People
Pedro deAlba
Ph.D. University of California at Berkeley, 1975
- Professor of Civil Engineering
Research Areas
Earthquake engineering, foundation design, soil mechanics
Research Emphasis
When a sand which is saturated is shaken by earthquake loads, it "liquefies" which means that it temporarily loses a large proportion of its strength. Earthquakes can produce high-velocity liquefaction flow slides in slopes of saturated sandy soils; they can occur in both constructed embankments such as earth dams and in natural slopes. Such slides have produced a great deal of damage during earthquakes and, more importantly, considerable loss of life. For example, over 600 people died when their neighborhoods were buried by landslides during the 2001 earthquake in El Salvador. Professor Tom Ballestero (CiE) and I are trying to model liquefied sand as a viscous fluid by measuring the behavior of spheres and plates falling through liquefied sand in the lab. If we can model liquefied sands in this way, it should be possible to predict how these sands will behave after they liquefy, and how far they will 'run out' during sliding. These studies are relevant to ocean engineering, because earthquake- induced flow slides (also known as ‘turbidity currents’) occur offshore, for example the flow slide produced by the 1929 Grand Banks earthquake, which in turn produced a tsunami causing 27 fatalities and extensive damage in Newfoundland.
I am also interested in earthquake effects on port facilities. From a civil engineering viewpoint, wharves are really complicated structures, quite top-heavy because of large cranes, and usually supported on piles through very weak liquefiable soils. Earthquake impact studies for West Coast ports show that a large part of the economic losses will come from damage to cargo-handling structures, but it’s currently hard to predict how they will behave during earthquakes. We need more information from model and field studies to improve our analysis tools.