Determination of loading mechanical characteristics of in-situ tectonic coal

Abstract

Based on the cold forming theory, taking density and permeability as indicators, a high-pressure cyclic loading and unloading method was used to prepare a standard coal briquette with a degree of compaction similar to that of underground in-situ tectonic coal. Based on this coal standard sample, a triaxial press was used to compare the loading mechanical characteristics of the in-situ tectonic coal, and the stress and strain characteristics of the coal body, basic mechanical parameters, and damage and failure modes were obtained. The measurement results show that: compared with intact coal, the stress drop phenomenon of tectonic coal in the post-peak stage is not obvious, showing ideal plastic characteristics; at the same time, the elastic modulus and cohesion are only 15.50% and 26.50% of intact coal, and it is resistant to deformation. The ability is weak and the mechanical strength is low; in addition, the particle aggregate properties of tectonic coal make its post-peak damage mode fundamentally different from that of intact coal. Tectonic coal undergoes multiple shear damage, and the damaged coal body shows pulverization characteristics.

Keywords

• tectonic coal
• conventional triaxial loading
• deformation characteristics
• strength characteristics
• damage failure