Seismic Response of Alluvial Valleys Subject to Oblique Incidence of Shear Waves

2021 ◽  
pp. 1-25
Author(s):  
Dana Amini ◽  
Behrouz Gatmiri ◽  
Pooneh Maghoul
Keyword(s):  
Seismic Response ◽  
Oblique Incidence ◽  
Shear Waves

scholarly journals Effects of Oblique Incidence of SV Waves on Nonlinear Seismic Response of a Lined Arched Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Dunyu Lyu ◽  
Sha Ma ◽  
Chu Yu ◽  
Congcong Liu ◽  
Xiaowei Wang ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Wave Field ◽  
Seismic Response ◽  
Seismic Wave ◽  
Oblique Incidence ◽  
Incident Angle ◽  
Three Dimensional ◽  
Seismic Wave Propagation ◽  
Finite Element Program ◽  
Artificial Boundaries

The incident direction of earthquake motion is an important factor affecting the seismic response of underground structures. In this study, a three-dimensional (3D) oblique incidence method of SV waves is proposed and the effects of incident angles of SV waves on the seismic response of a lined arched tunnel are evaluated. Based on wave field decomposition principle and equivalent node force method and together with viscous-spring artificial boundary, the oblique incidence method of SV waves is implemented by transforming seismic wave field into the equivalent nodal forces acting on the artificial boundaries. By deriving the distance of the incident waves and the reflected wave on free surface to artificial boundaries, this method can comprehensively consider the phase difference of the seismic wave propagation and the influence of the damping effect of the rock medium on the seismic wave propagation. The method is programed into a dynamic finite element program and its effectiveness is examined by a numerical example. Consequently, the oblique incidence method is applied to evaluate the seismic behaviors of the tunnel. The numerical results reveal that (1) the oblique incidence of the seismic wave results in a larger seismic response; (2) the response amplitudes of the stress and displacement increase with the increase of incident angles and reaching the maximum in the case of 30° incident angle; (3) the damage extent increases with an increase in the incident angles, and the oblique incidence of the seismic wave is believed to increase the spatial difference of damage distribution.

scholarly journals Oblique Incidence Ultrasonic Reflectometry Device Based on c-axis Tilted ScAlN Films for Evaluating Viscoelastic Properties of Liquids Above 100 MHz

2021 ◽  
Author(s):  
Sarina Kinoshita ◽  
Takahiko Yanagitani
Keyword(s):  
Viscoelastic Properties ◽  
Oblique Incidence ◽  
Shear Waves ◽  
High Sensitivity ◽  
Shear Mode ◽  
Complex Reflection ◽  
Real Time Measurement ◽  
Sensitivity Evaluation ◽  
Fluid Properties ◽  
Shear Elasticity

Abstract Ultrasound-based evaluation of fluid properties allows for real-time measurement of small amounts of liquid samples. The ultrasonic reflection method is used to obtain the complex reflection coefficient, which can be used to evaluate the viscoelastic properties of liquids. However, this method has not been used with shear waves at frequencies above 100 MHz because shear-mode piezoelectric films are difficult to obtain at such frequencies. We propose using the oblique incidence reflectometry with quasi-shear waves excited by c-axis tilted scandium aluminum nitride (ScAlN) thin films to realize high-sensitivity evaluation of the viscoelastic properties of liquids in the above 100 MHz. In experiments, the shear elasticity and shear viscosity of glycerin solutions were estimated from their complex reflection coefficients.

Seismic response for an isosceles triangle hill subjected to anti-plane shear waves

2021 ◽  
Author(s):  
Yunqiu Song ◽  
Xinzhu Li ◽  
Zailin Yang ◽  
Yong Yang ◽  
Menghan Sun
Keyword(s):  
Seismic Response ◽  
Shear Waves ◽  
Isosceles Triangle ◽  
Plane Shear

Seismic Response of Gravity Dam under Oblique Incidence of Seismic Waves

2013 ◽  
Vol 838-841 ◽  
pp. 1585-1590
Author(s):  
Li Chen ◽  
Liao Jun Zhang
Keyword(s):  
Seismic Response ◽  
Oblique Incidence ◽  
Seismic Waves ◽  
Near Field ◽  
P Wave ◽  
Gravity Dam ◽  
Response Analysis ◽  
Uniform Motion ◽  
Obvious Effect ◽  
Obliquely Incident

The selection of proper seismic input is essential for seismic response analysis of the gravity dam structures. For the near-field earthquakes, the direction of seismic waves is not always considered as vertical. The non-uniform motion produced by oblique incidence can cause significant influence to the structure. In this study, the obliquely incident method is applied in the finite element model of a typical section of a gravity dam located in southwestern China. The seismic response under obliquely incident of plane P wave and plane SV with different incident angles and tilt directions are discussed. The results show that the oblique incidence has an obvious effect on the seismic response of the gravity dam, and the inconsistence produced by oblique incidence cannot be neglected.

scholarly journals Seismic Response of Irregular Triangular Alluvial Valleys under Shear Waves Using Spectral Elements

2018 ◽  
Vol 4 (11) ◽  
pp. 2652 ◽  
Author(s):  
Saeed Hosseinpour ◽  
Jafar Najafizadeh
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Time Domain ◽  
Seismic Behavior ◽  
Shear Waves ◽  
Spectral Element ◽  
Spectral Elements ◽  
The Finite Element Method ◽  
Maximum Value ◽  
The Time Domain

The present study investigates seismic response problems of triangular uniform irregular alluvial valleys under shear waves using a finite element spectral method. Alluvial valleys; affect the shape and properties of alluvial materials on the response and seismic behavior of the valley surface due to the geometry conditions. Therefore this study aims to illustrate the plots and magnitude of amplification values for irregular alluvial valleys in a two-dimensional triangular manner, with the characteristics of homogeneous alluvial materials and different geometric characteristics. The analysis in the time domain was performed based on the finite element method of the spectral element (SFEM) using NASEM software, developed by Najafizadeh. The valleys are analyzed with the slope angles of 15, 30, 45 and 60 degrees on one side and in opposite directions with a slope of 45 degrees and with a maximum depth of 50 meters for the alluvial valley. The horizontal amplification curves in the alluvial valley's points from the analysis reach a maximum value at a given frequency, which can be an ideology for determining the frequency of irregular triangular alluvial valleys under different slope valley angles. The results of natural valley frequencies indicate that with decreasing slope of the valley, the natural frequency of the valley decreases, as well as amplification plots are related to the slope of the valley.

Sign in / Sign up

Export Citation Format

Share Document