Publication Date

Spring 2018

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

Advisor

Yogesh Prashar

Subject Areas

Civil engineering

Abstract

The East Bay Municipal Utility District provides water to the eastern region of the San Francisco Bay Area. Water is delivered through the Mokelumne Aqueduct, which consists of three large diameter steel pipelines. Approximately 15 miles of the aqueducts cross the fragile Sacramento-San Joaquin Delta. A stability analysis has been conducted to evaluate how resilient the elevated aqueduct is in the Delta. Subsidence in the Delta considerably reduces the lateral support of piles. Based on previous studies, and available survey and LiDAR data, the amount of subsidence in the Delta has been predicted over time. In addition, site-specific seismic studies have been considered in order to estimate strong ground motion parameters. A series of axial single pile analyses, lateral single pile analyses, and pile group analyses have been performed to quantify the impact of ground loss due to subsidence on pile capacities along the 15-mile alignment. Results were compared with both the maximum expected lateral load at the pile cap occurring due to seismic ground motion (base shear) and the lateral capacity at the 1-inch horizontal displacement of the pile cap (threshold). Analysis shows a significant reduction in the piles’ lateral and axial capacities, caused by lack of soil shear strength. The analytical studies are presented and discussed in order to develop retrofit alternatives.

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