基于增量分析的堆石坝瞬变-流变参数联合反演

Joint inversion method of instantaneous and creep parameters of rockfill dam based on incremental analysis

结合南欧江7级面板坝的原型监测资料,提出了基于增量分析的堆石坝瞬变-流变参数联合反演方法。利用停工期或相对停工期堆石体的变形,对流变与瞬变本构模型参数的解耦,在免疫遗传算法的基础上反演了堆石的增量流变模型和E-B模型参数,并分析了当前广泛使用的水管式沉降仪测量结果可靠性和反演分析的精度。结果表明:(1)依据现行规范得到的堆石料室内试验结果,高估了现场填筑体的力学参数,计算沉降比大坝实际值减小了28%;(2)由于埋设时间滞后于大坝填筑过程以及土拱效应的存在,使得水管式沉降仪的实测沉降量比大坝实际沉降量减小45%,水管式沉降仪的实测变形不能直接应用于反演分析;(3)根据现场仪器埋设情况,建立了漏测量与沟槽内外土压力比的函数关系式,可修正水管式沉降仪测值;(4)分时段的增量反演方法可避免水管式沉降仪测量过程存在的"漏测与少测"等系统误差,得到计算值与实际变形吻合较好,更适用于土石坝力学参数反演分析。

Based on the original monitoring data of Nanoujiang VII grade CFRD,a joint inversion method of transient-rheological parameters for rockfill dam based on the incremental analysis was proposed.The parameters of the incremental rheological model and E-B model of rockfill were inversed using the immune genetic algorithm.The reliability of the measurement results and the accuracy of the inversion analysis of hydraulic overflow settlement gauge were studied.The results show that:(1)The laboratory test parameters of the rockfill materials obtained according to the current norms are much higher than the parameters of the practical field filling body,and the calculated settlement is 28%less than the measured value of the dam.(2)Due to the fact that the embedding time lags behind the actual filling process of the dam and the existence of the soil arching effect,the measured settlement from the hydraulic overflow settlement gauge is 45%less than the actual settlement of the dam.The measured deformation cannot be directly used for the inversion analysis.(3)According to the embedded condition of the field monitoring instruments,the function relation between the leakage measurement and the ratio of inside soil pressure to outside soil pressure of the trench is established,which can be used to correct the measured value of the hydraulic overflow settlement gauge.(4)The incremental inversion method in different periods can avoid the miss and less measurement value in the measurement process of the hydraulic overflow settlement gauge.The calculated value is in good agreement with the actual deformation,and therefore it is more suitable for the back analysis of mechanical parameters of earth-rockfill dams.