Full Scale Trial Embankment Test—Acceleration of Consolidation Using the Rammed Aggregate Pier (RAP) System

A full scale instrumented trial embankment test was conducted to evaluate the effects of the Rammed Aggregate Pier (RAP) System on the very soft clays underlying railway a proposed embankment test site in the island of Luzon, the Philippines. A 5.0m high trial embankment was on a Section of a 10 kilometer stretch of railway on relatively very soft marshy ground to simulate embankment loads and the impact of train loads on railway embankments of the NORTHRAIL Railway. The study was initiated to prove that consolidation time in very soft clays could be accelerated by the lateral prestressing and prestraining effects of the rammed aggregates piers on the subgrade and the enhanced drainage effect of the RAP body. This paper discusses the test embankment construction, instrumentation and monitoring and the geotechnical exploration to gather soil parameters. The theoretical settlement calculations and field observations served as the bases for the findings reported. The results of the settlement monitoring program revealed that significant time savings could be realized during railway embankment construction if the RAP System is utilized, because time to full consolidation was accelerated to four (4) weeks instead of the calculated 6 to 8 months using other conventional ground improvement systems.