【摘要】 基于R/S分析法与分形理论,对某水电站地下厂房处于同一高层不同剖面的围岩变形特征进了深入剖析,计算了所有多点位移计(4点)测点位移时间序列的Hurst指数与分形维数,提出了围岩开裂的分维判据。研究结果表明,所有测点的位移时间序列的Hurst指数H均在区间(0.5,1)内,且离M410较近剖面的Hurst指数基本趋近于1,这揭示,围岩的变形在今后一段时间仍会继续增长,且增长速率持续提高。当从一个剖面到另一个剖面时,多点位移计的两浅层测点(孔口、5.0m)位移时间序列的分形维数先变小后变大,开裂剖面(M410所处剖面)的分形维数最小,这表明出现维数最小值是该剖面即将发生开裂的前兆与迹象;另外,尽管两深层测点(11.0m、17.5m)总体上存在类似趋势,然而没有如同浅层测点在某个区域存在着显著的单调性这一规律,这表明,M410所处剖面的裂缝深度不可能超出11.0m,其值应该在5.0m到11.0m之间。更多还原

【Abstract】 The deformation characteristic of surrounding rock in the underground powerhouse of a hydropower station is analyzed by R/S method and fractal theory.Hurst indexes and fractal dimensions of displacement time series of all monitoring points are calculated.Fractal dimension criterion is presented.Hurst indexes of displacement-time series of all measurement points are greater than 0.5 and less than 1,and Hurst indexes of displacement-time series in cross-section neighboring from M410 approximate 1,which shows that the deformation of surrounding rock will continue to grow up and its increasing rate keeps accelerating.From one cross-section to another,fractal dimension of displacement-time series collected by multipoint extensometer in two shallower measurement points(orifice、5.0 m) increase and then decrease,and fractal dimension in fractured cross-section where M410 is installed is least,which indicates that the occurrence of dimension minimum is a alarm for the forthcoming cracking of surrounding rock.However,dimension in two deeper measurement-points(11.0 m,17.5 m) do not have the characteristics similar to the one in two shallower measurement-points.It is showed that crack depth in the cross-section where M410 is installed should be greater 5.0 m and less than 11.0 m.更多还原