Cylindrical Valley Research Articles

Amplification of obliquely incident waves by a cylindrical valley embedded in a layered half-space : F. C. P. De Barros & J. E. Luco, Soil Dynamics & Earthquake Engineering, 14(3), 1995, pp 163–175

Amplification of obliquely incident waves by a cylindrical valley embedded in a layered half-space : F. C. P. De Barros & J. E. Luco, Soil Dynamics & Earthquake Engineering, 14(3), 1995, pp 163–175

Three-dimensional response of a layered cylindrical valley embedded in a layered half-space : J. E. Luco & F. C. P. De Barros, Earthquake Engineering & Structural Dynamics, 24(1), 1995, pp 109–125

Three-dimensional response of a layered cylindrical valley embedded in a layered half-space : J. E. Luco & F. C. P. De Barros, Earthquake Engineering & Structural Dynamics, 24(1), 1995, pp 109–125

Three‐dimensional response of a layered cylindrical valley embedded in a layered half‐space

AbstractAn indirect boundary integral method to obtain the three‐dimensional response of an infinitely long, layered, viscoelastic valley of arbitrary cross‐section embedded in a layered viscoelastic half‐space is presented. The valley is excited by homogeneous plane waves impinging at an oblique angle with respect to the axis of the valley. The method and associated computer programs are tested by comparison with available results in the limiting two‐dimensional case of incidence normal to the axis of the valley. Additional comparisons with previous three‐dimensional results obtained by a hybrid finite element‐boundary integral method for cylindrical valleys subjected to obliquely incident waves show large differences. However, the results obtained here for an infinitely long valley appear to be in some agreement with earlier results for an elongated prolate semi‐ellipsoidal valley and with results obtained by a discrete wavenumber boundary element approach. An extensive bibliography on the dynamic response of valleys is also presented.

Amplification of obliquely incident waves by a cylindrical valley embedded in a layered half-space

Extensive numerical results illustrating the harmonic three-dimensional response of cylindrical valleys embedded in uniform and layered media and subjected to obliquely incident P-, SV- and SH-waves are presented. In particular, the effects of the horizontal and vertical angles of incidence, some of the effects of layering and the dependence of the results on the frequency of the excitation are examined in some detail.

Scattering of obliquely incident seismic waves by a cylindrical valley in a layered half space

Scattering of obliquely incident seismic waves by a cylindrical valley in a layered half space

Scattering of obliquely incident seismic waves by a cylindrical valley in a layered half‐space

AbstractThree‐dimensional scattering of seismic waves by a cylindrical alluvial valley embedded in a layered half‐space is investigated by using the combination of the boundary integral representation and the finite element method. The surface displacements due to incident plane harmonic body waves (P, SV and SH) propagating at an arbitrary angle to the axis of the cylindrical valley are evaluated numerically for two semi‐elliptical alluvial valleys. The presence of the layer is found to have a strong effect on the amplification of the surface displacements in some cases. The three‐dimensional motion seems to be quite critical and may cause large amplification. The surface ground motion becomes significant when compared with corresponding free‐field motion as the wavelengths become comparable to the characteristic length of the valley. The maximum amplification always occurs atop the valley. Numerical results show that the amplitude and the amplification pattern of the surface displacement strongly depend upon the frequency, the angle and the type of the incident waves.

Ground motion amplification by cylindrical valleys embedded in a layered medium : Bouden, M; Khair, K R; Datta, S K Earthq Engng Struct DynamV19, N4, May 1990, P497–512

Ground motion amplification by cylindrical valleys embedded in a layered medium : Bouden, M; Khair, K R; Datta, S K Earthq Engng Struct DynamV19, N4, May 1990, P497–512

Ground motion amplification by cylindrical valleys embedded in a layered medium

AbstractThe phenomenon of localized amplification of seismic waves due to subsurface irregularities has attracted the attention of seismologists and engineers for many years. In this paper we present a hybrid numerical method to investigate the ground motion amplification due to sedimentary basins. This method combines the integral representation and the finite element to solve the scattering problem due to an arbitrary cylindrical scatterer. A study is done on two shapes of valleys to show the effect of the angle of incidence, the incident wave type and the layering on the amplification of the surface displacement components by different valleys.

Normal modes of a "cylindrical valley" of alluvium


 
 
 
 Some normal modes of vibration are deduced for a cylindrical volume of high bulk modulus, low shear modulus material, embedded in an infinite half space of rigid material. The manner in which they may be excited by travelling waves in the rigid material is examined. The relevance of such processes is discussed with regard to the enhancement of structural damage on soft soil during an earthquake.
 
 
 

Models illustrating John Farey's figures of stratified masses

A partial collection of laminated wooden models illustrative of John Farey's (1766–1826) ideas on the effects of faulting on stratified masses, expressed as two plates of 56 block diagrams in his ‘General View of the Agriculture and Minerals of Derbyshire’ published in 1811, are preserved in the collection of the Geological Society of London. The models have been identified and described. An economical method of construction involved sawing two conjoined laminated blocks along a ‘plane of denudation’, thus giving two distinct models illustrative of different diagrams. Also illustrated are the patterns of strata formed by cutting cylindrical valleys across the models. Farey foresaw the possibility of illustrating the effect of conical and branching excavations on outcrop patterns in various combinations of tilted and faulted strata. The diagrams were intended as a visual aid to the mineral surveyor in deciphering fault displacements in the simple stratified successions of strata in the mining area of Derbyshire.

The Inverse Problem for Valley Glacier Flow

AbstractWe seek to infer the velocities within a cylindrical valley glacier from measured surface velocities. In the Newtonian viscous case, an explicit finite-difference scheme does not fulfil von Neumann’s condition for numerical stability. How this fact does not contradict the existence of Somigliana’s analytical solution is explained. A procedure is given which delays the onset of instability and allows velocities at shallow depths to be determined.

The Inverse Problem for Valley Glacier Flow

Abstract We seek to infer the velocities within a cylindrical valley glacier from measured surface velocities. In the Newtonian viscous case, an explicit finite-difference scheme does not fulfil von Neumann’s condition for numerical stability. How this fact does not contradict the existence of Somigliana’s analytical solution is explained. A procedure is given which delays the onset of instability and allows velocities at shallow depths to be determined.