筑坝堆石料的动模量阻尼比试验研究

为研究目前在土石坝工程中遇到的长石砂岩类堆石料的动力特性,采用大型高压多功能静动三轴试验机,对某面板堆石坝长石砂岩类堆石料进行了动模量与阻尼比试验研究。分析了围压对最大动模量、动剪切模量比和阻尼比的影响,并以Hardin-Drnevich 模型为基础,确定主堆石料、过渡料和垫层料3种坝料的动模量和阻尼比等特性参数。试验结果表明:动模量随着动剪切应变的增大逐渐衰减,最大动模量随围压的提高而增大,各种材料的动剪切模量比随着动剪切应变的增大而减小,变化趋势满足Hardin-Drnevich公式,有效固结围压越大,动剪切模量比随动剪切应变衰减的速率越慢;阻尼比随着动剪切应变的增大而增大,围压越大,阻尼比越小,变化趋势可用提出的修正的Hardin-Drnevich公式进行描述。研究成果可为土石坝抗震设计与动力稳定评价提供理论基础。

Experimental Study on Dynamic Modulus and Damping Ratio of Dam Rockfill Materials

In order to study the dynamic characteristics of feldspar sandstone rockfill materials in earth-rock dam project, we tested the dynamic modulus and damping ratio of feldspar sandstone rockfill materials of a face rockfill dam using large multi-function static dynamic triaxial apparatus. Through the test we obtained the influence of confining pressure on the maximum dynamic modulus, dynamic shear modulus ratio and damping ratio, and further determined the dynamic modulus and damping ratio of three kinds of rockfill materials, namely, main rockfill, transition material and cushion layer based on Hardin-Drnevich model. Results elucidated that the dynamic modulus declined gradually with the increase of dynamic strain; the maximum dynamic modulus increased with the rising of confining pressure; the dynamic shear modulus ratio of the three materials shrank with the increase of dynamic shear strain, and such shrinkage attenuated with the rising of effective consolidating confining pressure, which is consistent with the Hardin-Drnevich formula. The damping ratio augmented with the increase of dynamic shear strain, but reduced with the rising of confining pressure, which can also be described by the modified Hardin-Drnevich formula suggested in the paper. The research findings offer theoretical basis for seismic design and dynamic stability evaluation of earth-rock dams.