三级配混凝土静、动载下力学细观破坏机制研究
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摘要
假定三级配混凝土是由砂浆基质、不同粒径的骨料及其粘结带组成的非均质复合材料,采用非线性有限元方法在细观尺度上数值模拟三级配混凝土弯拉梁在静、动载下的开裂过程。按实际配比计算各种骨料的代表粒径的数目,采用蒙特卡罗方法随机生成骨料分布,骨料形状假定为圆形,最小粒径为12.5mm。骨料、砂浆及其粘结带均采用了非线性本构模型,具体模拟了材料的开裂、拉伸软化、塑性屈服和压碎等非线性。研究中还给出了梁关键部位的应力应变全过程曲线,研究成果还与未考虑材料的非均质性的结果进行了比较。结果表明,混凝土类的多项非均质复合材料的静、动力学性能与其内部的细观结构组成有密切关系,混凝土中最薄弱的部位为粘结界面,混凝土的破坏明显表现出拉应变软化现象和局部化现象。数值模拟结果与有关试验成果较为接近。
The three-gradation concrete is taken as a three –phase composite consisting of mortar matrix, aggregate and bond between matrix and aggregate, and the cracking process of the three-gradation concrete beam specimen under static and dynamic loadings is analyzed with nonlinear finite element method at micro-scale level. The aggregates, following a predefined size distribution, are placed randomly in the specimen. The shape of the aggregates is approximated by circles and their minimum diameter is 12.5mm. Nonlinear constitutive relations are proposed to model cracking, softening, yielding and crushing of the composites. The full curves of stress and strain at the key location of the beam are given, and the results are also compared with that of homogeneous materials. The results from numerical simulation show that mechanical behaviors are directly related to the microstructure of concrete, and the interface is the weakest location where cracking usually occurs first. The failure process of concrete reveals that the phenomenon of tensile strain softening and localization is obvious, and the results of numerical analysis are very close to those of experiments.
The three-gradation concrete is taken as a three –phase composite consisting of mortar matrix, aggregate and bond between matrix and aggregate, and the cracking process of the three-gradation concrete beam specimen under static and dynamic loadings is analyzed with nonlinear finite element method at micro-scale level. The aggregates, following a predefined size distribution, are placed randomly in the specimen. The shape of the aggregates is approximated by circles and their minimum diameter is 12.5mm. Nonlinear constitutive relations are proposed to model cracking, softening, yielding and crushing of the composites. The full curves of stress and strain at the key location of the beam are given, and the results are also compared with that of homogeneous materials. The results from numerical simulation show that mechanical behaviors are directly related to the microstructure of concrete, and the interface is the weakest location where cracking usually occurs first. The failure process of concrete reveals that the phenomenon of tensile strain softening and localization is obvious, and the results of numerical analysis are very close to those of experiments.
引文
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[2]唐春安,朱万成.混凝土损伤与断裂—数值试验[M].北京:科学出版社,2003.Tang Chunan,Zhu Wancheng.Concrete damage and fracture-numerical simulation[M].Beijing:Science Press,2003.(in Chinese)
[3]Bazant Z P.Random particle model for fracture of aggregate or fiber composites[J].J.Engng.Mech.,1990,116(8):1686~1705.
[4]Schlangen E,Van Mier J G M.Simple lattice model for numerical simulation of fracture of concrete materials and structures[J].Materials and Structures,1992,25:534~542.
[5]Asai M,Terada K and Ikeda K.Meso-scopic concrete analysis with a lattice model[A].Fracture Mechanics of Concrete Structures[C].Edited by Rene de Borst,Swets and Zeitlinger,Lisse,2001.757~764.
[6]杨强,张浩,周维垣.基于格构模型的岩石类材料破坏过程的数值模拟[J].水利学报,2002,(4):46~50.Yang Qiang,Zhang Hao,Zhou Weiyuan.Lattice model for simulating failure process of rock[J].Journal of Hydraulic Engineering,2002,4:46~50.(in Chinese)
[7]H?rsch T and Wittmann F H.Three-dimensional numerical concrete applied to investigate effective properties of composite materials[A].Fracture Mechanics of Concrete Structures[C].Edited by Rene de Borst,Swets and Zeitlinger,Lisse,2001.57~64.
[8]王宝庭,宋玉普,张燕坤.基于刚体—弹簧模型的混凝土微裂纹行为模拟[J].工程力学,1999,16(2):140~144.Wang Baoting,Song Yupu,Zhang Yankun.Simulation of concrete micro-crack behavior using RBSM[J].Engineering Mechanics,1999,16(2):140~144.(in Chinese)
[9]刘光廷,王宗敏.用随机骨料模型数值模拟混凝土材料的断裂[J].清华大学学报(自然科学版),1996,36(1):84~89.Liu Guangting,Wang Zongmin.Numerical simulation ofconcrete fracture using random aggregate model[J].Journal of Tsinghua University(Science and Technology),1996,36(1):84~89.(in Chinese)
[10]彭一江,黎保琨,刘斌.碾压混凝土细观结构力学性能的数值模拟[J].水利学报,2001,6:19~22.Peng Yijiang,Li Baokun,Liu Bin.Numerical simulation of meso-level mechanical properties of roller compacted concrete[J].Journal of Hydraulic Engineering,2001,6:19~22.(in Chinese)
[11]尚岩.大体积混凝土静、动力学性能的数值模拟[D].南京:河海大学,2004.Shang Yan.Numerical simulation of mechanical behavior of mass concrete under static and dynamic load[D].Nanjing:Hohai University,2004.(in Chinese)
[12]杜成斌,马良筠,任青文.高拱坝的非线性地震响应分析[J].河海大学学报,1999,6:40~43.Du Chengbin,Ma Liangyun,Ren Qingwen.Nonlinear seismic response analysis of high arch dams with joints[J].Journal of Hohai University,1999,27(6):40~44.(in Chinese)
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