冲击荷载下混凝土破坏过程的数值模拟
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摘要
目的探究冲击荷载作用下混凝土内部真实的破坏机理以及在不同应变率下混凝土强度随应变率的变化规律.方法基于离散单元法,采用细观二维梁-颗粒模型BPM(Beam-Particle Mode in Two Dimensions)模拟了三种不同应变率下混凝土材料的动态响应.结果从混凝土破坏图形可以看出,冲击荷载下混凝土的破坏过程实际上是混凝土内部的原生裂纹的激发、扩展、贯通直至整体结构的破坏.从混凝土应力-应变曲线可以看出,混凝土是率敏感性材料,其峰值应力和应变均随应变率的提高而增大.结论模拟结果和试验结果在达到峰值应力前的曲线基本吻合,说明梁-颗粒模型可以用来模拟混凝土在冲击荷载下的动态破坏,其结果是可靠和准确的.
In order to study the objective mechanics of failure under impact loading in concrete and the varying regulations between strength and strain rates,the dynamic fracture process of concrete under three different strain rates was simulated with the BPM(beam-particle mode in two dimensions) which was based on DEM(discrete element method).The fracture photographs suggest that the fracture process of concrete under dynamic impact is caused by the initiation,propagation and coalescence of cracks.Concrete is a rate-sensitive material whose peak value stress and strain increases with the improvement of strain rates from the curve of stress-strain.A comparison of the simulated results with experimental data before peak strain intensity shows that the BPM can be used to simulate the fracture process of concrete under dynamic impact and the results are credible and accurate.
In order to study the objective mechanics of failure under impact loading in concrete and the varying regulations between strength and strain rates,the dynamic fracture process of concrete under three different strain rates was simulated with the BPM(beam-particle mode in two dimensions) which was based on DEM(discrete element method).The fracture photographs suggest that the fracture process of concrete under dynamic impact is caused by the initiation,propagation and coalescence of cracks.Concrete is a rate-sensitive material whose peak value stress and strain increases with the improvement of strain rates from the curve of stress-strain.A comparison of the simulated results with experimental data before peak strain intensity shows that the BPM can be used to simulate the fracture process of concrete under dynamic impact and the results are credible and accurate.
引文
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[6]李兆霞.损伤力学及其应用[M].北京:科学出版社,2002.
[7]崔新壮,金青,李卫民.含初始损伤的水泥砂浆材料的动态本构关系研究[J].工程爆破,2001,2(7):1-4.
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[9]翟越,马国伟,赵均海.花岗岩和混凝土在单轴冲击压缩荷载下的动态性能比较[J].岩土力学与工程学报,2007,26(4):763-768.
[2]刑纪波.梁-颗粒模型导论[M].北京:地震工程出版社,1996.
[3]唐春安,朱万成.混凝土损伤与断裂—数值模拟[M].北京:科学出版社,2003.
[4]Cundall P A,SLrack ODL.A discrete numerical modelfor granular assembles[J].Geotechnique,1979,29(1):47-65.
[5]Zhu F S,Zhang D H,Xing J B.Numerical simulationof fracture process in anisotropic brittle material[C]//Computation Mechanics,Proceeding of the SixthWorld Congress on Computational Mechanics in Con-junction with the Second Asian-Pacific Congress onComputational Mechanics.Beijing:Tsinghua universitypress,2004:84.
[6]李兆霞.损伤力学及其应用[M].北京:科学出版社,2002.
[7]崔新壮,金青,李卫民.含初始损伤的水泥砂浆材料的动态本构关系研究[J].工程爆破,2001,2(7):1-4.
[8]Tedesco J W,Ross C A.Strain-rate-dependent con-stitutive equations for concrete[J].ASME Journal ofPressure Vessel Technology,1998,20(4):398-405.
[9]翟越,马国伟,赵均海.花岗岩和混凝土在单轴冲击压缩荷载下的动态性能比较[J].岩土力学与工程学报,2007,26(4):763-768.
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