Earthquake response and sliding displacement of submarine sensitive clay slopes

Abstract Many submarine landslides occur through marine sensitive clay layers, and the strain softening behavior plays a key role. The changing soil properties induced by various disturbances will have marked impact on earthquake performance of submarine clay slopes. In the present study, undrained triaxial compression tests on reconsolidated samples of a soft sensitive marine clay were conducted, and a soil disturbance dependent simple constitutive model is proposed for describing post-peak nonlinear strain softening behavior of sensitive clays based on experimental results, and then is implemented in QUIVER code to perform one-dimensional seismic response analysis of mild infinite slopes, to address the relative importance of soil disturbance effect on the site response and sliding displacement of submerged slopes during seismic loading. Detailed laboratory test descriptions and results of a soft sensitive marine clay, model formulations and comprehensive computational efforts are presented. Parametric study of site response analysis focusing on the effects of soil disturbance degree and depth on generic clay grounds with varying sloping angles subjected to harmonic and earthquake loadings are performed. The predicted acceleration amplification, maximum shear strains and permanent displacements provide insight of earthquake performance of submarine sensitive clay slopes. The main findings are drawn based on several key concepts. First, undisturbed sensitive clay is typically stiffer and stronger than disturbed clay consolidated at the same stress level and hence, unless strain softening is triggered, structured sensitive clay will perform better than insensitive clay of the same residual strength. Second, post-peak softening at shallow depth will lead to strain localization on a thin layer, which is the main cause of sudden change of upward wave propagation characteristics and large permanent displacement at seabed surface of mild submarine clay slope. Thirdly, soil disturbance degrees and depths have very marked effects on seismic response and displacement performance of sensitive clay slopes, and such effect will be further enhanced by slope angle or earthquake intensity, which should be cautiously treated in engineering design.

[1]  R. Kayen,et al.  Varieties of submarine failure morphologies of seismically-induced landslides in Alaskan fjords , 2006 .

[2]  F. Nadim,et al.  Some important considerations in analysis of earthquake-induced landslides , 2016, Geoenvironmental Disasters.

[3]  Hideo Hanzawa.  UNDRAINED STRENGTH CHARACTERISTICS OF NORMALLY CONSOLIDATED AGED CLAY , 1983 .

[5]  Jonathan P. Stewart,et al.  Simplified Model for Small-Strain Nonlinearity and Strength in 1D Seismic Site Response Analysis , 2016 .

[6]  S. Leroueil,et al.  Behaviour of the stiff and sensitive Saint-Jean- Vianney clay in intact, destructured, and remoulded conditions , 2002 .

[7]  G. Pedersen,et al.  Submarine landslides: processes, triggers and hazard prediction , 2006, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[8]  Chang-Yu Ou,et al.  Failure Investigation at a Collapsed Deep Excavation in Very Sensitive Organic Soft Clay , 2015 .

[9]  Nabil Sultan,et al.  The 1979 Nice harbour catastrophe revisited: Trigger mechanism inferred from geotechnical measurements and numerical modelling , 2007 .

[10]  G. Biscontin,et al.  Seismic triggering of submarine slides in soft cohesive soil deposits , 2004 .

[11]  David M. Boore,et al.  Estimating V̄s(30) (or NEHRP Site Classes) from Shallow Velocity Models (Depths < 30 m) , 2004 .

[12]  A. W. Skemption,et al.  The Sensitivity of Clays , 1952 .

[13]  G. Biscontin,et al.  Factors affecting seismic response of submarine slopes , 2006 .

[14]  Mark Randolph,et al.  Recent advances in offshore geotechnics for deep water oil and gas developments , 2011 .

[15]  Gokhan Saygili,et al.  Probabilistically based seismic landslide hazard maps: An application in Southern California , 2009 .

[16]  Tom Lunne,et al.  Effects of sample disturbance and consolidation procedures on measured shear strength of soft marine Norwegian clays , 2006 .

[17]  N. Newmark.  Effects of Earthquakes on Dams and Embankments , 1965 .

[18]  De’an Sun,et al.  Hydromechanical behaviour of expansive soils with different suctions and suction histories , 2016 .

[19]  R. Boulanger,et al.  Nonlinear deformation analyses of an embankment dam on a spatially variable liquefiable deposit , 2016 .

[20]  Jonathan D. Bray,et al.  NONLINEAR COUPLED SEISMIC SLIDING ANALYSIS OF EARTH STRUCTURES , 2000 .

[21]  Takeshi Matsumoto,et al.  Architecture and Failure Mechanism of the Offshore Slump Responsible For the 1998 Papua New Guinea Tsunami , 2003 .

[22]  R. Jardine,et al.  Assessing Well Drilling Disturbance Effects on Offshore Foundation Piles in Clay , 2008 .

[23]  L. Germanovich,et al.  The growth of shear bands in the catastrophic failure of soils , 2005, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[24]  M. Randolph.  Offshore Geotechnics - The Challenges of Deepwater Soft Sediments , 2012 .

[25]  Pierre Cochonat,et al.  Investigation of a possible submarine landslide at the Var delta front (Nice continental slope, southeast France) , 2010 .

[26]  B. Kutter,et al.  Static and seismic stability of sensitive clay slopes , 2015 .

[27]  Jonathan D. Bray,et al.  An Empirical Geotechnical Seismic Site Response Procedure , 2001 .

[28]  K. Soga,et al.  Numerical modelling of submarine landslides with sensitive clay layers , 2016 .

[29]  Nathan M. Newmark,et al.  A Method of Computation for Structural Dynamics , 1959 .

[30]  Site Response, Shallow Shear-Wave Velocity, and Damage in Los Gatos, California, from the 1989 Loma Prieta Earthquake , 2001 .

[31]  Jonathan D. Bray,et al.  Simplified Procedure for Estimating Earthquake-Induced Deviatoric Slope Displacements , 2007 .

[32]  S. Leroueil,et al.  Weak Layers: Their Definition and Classification from a Geotechnical Perspective , 2014 .

[33]  M. J. Hvorslev.  PHYSICAL COMPONENTS OF THE SHEAR STRENGTH OF SATURATED CLAYS , 1960 .

[34]  J. Germaine,et al.  Stress Dependence of Shear Strength in Fine-Grained Soils and Correlations with Liquid Limit , 2013 .

[35]  R. Kayen,et al.  Pleistocene slope instability of gas hydrate‐laden sediment on the Beaufort sea margin , 1991 .

[37]  Ross W. Boulanger,et al.  Shear Localization Due to Liquefaction-Induced Void Redistribution in a Layered Infinite Slope , 2006 .

[38]  D. Gunn,et al.  Predicting variability in the stability of slope sediments due to earthquake ground motion in the AFEN area of the western UK continental shelf , 2004 .

[39]  D. Wood.  Soil Behaviour and Critical State Soil Mechanics , 1991 .

[40]  Farrokh Nadim,et al.  Seismic Triggering of Submarine Slides , 2007 .

[41]  P. Bryn,et al.  The Storegga slide: evaluation of triggering sources and slide mechanics , 2005 .

[42]  B. Bornhold,et al.  The Grand Banks landslide-generated tsunami of November 18, 1929: preliminary analysis and numerical modeling , 2005 .

[43]  John T. Germaine,et al.  Sampling Disturbance Effects in Normally Consolidated Clays , 2002 .

[44]  R. Popescu,et al.  Finite element simulation of seismically induced retrogressive failure of submarine slopes , 2005 .

[45]  G. Saygili,et al.  Predictive Models for Earthquake Response of Clay and Sensitive Clay Slopes , 2014 .

[46]  K. Soga,et al.  Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis , 2016 .

[47]  E. Kavazanjian,et al.  Seismic stability of gentle infinite slopes , 1985 .

[48]  Gokhan Saygili,et al.  Empirical Predictive Models for Earthquake-Induced Sliding Displacements of Slopes , 2008 .

[49]  Bruce L. Kutter.  Earthquake Deformation of Centrifuge Model Banks , 1984 .

[50]  Thomas C. Sheahan,et al.  Rate-Dependent Undrained Shear Behavior of Saturated Clay , 1996 .

[51]  M. Romo.  Clay Behavior, Ground Response and Soil-Structure Interaction Studies in Mexico City , 1995 .

[52]  R. Jardine,et al.  Evaluation of Geotechnical Parameters from Triaxial Tests on Offshore Clay , 1985 .

[53]  C. Ladd,et al.  THE INFLUENCE OF STRESS SYSTEM ON THE BEHAVIOR OF SATURATED CLAYS DURING UNDRAINED SHEAR , 1965 .

[54]  Robb E.S. Moss,et al.  Quantifying Measurement Uncertainty of Thirty-Meter Shear-Wave Velocity , 2008 .

[55]  Juan Acosta,et al.  Shallow slides and pockmark swarms in the Eivissa Channel, western Mediterranean Sea , 2004 .

[56]  R. Jibson.  Regression models for estimating coseismic landslide displacement , 2007 .

[57]  Thomas C. Sheahan,et al.  Application of Recent Developments in Terrestrial Soft Sediment Characterization Methods to Offshore Environments , 2007 .