三维落石模拟于明隧道载重问题之应用
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摘要
台湾山区落石灾害层出不穷,每逢地震事件或台风豪雨季节常引致山区落石灾害,而落石灾害程度因量体差异而有所区别,尤以大量岩块同时运动堆积所导致山区明隧道工程破坏最为严重,诸如中横沿线大规模落石导致明隧道破坏之灾害事件。回顾当前研究,前人多以集块质量法、二维分离元素法进行落石运动轨迹之模拟,并依据能量大小决定危险等级作为落石危害区划定之依据,却往往忽略了落石群同时运动产生交互作用,甚至二维与三维堆积分布差异,造成最终落石危害范围之影响。有鉴于此,本研究主要着重于落石群堆积模拟于探讨明隧道顶部载重之影响,应用小型室内物理模型配合分离元素法之颗粒力学仿真,针对不同量体岩块条件下进行其岩坡落石群堆积之力学行为模拟。藉此将相关力学模拟方法应用于实际落石灾害区,以期成为当前明隧道载重设计、相关技术规范及后续研究之参考依据。
Rockfall disasters occurred frequently in Taiwan mountain areas during the earthquake and storm events. The magnitudes of impact force on civil engineering structures depend significantly on the total rockfall volumes and the evolution of rockfall processes. Simultaneous fall of a larger rock block containing many fragments will transfer larger impact force on the rock shed than that of rock blocks with fragments gradually fall down in series. Most studies applied the Lumped Mass Approach (LMA) and two dimensional Discrete Element Method (DEM) to simulate trajectories and velocity of the rockfall movements. However, previous work often neglected that the interaction between fragments of a large falling block will cause fragments collisions and spreading, which will influence the concentration of impact force and the three dimensional effects of deposit pattern of rockfall. Therefore, this research focus on the impact force on the rock shed with varied evolution of rockfall processes. Numerical DEM program (PFC3D 3.0) calibrated with small scale physical rockfall experiment are used to simulate impact forces on rockfall shed and talus deposits. Subsequently, the valid numerical method is applied to full scale problem. The results are helpful for developing reasonable and scientifically sound base for technical code of rockfall problem.
Rockfall disasters occurred frequently in Taiwan mountain areas during the earthquake and storm events. The magnitudes of impact force on civil engineering structures depend significantly on the total rockfall volumes and the evolution of rockfall processes. Simultaneous fall of a larger rock block containing many fragments will transfer larger impact force on the rock shed than that of rock blocks with fragments gradually fall down in series. Most studies applied the Lumped Mass Approach (LMA) and two dimensional Discrete Element Method (DEM) to simulate trajectories and velocity of the rockfall movements. However, previous work often neglected that the interaction between fragments of a large falling block will cause fragments collisions and spreading, which will influence the concentration of impact force and the three dimensional effects of deposit pattern of rockfall. Therefore, this research focus on the impact force on the rock shed with varied evolution of rockfall processes. Numerical DEM program (PFC3D 3.0) calibrated with small scale physical rockfall experiment are used to simulate impact forces on rockfall shed and talus deposits. Subsequently, the valid numerical method is applied to full scale problem. The results are helpful for developing reasonable and scientifically sound base for technical code of rockfall problem.
引文
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[4]Cundall,P.A.and Strack,O.D.L..Adiscrete numerical model for granular assemblies.Geotechnique,1979,Vol.29:47-65.
[5]F.Delhomme,M.Mommessin,J.P.Mougin,P.Perrotin.Behavior of a structurally dissipating rock-shed:experi-mental analysis and study of punching effects.International Journal of Solids and Structures,2005,42:4204?4219.
[6]Philippe Berthet-Rambaud,Yehya Timsah,Laurent Daudeville,and Jacky Mazars.Finite element modeling of concrete protection structures submitted to rock impacts.16th ASCE Engineering Mechanics Conference,Seattle,University of Washington,2003:1?12.
[2]郑富书,林铭郎.岩石边坡之破坏与防治[J].土木工程技术,2001,5(3):1-28.
[3]台湾公路局九二一集集大地震灾害,中横公路灾情及抢修报告(台八线谷关-德基段)[R].台北,1999.
[4]Cundall,P.A.and Strack,O.D.L..Adiscrete numerical model for granular assemblies.Geotechnique,1979,Vol.29:47-65.
[5]F.Delhomme,M.Mommessin,J.P.Mougin,P.Perrotin.Behavior of a structurally dissipating rock-shed:experi-mental analysis and study of punching effects.International Journal of Solids and Structures,2005,42:4204?4219.
[6]Philippe Berthet-Rambaud,Yehya Timsah,Laurent Daudeville,and Jacky Mazars.Finite element modeling of concrete protection structures submitted to rock impacts.16th ASCE Engineering Mechanics Conference,Seattle,University of Washington,2003:1?12.
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