suggests that the overdeepenings were eroded during many, if not all, extensive glaciations during the Middle–Late Pleistocene that reached the distal foreland. These are findings relevant for the large number of overdeepenings known from the Northern Alpine foreland and overdeepened features worldwide. They corroborate the importance of overdeepenings as archives for the paleoenvironmental change and landscape evolution during the Quaternary.

Evaluation of the Effects of Rainwater Infiltration on Slope Instability Mechanisms

Mass movements can be caused by factors from different categories, such as geological factors and climate change. From a geological point of view, the soil profile and the geotechnical properties of the materials are crucial in influencing slope instability. From a climate change perspective, rainfall intensity is one of the main triggers of mass movements. Studies related to rainfall infiltration focus on saturated slope zones; therefore, areas of slope stability with infiltration in the unsaturated zone present large gaps. The Brazilian government environmental diagnostics company, the Mineral Resources Research Company (CPRM), identified the municipality of Areia/PB as a danger zone. The region has landslides that occur mostly during the rainy season. Such events lead to the presumption that rainwater infiltration is responsible for the failure of the municipality’s slopes. Thus, the studies proposed in this research aim to determine the influence of precipitation on the stability of the slopes present in the region. The results show that antecedent precipitation has a greater influence on stability, indicating that daily precipitation alone cannot be used as a determinant for landslides. It was concluded that the role of precipitation in slope stability will vary for different locations, with varying surface conditions, variable tropical rainfall, or different microclimatic conditions.

Suitability techniques for transforming marginal lands to support building infrastructures in parts of Rivers State, Nigeria

This study examined sustainability techniques for transforming marginal lands to support building infrastructures in parts of Rivers State, Nigeria. The study adopted the cross-sectional survey research design method employing the use of standard penetration approach utilizing Geographic Information System analysis. Marginal lands were delineated as margins of watrbodies using the polygon method in ArcGIS, and were created as a feature class for polygon data (shape file). The locations, river margins and roads formed point data, polygon data and line data respectively. Digitisation was achieved using Orthophoto Image in ArcGIS 10.0 software where seven geotechnical boreholes were located and drilled using permission rig to a depth of 10.5m in five local government areas of Rivers State. In-situ standard penetration testing and soil sampling for laboratory geotechnical properties was done using standard laboratory techniques. Findings of the analysis show that silty and sandy clay are the dominant soil within the foundation depth of 1-2.5m which are underlained by clays and sands of varying densities and grain sizes with their specific gravity value of ranges of 1.9 – 2.66 depicting that the areas are underlined by organic, diatomaceous and high porosity permeability soils deposits under water logged conditions. The cohesive strength of the soils vary from 65KN/m 2 - 115KN/m 2, angle of internal friction ranged from 0o – 10o and shear strength ranged from 110KN/m 2 – 147.46KN/m 2 and the allowable bearing capacities of 180.22KN/m 2 – 236.05KN/m 2. The stability techniques for the transformation of the land to support building infrastructures are pre-construction soil stabilization and marginal land reinforcement. The study thus recommends for building summation of consolidated techniques for sustainability of infrastructures.

Case study of bearing capacity failure in a 4-story reinforced concrete building

This case history analyzes the bearing capacity failure of a 4-story reinforced concrete building in Benghazi, Libya, constructed in Fall 2000. The building has a plan area of 65 m² and is supported by an 80 cm thick raft foundation resting on collapsible sandy loess, which can lose shear strength when wet. Several months before the building's failure, nearby construction work caused a broken pipeline, leading to significant water leakage. This moisture infiltrated the soil under the foundation, reducing its bearing capacity, particularly on the northern side. In winter 2002, the building began to tilt northward due to this reduced capacity, although inspections revealed no structural cracks, attributed to the rigidity of the raft foundation and reinforced concrete shear walls. The paper discusses the geotechnical properties of the supporting soil and uses finite element analysis to show that the bearing pressures exceeded allowable limits under wet conditions, emphasizing the importance of moisture content in assessing soil stability. This case highlights the complexities of foundation design and the critical impact of environmental factors on soil behavior, advocating for thorough geotechnical assessments and ongoing monitoring of conditions around structural foundations.

Exploring Soil–Water Characteristic Curves in Transitional Oil Sands Tailings

Soil–water characteristics curves (SWCC) have proved useful in estimating parameters used in modeling unsaturated geotechnical properties of soils including permeability and strength. Either saturation, gravimetric, and instantaneous and initial volumetric water content designation can be used to develop SWCCs. Studies have shown that any of the designations will give good estimates for soils that do not undergo volume change with suction change whereas, for soils that undergo substantial volume change, only saturation and instantaneous volumetric water content designation obtained by incorporating shrinkage curves can give correct estimates. Transition oil sands tailings have fines content that cannot be categorized as sandy or fine materials, and research on volume change with suction change in these materials is limited. In this study, HyProps, Tempe cells, and a chilled-mirror water potential meter were used to measure suction and corresponding water contents for samples that were prepared by mixing coarse sand and Fluid Tailing by ratios that mimic transition zone tailings. Shrinkage tests were also performed to observe the extent of volume change with suction increase. Air Entry Values (AEV) estimated from SWCCs based on gravimetric water content were found to be lower than those estimated from saturation-based SWCCs due to substantial volume changes in these materials with suction increase. The use of saturation water content designation is recommended in estimating AEV for transitional oil sands tailings. This is useful information in predicting the long term unsaturated geotechnical behavior of these materials for environmental management and safety purposes.

Improving Geotechnical Properties of Expansive Subgrade Using Sugar Cane Molasses and Cement

Improving Geotechnical Properties of Expansive Subgrade Using Sugar Cane Molasses and Cement

Assessment of Geotechnical Properties of Al-Fatha Formation in Zurbatiyah Region Eastern Iraq

Assessment of Geotechnical Properties of Al-Fatha Formation in Zurbatiyah Region Eastern Iraq

Micro–Macro-Analysis and Model Derivation of Electrical Resistivity of Ningxia Cement–Loess

In recent years, highway infrastructure in the Ningxia region of China has rapidly advanced. Cement–loess is extensively utilized in the roadbed and foundation reinforcement. It is necessary to conduct micro–macro-analysis and model derivation of the electrical resistivity on Ningxia cement–loess, which are beneficial for both the practical application of electrical resistivity and the evaluation of the geotechnical properties of cement–loess. Therefore, a series of electrical resistivity measurements, microstructural observations (scanning electron microscopy), mineral analyses (thermogravimetric analysis), and theoretical analyses were adopted on the cement–loess. The following conclusions can be drawn: The electrical resistivity is negatively related to dry density and water content, while it is positively related to cement dosage and curing age. A cement dosage of 6% exhibits a lower hydration reaction potential compared to 12%, causing a slower increase in electrical resistivity. The formation of calcium silicate gel around particles results in particle clustering and pore filling, reducing the pore area and increasing electrical resistivity. Increased hydration also decreases microscopic orientation, contributing to a higher electrical resistivity of cement–loess. Finally, a new three-dimensional electrical resistivity model was created, finding that the electrical resistivity of Ningxia cement–loess was determined by the dry density, water content (ρd·w), cement dosage, and curing age (aw·T) in an exponential function form. The new three-dimensional electrical resistivity model could be used in the high-efficiency evaluation of the cement–loess geotechnical parameter, offering valuable insights for the monitoring and maintenance of road infrastructure.

Behavior of Slab-on-Grade Resting on Expansive Soil

Abstract This paper discusses a case study of a residential building in Benghazi that features slab-on-grade foundations supported by expansive soils. Although such structures are uncommon in the area, they can suffer serious damage due to volumetric changes in the soil caused by wetting and drying. The building has a total plan area of 200 m², with tie beams located 1.2 m above the formation level, and expansive soil used as backfill. After being moistened and lightly compacted, 100 mm thick concrete slabs were poured between the tie beams, resulting in varying slab sizes. Following a month of heavy rainfall, significant cracking—longitudinal, diagonal, and warping—occurred in the slabs due to uneven deformation from the expansive soil. The paper includes photographs of these deformations and cracks, along with an analysis of the geotechnical properties of the expansive soil, including its swelling and shrinking characteristics. It also employs an approach to predict the pressure exerted on the slabs due to differential heave.

Evaluation of Geotechnical Properties of Sediments of the Top Layer of Hypersaline Lakes: The Case of Lake Urmia

Evaluation of Geotechnical Properties of Sediments of the Top Layer of Hypersaline Lakes: The Case of Lake Urmia

Geotechnical Characterization of the Magdalena River Subsoil in Magangué, Colombia: A Study Using CPTu and SPT Tests

This study employs Cone Penetration Tests (CPTu) and Standard Penetration Tests (SPT) to analyze the geotechnical properties of the Magdalena River’s riverbed and banks. While these methods are standard in soil characterization, this research innovatively combines CPTu’s continuous profiling with SPT’s localized sampling to develop a nuanced stratigraphic model of the subsurface. This integrated approach provides a comprehensive view of the soil conditions, which is crucial for understanding sediment variability and stability along the riverbanks. The findings from this methodological integration enhance our ability to predict soil behavior under dynamic riverine conditions, offering valuable insights for erosion control and sustainable river management. The study underscores the practical benefits of synergizing traditional testing methods to address geotechnical challenges in river environments.

Geotechnical Properties and Performance of Large-Scale Coastal Dunes Reinforced by Biocementation under Hurricane Wave Conditions

Geotechnical Properties and Performance of Large-Scale Coastal Dunes Reinforced by Biocementation under Hurricane Wave Conditions