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The Port of Houston had plans to deepen the existing ship channel to accommodate larger vessels. The new channel depths and the accompanying deepening of the existing berths at the Manchester 2 & 3 Wharfs may undermine their pile foundations. LCR&A performed analytical studies of the existing and proposed wharf conditions to assess the likelihood of a foundation failure after the dredging. The existing foundation system in Manchester 2 Wharf consisted of about 2000 original timber piles of various penetrations mostly installed in 1921, but some new ones replaced and/or reinforced during a major structural strengthening in 1948. The upper structural system had a combination of the original pile cap and a new reinforced concrete system that was built during the major work of 1948.
As a practical solution, LCR&A recommended, designed and implemented a series of sensors and monitoring system to assess the continuity of the structure and the degree of fixity of the piles to the superstructure. The idea was to compare measurements with refinements of a finite element analysis (FEA) model to calculate and match the natural vibration modes for the Manchester 2 Wharf. The goal of the ambient vibration monitoring study was to determine the first four resonant frequencies of the Wharf structure. The instrumentation consisted of five horizontal geophones, designed for the estimated ambient response of the structure and placed in locations that will help to determine the first four modes of vibrations. All measurements were recorded automatically and later retrieved from the site. Various types of analytical tools were developed and used by LCR&A to interpret the resonant frequencies in the time domain under various conditions and positions of the sensors.