Embankment Pore Pressures During Construction

Theoretical methods for predicting pore pressures in earth dams are reviewed, and observed pore pressure data from selected dams constructed by the Corps of Engineers (CE) and other agencies are summarized to indicate the development and magnitudes of construction pore water pressures in earth dams. Construction characteristics and pore pressure data from 10 CE dams, 24 USBR dams, and 9 foreign dams are summarized and compared. The study determined that because of the numerous factors which influence pore pressure buildup, broad conclusions for all earth dams are difficult to make and each dam must be treated individually with respect to predicting construction pore pressures. It is concluded that: (1) Provisions for internal drainage effectively relieve construction pore pressures in earth embankments; (2) pore-pressure ratios in embankment materials increase rapidly as placement-water content increases, especially above optimum water content; and (3) pore pressures increase with increasing dam height, but even low dams (less than 100-ft high) can develop large pore pressures.