| Mechanics tests of Jianxin Coal Mine NO. 13 coal seam are studied on MTS815. 03 Electro-hydraulic Servo-controlled Rock Mechanics Testing System. Based on unaxial compressive test, its mechanics parameters measured; the peak section of whole stress-strain curve is relatively placidity, and after the high stress persistence, the coal sample is destroyed rapidly; the size effect can be expressed as σc= 6.928 + 130.2698exp(-0.10595D), and the strength of standardcylinder sample is higher then that of standard cube sample. Based on triaxial compressive test, the character is discussed of that stabilization-lost firstly and re-stabilization of coal' inner-structure under fluid-static pressure; the closed section of whole stress strain curve under triaxial compressive is not obviously and even disappears; coal turns into sheared destroying as confining pressure increases, but the critical confining pressure from brittleness into ductility of Jianxin Coal Mine NO. 13 coal seam is more higher then its unaxial compressive strength; the relation between elasticity module and confiningcompression can be expressed as E = 4955.984-3589.106exp theinfluence of confining compression on strength of coal is very obviously, which is said that the axial destroying stress and last strength increase also as the confining pressure increases; based on Coulomb' law, the relation between largest direct stress different and confining compression is thatσ1-σ3 =9.71005 + 12.4716σ3. Based on rheology test, the rheology character isstudied, the coal is destroyed in integer and it is space asymmetrical; under the higher stress, two kinds of micro- breakage occur in the sample; the rheology is expressed by multinomial as that of ε(t) = 0.00551 + (2.033E-5)*t-(9.754E-8)*t2-(1.578E-9)*t3+(1.417E-11)*t4 .Based on existed theory and test studying result, the chronically unaxial compressive strength is 2. 7088MPa, and it accords with the Mohr-coulomb model. |
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