Impact of varying properties of geological environment on the formation of loads at shallow-laying underground structures

Purpose. Investigation of the influence of changes in the combination of porosity and soil moisture on the formation of loads and current forces in shallow underground structures. The mechanism for formation of loads at shallow–laying underground structures is considered; the impact of soil humidity factor on the formation of loads at an underground structure, the value and distribution of effective load and the formation of the bending moments in structures are reasoned. Methodology. A data set for the geological environment of right bank Kyiv was gathered for investigation of the issue, including data from 362 boreholes and 512 geological elements, with the sampling depths of up to 60 m beneath the ground level. The surface plots were obtained for dependencies concerning the specific adhesion and ground deformation module to the combined fluidity indicator and porosity coefficient for loam, sandy loam, and clay. The nature of decrease in soil strength indicators (deformation module and specific fluidity) under increasing humidity is shown. The modeling of displacement distribution for soils with different humidity around a shallow–laying tunnel, as well as the formation of loads on the tunnel casing was performed. The dependencies between the bending moments at the tunnel’s arch peak and the change in fluidity value in different types of soils were built. Originality. It consists in the development of ideas about the mechanism of load formation on underground structures of shallow foundation in a changing geological environment. The recommendations were given for considering the potential increase in effective stress in underground structures, depending on the combination of porosity and humidity of soils. Practical implications. Dependences of specific adhesion and modulus of soil deformation on the combination of flow index and porosity coefficient for sands, loams and clays are obtained. Recommendations are given to take into account the possible increase in the existing forces in underground structures depending on the combination of porosity and soil moisture.