According to the deep analysis on the formation mechanism of compound rock strata, the mechanical condition of compound rock strata formation and the related formula are obtained to build up the differentiate method of the compound key strata in the coal face strata and the corresponding differentiate program is made.

Using the finite element method to do numerical simulation on the dynamic developmental rule of the abscission layer under the compound key strata, it is discovered that the developmental space rule of abscission layer under the compound key strata presents two phases; the abscission layer before the compound key strata s first collapse mostly distributing in the central section o.

With a specially designed experimental instrument,the mechanism of load transfer within an unconsolidated confined aquifer and its effect on compound breakage of key strata have been studied.

Howevert,he loading transfer effect of separation area water induces compound breakage of two inferior key strata in lower parts,o height of water flowing fracture zone develops abnormally,and it connects separation area water,which is the reason of the 745 working face abnormal water inrush.

With factors such as co-operation between two any terms of part of speech in a sentence and the neighborhood between any two terms of the candidate set,some related words in the candidate set are combined as the compound keywords.

Research on a Compound Keywords Abstraction Based on Small World Network Theory;