Evaluation of the deformation modulus of rock masses using RMR

Galera, M; Álvarez, Marino Pérez; Bieniawski, Z.T.; Jose, Jose

doi:10.1201/noe0415450287.ch9

Cited by 20 publications

(18 citation statements)

References 2 publications

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“…Until this point, several researchers in rock mechanics and rock engineering have studied the relation between the unconfined compressive strength ratio σ cm / σ c and the deformation modulus ratio E rm /E r and found that these can be related approximately by the following equation (Ramamurthy [38]; Singh et al [40]; Singh and Rao [41], Galera et al [17]):…”

Section: Q Based Methodsmentioning

confidence: 99%

“…(17) i.e. This equation corresponds to another suggestion of Galera et al [17], which is based on pure empirical calculation. According to Eq.…”

Section: Normalized Equationsmentioning

confidence: 99%

“…In case of poorer rock masses, i.e. RMR < 50 %, they proposed the following form [17]: Some researchers suggest that there is an exponential correlation between the deformation modulus of rock mass and the RMR/GSI values:…”

Section: Independent Equationsmentioning

confidence: 99%

“…According to Galera et al [17], there is an expression involving both rock mass modulus (E m ) and rock mass strength (σ rm ):…”

Section: Connection Between the Deformation Modulus And The Strength mentioning

confidence: 99%

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Empirical methods of calculating the mechanical parameters of the rock mass

Vásárhelyi

Kovács²

2016

Period. Polytech. Civil Eng.

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The knowledge of the main mechanical constants of a rock mass (such as strength, deformability and the Poisson's ratio) is one of the most important for rock engineering design on or in rock mass. Until now, several empirical relationships were determined for calculating these material constants based on both the quality of the studied rock mass (ie. RMR or GSI values) IntroductionLarge scale rock mass characterization introduces material parameters related to mechanical properties. The most important properties are the deformation modulus; the unconfined strength and the Poisson's ratio value of the rock mass in interest. These material parameters are frequently related to laboratory data characteristics of intact rock samples and to the classical rock mass classification systems (e.g. RQD, Q, RMR or GSI). These rock mass quality measures quantify the relation between the rock mass and the intact rock.The established empirical relations between the mechanical parameters of rock masses (unconfined compressive strength, deformation modulus) and the rock mass classification systems (RMR or GSI values) show exponential increasing deformation modulus and compressive strength with the increasing quality of the rock mass.The paper summarizes the observed correlations published between the mechanical properties of rock masses and one of the rock mass classification systems. It was found, that the deformation modulus and the strength of a rock mass data may reflect a simple exponential relationship of the observed quantities. According to analysis of different proposed equations a new formula is suggested and the modification ratio (i.e. ratio of the deformation modulus and the strength of rock mass) is also determined.However, it is important to note, that there are huge differences between the published date and the empirical formulas. The reason for this variance is the difference in situ testing methods, that may give different values of mechanical parameters even for the same rock mass. According to Bieniawski [1], even a single testing method, such as flat jack test, can lead to a widely scattering results even where the rock mass is very uniform. The other reason for the discrepancy in the different calculation methods is the directional effect. Most rock masses are anisotropic and do not have single deformation modulus [2].There is no mechanical (physical) interpretation of the above empirical equations but these were analysed by e.g. [3]. Recently, Ván and Vásárhelyi [4] suggested a damage mechanical approach to analyse them. In this paper their method will be also presented.

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Section: Q Based Methodsmentioning

confidence: 99%

“…(17) i.e. This equation corresponds to another suggestion of Galera et al [17], which is based on pure empirical calculation. According to Eq.…”

Section: Normalized Equationsmentioning

confidence: 99%

Section: Independent Equationsmentioning

confidence: 99%

“…According to Galera et al [17], there is an expression involving both rock mass modulus (E m ) and rock mass strength (σ rm ):…”

Section: Connection Between the Deformation Modulus And The Strength mentioning

confidence: 99%

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Empirical methods of calculating the mechanical parameters of the rock mass

Vásárhelyi

Kovács²

2016

Period. Polytech. Civil Eng.

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“…The rock mass stiffness was predominantly derived using the results of laboratory tests and published empirical relationships using the following parameters: E i , RMR, UCS, GSI and D. The methods proposed by Hoek and Brown (2002), Hoek and Diederichs (2006) and Galera et al (2005) were used. The resulting rock mass stiffnesses were then validated against in situ pressuremeter test results.…”

Section: Rock Stiffnessmentioning

confidence: 99%

Geology and geotechnical evaluation of Doha rock formations

KaragkounisNikolaos¹,

LatapieBenoît²,

SayersKevin³

et al. 2016

Geotechnical Research

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A generalised ground model with geotechnical characterisation has been developed for the city of Doha, in Qatar, combining a wide range of ground investigation data and observations during the construction of projects that WS Atkins & Partners Overseas were involved with. The model proposes a geotechnical characterisation and ranges of parameters for the main units found at depths relevant to civil engineering activities. A geotechnical classification system is proposed to differentiate the Simsima Limestone subunits encountered on site, based on rock quality designation (RQD) values and weathering degree. The proposed classification system and the relevant geotechnical parameters have been validated during construction. The construction of all excavations, temporary retaining systems and tunnel excavations that rely on the information presented in this paper has been completed successfully. This confirmed a reasonable agreement between the theory presented in the paper and the practical conditions encountered on site. Best site investigation practices are discussed with highlights on difficulties encountered on site and how they were resolved. RQD and rock mass rating values were found to produce a good representation of the ground conditions while the applicability of the geological strength index classification is believed to be limited.

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Development of a Highly Portable Plate Loading Device and In Situ Modulus Measurements in Weak Rock Masses

et al. 2015

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In recent years, underground mines in Nevada are increasingly exploiting in weak mineralized zones at greater depths that are intensely fractured and highly altered. The mechanical behavior of these rock masses ranges between weak rock and very stiff soil. A common limitation for design of underground mining excavations in these types of rock masses is absence of in situ geotechnical data. This limitation is generally overcome by estimating in situ mechanical behavior from empirical relationships so that the continuum-based numerical methods can be used to evaluate ground support designs. Because of the cost, time, and specialized equipment involved, historically in situ tests have not been performed in these underground mines. Predictive rock mass modulus relationships that are currently available in the literature are derived from field testing of predominantly goodquality rock masses. Consequently, there is limited confidence in using these models for rock masses with Rock Mass Ratings less than 45. In order to overcome some of these limitations, a portable plate loading device (PPLD) was designed and fabricated. The PPLD allows one to perform low cost and relatively quick in situ deformability tests to be performed on weak rock masses in underground mines. Test procedures and data reduction methods were developed to limit potential sources of error associated with the PPLD test. A total of fourteen plate loading tests were performed in weak rock masses at two different active underground mines in Nevada, USA. The resulting the test data were compared to eight published empirical rock mass modulus relationships to determine which, if any, of these relationships are sufficiently accurate for estimating modulus in similar geotechnical conditions. Only two of these relationships were found to be sufficient for first-order estimations of in situ modulus.

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Evaluation of the deformation modulus of rock masses using RMR

Cited by 20 publications

References 2 publications

Empirical methods of calculating the mechanical parameters of the rock mass

Empirical methods of calculating the mechanical parameters of the rock mass

Geology and geotechnical evaluation of Doha rock formations

Development of a Highly Portable Plate Loading Device and In Situ Modulus Measurements in Weak Rock Masses

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