地下厂房围岩位移混沌动力学特征研究

STUDY ON CHAOS DYNAMIC FEATURE OF SURROUNDING ROCK DISPLACEMENT OF UNDERGROUND POWERHOUSE

以小湾水电站地下厂房围岩不同监测断面的多点监测位移为例,运用功率谱分析方法,改进G-P方法提取关联维数D,综合分析G-P法、C-C法和复自相关法得到合适的m,τ值重构相空间,计算最大Lyapunov指数,研究地下厂房围岩位移的混沌动力学特征。研究表明,主厂房围岩顶拱部位的多点位移和拱座在30m深度处的位移不具有混沌特性,而拱座在2,7和15m深度的监测位移和边墙部位的多点位移,各施工支洞和排水洞获得的超前监测多点位移都具有混沌动力学特征,同时得到表征其混沌动力学特征的功率谱图,关联维数D大于0,最大Lyapunov指数大于0。对具有混沌特性的监测位移,可以利用基于混沌时间序列的多种方法对位移进行预报,为地下厂房系统围岩位移预报提供新的实用方法。

Taking the multi-point displacement data of the main powerhouse surrounding rock as example, through multi-point measuring displacement data from different sections of surrounding rocks in underground powerhouse ofXiaowan Hydropower Station, the chaos dynamic features of displacement data of underground powerhouse are studied by applying the power spectrum analysis method, and G-P method is improved to gain correlation dimension D; then the maximum Lyapunov exponent（21） is calculated by reconstruction phase space with adaptable parameters m, l that are obtained through synthetic analyzing G-P method, C-C method and multiple autocorrelation method. Results show that all the measuring multi-point displacement data in roof and of depth 30 m in abutment don＇t have chaos dynamic feature, but data from depth 2, 7, 15 m in abutment, the wall and those pre-measuring multi-point displacement data gained from constructing branch and drainage caves have chaos dynamic feature. The power spectrum graph has been gained to reflect chaos dynamic feature of displacement data. Correlation dimension D and the maximum Lyapunov exponents are greater than zero. For the displacement data, which have chaos characteristics, many methods can be used during excavation on the basis of the chaotic time series, which can provide a new practical method to forecast the surrounding rock displacement of underground powerhouse system.