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|Title:||Influence of consolidation shear stresses and relative density on threshold strain and pore pressure during cyclic straining of saturated sand|
|Authors:||Rensselaer Polytechnic Institute. Department of Civil Engineering.|
Dobry, R. (Ricardo), 1922-
Thomas, Gregory E.
Pierce, William G., 1952-
|Keywords:||Shear strength of soils|
|Publisher:||Geotechnical Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; GL-84-15.|
Abstract: In the last few years, a cyclic strain approach to pore pressure buildup and liquefaction during earthquakes of saturated cohesionless soils has been proposed and developed at Rensselaer Polytechnic Institute (RPI) and at other organizations. One of the key findings has been the existence, for every potentially liquefiable site and sand layer, of a "threshold ground surface acceleration," a𝚝, below which there is no pore pressure buildup. The value of a𝚝 is mainly a function of two soil parameters: the "threshold shear strain" of the sand, ϒ𝚝, and its maximum shear modulus, G𝚖𝚊𝚡. The existence of a𝚝 has been detected by several researchers in a number of laboratory studies. Also, the existence of ϒ𝚝 and its range of values for quartz sands has been predicted from simple particulate mechanics considerations. The work presented herein was performed at RPI and constitutes an extension of the experimental study by Ladd and focuses on the effects of anisotropic consolidation and of very low relative densities on ϒ𝚝 and on the rate of pore pressure buildup at cyclic strains slightly above ϒ𝚝. Two sands, Monterey No. 0 sand and Banding Sand, were tested and the results are reported herein. The effect of anisotropic consolidation is important because NC sands in the field are typically anisotropically consolidated, and also because any attempt to extend the cyclic strain approach to earth structures and slopes must necessarily consider the effect of consolidation shear stresses. Testing very loose sand, D𝚛 = 20 per cent, is important because very loose sand deposits in the field are usually the most susceptible to pore pressure buildup and liquefaction during earthquakes.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Miscellaneous Paper|