scholarly journals The Usefulness of Seismic Surveys for Geotechnical Engineering in Karst: Some Practical Examples

Geosciences ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 406
Author(s):  
Mario Bačić ◽  
Lovorka Librić ◽  
Danijela Jurić Kaćunić ◽  
Meho Saša Kovačević
Keyword(s):  
Large Strain ◽  
Geotechnical Engineering ◽  
Geophysical Methods ◽  
Near Surface ◽  
Distinctive Features ◽  
Seismic Surveys ◽  
Karstic Features ◽  
Engineering Investigation ◽  
Control Campaign

Having in mind uncertainties linked with the nature of rock masses, it is a challenge for geotechnical engineers to characterize them in a credible manner, especially if the rock mass in question is a notoriously complex karst with its distinctive features such as voids and discontinuities. A large range of geophysical methods are useful tools in the characterization efforts and their utilization in karst environments nowadays is a non-negotiable requirement, even though near-surface scattering significantly affects the acquired data. This paper demonstrates the versatile applications of seismic geophysical methods for geotechnical engineering in karst, from mapping of near-surface karstic features to the application of elastic wave velocities in determination of small to large strain stiffness of karst. The highlighted practical examples offer a step forward from the traditional interpretation of seismic surveys, making them a prosperous tool in geotechnical engineering investigation works, design and quality control campaign.

Détermination de la géométrie et des propriétés physiques du pergélisol discontinu de la région de Schefferville

1977 ◽  
Vol 14 (3) ◽  
pp. 431-443 ◽  
Author(s):  
Maurice K.-Seguin
Keyword(s):  
Electrical Resistivity ◽  
Regional Scale ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Near Surface ◽  
Vertical Extension ◽  
Discontinuous Permafrost ◽  
Propriétés Physiques ◽  
Lower Limits

The various parameters used to predict on a regional scale the lateral and vertical extension of permafrost are the following: surface temperature, thermal conductivity of rocks, and geothermal flow configuration. Locally this type of data is generally not sufficient and far too inaccurate. The use of geophysical methods at the surface and in boreholes in addition to existing thermal data helps to improve the degree of accuracy in the prediction of spatial distribution of permafrost in a given area. These geophysical methods include seismic refraction, electrical resistivity, and spontaneous and induced polarizations.Because of the properties of permafrost, seismic refraction at surface is useful only to determine the top of the permafrost whereas electrical resistivity (electric logging near surface) allows the determination of the upper and lower limits of permafrost. Seismic refraction, resistivity, and spontaneous and induced polarizations in boreholes were deemed more promising to determine masses or lenses of permafrost.Moreover, it was possible to correlate temperature and electrical resistivity measurements in boreholes, thus allowing the drawing of isothermal curves from electric logging in areas of continuous and discontinuous permafrost, at least when it is 'marginal'.The data for this study were obtained from the experimental station at Schefferville, Québec. [Journal Translation]

scholarly journals Semi-Automatic Fractional Snow Cover Monitoring from Near-Surface Remote Sensing in Grassland

2021 ◽  
Vol 13 (11) ◽  
pp. 2045
Author(s):  
Anaí Caparó Bellido ◽  
Bradley C. Rundquist
Keyword(s):  
Snow Cover ◽  
Near Infrared ◽  
Accuracy Assessment ◽  
Important Variable ◽  
Field Station ◽  
Near Surface ◽  
Fractional Snow Cover ◽  
Rgb Images ◽  
Phenological Metrics

Snow cover is an important variable in both climatological and hydrological studies because of its relationship to environmental energy and mass flux. However, variability in snow cover can confound satellite-based efforts to monitor vegetation phenology. This research explores the utility of the PhenoCam Network cameras to estimate Fractional Snow Cover (FSC) in grassland. The goal is to operationalize FSC estimates from PhenoCams to inform and improve the satellite-based determination of phenological metrics. The study site is the Oakville Prairie Biological Field Station, located near Grand Forks, North Dakota. We developed a semi-automated process to estimate FSC from PhenoCam images through Python coding. Compared with previous research employing RGB images only, our use of the monochrome RGB + NIR (near-infrared) reduced pixel misclassification and increased accuracy. The results had an average RMSE of less than 8% FSC compared to visual estimates. Our pixel-based accuracy assessment showed that the overall accuracy of the images selected for validation was 92%. This is a promising outcome, although not every PhenoCam Network system has NIR capability.

scholarly journals Mapping the Distribution of Buried Glacier Ice – An Example From Lago Delle Locce, Monte Rosa, Italian Alps

1986 ◽  
Vol 8 ◽  
pp. 78-81 ◽  
Author(s):  
W. Haeberli ◽  
F. Epifani
Keyword(s):  
Snow Cover ◽  
Seismic Refraction ◽  
Italian Alps ◽  
Frozen Ground ◽  
Near Surface ◽  
Winter Snow ◽  
Glacier Ice ◽  
Geoelectrical Resistivity ◽  
Monte Rosa

Techniques for mapping the distribution of buried glacier ice are discussed and the results, from a study carried out within the framework of flood protection work in the Italian Alps, are presented. Bottom temperatures of the winter snow cover (BTS) primarily indicate the heat flow conditions in the underlying ground and mainly depend on the presence or absence of an ice layer beneath the surface. Determination of BTS values is therefore an inexpensive method for quickly mapping the near-surface underground ice in areas where there is 1 m or more of winter snow cover. At greater depths, and/or when more detail is required, geoelectrical resistivity soundings and seismic refraction soundings are most commonly used to investigate underground ice. A combination of the two sounding techniques allows the vertical extent and the main characteristics (frozen ground, dead glacier ice) to be determined in at least a semi-quantitative way. Complications mainly arise from irregularity in the horizontal extension of the studied underground ice bodies, and they may have to be overcome by expensive core drillings and borehole measurements. Widespread occurrence of buried glacier ice was observed in morainic deposits, surrounding an ice-dammed lake near Macugnaga, Italy.

scholarly journals Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling

Solid Earth ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 1685-1705
Author(s):  
Silvia Salas-Romero ◽  
Alireza Malehmir ◽  
Ian Snowball ◽  
Benoît Dessirier
Keyword(s):  
Large Scale ◽  
Geophysical Methods ◽  
Hydrological Modelling ◽  
P Wave ◽  
Coarse Grained ◽  
Near Surface ◽  
Reflection Seismic ◽  
Geotechnical Investigations ◽  
Quick Clay ◽  
Near Surface Geophysics

Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.

scholarly journals DETERMINATION OF PRODUCTION WELL'S COLLECTORS POROSITY IN SOUTH-GEOLOGICAL AREA

2016 ◽  
pp. 25-29
Author(s):  
G. E. Stroyanetskaya
Keyword(s):  
Electrical Resistivity ◽  
Geophysical Methods ◽  
Caliper Measurement ◽  
Porosity Coefficient

The problems of collectors at the stage of calculating the reserves in operating incline directional wells, penetrated on clay, polymer-clay solution, polymer washing liquid with hydrochloric-calcium foundation were considered. The electrical resistivity of the solution and the washing liquid from 0.1 to 1 O·mm. According to geophysical methods, establishing of the criteria for the allocation of the collectors requires coring. The main methods for the isolation of collectors are lateral, microlaterolog survey and caliper measurement. The techniques of the gas-saturated collectors porosity coefficient determination were considered.

scholarly journals Mechanisms of public administration in post-soviet societies

2021 ◽  
Vol 5 (S2) ◽  
pp. 354-365
Author(s):  
Sergii A. Vavreniuk ◽  
Oleksandr M. Nepomnyashchyy ◽  
Oleksandra A. Marusheva ◽  
Iryna A. Lahunova ◽  
Svitlana M. Shostak
Keyword(s):  
Soviet Union ◽  
Public Administration ◽  
Former Soviet Union ◽  
Distinctive Features ◽  
Current State ◽  
Independent States ◽  
Modernization Process ◽  
Former Ussr ◽  
Newly Independent States

This article focuses on the problem of public administration in the countries of the former Soviet Union. It reveals the economic development issues of the states of the post-Soviet space, considers the main common and distinctive features for the newly independent states. The central problem raised in the article is the determination of the current state of the modernization process in post-Soviet societies. The author assumes the presence of demodernization and presents an argument in confirming his opinion. In addition, the article reveals the issues of the modern political state of such countries of the former USSR as Russia, Ukraine and Uzbekistan. The author traces the process of demodernization and dependence of political and social development on the governing elitist groups, leading to authoritarianism as opposed to the supposed democracy and modernization.

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