Influence of a weak interlayer of different thicknesses and dip angles on seismic acceleration responses of a slope

The weak layer in a geologic body is characterized by its material property,thickness,depth,dip angle,extending direction,etc. A weak layer of different characteristics always causes the significant different seismic responses in a geologic body,through the interaction between the weak interlayer and seismic waves. To study the rock slopes with a weak interlayer,four slope models were designed for conducting the shaking table tests. The characteristic parameters of the weak interlayer include the thickness (3 and 5 cm) and dip angle (0° and 20°). Based on the test data,a previous paper made a rather detailed comparative analysis on whether or not a weak interlayer influences the horizontal acceleration responses and the deformation and failure features of model slopes. The present paper aims at uncovering the influence of the thickness and dip angle on the horizontal acceleration responses of model slopes. By means of comparative analysis,two phenomena are observed. One is that the thick interlayer produces wave-isolation effect in the model slope relative to the thin interlayer,and the other one is that the horizontal interlayer produces the stronger response than the anti-dip interlayer. However,it should be noted that the two phenomena doesn’t occur in all elevations along the slope surface,but are observed mainly in the upper part of slope,especially in relative elevation h/H = 0. 5 and at the crest. For instance,at the crest,the PHA in model with thin interlayer is 1. 8-2. 6 times larger than that in model with thick interlayer as the two interlayers are horizontally extended,and the PHA in model with horizontal interlayer is 1. 8 times larger than that in model with anti-dip interlayer as the two interlayers are thin in thickness. Another important result is the thickness plays the control role in PHA response in relative elevations with 0． 75≤ h/H≤1． 0 and at the slope toe,while the dip angle plays the control role in relative elevations with 0． 25<h/H≤ 0． 5. Herein,the control effect indicates the maximum response difference caused by different thicknesses or dip angles.