Effect of initial static shear on cyclic behavior of sand

Abstract

Liquefaction of saturated sand deposits poses a considerable threat to the safety of various engineering structures during earthquakes. Among various factors that have been identified in the laboratory to affect the liquefaction behavior of sand, the initial static driving shear is a key one in the liquefaction analysis involving earth dams, slopes and high-rise buildings. While the cyclic behavior of sand without initial static shear has been studied extensively, a general consensus has still not yet come up regarding the initial shear effect due primarily to a lack of convergence and consistency in the limited available data, resulting in significant difficulty and uncertainty in quantifying the effect. This paper presents an experimental study of the initial shear effect on cyclic liquefaction behavior of sand, focusing mainly on very loose sand. The data base produced is able to improve the current understanding and to clarify the existing uncertainty. A new concept, termed as threshold α, is proposed along with the use of zero reversal line to better characterize the effect of initial static shear stress.