软弱覆盖层上土石坝动力离心模型试验研究  

Dynamic centrifugal model tests on earth rock dam resting on soft overburden

作　　者：彭文明 张雪东 夏勇 PENG Wen-ming;ZHANG Xue-dong;XIA Yong(PowerChina Chengdu Engineering Corporation Limited,Chengdu,Sichuan 610072,China;Department of Hydraulic Engineering,Tsinghua University,Beijing 100084,China;Geotechnical Engineering Institute of China Institute of Water Resources and Hydropower Research,Beijing 100038,China)

机构地区：[1]中国电建集团成都勘测设计研究院有限公司,四川成都610072 [2]清华大学水利水电工程系,北京100084 [3]中国水利水电科学院岩土工程研究所,北京100038

出　　处：《岩土力学》2023年第6期1771-1778,共8页Rock and Soil Mechanics

摘　　要：在覆盖层上筑坝时其抗震稳定性是工程关键技术难点。为揭示覆盖层中的地震动传播规律和大坝失稳现象,依托某原型工程,先后输入场地波和加窗正弦波开展了离心机振动台模型试验。研究发现,在场地波目标峰值加速度0.53g激震时,因能量损耗和软弱覆盖层的滤波效应,地震动传播到坝顶的加速度峰值为0.773g,加速度放大系数为1.39,小于规范建议值2.0;在输入加窗正弦波的试验中,坝顶加速度放大系数为1.46,同样表明软弱覆盖层对地震动传播有一定衰减。两次试验揭示的大坝震陷变形现象符合一般规律,但因软弱砂层厚度大,总体震陷率较高,其中第1次试验后坝体没有明显的破坏,第2次试验出现大量堆石滚落、坝顶沉陷、坝坡挤压拱起、心墙开裂等现象。尽管受试验条件的限制,模型的尺寸效应和边界效应对试验结果可能存在一定影响,但该研究结论可为覆盖层上的坝体动力数值分析提供参考依据。The anti-seismic stability of dams built on overburden is a key challenge.In order to reveal the law of ground motion propagation in the overburden and the phenomenon of dam instability,centrifuge shaking table model tests were carried out by inputting site wave and windowed sine wave successively based on a prototype project.It is found that when the target peak acceleration of site wave is 0.53g,the peak acceleration of site wave transmitted to the dam crest is 0.773g and the acceleration amplification factor is 1.39 due to the energy loss and the filtering effect of the weak overburden.The acceleration amplification factor is less than the recommended value of 2.0 in the code.In the test of inputting windowed sine wave,the amplification factor of dam crest acceleration is 1.46,which also shows that the weak overburden has a certain attenuation effect on ground motion propagation.The dam seismic subsidence deformation revealed in the two tests conforms to the general law.However,due to the large thickness of the soft sand layer,the overall seismic subsidence rate is high.There is no obvious damage to the dam body after the first test,and some phenomena are observed such as a large number of rockfill falling,dam crest subsidence,dam slope extrusion arch,core wall cracking in the second test.Although limited by the test conditions,the size effect and boundary effect of the model may have some influence on the test results,some findings in the tests can provide a reference for the dynamically numerical simulation of dam resting on soft overburden.

关 键 词：软弱覆盖层 土石坝 地震动 动力离心模型试验 传播规律 

分 类 号：TU41[建筑科学—岩土工程]