Earth Pressure Cells: Environmental Effects and Calibration

Earth pressures exerted on tall, rigid retaining walls by confined backfill zones are not well understood. Many factors such as: complex soil-structure interaction, soil arching within the backfill, vertical shear transfer, seasonal temperature effects, and variable methods of construction affect the earth pressures. A new monolithic wall for the McAlpine Lock Replacement project of the U.S. Army Corps of Engineers, in Louisville, Kentucky, was instrumented to measure earth pressures and temperatures. Data were collected for two years and continues. Pressures and temperatures were measured for monolith L-11. Construction procedures greatly affected retrieved data. Earth pressure readings were affected by changes in backfill temperature because of thermal expansion∖contraction in the pressure cell oil chamber. A data filtering procedure was developed and subsequently verified through laboratory testing. Data adjusted with this filtering method agreed reasonably well with earth pressures estimated from theory.