急速卸压条件下构造煤体应力释放规律试验研究

Study on stress release law of tectonic coal under rapid unloading confining pressure

为研究构造煤在急速卸压条件下的应力释放规律,开展了不同卸围压速度条件下的型煤试样三轴试验,对比分析了构造煤在不同应力路径下的应力⁃应变曲线和力学特性演化特征,并通过数据拟合分析了急速卸压条件下的应力释放规律。结果表明:卸围压速度越快,构造煤破坏时的变形程度和峰值应力越小。卸围压降低了煤体的内聚力,劣化程度为14.02%~21.95%,卸围压速度越快,劣化作用越强。卸围压降低了煤体变形模量和泊松比,表明卸围压加剧了煤体损伤,降低了煤体抵抗变形的能力。当卸围压速度趋近于急速时,峰值应力的劣化程度为17.84%,内聚力的劣化程度为21.95%,表明急速卸压条件下构造煤更易失稳破坏,应力释放控制瓦斯膨胀能的非稳态释放,从而导致构造煤突出的连续发展。

In order to study the stress release law of tectonic coal in the rapid unloading confining pressure,the triaxial tests of coal specimens under different unloading confining pressure rates are carried out.The characteristics of stress⁃strain curve and the mechanical properties of tectonic coal under different unloading confining pressure rates are compared and analyzed,and the stress release law under the condition of rapid unloading confining pressure is analyzed by fitting the test data.The results demonstrate that the higher the unloading confining pressure rate,the smaller the degree of deformation and peak stress when the tectonic coal is damaged.The unloading confining pressure reduces the cohesion of the coal,with the degree of deterioration being 14.02%-21.95%.The higher the unloading confining pressure rate,the stronger the deterioration effect.The unloading confining pressure reduces the deformation modulus and Poisson's ratio of the coal,revealing that the unloading confining pressure aggravates the damage of the coal and coal to resist deformation are reduced.When the unloading confining pressure rate becomes high,the degradation degree of peak stress is 17.84%and the degradation degree of cohesion is 21.95%.In the rapid unloading confining pressure,it is easy for the tectonic coal to destabilize,and the stress release controls the non⁃stationary release of gas expansion energy,thus leading to the continuous development of tectonic coal outburst.