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某水电站引水隧洞围岩主要为石英云母片岩,具有显著的蠕变特性。结合该水电站试验洞洞壁位移监测结果,分析了洞室开挖后围岩的时空效应,基于位移反分析法,利用自编神经网络计算程序对幂律型流变模型参数A、n、m进行反演,并将获得的测线位移计算值与实测值相对比,以分析参数的合理性。结果表明,洞壁两侧变形最大,边墙次之,顶拱变形最小;反演得到A为6.687 6×10-17、n为1.967 1、m为-0.918 5,且位移计算值与实测值具有较高的吻合度,表明反演参数合理可靠。最后结合流变参数的反演结果,对该工程调压井开挖后支护时间进行探究,研究发现在洞室开挖15d后进行支护是合理的。
The surrounding rock of the diversion tunnel of a hydropower station is mainly composed of quartz mica schist with obvious creep characteristics. Based on the displacement monitoring results of the tunnel wall of the hydropower station, the space-time effect of the surrounding rock after tunnel excavation is analyzed. Based on the displacement back analysis method, the parameters of the power-law rheological model A, n, m The inversion is performed, and the calculated displacements of measured line are compared with the measured values to analyze the rationality of the parameters. The results show that the deformation of the two sides of the tunnel wall is the largest, and that of the side wall is the second, and that of the top arch is the smallest. The inversion results show that A is 6.687 6 × 10-17, n is 1.967 1, m is -0.918 5, and the calculated displacements and measured values With a high degree of agreement, indicating that the inversion parameters reasonable and reliable. In the end, based on the inversion results of the rheological parameters, the support time of the surge shaft after excavation is explored. It is found that it is reasonable to support the tunnel 15 days after excavation.