Abstract:

Halk Mountains are situated in the northern Tianshan range. Their complex geological structure and intense topographic dissection have resulted in well-developed fractures and well-developed fissures within river valleys. This area significantly impacts the overall water resources and ecological environment of the northern Tianshan piedmont. To evaluate groundwater infiltration capacity in this region and explore the permeability characteristics of bedrock fractures in Halk Mountains area, this study proposes a coupled simulation method of discrete fracture-equivalent continuous medium based on the theoretical foundations of discrete fracture network (DFN) model and equivalent continuous medium (ECM) model. Firstly it analyzes the spatial characteristics of regional fissures by integrating the hydrogeological background and natural fissure network characteristics, then performs discrete fissure network simulation according to the natural fissure network characteristics to establish a discrete fissure network model consistent with the regional actual geological conditions, and finally achieves fissure-geological unit coupling based on the equivalent medium model theory to calculate the equivalent permeability of the fissure network. The results indicate that: Fractures in the study area are influenced by Halk Mountain fault structure, with an overall strike predominantly NWW and NEE; The fissure widths follow a log-normal distribution, and the spatial distribution of fissures adheres to a Fisher distribution; The equivalent radius of the fissures ranges from 312.9-780.6 m, the fissure width spans 1.43-25.19 mm, the permeability varies from 2.3-66.7 mD, and the fissure density ranges from 0.10-5.25 m^-1; The equivalent permeability values are 0.050-1.877 mD in the xx direction, 0.050-1.947 mD in the yy direction, and 0.100-2.825 mD in the zz direction, with the permeability of the entire region being less than 3 mD. The bedrock fissure network in Halk Mountains area exhibits relatively low permeability, with fault zones and river valley fissure development zones serving as the primary pathways for groundwater flow in the mountainous region. Comparing the simulation results with previously conducted hydrogeological test results shows good agreement, validating the reliability of the coupled discrete fracture-equivalent continuum simulation method.

Key words: discrete fracture network model')">

discrete fracture network model, equivalent continuous medium model, Halk Mountain')">Halk Mountain, discrete fracture-equivalent continuous medium coupled simulation, hydrogeology