Seismic Response Analysis of Horizontal Layer Slope with Soft and Hard Rock Combination

Abstract

Slope of subhorizontal layer structure is among typical natural structures and the different soft and hard rock combinations in upper and lower slope parts differ in seismic response. Taking into consideration some slope failure phenomena of two-sided slopes with banded structure ridges in “5.12” Wenchuan Earthquake, simulation experiment are made to research two types of horizontal structure slopes with hard-upper and soft-lower and soft-upper and hard-lower parts, by means of numerical simulation analysis and simulating experiment on vibration table. Research results show that for slope with hard-upper and soft-lower parts, its upper hard rock body is inclined to undergo global shearing deformation, along contact layer with underlying soft rock body, and the upper slope body is apt to go through collapse and pull-crack. For slope with soft -upper and hard -lower parts, influenced relatively more strongly by its lower hard rock part, rock body possibly shows cracking deformation similar to sliding and compression cracking, which may extend upward or downward along the contact layer. Moreover, the shoulder of two-sided slope is apt to undergo pull-crack and that, to some degree, relieves integral stress and sliding deformation of the upper soft rocky body. Therefore the whole rock body goes through little sliding deformation. Research result confirms the actual shatter slope failure, which further verifies the view that horizontal seismic action force plays main role in slope failure.