强烈非均质裂隙介质优先流及其工程意义--以HN地下水封洞库为例

Preferential Flow in Strongly Heterogeneous Fractured Media and Its Engineering Significance--A Case Study of HN Underground Water-sealed Cavern

在地下洞库工程建设中,低渗岩体内发育的节理密集带、断层等空隙中通常形成优先流,从而对洞库涌水量与储品水封安全性造成严重影响,因此裂隙介质优先流的识别、工程风险评估以及防渗控制研究具有重要意义。以HN地下水封石油洞库为例,使用FEFLOW地下水模拟工具的非结构化剖分技术对优先流潜在通道进行了精细的几何刻画,建立了工程场区尺度的地下水水流模型,并对施工期中优先流防渗处置不同工况下洞库涌水量与储品水封安全性进行了模拟分析。结果表明:优先流是影响洞库围岩中地下水的流场形态以及洞库涌水量的重要因素,断层、节理密集带等不连续面是主洞室涌水主要的充水途径,优先流形成的涌水量占据主洞室总涌水量的60%以上。在地下工程施工期间做好优先流通道的防渗处理是必不可少的工作。

In the construction of underground works,preferential flow is often formed in densely developed joint zones and faults within low-permeability rock masses,which significantly affects the water influx and sealing safety of the cavern.Therefore,studying the identification of preferential flow,engineering risk assessment,and impermeability control is of great value.In this paper,taking the HN underground water-sealed petroleum cavern as an example,the unstructured meshing technique of FEFLOW groundwater si-mulation tool was used to finely characterize the potential channels of preferential flow,and adverse geolo-gical features such as faults and densely developed joint zones were meshed to establish a groundwater flow model at the engineering site scale.The water inflow and sealing safety under different conditions of prefe-rential flow impermeability control during the construction phase were simulated and compared.The results show that preferential flow is an important factor affecting the flow field morphology of groundwater in the surrounding rock of the cavern and the water inflow.Faults,densely developed joint zones,and other discontinuous surfaces are the main pathways for water filling in the main chamber of the cavern,and the water influx caused by preferential flow accounts for more than 60%of the total water influx.It is essential to carry out impermeability treatment for preferential flow channels during underground engineering construction.