Stand Alone and Combined Technologies for MSE Walls: State of Practice for Compressible Soils

The need for modifications to Mechanically Stabilized Earth (MSE) supported over compressible soil conditions is commonly misunderstood by those that are unfamiliar with the inherent flexibility of the wall system. Conventional MSE walls consist of precast concrete facing panels with either steel or geosynthetic reinforcements in a compacted granular backfill matrix, which may be used in locations of relatively high differential settlements approaching 1%. Total settlements alone do not discount use of MSE walls, with some documented projects exceeding 1000 mm in settlement. This paper will address the design, construction and monitoring aspects of MSE walls over highly compressible soils. Brief descriptions of phased and staged construction techniques will be followed by a discussion of ground improvement measures that have gained acceptance in MSE wall support. The significant design issue of a transition zone will be discussed as a part in distribution of loading from the MSE wall to supporting ground improvement measures. Case examples will be provided to demonstrate the important interaction needed from design to construction.