Horizontal Acoustic Barriers for Protection from Seismic Waves

Sergey V Kuznetsov,Aybek E Nafasov

doi:10.1155/2011/150310

Sergey V Kuznetsov, Aybek E Nafasov

Open Access

https://doi.org/10.1155/2011/150310

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Abstract

The basic idea of a seismic barrier is to protect an area occupied by a building or a group of buildings from seismic waves. Depending on nature of seismic waves that are most probable in a specific region, different kinds of seismic barriers can be suggested. Herein, we consider a kind of a seismic barrier that represents a relatively thin surface layer that prevents surface seismic waves from propagating. The ideas for these barriers are based on one Chadwick′s result concerning nonpropagation condition for Rayleigh waves in a clamped half‐space, and Love′s theorem that describes condition of nonexistence for Love waves. The numerical simulations reveal that to be effective the length of the horizontal barriers should be comparable to the typical wavelength.

Highlights

Current methods for preventing failure of structures due to seismic activity can be divided into two groups: (i) approaches for creating seismically stable structures and joints; this group contains different methods ensuring either active or passive protection; (ii) approaches for creating a kind of seismic barrier preventing seismic waves from transmitting wave energy into a protected region
The considered seismic barriers can be of two types: vertical, aimed to reflect, trap, and dissipate most of the seismic wave energy; horizontal, based on Chadwick and Smith [5] and Love [6] theorems and aimed to prevent certain types of seismic waves from propagation, see (Figure 1)
Horizontal barriers can be constructed by modifying properties of the outer layer preventing the corresponding surface wave from propagation

Summary

Introduction

The considered seismic barriers can be of two types: vertical, aimed to reflect, trap, and dissipate most of the seismic wave energy; horizontal, based on Chadwick and Smith [5] and Love [6] theorems and aimed to prevent certain types of seismic waves from propagation, see (Figure 1) Another interesting approach is to create a “rough” surface of the half-space to force the propagating Rayleigh wave scatter by caves and swellings, see (Figure 2), where part of a free surface with the sinusoidal roughness is pictured. Horizontal barriers can be constructed by modifying properties of the outer layer preventing the corresponding surface wave from propagation. Methods for constructing the corrector within the twoscale asymptotic expansion methods are discussed by Michel et al [17], Cecchi and Rizzi [18]

The Main Types of Surface Acoustic Waves

Horizontal Seismic Barriers

Concluding Remarks