Failure Characteristics and Engineering Application of Layered Rock with Two Pre-existing Non-coplanar Fissures
-
摘要: 为了研究层状岩石在预存裂隙作用下的破坏机理,基于颗粒离散元理论,构建能反映岩石各向异性特征的数值模型. 基于该模型,系统研究了含非共面双裂隙层状岩石在单轴压缩条件下裂纹的产生与演化规律,并揭示了双裂隙层状围岩中隧道开挖后岩体的破坏模式. 研究结果表明:存在预制裂隙的岩石,其抗压强度值小于相同条件下的完整岩石,但岩石强度与层理面倾斜角度的关系曲线仍呈U形分布;竖向加载时,试样的破坏形态同层理面倾斜角度(β)与预制裂隙倾斜角度(α)间相对大小有关. 当β < α时,岩石的破坏受预制裂隙控制;当β > α时,岩石的破坏可分为预制裂隙与层理面共同控制与层理面控制两类;隧道围岩的细观破坏模式也与β、α的相对大小有关,但破坏区域均集中在洞周两侧垂直于层理面的一定范围内.Abstract: In order to study the failure mechanism of layered rock with pre-existing cracks, a numerical model which is based on particle discrete element method and can reflect the anisotropic characteristics of rock is built. The initiation and propagation of micro-cracks in anisotropic rock with two pre-existing non-coplanar fissures under uniaxial compression tests are analyzed. Furthermore, the failure process of surrounding rock after tunnel excavation is also obtained. Results shows that, the compressive strength of specimens with pre-existing fissures is smaller than that of intact rock, while the curve of relationship between strength and inclination angles is still ‘U’ shaped. The failure patterns are controlled by inclination angle of bedding plane (β) and inclination angle of fissures (α). For β < α, failure is controlled by fissures; for β > α, failure is controlled by both fissures and bedding planes or bedding planes. Failure patterns of surrounding rock is also related to β and α, while the damage zone is concentrated in certain regions around the tunnel in the direction normal to layers in all cases.
-
Key words:
- layered rock mass /
- pre-existing fissures /
- discrete element method /
- failure pattern
-
表 1 PBM模型微观参数
Table 1. Micro-parameters of the parallel bond model
颗粒最小半径/
mm最大最小半径比 颗粒密度/
(kg•m3)颗粒间摩擦系数 颗粒弹性体模量/
GPa颗粒法向-切向刚度比 0.2 1.66 2 730 0.2 38 3.3 平行黏结系数 平行黏结弹性模
量/GPa平行黏结法向-切向刚度比 平行黏结法向强度/
MPa平行黏结切向强度/
MPa1 36 3.3 65 ± 15 120 ± 30 表 2 SJM模型微观参数
Table 2. Micro-parameters of the smooth joint model
法向刚度/
(GPa•m−1)切向刚度/
(GPa•m−1)摩擦系数 剪胀角/(°) 3700 860 0.4 0 黏结法向强度/MPa 黏结黏聚
力/MPa黏结摩
擦角/(°)3.5 20 14 表 3 试样破裂模式
Table 3. Fracture patterns
层理方
向/(°)裂隙参数(裂缝间距-搭接长度)/mm a-a a-0 a-a a-2a 2a-a 2a-0 2a-a 2a-2a 0 30 60 90 表 4 有限差分模型参数
Table 4. Parameters of the finite difference model
密度/
(kg•m3)平行于层面方向的弹性模量 E0/GPa 垂直于层面方向的弹性模 E90/GPa 平行于层面方向泊松比 ν0 垂直于层面方向泊松比 ν90 2 600 39.3 19.0 0.18 0.20 -
刘怀忠,谢红强,何江达,等. 石英云母片岩各向异性蠕变特性试验研究[J]. 西南交通大学学报,2015,50(4): 656-661. doi: 10.3969/j.issn.0258-2724.2015.04.013LIU Huaizhong, XIE Hongqiang, HE Jiangda, et al. Experimental investigation on anisotropic creep characteristics of quartz mica schist[J]. Journal of Southwest Jiaotong University, 2015, 50(4): 656-661. doi: 10.3969/j.issn.0258-2724.2015.04.013 AMADEI B. Importance of anisotropy when estimating and measuring insitu stresses in rock[J]. International Journal of Rock Mechanics and Mining Science & Geomechanical Abstract, 1996, 33(3): 293-325. BROWN E T, GREEN S J, SINHA K P. The influence of rock anisotropy on hole deviation in rotary drilling-a review[J]. International Journal of Rock Mechanics and Mining Science & Geomechanical Abstract, 1981, 18: 387-401. GONG Q M, ZHAO J, JIAO Y Y. Numerical modeling of the effects of joint orientation on rock fragmentation by TBM cutters[J]. Tunneling and Underground Space Technology, 2005, 20(2): 183-91. doi: 10.1016/j.tust.2004.08.006 徐国文,何川,汪 耀,等. 层状软岩隧道围岩破坏的连续-离散耦合分析[J]. 西南交通大学学报,2018,53(5): 966-973.XU Guowen, HE Chuan, WANG Yao. et al. Failure analysis on surrounding rock of soft-layered rock tunnel using coupled continuum-discrete model[J]. Journal of Southwest Jiaotong University, 2018, 53(5): 966-973. 代树红,王召,马胜利,等. 裂纹在层状岩石中扩展特征的研究[J]. 煤炭学报,2014,39(2): 315-321.DAI Shuhong, WANG Zhao, MA Shengli, et al. Study on characteristics of crack propagation in stratified rock[J]. Journal of China Coal Society, 2014, 39(2): 315-321. 陈天宇,冯夏庭,张希巍,等. 黑色页岩力学特性及各向异性特性试验研究[J]. 岩石力学与工程学报,2014,33(9): 1772-1779.CHEN Tianyu, FENG Xiating, ZHANG Xiwei, et al. Experimental study on mechanical and anisotropic properties of black shale[J]. Chinese Journal of Rock Mechanics and Engineering, 2014, 33(9): 1772-1779. 衡帅,杨春和,张保平,等. 页岩各向异性特征的试验研究[J]. 岩土力学,2015,36(3): 609-616.HENG Shuai, YANG Chunhe, ZHANG Baoping, et al. Experimental research on anisotropic properties of sh-ale[J]. Rock and Soil Mechanics, 2015, 36(3): 609-616. 刘胜利,陈善雄,余飞,等. 绿泥石片岩各向异性特性研究[J]. 岩土力学,2012,33(12): 3616-3623.LIU Shengli, CHEN Shanxiong, YU Fei, et al. Anisotropic properties study of chlorite schist[J]. Rock and Soil Mechanics, 2012, 33(12): 3616-3623. NASSERI M H B, RAO K S, RAMAMURTHY T. Anisotropic strength and deformational behavior of Himalayan schists[J]. International Journal of Rock Mechanics and Mining Sciences, 2003, 40(1): 3-23. doi: 10.1016/S1365-1609(02)00103-X 杨圣奇,黄彦华,温森. 高温后非共面双裂隙红砂岩力学特性试验研究[J]. 岩石力学与工程学报,2015,34(3): 440-451.YANG Shengqi, HUANG Yanhua, WEN Sen. Experimental study of mechanical behavior of red sandstone with two non-coplanar fissures after high temperature heating[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(3): 440-451. LEE H, JEON S. An experimental and numerical study of fracture coalescence in pre-cracked specimens under uniaxial compression[J]. International Journal of Solids and Structures, 2011, 48(6): 979-999. doi: 10.1016/j.ijsolstr.2010.12.001 WONG R H C, TANG C A, CHAU K T, et al. Splitting failure in brittle rocks containing pre-existing flaws under uniaxial compression[J]. Engineering Fracture Mechanics, 2002, 69(17): 1853-1871. doi: 10.1016/S0013-7944(02)00065-6 ZHANG X P, WONG L N Y. Crack initiation,propagation and coalescence in rock-like material containing two flaws:a numerical study based on bonded-particle model approach[J]. Rock Mechanics and Rock Engineering, 2013, 46(5): 1001-1021. doi: 10.1007/s00603-012-0323-1 蒋明镜,陈贺,张宁,等. 含双裂隙岩石裂纹演化机理的离散元数值分析[J]. 岩土力学,2014,35(11): 3259-3268.JIANG Mingjing, CHEN He, ZHANG Ning, et al. Distinct element numerical analysis of crack evolution in rocks containing pre-existing double flaw[J]. Rock and Soil Mechanics, 2014, 35(11): 3259-3268.