Modeling of temperature fields under the support of a railway bridge in the cryolithozone

The paper presents a mathematical model for simulating the dynamics of temperature field changes in the soil surrounding the emergency support structure of a railway bridge located in the permafrost zone. The support structure, consisting of 12 large-diameter concrete piles connected by a concrete grillage, experienced significant subsidence of 15 mm over a 6-month observation period. The bearing capacity of the pile foundation is highly dependent on the soil temperature regime, which is influenced by multiple factors such as global warming, solar radiation with account taken of the North-South orientation of the support structure, soil lithology, temperature-dependent thermophysical properties, and local climatic conditions. To model the non-stationary temperature fields, a finite-difference method was employed. The proposed approach introduces two key innovations: the first is the integration of temperature-monitoring data into a numerical method to determine climate-warming trends specific to the geographic location, and the second is the consideration of the historical soil temperature regime around the pile foundation since the bridge construction and commissioning in the Yamalo-Nenetz Autonomous District. The method is validated through numerical simulations, which analyze seasonal temperature field variations at different depths. The results provide insights into characteristic temperature distributions in the soil, taking into account the support orientation.