空间差异性下沥青混凝土心墙坝应力与变形的随机有限元分析

以往沥青混凝土心墙坝有限元分析通常采用筑坝材料的设计值进行计算,但实际施工质量的不确定性,使得筑坝材料在空间上表现出差异性。在考虑坝体与覆盖层材料空间差异性的情况下,提出了基于随机有限元沥青混凝土心墙坝应力、变形不确定性的分析方法。利用蒙特卡罗方法,得到了沥青混凝土心墙坝应力、变形的分布规律,并与设计工况下的有限元结果对比,确定考虑空间差异性对坝体与心墙应力、变形的影响以及应力、变形的超标概率。经分析发现:采用确定性的分析方法会有50%的可能性低估坝体最大沉降;43%的可能性低估坝体大主应力最大值;空间差异性下心墙不同位置处的沉降均有50%的超标概率,并且其下部的主应力超标概率会更大。分析成果可为大坝安全分析与设计优化提供依据,也为大坝的精细有限元分析提供了新的途径。

Stress and Deformation of Asphalt Concrete Core Wall Dam in Consideration of Spatial Difference: Stochastic Finite Element Analysis

Previous finite element calculation of asphalt concrete core wall dam is usually performed according to the designed parameters of dam material. However, due to the uncertainty of actual construction quality, the parameters of dam material differ in space. In consideration of such spatial difference, a stochastic finite element analysis method based on Monte-Carlo method is proposed for the stress and deformation of asphalt concrete core wall dam. The distributions of stress and deformation of asphalt concrete core wall dam are obtained and compared with those in designed condition. The impact of spatial difference on stress and deformation is examined, and the probabilities of stress and deformation exceeding those in designed condition are determined as well. Results reveal that deterministic analysis method underestimates the stress and deformation of dam with a 50% probability and the maximum principal stress with a 43% probability; while the result of the present method has a 50% probability of exceeding the designed value in terms of settlement at different positions, and even larger probability in principal stress. The research achievements offer reference for dam safety analysis and design optimization, and can be regarded as a new approach for fine finite element analysis of dam.