To address the issue of wellbore instability and collapse in shale gas development,with Longmaxi shale as the research subject,based on uniaxial compression experiments and acoustic emission technology,the influences of bedding dip angles on shale failure,crack types,and the variation process of characteristic parameters of acoustic emission during the compression process were investigated.The results indicate that the main crack of the rock sample inclined at an angle of 30° traverses the bedding plane.The failure of the rock is predominantly governed by the rock matrix,and a certain bedding weak plane exists,resulting in the inclined macrocrack not fully propagating along the bedding plane.The coupling failure of rock samples with dip angles of 45° and 60° occurs.The rock failure is mainly controlled by the bedding plane,resulting in conspicuous slip failure.The failure plane along the bedding weak plane penetrates the entire rock sample.The rock sample with a dip angle of 90° is dominated by splitting failure.The crack propagation is influenced by the bedding plane,and the rock failure is governed by the weak bedding plane and the rock matrix.The count of acoustic emission ringing exhibits a fluctuating pattern and a disparity exists.Prior to the peak stress and when the rock sample is on the verge of being destroyed,the count of ringing increases rapidly to the maximum value.For the majority of the time,the acoustic emission energy is relatively low,and the acoustic emission energy rises as the crack propagates.When the rock sample fractures,the release of acoustic emission energy attains the maximum value.The positioning point display model processed by the clustering algorithm is superior to the Geiger algorithm positioning model in the expression of single concentrated rock macro-surface cracks and shedding areas.This study can provide a theoretical reference for wellbore stability analysis in shale gas development.
[1] 贾长贵,陈军海,郭印同,等.层状页岩力学特性及其破坏模式研究[J].岩土力学,2013,34(增刊2):57-61.
JIA Changgui,CHEN Junhai,GUO Yintong,et al.Research on mechanical behaviors and failure modes of layer shale [J].Rock and Soil Mechanics,2013,34(S2):57-61.
[2] 陈朝伟,王倩,赵亦朋,等.弱层理面地层的井壁稳定性分析[J].地下空间与工程学报,2016,12(增刊2):632-638.
CHEN Chaowei,WANG Qian,ZHAO Yipeng,et al.Wellbore stability analysis considering weak bedding plane[J].Chinese Journal of Underground Space and Engineering,2016,12(S2):632-638.
[3] 姚欢迎.基于声发射技术的页岩压缩损伤破坏实验研究[D].西安:西安石油大学,2020.
YAO Huanying.Experimental study on compression damage and failure of shale based on acoustic emission technology[D].Xi'an:Xi'an University of Petroleum,2020.
[4] 邹银辉.煤岩声发射机理初探[J].矿业安全与环保,2004,31(1):31-33,56.
ZOU Yinhui.Preliminary study on coal and rock acoustic emission mechanism and relevant experiments [J].Mining Safety & Environmental Protection,2004,31(1):31-33,56.
[5] 鲍如意.单轴受压条件下层状页岩的裂纹扩展规律及破坏机理研究[D].绍兴:绍兴文理学院,2021.
BAO Ruyi.Study on crack propagation law and failure mechanism of layer shale under uniaxial compression [D].Shaoxing:Shaoxing University,2021.
[6] 刘伟.层状岩体力学特性与破坏机理模型实验研究[D].武汉:武汉大学,2019.
LIU Wei.Experimental study on mechanical properties and failure mechanism model of layered rock mass[D].Wuhan:Wuhan University,2019.
[7] 陈雪萍,葛娟,陈忠清,等.单轴压缩条件下岩石声发射特征研究[J].土工基础,2021,35(4):507-509.
CHEN Xueping,GE Juan,CHEN Zhongqing,et al.Study on acoustic emission characteristics of rock under uniaxial compression[J].Geotechnical Foundation,2021,35(4):507-509.
[8] 谭赢,刘希灵,赵宇喆,等.基于巴西劈裂实验的岩石声发射特性及断口特征分析[J].实验力学,2021,36(2):241-249.
TAN Ying,LIU Xiling,ZHAO Yuzhe,et al.Failure analysis of pre-cracked specimen based on Brazilian splitting test[J].Experimental Mechanics,2021,36 (2):241-249.
[9] 王守光,刘耀儒,陈新,等.基于声发射技术的含裂纹石膏试件破坏分析[J].水力发电学报,2019,38(7):110-120.
WANG Shouguang,LIU Yaoru,CHEN Xin,et al.Failure analysis of cracked gypsum specimens based on acoustic emission technology[J].Journal of Hydroelectric Engineering,2019,38(7):110-120.
[10] 刘运思,王世鸣,颜世军,等.基于声发射实验层状砂岩力学特性及破坏机理[J].中南大学学报(自然科学版),2019,50(6):1419-1427.
LIU Yunsi,WANG Shiming,YAN Shijun,et al.Properties and failure mechanism of layered sandstone based on acoustic emission experiments[J].Journal of Central South University:Science and Technology,2019,50(6):1419-1427.
[11] 裴向军,朱凌,崔圣华,等.加卸载条件下含缺陷岩石声发射响应特征研究[J].岩石力学与工程学报,2020,39(增刊1):2602-2611.
PEI Xiangjun,ZHU Ling,CUI Shenghua,et al.Experimental study on acoustic emission characteristic of rocks with vein mass[J].Journal of Rock Mechanics and Engineering,2020,39(S1):2602-2611.
[12] DONG L,ZHANG Y,BI S,et al.Uncertainty investigation for the classification of rock micro-fracture types using acoustic emission parameters[J].International Journal of Rock Mechanics and Mining Sciences,2023,162:105292.
[13] 刘斌,赵毅鑫,张汉,等.单轴压缩及劈裂实验下煤的声发射特征研究[J].采矿与安全工程学报,2020,37(3):613-621.
LIU Bin,ZHAO Yixin,ZHANG Han,et al.Acoustic emission characteristics of coal under uniaxial compression and Brazilian splitting[J].Journal of Mining & Safety Engineering, 2020,37(3):613-621.
[14] 肖坤,张朝鹏,刘洋,等.适用于复杂实验条件下的声发射传感器布置装置设计[J].实验科学与技术,2021,19(1):140-144,154.
XIAO Kun,ZHANG Chaopeng,LIU Yang,et al.Design of acoustic emission sensor arrangement device for complex test condition[J].Experimental Science and Technology,2021,19(1):140-144,154.
[15] ZHANG Z H,DENG J H.A new method for determining the crack classification criterion in acoustic emission parameter analysis[J].International Journal of Rock Mechanics and Mining Sciences,2020,130:104323.
[16] 李俊平,余志雄,周创兵,等.水力耦合下岩石的声发射特征实验研究[J].岩石力学与工程学报,2006,25(3):492-498.
LI Junping,YU Zhixiong,ZHOU Chuangbing,et al.Experimental study on acoustic emission characteristics of rock under hydraulic coupling[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(3):492-498.
[17] 李俊平,汪晓霖,程慧高,等.声发射技术在武山铜矿的应用[J].岩石力学与工程学报,1996,15(增刊1):577-581.
LI Junping,WANG Xiaolin,CHENG Huigao,et al.Application of acoustic emission technique in Wushan copper mine[J].Chinese Journal of Rock Mechanics and Engineering,1996,15(S1):577-581.
[18] 舒龙勇,王凯,张浪,等.突出煤体受载变形破坏声发射行为演化特征[J].采矿与安全工程学报,2018,35(3):589-597.
SHU Longyong,WANG Kai,ZHANG Lang,et al.Investigation on acoustic emission behaviour evolution characteristics of outburst coal under uniaxial compression[J].Journal of Mining & Safety Engineering,2018,35(3):589-597.
