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1

Experimental study of compressive failure of concrete under static and dynamic loads

Liu L., An H. M.

Archives of Civil Engineering

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2020

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Vol. 66, nr 3

427--441

EN

The fracture and fragmentation of concrete under static and dynamic loads are studied. The uniaxial compressive strength test is employed to study the concrete behavior under static loads while the split Hopkinson pressure bar is used to study the dynamic behavior of the concrete under static loads. The theories for acquiring the stress, strain and strain rate of the concrete in the dynamic test by Hopkinson pressure bar has been introduced. The fracture patterns of the concrete in the uniaxial compressive test have been obtained and the static concrete compressive strengths have been calculated. The fracture patterns of the concrete in the uniaxial compressive test have been obtained and the static concrete compressive strengths have been calculated. The fracture and fragmentation of the specimen under dynamic loads have been acquired and the stress-strain curves of concrete under various impact loads are obtained. The stress-strain curve indicates a typical brittle material failure process which includes existing micro-fracture closure stage, linear-elastic stage, nonlinear-elastic stage, and post-failure stages. The influence of the loading rate for the compressive strength of the concrete has compared. Compared with the concrete under static loads, the dynamic loads can produce more fractures and fragments. The concrete strength is influenced by the strain rate and the strength increases almost linearly with the increase of the strain rate.

2

Particle Flow Code modeling of the mechanical behavior of layered rock under uniaxial compression

Yao Nan, Ye Yi-Cheng, Hu Bin, Wang Wei-Qi, Wang Qi-Hu

Archives of Mining Sciences

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2019

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Vol. 64, no. 1

181--196

EN

In this paper, the different mechanical behaviors of layered rocks with different bedding angles during uniaxial compression tests are studied. Numerical simulation models of layered rock are validated based on laboratory tests, and uniaxial compression tests are conducted by using Particle Flow Code (PFC). Using these simulations, the uniaxial compressive strength, failure patterns, development of micro-cracks, and displacement of meso particles are analyzed. When the bedding angle is similar to the failure angle, the macro failure planes develop directly along the beddings, the bedding behavior dictates the behavior of the layered rock, reducing the compressive strength.

PL

W pracy badano właściwości mechaniczne skał warstwowych zalegających pod różnym kątem uwarstwienia w warunkach ściskania jednoosiowego. Walidację modeli symulacyjnych skał warstwowych przeprowadzono w oparciu o wyniki badań laboratoryjnych, zaś testy ściskania jednoosiowego prowadzono z użyciem pakietu Particle Flow Code (PFC). W oparciu o badania symulacyjne, analizowano wytrzy-małość skał na ściskanie jednoosiowe, modele pękania, powstawanie mikropęknięć i przemieszczenia mezo- cząstek. W przypadku gdy kąt płaszczyzny uwarstwienia ma wartość przybliżoną do kąta pęknięcia, płaszczyzny pękania w skali makro pojawiają się wzdłuż spękań, a układ warstw skalnych determinuje ich wytrzymałość na ściskanie, powodując jej obniżenie.

3

Zmiany wytrzymałości w warunkach krystalizacji soli oraz oddziaływania dwutlenku siarki w wybranych makroporowatych skałach węglanowych

Bobrowska A.

Przegląd Geologiczny

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2013

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Vol. 61, nr 5

311--314

EN

The article presents the changes in long-term endurance of macroporous carbonate rocks by modelling the process of crystallization of salt (sodium sulphate) from the solution and the impact of sulphur dioxide in the presence of humidity. The characteristics of travertine endurance were determined based on the uniaxial compression test of endurance. Tests were conducted in laboratory conditions on monoliths from Poland and Turkey. Rock material from Poland was the so-called "Polish travertine" collected from an active quarry in Raciszyn (RA) and represented by Upper Jurassic limestones. The material from Turkey was a reed-type travertine rock, one of the leading lithotypes from the Denizli region, taken from an active quarry in Hierapolis (HO), and weathered material collected from the ancient opening in Hierapolis (HA). Research shows that the rock materials, regardless of the degree of weathering and location, have an increased susceptibility to lower endurance to uniaxial compression as a result of the impact of SO2 in the presence of humidity, rather than as a result of the crystallization of salt from the solution. This observation demonstrates that the travertine is characterised by relatively high resistance to salt solutions. Within porous material, the salt crystals can freely crystallize in the gaps without damaging the structure.