武都重力坝碾压混凝土动态弯拉性能的试验研究与数值分析
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摘要
武都水库是涪江干流上的一座重要工程,坝体设计为碾压混凝土重力坝。对武都重力坝工程的二级配、三级配碾压混凝土芯样试件采用简支梁三分点加载法,在不同初始静载下进行混凝土动态弯拉试验,并采用细观力学和损伤力学的方法进行混凝土弯拉强度和破坏过程的非线性分析。研究表明,不同级配混凝土受初始静载、加载速率的影响不同。在初始静载达到80%范围内,二级配混凝土动强度随初始静载比例的提高有所提高,动态强度提高因子为1.45~1.53;三级配混凝土动强度随初始静载比例的提高有所降低,动态强度提高因子为1.27~1.41。武都重力坝碾压混凝土存在一定的超强现象。与各初始预静载相应的混凝土动态弯拉强度提高因子的计算值与试验值比较接近。
The Wudu Reservoir is an important project on Fujiang River,whose dam is designed to be a roller compacted concrete(RCC) gravity dam.The flexural bending test for two-graded and three-graded RCC prism core samples of the Wudu RCC Gravity Dam under different initial static load cases were carried out.At the same time the flexural strength of concrete and the crack expanding process were analyzed by the methods of meso-mechanics and damage mechanics.The test results indicate that the strength of concrete with different kinds of grade is influenced by the initial static loads and the load speed in different degrees.For the two-graded concrete,the dynamic strength amplification factors fall into a range between 1.45 and 1.53 under different pre-static loads,the dynamic strength increases with the increase of the initial static load ratio when the initial static load is up to within 80%.For the three-graded concrete,the dynamic strength amplification factors fall into a range between 1.27 and 1.41 under different pre-static loads and the dynamic strength decreases with the increase of the initial static load ratio when the initial static load is up to within 80%.The concrete of Wudu RCC Gravity Dam is somewhat over-strengthened.The calculated results of the dynamic flexural strength amplification factors under different initial loads are approximate to the test results.
The Wudu Reservoir is an important project on Fujiang River,whose dam is designed to be a roller compacted concrete(RCC) gravity dam.The flexural bending test for two-graded and three-graded RCC prism core samples of the Wudu RCC Gravity Dam under different initial static load cases were carried out.At the same time the flexural strength of concrete and the crack expanding process were analyzed by the methods of meso-mechanics and damage mechanics.The test results indicate that the strength of concrete with different kinds of grade is influenced by the initial static loads and the load speed in different degrees.For the two-graded concrete,the dynamic strength amplification factors fall into a range between 1.45 and 1.53 under different pre-static loads,the dynamic strength increases with the increase of the initial static load ratio when the initial static load is up to within 80%.For the three-graded concrete,the dynamic strength amplification factors fall into a range between 1.27 and 1.41 under different pre-static loads and the dynamic strength decreases with the increase of the initial static load ratio when the initial static load is up to within 80%.The concrete of Wudu RCC Gravity Dam is somewhat over-strengthened.The calculated results of the dynamic flexural strength amplification factors under different initial loads are approximate to the test results.
引文
[1]中国水电顾问集团贵阳勘测设计研究院.四川武都水库碾压混凝土大坝5.12震后检测报告[R].贵阳:贵阳勘测设计研究院,2008.
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[2]Bicanic N,Zienkiewicz O C.Constitutive model for concrete under dynamic loading[J].Earthquake Engineeringand Structural Dynamics,1983,11(2):689-711.
[3]Rossi P.A physical phenomenon which can explain the mechanical behaviour of concrete under high strain rates[J].Materials and Structures,1991,24(144):422-424.
[4]Bischoff P H,Perry S H.Impact behavior of plain concrete loaded in uniaxial compression[J].Journal of Engi neering Mechanics,1995,121(6):685-693.
[5]董毓利,谢和平,赵鹏.不同应变率下混凝土受压全过程的试验研究及其本构模型[J].水利学报,1997(7):72-77.
[6]国家电力公司昆明勘测设计研究院.高坝工程技术研究—高拱坝地震应力控制标准和抗震工程措施研究[R].昆明:昆明勘测设计研究院,2000.
[7]中国水利水电科学研究院,等.全级配大坝混凝土动态性能研究[R].北京:中国水利水电科学研究院,2002.
[8]DL5073-1997,水工建筑物抗震设计规范[S].
[9]马怀发,陈厚群,黎保琨.混凝土试件细观结构的数值模拟[J].水利学报,2004,35(10):27-35.
[10]马怀发,陈厚群,黎保琨.应变率效应对混凝土动载弯拉强度的影响[J].水利学报,2005,36(1):69-76.
[11]SL352-2006,水工混凝土试验规程[S].
[12]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.
[13]马怀发,陈厚群.全级配大坝混凝土动态损伤破坏机理研究及其细观力学分析方法[M].北京:中国水利水电出版社,2008.
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