Assessment and Mapping Geological Risk for the Future Subsurface Linear Construction in Moscow

Abstract

Geological risk as the qualitative or quantitative measure of geological hazard or a complex of hazards established for a certain object in the form of possible absolute or relative economic losses (damage) is the function of affecting hazard(s) value and the vulnerability of engineering structure. The georisk analysis in urban areas is usually aimed at the existing urban infrastructure, whereas assessment of geological risk for future construction appears to be a new approach in risk analysis. In urban areas, the risk of probable losses for a particular engineering structure in the course of its construction and operation may be comparatively analyzed for different types of engineering geological conditions distinguished in the area proceeding from the assessment of geological hazards that affect the engineering structures, since the vulnerability of engineering structure to these geological hazards is taken as constant in this case. Upon this approach, the qualitative characteristics of possible damage from geological hazards within the area with engineering geological conditions of a certain type serve as the risk index. According to the developed procedure, the map of geological risk upon the construction and operation of shallow (20 m deep) tunnels was compiled to a scale of 1:100,000 for the territory of Moscow. The possible damage was assessed proceeding from the analysis of such hazards as groundwater and quicksand outburst in the construction pit, suffusion, and karst-suffosion processes affecting the building structures. Very high geological risk arises upon the construction and running tunnels in water-saturated sandy ground, whereas the low risk is identified for the tunnels running in low-permeable Jurassic clay.