基于圆弧与平面滑动模式的上荆江崩岸过程模拟对比分析  

Comparison of Simulated Bank Erosion Processes in the Upper Jingjiang Reach Using the Circular and Planar Sliding Modes

作　　者：孙启航 夏军强[1] 邓珊珊[1] 周美蓉[1] 石林 SUN Qihang;XIA Junqiang;DENG Shanshan;ZHOU Meirong;SHI Lin(State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China;Hunan Institute of Water Resources and Hydropower Research,Changsha 410114,China)

机构地区：[1]武汉大学水资源与水电工程国家重点实验室,湖北武汉430072 [2]湖南省水利水电科学研究院,湖南长沙410006

出　　处：《应用基础与工程科学学报》2023年第1期38-51,共14页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(51725902,U2040215,52009095);湖南省重大水利科技专项(湘水科技[2017]230⁃39)。

摘　　要：基于平面滑动与圆弧滑动模式,构建了具有最危险滑动面搜索过程的崩岸概化模型.该模型耦合了坡脚冲淤、潜水位及河岸稳定性计算模块,其中圆弧滑动模式考虑了土体的垂向分层结构.采用该崩岸模型计算了2014年上荆江典型断面的崩岸过程,结果表明:在坡度较缓的断面,圆弧滑动模式的计算误差更小;在荆55断面,圆弧和平面滑动模式计算的崩塌次数分别为10次和2次,崩岸宽度的相对误差分别为21.5%和29.9%;在荆61断面分别为7次和1次,崩岸宽度的相对误差分别为1.0%和6.1%.最后开展了河岸土体参数的敏感性数值试验,分析了土体抗剪强度参数及土体垂向分层结构对崩岸过程的影响:随着抗剪强度参数的增加,模拟的总崩岸宽度呈减小趋势,单次崩岸宽度和崩岸次数的变化趋势与黏聚力及内摩擦角代表的力学特性有关;另外砂土层作为软弱夹层会通过增大单次崩岸宽度或崩岸次数来增加总崩岸宽度.A general bank erosion model at section⁃scale was proposed,based on the bank erosion modes of circular and planar sliding.The model adopts the most dangerous sliding surface method,and combines with the calculation modules of bank⁃toe erosion,change of underground water level and bank stability analysis,which can consider the bank⁃toe accumulation of failed bank soil in stability analysis and the vertical stratification structure of the bank soil for the mode of circular sliding.Using the proposed model based on the planar and circular sliding modes,the bank erosion processes at two typical sections of the upper Jingjiang Reach(Jing55 and Jing61)in 2014 were calculated.The results indicate that:(i)the simulated collapse numbers at Jing55 based on the circular and planar sliding modes were 10 times and 2 times,with the errors of 21.5%and 29.9%,respectively.The simulated collapse numbers at Jing61 were 7 times and 1 time according to these sliding modes,respectively,with the errors of 1.0%and 6.1%respectively.In general,the bank erosion modelling based on the circular sliding mode is more suitable for the sections with gentle slopes;and(ii)the sensitivity tests of relevant riverbank soil parameters were carried out.The influence of the vertical soil stratification structure on bank erosion was analyzed.With an increase in cohesion and internal friction angle,the simulated bank erosion width gradually decreased,and the variation trend of frequency and width of bank erosion was related to the physical soil properties.In addition,as a weak interlayer,the presence of sand layer can increase the total width of bank erosion by increasing the width of single collapse or the number of collapses.

关 键 词：河道崩岸 概化模型 失稳模式 平面滑动 圆弧滑动 垂向分层 上荆江 

分 类 号：TV147[水利工程—水力学及河流动力学]