不同地基弹模对重力坝动力特性的影响研究
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摘要
基于有限单元法,采用振型分解反应谱法对龙滩水电站非溢流坝段在不同地基弹性模量下的动力特性进行了分析,研究了混凝土弹性模量与地基弹性模量的比值与坝体应力、位移、自振频率之间的关系,结果表明:①地基越柔坝体自振频率越小;②坝体位移随地基弹模的降低而增大;③坝体应力受地基弹模影响较大,特别是当混凝土弹性模量与地基弹性模量的比值较大时,尽管能减小坝踵处的拉应力,但坝踵和坝趾处也出现较大压应力;④混凝土弹性模量与地基弹性模量的比值在1.0与2.0之间对坝体动力特性影响相对较小。该结论可供设计、施工和同类工程参考。
The dynamic characteristics of the water retaining monolith of Longtan Hydropower Station is analyzed by the mode-superposition response spectrum method based on the finite element method(FEM) in different foundation elastic modulus.The relationship between stress,displacement,natural frequency and the ratio of elastic modulus of dam and its foundation is analyzed.It is concluded that:①The softer the foundation is,the smaller the natural frequency is;②The displacement of dams becomes large with the decrease in foundation elastic modulus;③ The foundation elastic modulus has a great influence on stress,especially when the ratio of elastic modulus of a dam and its foundation is large,although it can decrease the tension stress of dam heels,large compressive stress appears at dam heels and dam toes;④The ratio of elastic modulus of a dam and its foundation which is assumed to be between 1.0 and 2.0 has little influence on the dynamic characteristics of the dam.These conclusions serve as a reference in similar projects.
The dynamic characteristics of the water retaining monolith of Longtan Hydropower Station is analyzed by the mode-superposition response spectrum method based on the finite element method(FEM) in different foundation elastic modulus.The relationship between stress,displacement,natural frequency and the ratio of elastic modulus of dam and its foundation is analyzed.It is concluded that:①The softer the foundation is,the smaller the natural frequency is;②The displacement of dams becomes large with the decrease in foundation elastic modulus;③ The foundation elastic modulus has a great influence on stress,especially when the ratio of elastic modulus of a dam and its foundation is large,although it can decrease the tension stress of dam heels,large compressive stress appears at dam heels and dam toes;④The ratio of elastic modulus of a dam and its foundation which is assumed to be between 1.0 and 2.0 has little influence on the dynamic characteristics of the dam.These conclusions serve as a reference in similar projects.
引文
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[2]陈国桑.重力坝地基弹模及坝体异弹模对坝踵、坝趾应力的影响[J].水利学报,1981,1:62-70.
[3]王博,董耀星,王宗敏.重力坝与基岩弹模比的最佳点及安全区间概念[J].郑州工学院学报,1993,14(2):38-43.
[4]李宗坤,周鸿钧.地基弹性和坝踵裂缝对重力坝动力特性的影响[J].郑州工学院学报,1994,15(1):14-19.
[5]颜晓梅.重力坝溢流坝段动力特性及地震响应研究[D].武汉:武汉大学,2004.
[6]王韶国,岑肠龙,邱树艺,叶技能.不同地基弹模对拱坝坝体工作性态的影响[J].福州大学学报(自然科学版),1990,18(4):90-93.
[7]DL 5077-1997,水工建筑物荷载设计规范[S].
[8]郝文化.ANSYS土木工程应用实例[M].北京:中国水利水电出版社,2005.
[9]DL 5073-2000.水工建筑物抗震设计规范[S].
[10]DL 5108-1999.混凝土重力坝设计规范[S].
[11]林志文.汕头市北郊立交桥软弱地基处理方法的选择[J].探矿工程(岩土钻掘工程),2007,4:19-20.
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