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崩岸是上荆江河段河床变形过程的一个重要方面,它与近岸水流冲刷及河岸土体特性等因素密切相关.三峡工程运用后该河段河床冲刷下切显著,导致局部河段的崩岸现象较为突出.本文改进了河岸崩退过程的概化模型,耦合了坡脚冲刷、潜水位变化及河岸稳定性计算模块,并在稳定性分析中考虑了侧向水压力、孔隙水压力及非饱和土体基质吸力的作用.采用该模型计算了2005年上荆江典型断面(荆34和荆55)的崩岸过程,计算结果表明:这两个断面的河岸分别发生6次和4次崩塌,且多发生于洪峰期和退水期;总崩退宽度为27和20 m,且计算与实测的岸坡形态较为符合.最后开展了相关河岸土体参数的敏感性数值试验,分析了土体物理力学特性变化对崩岸过程的影响:河岸崩退次数、宽度总体上随土体抗剪强度及渗透系数的增大而减小,前者基本呈单向变化,而后者还与崩塌时坡脚的冲刷幅度有关;此外潜水位滞后于河道水位的变化特点,降低了退水期的河岸稳定性.
Bank collapse is an important aspect of the river bed deformation process in the Jingjiang reach, which is closely related to the erosion of nearshore flow and the characteristics of riparian soil etc .. After the Three Gorges Project is applied, riverbed erosion and cutting are significant, resulting in the collapse of the bank The phenomenon is more prominent.This paper improves the general model of bank collapse process, coupled with the slope foot scouring, diving potential change and bank stability calculation module, and in the stability analysis to consider the lateral water pressure, pore water pressure and non- This model was used to calculate the collapse process of the Jingjiang typical section (Jing 34 and Jing 55) in 2005. The calculation results show that there are 6 and 4 collapses on the banks of the two sections respectively, And occurred mostly in the peak flood season and the retreat period.The total collapse width was 27 and 20 m, and the calculated and measured slope shape was more consistent.Finally, the sensitive numerical test of the relevant bank soil parameters was carried out, The influence of physical and mechanical characteristics on the process of bank collapse: The number and width of river bank collapse generally decrease with the increase of shear strength and permeability coefficient of soil, the former is basically a one-way change, while the latter also with slope collapse For scouring amplitude; in addition to a change in the characteristics of the hysteresis phreatic water levels, reducing the stability of the banks of the recession.