高心墙堆石坝坝坡加筋抗震稳定分析

目前强震区高土石坝抗震设计普遍采用加筋技术加固坝顶堆石,但加筋的效果如何评价是工程设计者关心的重要问题。传统的基于极限平衡的拟静力法无法反映坝体的动力特性及地震输入特性,得到的安全系数也不反映加筋坝体抗震的安全度。采用改进的Newmark滑块位移法对加筋堆石改善高坝坝坡的抗震稳定性,限制高土石坝地震变形等的工程效果进行了研究和探讨。计算中,首先依据堆石体和加筋堆石体的应力应变关系曲线得筋材与堆石的协调极限应变,进而确定筋材所能发挥的极限抗拉强度,利用瑞典-荷兰法结合蚁群复合形法搜索堆石加筋复合体潜在滑动体的位置,考虑竖向地震以及筋材与堆石的相互作用对滑动体屈服加速度的影响,改进了Newmark滑块位移法。结果表明,加筋减少地震变形最高可达80%,可有效地限制高土石坝坝顶的侧向滑动变形,提高坝体的抗震稳定性。

Aseismic stability analysis for reinforced slopes of high core rock-fill dams

The reinforcement techniques have been widely adopted in modern aseismic design of high rock-fill dams.Nevertheless,how to evaluate the effects of reinforcement in aseismic design have become a very important problem.As compared with the minimum safety factors which were conventionally employed as the evaluation standard,the permanent deformation can better reflect the characteristics of rock-fill materials,ground motion input and the safety of reinforced dams.By use of the modified Newmark's sliding wedge method,the effect of reinforcement in enhancing the stability of slopes in high rock-fill dams and restricting the permanent deformation of dams was investigated.Firstly,the limit intensity and limit strain of reinforcement were determined based on the stress-strain relationship of reinforcement-composite and rock-fill materials.Secondly,the location of potential sliding surfaces was determined via a combination of ant colony algorithm and Fellenius method.The yielding acceleration of potential sliding bodies considering of the limited stress of reinforcement layers and vertical acceleration was computed.Finally,the transient movements were accumulated under the overloadings.It was shown that the reinforcement could reduce the permanent deformation up to 80% and improve the aseismic stability of high rock-fill dams subjected to strong ground motion effectively.