A Study on the Influencing Factors on Ground Motion in a Valley Site

A trapezoid valley site is chosen as a research site,and according to numerical models based on orthogonal design,the factors influencing ground motion in the valley site are studied with two-dimensional finite difference method. The influencing factors are ranked,and then the calculation results are verified by ground motion analysis. The conclusions are as follows:there are four factors that have important effects on ground motion of trapezoid valley sites,but the effects are different as the location of sites changes,the influencing factors rank differently with different site locations; The ranking of the influencing factors is the same for all the sites located within a distance of 40m from the valley's side,among them,the most effective one is the valley slope angle ranks,followed by depth-to-width ratio,overburden thickness,at last the input ground motion intensity.The impact of the factors on surface ground motion is roughly the same in the valley sites within a certain distance to the valley side,and the geometric parameters of the valley terrain play a greater part in influencing ground motion. With the increase of distance away from the valley's side,the ranking of the influencing factors also changes,the rating of slope angle moves backward,the ranking of the input ground motion and overburden thickness move ahead. The effect of valley geometric parameters on ground motions is gradually weakened,but the effect of other two influence factors are gradually increased,similar to cases of a horizontal layered site. Strong motion records in Anning River valley site were analyzed,and the results show that the valley topography has a significant amplification effect on ground motion,and that the numerical results of this paper are credible.