Failure mechanisms and destruction characteristics of cemented coal gangue backfill under compression effect of non-uniform load  

非均匀荷载压缩作用下矸石胶结充填体的破坏机理及特征

作　　者：FENG Guo-rui GUO Wei QI Ting-ye LI Zhu CUI Jia-qing WANG Hao-chen CUI Ye-kai MA Jing-kai 冯国瑞;郭伟;戚庭野;李竹;崔家庆;王昊晨;崔业凯;马敬凯(College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Shanxi Province Research Center of Green Mining Engineering Technology,Taiyuan 030024,China;Shanxi Province Coal-based Resources Green and High-efficiency Development Engineering Center,Taiyuan 030024,China;Shanxi Key Laboratory of Mine Rock Strata Control and Disaster Prevention,Taiyuan 030024,China;Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,Taiyuan 030024,China)

机构地区：[1]College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China [2]Shanxi Province Research Center of Green Mining Engineering Technology,Taiyuan 030024,China [3]Shanxi Province Coal-based Resources Green and High-efficiency Development Engineering Center,Taiyuan 030024,China [4]Shanxi Key Laboratory of Mine Rock Strata Control and Disaster Prevention,Taiyuan 030024,China [5]Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,Taiyuan 030024,China

出　　处：《Journal of Central South University》2024年第8期2676-2693,共18页中南大学学报（英文版）

基　　金：Project(51925402) supported by the National Natural Science Foundation for Distinguished Young Scholars of China;Project(202303021211060) supported by the Natural Science Research General Program for Shanxi Provincial Basic Research Program,China;Project(U22A20169) supported by the Joint Fund Project of National Natural Science Foundation of China;Projects(2021SX-TD001, 2021SX-TD002) supported by the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,China。

摘　　要：Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the stability of the backfill bodies is the primary prerequisite for maintaining the safety of the backfilling working face, and the loading characteristics of backfill are closely related to the deformation and subsidence of the roof. Elastic thin plate model was used to explore the non-uniform subsidence law of the roof, and then the non-uniform distribution characteristics of backfill bodies’ load were revealed. Through a self-developed non-uniform loading device combined with acoustic emission (AE) and digital image correlation (DIC) monitoring technology, the synergistic dynamic evolution law of the bearing capacity, apparent crack, and internal fracture of cemented coal gangue backfills (CCGBs) under loads with different degrees of non-uniformity was deeply explored. The results showed that: 1) The uniaxial compressive strength (UCS) of CCGB increased and then decreased with an increase in the degree of non-uniformity of load (DNL). About 40% of DNL was the inflection point of DNL-UCS curve and when DNL exceeded 40%, the strength decreased in a cliff-like manner;2) A positive correlation was observed between the AE ringing count and UCS during the loading process of the specimen, which was manifested by a higher AE ringing count of the high-strength specimen. 3) Shear cracks gradually increased and failure mode of specimens gradually changed from “X” type dominated by tension cracks to inverted “Y” type dominated by shear cracks with an increase in DNL, and the crack opening displacement at the peak stress decreased and then increased. The crack opening displacement at 40% of the DNL was the smallest. This was consistent with the judgment of crack size based on the AE b-value, i. e., it showed the typical characteristics of “small b-value-large crack and large b-value-small crack”. The r确保充填体的稳定是维护充填工作面安全的首要前提,而充填体受载特征与顶板的变形沉降密不可分。本文采用弹性薄板模型探究了顶板的非均匀下沉规律,进而揭示了充填体上覆荷载的非均匀分布特征。通过自主设计的非均匀加载装置模拟了充填体的非均匀受载过程。结果表明:随着荷载非均匀度的增加,矸石胶结充填体的单轴抗压强度先增大后减小。在试样加载过程中,声发射振铃计数与单轴抗压强度呈正相关,表现为高强度试样伴随更高的计数值。同时,荷载非均匀度的增加导致剪切裂纹逐渐增多,试样的破坏模式由拉伸裂纹为主的“X”型逐渐转变为剪切裂纹为主的倒“Y”型,并且导致峰值应力下的裂纹开度先减小后增大,这与根据声发射b值对裂纹大小的判断结果一致,即呈现出“小b值-大裂纹,大b值-小裂纹”的典型特征。实验得到的充填体上覆荷载非均匀度的临界值为40%,超过该值应对充填体进行补强,增加其宽度或进行柱旁支护。本研究成果旨在为预防充填体失稳破坏及指导充填方案设计提供参考和借鉴。

关 键 词：cemented coal gangue backfill non-uniform load degree of non-uniformity of load failure mode crack opening displacement 

分 类 号：TD823.7[矿业工程—煤矿开采]