Soil arching is a natural phenomenon which occurs in all granular soils as a result ofudstress redistribution. This study investigated the arching mechanism in three sands inuda 1:3 experimental model. The degree of soil arching within an embankment isudassumed to be dependent on a number o f factors such properties of the fill material,udthe fill density and the height of the embankment and three series of tests were carriedudout to determine the effect of these factors on the arching mechanism At slowudsettlement rates load transfer occurred instantaneously and maximum load transferudwas achieved after base displacements o f 3-7mm. A faster rate of settlement of theudsubsoil increased load transfer initially however as settlement continued this loweredudto a residual load transfer similar in magnitude to the load transfer achieved at slowerudsettlement rates.udThe density index and peak and constant value angles of friction were found to beudgoverning factors for load transfer and surface displacements. From the load transferudand displacement data a value for the critical height for each sand was calculated. Theudcritical height was not a constant but was found to be also dependent on theudgeotechnical parameters of the fill material. Base and surface settlements reducedudconsiderably once the height of the fill was above the critical height, He, howeveruddifferential surface settlements were observed in all tests suggesting that zerouddifferential settlement may only be achieved at fill heights significantly greater thatudthe critical height, He.udThe stress reduction ratio, (SRR) was employed to compare the experimental resultsudwith current design methods. The range for the critical height determined from theudmodel tests was found to be in close agreement to those stated in the literature byudTerzaghi (1943), Aslam and Ellis (2008), van Eekelen et al (2003) and Na ughtonud(2007).
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