覆盖土层对水库心墙坝动力响应影响研究

Influence of Covering Soil Layer on the Dynamic Response of Reservoir Core Dam

为研究大河沿水库心墙坝动力响应特征受覆盖土层特征影响变化,采用COMSOL Multiphysics建立了心墙坝计算模型,并对覆盖层物理力学特征参数以及分布特征开展了计算分析。研究表明,覆盖层黏聚力特征参数愈大,坝体动力响应愈弱,当地震波峰值加速度增大,会削弱覆盖层黏聚力特征参数对动力响应影响;在覆盖层不同黏聚力特征参数方案中,坝体加速度响应变化具有差异性,且黏聚力参数低于24 kPa时具有显著二次突增特征。坝体主应力峰值随覆盖层黏聚力特征参数增大呈递减变化,覆盖层黏聚力特征参数可限制坝体主应力受地震波峰值加速度影响。地震波峰值加速度为0.1、0.2 g时,覆盖层厚度每递增10 m,坝体加速度响应均值分别平均下降18.4%、16.9%。此研究可为水库心墙坝结构动力响应计算及抗震设计提供参考。

In order to study the dynamic response characteristics of the core wall dam of the Daheyan Reservoir influenced by the characteristics of the overlying soil layer,a COMSOL Multiphysics calculation model for the core wall dam was established,and the physical and mechanical characteristic parameters and distribution characteristics of the covering soil layer were calculated and analyzed.The research shows that the larger the characteristic parameter of covering soil layer cohesionis,the weaker the dynamic response level of the dam bodyis.When the peak acceleration of seismic waves increases,the influence of the characteristic parameter of overburden cohesion on the dynamic response will be weakened.In the schemes with different cohesion characteristic parameters of the covering layer,there is a difference in the acceleration response level of the dam body,and there is a significant secondary sudden increase feature when the cohesion parameter is below 24 kPa.The peak value of main stress of dam body decreases with the increasing characteristic parameter of overburden cohesion,which can limit the influence of seismic peak acceleration on the main stress of dam body.When the peak acceleration of seismic wave is 0.1g and 0.2g,the average acceleration response of the dam body decreases by 18.4% and 16.9% respectively for every 10 m increase in the thickness of the overburden layer.The paper can provide reference for the dynamic response calculation and seismic design of reservoir core wall dam structures.