Study on the regularity of rainfall infiltration and deformation in ground fissure zones of loess in Xi’an City under the background of rising groundwater level

This study aims to investigate the deformation patterns of loess ground fissure sites in Xi’an under the combined effects of rising groundwater levels and rainwater infiltration. Based on the characterization of ground fissure disasters, groundwater levels, and rainfall, and supported by laboratory geotechnical tests, the physical-mechanical properties and collapsibility characteristics of the loess in fissured zones were studied. Moreover, finite difference numerical simulations were employed to analyze the deformation behavior induced by rainwater infiltration under the influence of groundwater level rise at the loess fissure sites of Xi’an. The results indicate that the loess in these fissured sites exhibits strong collapsibility and low tensile strength. Under rainfall infiltration alone, the loess fissure zones exhibit “cantilever beam” type deformation, with with displacements on the order of millimeters. Under the combined effects of rising groundwater levels and rainfall infiltration, deformation magnitues can reach several centimeters, predominantly resulting in tensile failure, with the upper layer demonstrating higher tensile strength than the lower layer. These findings suggest that the synergistic interaction of groundwater level rise and rainwater infiltration produces a amplification effect, and increases the risk of tensile failure in loess ground fissure areas.