节理岩体锚杆的综合变形分析
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摘要
在总结国内外对节理岩体中锚杆加固机制的试验研究和理论探讨基础上,综合考虑锚杆的切向和轴向变形能力,建立节理锚固锚杆在剪切荷载作用下的变形模型,将节理锚固锚杆的变形区划分为弹性变形段和挤压破坏段,引入表征挤压破坏段长度的变量,对锚杆与岩体的相互作用机制进行理论分析,推导了剪切荷载与剪切位移和轴向荷载与轴向位移的关系。通过分析锚杆的屈服破坏形式,得到了确定挤压破坏段长度的方法。最后,通过算例分析了挤压破坏段长度与锚杆直径、岩体强度、锚固角度等参数的关系,得到了以下结论:(1)节理锚固锚杆抗剪作用的实质是锚杆调动岩体的抗压强度抵抗节理切向荷载。在抗压强度较高的硬岩中,挤压破坏段局限于节理面附近,锚杆影响范围小;而在抗压强度较低的软岩中,挤压破坏段较大,而且会产生较大的剪切变形,锚杆影响范围较大。(2)锚杆屈服破坏形式与岩质和锚杆直径有关。硬质岩体发生剪切屈服,而较软岩体中容易发生弯曲屈服;小直径锚杆一般直接剪切屈服,而大直径锚杆可能发生弯曲屈服。锚杆屈服破坏后出现塑性铰,挤压破坏段范围在节理一侧约为直径的1～2倍,继续增加剪切荷载,挤压破坏段长度不再增大。(3)随岩质的不同,锚杆锚固节理的最优锚固角变化较大。岩质较硬时,最优锚固角度较小,反之则较大。
Based on the former experimental and theoretical researches on the reinforcement mechanisms of anchor bolt in jointed rock mass at home and abroad,and comprehensive considering of the tangential and axial deformability of anchor bolt,a deformation model of joint bolts under shear load is proposed.The deformation of joint bolts is divided into two parts: elastic deformation zone and crushing failure zone.A variable is introduced to express the length of crushing failure zone.Mechanism of interaction between bolts and rock mass is analyzed.Relationships between tangential load and tangential displacement,and axial load and axial displacement are deduced respectively.Through the analysis of yield failure model of bolt,a method to calculate the length of the crushing failure zone is proposed.Finally,a calculation example is presented to study the relationship between the length of crushing failure zone and the parameters,such as the bolt diameter,the rock mass strength,anchorage angle and so on.It is concluded that:(1) The shear resisting function of joint bolts is actually that the bolts arouse the compressive strength of rock mass to resist the shear load of the joint plane.In the hard rock with higher compressive strength,the crushing failure zone is limited near the joint plane and the influence area of bolt is small;while in soft rock with lower compressive strength,the length of crushing failure zone and shear deformation and the influence area of bolt is larger.(2) The yield failure mode of anchor bolt is related to rock properties and diameter of the bolt.Shear yield occurs in hard rock and bending yield occurs in soft rock.Bolt with little diameter usually go through shear yield and bolt with large diameter may go through bending yield.After yield failure,the plastic hinge appears.The length of the crushing failure zone on one side of the joint is 1-2 times of the bolt diameter,however,it no longer increases with the increasing of shear load.(3) The optimal anchor supporting angle of joint anchor bolt varies with rock properties.Hard rock has a smaller anchor supporting angle and the soft rock has a larger one.
Based on the former experimental and theoretical researches on the reinforcement mechanisms of anchor bolt in jointed rock mass at home and abroad,and comprehensive considering of the tangential and axial deformability of anchor bolt,a deformation model of joint bolts under shear load is proposed.The deformation of joint bolts is divided into two parts: elastic deformation zone and crushing failure zone.A variable is introduced to express the length of crushing failure zone.Mechanism of interaction between bolts and rock mass is analyzed.Relationships between tangential load and tangential displacement,and axial load and axial displacement are deduced respectively.Through the analysis of yield failure model of bolt,a method to calculate the length of the crushing failure zone is proposed.Finally,a calculation example is presented to study the relationship between the length of crushing failure zone and the parameters,such as the bolt diameter,the rock mass strength,anchorage angle and so on.It is concluded that:(1) The shear resisting function of joint bolts is actually that the bolts arouse the compressive strength of rock mass to resist the shear load of the joint plane.In the hard rock with higher compressive strength,the crushing failure zone is limited near the joint plane and the influence area of bolt is small;while in soft rock with lower compressive strength,the length of crushing failure zone and shear deformation and the influence area of bolt is larger.(2) The yield failure mode of anchor bolt is related to rock properties and diameter of the bolt.Shear yield occurs in hard rock and bending yield occurs in soft rock.Bolt with little diameter usually go through shear yield and bolt with large diameter may go through bending yield.After yield failure,the plastic hinge appears.The length of the crushing failure zone on one side of the joint is 1-2 times of the bolt diameter,however,it no longer increases with the increasing of shear load.(3) The optimal anchor supporting angle of joint anchor bolt varies with rock properties.Hard rock has a smaller anchor supporting angle and the soft rock has a larger one.
引文
[1]程良奎,张作嵋,杨志银.岩土加固技术[M].北京:地震出版社,1994.
[2]BJURSTR M S.Shear strength of hard rock jointsreinforced by grouted un-tensioned bolts[C]//Proceedingsof the 3rd International Congress on Rock Mechanics.Denver:[s.n.],1974,2(B):1194-1199.
[3]HAAS C J.Shear resistance of rock bolts[J].AIMETransactions,1976,260(1):32-41.
[4]DIGHT P M.Improvements to the stability of rock walls inopen pit mines[D].Melbourne:Monash University,1982.
[5]YOSHINAKA R,SKAGUCHI S,SHIMIZU T.Experimental study of the bolt reinforcement indiscontinuous rock[C]//Proceedings of 6th IRSMCongress.Montreal:International Society for RockMechanics,1987,1:1329-1332.
[6]SPANG K,EGGER P.Action of fully-grouted bolt injointed rock and factors of influence[J].Rock Mechanicsand Rock Engineering,1990,23(3):201-229.
[7]FERRERO A M.The shear strength of reinforced rockjoints[J].International Journal of Rock Mechanics andMining Sciences&Geomechanics Abstracts,1995,32(6):590-600.
[8]PELLET F,EGGER P.Analytic model for the mechanicalbehaviour of bolted rock joints subject to shearing[J].Rock Mechanics and Rock Engineering,1996,29(2):73-97.
[9]GRASSELLI G,KHARCHAfi M,EGGER P.Experimental and numerical comparison between fullygrouted and frictional bolts[C]//VOUILLE,BEREST.Proceedings of International Congress on RockMechanics.Paris:[s.n.],1999:903-907.
[10]葛修润,刘建武.加锚节理面抗剪性能研究[J].岩土工程学报,1988,10(1):8-19.GE Xiu-run,LIU Jian-wu.Study of the shear resistancebehaviour of bolted rock joints[J].Chinese Journal ofGeotechnical Engineering,1988,10(1):8-19.
[11]杨延毅,王慎跃.加锚节理岩体的损伤增韧止裂模型研究[J].岩土工程学报,1995,17(1):9-17.YANG Yan-yi,WANG Shen-yue.Study of toughening ofjointed rock masses reinforced with bolts[J].ChineseJournal of Geotechnical Engineering,1995,17(1):9-17.
[12]陈洪凯,唐红梅,王蓉,等.锚固岩体参数的等效方法研究[J].应用数学和力学,2001,22(8):862-868.CHEN Hong-kai TANG Hong-mei,WANG Rong,et al.Research on equivalent processes of rock massparameters with anchor piles[J].Applied Mathematicsand Mechanics,2001,22(8):862-868.
[13]杨松林,徐卫亚,朱焕春.锚杆在节理中的加固作用[J].岩土力学,2002,23(5):604-607.YANG Song-lin,XU Wei-ya,ZHU Huan-chun.Reinforcement of bolt in joints[J].Rock and SoilMechanics,2002,23(5):604-607.
[14]FULLER P G,COX R H T.Rock reinforcement designbased on control of joint displacement-a new concept[C]//Proceedings of 3rd Australian Tunnelling Conference.Sydney.Barton:Institution of Engineers,1978:28-35.
[15]FERRERO A M.The shear strength of reinforced rockjoints[J].International Joural of Rock Mechanics andMining Sciences and Geomechanics Abstracts,1995,32(6):595-605.
[16]ORESTE1 P P,CRAVERO M.An analysis of the actionof dowels on the stabilization of rock blocks onunderground excavation walls[J].Rock Mechanics andRock Engineering,2008,(41):835-868.
[17]朱训国.地下工程中注浆岩石锚杆锚固机理研究[D].大连:大连理工大学,2006.
[18]LI C,STILLBORG B.Analytical models for rock bolts[J].International Journal of Rock Mechanics and MiningSciences,1999,36(8);1013-1029.
[19]杨庆,朱训国,栾茂田.全长注浆岩石锚杆双曲线模型的建立及锚固效应的参数分析[J].岩石力学与工程学报,2007,26(4):692-698.YANG Qing,ZHU Xun-guo,LUAN Mao-tian.Development of hyperbolic model for fully grouting rockbolt and parameters analysis for anchoring effect[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(4):692-698.
[20]张季如,唐保付.锚杆荷载传递机理分析的双曲函数模型[J].岩土工程学报,2002,24(2):188-192.ZHANG Ji-ru,TANG Bao-fu.Hyperbolic function modelto analyze load transfer mechanism on bolts[J].ChineseJournal of Geotechnical Engineering,2002,24(2):188-192.
[2]BJURSTR M S.Shear strength of hard rock jointsreinforced by grouted un-tensioned bolts[C]//Proceedingsof the 3rd International Congress on Rock Mechanics.Denver:[s.n.],1974,2(B):1194-1199.
[3]HAAS C J.Shear resistance of rock bolts[J].AIMETransactions,1976,260(1):32-41.
[4]DIGHT P M.Improvements to the stability of rock walls inopen pit mines[D].Melbourne:Monash University,1982.
[5]YOSHINAKA R,SKAGUCHI S,SHIMIZU T.Experimental study of the bolt reinforcement indiscontinuous rock[C]//Proceedings of 6th IRSMCongress.Montreal:International Society for RockMechanics,1987,1:1329-1332.
[6]SPANG K,EGGER P.Action of fully-grouted bolt injointed rock and factors of influence[J].Rock Mechanicsand Rock Engineering,1990,23(3):201-229.
[7]FERRERO A M.The shear strength of reinforced rockjoints[J].International Journal of Rock Mechanics andMining Sciences&Geomechanics Abstracts,1995,32(6):590-600.
[8]PELLET F,EGGER P.Analytic model for the mechanicalbehaviour of bolted rock joints subject to shearing[J].Rock Mechanics and Rock Engineering,1996,29(2):73-97.
[9]GRASSELLI G,KHARCHAfi M,EGGER P.Experimental and numerical comparison between fullygrouted and frictional bolts[C]//VOUILLE,BEREST.Proceedings of International Congress on RockMechanics.Paris:[s.n.],1999:903-907.
[10]葛修润,刘建武.加锚节理面抗剪性能研究[J].岩土工程学报,1988,10(1):8-19.GE Xiu-run,LIU Jian-wu.Study of the shear resistancebehaviour of bolted rock joints[J].Chinese Journal ofGeotechnical Engineering,1988,10(1):8-19.
[11]杨延毅,王慎跃.加锚节理岩体的损伤增韧止裂模型研究[J].岩土工程学报,1995,17(1):9-17.YANG Yan-yi,WANG Shen-yue.Study of toughening ofjointed rock masses reinforced with bolts[J].ChineseJournal of Geotechnical Engineering,1995,17(1):9-17.
[12]陈洪凯,唐红梅,王蓉,等.锚固岩体参数的等效方法研究[J].应用数学和力学,2001,22(8):862-868.CHEN Hong-kai TANG Hong-mei,WANG Rong,et al.Research on equivalent processes of rock massparameters with anchor piles[J].Applied Mathematicsand Mechanics,2001,22(8):862-868.
[13]杨松林,徐卫亚,朱焕春.锚杆在节理中的加固作用[J].岩土力学,2002,23(5):604-607.YANG Song-lin,XU Wei-ya,ZHU Huan-chun.Reinforcement of bolt in joints[J].Rock and SoilMechanics,2002,23(5):604-607.
[14]FULLER P G,COX R H T.Rock reinforcement designbased on control of joint displacement-a new concept[C]//Proceedings of 3rd Australian Tunnelling Conference.Sydney.Barton:Institution of Engineers,1978:28-35.
[15]FERRERO A M.The shear strength of reinforced rockjoints[J].International Joural of Rock Mechanics andMining Sciences and Geomechanics Abstracts,1995,32(6):595-605.
[16]ORESTE1 P P,CRAVERO M.An analysis of the actionof dowels on the stabilization of rock blocks onunderground excavation walls[J].Rock Mechanics andRock Engineering,2008,(41):835-868.
[17]朱训国.地下工程中注浆岩石锚杆锚固机理研究[D].大连:大连理工大学,2006.
[18]LI C,STILLBORG B.Analytical models for rock bolts[J].International Journal of Rock Mechanics and MiningSciences,1999,36(8);1013-1029.
[19]杨庆,朱训国,栾茂田.全长注浆岩石锚杆双曲线模型的建立及锚固效应的参数分析[J].岩石力学与工程学报,2007,26(4):692-698.YANG Qing,ZHU Xun-guo,LUAN Mao-tian.Development of hyperbolic model for fully grouting rockbolt and parameters analysis for anchoring effect[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(4):692-698.
[20]张季如,唐保付.锚杆荷载传递机理分析的双曲函数模型[J].岩土工程学报,2002,24(2):188-192.ZHANG Ji-ru,TANG Bao-fu.Hyperbolic function modelto analyze load transfer mechanism on bolts[J].ChineseJournal of Geotechnical Engineering,2002,24(2):188-192.
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