Experimental study of the strip coal pillar models failure with different roof and floor conditions

In order to study the failure mechanism and characteristics for strip coal pillars, a monitoring device for strip coal pillar uniaxial compression testing was developed. Compression tests of simulated strip coal pillars with different roof and floor rock types were conducted. Test results show that, with increasing roof and floor strength, compressive strength and elastic modulus of “roof-strip coal pillar-floor” combined specimens increase gradually. Strip coal pillar sample destruction occurs gradually from edge to the interior. First macroscopic failure occurs at the edge of the middle upper portion of the specimen, and then develops towards the corner. Energy accumulation and release cause discontinuous damage in the heterogeneous coal-mass, and the lateral displacement of strip coal pillar shows step and mutation characters. The brittleness and burst tendency of strip coal pillar under hard surrounding rocks are more obvious, stress growth rate decreases, and the rapid growth acoustic emission (AE) signal period can be regarded as a precursor for instability in the strip coal pillar. The above results have certain theoretical value for understanding the failure law and long-term stability of strip coal pillars.