混凝土高坝仿真分析的混合算法

我国混凝土坝最大高度已达300 m,由于应力水平高,高坝应力比较重要,需进行仿真分析,笔者提出的分区异步长算法。可使仿真计算的时间减少,计算效率提高,本文提出混凝土高坝仿真分析的混合算法,即在仿真分析中,温度场采用常规有限元算法,应力场采用分区异步长算法。由于温度场计算本来就比较快,而且计算条件较复杂,采用常规算法,程序较简单,费时也不多。应力场计算量大,采用分区异步长算法,可有效节省计算时间,本文提出的混合算法兼顾了计算精度与计算效率两方面的要求。

Mixed method for computing the visco-elastic thermal streses in mass concrete

In low concrete dams,the stresses are so small that the safety of the dam is primarily dependent on the sliding stability. In high concrete dam, the stresses are large,so the safety of dam is dependent not only on the sliding stability but also on the stresses of the dam. For a concrete dam with 300 m of height,the duration of construction may be 2~3 years. Due to variations of ambient temperature of air and water,the process of construction has important influence on the stress state,thus it is necessary to conduct simulating computation of the stress field of the dam which is constructed layer by layer with thickness of 1.5~3.0 m. For a high concrete dam,the time of computing is rather long. By the method of different time increments in different regions［1,2］ ,the computing time is reduced but the program is somewhat complicated. For the node i,there is only one variable Ti in the temperature field,but there are three variable ui、vi、wi in the displacement field,so the most part of computing time is used for computing of stresses and only a little part of computing time is used for computing of temperatures. Due to this fact,the mixed method is proposed in this paper. The temperature field is computed by the common finite element method with good precision and the stress field is computed by the method of different time increments in different regions with high efficiency of computing. Thus,the mixed method has good precision as well as high efficiency of computing.