Numerical modeling of elastic waves using the random-enhanced QPSO algorithm

2021 ◽  
Author(s):  
Meng-quan Zhu ◽  
Zhi-yang Wang ◽  
Hong Liu ◽  
You-ming Li ◽  
Du-li Yu
Keyword(s):  
Numerical Modeling ◽  
Elastic Waves

scholarly journals Numerical modeling of elastic waves across imperfect contacts.

2006 ◽  
Vol 28 (1) ◽  
pp. 172-205 ◽  
Author(s):  
Bruno Lombard ◽  
Joël Piraux
Keyword(s):  
Numerical Modeling ◽  
Elastic Waves

A transparent boundary technique for numerical modeling of elastic waves

Geophysics ◽  
1999 ◽  
Vol 64 (3) ◽  
pp. 963-966 ◽  
Author(s):  
Jianlin Zhu
Keyword(s):  
Numerical Modeling ◽  
Boundary Conditions ◽  
Elastic Waves ◽  
Wave Equations ◽  
Normal Incidence ◽  
Absorbing Boundary Conditions ◽  
S Wave ◽  
Absorbing Boundary ◽  
S Waves ◽  
Elastic Wave Equations

In numerical modeling of wave motions, strong reflections from artificial model boundaries may contaminate or mask true reflections from the interior model interfaces. Hence, developing a kind of exterior model boundary transparent to the outgoing waves is of critical importance. Among proposed solutions, e.g., Smith (1974), Kausel and Tassoulas (1981), and Higdon (1991), the most widely used may be the Clayton and Engquist (1977) method of absorbing boundary conditions, based on paraxial approximations for acoustic and elastic‐wave equations. However, absorbing boundary conditions make the reflection coefficients zero only for normal incidence, and suppression of reflected S-waves (Clayton and Engquist, 1977) becomes poorer as the ratio of P- to S-wave velocity ([Formula: see text]) becomes larger.

EVALUATION OF THE TIME-DEPENDENT CHARACTERISTICS OF GROUTED SAND USING AN ELASTIC WAVE

2008 ◽  
Vol 22 (11) ◽  
pp. 899-904 ◽  
Author(s):  
JOOWON KIM ◽  
KI-IL SONG ◽  
GYE-CHUN CHO ◽  
SEOK-WON LEE
Keyword(s):  
Numerical Modeling ◽  
Elastic Wave ◽  
Elastic Waves ◽  
Experimental Tests ◽  
Time Dependent ◽  
Soft Ground ◽  
Large Section ◽  
Wave Velocities ◽  
Dependent Behavior ◽  
Strength And Stiffness

For a better evaluation of a grouted zone during and after tunnel construction involving weak soil layers, it is necessary to estimate the characteristics of grouted zone effectively. This study suggests a method that can be used for characterizing the time-dependent behavior of pre-reinforced zones around a large section of tunnel in soft ground using elastic waves. Experimental tests were performed to characterize the time-dependent behavior of the pre-reinforced zone. Experimental results show that shear strengths as well as elastic wave velocities increase with the curing time. Thus, shear strength or strength parameters can be uniquely correlated to elastic wave velocities. It is possible to characterize grouted soils around tunnel using elastic waves. Time-dependent strength and stiffness parameters in the experimental tests were applied in a numerical modeling of a large-section tunnel in soft ground, taking into account its construction sequence. According to the results of the numerical modeling, displacement results for fewer than 2~3 days of constant time boundary conditions are nearly identical to the analysis results of the time-dependent condition. The proposed analysis method, which combines experimental and numerical procedures while considering the time-dependent effect of the pre-reinforced zone on the tunnel behavior, will provide a reliable and practical design basis and a means of analysis for large-section tunnels in soft ground.

Remarks on nonlinear elastic waves with null conditions

2020 ◽  
Vol 26 ◽  
pp. 121
Author(s):  
Dongbing Zha ◽  
Weimin Peng
Keyword(s):  
Initial Data ◽  
Global Existence ◽  
Elastic Waves ◽  
Wave Equations ◽  
Alternative Proof ◽  
Classical Solutions ◽  
Small Initial Data ◽  
Hyperelastic Materials ◽  
Variational Structure ◽  
Nonlinear Elastic

For the Cauchy problem of nonlinear elastic wave equations for 3D isotropic, homogeneous and hyperelastic materials with null conditions, global existence of classical solutions with small initial data was proved in R. Agemi (Invent. Math. 142 (2000) 225–250) and T. C. Sideris (Ann. Math. 151 (2000) 849–874) independently. In this paper, we will give some remarks and an alternative proof for it. First, we give the explicit variational structure of nonlinear elastic waves. Thus we can identify whether materials satisfy the null condition by checking the stored energy function directly. Furthermore, by some careful analyses on the nonlinear structure, we show that the Helmholtz projection, which is usually considered to be ill-suited for nonlinear analysis, can be in fact used to show the global existence result. We also improve the amount of Sobolev regularity of initial data, which seems optimal in the framework of classical solutions.

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