The Measurement of Pore Water Pressures Adjacent to a Driven Pile

Abstract

Two experiences with the use of a new piezometer are reported. The principle of operation is similar to the Geonor piezometer in that water permeates through a porous membrane. The main difference lies in the method of construction and installation. This instrument was designed for measuring the water pressures adjacent to a driven steel pile. To achieve this, the piezometer is welded to the outside face of the pile and driven with the pile. The installation technique was satisfactory and the instrument is considered successful. A number of different applications and modifications are proposed and these are enumerated briefly. Finally the sensitivity of the instrument is considered in the Appendix.

Foundations on Soft Clay

“…The driving of piles causes high excess pore water pressures which generally increase with increasing shear strength of the clay and with decreasing pile spacing (Bjerrum & Johannessen 1961;Nishida, 1963;Lo & Stermac, 1965;Lo, 1968;Lambe & Horn, 1965 ;Hanna, 1967;Orrje & Broms 1967;Koizumi & Ito, 1967;Clark & Meyerhof, 1972;Torstensson, 1973b). The increase is normally larger for pile groups than for single piles.…”