Ableitung der thermischen Bodenfunktionen anhand von Körnung und Porengrößenverteilung als Grundlage für In-situ-Vorhersagen des Bodenwärmehaushaltes

In addition to soil structure and pore function disturbances, the impairments of natural soil functions on line construction sites (e. g. power cable routing) also include changes in the site-specific variable thermal-hydraulic properties in the area of the line trenches. Based on the pore size distribution values as a function of dry bulk density classes compiled in German Soil Classification system “KA5” (Ad-Hoc-AG-Boden, 2005), volumetric heat capacity (C), thermal conductivity (λ), and thermal diffusivity (k) can be calculated using the model of Xie et al. (2018). These calculated data are presented for the soil texture spectrum according to KA5, as well for selected textures (Sl3, Lt2, Tu3) and class ranges of dry bulk density (ρ_t).

The typical curves for C (linear increase), λ (increasingly flattening increase) and k (increase with reversal to negative slope) and their rise with increasing ρt (1.1–1.7 g cm⁻³) are shown. k varies depending on the proportions of clay, silt and sand within the soil texture class. The curve shapes between low and high ρt differ more for “Sl3” than for the finer-grained texture class “Tu3”. With the help of these data sets, changes in the heat balance and the thermal- hydraulic soil properties can be predicted for line projects in the power grid expansion before the start of construction measures, if soil texture and dry bulk density are determined by field description methods.