CAJ | 학술논문

三峡水库蓄水后，上荆江河段来沙急剧减少，河床冲刷下切，局部河段崩岸现象时有发生，影响两岸堤防安全。通常认为水流冲积作用是崩岸的主要控制因素，但已有研究表明，河道内水位变化能改变河岸土体的力学特性及受力条件，进而对崩岸过程产生较大影响。本文将一维非稳定渗流计算及黏性土河岸稳定性计算结合，构建了考虑潜水位变化的岸坡稳定性分析模型，用于计算河道内水位变化时岸坡稳定程度的调整过程。以上荆江河段荆34、公2断面为研究对象，采用该模型计算了2009年实测河道水位过程下相应断面的岸坡稳定安全系数Fs。结果表明：涨水期河岸稳定性较高，洪峰期有所降低，退水期更低；荆34、公2断面最小Fs值分别为0.83、1.39，均发生在退水期，表明前者在该时期会发生崩岸，后者较为稳定，这与实测资料相符。此外还计算了不同河道内水位变化速率下Fs值的变化过程，结果表明：岸坡稳定性在涨水速率增加时增大，在退水速率增加时则减小。因此近期上荆江河段崩岸加剧一定程度上与三峡工程运用后退水过程加快有关。
삼협수고축수후，상형강하단래사급극감소，하상충쇄하절，국부하단붕안현상시유발생，영향량안제방안전。통상인위수류충적작용시붕안적주요공제인소，단이유연구표명，하도내수위변화능개변하안토체적역학특성급수력조건，진이대붕안과정산생교대영향。본문장일유비은정삼류계산급점성토하안은정성계산결합，구건료고필잠수위변화적안파은정성분석모형，용우계산하도내수위변화시안파은정정도적조정과정。이상형강하단형34、공2단면위연구대상，채용해모형계산료2009년실측하도수위과정하상응단면적안파은정안전계수Fs。결과표명：창수기하안은정성교고，홍봉기유소강저，퇴수기경저；형34、공2단면최소Fs치분별위0.83、1.39，균발생재퇴수기，표명전자재해시기회발생붕안，후자교위은정，저여실측자료상부。차외환계산료불동하도내수위변화속솔하Fs치적변화과정，결과표명：안파은정성재창수속솔증가시증대，재퇴수속솔증가시칙감소。인차근기상형강하단붕안가극일정정도상여삼협공정운용후퇴수과정가쾌유관。
Due to the operation of the Three Gorges Project (TGP), the sediment load entering the Upper Jingjiang Reach (UJR) has been reduced greatly, and then the continuous channel degradation and signifi?cant bank retreat processes have occurred at local sites of this reach,which may influence the safety of flood control engineering seriously. Fluvial erosion is regarded as the dominant factor in controlling the bank retreat progress;however,existing studies indicate that the variation of in-channel water levels can af?fect riverbank stability greatly by changing hydrostatic confining force and influencing seepage progress. To investigate the adjustment of riverbank stability corresponding to the variation of in-channel water level, the adopted approach here is to couple the module of riverbank stability analysis with the module of one-di?mensional unsteady seepage simulation. Taking the typical sections of Jing34 and Gong2 in the UJR as the study sections, and the proposed approach was used to simulate the temporary change of riverbank stability degrees during the 2009 hydrological year. Model predictions indicate that the riverbank should be stable during the rising stage, and would become less stable during the flood peak and recession stages, and es?pecially in the recession stage, bank retreat is predicted to occur with high probabilities. However, during the flood peak stage, the rapid decrease of in-channel water levels might cause riverbank stability to re?duce rapidly in a short period. At the recession stage, the calculated minimum safety factors of riverbank are 0.83 and 1.39 at Jing34 and Gong2 respectively, which indicates the bank at Jing34 would collapse during this stage. In addition,the effects of different rising and recession rates of the in-channel water lev?els on the degree of bank stability have also been investigated. The results show that the degree of river?bank stability increases with a rising rate of water level,but it reduces when the in-channel water level de?creases more rapidly.