Strength of hard foundation rocks in the Southern Yakutian permafrost region (city of Neryungri)

Abstract

This paper discusses the results of a statistical analysis of data from geotechnical surveys conducted in the mid-1970s in the city of Neryungri, southern Yakutia, located on sporadic, warm permafrost. The analysis included 162 laboratory determinations of uniaxial compressive strength of sandstone specimens. The test specimens were taken from core obtained boreholes. The study of the probabilistic distributions of sandstone strength values in the total sample population and in the formal groups divided into the rock strength categories has shown the following. In an unfavorable (artificially water-saturated) and favorable (frozen or air-dry) natural state, the Jurassic sandstone in the vast majority of cases is, according to the, a reliable and stable rock foundation for engineering structures. The range of average values for the rock varieties: sandstone of low strength and moderate strength together with sandstone of high strength in water-saturated and natural condition is 8.83–92.81 and 30.91–127.00 MPa. Comparison with the average dry strength values reported by Russian and foreign authors has shown that the Neryungri sandstone differs little in strength from sandstones southern Yakutia permafrost region (87.26 MPa), but also the territory of the former RSFSR, now Russia (84.53 MPa). On a regional scale, the proximity of a common measure of average strength and common territorial belonging, one of the sides of the natural essence of sandstone appears as a representative of the class of sedimentary rocks of the Eurasian continent.