Wave-induced Liquefaction Research Articles

Bedding Types in Holocene Tidal Channel Sequences, Knik Arm, Upper Cook Inlet, Alaska

ABSTRACT Uplifted convoluted and horizontal to subhorizontal beds of varying thickness in intertidal silt as old as 3,280 ± 90 yr B.P. are exposed in the banks of tidal channels of unknown depth in the intertidal zone in Knik Arm of Upper Cook Inlet. Internal discordances may occur both within convoluted beds and between convoluted and horizontal to subhorizontal beds. At the base of many convoluted beds, there is a rapid gradation upward into laminae which are severely deformed; that is, in some places, the contortions appear to have originated along a single bedding plane. Where the convoluted sequences are truncated by nearly horizontal sequences, the distortion must have resulted from syndepositional or postdepositional events prior to their burial by the overlying beds. Various forms of gravitational and tidal processes caused the deformation of the Knik Arm deposits; events triggering the movement of the sediment include any or all of the following: (1) seismic activity, (2) sediment or ice loading, (3) wave-induced liquefaction, (4) pore-pressure changes brought on by changing levels of tidewater, (5) undercutting of sediments by channel migration, and (6) freezing and thawing.

Ocean wave-induced liquefaction analysis : Nataraja, M S; Gill, H S J Geotech Engng Div ASCE, V109, NGT4, April 1983, P573–590

Ocean wave-induced liquefaction analysis : Nataraja, M S; Gill, H S J Geotech Engng Div ASCE, V109, NGT4, April 1983, P573–590

Ocean Wave‐Induced Liquefaction Analysis

Cyclic shear stresses developed below the ocean bottom as a result of a passing wave train may progressively build up pore pressure in certain soils. Such built-up pore pressure may eventually be large enough to result in significant deformation or develop cyclic liquefaction of these soils. A typical ocean wave-induced liquefaction analysis requires data on ocean wave characteristics, geotechnical details of the subbottom soil profiles, cyclic shear stress distribution below the sea bottom resulting from passage of waves, and laboratory test results defining the cyclic shear strength of the liquefiable soils. Analytical and testing methods currently available for performing such analyses are complex, time consuming, generally too expensive, and not correlated with field experience. A simplified procedure has been developed which can be used as a first step to check if a more detailed analysis is warranted. The procedure is examined in the light of four case histories.