Finite element and analytical stochastic models for assessment of underground reinforced concrete water storage facilities and results of their application.

Roman Wróblewski,Janusz Kozubal,Hector Gomez

doi:10.1371/journal.pone.0209916

Roman Wróblewski, Janusz Kozubal + Show 1 more

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https://doi.org/10.1371/journal.pone.0209916

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Abstract

Typical underground water storage facilities consist of reinforced concrete tanks and pipes. Although methods of their analysis are well developed, the use of these methods does not always give unambiguous results, as presented in the paper. An example of underground tank is considered in which cylindrical roof collapsed during construction under soil and excavator loads. The causes of failure are investigated with deterministic and stochastic models. In the first step nonlinear finite element analysis including soil-structure interaction was performed to examine overall level of the structural safety, which was found satisfactory thus not explaining the collapse. In the second step an analytical stochastic model was developed and analysed with emphasis to sensitivity. The last analysis explained the collapse as a complex of unfavourable states for considered variables and the failure was recognised as a mixed construction-geotechnical-structural problem. The key role played backfill properties and its depth.

Highlights

Underground reinforced concrete tanks are commonly used to store rain water
The results are referred to the excavator load multiplier λ as presented in Figs 14–17 for 1⁄2 of the tank buried in the cohessionless soil
According to the obtained results the structure fails as a result of simultaneous yielding of compressed concrete and tensile steel in the shell crown (Fig 17), which occur under the excavator load λult 10–11. This failure mode is different from the observed one

Summary

Introduction

Underground reinforced concrete tanks are commonly used to store rain water. Precast structures of this type can be effective due to a short construction period and almost unlimited volume when build form typical segments. Transport requirements set serious limits– the elements cannot be too large and too heavy. Precast tanks require a number of joints that can be critical points as presented in the paper. Underground structures are loaded with a soil pressure and in the same time interact with the soil. In this way the soil reduces deformation of the structure and influences on a mode of failure. Hard to control and variable soil parameters can play more important role than parameters of the structure

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Results

Conclusion