300 m级高土石心墙坝流变特性研究

300 m级高土石心墙坝的流变特性对预判坝体竣工后长期变形及沉降具有重要的意义,对于研究防渗心墙能否适应坝体长期变形并正常工作亦至关重要。依托314 m高的双江口土石心墙坝工程,使用大型高压三轴仪对上、下游堆石料进行了流变特性试验研究,研究表明当最终的应力状态一致时,堆石料的流变按照分级加载和按照单级加载得到的流变曲线随着时间的发展差异性逐渐减小,最后基本趋于一致。在试验基础上,依据流变经验模型,得出了流变分析参数,并采用三维有限元法分析了300 m级土石心墙坝的流变特征。数值分析表明流变速率对坝体工后沉降幅度影响显著,由于试验中的流变速率较之现场坝料的实际流变情况明显偏快,因此流变速率的确定还有必要依据已建工程的反分析进行修正。

Creep deformation of 300 m-high earth core rockfill dam

For 300 m-high earth core rockfill dams, the creep characteristics of dam body have the vital significance in prediction of long-term deformation and settlement after dam construction. Meanwhile they are also very important to be used to evaluate whether or not the impervious core wall can match the long-term deformation of dams and keep on normal operation. Based on Shuangjiangkou Dam (314 m high, earth core rockfill dam), rockfill materials are tested by using a large high-pressure triaxial apparatus to study the creep characteristics. The results show that under multi-stage loading and single-stage loading, the difference of creep curves from the two tests decreases with the development of time when the tests have the same final stress state. And finally, the creep curves tend to converge. Using the empirical model for creep, the relevant parameters are obtained from the test data. The creep characteristics of 300 m-high earth core rockfill dam are analyzed by using the 3D finite element method. The numerical analysis shows that the creep velocity has a distinct influence on the settlement after dam construction. Compared with that of the actual creep conditions in dam body, the creep velocity in tests is much faster, so it’s necessary to make inverse analysis according to the built dams, which can provide an available method to amend the creep velocity.