Earthquake dynamic response behavior of Xiangchong valley type tailings impoundment in Yunnan, China

Tailings impoundments can potentially collapse due to damage caused by earthquakes,which has frequently occurred around the world.This study takes the proposed valley type tailings impoundment in Yunnan as the research object to analyze the dynamic response behavior under earthquake action with both numerical simulation and physical model test(1:300).The results of both tests show that the dynamic response of the valley type tailings impoundment is characterized by"medium stiffness effect",in other words,in a certain range,the"softer"the unsaturated tailings sand is,the more energy it can dissipate,which leads the decrease of the value of the acceleration amplification factor.In addition,the peak acceleration of the monitoring points increases with the vertical elevation,which indicates that the"elevation amplification effect"exists in the tailings impoundment dynamic response.The middle part of the outer side of the raised embankment reacts more sensitive than the crest,which is similar to the slope dynamic response.The starter dam reacts sensitively under the earthquake excitation,which should be given more attention during the seismic design.The dynamic response rules reflected by the numerical simulation are consistent with the results monitored on the physical model test,although there are some differences between their values.The dynamic response rules of the valley type tailings impoundment can provide basis for the design of the similar projects in this region.

Analytic solution to the magnetotelluric response over anisotropic medium and its discussion

In the present paper,from the second order partial differential equations for solving the magnetotelluric(MT) fields of general anisotropic medium,we first obtained the second order partial differential equations for some anisotropic media with special conductivity(e.g.diagonal anisotropy,transverse anisotropy,azimuthal anisotropy,etc.) by simplifying the electrical conductivity tensor of anisotropic medium.And then we obtained the analytic solutions to MT fields for the case of transverse and azimuthal anisotropy through converting the conductivity parameter based on that of diagonal anisotropy.We further discussed the influence of the selection of integral limit and step length on precision in solving the analytic solutions for MT fields of isotropic medium.Finally,we presented the MT responses of two transverse and azimuthal anisotropic media as well as some applications of the analytic solutions to MT fields of anisotropic medium.