Experimental Determination of the Mechanical Properties and Deformation Constants of M\xf3r\xe1gy Granitic Rock Formation (Hungary)

M Davarpanah,B Vásárhelyi,G Somodi,L Kovács

doi:10.1007/s10706-020-01218-4

M Davarpanah, B Vásárhelyi + Show 2 more

Open Access

https://doi.org/10.1007/s10706-020-01218-4

Copy DOI

Abstract

Determination of the mechanical behaviour of intact rock is one of the most important parts of any engineering projects in the field of rock mechanics. The most important mechanical parameters required to understand the quality of intact rock are Young’s modulus (E), Poisson’s ratio (ν), the strength of rock (σc) and the ratio of Young’s modulus to the strength of rock known as modulus ratio (MR), which can be used for calculations. The particular interest of this paper is to investigate the relationship between these parameters for Hungarian granitic rock samples. To fulfil this aim, Modulus of elasticity (E), Modulus of rigidity (G), Bulk modulus (K) and the modulus ratio (MR = E/σc) of 50 granitic rock samples collected from Bátaapáti radioactive waste repository were examined. Fifty high-precision uniaxial compressive tests were conducted on strong (σc > 100 MPa) rock samples, exhibiting the wide range of elastic modulus (E = 57.425–88.937 GPa), uniaxial compressive strength (σc = 133.34–213.04 MPa) and Poisson’s ratio (ν = 0.18–0.32). The observed value (MR = 326–597) and mean value of MR = 439.4 are compared with the results of similar previous researches. Moreover, the statistical analysis for all studied rocks was performed and the relationship between MR and other mechanical parameters such as maximum axial strain (εa, max) for studied rock samples was discussed. Finally, the validity of the proposed mathematical model by Palchik (Geomech Geophys Geo-energy Geo-resour 6:1–12, 2019) for stress–strain behaviour of granitic rock samples was investigated.

Highlights

Rock engineering properties are considered to be the most important parameters in the design of ground works
Strength and modulus together will give a realistic understanding of the rock response to engineering usage. This approaching of defining the quality of intact rocks was proposed by Deere and Miller (1966) considering the modulus ratio (MR), which is defined as the ratio of tangent modulus of intact rock (E) at 50% of failure strength to its compressive strength
The mean value of (MR mean = 439) for all granitic rock samples observed in this study and the mean value of (MR mean = 420) obtained by Deere (1968) for limestone and dolomite and the mean value of (MR mean = 380.5) obtained by Palchik (2011) for carbonate rock samples are similar

Summary

Introduction

Rock engineering properties are considered to be the most important parameters in the design of ground works. Curves OA, OB and OC represent three stress–strain curves with failure occurring at A, B and C, respectively According to their sample, curves OA and OB have the same modulus but different strengths and strains at failure, whereas the curves OA and OC have the same strength but different modulus and strains at failure. Strength and modulus together will give a realistic understanding of the rock response to engineering usage This approaching of defining the quality of intact rocks was proposed by Deere and Miller (1966) considering the modulus ratio (MR), which is defined as the ratio of tangent modulus of intact rock (E) at 50% of failure strength to its compressive strength (rc)

Objectives

Findings

Discussion

Conclusion