Simulation of a Defectless Lifecycle of Unique Underground Structures of the Sewage System at the Stage of Their Construction in Difficult Soil Conditions

Emperor Alexander I Saint-Petersburg State Transport University, Saint-Petersburg, RUSSIA

Simulation of the parameters of a defectless lifecycle of large caissons at the stage of their plunging into heterogeneous soil milieu allows considerable expansion of the area of rational use of underground areas of megacities for deep transport facilities and engineering infrastructure due to provision of structural safety and sustainable operation of a special underground structure. Mega sizes of an RC caisson allow creating open underground areas, unique in volumes and deepness. The analysis of behavior of a massive gravitational fencing caisson at its incrementing and plunging into heterogenenous soil milieu allowed identifying the nature of its non-linear and unsteady behavior. Unsteadiness of the processes of interaction of a large structure and soil milieu accompanied by geometrical changeability causes the necessity to create methods of adaptive control of strain- stress behavior of the system “gravitational large body - heterogeneous host medium” for decreasing aggravating influence of these effects on strength, deformability and reliability of the structure at the subsequent stages of its lifecycle. Due to joint step-by-step implementation of geotechnical and structural calculations a history of the processes of caisson-soil milieu interaction is modeled and the parameters of adaptive control of strain-stress behavior are predicted, thus providing conditions of controlled lowering. The paper demonstrates results of consistent implementation of the given concept at the lifecycle stages of the unique caissons for the sewage system of the megacity beginning from numerical modeling during design to computer models of control of strain-stress behavior of the system “large caisson - soil bulk” using the methods of geotechnology with subsequent monitoring provision of the defectless stage of construction.