Over the past years, considerable advances have been made into the understanding of the behaviour of using geosynthetics to improve the performance of shallow embankments. Detailed investigations have been performed using small scale and large scale models to evaluate their performance and to develop rational methods for design. This document provides a guide to geotechnical engineers who wish to analyse the performances of geogrid reinforcements when installed in different locations of the track structure.

The use of geocells in base reinforcement of structural fill allows confinement of the soil from lateral spreading, therefore preventing shear failure and increasing the soil bearing capacity.Geocell are typically loaded by the live loads on the surface and the overall structure is tensioned while the underlying foundation soil settles. Geocells are regularly used for soil confinement on steep slopes to prevent severe erosion. The geocells are sometimes installed even over slippery geomembranes to contain and reinforce the cover soil.The geocells in these applications should withstand high tensile stresses both in the strands and the junctions without breaking and sliding down the slope. A need for more accurate and specific geocells testing is needed by the design engineers when designing such a critical applications. The testing procedures appropriate for geocells will be investigated, performed and analyzed in this paper. The description of the above tests and some preliminary results are presented and discussed. A final proposal for test standards concerning geocells will be presented for consideration by the existing geosynthetics testing committees.

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A 15 m high green faced reinforced slope was built in 1996 to stabilise a landslide situated on the Montone hill in the province of Perugia (Italy). The reinforced slope was built using locally available soils as fill material and HDPE mono-oriented extruded geogrids as reinforcement. The reinforced slope has been instrumented with strain gages connected to the reinforcing geogrids and with total pressure cells; full scale in situ pull-out tests have been performed as well. The preliminary results demonstrate the good performance of the geogrids and define possible failure mechanisms for slopes with stepped geometry. The in situ pull-out test results validate laboratory tests performed in the past. To evaluate the field stress and deformation behavior of the reinforced slope a finite element analysis has been carried out. The paper describes the model technique developed to evaluate the field stress and deformation of steep reinforced slope using special interface elements. The results of finite element analysis are in agreement with the field measured results.