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.

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.

Intelligent Models Applied to Elastic Modulus of Jointed Rock Mass

2018 ◽  
pp. 1-30 ◽  
Author(s):  
Jagan Jayabalan ◽  
Sanjiban Sekhar Roy ◽  
Pijush Samui ◽  
Pradeep Kurup
Keyword(s):  
Neural Network ◽  
Rock Mass ◽  
Elastic Modulus ◽  
Roughness Parameter ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Artificial Neural Network Ann ◽  
Learning Machine ◽  
Hidden Layer ◽  
Intelligent Models

Elastic Modulus (Ej) of jointed rock mass is a key parameter for deformation analysis of rock mass. This chapter adopts three intelligent models {Extreme Learning Machine (ELM), Minimax Probability Machine Regression (MPMR) and Generalized Regression Neural Network (GRNN)} for determination of Ej of jointed rock mass. MPMR is derived in a probability framework. ELM is the modified version of Single Hidden Layer Feed forward network. GRNN approximates any arbitrary function between the input and output variables. Joint frequency (Jn), joint inclination parameter (n), joint roughness parameter (r), confining pressure (s3) (MPa), and elastic modulus (Ei) (GPa) of intact rock have been taken as inputs of the ELM, GRNN and MPMR models. The output of ELM, GRNN and MPMR is Ej of jointed rock mass. In this study, ELM, GRNN and MPMR have been used as regression techniques. The developed GRNN, ELM and MPMR have been compared with the Artificial Neural Network (ANN) models.

scholarly journals Aziznejad, S. and Esmaieli, K. 2015. Effects of joint intensity on rock fragmentation by impact, 11th International Symposium on Rock Fragmentation by Blasting, 24-26 August, Sydney, Australia

2017 ◽  
Author(s):  
Kamran Esmaieli
Keyword(s):  
Rock Mass ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Rock Fragmentation ◽  
Intact Rock ◽  
Particle Model ◽  
Rock Masses ◽  
Dynamic Mechanical ◽  
Bonded Particle Model ◽  
The Impact

Impact-induced rock fragmentation is a mechanism that is commonly used for rock breakage in drilling andcrushing. Additionally, rock fragmentation by blasting is frequently used in rock excavation operations.Experience shows that presence of discontinuities in rock can significantly influence the impact-induceddamage and fragmentation of rock. Quantification of the response of jointed rock masses to impact loads iscomplicated by the fact that the available laboratory tests are mainly designed for aggregates or intact rocks.It can be argued that neither of these tests adequately represent a jointed rock mass. This paper presentsthe results of a series of numerical simulations used to investigate the influence of pre-existingdiscontinuities on the impact-induced fragmentation of rock masses. The methodology includesdetermination of the static and dynamic mechanical properties of a rock unit by conducting a series oflaboratory tests on intact rock samples collected from a quarry in Canada. A 2D distinct element code,Particle Flow Code (PFC2D), was used to generate a bonded particle model in order to simulate both staticmechanical properties (Uniaxial Compressive Strength, Elastic Modulus, Poisson’s Ratio and indirect TensileStrength) and dynamic mechanical property (drop weight tensile strength) of the intact rock. The calibratednumerical model was then used to construct large-scale synthetic rock mass samples by incorporatingdiscontinuity networks of different intensity into the bonded particle model. Finally, the impact-inducedfragmentation inflicted by a rigid projectile particle on the jointed rock mass samples, simulated by asynthetic rock mass model, was determined. More fragmentation was observed for the rock mass sampleswith higher joint intensity.

Experimental Study of Mechanical Properties of Rock Mass Containing Intermittent Joints of Prefabricated

2010 ◽  
Vol 168-170 ◽  
pp. 2468-2472 ◽  
Author(s):  
Rui Hong Wang ◽  
Jian Lin Li ◽  
Jing Guo ◽  
Yu Zhou Jiang ◽  
Li Dang
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Ultimate Strength ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intact Rock ◽  
Rock Masses ◽  
Intact Rock Mass

Most of the engineering rock masses contain a variety of different levels of geological tectonic joints and weak planes, which can weaken the rock strength. The rock masses containing joints have completely different mechanical properties with the intact ones. Through loading failure tests on the rock masses containing two intermittent joints of prefabricated of different spacing, the differences between jointed rock mass and intact one were studied. The research shows that: 1. Comparing with the intact rock mass, the stress-strain curve of jointed one has a relatively large fluctuation near the peak, it isn’t smooth, and there's a reduction in the stage of plastic flow after yielding; ultimate strength decreases obviously, joint depth has a great impact on strength, and there's no necessary link between ultimate strength of rock mass and joints spacing. 2. When the loading is failure, the elastic and deformation modulus of rock mass decrease obviously comparing with those of the intact rock mass, which tend small generally with the increment of joints spacing, however, they have a relatively complex relation and it isn't linear. 3. The failure characteristics of jointed rock mass are different from those of the intact rock mass, failure planes are relatively complex and no longer single shear or complementary shear ones, which presents that shear failures occur along the end of prefabricated joints with few extensional cracks; the spacing of prefabricated joints have a great impact on the failure pattern of rock mass. The research results can provide certain references for the mechanical parameters selection of jointed rock mass of engineering design and numerical analysis.

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