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"While there is considerable work to be <br />done, past experience also suggests that <br />many of these wall types have performed <br />well during relatively high seismic loading, <br />despite having either no provisions for <br />seismic design or a very simple analysis. In <br />most cases this good performance <br />occurred when walls were flexible or <br />exhibited considerable ductility." <br />"Soil nail walls can be treated as semi - <br />gravity walls from an external stability <br />standpoint. In most cases seismic <br />coefficients can be reduced by 0.5 since <br />this type of wall can usually tolerate <br />several inches of permanent movement. <br />For internal stability there are still <br />questions on the distribution of seismic <br />forces to the nails within the reinforced <br />zone and whether the current models <br />adequately accountfor these <br />distributions. Additional research is still <br />required to evaluate these questions." <br />The current state of practice in soil nail <br />wall design is to apply seismic loading for <br />only external stability, which we did in our <br />design. Therefore, in our opinion, seismic <br />loading should not be applied internally to <br />soil nail walls, which is consistent with the <br />current Standard of Practice as set forth <br />by AASHTO/FHWA. <br />4 <br />MSE Wall <br />Sheet W1 shows typical wall sections with an alternate <br />sloping toe condition and increased embedment depth of 24 <br />inches. The minimum distance(s) and maximum slope(s) of <br />the toe cover should be specified. See also the TESC <br />construction drawings indicating steep toe slopes at multiple <br />locations. <br />Page 5 of 7 <br />