Application of several non-linear prediction tools for estimating uniaxial compressive strength of granitic rocks and comparison of their performances

2015 ◽  
Vol 32 (2) ◽  
pp. 189-206 ◽  
Author(s):  
Danial Jahed Armaghani ◽  
Edy Tonnizam Mohamad ◽  
Mohsen Hajihassani ◽  
Saffet Yagiz ◽  
Hossein Motaghedi
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Linear Prediction ◽  
Granitic Rocks ◽  
Prediction Tools ◽  
Non Linear

scholarly journals Prediction of Uniaxial Compressive Strength of Granite Rock Samples of Lugoba Quarry Using Rebound Hammer Test

2021 ◽  
Vol 40 (1) ◽  
pp. 16-27
Author(s):  
Moses Kongola ◽  
Karim Baruti
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Granitic Rocks ◽  
Rock Blasting ◽  
Indirect Measure ◽  
Rebound Hammer ◽  
Rock Stability ◽  
Standard Procedures ◽  
Institute Of Technology ◽  
Uniaxial Compressive Strength Test

Rebound hammer test is widely used as an indirect measure of uniaxial compressive strength for engineering materials such as concrete, soil, and rock in both civil and mining engineering works. In quarries, uniaxial compressive strength is a crucial parameter in the analysis of geotechnical problems involving rock stability and rock blasting design. This study aims at establishing the empirical models of uniaxial compressive strength fits on rebound hammer number that can be used to predict uniaxial compressive strength of granitic rock at Lugoba Quarry. Data for direct uniaxial compressive strength were obtained from uniaxial compressive strength test carried out on 20 core samples at the Dar es Salaam Institute of Technology Geotechnical Laboratory using ISMR Standard Procedures. The rebound hammer test was carried out using testing hammer type N. The tests were done horizontally on two scanline's geotechnical domains of the rock mass on the footwall side of the quarry. The obtained results of UCS ranging from 105 to 132.5 MPa and RHN from 44.90 to 49.5 were found to be comparable with values of other granitic rocks in other parts of the world. Regression Analysis using SPSS software was carried out to develop 5 regression models of UCS vs.RHN. The values of obtained in this study were found to be between 0.93 and 0.95, which are comparable with other studies. This implies that RHN accounted between 93 and 95% of the total variation of the UCS and the relationships were very strong. Two models; Logarithmic and exponential were found to be appropriate and recommended for application at Lugoba Quarry.

Constitutive equations for reliable projectile penetration analysis into a concrete medium

2019 ◽  
Vol 11 (2) ◽  
pp. 159-184
Author(s):  
Vladimir R Feldgun ◽  
David Z Yankelevsky
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Equation Of State ◽  
Penetration Depth ◽  
Uniaxial Compressive Strength ◽  
Constitutive Equations ◽  
Concrete Strength ◽  
Time History ◽  
Non Linear ◽  
Concrete Target

This article analyzes the fundamental question of the mechanical properties representation in penetration analysis and its effect on the calculated results. Penetration analysis into a concrete target with a specified uniaxial compressive strength was carried out using different material models appearing in software libraries. These models determine the specific material equation of state and shear strength envelope related to the concrete uniaxial compressive strength. Different results were obtained for the same concrete strength. This proves that the unconfined compressive strength is not the governing parameter which determines the projectile penetration characteristics and that a large variation of results is obtained from different models. Analysis was then carried out on a case with documented constitutive properties of a concrete target that was penetrated by an instrumented projectile. The predicted penetration depth and the projectile deceleration time history were compared with the measured data, and very good correspondence was obtained. This proved that the specific properties of the penetrated medium should be incorporated in the analysis to properly predict the penetration event. The study then examined the commonly used approximation of a linearized equation of state and a linear Mohr–Coulomb model, replacing the true non-linear equations of state and the true non-linear shear strength dependence, and the linearized relationships’ effect on the analyzed results was assessed. A detailed study of the solution sensitivity to different parameters of the Mohr–Coulomb relationship then followed, and its effect on different penetration parameters (nose embedment duration, nose embedment velocity, penetration depth, peak deceleration, quasi-static deceleration) has been examined, to demonstrate how a perturbation in assumed concrete properties affects the solution of the penetration problem. The article illuminates the role of the constitutive equations on penetration analysis and the importance of the proper selection of the representative expressions and of their approximations.

Determination of Concrete Cube Strength from Used Samples / Určení Krychelné Pevnosti Betonu U Použitých Zkušebních Trámců

2012 ◽  
Vol 12 (2) ◽  
pp. 186-194 ◽  
Author(s):  
Oldřich Sucharda ◽  
David Mikolášek ◽  
Jiří Brožovský
Keyword(s):  
Compressive Strength ◽  
Concrete Beams ◽  
Linear Analysis ◽  
Bending Tests ◽  
Cube Strength ◽  
Non Linear ◽  
Compressive Strength Of Concrete ◽  
Concrete Cube

Abstract This paper deals with the determination of compressive strength of concrete. Cubes, cylinders and re-used test beams were tested. The concrete beams were first subjected to three-point or fourpoint bending tests and then used for determination of the compressive strength of concrete. Some concrete beams were reinforced, while others had no reinforcement. Accuracy of the experiments and calculations was verified in a non-linear analysis.

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