Diagnostic and Analysis of Specific Soil with Ground Water Level and Plain Concrete Slab Interaction

摘要

This article deals with the selected task soil and structure interactionin case of a thin concrete slab and increased groundwater level. Thesoil and structure interaction is a complex task applied in caseswhen necessary to sufficiently consider the proposal's safety andeconomy. The particular topic dealt with is the performed specificexperiment of a concrete slab on the subsoil that is subsequentlysimulated using 3D computing models. The performed experimentis a concrete slab with dimensions 2000 x 2000 mm. The concreteslab thickness was 150 mm. Computing models are based on theFinite Element Method and non-linear analyses. The specificity ofthe experiment is that it simulates extreme foundation conditionswhen the groundwater level almost reaches the foundation base.The experiment confirmed the significant effect of the groundwaterlevel, the reduction of the overall bearing capacity of the slab andthe rapid disturbance and collapse of the slab. Numerical modelsalso described very well the occurrence of cracks and slab collapse.The results were in good agreement with the experimental testing.Major specificities include that the measuring and load test recordsare supplemented with an acoustic emission to identify concretecracks. Findings from acoustic emission make it possible todescribe the formation of cracks at a time when cracks are notvisible and to verify the subsequent behaviour of the slab. Theresearch task presented also includes detail laboratory tests of theconcrete used. Laboratory tests include tests of compressivestrength, modulus of elasticity and tensile strength. Tensile strengthwas determined based on splitting tensile strength and bendingtensile strength tests. In the case of bending tensile strength, testvariants were performed, which differed in the test configuration(three-point bending test, four-point bending test), the size of thetest specimens and the notch in the middle of their span. Numericalmodelling of the slab's interaction with the subsoil is also precededby modelling a small structural element, a beam with reinforcement.Numerical modelling itself is also based on the use of the conceptidentification of fracture mechanics parameters by laboratory tests.