Abstract
Anchoring mechanism and failure characteristics of composite soft rock with weak interface usually exhibit remarkable difference from those in single rock mass. In order to fully understand the reinforcement mechanism of composite soft roof in western mining area of China, a mechanical model of composite soft rock with weak interface and rock bolt which considering the transverse shear sliding between different rock layers was established firstly. The anchoring effect was quantified by a factor defined as anchoring effect coefficient and its evolution equation was further deduced based on the deformation relationship and homogenized distribution assumption of stress acting on composite structure. Meanwhile, the numerical simulation model of composite soft rock with shear joint was prompted by finite element method. Then detailed analysis were carried out for the deformation features, stress distribution and failure behavior of rock mass and rock bolt near the joint under transverse load. The theoretical result indicates that the anchoring effect of rock-bolt through weak joint changes with the working status of rock mass and closely relates with the physical and geometric parameters of rock mass and rock bolt. From the numerical results, the bending deformation of rock bolt accurately characterized by Doseresp model is mainly concentrated between two plastic hinges near the shear joint. The maximum tensile and compression stresses distribute in the plastic hinge. However, the maximum shear stress appears at the positions of joint surface. The failure zones of composite rock are produced firstly at the joint surface due to the reaction of rock bolt. The above results laid a theoretical and computational foundation for further study of anchorage failure in composite soft rock.
摘要
复合软岩的锚固机理及锚固失效特征不同于单一岩体锚固。 针对西部矿区复合软岩顶板锚固问题, 考虑岩层间的横向剪切滑移, 建立了含软弱界面复合软岩锚固的力学模型; 提出采用锚固效应因子量化穿层锚杆的锚固效应; 从加锚复合岩体的变形破坏过程出发, 研究了系统锚杆的加固效果与机理, 建立加固效果演化方程; 采用有限元方法, 进一步建立了复合软岩锚固的数值计算模型, 分析了岩体在横向载荷作用下, 节理面附近锚杆和岩体的变形特征、 应力分布规律以及破坏行为。 理论研究结果表明, 穿层锚杆的加固效应与锚杆的刚度参数、 几何参数, 围岩的刚度参数和几何参数据有关。 锚固效应因子是一个随着围岩工作状态改变而变化的量。 从数值计算结果看, 锚杆在横向荷载作用下的弯折变形主要集中在节理面附近的两塑性铰之间, 变形曲线可用 Doseresp 模型进行表征; 在 2 个塑性铰处, 锚杆存在最大拉压应力, 在节理面处, 出现最大剪应力, 复合岩体在节理面附近由于锚杆的反作用最先出现塑性破坏区。 以上结果为进一步研究复合软岩锚固失效奠定了理论和计算基础。
Similar content being viewed by others
References
TAN Y L, LIU X S, NING J G, LU Y W. In situ investigations on failure evolution of overlying strata induced by mining multiple coal seams [J]. Geotechnical Testing Journal, 2017, 40(2): 1–14. DOI: https://doi.org/10.1520/GTJ20160090.
ZHAO Z H, WANG W M, WANG L H. Theoretical analysis of a new segmented anchoring style in weakly cemented soft surrounding rock [J]. International Journal of Mining Science and Technology, 2016, 26(3): 401–407. DOI: https://doi.org/10.1016/j.ijmst.2016.02.006.
ZHANG Le-wen, WANG Ren. Research on status quo of anchorage theory of rock and soil [J]. Rock and Soil Mechanics, 2002, 23(5): 627–631. (in Chinese)
PHILLIPS S. Factors affecting the design of anchorage sin rock [M]. London: Cementation Research Ltd., 1970.
MA S, NEMCIK J, AZIZ N. An analytical model of fully grouted rock bolts subjected to tensile load [J]. Construction and Building Materials, 2013, 49: 519–526. DOI: https://doi.org/10.1016/j.conbuildmat.2013.08.084.
REN F F, YANG Z J, CHEN J F, CHEN W W. An analytical analysis of the full-range behavior of grouted rockbolts based on a tri-linear bond-slip model [J]. Construction and Building Materials, 2010, 24(3): 361–370. DOI: https://doi.org/10.1016/j.conbuildmat.2009.08.021.
XIAO Shu-jun, CHEN Chang-fu. Mechanical mechanism analysis of tension type anchor based on shear displacement method [J]. Journal of Central South University of Technology, 2008(S1): 106–111. DOI: https://doi.org/10.1007/s11771-008-0021-z.
HE Si-ming, LI Xin-po. Study on mechanism of prestressed anchor bolt [J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25(9): 1876–1880. (in Chinese)
MUYA M S, HE B, WANG J T, LI G C. Effects of rock bolting on stress distribution around tunnel using the elastoplastic model [J]. Journal of Earth Science, 2006, 17(4): 337–341. DOI: https://doi.org/10.1016/S1002-0705(07)60008-9.
GOEL R K, ANIL S, SHEOREY P R. Bolt length requirement in underground openings [J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(5): 802–811. DOI: https://doi.org/10.1016/j.ijrmms.2006.12.001.
LIU H Y, SMALL J C, CARTER J P. Full 3D modelling for effects of tunnelling on existing support systems in the Sydney region [J]. Tunnelling and Underground Space Technology, 2007, 17(5): 569–572. DOI: https://doi.org/10.1016/j.tust.2007.06.009.
KILIC A, YASAR E, ATIS C D. Effect of bar shape on the pull out capacity of fully grouted rockbolts [J]. Tunneling and Underground Space Technology, 2003, 18(1): 1–6. DOI: https://doi.org/10.1016/S0886-7798(02)00077-9.
KILIC A, YASAR E, CELIK A G. Effect of grout properties on the pull out load capacity of fully grouted rock bolt [J]. Tunneling and Underground Space Technology, 2002, 17(4): 355–362. DOI: https://doi.org/10.1016/S0886-7798(02)00038-X.
BENMOKRANE B, CHENNOUF A, MITR H S. Laboratory evaluation of cement based grouts and grouted rock anchors [J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1995, 32(7): 633–642. DOI: https://doi.org/10.1016/0148-9062(95)00021-8.
BENMOKRANE B, XUE X H, BELLAVANCE E. Bond strength of cement grouted glass fibre reinforce plastic (GFRP) anchor bolts [J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1996, 33(5): 455–465. DOI: https://doi.org/10.1016/0148-9062(96)00006-X.
HOU Chao-jiong, GOU Pan-feng. Mechanism study on strength enhancement for the rocks surrounding roadway supported by rock [J]. Chinese Journal of Rock Mechanics and Engineering, 2000, 19(3): 342–345. (in Chinese)
YANG Shuang-suo, ZHANG Bai-sheng. The influence of bolt action force to the mechanical property of rocks [J]. Rock & Soil Mechanics, 2003, 24(S1): 279–282. (in Chinese)
SAWWAF M E, NAZIR A. The effect of soil reinforcement on pullout resistance of an existing vertical anchor plate in sand [J]. Computers and Geotechnics, 2006, 33(3): 167–176. DOI: https://doi.org/10.1016/j.compgeo.2006.04.001.
ZOU Zhi-hui, WANG Zhi-lin. Mechanism of anchor bar in different elastic modulus rocks by model test [J]. Chinese Journal of Geotechnical Engineering, 1993, 16(5): 71–78. (in Chinese)
LIU Ai-qing, JU Wen-jun, HU Hai-tao, WANG Xiang. Experimental study on the effect of bolt prestress on the shear behavior of jointed rockmass [J]. Journal of China Coal Society, 2013, 38(3): 391–396. (in Chinese)
LU Li, ZHANG Si-ping, ZHANG Yong-xing, LIN Wei-xun. Configuration optimization of pressure-dispersive anchors in soft-hard interbed of sedimentary rock [J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(S2): 4124–4130. (in Chinese)
YANG Jian-hui, XIA Jian-zhong. Test study on the complete deformation property of bolted stratified surrounding rockmasses [J]. Journal of China Coal Society, 2005, 30(4): 414–417. (in Chinese)
LI Xin-ping, WANG Tao, SONG Gui-hong, GUO Yun-hua, ZHANG Cheng-liang. Study on composite anchoring theory and numerical simulation test on layered rocks [J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25(S2): 3654–3660. (in Chinese)
CAO C, NEMCIK J, REN T, AZIZ N. A study of rock bolting failure modes [J]. International Journal of Mining Science and Technology, 2013, 23(1): 79–88. DOI: https://doi.org/10.1016/j.ijmst.2013.01.012.
SONG H W, DUAN Y Y, YANG J. Numerical simulation on bolted rock joint shearing performance [J]. International Journal of Mining Science and Technology, 2010, 20(3): 460–465. DOI: https://doi.org/10.1016/S1674-5264(09)60226-X.
GHABRAIE B, GHABRAIE K, XIE Y M. A study on truss bolt mechanism in controlling stability of underground excavation and cutter roof failure [J]. Geotechnical and Geological Engineering, 2013, 31(2): 667–682. DOI: https://doi.org/10.1007/s10706-013-9617-7.
JALALIFAR H, AZIZ N. Analytical behavior of bolt–joint intersection under lateral loading conditions [J]. Rock Mechanics and Rock Engineering, 2010, 43(1): 89–94. DOI: https://doi.org/10.1007/s00603-009-0032-6.
KAMAL C D, DEBASIS D, JHA A K. An enhanced numerical procedure for modelling fully grouted bolts intersected by rock joint [J]. Geosystem Engineering, 2013, 16(1): 37–46. DOI:https://doi.org/10.1080/12269328.2013.780738.
MARTIN L B, TIJANI M, HADJ-HASSEN F, NOIRET A. Assessment of the bolt-grout interface behavior of fully grouted rockbolts from laboratory experiments under axial loads [J]. International Journal of Rock Mechanics & Mining Sciences, 2013, 63: 50–61. DOI: https://doi.org/10.1016/j.ijrmms.2013.06.007.
JALALIFAR H, AZIZ N, HADI M N S. Non-linear analysis of bolt-grout-concrete interaction in reinforced shear joint [J]. Journal of Mines, Metals and Fuels, 2004, 52(9): 208–216. https://doi.org/www.researchgate.net/publication/289400703_Non-linear_analysis_of_bolt-grout-concrete_Interaction_in_reinforced_shear_joint.
JALALIFAR H, AZIZ N. Numerical simulation of fully grouted rock bolts [M]// Numerical Simulation-From Theory to Industry, Dr. Mykhaylo Andriychuk (Ed), InTech, 2012: 607–640. DOI: https://doi.org/10.5772/48287.
Author information
Authors and Affiliations
Corresponding author
Additional information
Foundation item: Projects(51774196, 41472280, 51578327) supported by the National Natural Science Foundation of China; Project(2016M592221) supported by the China Postdoctoral Science Foundation; Project(BJRC20160501) supported by the SDUST Young Teachers Teaching Talent Training Plan, China
Rights and permissions
About this article
Cite this article
Zhao, Zh., Gao, Xj., Tan, Yl. et al. Theoretical and numerical study on reinforcing effect of rock-bolt through composite soft rock-mass. J. Cent. South Univ. 25, 2512–2522 (2018). https://doi.org/10.1007/s11771-018-3932-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11771-018-3932-3