Geotextile Encased Columns (GEC) under bridge approaches as a pressure-relief system: Concept, experience, measurements
Geosynthetic Encased Sand Columns (GEC) have been frequently adopted in geoengineering practice to improve bearing capacity, reduce settlements and accelerate consolidation in saturated soft cohesive ground. The present paper extends these early views by introducing the use of columns to reduce the magnitude of horizontal earth pressures acting on structures adjacent to compaction fills. The monitoring program of a full-scale bridge abutment on soft soil supported by GECs and geogrid reinforced system is described and field performance was monitored with pressure cells, electrical piezometers, inclinometers and settlement plates. The collected database is interpreted in order to estimate the horizontal earth pressure over bridge border foundation piles.
The present paper discusses the use of Geosynthetic Encased Sand Columns installed on soft soils to reduce the magnitude of horizontal earth pressures acting on a bridge structure adjacent to an 8m high compaction fill. Construction work has been comprehensively monitored with pressure cells, electrical piezometers, inclinometers and settlement plates in order to evaluate the load transfer mechanism taking place in the soft clay layer. Sand columns have proven to be useful in providing drainage to reduce the potential for build up of excess pore water pressures in the clay layer, in reducing the magnitude of settlements and in reducing the maximum horizontal earth pressure acting on structures adjacent to compacted fills.