Variation Characteristics of Hydraulic Circulation in Groundwater Circulation Well Under Natural Hydraulic Gradient Influence and Method to Expand Applicability

Natural hydraulic gradients in aquifers disrupt the symmetry and closure of circulation systems of groundwater circulation wells (GCW). To address the unsuitability of traditional dual-screen GCWs in establishing hydraulic circulation under high hydraulic gradients, this study proposes enhancing the applicability and remediation efficiency via multi-screen GCWs, and assesses the evolution of hydraulic circulation characteristics as hydraulic gradient changes as well as applicable hydraulic gradient ranges for different screen quantities. Results indicate that the influence of hydraulic gradient on the hydraulic circulation characteristics of GCWs with different screen quantities follows similar trends. Influence radius (R) and circulation efficiency (Pr) exhibit an overall decreasing trend with increasing hydraulic gradient. Offset angle of circulation zone is positively correlated with hydraulic gradient, with downstream offset angle (θD) exceeding upstream offset angle (θU). Triple-screen GCW extends the applicable hydraulic gradient range (0~9.3‰) beyond dual-screen GCW (0~4.3‰), decreases θU and θD by 3.42° and 4.12°, respectively, and increases Pr by 27.62%. Therefore, these findings demonstrate that a multi-screen GCW can effectively expand the applicable hydraulic gradient range and enhance the remediation efficiency of GCWs. This research deepens the understanding of circulation characteristics under the influence of hydraulic gradient and is expected to expand the engineering applicability of GCW technology.