Instrumentation for Test Fill in Hong Kong

Abstract

An offshore test fill was constructed over very soft marine clay to help develop and prove construction techniques for a large proposed reclamation project. The fill and foundation soils were heavily instrumented to monitor their performance during and after construction. The instrumentation was used to measure the rate and amount of settlements, lateral movements, and excess pore pressures. It consisted of pneumatic and hydraulic piezometers, settlement plates and pipes, pneumatic settlement gages, inclinometers, subsurface settlement anchors, and surface movement points. Two major constraints of the instrumentation program were the large vertical strains (approximately 40%) anticipated and the need for overwater/underwater installation of many of the instruments. Special installation and protection measures were developed to overcome these constraints. Performance aspects of the instruments are discussed and typical plots of the data are presented. Additional field testing was undertaken during the monitoring period to verify and supplement the data being obtained from the instruments. This testing is discussed briefly.