Dynamic centrifuge modelling tests on seismic response of super-high core dams
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摘要: 通过4组相同几何比尺、不同加速度比尺的土工离心机振动台模型试验，采用外延分析方法，研究了某特高心墙坝最大坝高断面在设计地震作用下的坝体地震反应、坝顶变形、地震破坏模式。试验结果表明：设计地震下坝顶地震加速度放大系数约为2.97~3.03；3次地震作用下坝顶的沉陷率分别约为0.41%，0.56%，0.64%；随着地震次数的增加，坝顶沉降也增加，但沉降增量迅速减小；心墙的沉陷量最小，且没有任何坍塌迹象，总体稳定；下游坝体受地震影响较小，仅观察到轻微沉陷；地震主要引起上游堆石料的沉陷，且主要发生在第1次地震，而后越来越小；3次地震过程导致上游堆石料沉陷至蓄水位附近；没有观察到明显的堆石滚落现象。试验揭示的破坏现象说明，需要对坝顶处的堆石料进行加固，避免心墙暴露。Abstract: In order to study the seismic behaviors of a super-high core dam under design seismic intensity, 4 dynamic centrifuge modelling tests are carried out. The models have the same scale and different centrifugal accelerations. Thus, the acceleration response, deformation and stability are analyzed through the extrapolation analysis. The crest acceleration amplification factor is 2.97~3.03. The crest settlement rate is 0.41%, 0.56% and 0.64%, respectively under 3 design earthquakes. The total crest settlement increases, but the incremental settlement decreases rapidly with the number of earthquakes. The settlements of the core, downstream rockfill and upstream rockfill are greater than the former. The core is stable and the settlement of the downstream rockfill is slight. The earthquakes cause the settlement of the upstream rockfill to the storage level. The aseismic measures are necessary to provide the core from exposure according to the test results.
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Keywords:
- centrifuge shaking table /
- extrapolation analysis /
- super-high core dam /
- earthquake /
- failure mode
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图 1 装载了振动台的NHRI400 g·t大型离心机
Figure 1. NHRI 400 g·t centrifuge equipped with shaking table
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图 3 心墙坝轴线处加速度放大系数分布
Figure 3. Profile of acceleration amplification factor at dam axis
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图 4 坝顶地震加速度放大系数外延分析
Figure 4. Extrapolation analysis of acceleration amplification factors
表 1 离心机振动台技术指标
Table 1 Parameters of centrifuge shaking table
离心加速度 80g 频率 20~200 Hz 最大振动加速度 20g 激振波型 正弦波 最大位移 5 mm 地震波 最大有效负载 500 kg 随机波 最大振动时间 3 s 振动方向 水平振动 
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