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论述了考虑开挖卸荷效应的二维位移反分析方法。对龙滩水电站左岸岩质边坡1-1剖面进行地质概化、施工开挖分区和开挖扰动分区,建立有限元计算模型。根据试验和现场实测资料,确定待反演得参数和取值范围,通过二维弹塑性有限元方法与神经网络-遗传算法相结合反分析出岩体力学参数。基于该参数的正分析计算结果表明,计算位移与监测位移趋势一致,量值吻合。开挖面附近最大压应力约为1.0MPa左右,开挖面附近基本上没有拉应力区。开挖完成后的塑性区主要分布在坡顶和开挖面及大断层附近,而且基本上发生在开挖损伤区和部分卸荷影响区。
The two-dimensional displacement back analysis method considering the effect of excavation unloading is discussed. Geological generalization, excavation zoning and excavation zoning are carried out on section 1-1 of the left bank rock slope of Longtan Hydropower Station, and a finite element calculation model is established. According to the experimental data and field measurements, the parameters and the range of values to be inverted are determined, and the mechanical parameters of rock mass are inversely analyzed through the two-dimensional elasto-plastic finite element method and the neural network-genetic algorithm. The positive analysis and calculation based on this parameter shows that the calculated displacements are consistent with the trend of monitoring displacements. The maximum compressive stress around the excavated surface is about 1.0MPa, and there is almost no tensile stress zone near the excavation surface. The plastic zone after excavation is mainly distributed on the top of the slope and the excavation face and near the large fault, and basically occurs in the excavation damage area and part of the impact area of unloading.