基于X-Ray CT试验的塌陷区回填体孔隙结构研究  

Application of X-Ray CT technology in the pore structure study of subsidence area backfilling body

作　　者：孙伟[1] 吴爱祥[2] 侯克鹏[1] 杨溢[1] 刘磊[1] 

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [2]北京科技大学土木与环境工程学院,北京100083

出　　处：《岩土力学》2017年第12期3635-3642,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.51574013;No.51374034;No.51504016);国家"十二五"科技支撑计划项目(No.2012BAB08B02)~~

摘　　要：为了研究地表塌陷区回填体破坏过程中的孔隙结构演化规律,利用医用X-Ray CT及小型加载装置开展了废石/尾砂混合回填体实时单轴压缩扫描试验,重构了不同应力状态下回填体的多组分结构模型。试验结果表明:随应力值增大,回填体孔隙率增加,应力超过峰值应力80%后,孔隙率陡增,孔隙主要以X型共轭面分布;回填体孔隙率随含石量增加而增大;回填体细观结构演化过程可划分孔洞持续压密、孔洞先压密后扩容、孔洞持续扩容、相邻微裂隙的贯通、不均质区的孔隙扩展6种模式;回填体在峰值应力80%以前,CT数、孔隙率变化幅度小,回填体中并未出现显著的贯穿性裂缝,主要以原生孔隙的压缩与扩容、次生孔隙的萌生与扩展两种状态为主;应力超过峰值应力80%后,CT数急剧降低,孔隙率陡增,回填体中的原生、次生孔隙结构逐渐贯通,形成贯穿性裂缝,回填体破坏。It is significant to investigate the evolution laws of pore structure during the process of backfill body damage in the surface subsidence zone. In this study, the medical X-Ray CT and small loading devices were employed to conduct real-time uniaxial compression scanning test on the backfill body with a mixture of waste rock and tailings. The multi-component structure models were reconstructed for the backfill body under different stress states. The results show that the backfilling porosity increased, as the stress value grew. When the stress value exceeded 80% of peak stress, the porosity increased sharply. Furthermore, pores were mainly distributed along the X-type conjugate surface. The backfilling porosity increased with the percentage of rock. The backfilling meso-structure evolution can be divided into six stages, including continuous compaction of pores, pore expansion after compaction,continuous expansion of pores, integration and expansion of pore groups, coalescence of adjacent micro-cracks, and pore expansion in heterogeneous areas. When the stress of the backfilling was less than 80% of the peak stress, both the CT number and porosity varied within small ranges. Although no significant penetrating cracks were observed in the backfilling, there were two main states, including the compression and expansion of the primary pores and the initiation and propagation of secondary pores. As the stress exceeded 80% of the peak stress, the CT number reduced drastically, while the porosity increased sharply. Meanwhile, the primary and secondary pore structures gradually connected in the backfilling and then formed penetrating cracks, resulting in the damage of the backfilling body.

关 键 词：地表塌陷区 回填体 X-RAY CT 三维重构 孔隙结构 

分 类 号：TD853[矿业工程—金属矿开采] TD88[矿业工程—矿山开采]