Application of sprayed concrete is very common for supporting geotechnical and underground
structures. The fundamental difference between sprayed and cast concrete is that shotcrete has to support
its own weight immediately after being placed even on overhanging surfaces, therefore its initial and
early strength development are crucial for the stability of structure as well as the safety of personnel.
Sprayed concrete has to provide sufficient support pressure at these early ages to allow fast continuation
of works. In structural design on the other hand, properties of hardened concrete i.e. final reached values
govern the behaviour of structure.
Thesis deals with the advanced constitutive models for sprayed concrete with incorporated time
dependence of strength and stiffness parameters. Some of the analysed models account also for the postpeak
behaviour in both compression and tension. The main goal of the presented thesis is to explore
advantages and disadvantages of the advanced non-linear constitutive models in comparison to the
simple linear-elastic and bilinear elasto-plastic models currently used in the industry.
Descriptions of constitutive models implemented in the most commonly used commercial software in
the industry such as Abaqus, ZSoil and Plaxis are provided in the first part of the thesis. The biggest
disadvantage of presented advanced models is the abundance of required input parameters. Some of
them cannot be obtained from simple laboratory or in-situ tests. For this reason, experience based or
recommended values by the software developer are mainly used. Nevertheless, the most reliable
parameters can be only obtained by the back calculation of the pre-construction testing of sprayed
concrete samples. To conduct the back calculation analysis, the results of uniaxial compressive strength
at different ages and the results of energy absorption tests were obtained from foreign laboratories. Back
calculations of these tests were performed to determine or confirm the commonly used input parameters
for advanced sprayed concrete models. Further on, the practical implication of advanced constitutive
models is presented on a case history from the Tabor tunnel, located at the Razdrto – Nova Gorica
motorway in Slovenia. Main findings of the performed research and discussion on the advantages and
disadvantages of use of advanced material models for sprayed concrete in the tunnelling industry
conclude the presented thesis.
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