Immersion mode and spatiotemporal distribution characteristic of water migration in loess tunnel

The impact of loess collapsibility on engineering construction has become an important research topic in this field. At present, this kind of research only stays in the static seepage stage, thus ignoring the dynamic seepage mechanism. Therefore, in order to study the seepage mechanism of loess and judge the response of the tunnel in the loess layer to various seepage modes, so as to prevent and treat the tunnel leakage disaster, by studying the existing theories and typical engineering cases, this paper summarizes the two modes of water intrusion in the loess layer, static infiltration and dynamic water infiltration, presenting the law of displacement and deformation of tunnel structure under different modes. The results show that the unsaturated static infiltration model and the dynamic hydraulic infiltration model led to differences in the water distribution and collapse deformation of the stratum; the uneven settlement of the tunnel will cause additional torsional loads on the tunnel structure. However, under the action of dynamic water, the contact load between the lining and the surrounding rock at the water source is 20–24 kPa vertically and 16–95 kPa horizontally, which is greatly affected by the location of the water source; with the downward movement of the water source position, the surface settlement decreases continuously, and the maximum reduction range reaches 50%. Both flooding modes will cause the overall displacement of the tunnel and the obvious settlement of the ground surface, but the related laws of the two modes are not the same. This is a review study that will help build tunnels in the water-rich loess stratum and prevent disasters.