分级恒定荷载作用下的煤体变形及内部损伤特性

Deformation and internal damage properties of coal under hierarchical constant load

以鸡西某矿煤样为研究对象,利用电液伺服岩石流变实验系统和声发射系统,研究煤体蠕变特性、内部损伤演化过程及两者之间的关系。研究表明:不同应力下,煤体呈现不同的蠕变特征,实验蠕变曲线与拟合蠕变曲线比较吻合。煤体在每级荷载作用下的声发射振铃计数及能量增长趋势均呈加速、减速和稳速。在此三阶段中声发射信息产生的速率和总数均逐级增加,与煤体纵向变形特征呈现一致性。RFPA模拟煤体蠕变破坏得出,在低应力作用下,煤体表现出衰减性蠕变特性。当应力超过某一值时,煤体表现出稳定蠕变特性,应力越大,蠕变时间越短,AE计数越多。煤体在蠕变过程中产生的声发射信息与其受力、变形及其内部损伤均呈一致性。该研究能较好的揭示煤体在蠕变过程中的变形以及内部损伤演化状况。

This paper investigates the creep deformation characteristics,the internal damage evolution process,and the relationship between them by employing the coal samples from Jixi mine and applying the experimental system of electrohydraulic servo rock rheology and acoustic emission system.The study shows that different characteristics occur in creep deformation of coal under different stress,pointing to the better consistency between the experimental creep curve and the fitted creep curve.Acceleration increase,deceleration increase,and steady increase are present in the acoustic emission ringing counts and energy growth trend of the coal under each level of load.These three stages see the generated rate and total amount of AE information increase step by step,showing the consistency with the longitudinal deformation characteristics of coal body.As is shown by the RFPA simulation of coal creep failure,the coal body under the action of the lower stress is characterized by decay creep and the coal body under the stress exceeding a certain value assumes such a stable creep characteristics that the larger the stress is,the shorter the creep time is and the more AE count is.The consistency exists between the acoustic emission information produced in the process of coal creep and its stress,deformation and internal damage.The study could inform the deformation and internal damage evolution of coal during creep process.