基于改进人工鱼群算法的防渗墙结构优化研究

Research on Structural Optimization of Cutoff Walls Based on Improved Artificial Fish Swarm Algorithm

防渗墙是土石围堰中重要的防渗结构,对改善渗流场分布与提高土石围堰稳定性具有积极作用。为此,提出一种基于改进人工鱼群算法的防渗墙结构优化方法,以某围堰工程为例,基于有限元分析法建立围堰有限元模型,以防渗墙的墙体厚度和入岩深度作为待优化变量,构建以渗流量和经济指标联合表征的目标函数,采用改进人工鱼群算法更新待优化变量,确定最优的防渗墙结构,最后通过渗流—应力耦合分析,得到常水位和水位骤降工况下围堰的安全系数。结果表明,与传统人工鱼群算法相比,基于改进人工鱼群算法的防渗墙结构优化方法具有较快的收敛速度和收敛精度,优化后的防渗墙结构在满足防渗效果的前提下,实现了防渗效果和经济性的平衡;防渗墙后孔隙水压力下降明显,围堰在常水位及水位下降速率v=0.5、1.0、2.0 m/d工况下安全系数分别为1.489、1.410、1.376、1.321,均满足安全要求,体现了所提方法的可行性和合理性,研究结果可为土石围堰设计和施工提供参考。

Anti-seepage wall is an important anti-seepage structure in cofferdam,which plays an active role in improving the distribution of seepage field and the stability of cofferdam.This paper presents an optimization method of cutoff wall structure based on artificial fish optimization algorithm.Taking a cofferdam project as an example,the calculation model of cofferdam was established based on finite element analysis,and the wall thickness and rock depth of cutoff wall were taken as the variables to be optimized.Finally,the safety factor of cofferdam under the condition of constant water level and sudden drop of water level was obtained through seepage and stress coupling analysis.Compared with the traditional artificial fish swarm algorithm,the results show that the optimized method based on the improved artificial fish swarm algorithm has faster convergence speed and convergence accuracy,and the optimized anti-seepage wall structure can achieve the balance between the anti-seepage effect and the economy.The pore water pressure behind the cutoff wall decreased significantly,and the safety factors of the cofferdam under the conditions of constant water level and falling water level(falling rates are v=0.5 m/d,1.0 m/d and 2.0 m/d,respectively) were 1.489,1.410,1.376 and 1.321,which met the safety requirements,reflecting the feasibility and rationality of the proposed method.The research results can provide reference for the design and construction of cofferdam.