The Use of the Enviro-Wall-Mat in Soft Soil Conditions for Marshalling Areas, Crane Hard Stands and Lay Down Areas

Heavy Duty Pavements B.V. (HDP) and Geobest B.V. are in the process of developing a new concept, named ”the Enviro Wall-Mat”. This concept is based upon the successfully adopted Enviro-Mat stabilisation, combined with a Trench Formed Wall (TFW).  The Enviro-Mat is realised by in situ mixing of (local) soil, cement and an additive at ground level. In this way a stabilized layer is created with a low carbon footprint as local soil is used. The Trench Formed Wall is created by means of a deep trenching machine, that creates a trench with a maximum depth of 15 m. The outcoming soil is transported to ground level and the trench can be simultaneously filled with a low strength slurry that is mixed on surface level.  By combining both techniques, a fully supported stabilised layer can be created that is capable to withstand high and irregular loads even in very compressible soils. The Enviro-Walls act therefore as a deep foundation for the Enviro-Mat when a tip level in sand layers is chosen. As an alternative, a higher tip level may be chosen. In this case, the walls act as a settlement reducing solution, that can be compared to a raft foundation.  The concept has first been analysed by means of finite element calculations with program Plaxis 3D. The conclusion was that the concept should be feasible. Based on these positive results, it was decided to perform a full scale load test. This test was performed in August 2021. This paper describes the result of this test and the associated Plaxis analyses.