基于Pilot Point方法反演裂隙岩体参数化渗透结构

Inverse Modeling of Parameterized Hydraulic Conductivity Field in a Fractured Medium Based on Pilot Point Method

在裂隙岩体地下工程中,渗透性能是工程场地水文地质条件最为关注的关键因素之一,对工程场地最终安全性能评价起着至关重要的作用.以我国沿海某核设施花岗岩场地为研究对象,采用Pilot Point调参方法、PEST并行反演程序及3D克里金插值方式,表征裂隙岩体的渗透空间结构.研究表明:该方法可较好地拟合稳定条件下钻孔水位,验证地下水位动态演化趋势;建立的参数化渗透结构模型在实测数据分布的区域反演结果更为精细,模型参数的综合灵敏度程度受观测水位的位置、数量及变程等影响.Pilot Point方法一定程度上可以识别裂隙介质渗透结构的空间差异性,有助于进一步提升裂隙介质渗流模拟预测能力.

For the underground engineering site in a fractured rock mass,the hydraulic conductivity is a critical factor influencing hydrogeological conditions and plays a pivotal role in the final assessment of site performance.This study focuses on the granite formation of nuclear facility site in the coastal area,China.It applied the Pilot Point calibration technique in conjunction with a 3D kriging interpolation method to establish a parameterized hydraulic conductivity field for the fractured medium.Besides,the inverse parameter estimation tool PEST for automated calibration and sensitivity analysis was employed.The results indicate that the simulated hydraulic heads were in a good agreement with the measured data in the steady condition,and well reproduced dynamic behavior of groundwater level with time.Notably,the hydraulic conductivity filed could be estimated more accurately around the boreholes and the parameter sensitivity was related with borehole location,borehole quantity and variogram range.Based on these findings,it could conclude that Pilot Point method could identify spatial difference of hydraulic conductivity filed in the fractured rocks.It is positive to further improve the groundwater flow prediction ability in the fracture medium.