scholarly journals Three-dimensional seismic analysis of high-amplitude anomalies in the shallow subsurface of the Northern Indus Fan: Sedimentary and/or fluid origin

2008 ◽  
Vol 113 (B11) ◽  
Author(s):  
Gérôme Calvès ◽  
Mads Huuse ◽  
Anne Schwab ◽  
Peter Clift
Keyword(s):  
Seismic Analysis ◽  
Three Dimensional ◽  
High Amplitude ◽  
Shallow Subsurface

3-D high‐resolution reflection seismic imaging of unconsolidated glacial and glaciolacustrine sediments: processing and interpretation

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 18-34 ◽  
Author(s):  
Frank Büker ◽  
Alan G. Green ◽  
Heinrich Horstmeyer
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Guided Waves ◽  
Three Dimensional ◽  
High Amplitude ◽  
Seismic Facies ◽  
Small Scale ◽  
Shallow Subsurface ◽  
Reflection Seismic ◽  
Reflecting Boundaries

Shallow 3-D seismic reflection techniques have been used to map glacial deposits in a Swiss mountain valley. A dense distribution of source and receiver positions resulted in a small subsurface sampling of 1.5 m × 1.5 m and a high fold of >40. Common processing operations that included pseudotrue amplitude scaling, deconvolution, and band‐pass filtering successfully enhanced shallow reflections relative to source‐generated noise. Careful top muting helped avoid erroneous stacking of direct and guided waves. Azimuth‐dependent velocity analyses proved to be unnecessary. Three‐dimensional (3-D) migration of the stacked data yielded the final high‐resolution images of the shallow subsurface (15–170 m). Because most reflections and diffractions were migrated to their correct subsurface locations, confident interpretations of 3-D structures were possible. Time slices and cross‐sections along arbitrary directions proved to be powerful analysis tools. Even small‐scale features (<20 m wide), such as subglacial channels and troughs, could be mapped. Five major lithologic units separated by four principal reflecting boundaries were distinguished on the basis of their characteristic seismic facies. The principal reflecting boundaries were semiautomatically tracked through the 3-D data volume. Borehole information allowed the uppermost boundary at 15–27 m to be identified as the top of a 68–80-m-thick sequence of basal and reworked tills characterized by high‐amplitude discontinuous to quasi‐continuous reflections. Low reflectivity of seismic units above and below the till units was associated with finely layered or massive glaciolacustrine clay/silt deposited during and after two principal phases of glaciation (Würm at 28 000 to 10 000 and Riss at 200 000 to 100 000 years before the present). Top of Tertiary Molasse basement was delineated by prominent east‐dipping reflections at variable depths of 85–170 m.

SEISMIC VULNERABILITY ASSESSMENT FOR SAN FRANCISCO TEMPLE IN MORELIA, MEXICO

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 207-2016
Author(s):  
Guillermo Martinez ◽  
David Castillo ◽  
José Jara ◽  
Bertha Olmos
Keyword(s):  
San Francisco ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Middle Part ◽  
Seismic Demands ◽  
Modeling And Analysis ◽  
Seismic Records ◽  
Cracking Pattern ◽  
The Temple

This paper presents a first approximation of the seismic vulnerability of a sixteenth century building which is part of the historical center of Morelia, Mexico. The city was declared World Heritage by United Nations Educational, Scientific and Cultural Organization in 1991. The modeling and analysis of the building was carried out using a three-dimensional elastic tetrahedral finite elements model which was subjected to probabilistic seismic demands with recurrences of 500 yrs and 1000 yrs in addition to real seismic records. The model was able to correctly identify cracking pattern in different parts of the temple due to gravitational forces. High seismic vulnerability of the arched window and the walls of the middle part of the bell tower of the temple was indicated by the seismic analysis of the model.

The structure of weakly compressible grid-generated turbulence

2001 ◽  
Vol 432 ◽  
pp. 219-283 ◽  
Author(s):  
G. BRIASSULIS ◽  
J. H. AGUI ◽  
Y. ANDREOPOULOS
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Three Dimensional ◽  
High Amplitude ◽  
Time Dependent ◽  
Wide Range ◽  
Dynamical Flow ◽  
Set Up ◽  
Decay Exponent

A decaying compressible nearly homogeneous and nearly isotropic grid-generated turbulent flow has been set up in a large scale shock tube research facility. Experiments have been performed using instrumentation with spatial resolution of the order of 7 to 26 Kolmogorov viscous length scales. A variety of turbulence-generating grids provided a wide range of turbulence scales with bulk flow Mach numbers ranging from 0.3 to 0.6 and turbulent Reynolds numbers up to 700. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was also found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A possible mechanism responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid. Measurements of the time-dependent, three dimensional vorticity vectors were attempted for the first time with a 12-wire miniature probe. This also allowed estimates of dilatation, compressible dissipation and dilatational stretching to be obtained. It was found that the fluctuations of these quantities increase with increasing mean Mach number of the flow. The time-dependent signals of enstrophy, vortex stretching/tilting vector and dilatational stretching vector were found to exhibit a rather strong intermittent behaviour which is characterized by high-amplitude bursts with values up to 8 times their r.m.s. within periods of less violent and longer lived events. Several of these bursts are evident in all the signals, suggesting the existence of a dynamical flow phenomenon as a common cause.

scholarly journals Seismic Vertical Component Effects on the Pathology of a Historical Structure, Xana, Located in Greece

2021 ◽  
Vol 7 ◽  
Author(s):  
Vasiliki Terzi ◽  
Asimina Athanatopoulou
Keyword(s):  
Seismic Analysis ◽  
Near Field ◽  
Three Dimensional ◽  
Vertical Component ◽  
Element Model ◽  
Material Behavior ◽  
Initial State ◽  
Tensile Cracks ◽  
First Case ◽  
Three Dimensional Finite Element

The present study aims to investigate the effects of the seismic vertical component on the pathology of Xana monument which is a typical caravanserai, constructed circa 1375–1385 and is located in the archeological site of the municipality of Trainapoulis, Greece. The monument’s plan is rectangular and the three-leaf masonry circumferential walls support a hemicylindrical dome constructed by bricks and mortar. The structure consisted of two consecutive parts: one for the travelers and one for the animals. Nowadays, the triangular roof, that covered the structure, and the first part of the monument do not exist. Xana suffers tensile cracks along the interior surface of the dome, a vertical fracture located on the northern wall and vertical tensile cracks located at the openings. A three-dimensional finite element model of the initial state of Xana is constructed. Non-linear material behavior is taken into account as well as soil-structure interaction effects. An adequate number of near-field earthquake events has been used, taking into account that they are related to significant vertical components. The structural seismic analysis is conducted for two cases. The first case refers to the action of the two horizontal-component of ground motions while the second one takes into account the three translational seismic components. The pathology estimation reveals important information concerning the structural effects due to vertical accelerations.

scholarly journals Three-dimensional seismic analysis of concrete gravity dams considering foundation flexibility

2021 ◽  
Vol 25 (1) ◽  
pp. 88-98
Author(s):  
Mokhtar Messaad ◽  
Messoud Bourezane ◽  
Mohamed Latrache ◽  
Amina Tahar Berrabah ◽  
Djamel Ouzendja
Keyword(s):  
Young’S Modulus ◽  
Seismic Analysis ◽  
Young's Modulus ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Total System ◽  
Dam Reservoir ◽  
Principal Stresses ◽  
Foundation Soil ◽  
North West

Abstract Concrete dams are considered as complex construction systems that play a major role in the context of both economic and strategic utilities. Taking into account reservoir and foundation presence in modeling the dam-reservoir-foundation interaction phenomenon leads to a more realistic evaluation of the total system behavior. The article discusses the dynamic behavior of dam-reservoir-foundation system under seismic loading using Ansys finite element code. Oued Fodda concrete dam, situated at Chlef, in North-West of Algeria, was chosen as a case study. Parametric study was also performed for different ratios between foundation Young's modulus and dam Young's modulus E f /E d (which varies from 0.5 to 4). Added mass approach was used to model the fluid reservoir. The obtained results indicate that when dam Young's modulus and foundation Young's modulus are equal, the foundation soil leads to less displacements in the dam body and decreases the principal stresses as well as shear stresses.

scholarly journals Characteristic of Shallow Subsurface Quaternary Sediment in Nongsa Isle, Part of Putri Islands, Batam, Based on Georadar Data Interpretation

2019 ◽  
Vol 34 (2) ◽  
Author(s):  
Undang Hernawan ◽  
Nineu Yayu Geurhaneu ◽  
Muhammad Zulfikar
Keyword(s):  
Sedimentary Facies ◽  
Data Interpretation ◽  
High Amplitude ◽  
Spatial Filter ◽  
Geological Condition ◽  
Depositional Facies ◽  
Shallow Subsurface ◽  
Equipment Type ◽  
Ground Penetrating ◽  
Radar Facies

Nongsa Isle belongs to Putri Islands in Batam, is the outermost island that need to be protected either from natural hazards and anthropogenic factor. Therefore, this study was conducted by performing Ground Penetrating Radar analysis, in order to understand the geological condition particularly sedimentology and its process. We used Sirveyor 20 GPR equipment type with MLF antenna frequency 40 Mhz and Radan 5 as processing software, which include time zero correction, spatial filter, deconvolution, migration and adjustment of amplitude and signal gain. Data interpretation was conducted based on radar facies methodology that describes georadar image/radargram. The study result showed differences of sedimentary facies based on three differences of radar facies units, with the first layer (unit 1) is the youngest unit has thicknesses ranging from 3.5 – 5 m that characterized by parallel, strong reflector, high amplitude and continuous reflector configurations, unit 2 from 5 – 11 meter of depth, indicates parallel reflector pattern with medium-high amplitude and continuous, and unit 3 which is the oldest unit with thickness until penetration limit (11 – 20 m), characterized by a configuration of sub parallel – hummocky reflectors that are undulating, low-medium amplitude reflectors. Based on radar facies characteristics such as reflector configuration, reflection amplitude, and reflection continuity, the differencies of depositional facies are changes from fluvial – coastal plain.

scholarly journals The Effect Analysis of Strain Rate on Power Transmission Tower-Line System under Seismic Excitation

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Li Tian ◽  
Wenming Wang ◽  
Hui Qian
Keyword(s):  
Strain Rate ◽  
Power Transmission ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Seismic Excitation ◽  
Transmission Tower ◽  
Base Shear ◽  
Effect Analysis ◽  
Line System

The effect analysis of strain rate on power transmission tower-line system under seismic excitation is studied in this paper. A three-dimensional finite element model of a transmission tower-line system is created based on a real project. Using theoretical analysis and numerical simulation, incremental dynamic analysis of the power transmission tower-line system is conducted to investigate the effect of strain rate on the nonlinear responses of the transmission tower and line. The results show that the effect of strain rate on the transmission tower generally decreases the maximum top displacements, but it would increase the maximum base shear forces, and thus it is necessary to consider the effect of strain rate on the seismic analysis of the transmission tower. The effect of strain rate could be ignored for the seismic analysis of the conductors and ground lines, but the responses of the ground lines considering strain rate effect are larger than those of the conductors. The results could provide a reference for the seismic design of the transmission tower-line system.

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