Intact rock and rock mass

2004 ◽  
pp. 16-42
Keyword(s):  
Rock Mass ◽  
Intact Rock

Static and Dynamic Elastic Modulus of Jointed Rock Mass

2010 ◽  
Vol 1 (2) ◽  
pp. 89-112
Author(s):  
T. G. Sitharam ◽  
M. Ramulu ◽  
V. B. Maji
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intact Rock ◽  
Rock Properties ◽  
Dynamic Elastic Modulus ◽  
Joint Factor ◽  
Joint Frequency ◽  
Joint Inclination

In this paper the compressive strength/elastic modulus of the jointed rock mass was estimated as a function of intact rock strength/modulus and joint factor. The joint factor reflects the combined effect of joint frequency, joint inclination and joint strength. Therefore, having known the intact rock properties and the joint factor, jointed rock properties can be estimated. The test results indicated that the rock mass strength decreases with an increase in the joint frequency and a sharp transition was observed from brittle to ductile behaviour with an increase in the number of joints. It was also found that the rocks with planar anisotropy exhibit the highest strength in the direction perpendicular to the anisotropy and the lowest at an inclination of 30o-45o in jointed samples. The anisotropy of the specimen influences the dynamic elastic modulus more than the static elastic modulus. The results were also compared well with the published works of different authors for different type of rocks.

Quasi-site-specific prediction for deformation modulus of rock mass

2020 ◽  
Author(s):  
Jianye Ching ◽  
Kok-Kwang Phoon ◽  
Yuan-Hsun Ho ◽  
Meng-Chia Weng
Keyword(s):  
Rock Mass ◽  
Bayesian Model ◽  
Deformation Modulus ◽  
Intact Rock ◽  
Transformation Model ◽  
Geological Strength Index ◽  
Hierarchical Bayesian ◽  
Hierarchical Bayesian Model ◽  
Rock Mass Rating ◽  
Site Specific

A generic rock mass database consisting of 9 parameters is compiled from 225 studies. The 9 parameters include the deformation modulus, elastic modulus, dynamic modulus, rock quality designation, rock mass rating, Q-system, geological strength index of a rock mass as well as intact-rock Young’s modulus and intact-rock uniaxial compressive strength. This generic database, labeled as ROCKMass/9/5876, consists of 5876 rock mass cases. The goal of this paper is to examine how an existing transformation model such as deformation modulus versus rock mass rating can be made more unbiased and more precise for a specific site by combining sparse site data with ROCKMass/9/5876 in a manner sensitive to site-specific differences. The outcome is a quasi-site-specific transformation model. Four methods are studied to construct a quasi-site-specific transformation model for the deformation modulus of a rock mass: probabilistic multiple regression (current state of practice), hybridization method, hierarchical Bayesian model, and similarity method. The results from two case studies in Turkey show that the hierarchical Bayesian model is the most effective.

scholarly journals A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

Geosciences ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 256 ◽  
Author(s):  
Davide Donati ◽  
Doug Stead ◽  
Davide Elmo ◽  
Lisa Borgatti
Keyword(s):  
Rock Mass ◽  
Laser Scanning ◽  
Preliminary Investigation ◽  
Intact Rock ◽  
Slope Instability ◽  
Numerical Analyses ◽  
Rock Fracturing ◽  
Bedding Planes ◽  
Synthetic Rock

The stability of high rock slopes is largely controlled by the location and orientation of geological features, such as faults, folds, joints, and bedding planes, which can induce structurally controlled slope instability. Under certain conditions, slope kinematics may vary with time, as propagation of existing fractures due to brittle failure may allow development of fully persistent release surfaces. In this paper, the progressive accumulation of brittle damage that occurred prior to and during the 2014 San Leo landslide (northern Italy) is investigated using a synthetic rock mass (SRM) approach. Mapping of brittle fractures, rock bridge failures, and major structures is undertaken using terrestrial laser scanning, photogrammetry, and high-resolution photography. Numerical analyses are conducted to investigate the role of intact rock fracturing on the evolution of kinematic freedom using the two-dimensional Finite-discrete element method (FDEM) code Elfen, and the three-dimensional lattice-spring scheme code Slope Model. Numerical analyses show that the gradual erosion of clay-rich material below the base of the plateau drives the brittle propagation of fractures within the rock mass, until a fully persistent, subvertical rupture surface form, causing toppling of fault-bounded rock columns. This study clearly highlights the potential role of intact rock fracturing on the slope kinematics, and the interaction between intact rock strength, structural geology, and slope morphology.

Static and Dynamic Elastic Modulus of Jointed Rock Mass

2012 ◽  
pp. 110-133
Author(s):  
T. G. Sitharam ◽  
M. Ramulu ◽  
V. B. Maji
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intact Rock ◽  
Rock Properties ◽  
Dynamic Elastic Modulus ◽  
Joint Factor ◽  
Joint Frequency ◽  
Joint Inclination

In this paper the compressive strength/elastic modulus of the jointed rock mass was estimated as a function of intact rock strength/modulus and joint factor. The joint factor reflects the combined effect of joint frequency, joint inclination and joint strength. Therefore, having known the intact rock properties and the joint factor, jointed rock properties can be estimated. The test results indicated that the rock mass strength decreases with an increase in the joint frequency and a sharp transition was observed from brittle to ductile behaviour with an increase in the number of joints. It was also found that the rocks with planar anisotropy exhibit the highest strength in the direction perpendicular to the anisotropy and the lowest at an inclination of 30o-45o in jointed samples. The anisotropy of the specimen influences the dynamic elastic modulus more than the static elastic modulus. The results were also compared well with the published works of different authors for different type of rocks.

Accelerated Diffusion Test on the Intact Rock Mass

2007 ◽  
Vol 35 (2) ◽  
pp. 100184 ◽  
Author(s):  
B Hanumantha Rao ◽  
A Dalinaidu ◽  
DN Singh
Keyword(s):  
Rock Mass ◽  
Intact Rock ◽  
Diffusion Test ◽  
Intact Rock Mass

The Effect of Joint Conditions on the Longitudinal and Flexural Wave Velocities of a Rock Mass

2006 ◽  
Vol 321-323 ◽  
pp. 306-309
Author(s):  
Min Su Cha ◽  
Young Jong Sim ◽  
Gye Chun Cho ◽  
Sung Won Lee
Keyword(s):  
Rock Mass ◽  
Jointed Rock ◽  
Intact Rock ◽  
Flexural Wave ◽  
Resonant Column ◽  
Near Surface ◽  
Wave Velocities ◽  
Jointed Rocks ◽  
Steel Base ◽  
Equivalent Continuum

The behavior of a jointed rock is different from that of an intact rock, and the characteristics of elastic wave propagation in a jointed rock are different from those of an intact rock. In this study, a rock resonant column testing device is designed to measure the longitudinal and flexural wave velocities of jointed rocks under different states of stress. A column of more than 12 rock discs is stacked on a steel base, which acts as a free-fixed system. This configuration ensures that waves propagate under an equivalent continuum condition, thereby rendering a constant and unique velocity. The effect of joint conditions on the wave velocities is investigated through rock resonant column testings. The results show that velocities are sensitive to the state of stress and increase nonlinearly with stress. The velocities are also affected by joint conditions such as roughness, spacing, and filling. The results are useful for rock mass classification based on near-surface geophysical characterization.

Instability in Himalayan Rock Slope under Recurrent Freeze-Thaw

2020 ◽  
Author(s):  
Sahil Sardana ◽  
Rabindra Kumar Sinha ◽  
Mamta Jaswal ◽  
Amit Kumar Verma ◽  
Trilok Nath Singh
Keyword(s):  
Rock Mass ◽  
Numerical Modelling ◽  
Rock Slope ◽  
Winter Season ◽  
Intact Rock ◽  
Joint Spacing ◽  
Freeze Thaw ◽  
Discontinuity Sets ◽  
Rock Structure ◽  
The Stability

<p>The highways in the Himalayas region have an important concern as these are the only connecting corridors to the nearby land area. Manali-Leh highway is one such important route in India which is interrupted frequently by landslides and rockslides events due to freeze-thaw activity, earthquake, heavy rainfall and anthropogenic activities are major triggering factors. In the freeze-thaw activity, water enters into the cracks in rocks during rainfall, subsequently, it freezes, leads to enlargement of cracks and/or the initiation of new cracks due to the volumetric expansion of ice. In the summer season, the ice melts and water migrates to the newly generated cracks and later freezes in the winter season. This, in turn, weakens the rock structure that leads to the reduction of the rock mass strength which promotes instability in the rock slopes. This study focuses on the stability assessment of rock slope along the highway from Solang Valley in Himachal Pradesh, India. This highway connects the Solang Valley to the south portal of the Rohtang tunnel and provides all-weather connectivity, as the Manali-Leh highway shut down during the winter season due to heavy snowfall.</p><p>An extensive geotechnical survey was carried out on the studied slope and the rock samples were collected from the field. The artificial freeze-thaw environment was created in the laboratory for the rock specimens to account the natural freeze-thaw effect. Laboratory tests were conducted on the rock specimen conditioned with freeze-thaw to determine the physico-mechanical parameters of intact rock prior to the numerical simulation. The results indicate the significant loss in compressive and tensile strength of rock as the number of freeze-thaw cycles increases. A three-dimensional numerical modelling was performed to assess the stability of the rock slope using the Distinct Element Code (3DEC software). Slope geometry was prepared to represent the actual slope and the various discontinuity sets observed at the field was mapped on the model. The behaviour of the discontinuity sets was modelled using a Mohr-Coulomb slip with residual strength. Normal stiffness of the joints was calculated from rock mass deformation modulus, intact rock young’s modulus and joint spacing. Similarly, the shear stiffness was calculated. The results of numerical modelling show that the displacement of blocks increases and the factor of safety of the slope decreases as the number of freeze-thaw cycles increases.</p>

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