紫坪铺大坝下游坝坡震后抗震加固措施大型振动台模型试验研究
Large-scale shaking model tests on anti-seismic and reinforcing measures for slope of Zipingpu earth-rock fill dam after “5.12” Wenchuan Earthquake
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摘要: 紫坪铺水库面板堆石坝坝顶区下游干砌石护坡在汶川地震中遭到了较严重的震损破坏,是大坝震后抗震加固处理的重点环节。综合考虑已有高土石坝坝坡抗震加固措施在大坝震后加固中的适用性,并参考浆砌石护坡在强震中表现出的良好抗震性能,浆砌石护坡成为了紫坪铺大坝下游坝坡震后抗震加固的重要选择。针对紫坪铺大坝坝坡震后抗震加固工程,进行堆石坝坝顶区坝坡抗震加固措施(干砌石护坡和浆砌石护坡)大型振动台模型试验,研究砌石护坡的抗震加固机理并验证其抗震加固效果;同时,结合大坝地震动力反应计算和大坝振动台模型试验的研究成果,确定了大坝坝顶区浆砌石护坡的加固范围。研究表明:浆砌石护坡在强震中具有良好的整体性,干砌石护坡在强震中的局部碎、块石滑移导致护坡整体渐进破坏,浆砌石护坡对堆石坝坡的保护作用明显优于干砌石护坡;紫坪铺大坝下游坝坡震后浆砌石护坡加固范围取为3/4坝高以上坝顶区坝坡较为合理。Abstract: The dry masonry facing of the downstream slope of Zipingpu earth-rock fill dam was seriously destroyed during “5.12” Wenchuan Earthquake. Accordingly, the anti-seismic reinforcement for the damaged dam slope is an important task after the earthquake. The mortar masonry facing is regarded as the best choices comprehensively considering the applicability of anti-seismic and reinforcing measures for slopes of high earth-rock fill dams after earthquake proposed by worldwide engineers and its excellent anti-seismic performance in real strong earthquakes. Large-scale shaking table model tests on anti-seismic and reinforcing measures for earth-rock fill dam slope (dry masonry and mortar masonry facings) of Zipingpu earth-rock fill dam after “5.12” Wenchuan Earthquake are performed. The anti-seismic and reinforcing effect of the masonry facings is verified by the shaking model tests, and their anti-seismic and reinforcing mechanism is analyzed. Furthermore, the reinforcement area of the dam slope using the mortar masonry facing is determined based on the test results combining with the calculated results of the dam's earthquake response. The results show that the mortar masonry facing can keep its integrity wonderfully in strong earthquake, but the dry masonry facing may fail gradually because of the loosening and sliding of local stones in strong earthquakes. The protective effects of the mortar masonry facing on the dynamic stability of rock-fill dam slope in earthquake is better than the dry masonry facing obviously. The reinforcement area of the downstream slope of Zipingpu earth-rock fill dam using the mortar masonry facing after “5.12” Wenchuan Earthquake is determined to be in the dam slope area above 3/4 dam height.