心墙堆石坝坝顶加筋措施的动力离心模型试验研究

Examining the performance of geo-grid reinforcement using dynamic centrifuge tests

坝顶加筋是心墙堆石坝抗震的重要工程措施之一,然而目前对其抗震效果的试验研究并不充分。本文利用中国水科院双向离心机振动台开展了动力离心模型试验,探究了铺设土工格栅加固坝顶这一措施的抗震效果,并探讨了埋设间距及土工格栅材料刚度对心墙堆石坝动力响应的影响。动力离心模型试验结果表明,坝顶加筋提高了坝顶刚度,导致坝顶附近区域顺河向和竖向动力响应变强。采用0.08H至0.16H间距加筋都将起到增强坝体刚度、提高坝体抗震稳定性的作用,坝顶加筋降低震陷、裂缝等风险,有利于坝体的安全稳定。土工格栅的刚度对心墙堆石坝的动力响应影响较大,刚度过大的材料难以造成土料与土工格栅的紧密结合,从而不能起到良好的抗震效果。

Reinforcing the zone near the crest using geo-grid is one of the seismic engineering measures for earth core rockfill dams. However, there lacks experimental study on the seismic response of the reinforced dams. In order to assess the performance of geo-grid reinforcement, a series of centrifuge dynamic tests was performed using the IWHR (China Institute of Water Resources and Hydropower Research) horizontal-vertical shaker. The influence of the vertical spacing between geo-grid layers and the stiffness of geo-grid materials on the seismic response has been investigated. The results of the dynamic centrifuge tests indicate that the stiffness has been increased in the zone near dam crest by geo-grid reinforcement. This leads to stronger seismic response in both upstream-downstream and vertical directions. In addition, the seismic resistance of the dam can be increased by placing geo-grid in a spacing of 0.08H^0.16H. Moreover, the stiffness of the geo-grid has a strong influence on the seismic resistance. If the geo-grid is too strong, the coupling between geo-grid and soil cannot be maintained, and thas the performance of geo-grid reinforcement cannot be satisfying.