Water Saturation Effects on the Brazilian Tensile Strength of Gypsum and Assessment of Cracking Processes Using High-Speed Video

Wong, Louis Ngai Yuen; Jong, M.

doi:10.1007/s00603-013-0436-1

Cited by 88 publications

(28 citation statements)

References 54 publications

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“…They also found that these saturated rocks suffered from more than 90 % reduction in tensile strength as compared with the dry ones. Water-weakening effect on the Brazilian tensile strength was experimentally investigated by Wong and Jong [77] on gypsum specimens. They observed that the presence of water lowers the tensile strength and has significant effects on the cracking behavior of the gypsum specimens.…”

Section: Other Rock Typesmentioning

confidence: 99%

Water effects on rock strength and stiffness degradation

2015

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Reduction in strength and stiffness in rocks attributed to an increase in water content has been extensively researched on a large variety of rock types over the past decades. Due to the considerable variations of texture and lithology, the extent of water-weakening effect is highly varied among different rock types, spanning from nearly negligible in quartzite to 90 % of uniaxial compressive strength reduction in shale. Readers, however, often face difficulties in comparing the data published in different sources due to the discrepancy of experimental procedures of obtaining the water saturation state and how the raw laboratory data is interpreted. In view of this, the present paper first reviews the terminologies commonly used to quantify the amount of water stored in rocks. The second part of the paper reviews the water-weakening effects on rock strengths, particularly focusing on uniaxial compressive strength and modulus, as well as tensile strength, under quasi-static loading and dynamic loading. The correlation relationships established among various parameters, including porosity, density and fabric of rocks, and external factors such as strain rate, surface tension and dielectric constant of the saturating liquid, absorption percentage and suction pressure, are reviewed and presented toward the end of the paper.

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Section: Other Rock Typesmentioning

confidence: 99%

Water effects on rock strength and stiffness degradation

2015

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“…The tensile strength of a sample dropped to nearly half of its dry value after it was soaked in water for one week, and decreased further only slightly after the specimen was immersed in water for three weeks or ten weeks. Wong & Jong (2014) used a high-speed video system to show that the cracking processes of dry and wet specimens are distinctly different in terms of the speed of crack propagation and the number of cracks that developed. The softening coefficient of Brazilian tensile strength is higher than and linear relative to that of uniaxial compressive strength, and the splitting strengths are nearly the same for dry and saturated rings with an internal diameter of 20 mm (Yilmaz, 2010).…”

Section: Introductionmentioning

confidence: 99%

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

Wang¹

2015

Archives of Mining Sciences

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For coal mine ground control issues, it is necessary to propose a failure criteria accounting for the transversely isotropic behaviors of rocks. Hence, it is very helpful to provide experimental data for the validation of the failure criteria. In this paper, the method for preparing transversely isotropic specimens and the scheme of the Brazilian tensile strength test are presented. Results obtained from Brazilian split tests under dry and water-saturated conditions reflect the effect of the development direction β of the structural plane, such as the bedding fissure, on the tensile strength, ultimate displacement, failure mode, and the whole splitting process. The results show that the tensile strength decreases linearly with increasing β. The softening coefficient of the tensile strength shows a sinusoidal function. The values of the slope and inflection point for the curve vary at the different stages of the Brazilian test. The failure mode of the rock specimen presented in this paper generally coincides with the standard Brazilian splitting failure mode. Based on the test results, the major influencing factors for the Brazilian splitting strength are analyzed and a mathematical model for solving the Brazilian splitting strength is proposed. The findings in this paper would greatly benefit the coal mine ground control studies when the surrounding rocks of interest show severe transversely isotropic behaviors.Keywords: Brazilian split test; Dry and water saturation; Bedding fissure; Strength coefficient; Coal mine ground control W związku z zagadnieniami ochrony powierzchni w kopalniach węgla, konieczne jest opracowanie odpowiednich kryteriów klasyfikacji uszkodzeń skał uwzględniających ich poprzeczną izotropowość. Pomocnym jest także dostarczenie danych eksperymentalnych niezbędnych do walidacji kryteriów uszkodzeń. W pracy tej zaproponowano metodę przygotowywania próbek wykazujących izotropowość poprzeczną, omówiono także sposób przeprowadzania testu na rozciąganie metodą brazylijską. Wyniki testu uzyskane na sucho oraz w warunkach nasycenia próbki wodą wskazują wpływ kierunku rozwoju β płaszczyzny strukturalnej (np. płaszczyzn spękań) na wytrzymałość próbki na rozciąganie, maksymalne przemieszczenia, rodzaj uszkodzenia oraz przebieg procesu pękania. Wyniki testu wskazują, że wytrzymałość na rozciąganie maleje liniowo wraz ze wzrostem wartości β. Współczynnik mięknienia próbki w trakcie próby wytrzymałościowej na rozciąganie ma przebieg krzywej sinusoidalnej. Wartości kąta nachylenia oraz punkt przegięcia krzywej różnią się dla poszczególnych etapów próby wytrzymałościowej. Tryb uszkodzeń próbek skalnych przedstawiony w artykule zasadniczo pozostaje w zgodzie z typowymi odkształceniami rejestrowanymi w trakcie testu metodą brazylijską. W oparciu o wyniki eksperymentu, przeanalizowano główne czynniki wpływające na wytrzymałość próbek na rozciąganie i zaproponowano odpowiedni model matematyczny do obliczania wytrzymałości. Wyniki przedstawione w artykule stanowią poważny przyczynek do badań stabilności gruntu...

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“…The last phase started in 1991 and continues today. It is characterized by the improvement of the original testing method (Wong and Jong, 2013). The same threephase division of Wong and Li is elaborated in this paper (Li and Wong, 2013).…”

Section: Historical Overview Of Development Of Brazilian Testmentioning

confidence: 99%

Current Cognition of Rock Tensile Strength Testing by Brazilian Test

Briševac

Kujundžić

Čajić³

2015

MGPB

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Tensile strength of intact rock materials has been determined by the indirect method more frequently than by the direct method. This paper presents a historical review of the development of the indirect method called the Brazilian test, comprising the period from 1943 to the present day. It stresses some aspects which are essential for interpreting the results of the Brazilian test due to the different degrees of stress during the testing and the direct method of determining tensile strength. The estimate of the direct tensile strength and the influence of sample saturation on the results of indirect tensile strength testing have been specifically elaborated.

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Water Saturation Effects on the Brazilian Tensile Strength of Gypsum and Assessment of Cracking Processes Using High-Speed Video

Cited by 88 publications

References 54 publications

Water effects on rock strength and stiffness degradation

Water effects on rock strength and stiffness degradation

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

Current Cognition of Rock Tensile Strength Testing by Brazilian Test

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