No abstract

SUMMARYThis paper presents the preliminary results of an extensive numerical parametric study on seismic behaviour of two-dimensional semi-sine-shaped valleys subjected to vertically propagating incident in-plane compression and shear waves. The medium is assumed to have a linear elastic constitutive behaviour. All calculations are executed in time-domain using the direct boundary element method. Clear perspectives of the amplification patterns of the valley are presented by investigation of the frequencydomain responses. It is shown that wavelength, site geometry and in a less order of importance, wave type and material parameters, are the independent key parameters governing the valley's amplification pattern. Some simple rules are obtained which could be used in seismic microzonation and seismic design of structures founded inside the valley.

Seepage in the foundation and abutments of a dam can lead to wasting of the stored water in the reservoir, erosion of the foundation materials and increasing the uplift pressure. It can endanger the long term stability of the dam. Cement grouting is one of the seepage control methods which is generally implemented according to the Lugeon test results. In this study, the grout volume has been examined against Q-value, Lugeon number, SPI (Secondary permeability index) value and joint apertures in the Bakhtiari dam site. In Bakhtiari dam site, the left and the right abutment trial grouting boreholes were drilled up to the final depth of 60 and 100 m, respectively. Limestone of the Sarvak Formation is the dominant rock type in the site. The Q-system parameters have been evaluated by eyeexamination of rock cores, the Lugeon numbers and SPI values have been deduced from the water pressure tests and the joint apertures have been calculated based on the permeability of rock mass and the joints spacing. The Q-value, the Lugeon number, the SPI value and the joint aperture have been compared with measured cement take and grout take in the trial grouting boreholes. A general correlation exists, especially when the mentioned parameters have been compared with normalized grout take. Against these general agreements the coefficients of determination for the fitted relations are low or moderate, and it seems that more research has been needed to assessing a reliable predictive relation for the grout and cement takes.

This paper presents the most important results of an extensive numerical parametric study on seismic behavior of two-dimensional semi-sine shaped hills subjected to vertically propagating incident SV and P waves. The medium is assumed to have a linear elastic constitutive behavior. All calculations are executed in time-domain using the direct boundary element method. Clear perspectives of the amplification patterns of the hill are presented by investigation of the frequency-domain responses. It is shown that wave length, site geometry and in a less order of importance, wave type and material parameters, are the independent key parameters governing the hill's amplification pattern. Some preliminary simple equations and tables are presented which could be used as useful starting estimates to account for topography in seismic microzonation studies as well as seismic design of structures located on the hill.

SUMMARYThis paper presents a formulation of a time-domain three-dimensional boundary element method for site response analysis of topographic structures. The boundary element algorithm that uses the presented time-convoluted traction kernels is applied to site response analyses of topographic structures. The seismic responses of canyon and ridge subjected to incident P and S waves are analyzed to demonstrate the accuracy of the kernels and the applicability of the presented boundary element algorithm for site response analysis of topographic structures. Seismic response analyses of three-dimensional Gaussian-shaped ridges show that the three-dimensional axisymmetric ridge has a more amplification potential compared with three-dimensional non-axisymmetric elongated and two-dimensional ridges, if the ridge is impinged by incident waves with wavelength of about the ridge's width.