下游折坡点位置对重力坝抗震性能的影响
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摘要
为分析重力坝下游折坡点位置对其抗震性能的影响,从震害工程及有限元计算两方面分析重力坝的抗震性能。结果表明:下游折坡点位置过低将对重力坝抗震性能带来不利影响;坝颈部位应力随下游折坡点位置的降低而增大,且增幅随坝高的增加而增大。为保证大坝具有良好的抗震性能,工程设计中下游折坡点位置不宜取太低,在8度及以上地震烈度区,100 m高重力坝折坡点位置不宜低于坝高的20%。云南某水电站水库计算结果表明:大坝在设计地震作用下,坝颈部位产生了明显的应力集中,并出现裂缝;当地震超载系数为1.17时,坝颈部位上下游的裂缝贯通,大坝抗震性能较差,在工程设计中应合理提高下游折坡点的位置。
The influence of the downstream turning point on the seismic performance of a gravity dam was studied through earthquake projects and finite element calculation.The results show that a position of the downstream turning point that was too low had adverse effects on the seismic performance of the gravity dam.The stress of the neck of the dam increased with the descending position of the downstream turning point and the ascending height of the dam.To ensure good seismic performance of the dam,the position of the downstream turning point should not be too low in project design;it should not be lower than 20% of the height of the dam for a 100 m-high gravity dam in areas with an earthquake intensity of eight or an even higher degree.Linear elastic and nonlinear dynamic finite element analysis were conducted for a practical project in a hydropower station in Yunnan Province.The calculation results show that,under the design earthquake effects,obvious stress concentration and cracks appeared in the neck of the dam.When the earthquake overload coefficient was 1.17,the upstream cracks joined the downstream cracks in the neck of the dam,indicating that the seismic performance of the dam was very poor.The downstream turning point should be reasonably improved in project design.
The influence of the downstream turning point on the seismic performance of a gravity dam was studied through earthquake projects and finite element calculation.The results show that a position of the downstream turning point that was too low had adverse effects on the seismic performance of the gravity dam.The stress of the neck of the dam increased with the descending position of the downstream turning point and the ascending height of the dam.To ensure good seismic performance of the dam,the position of the downstream turning point should not be too low in project design;it should not be lower than 20% of the height of the dam for a 100 m-high gravity dam in areas with an earthquake intensity of eight or an even higher degree.Linear elastic and nonlinear dynamic finite element analysis were conducted for a practical project in a hydropower station in Yunnan Province.The calculation results show that,under the design earthquake effects,obvious stress concentration and cracks appeared in the neck of the dam.When the earthquake overload coefficient was 1.17,the upstream cracks joined the downstream cracks in the neck of the dam,indicating that the seismic performance of the dam was very poor.The downstream turning point should be reasonably improved in project design.
引文
[1]陈胜宏,陈敏林,赖国伟.水工建筑物[M].北京:水利水电出版社,2004.
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[10]GHAEMIAN M,GHOBARAH A.Seismic response of the Sefid-rud concrete buttressdam[J].Euro Earthquake Engineering,1997(1):7-16.
[11]林皋,陈健云.混凝土大坝的抗震安全评价[J].水利学报,2001,32(2):8-15.(LIN Gao,CHEN Jianyun.Seismic safety evaluation of large concrete dams[J].Journal of Hydraulic Engineering,2001,32(2):8-15.(in Chinese))
[12]周星德,章青,吴继敏,等.一种提高重力坝抗震性能的方法[J].水利水电科技进展,2011,31(3):31-33.(ZHOU Xingde,ZHANG Qing,WU Jimin,et al.Method to improve anti-seismic performance of gravity dams[J].Advances in Science and Technology of Water Resources,2011,31(3):31-33.(in Chinese))
[13]GB18306—2001中国地震动参数区划图[S].
[2]王良琛.混凝土坝地震动力分析[M].北京:地震出版社,1981.
[3]潘家铮.重力坝设计[M].北京:水利电力出版社,1987.
[4]朱伯芳,杨波.混凝土坝耐强震而不跨的机理[J].水利水电技术,2009,40(1):51-57.(ZHU Bofang,YANG Bo.The reason why concrete dams can resist strong earthquakes without serious damage[J].Water Resources and Hydropower Engineering,2009,40(1):51-57.(in Chinese))
[5]倪汉根,金崇磐.大坝抗震特性与抗震计算[M].大连:大连理工大学出版社,1994.
[6]陈厚群.混凝土高坝强震震例分析和启迪[J].水利学报,2009,40(1):10-18.(CHEN Houqun.Analysis on damages of high concrete dams subjected to strong earthquake and lessons for learning[J].Journal of Hydraulic Engineering,2009,40(1):10-18.(in Chinese))
[7]徐艳杰,牟海磊,张楚汉,等.汶川地震中宝珠寺重力坝地震响应的三维有限元模拟[J].地球物理学报,2012,55(1):293-302.(XU Yanjie,MU Hailei,ZHANG Chuhan,et al.3D finite element modeling of seismic responses of Baozhusi gravity dam in MS8.0 Wenchuan Earthquake[J].Chines Journal of Geophysics,2012,55(1):293-302.(in Chinese))
[8]陈厚群.汶川地震后对大坝抗震安全的思考[J].中国工程科学,2009,11(6):44-53.(CHEN Houqun.Consideration on seismic safety of dams in China after the Wenchuan Earthquake[J].Engineering Sciences,2009,11(6):44-53.(in Chinese))
[9]GHAEMIAN M,GHOBARAH A.Nonlinear seismic response of concrete gravity dams with dam-reservoir interaction[J].Engineering Structures,1999,21(4):306-315.
[10]GHAEMIAN M,GHOBARAH A.Seismic response of the Sefid-rud concrete buttressdam[J].Euro Earthquake Engineering,1997(1):7-16.
[11]林皋,陈健云.混凝土大坝的抗震安全评价[J].水利学报,2001,32(2):8-15.(LIN Gao,CHEN Jianyun.Seismic safety evaluation of large concrete dams[J].Journal of Hydraulic Engineering,2001,32(2):8-15.(in Chinese))
[12]周星德,章青,吴继敏,等.一种提高重力坝抗震性能的方法[J].水利水电科技进展,2011,31(3):31-33.(ZHOU Xingde,ZHANG Qing,WU Jimin,et al.Method to improve anti-seismic performance of gravity dams[J].Advances in Science and Technology of Water Resources,2011,31(3):31-33.(in Chinese))
[13]GB18306—2001中国地震动参数区划图[S].
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