Distribution And Application Of Floor Deviatoric Stress Tensor Invariants Under Close-distance Multiple Pillars

In order to study the effect of coal pillars near the upper floor, Tang Shangou coal mine neardistance coal seam8#,11#,12#,13#, with the average distance is20.33m,20.43m,4.85m, waschosen as the research object. The spatial features of coal pillars group was analyzed with thecondition that8#and11#had been mined. Besides, by selecting the second and third deviatoricstress invariants that could reflect shear stress, distortion energy and strain types of medium asjudgment index, the influence came from different coal pillar width, low horizontal stress, highhorizontal stress and mining thickness, center distance of upper&lower and horizontal double coalpillars to second deviatoric stress invariants (shear stress, distortion energy) and third deviatoricstress invariants (tensile strain, compressive strain and plane strain) were researched. Specially, thefloor mechanical response features affected by coal pillars group was newly understood from theperspective of shear stress, distortion energy and strain types. And the industrial test was conductedin the meantime. Furthermore, the one-sidedness that the more achievements usually took theabutment pressure (vertical pressure) as single measuring index，which is a component force.It isbelieved that change relation of every component force is the scientific reason to different minepressure，which enrich the theory of ground pressure.