Abstract: In order to analyze the effect of movement of key neighboring strata on the pressure of longwall mining, and reveal the mechanism of the composite effect of key stratum, failure characteristics of two key neighboring strata and broken law have been studied by using electrical testing technology. And through making the characteristics verified by the pressure data in the test section, the paper has figured out that the stope pressure step is of a big and a small periodical change under the influence of the composite effect of key strata. Thus, the spatial structure model of the type of overlaying strata has been established. According to the structural relationship of key blocks in the model, the support working values of the working faces have been obtained, which have turned out to be in accordance with the measured results, and finally has offered basis of the control of surrounding rock under similar geological conditions.

Key words: key stratum, composite effect, spatial structure, strata behaviors