摘要
围填海工程建于软土地基上,海堤易产生不规则沉降甚至坍塌,而在高水位期间可能发生溃堤灾害。本文采用HLL逼近Riemann解格式计算界面通量和有限体积法离散控制方程建立了数学模型,对围填海工程溃堤洪水运动进行模拟研究。针对浙南某围填海工程,成功模拟了海塘不同位置发生溃堤时的洪水演进过程:溃堤初始时刻,围区内淹没面积和淹没水深增长迅速,其后洪水推进速度放缓,平均水深则经历下降、快速增长、缓慢增长3个阶段变化;并且南堤溃决事故下同时刻平均水深较东堤溃决时高0.3～0.5m,其洪水灾害性和风险性更高。进一步分析双溃口条件下淹没水深的空间分布及其变化规律可知,洪水完全淹没围填海区仅需要60min,溃堤4h后淹没水深可达1.7m,围区东、南部两股水流迅速交汇将会造成较大的人员伤亡,其他区域居民可有15min以上逃生时间。另外,糙率参数在±15%区间变化下,计算平均水深最大变幅为20%,淹没面积最大变幅为14%。研究成果对于减少溃堤突发事故损失,提高工程建设管理水平具有重要现实意义,可为今后围填海工程的安全设计和风险评估提供技术依据。
Study on sea dikes breaching flood of the reclamation was carried out by means of numerical simulation in this thesis. The numerical model was based on the finite volume algorithm, which applied the HLL approximate Riemann solver to compute the numerical flux. A computational case study was presented of the flooding in a reclamation project of Zhejiang, where the flooded area and depth varying with time were obtained. The boundary condition of sea dikes breaching flow was taken by a constant water level, which is 20-year high tide level combined with the same frequency maximum wave height under the most unfavorable conditions. The model simulated the flooding in different locations of sea dikes failure successfully and the result shows that the submerged area and submerged depth rises quickly at the beginning of sea dikes breaching, and then the advance speed of flood tends to slow down, the average depth is followed by three stages of development： a slight decline, a dramatic rise and a small increase. The average depth for the south dike breaching flood is higher than that under the east dike-break case by 0.3~0.5 m at the same moment, so is the catastrophe and risk. The movement of flood caused by double breaching locations was further analysed. The flood spends only 60 minutes to overwhelm the reclamation, and the submerged depth rises to 1.7 m after 4 hours. In the southeast, the convergence area between two sea dikes breaching flow, heavy personnel casualty will he caused, but the people in the rest area will have 15 minutes to escape the flood. In addition, the impact of roughness range from plus 15 per cent to minus 15 per cent on the flood was discussed. It is concluded that the differences between the maximum and minimum of average depth and submerged area reached 20 and 14 percent, respectively. This research will be of great practical significance to reduce the loss of sea dikes breaching accident as well as raise the management standard in the construction period and running period, which aims to provide the base of safety design and risk assessment of reclamation project.
出处
《海洋学研究》
北大核心
2012年第3期92-98,共7页
Journal of Marine Sciences
基金
浙江省重大专项基金资助项目(2009C03008-1)
关键词
围填海
海塘溃决
洪水演进
数学模型
reclamation
sea dikes breaching
flood
mathematical model
