充填体破坏特征的聚类分析及数值模拟

Cluster analysis and numerical simulation of damage characteristic of cemented paste backfill

充填体破坏是影响矿山安全稳定的重要因素之一。为研究充填体的破坏特征,采用室内实验、机器学习层次聚类分析及数值模拟等方法,对矸石胶结充填体(GCPB)裂纹演化的全状态进行了研究。结果表明:当GCPB试样PC-5、PC-10、PC-15、PC-20的特征键平均键长能量分别大于35、50、60、150 ms·mV时,出现宏观主裂纹面,且主裂纹破坏面随水泥掺量的增加由张拉破坏面向剪切破坏面转变;破坏过程中特征键子集尺度Ω与损伤变量D之间呈负线性相关关系,Ω可表征充填体损伤演化程度;在应力达到峰值应力和破坏后残余强度前键长值特征空间相关长度ξ表现为明显增长,为充填体宏观损伤的开始及第1次破坏结束的前兆特征;通过颗粒流程序(PFC)数值模拟,可以有效观测到裂纹的类型和变化规律,数值模拟结果与聚类分析结果一致。

The damage of the cemented paste backfill is an important factor affecting the safety and stability of the mine.In order to explore the damage characteristics of the cemented paste backfill,the full state of gangue cemented paste backfill(GCPB)crack evolution was investigated by indoor experiments,machine learning hierarchical cluster analysis and numerical simulation.The results show that when the average link length energy of characteristic links of GCPB samples PC-5,PC-10,PC-15,PC-20 exceeded 35 ms·mV,50 ms·mV,60 ms·mV,150 ms·mV,the macroscopic main crack surface of developed,and the main crack damage surface changed from tensile to shear damage surface with the increase of Portland Cement(PC)dosing.During the damage process,there was a negative linear relationship between the characteristic link subset scaleΩand the damage variable D.The value ofΩcould characterize the degree of damage evolution of the cemented paste backfill.Before the stress reaches the peak stress and post-damage residual strength,the link length value eigenspace correlation lengthξshowed a significant increase.This could be the precursor feature of the beginning of macroscopic damage and the end of the first damage of the cemented paste backfill.Through PFC numerical simulation,the crack type and variation pattern can be observed effectively,which is in good agreement with the clustering results.