ASCE G-I Case History Night, April 28, 2016 Seismic Earth Pressure Variations in Retaining Walls with Cohesive Backfill Material Siavash Zamiran, Abdolreza Osouli Civil Engineering Department April 28, 2016

Outline Conducting numerical models to evaluate seismic earth pressure Using finite difference method, FLAC software Assuming soil cohesion for backfill Assuming soil-wall adhesion Considering different earthquake loading Considering hysteretic behavior of soil Calibrating of the model with centrifuge tests conducted by Agusti and Sitar, 2013

Failures of Retaining Walls Due to Earthquake Caused by Kobe Earthquake in 1995

Failures of Retaining Walls Due to Earthquake Loading Caused by Mid-Niigata Prefecture Earthquake in 2004

Seismic hazard map of the USA Reference: United States Geological Survey

New Madrid seismic zone Reference: United States Geological Survey

Analytical methods

Some of the analytical methods which consider backfill cohesion

Centrifuge Model Based on study by Agusti and Sitar, 2013 Seismic earth pressure on retaining structures in cohesive soils UC Berkeley Sponsored by California Department of Transportation

Numerical Modeling Geometry

Soil Properties Constitutive model: UBCHYST Soil type: low plasticity lean clay (CL), called Yolo Loam from a borrow pit at the centrifuge facility Density= 2038.7 kg/m3

Interaction of Wall and Soil

Computer simulation of retaining wall

ACCELERATION AND DISPLACEMENT HISTORY Kobe Kocaeli

Seismic earth pressure coefficient versus free field acceleration

Study phases in progress Effect of strength properties: cohesion and friction angle Effect of different earthquakes Effect of earthquake intensities Effect of wall rigidity Effect of soil-wall interaction Effect of backfill saturation

Analyzing the responses Seismic earth pressure approach Analytical: Mononobe-Okabe, Shukla, etc, DOTs Displacement approach Analytical: Newmark method, AASHTO

Fragility analysis Based on methodology developed by Argyroudis et. al, NIT, (2013) Development of fragility functions for geotechnical constructions: Application to cantilever retaining walls Definition of damage states Numerical modeling, estimation of deformation based on PGA Probability of damage VS PGA

Workshops held in SIUE: Introduction to Computational Geotechnics, Jan 2016 Numerical Modeling of Foundations Using FLAC3D, Jan 2015 Underground Coal Mine Stability Analysis , Jan 2015 Numerical Modeling in Geotechnical Engineering 2, Oct 2014 Numerical Modeling in Geotechnical Engineering 1, Aug 2014

Introduction to Computational Geotechnics, Jan 2016

Numerical Modeling in Geotechnical Engineering, Oct 2014

Thank you. Questions?

References Agusti, G. C., & Sitar, N. (2013). Seismic Earth Pressures on Retaining Structures in Cohesive Soils (No. UCB GT 13-02). California Department of Transportation. Argyroudis, S., Kaynia, A. M., & Pitilakis, K. (2013). Development of fragility functions for geotechnical constructions: Application to cantilever retaining walls. Soil Dynamics and Earthquake Engineering, 50, 106–116. Shukla, S. K., Gupta, S. K., & Sivakugan, N. (2009). Active Earth Pressure on Retaining Wall for c-ϕ Soil Backfill under Seismic Loading Condition. Journal of Geotechnical and Geoenvironmental Engineering, 135(5), 690–696. Mononobe, N., & Matsuo, H. (1929). On the Determination of Earth Pressures During Earthquakes. In World Engineering Congress 9 (pp. 177–185).