基于区域化变量理论的坝基渗流数值方法研究

Research on the numerical simulation method of seepage analysis of the base of dam based on regionalized variable theory

坝基岩体渗透系数分布具有强烈的空间变异性,其试验数值差别可达几个数量级,可用区域化变量加以描述。本文基于向家坝水电站坝基渗透性的丰富试验成果,研究了基于区域化变化理论的渗透系数空间分布描述的克里金插值法,并应用在渗流数值计算中。以向家坝典型坝段渗流数值计算为例,分别采用按高程统计方法和克里金插值法对数值模型渗透性进行描述,并得到了渗流场空间分布及测点渗压变化过程。测点渗压实测值与计算值变化规律相同,数值相近。计算单元渗透系数赋值方法不同,坝基渗流场的空间分布也不相同。由于克里金插值方法真实地反映了坝基渗透性空间分布,故渗流数值计算成果更真实;数值计算时渗透系数描述采用克里金插值方法是一种有效、方便且可靠的方法。

Spatial variation is one of the remarkable characteristics of the coefficient of permeability of rock mass in the dam base.The difference of permeability of rock mass at the same site could reach several orders.Based on the abundant permeability results obtained by site test method in Xiangjiaba hydro-power station,Kriging interpolation method was studied for the description of spatial distribution of coefficient of permeability and was applied in the seepage numerical simulation.Statistical method according to elevation of dam base and the Kriging interpolation method were both used in the numerical simulation of a typical dam section of Xi-angjiaba hydro-power station to analyze the difference of the different simulation method.It indicates that the variation law of both the calculated and measured pore pressure in the rock mass is same,and the magnitude of the calculated and measured pore pressure is also closed to each other.It also shows it is different of the spatial distribution of seepage field if the coefficient of permeability of the element is given by different method.Because the Kriging interpolation method reflects the reality of spatial distribution of the coefficient permeability,the seepage numerical simulation results will be more reality than the results obtained by other method.Therefore,the Kriging interpolation method is effective,convenient and reliable way for the description of coefficient of permeability in the numerical simulation.