含孔洞层状砂岩动态压缩力学特性试验研究
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摘要
隧道、矿山巷道和硐室等地下岩石工程中揭露的层状岩体往往具有不同的产状,层理弱面的方向与主要动荷载作用方向存在多种组合,相应的动态各向异性力学特性和变形破坏特征对地下岩石工程安全稳定具有至关重要的影响。针对冲击载荷下倾斜层状岩体中巷道围岩稳定性问题,选取一种层理构造显著的黄砂岩,其中层理倾角φ为层理面与加载方向之间的夹角,加工制备倾角分别为0°,15°,30°,45°,60°,75°和90°的7组预制中央圆形孔洞板状试样(尺寸为宽度60 mm×高度60 mm×厚度15 mm),在75 mm杆径分离式霍普金森压杆(SHPB)试验平台上进行冲击压缩试验,并使用高速摄影仪实时记录试样动态裂纹扩展演化过程,研究不同层理倾角条件下预制中心孔洞层状岩石的动态力学参数、裂纹扩展演化过程及最终破坏模式等动态压缩力学特性变化规律。结果表明,峰值应力处试样破坏的峰值应变在0. 008 1～0. 012 37变化,随着层理倾角的增加,试样动态抗压强度、弹性模量及峰值应变整体均呈先增大后减小的变化规律;初始起裂裂纹总是从孔洞周边压应力集中处萌生,随后逐渐形成宏观裂纹,宏观裂纹为剪切裂纹或拉剪复合裂纹;倾角0°试样发生局部沿层理和局部穿越层理的复合张剪破坏,倾角15°～45°试样发生局部沿层理和局部穿越层理的剪切破坏,倾角60°～90°试样最终发生穿越层理的类X型剪切破坏;利用正交各向异性板理论计算孔洞周边应力分布,发现随着层理倾角的增加,孔洞周边应力集中系数的峰值也逐渐增大,且层理倾角为0°,15°,30°,45°的试样孔洞周边最大压应力出现在θ(θ为孔洞周边任意一点的极角)为74°,81°,86°,90°及关于原点中心对称的254°,261°,266°,270°处,同时试验中观测到相应的层理倾角试样分别在88°,85°,79°,70°及关于原点对称的271°,264°,262°,252°处萌生剪切裂纹,与理论分析结果吻合较好。层理方向与冲击载荷平行时,层状岩体中巷道围岩对冲击载荷的承载能力最弱。针对钻爆法分台阶开挖硐室或爆破施工中存在近距既有巷道,应合理布置爆破载荷的方向,避免层理方向与爆破载荷之间的夹角过小而导致巷道失稳。
The exposed layered rock masses with different attitudes can be found in many underground openings such as tunnel,mine roadway and chamber. With various combinations of orientation of layers and loading direction,the dynamic anisotropic mechanical and deformation properties of rock masses affect crucially the engineering stability and safety. The paper aimed to research the surrounding rock stability of roadway in inclined stratified rock mass. To investigate the variation of the dynamic mechanical parameters,fracture propagation and failure modes of flawed bedding sandstone under different layer dip angles,the plate-shape bedding sandstone specimens were manufactured with a single circular hole in the specimen center. A series of dynamic impact tests were carried out using a?75 mm split Hopkinson pressure bar(SHPB) system on seven groups of bedding sand-stone specimens(size of 60 mm×60 mm×15 mm) which contain different layer dip anglesφ(including 0°,15°,30°,45°,60°,75° and 90°),where the dip angleφis the angle between the orientation of layers and the loading direction. The dynamic fracture evolution processes of specimens were recorded with a high-speed camera. The experimental results indicate that the strain corresponding to stress peak value ranges from 0. 008 1 to 0. 012 37. With the increase of dip angle,the dynamic compressive strength,the strain corresponding to the stress peak value and elastic modulus of specimens increase firstly and then decrease in general. Shear cracks or tensile-shear mixed cracks always initiate from the compressive stress concentration areas around the holes,and then develop to macroscopic fractures. The low-dip specimens(φ=0°) exhibit combined tensile-shear failure across and along the bedding plane. The medium-dip specimens(φ=15°,30° and 45°) exhibit shear failure across and along the bedding plane. The highly dipping specimens(φ=60°,75° and 90°) exhibit X-type shear failure. Orthogonal anisotropic plate theory was applied to calculate the stress distribution around the holes. The peak stress concentration factors around the holes increase with the increase of layer dip anglesφ. The maximal compressive stresses of low and medium-dip specimens around the holes appear at the position ofθ=90°,86°,81° and 74°(central symmetric position about the origin ofθ=270°,266°,261° and 254°),respectively,whereθis the polar angle of any point around the holes. The observed crack initiation locations of low and medium-dip specimens around the holes appear at the position ofθ=88°,85°,79° and 70°(central symmetric position about the origin ofθ=271°,264°,262° and 252°),respectively,which are roughly consistent to the position of maximal compressive stresses in theoretical analysis. Under impact loading,the load-bearing capacity of roadway surrounding rock in laminated rock is at its weakest,while the orientation of layers parallel to the loading direction. For the excavation of underground chamber with the combination of drilling-and blasting-method and bench cut method,or excavation blasting construction with near-existing roadway,the load-bearing capacity of roadway surrounding rock in laminated rock will be improved if the direction of explosive loading can be arranged reasonably.
The exposed layered rock masses with different attitudes can be found in many underground openings such as tunnel,mine roadway and chamber. With various combinations of orientation of layers and loading direction,the dynamic anisotropic mechanical and deformation properties of rock masses affect crucially the engineering stability and safety. The paper aimed to research the surrounding rock stability of roadway in inclined stratified rock mass. To investigate the variation of the dynamic mechanical parameters,fracture propagation and failure modes of flawed bedding sandstone under different layer dip angles,the plate-shape bedding sandstone specimens were manufactured with a single circular hole in the specimen center. A series of dynamic impact tests were carried out using a?75 mm split Hopkinson pressure bar(SHPB) system on seven groups of bedding sand-stone specimens(size of 60 mm×60 mm×15 mm) which contain different layer dip anglesφ(including 0°,15°,30°,45°,60°,75° and 90°),where the dip angleφis the angle between the orientation of layers and the loading direction. The dynamic fracture evolution processes of specimens were recorded with a high-speed camera. The experimental results indicate that the strain corresponding to stress peak value ranges from 0. 008 1 to 0. 012 37. With the increase of dip angle,the dynamic compressive strength,the strain corresponding to the stress peak value and elastic modulus of specimens increase firstly and then decrease in general. Shear cracks or tensile-shear mixed cracks always initiate from the compressive stress concentration areas around the holes,and then develop to macroscopic fractures. The low-dip specimens(φ=0°) exhibit combined tensile-shear failure across and along the bedding plane. The medium-dip specimens(φ=15°,30° and 45°) exhibit shear failure across and along the bedding plane. The highly dipping specimens(φ=60°,75° and 90°) exhibit X-type shear failure. Orthogonal anisotropic plate theory was applied to calculate the stress distribution around the holes. The peak stress concentration factors around the holes increase with the increase of layer dip anglesφ. The maximal compressive stresses of low and medium-dip specimens around the holes appear at the position ofθ=90°,86°,81° and 74°(central symmetric position about the origin ofθ=270°,266°,261° and 254°),respectively,whereθis the polar angle of any point around the holes. The observed crack initiation locations of low and medium-dip specimens around the holes appear at the position ofθ=88°,85°,79° and 70°(central symmetric position about the origin ofθ=271°,264°,262° and 252°),respectively,which are roughly consistent to the position of maximal compressive stresses in theoretical analysis. Under impact loading,the load-bearing capacity of roadway surrounding rock in laminated rock is at its weakest,while the orientation of layers parallel to the loading direction. For the excavation of underground chamber with the combination of drilling-and blasting-method and bench cut method,or excavation blasting construction with near-existing roadway,the load-bearing capacity of roadway surrounding rock in laminated rock will be improved if the direction of explosive loading can be arranged reasonably.
引文
[1]甄秉国.兰渝线桃树坪隧道区域上第三系砂岩工程特性分析[J].铁道建筑,2013,(5):55-57.ZHEN Bingguo.Study the N-Sandstone engineering character in Taoshuping Tunnel of Lanzhou to Chongqing Railway[J].Railway Engineering,2013,(5):55-57.
[2]LI Diyuan,WONG Louis Ngai Yuen,LIU Gang,et al.Influence of water content and anisotropy on the strength and deformability of low porosity meta-sedimentary rocks under triaxial compression[J].Engineering Geology,2012,126:46-66.
[3]TIEN Yong Ming,KUO Ming Chuan,CHARNG Hsein Juang.An experimental investigation of the failure mechanism of simulated transversely isotropic rocks[J].International Journal of Rock Mechanics and Mining Sciences,2006,43(8):1163-1181.
[4]QIU Jiadong,LI Diyuan,LI Xibing,et al.Dynamic fracturing behavior of layered rock with different inclination angles in SHPB tests[J].Shock and Vibration,2017,2017:12.
[5]SAEIDI Omid,RASOULI Vamegh,VANEGHI Rashid Geranmayeh,et al.A modified failure criterion for transversely isotropic rocks[J].Geoscience Frontiers,2014,5(2):215-225.
[6]ZHAO Yixin,ZHAO Gaofeng,JIANG Yaodong,et al.Effects of bedding on the dynamic indirect tensile strength of coal:Laboratory experiments and numerical simulation[J].International Journal of Coal Geology,2014,132:81-93.
[7]李地元,邱加冬,李夕兵.冲击载荷作用下层状砂岩动态拉压力学特性研究[J].岩石力学与工程学报,2015,34(10):2091-2097.LI Diyuan,QIU Jiadong,LI Xibing.Experimental study on dynamic tensile and compressive properties of bedding sandstone under impact loading[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(10):2091-2097.
[8]TAVALLALI A,VERVOORT A.Failure of layered sandstone under Brazilian test conditions:Effect of micro-scale parameters on macroscale behaviour[J].Rock Mechanics and Rock Engineering,2010,43(5):641-653.
[9]TAVALLALI A,VERVOORT A.Behaviour of layered sandstone under Brazilian test conditions:Layer orientation and shape effects[J].Journal of Rock Mechanics and Geotechnical Engineering,2013,5(5):366-377.
[10]BOBET A,EINSTEIN H H.Numerical modeling of fracture coalescence in a model rock material[J].International Journal of Fracture,1998,92(3):221-52.
[11]FUJII Y,ISHIJIMA Y.Consideration of fracture growth from an inclined slit and inclined initial fracture at the surface of rock and mortar in compression[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(6):1035-1041.
[12]HAN Zhenyu,LI Diyuan,ZHU Quanqi,et al.Dynamic fracture evolution and mechanical behavior of sandstone containing noncoplanar elliptical flaws under impact loading[J].Advances in Civil Engineering,2018,2018:16.
[13]LI Diyuan,HAN Zhenyu,SUN Xiaolei,et al.Dynamic mechanical properties and fracturing behavior of marble specimens containing single and double flaws in SHPB tests[J].Rock Mechanics and Rock Engineering,2018:doi:https://doi.org/10.1007/s00603-018-1652-5.
[14]LI Diyuan,ZHU Quanqi,ZHOU Zilong,et al.Fracture analysis of marble specimens with a hole under uniaxial compression by digital image correlation[J].Engineering Fracture Mechanics,2017,183:109-124.
[15]黄彦华,杨圣奇.含两组交叉节理砂岩强度及破坏特征离散元分析[J].煤炭学报,2015,40(S1):76-84.HUANG Yanhua,YANG Shengqi.Discrete element study on strength and failure behavior of jointed sandstone with two sets of cross-joints[J].Journal of China Coal Society,2015,40(S1):76-84.
[16]李地元,成腾蛟,周韬,等.冲击载荷作用下含孔洞大理岩动态力学破坏特性试验研究[J].岩石力学与工程学报,2015,34(2):249-260.LI Diyuan,CHENG Tengjiao,ZHOU Tao,et al.Experimental study of the dynamic strength and fracturing characteristics of marble specimens with a single hole under impact loading[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(2):249-260.
[17]苏海健,靖洪文,赵洪辉,等.纵向裂隙对砂岩力学特性影响试验研究[J].采矿与安全工程学报,2014,31(4):644-649.SU Haijian,JING Hongwen,ZHAO Honghui,et al.Experimental study on the influence of longitudinal fissure on mechanics characteristic of sandstone[J].Journal of Mining and Safety Engineering,2014,31(4):644-649.
[18]谢和平,陈忠辉,王家臣.放顶煤开采巷道裂隙的分形研究[J].煤炭学报,1998,23(3):30-35.XIE Heping,CHEN Zhonghui,WANG Jiachen.Fractal study on crack distribution in tunnels for sub-level caving mining[J].Journal of China Coal Society,1998,23(3):30-35.
[19]杨圣奇,戴永浩,韩立军,等.断续预制裂隙脆性大理岩变形破坏特性单轴压缩试验研究[J].岩石力学与工程学报,2009,28(12):2391-2404.YANG Shengqi,DAI Yonghao,HAN Lijun,et al.Uniaxial compression experimental research on deformation and failure properties of brittle marble specimen with pre-existing fissures[J].Chinese Journal of Rock Mechanics&Engineering,2009,28(12):2391-2404.
[20]杨圣奇,温森,李良权.不同围压下断续预制裂纹粗晶大理岩变形和强度特性的试验研究[J].岩石力学与工程学报,2007,26(8):1572-1587.YANG Shengqi,WEN Sen,LI Liangquan.Experimental study on deformation and strength properties of coarse marble with discontinuous pre-existing cracks under different confining pressures[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(8):1572-1587.
[21]李地元,韩震宇,孙小磊,等.含预制裂隙大理岩SHPB动态力学破坏特性试验研究[J].岩石力学与工程学报,2017,36(12):2872-2883.LI Diyuan,HAN Zhenyu,SUN Xiaolei,et al.Characteristics of dynamic failure of marble with artificial flaws under split Hopkinson pressure bar tests[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(12):2872-2883.
[22]LI Wenping,WANG Qiqing,LIU Shiliang,et al.Study on the creep permeability of mining-cracked N2laterite as the key aquifuge for preserving water resources in Northwestern China[J].International Journal of Coal Science&Technology,2018,5(3):315-327.
[23]LIU P,JU Y,RANJITH P G,et al.Visual representation and characterization of three-dimensional hydrofracturing cracks within heterogeneous rock through 3D printing and transparent models[J].International Journal of Coal Science&Technology,2016,3(3):284-294.
[24]JIA Lichun,CHEN Mian,JIN Yan,et al.Numerical simulation of failure mechanism of horizontal borehole in transversely isotropic shale gas reservoirs[J].Journal of Natural Gas Science and Engineering,2017,45:65-74.
[25]WANG S Y,SLOAN S W,SHENG D C,et al.Numerical analysis of the failure process around a circular opening in rock[J].Computers and Geotechnics,2012,39:8-16.
[26]WANG S Y,SLOAN S W,TANG C A,et al.Numerical simulation of the failure mechanism of circular tunnels in transversely isotropic rock masses[J].Tunnelling and Underground Space Technology,2012,32:231-244.
[27]张优利,刘胜春,杨克文,等.隧道爆破对小近距既有病害隧道的影响及控制[J].交通科技,2013,(3):102-105.ZHANG Youli,LIU Shengchun,YANG Kewen,et al.Influence of blasting construction on closely-spaced disease tunnel and its control[J].Transportation Science&Technology,2013,(3):102-105.
[28]YU Haitao,CHEN Juntao,YUAN Yong,et al.Seismic damage of mountain tunnels during the 5.12 Wenchuan earthquake[J].Journal of Mountain Science,2016,13(11):1958-1974.
[29]李夕兵.岩石动力学基础与应用[M].北京:科学出版社,2014.
[30]ZHOU Y X,XIA K,LI X B,et al.Suggested methods for determining the dynamic strength parameters and mode-I fracture toughness of rock materials[J].International Journal of Rock Mechanics and Mining Sciences,2012,49:105-112.
[31]列赫尼茨基C·Г.各向异性板[M].胡海昌译,北京:科学出版社,1963.
[2]LI Diyuan,WONG Louis Ngai Yuen,LIU Gang,et al.Influence of water content and anisotropy on the strength and deformability of low porosity meta-sedimentary rocks under triaxial compression[J].Engineering Geology,2012,126:46-66.
[3]TIEN Yong Ming,KUO Ming Chuan,CHARNG Hsein Juang.An experimental investigation of the failure mechanism of simulated transversely isotropic rocks[J].International Journal of Rock Mechanics and Mining Sciences,2006,43(8):1163-1181.
[4]QIU Jiadong,LI Diyuan,LI Xibing,et al.Dynamic fracturing behavior of layered rock with different inclination angles in SHPB tests[J].Shock and Vibration,2017,2017:12.
[5]SAEIDI Omid,RASOULI Vamegh,VANEGHI Rashid Geranmayeh,et al.A modified failure criterion for transversely isotropic rocks[J].Geoscience Frontiers,2014,5(2):215-225.
[6]ZHAO Yixin,ZHAO Gaofeng,JIANG Yaodong,et al.Effects of bedding on the dynamic indirect tensile strength of coal:Laboratory experiments and numerical simulation[J].International Journal of Coal Geology,2014,132:81-93.
[7]李地元,邱加冬,李夕兵.冲击载荷作用下层状砂岩动态拉压力学特性研究[J].岩石力学与工程学报,2015,34(10):2091-2097.LI Diyuan,QIU Jiadong,LI Xibing.Experimental study on dynamic tensile and compressive properties of bedding sandstone under impact loading[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(10):2091-2097.
[8]TAVALLALI A,VERVOORT A.Failure of layered sandstone under Brazilian test conditions:Effect of micro-scale parameters on macroscale behaviour[J].Rock Mechanics and Rock Engineering,2010,43(5):641-653.
[9]TAVALLALI A,VERVOORT A.Behaviour of layered sandstone under Brazilian test conditions:Layer orientation and shape effects[J].Journal of Rock Mechanics and Geotechnical Engineering,2013,5(5):366-377.
[10]BOBET A,EINSTEIN H H.Numerical modeling of fracture coalescence in a model rock material[J].International Journal of Fracture,1998,92(3):221-52.
[11]FUJII Y,ISHIJIMA Y.Consideration of fracture growth from an inclined slit and inclined initial fracture at the surface of rock and mortar in compression[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(6):1035-1041.
[12]HAN Zhenyu,LI Diyuan,ZHU Quanqi,et al.Dynamic fracture evolution and mechanical behavior of sandstone containing noncoplanar elliptical flaws under impact loading[J].Advances in Civil Engineering,2018,2018:16.
[13]LI Diyuan,HAN Zhenyu,SUN Xiaolei,et al.Dynamic mechanical properties and fracturing behavior of marble specimens containing single and double flaws in SHPB tests[J].Rock Mechanics and Rock Engineering,2018:doi:https://doi.org/10.1007/s00603-018-1652-5.
[14]LI Diyuan,ZHU Quanqi,ZHOU Zilong,et al.Fracture analysis of marble specimens with a hole under uniaxial compression by digital image correlation[J].Engineering Fracture Mechanics,2017,183:109-124.
[15]黄彦华,杨圣奇.含两组交叉节理砂岩强度及破坏特征离散元分析[J].煤炭学报,2015,40(S1):76-84.HUANG Yanhua,YANG Shengqi.Discrete element study on strength and failure behavior of jointed sandstone with two sets of cross-joints[J].Journal of China Coal Society,2015,40(S1):76-84.
[16]李地元,成腾蛟,周韬,等.冲击载荷作用下含孔洞大理岩动态力学破坏特性试验研究[J].岩石力学与工程学报,2015,34(2):249-260.LI Diyuan,CHENG Tengjiao,ZHOU Tao,et al.Experimental study of the dynamic strength and fracturing characteristics of marble specimens with a single hole under impact loading[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(2):249-260.
[17]苏海健,靖洪文,赵洪辉,等.纵向裂隙对砂岩力学特性影响试验研究[J].采矿与安全工程学报,2014,31(4):644-649.SU Haijian,JING Hongwen,ZHAO Honghui,et al.Experimental study on the influence of longitudinal fissure on mechanics characteristic of sandstone[J].Journal of Mining and Safety Engineering,2014,31(4):644-649.
[18]谢和平,陈忠辉,王家臣.放顶煤开采巷道裂隙的分形研究[J].煤炭学报,1998,23(3):30-35.XIE Heping,CHEN Zhonghui,WANG Jiachen.Fractal study on crack distribution in tunnels for sub-level caving mining[J].Journal of China Coal Society,1998,23(3):30-35.
[19]杨圣奇,戴永浩,韩立军,等.断续预制裂隙脆性大理岩变形破坏特性单轴压缩试验研究[J].岩石力学与工程学报,2009,28(12):2391-2404.YANG Shengqi,DAI Yonghao,HAN Lijun,et al.Uniaxial compression experimental research on deformation and failure properties of brittle marble specimen with pre-existing fissures[J].Chinese Journal of Rock Mechanics&Engineering,2009,28(12):2391-2404.
[20]杨圣奇,温森,李良权.不同围压下断续预制裂纹粗晶大理岩变形和强度特性的试验研究[J].岩石力学与工程学报,2007,26(8):1572-1587.YANG Shengqi,WEN Sen,LI Liangquan.Experimental study on deformation and strength properties of coarse marble with discontinuous pre-existing cracks under different confining pressures[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(8):1572-1587.
[21]李地元,韩震宇,孙小磊,等.含预制裂隙大理岩SHPB动态力学破坏特性试验研究[J].岩石力学与工程学报,2017,36(12):2872-2883.LI Diyuan,HAN Zhenyu,SUN Xiaolei,et al.Characteristics of dynamic failure of marble with artificial flaws under split Hopkinson pressure bar tests[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(12):2872-2883.
[22]LI Wenping,WANG Qiqing,LIU Shiliang,et al.Study on the creep permeability of mining-cracked N2laterite as the key aquifuge for preserving water resources in Northwestern China[J].International Journal of Coal Science&Technology,2018,5(3):315-327.
[23]LIU P,JU Y,RANJITH P G,et al.Visual representation and characterization of three-dimensional hydrofracturing cracks within heterogeneous rock through 3D printing and transparent models[J].International Journal of Coal Science&Technology,2016,3(3):284-294.
[24]JIA Lichun,CHEN Mian,JIN Yan,et al.Numerical simulation of failure mechanism of horizontal borehole in transversely isotropic shale gas reservoirs[J].Journal of Natural Gas Science and Engineering,2017,45:65-74.
[25]WANG S Y,SLOAN S W,SHENG D C,et al.Numerical analysis of the failure process around a circular opening in rock[J].Computers and Geotechnics,2012,39:8-16.
[26]WANG S Y,SLOAN S W,TANG C A,et al.Numerical simulation of the failure mechanism of circular tunnels in transversely isotropic rock masses[J].Tunnelling and Underground Space Technology,2012,32:231-244.
[27]张优利,刘胜春,杨克文,等.隧道爆破对小近距既有病害隧道的影响及控制[J].交通科技,2013,(3):102-105.ZHANG Youli,LIU Shengchun,YANG Kewen,et al.Influence of blasting construction on closely-spaced disease tunnel and its control[J].Transportation Science&Technology,2013,(3):102-105.
[28]YU Haitao,CHEN Juntao,YUAN Yong,et al.Seismic damage of mountain tunnels during the 5.12 Wenchuan earthquake[J].Journal of Mountain Science,2016,13(11):1958-1974.
[29]李夕兵.岩石动力学基础与应用[M].北京:科学出版社,2014.
[30]ZHOU Y X,XIA K,LI X B,et al.Suggested methods for determining the dynamic strength parameters and mode-I fracture toughness of rock materials[J].International Journal of Rock Mechanics and Mining Sciences,2012,49:105-112.
[31]列赫尼茨基C·Г.各向异性板[M].胡海昌译,北京:科学出版社,1963.