The research objective of this Faculty Early Career Development (CAREER) project is to improve understanding of the seismic behavior of slickensided surfaces in fine-grained soils. This will be achieved while actively engaging undergraduate students through a service-learning outreach program focused on engineering reconnaissance in the aftermath of natural disasters. ?Slickensided surfaces? are planes of weakness formed in stiff clays due to large shear displacements concentrated on a landslide slip surface. Slickensided surfaces are commonly encountered in clay shale or overconsolidated clay slopes. Their low strength is a significant source of slope stability problems. Although slickensided slopes and the structures they support may be stable under static load conditions, movement along pre-existing slickensided rupture surfaces can represent a critical mechanism for sliding during earthquakes. Little information is currently available concerning the shearing resistance that can be mobilized along pre-existing slickensided rupture surfaces under seismic loading conditions.
To address this lack of understanding, the PI will develop a unique torsional shear device that will be used to form slickensided shear planes in clay soils, and to measure the static and cyclic shear strengths along these slickensided surfaces. This device will be used to test a wide variety of pure clay minerals and natural clay soils to develop a fundamental understanding of the seismic behavior of slickensided shear surfaces. Additional testing will also be performed to determine the relationship between soil pore pressures and the measured dynamic strengths, to examine the effects of pore water chemistry on soil shear behavior, and to evaluate the post-shaking static shear strengths.
An integrated education plan will support the PI?s research efforts through the development of a unique service-learning and outreach program: DElaware Students Engineering in response to Natural Disasters (DE-SEND). DE-SEND will be comprised of a volunteer cadre of undergraduate students that will mobilize following natural disasters to perform rapid engineering reconnaissance. DE-SEND students will perform: 1) senior thesis projects to analyze and disseminate data gathered during reconnaissance efforts, 2) senior design projects to solve natural-disaster-related problems, and 3) outreach efforts to local undergraduate student organizations and K-12 schools. Students will also collect and analyze soil samples to support the PI?s on-going research efforts.
Improved knowledge of the development and properties of slickensides will lead to improvements in the seismic analyses of clay slopes and to improved understanding of the skin friction on driven piles. The PI?s educational goal is focused on developing a new, non-traditional learning environment outside the classroom (DE-SEND). This endeavor presents a unique opportunity to ?bring the students to the problem,? to excite them about engineering using a novel approach. Observing catastrophic engineering failures caused by natural disasters will be an eye-opening experience for many undergraduate students, and is an ideal educational opportunity for training the next generation of civil engineers.
