Wyniki wyszukiwania - Biblioteka Nauki

1

Analysis of simultaneous time series of indoor, outdoor and soil air radon concentrations, meteorological and seismic data

100%

Janik M. , Bossew P.

Nukleonika

|

2016

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tom Vol. 61, No. 3

295--302

EN

It is well known that the temporal dynamic of indoor and outdoor radon concentrations show complex patterns, which are partly not easy to interpret. Clearly, for physical reasons, they must be related to possibly variable conditions of radon generation, migration and atmospheric dispersion and accumulation. The aim of this study was to analyse long-time series of simultaneously measured indoor and outdoor radon concentrations, together with environmental quantities, which may act as control variables of Rn. The study was performed in Chiba, Japan, using two ionization chambers for parallel indoor and outdoor radon concentrations measurements over 4 years. Meteorological and seismic data were obtained from the Japan Metrological Agency (JMA).

2

Structural and seismic sequence stratigraphy analysis of seismic and biostratigraphy data from an onshore field, Niger Delta, Nigeria

88%

Emujakporue G. O. , Eyo A. J.

World News of Natural Sciences

|

2019

|

tom 22

190-199

EN

The structural and sequence stratigraphy of a Niger Delta onshore field has been analysed from seismic and biostratigraphy data in order to assess the hydrocarbon potential of the area. Seven faults F1, F2, F3, F4, F5, F6 and F7 were delineated in the seismic sections. The faults, F1, F4, F6 and F7 are synthetic faults, while F2, F3 and F5 are antithetic. Two horizons H1 and H2 were identified in the seismic sections within the time window of 2200-2600 ms. The seismic sequence stratigraphy analysis revealed five sequence boundaries S1, S2, S3, S4 and S5, which represent four depositional sequences. Four maximum flooding surfaces (MFS) were also delineated in the seismic data. The analysis of the biostratigraphy data thus revealed four sequence boundaries (S1, S2, S3, S4) and three maximum surfaces (MFS1, MFS2 and MF3). The age of the sequence boundary ranges from 13.1Ma to 8.3 Ma. The age of the observed maximum flooding surfaces ranges from 12.8 Ma to 9.4 Ma. In vertical succession, the depositional sequences were identified by the order; sequence boundary, lowstand system tract (LST), Transgressive system tract (TST), Maximum flooding surface (MFS), and Highstand system tract (HST). The lowstand system tract is made up of stacking pattern of sand, while the transgressive system tract thinned into the condense section.

3

On obtaining effective elasticity tensors with entries zeroing method

75%

Gierlach B. , Danek T.

Geology, Geophysics and Environment

|

2018

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tom Vol. 44, no. 2

259--274

EN

The purpose of this paper is to propose a new method for obtaining tensors expressing certain symmetries, called effective elasticity tensors, and their optimal orientation. The generally anisotropic tensor being the result of in situ seismic measurements describes the elastic properties of a medium. It can be approximated with a tensor of a specific symmetry class. With a known symmetry class and orientation, one can better describe geological structure elements like layers and fissures. A method used to obtain effective tensor in the previous papers (i.e. Danek & Slawinski 2015) is based on minimizing the Frobenius norm between the measured and effective tensor of a chosen symmetry class in the same coordinate system. In this paper, we propose a new approach for obtaining the effective tensor with the assumption of a certain symmetry class. The entry zeroing method assumes the minimization of the target function, being the measure of similarity with the form of the effective tensor for the specific class. The optimization of orientation is made by means of the Particle Swarm Optimization (PSO) algorithm and transformations were parameterised with quaternions. To analyse the obtained results, the Monte-Carlo method was used. After thousands of runs of PSO optimization, values of quaternion parts and tensor entries were obtained. Then, thousands of realizations of generally anisotropic tensors described with normal distributions of entries were generated. Each of these tensors was the subject of separate PSO optimization, and the distributions of rotated tensor entries were obtained. The results obtained were compared with solutions of the method based on the Frobenius distances (Danek et al. 2013).

4

Parameter estimation of non-stationary random media driven by partially stacked seismic data

75%

Lin Y. , Zhang G. , Chen S. , Huang M. , Wang B.

Acta Geophysica

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2022

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tom Vol. 70, no 5

2119--2133

EN

The estimation of non-stationary random medium parameters is the key to the application of random medium theory in fine seismic exploration. We propose a method for estimating non-stationary random medium parameters from partially stacked seismic data. To begin with, the relationship between seismic data and random medium p-wave velocity, s-wave velocity, density model in random medium is described, and the principle and method of estimating the parameters of autocorrelation function of random medium are introduced in this paper. Subsequently, the specific steps of applying the power spectrum method for non-stationary random media parameter estimation are also presented. The feasibility and correctness of the method are verified through the estimation test of the two-dimensional theoretical model. Eventually, the estimation test of non-stationary random medium parameters is carried out by field seismic data. The results show that the non-stationary random medium parameters can better describe the elastic parameter information of the subsurface media and provide a reference for the initial model construction of the elastic parameters, reflecting that the method has good application prospects. Compared with previous studies, this method extends the random medium parameter estimation from stationary to non-stationary and from single wave impedance random medium parameter to multi-elastic parameter random medium parameters. It provides a basis for the in-depth application of random media theory in field data. Meanwhile, this estimation method based on the power spectrum method has the advantage of being intuitive and easy to interpret. However, there are also problems in smoothing effect, which needs further improvement and refinement.

5

Seismotectonic investigations

75%

Komatina-Petrovic S. , Stanic S.

Reports on Geodesy

|

2006

|

tom z. 5/80

445--450

6

Geodynamic considerations on the space-time migration

75%

Besutiu L. , Cadicheanu N. , Zlăgnean L.

Reports on Geodesy

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2006

|

tom z. 5/80

393--398

7

The influence of the soil constitutive models on the seismic analysis of pile-supported wharf structures with batter piles in cut-slope rock dike

75%

Deghoul L. , Gabi S. , Hamrouni A.

Studia Geotechnica et Mechanica

|

2020

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tom Vol. 42, nr 3

191--209

EN

In coastal regions, earthquakes caused severe damage to marine structures. Many researchers have conducted numerical investigations in order to understand the dynamic behavior of these structures. The most frequently used model in numerical calculations of soil is the linear-elastic perfectly plastic model with a Mohr-Coulomb failure criterion (MC model). It is recommended to use this model to represent a first-order approximation of soil behavior. Therefore, it is necessary to accommodate soil constitutive models for the specific geotechnical problems. In this paper, three soil constitutive models with different accuracy were applied by using the two-dimensional finite element software PLAXIS to study the behavior of pile-supported wharf embedded in rock dike, under the 1989 Loma Prieta earthquake. These models are: a linear-elastic perfectly plastic model (MC model), an elastoplastic model with isotropic hardening (HS model), and the Hardening Soil model with an extension to the small-strain stiffness (HSS model). A typical pile-supported wharf structure with batter piles from the western United States ports was selected to perform the study. The wharf included cut-slope (sliver) rock dike configuration, which is constituted by a thin layer of rockfill overlaid by a slope of loose sand. The foundation soil and the backfill soil behind the wharf were all dense sand. The soil parameters used in the study were calibrated in numerical soil element tests (Oedometer and Triaxial tests). The wharf displacement and pore pressure results obtained using models with different accuracy were compared to the numerical results of Heidary-Torkamani et al.[28] It was found that the Hardening Soil model with small-strain stiffness (HSS model) gives clearly better results than the MC and HS models. Afterwards, the pile displacements in sloping rockfill were analyzed. The displacement time histories of the rock dike at the top and at the toe were also exposed. It can be noted that during the earthquake there was a significant lateral ground displacement at the upper part of the embankment due to the liquefaction of loose sand. This movement caused displacement at the dike top greater than its displacement at the toe. Consequently, the behavior of the wharf was affected and the pile displacements were important, specially the piles closest to the dike top.

8

Geodynamics of the South Balkans - seismotectonic model, fractality and nonlinear properties

75%

Ranguelov B. , Dimitrova S. , Gospodinov D. , Lamykina G.

Reports on Geodesy

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2006

|

tom z. 5/80

609--625

9

Considerations on the Black Sea opening and its seismotectonic consequences

75%

Besutiu L. , Zugravescu D.

Reports on Geodesy

|

2006

|

tom z. 5/80

429--433

10

Seismic Structure-Soil-Structure Interaction (SSSI) between piled neighboring bridges: Influence of height ratio

75%

Alfach M. T.

Studia Geotechnica et Mechanica

|

2024

|

tom Vol. 46, nr 1

45--75

EN

This paper explores the impact of height ratios on the seismic Structure-Soil-Structure Interaction (SSSI) for three adjacent bridges with varying superstructure masses (Mst = 350, 1050, 350 t) through 3D numerical simulations. A comprehensive series of numerical analyses has been conducted across different height ratios (R = 1, 1.1, 1.15, 1.2, 1.25, 1.5, 2, and 3) to assess their influence on superstructure acceleration and the internal forces within the foundation piles. The bridges under investigation are supported by groups of piles embedded in nonlinear clay. The numerical simulations were executed using fast Lagrangian analysis of continua in three dimensions (FLAC 3D), a three-dimensional finite differences modeling software. The findings revealed that variations in mass ratios significantly impact the SSSI effects on superstructure acceleration and pile internal forces. Notably, adverse effects were more pronounced for mass ratios of R = 1.1 and 1.2, leading to an increase in bending moment, shear force, and superstructure acceleration by up to 237.8%, 291.4%, and 70.33%, respectively. In contrast, a mass ratio of R = 3 resulted in a decrease in bending moment, shear force, and superstructure acceleration by up to 72%, 82.14%, and 81.13%, respectively. This implies that a careful arrangement of adjacent structures with different masses can be employed effectively to manage the (SSSI) effects.

11

Geophysical Study for the Recognition of the Water Resources of the Turonian Aquifer in the Eastern Part of the Boudnib Basin (Errachidia, Morocco)

75%

Laaraj F. , Benabdelhadi M. , Chibout M. , Lahrach A. , Benslimane A.

Ecological Engineering & Environmental Technology

|

2023

|

tom Vol. 24, iss. 3

79--89

EN

The region of Boudnib is located in southeast Morocco and depends on the territorial region of Drâa-Tafilalet and the province of Errachidia. It has a water deficit due to the lack of rainfall in the region and the overexploitation of groundwater. 76 electrical drillings were drilled and correlated with borehole and seismic reflection data to understand and identify the structure and geometry of the deep aquifer to facilitate the selection of future boreholes and wells. After the interpretation of all data of vertical electrical sounding, we exploited it to make an interpretation of the results. Indeed, we have established an isohypse of the resistant roof maps also geoelectric sections representing the different electrical discontinuities present in the study area, their nature as well as the zones favorable to the exploitation of the Turonian aquifer waters.

12

An innovative time-saving method of turning for vessels conducting seismic surveys

75%

Walus A. , Gucma L. , Putynkowski G.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

|

2016

|

tom nr 45 (117)

207--211

EN

The paper presents a turning method saving time and energy while conducting seismic surveys and an example of its application. The introduced turning method is based on use of the ocean currents / tidal streams as a supporting factor. The turning technique is applicable for vessels towing streamers and conducting line-change or other maneuvers similar to 180° turn. Chosen forces affecting seismic in-water equipment as well as behavior of the spread are briefly shown and explained. Some advantages over traditional turning techniques are here described. The method was applied onboard the seismic vessel Geo Pacific reducing significantly time required for line-change.

13

Seismicity of Bulgaria

63%

Christoskov L. , Solakov D. , Simeonova S.

Reports on Geodesy

|

2006

|

tom z. 5/80

127--135

14

Simplified reliability analysis of multi hazard risk in gravity dams via machine learning techniques

63%

Hariri-Ardebili M. A. , Pourkamali-Anaraki F.

Archives of Civil and Mechanical Engineering

|

2018

|

tom Vol. 18, no. 2

592--610

EN

Deterministic analysis does not provide a comprehensive model for concrete dam response under multi-hazard risk. Thus, the use of probabilistic approach is usually recommended which is problematic due to high computational demand. This paper presents a simplified reliability analysis framework for gravity dams subjected to flooding, earthquakes, and aging. A group of time-variant degradation models are proposed for different random variables. Response of the dam is presented by explicit limit state functions. The probability of failure is directly computed by either classical Monte Carlo simulation or the refined importance sampling technique. Next, three machine learning techniques (i.e., K-nearest neighbor, support vector machine, and naive Bayes classifier) are adopted for binary classification of the structural results. These methods are then demonstrated in terms of accuracy, applicability and computational time for prediction of the failure probability. Results are then generalized for different dam classes (based on the height-to-width ratio), various water levels, earthquake intensity, degradation rate, and cross-correlation between the random variables. Finally, a sigmoid-type function is proposed for analytical calculation of the failure probability for different classes of gravity dams. This function is then specialized for the hydrological hazard and the failure surface is presented as a direct function of the dam's height and width.

15

Fine detection on water abundance of sandstone by joint inversion of seismic and CSAMT: a case study in the western Ordos Basin, China

63%

Dong Y. , Cheng J. , Wen L. , Cheng P. , Li F. , Jiao J. , Huang Q.

Acta Geophysica

|

2022

|

tom Vol. 70, no 5

2045--2056

EN

The Ningdong mining area in the western Ordos Basin, China, mainly mines coal seam in Yan'an group, where its overlying rock is a thick sandstone layer of the Middle Jurassic Zhiluo Formation. This rock layer poses a direct water hazard threat to the coal mining if it is water-rich. The water abundant rock layer in the upper strata of Zhiluo Formation forms a low-resistivity overburden layer, decreasing the resolution of controlled source audio magnetotelluric (CSAMT) method in detecting water-bearing in the lower part of Zhiluo Formation sandstone layer of coal seam direct roof. Therefore, under the influence of the low resistivity overburden of the upper sandstone, how to accurately detect the aquosity of the lower sandstone layer is of great importance to the safe mining of coal mines in the region. On the basis of CSAMT detection, combined with high-resolution seismic exploration method, the joint inversion of seismic and CSAMT is realized by using cross-gradient operation between the seismic wave impedance attributes clustered by particle swarm algorithm and CSAMT inversion model. The seismic data fitting term in the joint inversion objective function is discarded, and the pseudo-2D inversion method is used for CSAMT to reduce the calculation cost of the inversion. A 3D geological model conforming to the hydrogeological characteristics of the Ningdong mining area is established, and the joint inversion test between seismic and CSAMT is conducted, proving the feasibility and applicability of joint inversion to detect the water enrichment of sandstone in this area. The accuracy of the seismic and CSAMT joint inversion results is verified by combining the engineering example of water abundance detection in the sandstone layer in Maiduoshan coal mine that accorded with the typical hydrogeological characteristics of Ningdong mining area and the results of later downhole drilling exposures, which is remarkably better than the single method. The research shows that the joint inversion of seismic and CSAMT can accurately identify the water abundance of the lower sandstone layer and its range under the influence of the upper low resistance sandstone overburden and achieve the purpose of fine detection of the water abundances of the lower sandstone layer of the Zhiluo Formation. The joint inversion can provide important safety geological guarantee for the mining of coal seams in the Ningdong mining area in the western part of Ordos Basin.

16

Ceny ukształtowały trend

63%

Trześniowski Z.

Wiadomości Naftowe i Gazownicze

|

2006

|

tom R. 9, Nr 6 (98)

4-5

17

Geodynamic investigations in Serbia and Montenegro

63%

Komatina M. , Komatina-Petrovic S.

Reports on Geodesy

|

2006

|

tom z. 5/80

437--440

18

On the geodynamics of Bulgarian lands through seismological data

63%

Botev E. , Slejko D. , Bressan G. , Bragato P. , Glavcheva R.

Reports on Geodesy

|

2006

|

tom z. 5/80

149--168

19

Seismic anisotropy of a fractured rock during CO2 injection: a feasibility study

63%

Ganguli S. S. , Kumar P. , Dimri V. P.

Acta Geophysica

|

2019

|

tom Vol. 67, no. 1

141--148

EN

Fluid substitution plays the key role in reservoir characterization, leading to enhance understanding of the influence of fluids on seismic parameters. In general, fluid substitution tool assumes that the Earth is as an isotropic medium, which may not represent the practical field situation. Nevertheless, anisotropic fluid substitution provides important insights into the processes that control the anisotropic seismic response of a fractured rock when subjected to CO2 injection for enhanced oil recovery and its geological sequestration. Here, we examine the influence of fluid substitution in a porous yet fractured reservoir for quantitative interpretation of seismic data. This investigation involves anisotropic Gassmann’s equation and linear slip theory for fluid substitution in a transversely isotropic media with a horizontal axis of symmetry (HTI). We present a synthetic case by conceptualizing a double-layered half-space model with upper layer as shale and bottom layer as HTI sandstone, representing an Indian mature reservoir. The effects of variation in background porosity and fracture weaknesses on anisotropic (Thomsen’s) parameters, acoustic parameters including amplitude variation with angle have also been discussed. We observe that brine and oil sands to be associated with the highest elastic moduli, while CO2 sands exhibit contrasting trend. It is noteworthy that CO2 is more sensitive to fracture weakness when compared to the other reservoir fluids such as hydrocarbons and brines, as P-wave moduli (as much as 37.1%) and velocity (as high as 12.2%) reduces significantly with the increase in fracture weakness. Further, Gassmann’s assumption is validated as we noticed unchanged values in shear-wave moduli and shear-wave splitting parameter (γ) for various fluid types.

20

Seismologic investigations

63%

Stanic I. , Komatina-Petrovic S.

Reports on Geodesy

|

2006

|

tom z. 5/80

441--444