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Laboratory study for determining geotechnical engineering properties of cement-treated and-untreared backfill soils used in high speed railway embankments
Formation of high-speed train (HST) infrastructure is a rather new subject worldwide and in Turkey, as HST infrastructure is different than for normal train infrastructure (NTI). Existing NTI remains inadequate to meet high geometric and material properties required by HST. If strict criteria is not met, fatal accidents may occur. In this study; Taiwan HST Project.s design criteria and fill types were used to study replaceability of one fill strata called: Uncemented-Prepared Subgrade Layer (UPSL) with a cemented one (C-PSL) by conducting various laboratory tests to obtain soils. index properties and parameters, which were used to find the maximum total settlements by using Plaxis V8 (2D) Programme. For this purpose; 3 groups (totally 270 no.s with 90 no.s per group) of cylindirical concrete samples were obtained with various cement contents (10, 15, 20, 25, 30 % by weight of concrete) at 3 diameters (4, 8, 10 cm) and for 2 water-cement ratios (0.4, 0.5), then 7-28 day cured and tested at IYTEMAM to find elasticity modulus, stress, strain, force results. Using such results in the Plaxis Programme, maximum total settlements were calculated for different layers. C-CPSL mixes having 20-30% cement contents met the required strict settlement criteria as with the U-PSL mix currently used in Far-Eastern HST Projects. This showed that one of such C-PSL mixes can be used in place of U-PSL with an approximately 12.5 % reduction in the layer thickness, corresponding to 1.75m, instead of 2.0m thickness of the U-PSL currently used. Key Words: Transportation Embankments, High-Speed Train infrastructure, High-Speed Train Fill Properties.