Study of degradation patterns of strength properties in soil massif due to dynamic (explosive) loading

Purpose. Establishing the patterns of changes in physical and mechanical properties of loess loams of the Dnipro region under the influence of explosive loading in conditions of a technogenically altered geological environment for assessment of stability and prediction of soil behavior during further engineering development of the territories. Methods. A series of laboratory experiments is conducted on samples of loess loams collected from the right-bank part of the city of Dnipro, specifically from an area damaged by an explosion. The samples are analyzed for their physical parameters (density, moisture content, porosity), as well as for their granulometric and chemical composition. Tests are carried out using the TriSCAN (VJTech) software to determine strength parameters before and after explosive loading. Thixotropic changes in the soils are also analyzed over a period of 35 days following the explosion. Results. The patterns of strength changes in the zone compacted by the explosion are established, with a 2–2.5-fold increase in specific cohesion observed in the area of maximum impact. This increase gradually decreased to natural values at a distance of 13–14 meters, and then dropped below the initial level. Over the course of 6–7 days following the explosion, cohesion increased by 25–30%, confirming the manifestation of thixotropy. The internal friction angle changed during the first 5–7 days, after which it stabilized. Scientific novelty. For the first time, changes in physical and mechanical characteristics of loess loams of the Dnipro region due to degradation under explosive loading have been experimentally established. The dependency of cohesion and internal friction angle changes on time after loading is determined, which makes it possible to justify the mechanism of massif degradation under technogenic impact conditions. Practical significance. The obtained experimental results can be used in the design, construction, and operation of engineering structures in areas affected by explosive loading. Taking into account the changes in physical and mechanical properties of the soil massif allows improving safety and durability of construction projects, particularly on specific loess soils.