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采用分级增量循环加卸载方式,对湖南湘煤集团牛马司矿业公司水井头煤矿-300m东大巷二煤层底板粉砂岩进行了单轴蠕变特性试验,探讨了轴向蠕变和各蠕变阶段的非线性粘弹塑性变形特征。试验结果表明,当应力水平低于岩石的长期强度时,粉砂岩只发生衰减蠕变;瞬时塑性应变和粘塑应变随轴向应力的增大而增大,瞬时弹性模量随应力水平增大而增加,而变形模量随应力水平增大和时间的增长逐渐减小,直至趋于某一稳定值;随着应力水平增大,粘弹性应变、粘塑性应变和总蠕变均先减小然后增大,表明低应力下因岩石内部微裂纹不断压密产生应变硬化,高应力下因岩石材料性质不断劣化产生内部损伤发生应变软化。
The uniaxial creep test of the coal seam floor siltstone of the -300m East Main Road of Shuitoushe Coal Mine in Hunan Xiang Coal Group Company was carried out by using incremental incremental loading and unloading method. The axial creep and creep Nonlinear Viscoelastic and Plastic Deformation Characteristics of Stages. The experimental results show that when the stress level is lower than the long-term strength of the rock, only the decay creep occurs in the siltstone. The instantaneous plastic strain and the visco-plastic strain increase with the axial stress, and the instantaneous elastic modulus increases with the stress level While the deformation modulus decreases with the increase of stress level and the increase of time until it reaches a certain stable value. As the stress level increases, the viscoelastic strain, viscoplastic strain and total creep decrease first Increase, indicating that low stress due to micro-cracks within the rock continue to produce strain hardening, high stress due to the continuous deterioration of the nature of the rock material to produce internal damage strain softening.