含弧形预制裂隙砂岩力学特征试验研究  

Mechanical characteristics of sandstone containing arc prefabricated fissures

作　　者：朱栋 靖洪文[1] 尹乾 陶祥令 宗义江[2] ZHU Dong;JING Hongwen;YIN Qian;TAO Xiangling;ZONG Yijiang(School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China;College of Energy and Transportation Engineering,Jiangsu Vocational Institute of Architectural Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学力学与土木工程学院,江苏徐州221116 [2]江苏建筑职业技术学院能源与交通工程学院,江苏徐州221116

出　　处：《煤炭学报》2019年第9期2721-2732,共12页Journal of China Coal Society

基　　金：国家自然科学基金重点资助项目(51734009);江苏省高校自然科学研究面上资助项目(16KJB580014);江苏省自然基金资助项目(BK20160208)

摘　　要：天然岩体中富含近似弧形裂隙缺陷,在外荷载作用下弧形裂隙容易萌生新生裂纹,新生裂纹的扩展容易导致岩石工程的失稳,但针对含弧形预制裂隙岩石力学相关特征的研究还不够全面,基于此在板状黄砂岩试样内预制了不同γ值(弧形高度和直径比值)的弧形裂隙,研究含弧形预制缺陷砂岩的力学特征。利用高压水射流切割机在完整板状黄砂岩试样中切割出不同γ值弧形裂隙缺陷,采用YNS-2000型电液伺服控制试验系统、DS2声发射和数字照相采集系统研究了不同弧形裂隙γ在单轴压缩作用下对黄砂岩峰值强度、平均模量、割线模量、声发射、破坏过程、起裂形式、起裂应力和破坏形式的影响规律。利用复变函数求解在弧形裂隙应力场中所构建的黎曼-希尔伯特问题,获得尖端应力强度因子表达式。试验结果表明:①弧形裂隙缺陷砂岩试样随着γ的增大,峰后试样的承载能力逐渐降低,试样峰值强度、平均模量和割线模量出现总体减小趋势,当γ=0.2时峰值强度最大为27.09MPa;当γ=1时峰值强度最小为18.99MPa。②预制弧形裂隙γ对试样起裂应力、起裂位置、破裂演化过程、声发射特征和破坏模式均具有重要影响,随着γ值的增大,试样起裂应力呈总体减小趋势,当γ=0.8时,试样的平均起裂应力最小,其值为4.99MPa;当γ=0时,试样的平均起裂应力值为11.08MPa,平均起裂应力值最大。③随着γ的增大,试样的破坏模式由拉剪混合破坏向拉伸破坏转变,当γ=0时,试样为拉剪破坏;当γ在0.2~1.0时,试样为拉伸破坏。初始起裂裂纹扩展并不是导致试样最终破坏的原因,次生裂纹的扩展与自由面贯通才是导致试样整体破坏原因,试样破坏瞬间释放大量弹性能导致岩块折断和表面剥落现象。通过对含弧形裂隙裂纹扩展机制探讨推导出应力强度因子表达式,并根据该表达式求出相应应力强度因子值,曲�The natural rock mass is rich in similar arc-shaped crack defects,and the arc-shaped crack is prone to generate new cracks under external load,and the growth of new cracks will easily lead to the instability of rock engineering structure.However,the mechanical characteristics of rock containing arc-shaped prefabricated frac-tures are not comprehensively understood.Based on this,the arc-shaped fractures with different γ values (arc-shaped height and diameter ratio) were prefabricated in the sheet yellow-sandstone sample to study the me-chanical characteristics of sandstone containing arc-shaped prefabricated fractures.Using high pressure water jet cutting machine to cut arc-shaped fractures with different γ values in complete sheet yellow-sandstone samples,the effects of different arc-shaped fractures γ under uniaxial compression on peak strength,mean modulus and secession modulus,acoustic emission,failure process,initiation mode,initiation stress and failure mode of yellow-sandstone were studied by the YNS-2000 electro-hydraulic servo control test system,DS2 acoustic emission and digital photographic acquisition system.The complex function was used to solve the Riemann-Hilbert problem in the curved fracture stress field.The experimental results show that:① The bearing capacity of the sample after peak decreases gradually and the peak strength,average modulus and secant modulus of the sample generally decrease with the increase of γ.The maximum peak intensity was 27.09 MPa when γ=0.2 and the peak intensity was at least 18.99 MPa when γ=1.② The inclination γ of arc crack has an important influence on the initiation stress,initiation position,fracture evolution,acoustic emission characteristics and failure modes.The crack initiation stress of the test specimen decreases in general with the increase of the antithesis value.The average crack initiation stress of the test specimen was at least 4.99 MPa when γ=0.8,and the average crack initiation stress of the sample was 11.08 MPa with the maximum average cr

关 键 词：弧形裂隙 起裂应力 破裂过程 声发射 应力强度因子 

分 类 号：TD313[矿业工程—矿井建设]