Dynamics of the physical properties of sandstone within the depth of annual ground temperature variation, Southern Yakutia (Neryungri case study)

Using available geotechnical laboratory testing data for residential district M in the city of Neryungri, this study presents the first generalized probabilistic estimates of the variation in physico-mechanical properties of the sandstone mass within the depth of annual temperature variation. Although the individual values of bulk density, dry strength and softening coefficient vary randomly within the sampling depth range of 1–18 m, the mean interval estimates systematically increase with depth, forming a zonal system of three boundaries. Occurring at the first boundary at a depth of 2,0 m is weathered sandstone with a blocky structure. The second boundary is at 6,0–7,0 m depth where the sandstone mass is strongly fissured and has a seamy structure. The third boundary is at 10–15 m with very strong sandstone of massive structure. The upper part of the zonal system with an average bulk density of 2,53 g/cm3 is characterized by the greatest average strength loss (47 %) from initial strength of 70,2 MPa. The lower part with bulk densities of 2,58–2,61 g/cm3 and strengths of 110,00–115,30 MPa exhibits minimal strength loss, 22 %. Overall, the sandstone mass can serve as competent foundation for engineering structures provided that its air-dry condition is maintained.