滚石坡面法向冲击动力响应特性研究
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摘要
滚石灾害是5.12地震诱发的主要次生山地灾害之一,因具有随机和不可预见性,成为灾后重建中地质灾害防治的难点。滚石防治的核心问题是解析滚石对坡面的冲击响应,由于冲击过程历时短、变形大和能量转换复杂,通过传统理论分析方法分析较为困难。为此,以Hertz理论为基础,考虑坡体的弹塑性特性,模型化滚石冲击为自由落体冲击的半无限体问题,运用动力有限元数值仿真技术,研究了滚石对坡面法向冲击特性,揭示滚石冲击速度、滚石半径对坡面土体动力响应的影响。结果显示基于弹塑性冲击理论的计算结果与数值模拟结果较为吻合,而完全弹性冲击理论的计算结果偏差较大,即基于弹塑性理论的滚石灾害防护设计更为合理。
As one of the most serious secondary mountain hazards of Wenchuan 8.0 Earthquake,the rock-fall is very hard to treat for its randomness and unpredictability.Based on the HERTZ theory,the characteristics of normal impact of rock-fall is studied by utilizing the finite element analysis software,ABAQUS.The analysis considers the elastic-plastic properties of slope materials and simplifies the impact as a mechanical problem of a sphere into a half-space loaded normally.Then the effect of impact velocity and radius of rock-fall on the dynamical response of slope is analyzed.The result shows that the values calculated by elastic-plastic theory agree well with the numerical simulations,while the results given by perfect elastic impact theory are much larger than the actual one,which indicates that the engineering design of rock-sheds based on elastic plastic theory would be more reasonable.
As one of the most serious secondary mountain hazards of Wenchuan 8.0 Earthquake,the rock-fall is very hard to treat for its randomness and unpredictability.Based on the HERTZ theory,the characteristics of normal impact of rock-fall is studied by utilizing the finite element analysis software,ABAQUS.The analysis considers the elastic-plastic properties of slope materials and simplifies the impact as a mechanical problem of a sphere into a half-space loaded normally.Then the effect of impact velocity and radius of rock-fall on the dynamical response of slope is analyzed.The result shows that the values calculated by elastic-plastic theory agree well with the numerical simulations,while the results given by perfect elastic impact theory are much larger than the actual one,which indicates that the engineering design of rock-sheds based on elastic plastic theory would be more reasonable.
引文
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[18]何思明,吴永,李新坡.颗粒弹塑性碰撞理论模型[J].工程力学,2008,25(12):19―24.He Siming,Wu Yong,Li Xinpo.Theory model on elastic-plastic granule impact[J].Engineering Mechanics,2008,25(12):19―24.(in Chinese)
[2]何思明,吴永,杨雪莲.滚石坡面冲击回弹规律研究[J].岩石力学与工程学报,2008,27(A01):2794―2798.He Siming,Wu Yong,Yang Xuelian.Study of rock-fall motion on slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(A01):2794―2798.(in Chinese)
[3]何思明,吴永,李新坡.滚石冲击碰撞恢复系数研究[J].岩土力学,2009,30(4):623―627.He Siming,Wu Yong,Li Xinpo.Research on restitution coefficient of rock fall[J].Rock and Soil Mechanics,2009,30(4):623―627.(in Chinese)
[4]何思明,李新坡,吴永.滚石冲击荷载作用下土体屈服特性研究[J].岩石力学与工程学报,2008,27(A01):2972―2977.He Simng,Li Xinpo,Wu Yong.Research on yield property of soil under rock-fall impact[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(A01):2972―2977.(in Chinese)
[5]沈均,何思明,吴永.滚石灾害研究现状及发展趋势[J].灾害学,2008,23(4):122―125.Shen Jun,He Siming,Wu Yong.Present research status and development trend of rockfall hazards[J].Journal of Catastrophology,2008,23(4):122―125.(in Chinese)
[6]Chan K S,Lee Y.A fracture mechanics-based model for assessing the mechanical failure of nuclear fuel rods due to rock fall[J].Nuclear Engineering and Design,2000,201:209―226.
[7]Chau K T,Wong R H C,Wu J J.Coefficient of restitution and rotational motions of rock-fall impacts[J].International Journal Rock Mechanics Mining Science&Geomechanism,2002,39:69―77.
[8]Baoquan A,Dwayne D.Discrete element method contact model for dynamic simulation of inelastic rock impact[J].Computers&Geosciences,2007,33:513―520.
[9]An B.A study of energy loss during rock impact using PFC2D[D].Edmonton:Thesis University of Alberta,2006.
[10]Delhomme F,Mommessin M,Mougin J P.Behavior of a structurally dissipating rock-shed:experimental analysis and study of punching effects[J].International Journal of Solids and Structures,2005,42(14):4204―4219.
[11]Kishi N,Konno H,Ikeda K.Prototype impact tests on ultimate impact resistance of PC rock-sheds[J].International Journal of Impact Engineering,2002,27(9):969―985.
[12]Pichler B,Hellmich Ch,Mang H A.Impact of rocks onto gravel Design and evaluation of experiments[J].International Journal of Impact Engineering,2005,31:559―578.
[13]Johnson K L.Contact mechanics[M].Cambridge:Cambridge University Press,1985.
[14]Baolin W,Drummond S C.A simplified approach for rockfall ground penetration and impact stress calculations[J].Landslides,2008,5:305―310.
[15]Brizmer V,Kligerman Y,Etsion I.The effect of contact conditions and material properties on the elasticity terminus of a spherical contact[J].International Journal of Solids and Structures,2006,43:5736―5749.
[16]Thornton C.Coefficient of restitution for collinear collisions of elastic perfectly plastic spheres[J].American Society of Mechanical Engineers Journal of Applied Mechanics,1997,64:383―386.
[17]Thornton C.Ning Z.A theoretical model for the stick/bounce behavior of adhesive,elastic–plastic spheres[J].Powder Technology,1998,99:154―162.
[18]何思明,吴永,李新坡.颗粒弹塑性碰撞理论模型[J].工程力学,2008,25(12):19―24.He Siming,Wu Yong,Li Xinpo.Theory model on elastic-plastic granule impact[J].Engineering Mechanics,2008,25(12):19―24.(in Chinese)
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