Major technical modifications to SDJ218-84 include:1 The applicable scope of this standard is changed;2 A new calculating method of dam height (the vertical distance from the foundation elevation to the dam crest at the dam axis) is added;3 A chapter of major terms is added;4 New criteria of compaction for cohesive soil areadded;5 Calculation of wave runup on slopes with a gradient more than 1:1.5 is added;6 The calculating method of curtain thickness according to allowable seepage gradient isdeleted for bedrock grouting;etc.