底部基座对重力坝强震破坏模式的影响  

Influence of Bottom Pedestal on Failure Mode of Gravity Dam under Strong Earthquake

作　　者：何卫平 刘聪宇 乐明锴 姚惠芹 HE Wei-ping;LIU Cong-yu;YUE Ming-kai;YAO Hui-qin(Hubei Key Laboratory of Construction and Management in Hydropower Engineering,China Three Gorges University,Yichang 443002,China;College of Hydraulic and Environmental Engineering,China Three Gorges University,Yichang 443002,China)

机构地区：[1]三峡大学湖北省水电工程施工与管理重点实验室,湖北宜昌443002 [2]三峡大学水利与环境学院,湖北宜昌443002

出　　处：《长江科学院院报》2024年第8期150-156,共7页Journal of Changjiang River Scientific Research Institute

基　　金：国家自然科学基金项目(51809152)。

摘　　要：我国西南地区某重力坝工程的左岸非溢流坝段采用独特的方形基座设计,考虑到该地区面临较高强震风险,评估底部基座对重力坝强震破坏模式和极限承载能力的影响十分必要。采用声学单元模拟库水,以弹塑性损伤模型模拟混凝土非线性特征,构建声固耦合-损伤模拟方法,并以Koyna重力坝为算例验证其可行性。随后以带基座坝段和常规坝段为对象,研究基座对重力坝强震破坏过程的影响。结果显示,带基座坝段与常规坝段均在上游折坡、坝踵、下游坝面区域出现破坏。底部基座对重力坝破坏过程的影响有:带基座坝段出现新的破坏区;底部基座有效减弱了坝踵破坏区的深度和面积;带基座坝段在下游坝面的破坏区出现2个发展方向。在抗震极限承载能力方面,常规坝段破坏区贯通对应地震动峰值加速度为0.50g~0.55g,带基座坝段提升至0.55g~0.60g,故底部基座设计提升了非溢流坝段的极限抗震承载能力。A unique square-bottom pedestal has been adopted in the non-overflow sections of a gravity dam in southwest China.Given the region’s susceptibility to severe earthquakes,the influence of the pedestal on the failure mode and the ultimate seismic resistance capacity of the gravity dam is investigated.An acoustic-solid-coupled damage simulation method is proposed with the acoustic element simulating the reservoir water and the elasto-plastic damage model reflecting the nonlinear characteristics of concrete.The feasibility of this method in predicting structural failure modes is verified by analyzing the Koyna gravity dam under the Koyna earthquake.Comparative analyses between the pedestal section and conventional section reveal similar failure areas in the upstream slope,dam heel,and downstream face.Specific impacts of the pedestal include:new failure zones in the pedestal section;effective reduction of depth and area of the failure zone at dam heel;and generation of two development paths in the downstream failure area of pedestal section.According to the criteria of failure area breakthrough,the ultimate ground motion peak acceleration is 0.50-0.55g for conventional section and 0.55-0.60g for the pedestal section.In conclusion,the bottom pedestal enhances the ultimate seismic resistance capacity of the non-overflow dam section.

关 键 词：混凝土重力坝 底部基座 声固耦合-损伤模拟方法 强震破坏模式 极限抗震承载能力 

分 类 号：TV312[水利工程—水工结构工程]