Experimental Determination of the Mechanical Properties and Deformation Constants of Mórágy Granitic Rock Formation (Hungary)

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 (m), the strength of rock (r c) and the ratio of Young's modulus to the strength of rock known as modulus ratio (M R), 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 (M R = E/r c) of 50 granitic rock samples collected from Bátaapáti radioactive waste repository were examined. Fifty high-precision uniaxial compressive tests were conducted on strong (r c-[ 100 MPa) rock samples, exhibiting the wide range of elastic modulus (E = 57.425-88.937 GPa), uniaxial compressive strength (r c-= 133.34-213.04 MPa) and Poisson's ratio (m = 0.18-0.32). The observed value (M R = 326-597) and mean value of M R = 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 M R and other mechanical parameters such as maximum axial strain (e a, 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. Keywords Uniaxial compressive test Á Modulus of elasticity (E) Á Modulus of rigidity (G) Á Bulk modulus (K) Á Modulus ratio (M R) Á Maximum axial strain (e a, max) Á Mórágy granite formation Á Mathematical model 1 Introduction Rock engineering properties are considered to be the most important parameters in the design of ground works. Two important mechanical parameters, uniaxial compressive strength (r c) and elastic modulus of rock (E) should be estimated correctly. There are different empirical relations between r c and

Influence of Parallel Joint Spacing and Rock Size on Rock Bulk Modulus

“…e values of the parameters d, f, and g in Table 7 are listed in Table 8 according to (5). Furthermore, the values from Table 8 were used to draw the fitting curves of the rock size (d, f, and g are drawn), as shown in Figure 6.…”

“…e value of CSBM was substituted into (5), and the characteristic bulk modulus (CBM) of rocks with different PJS values is described in Table 10. l=100 mm discrete point l=200 mm discrete point l=400 mm discrete point l=600 mm discrete point l=800 mm discrete point l=1000 mm discrete point l=1200 mm discrete point l=100 mm curve fitting l=200 mm curve fitting l=400 mm curve fitting l=600 mm curve fitting l=800 mm curve fitting l=1000 mm curve fitting l=1200 mm curve fitting Figure 8 shows that the CBM increases gradually with the increase of the PJS, thereby exhibiting a linear relationship.…”

“…It can be therefore concluded that the numerical simulation and experimental conclusions were consistent. Moreover, the evaluation analysis indicates that the mathematical model, proposed in (5), is applicable for the solution of the bulk modulus with respect to the size.…”

“…For instance, Blake and Faulkner [4] have conducted seepage tests on granite to examine the e ect of bulk modulus on fracturing permeability. Furthermore, Davarpanah et al [5] studied the relationship between the modulus ratio and bulk modulus. Liu and Zhang [6] conducted an indoor triaxial creep test and found that the absolute value of the bulk modulus decreases with an increase in creep stress.…”

Characterization of Hoek–Brown constant mi of quasi-isotropic intact rock using rigidity index approach

“…Although several practical, empirical, and probabilistic approaches have been presented in the literature to address uniaxial compressive strength (UCS) [12,34,36,73,80], the accurate determination of m i is still challenging task and is influenced by many factors such as mineral composition, grain size, and cementation of rock. Generally, m i presents curve-fitting parameter for Hoek-Brown failure envelope [37].…”