Knowledge Based Prediction of Standard Penetration Resistance of Soil Using Geotechnical Database

The current study aimed at predicting standard penetration resistance (N) of soil using particle sizes and Atterberg's limits. The geotechnical database was created subsequent to the field and laboratory testing. The sample collection points were distributed in a mesh grid pattern to have uniform sampling consistency. Artificial Neural Networks (ANN) were trained on the database to build a knowledge-based understanding of the interrelation of the given soil parameters. To check the efficacy of the model, the validation was carried out by predicting standard penetration resistance (N) for another 30 samples which were not included in the training data (444 samples). The trained ANN model has been found to predict N values in close agreement with the N values measured in the field. The novelty of the research work is the standard penetration prediction employing basic physical properties of soil. This proves the efficacy of the proposed model for the target civil engineering application. Doi: 10.28991/CEJ-SP2021-07-01 Full Text: PDF

Tridimensional geotechnical database modeling as a subsidy to the standardization of geospatial geotechnical data

Geotechnical data is often produced and managed by several producers in isolation, in their own formats and standards, which aim to meet the unique needs of specific users, because there is not a defined geospatial geotechnical data storage standard. This article presents the physical implementation of a three-dimensional geotechnical database, based on a data model generated using the Object Modeling Technique for Geographic Applications, composed of information produced by the academy and various administrative institutions of the Federal District Government. More than four thousand quantitative e qualitative geotechnical investigations are available in this structured database that can be accessed by anyone with some geographic information system knowledge using QGIS. Considering that the compiled information was stored by their producers in distinct formats and most of them in a non-digital and without locational information, this work reinforces the need to adoption a standardization of geospatial geotechnical data storage on a unified basis compatible with the National Spatial Data Bank to disseminate this information.

Mapping faults in an urban environment from borehole data (Oviedo, NW Spain)

<p>The detailed geological mapping in built-up areas presents challenges that arise mainly from the covering of outcrops, and the erase of natural geomorphological features during earthmoving works related to urban development. However, it also benefits from the existence of closely spaced site investigation data, including boreholes, not commonly available outside the cities.</p><p>This contribution explains the procedure carried out to improve the interpretation of faults below the city centre of an urban core located in NW Spain. Oviedo is placed on a basin formed by an alternation of sub-horizontal carbonate and siliciclastic formations of Cretaceous age, over which lies an unconformable cover of Paleogene fluvial-lacustrine deposits mostly composed by clays and marls. The paleorelief over which the Paleogene was deposited results in great lateral changes in the thickness of these sediments. Moreover, the basin was deformed during the Alpine convergence in northern Iberia developing an open syncline oriented East-West. During the shortening, a number of minor faults cutting across the gently dipping Cretaceous and Paleogene deposits affect moderately the cartographic pattern of lithostratigraphic units.</p><p>Therefore, this research was focused on the preferential use of information on the ground provided by hundreds of rotary boreholes managed through a GIS-type geotechnical database. The procedure of semiautomatic identification consisted essentially of investigating the spatial variations of the boundary between two Cretaceous formations, in order to find anomalies attributable to fault displacements. In using this boundary as a strain marker for post-depositional deformation, two scales were approached, one aimed at the identification of large faults, and another with greater detail based on trend-surface analysis for fractures of smaller size and local incidence (vertical offset less than 10 m).</p><p>The research has allowed to discuss faults deduced in previous geological maps, helping to interpret thickenings related to the paleorelief, and also to recognize the existence of structures not described in the regional literature. This study provides also better constrains to the analysis of the structural relationships between the faults affecting the Mesozoic-Palaeogene basin, and the Alpine reactivation of the underlying Palaeozoic basement.</p>

Parameters calibration in rainfall induced landslides in the Langhe area (1994)

<p>In this work we have tackled as a ‘cold case’ the prolonged rainfall and flood event occurred in the Piedmont region (Northern Italy) in November 1994, when several hundreds of shallow landslides occurred. The aim is to investigate the key trigger factors of the landslides and to put some focus on the possibility to obtain calibrated parameters thanks to the use of a regional geotechnical database.</p><p>This research has been motivated by the effort to close the methodological and conceptual gap between the use of low-detail approaches, proposed to explore wide investigation domains and that of complex ones, applied to single hillslope scale, typically relying on finite elements solutions.</p><p>To achieve the above-mentioned goals, a simple model was preferred (i.e. that of Rosso, Rulli, Vannucchi, 2006), since it allowed a better check on the sensitivity of soil parameter values to the instability condition, under the assumption that these were the main sources of uncertainty.</p><p>With reference to the 1994 event, a database of 238 observed landslide has been used, for which well-documented geometries and geotechnical parameters are available.</p><p>To address the specific aim of cohesion and permeability validation, the safety factor expression from Limit Equilibrium Analysis has been targeted to assume the value 1 for all the considered slopes subjected to the actual (measured) rainfall.</p><p>The comparison between locally calibrated cohesion and permeability and the reference ones found in the database shows some differences; in particular, in several cases, safety factors quite lower than 1 have been derived, compared to those obtained using the published parameter values. The overall uncertainty resulting from this gap has been analysed for a limited (5%) number of carefully examined landslides and it will lay the foundations for subsequent, more geometrically accurate, investigations.</p>

Geophysical research and geotechnical database construction for selecting design parameters of mining systems

A passport to success in mineral mining is the detailed geomechanical information on enclosing rock mass and structure of a mineral deposit. These data are used as a framework for the rock mass stability estimation. These data are taken into account in critical decision-making on mine design, which finally determines the mine safety and performance. The authors review the current methods of acquisition of geotechnical data at the stage of geological exploration. The structural model is constructed for Shiraldzhin gold deposit in Kyrgyzstan. The structural modeling used the data of geophysical measurements in 6 boreholes. It is shown that construction of a geotechnical database helps design future parameters of a mining system. Geophysical borehole investigations have an advantage over the conventional coring techniques in terms of cost and accuracy. The geophysical borehole measurements using a borehole image scanner requires maintenance of borehole parameters: diameter not less than HQ; angle not less 55°; mouth casing down to bedding rocks. Finally, the major requirement is scanning to be accomplished immediately after drilling (within one day depending on rock stability).

Development of a Unified Geotechnical Database and Data Processing on the Example of Nur-Sultan City

Development of a geotechnical database for the young capital of Kazakhstan, Nur-Sultan city, became a paramount concern of both the scientific community and industry. The creation of the Kazakhstan model of the geotechnical database was based on a fixed dataset which included a city map with determined X, Y, and H coordinates and the user generated data obtained from the materials of engineering and geological surveys from more than 2000 boreholes. Based on the assessment of the built-up area of the city, six main engineering-geological elements (EGE) were identified. The territory of the city was regrouped into eight zones instead of the previous six based on the geological origin and stratigraphy interposition of the EGE. Engineering properties of the soils were considered for physical and mechanical characteristics, where the plasticity limits demonstrated an accurate correlation to the elasticity modulus E and distribution boundaries between the alluvial and eluvial types of the soil on the graph. So, the increased liquid and plastic limits are replicated by higher values of elasticity modulus E, and hence better strength characteristics of a particular soil layer and vice versa, while the moisture content and soil density did not show any obvious pattern and requires additional verification on the construction site. Finally, a geotechnical map was built for the driven piles and the optimal variations in the pile length for each zone were determined.

Recommendations for the minimum number of laboratory tests for intact rock

The design of mining excavations in rock requires access to a representative geotechnical model that includes the mechanical properties of the rock mass. The available geotechnical data provide the necessary input to analytical, numerical, and empirical design tools. Consequently, any geotechnical analysis is influenced by the quality of the input data. Therefore, to understand and mitigate the design risk caused by data uncertainty, it is critical to evaluate the level of confidence in the collected geotechnical data. A practical limitation of current mine design practice is the absence of quantitative guidelines to select the number of laboratory tests required. This investigation employs small-sampling theory to determine the minimum number of tests necessary to obtain predefined confidence intervals in intact rock estimates at South African mines. A key element of this work is the introduction of geotechnical domain complexity as a significant factor in establishing quantitative recommendations for the required minimum number of laboratory tests. A tangible contribution of this work is the development of an original methodology for planning laboratory testing campaigns for a new mining project or for updating the geotechnical database of operating mines. The proposed quantitative methods can eventually replace subjective assessments in addressing data collection requirements.

A Geotechnical Database for Utah (GeoDU) enabling quantification of geotechnical properties of surficial geologic units for geohazard assessments

Geotechnical borehole information is often used for liquefaction hazard mapping, but can be highly variable in terms of quantity and quality. In addition, geotechnical borehole logs are often provided as images in reports rather than delivered in a structured, queryable database, which makes the logs and supplementary information difficult to organize particularly across a large geographic area. In contrast, surficial geologic mapping is generally available and often accessible in geographic information systems (GIS) format. This article’s objective is to describe the compilation of a geotechnical database for regional mapping purposes and to demonstrate the value of documenting geotechnical data into a consistent data format. Specifically, this article describes the development of three geotechnical borehole databases compiled in Utah, which has been coined the Geotechnical Database for Utah (GeoDU). The database is used to quantify geotechnical properties for subsequent liquefaction evaluations of surficial geologic units comprising similar depositional environment and age. The resulting GeoDU is an important resource for future efforts with many applications including community data sharing and planning for preliminary geotechnical site investigations.