附加载荷作用下空区顶板稳定性分析
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摘要
以齐大山铁矿为工程背景,利用FLAC3D软件和Mohr-Coulomb屈服准则,通过极限分析方法和数值模拟技术相结合,研究了在附加载荷的作用下,不同厚度的空区顶板的稳定性.计算结果表明:当顶板厚度小于5.5 m时,顶板的破坏以受拉伸破坏为主,破坏区呈"拱"形向围岩内发展,此时的安全系数和极限承载能力随顶板厚度的变化并不明显,近似呈线性关系;当厚度大于5.5 m后,顶板的安全系数和极限承载能力随顶板厚度增大而迅速增加,因而建议对于10 m跨度的空区,其顶板安全应不小于5.5 m.对岩体黏聚力、内摩擦角和抗拉强度同步进行折减得到破坏区与增量加载的计算结果相似,得到的安全系数要小于仅折减黏聚力和内摩擦角得出的结果,因而,对不同顶板厚度安全系数的计算,需要考虑拉伸破坏的影响.
In order to study the gob area roof stability of Qidashan iron mine,the numerical software FLAC3D and limit analysis method were used to simulate the deformation and failure situation of the roof with different thickness under additional loading.In the simulation,the Mohr-Coulomb criterion was adopted,which can consider both the tensile and the shear failure of materials.The results show that when the roof thickness is less than 5.5 m,the tensile failure is the main mode.It will lead to the great increase of arch plastic zone areas.The strength reduction safety factor and the ultimate bearing capacity with the increasing roof thickness are not significant and have an approximately linear relationship.When the roof thickness is more than 5.5 m,the safety factor and ultimate bearing capacity are increased remarkably.The roof thickness is thus determined to be more than 5.5 m for the gob spacing of 10 m,which can ensure the roof stability under roof rock weight and additional loading.With the reduction of material parameters of cohesion c,internal friction angle φ and tensile strength at the same time,the distribution of the plastic zone is similar with the ultimate bearing capacity.Therefore,it is necessary to consider the effect of the tensile failure of gob area during the calculation of the safety factor and latent failure zone.
In order to study the gob area roof stability of Qidashan iron mine,the numerical software FLAC3D and limit analysis method were used to simulate the deformation and failure situation of the roof with different thickness under additional loading.In the simulation,the Mohr-Coulomb criterion was adopted,which can consider both the tensile and the shear failure of materials.The results show that when the roof thickness is less than 5.5 m,the tensile failure is the main mode.It will lead to the great increase of arch plastic zone areas.The strength reduction safety factor and the ultimate bearing capacity with the increasing roof thickness are not significant and have an approximately linear relationship.When the roof thickness is more than 5.5 m,the safety factor and ultimate bearing capacity are increased remarkably.The roof thickness is thus determined to be more than 5.5 m for the gob spacing of 10 m,which can ensure the roof stability under roof rock weight and additional loading.With the reduction of material parameters of cohesion c,internal friction angle φ and tensile strength at the same time,the distribution of the plastic zone is similar with the ultimate bearing capacity.Therefore,it is necessary to consider the effect of the tensile failure of gob area during the calculation of the safety factor and latent failure zone.
引文
[1]Swift G M,Reddish D J.Stability problems associated with anabandoned ironstone mine[J].Bulletin of EngineeringGeology and the Environment,2002,61(3):227-239.
[2]Nomikos P P,Sofianos A I,Tsoutrelis C E.Structuralresponse of vertically multi-jointed roof rock beams[J].International Journal of Rock Mechanics&MiningSciences,2002,39(1):79-94.
[3]林杭,曹平,李江腾,等.采空区临界安全顶板预测的厚度折减法[J].煤炭学报,2009,34(1):53-57.(Lin Hang,Cao Ping,Li Jiang-teng,et al.The thicknessreduction method in forecasting the critical safety roofthickness of gob area[J].Journal of China Coal Society,2009,34(1):53-57.)
[4]郑颖人,邱陈瑜,张红,等.关于土体隧洞围岩稳定性分析方法的探索[J].岩石力学与工程学报,2008,27(10):1969-1980.(Zheng Ying-ren,Qiu Chen-yu,Zhang Hong,et al.Exploration of stability analysis methods for surrounding rocksof soil tunnel[J].Chinese Journal of Rock Mechanics andEngineering,2008,27(10):1969-1980.)
[5]郑颖人,肖强,叶海林,等.地震隧洞稳定性分析探讨[J].岩石力学与工程学报,2010,29(6):1081-1088.(Zheng Ying-ren,Xiao Qiang,Ye Hai-lin,et al.Study oftunnel stability analysis with seismic load[J].Chinese Journalof Rock Mechanics and Engineering,2010,29(6):1081-1088.)
[6]Griffiths D V,Lane P A.Slope stability analysis by finiteelements[J].Geotechnique,1999,49(3):387-403.
[7]Dawson E M,Roth W H,Drescher A.Slope stability analysisby strength reduction[J].Geotechnique,1999,49(6):835-840.
[8]Itasca Consulting Group Inc.FLAC3D(fast Lagranginananalysis of continua in 3 dimensions)(version 3.0)[M].Minneapolis:Itasca Consulting Group Inc,2005.
[2]Nomikos P P,Sofianos A I,Tsoutrelis C E.Structuralresponse of vertically multi-jointed roof rock beams[J].International Journal of Rock Mechanics&MiningSciences,2002,39(1):79-94.
[3]林杭,曹平,李江腾,等.采空区临界安全顶板预测的厚度折减法[J].煤炭学报,2009,34(1):53-57.(Lin Hang,Cao Ping,Li Jiang-teng,et al.The thicknessreduction method in forecasting the critical safety roofthickness of gob area[J].Journal of China Coal Society,2009,34(1):53-57.)
[4]郑颖人,邱陈瑜,张红,等.关于土体隧洞围岩稳定性分析方法的探索[J].岩石力学与工程学报,2008,27(10):1969-1980.(Zheng Ying-ren,Qiu Chen-yu,Zhang Hong,et al.Exploration of stability analysis methods for surrounding rocksof soil tunnel[J].Chinese Journal of Rock Mechanics andEngineering,2008,27(10):1969-1980.)
[5]郑颖人,肖强,叶海林,等.地震隧洞稳定性分析探讨[J].岩石力学与工程学报,2010,29(6):1081-1088.(Zheng Ying-ren,Xiao Qiang,Ye Hai-lin,et al.Study oftunnel stability analysis with seismic load[J].Chinese Journalof Rock Mechanics and Engineering,2010,29(6):1081-1088.)
[6]Griffiths D V,Lane P A.Slope stability analysis by finiteelements[J].Geotechnique,1999,49(3):387-403.
[7]Dawson E M,Roth W H,Drescher A.Slope stability analysisby strength reduction[J].Geotechnique,1999,49(6):835-840.
[8]Itasca Consulting Group Inc.FLAC3D(fast Lagranginananalysis of continua in 3 dimensions)(version 3.0)[M].Minneapolis:Itasca Consulting Group Inc,2005.
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