Field and numerical investigation of soil hydro-thermal response to the climatic conditions in southern China considering soil heterogeneity

It is essential to investigate soil hydro-thermal behavior to reduce the potential damage to geotechnical constructions caused by varying climatic conditions. In this work, an in-situ monitoring station was built on a clay slope with high groundwater table, situated in Yixing, China. Ten SMT-100 sensors were instrumented on the site to record the evolutions of soil temperature and volumetric water content at various depths. Meteorological information, including relative humidity, air temperature, rainfall, wind speed and solar radiation, and slope runoff was collected. A numerical investigation was also conducted to analyze the variations of soil hydrothermal response to the recorded climatic conditions by combing coupled hydro-thermal model and soilatmosphere interaction model. The profiles of soil temperature and volumetric water content suggest that the diurnal changes are limited to depths <40 cm, and the seasonal changes are usually approaching a location deeper than 120 cm. Soil heterogeneity can affect its hydro-thermal response, e.g., higher volumetric water content was observed at the points with lower dry density, which is mainly related to soil water retention capacity. However, appropriate theoretical models to consider soil heterogeneity in the description of soil hydrothermal properties need to be further investigated.