Absorption of energy in cyclically loaded rock

2020 ◽  
pp. 429-434
Author(s):  
G.A. Rubin ◽  
M.F. Leach
Keyword(s):  
Loaded Rock

Statistical precursors of instability of loaded rock samples based on acoustic emission

1996 ◽  
Vol 33 (7) ◽  
pp. 743-748 ◽  
Author(s):  
V. Rudajev ◽  
J. Vilhelm ◽  
J. Kozák ◽  
T. Lokajíček
Keyword(s):  
Acoustic Emission ◽  
Rock Samples ◽  
Loaded Rock

In situ measurements of thermally loaded rock and evaluation of an experiment with a 3D numerical model

2018 ◽  
Vol 105 ◽  
pp. 1-10
Author(s):  
P. Rálek ◽  
K. Sosna ◽  
M. Hokr ◽  
J. Franěk
Keyword(s):  
Numerical Model ◽  
In Situ Measurements ◽  
Loaded Rock ◽  
3D Numerical Model

Damage Model and Damage Mechanical Characteristics of Loaded Rock under Freeze-Thaw Conditions

2010 ◽  
Vol 168-170 ◽  
pp. 658-662 ◽  
Author(s):  
Hui Mei Zhang ◽  
Geng She Yang
Keyword(s):  
Mechanical Properties ◽  
Structural Damage ◽  
Damage Mechanics ◽  
Coupling Effect ◽  
Damage Model ◽  
Engineering Structures ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Loaded Rock ◽  
Total Damage

Considering the heterogeneous characteristics of rock at mesoscopic level, the damage propagation constitutive relation and evolution equation of freeze-thaw and loaded rock were established by using the theory of macro phenomenological damage mechanics and the generalized theory of strain equality. The evolutionary mechanisms of micro-structural damage and materials mechanical properties for the loaded rock were discussed under freeze-thaw condition, verified by experimental results of the freeze-thaw cycle and compression test of rock. It is shown that the freeze-thaw and loaded damage model can represent the complicated relations among the freeze-thaw, load and the damage inside the rock, reveal the coupling failure mechanism of macroscopic rock under the freeze-thaw and load from the micro-damage evolution. The combined effect of freeze-thaw and load exacerbates the total damage of rock with obvious nonlinear properties, but the coupling effect weakens the total damage. The lithology and initial damage state of the freeze-thaw and loaded rock in engineering structures in cold regions determine the weights of influence factors to mechanical properties, including environmental factor, loading factor and the coupling effects, so the rock performances different damage mechanical characteristic.

Correlation Analysis of the Ultrasonic Emission from Loaded Rock Samples – the Study of Interaction of Microcracking Nucleation Centres

2006 ◽  
Vol 41 (5) ◽  
pp. 695-714 ◽  
Author(s):  
J. Vilhelm ◽  
V. Rudajev ◽  
T. Lokajíček ◽  
J. Veverka
Keyword(s):  
Correlation Analysis ◽  
Rock Samples ◽  
Ultrasonic Emission ◽  
Loaded Rock

scholarly journals THE RESULTS OF STUDIES OF THE DEPENDENCE OF THE PERFORMANCE OF THE VIBRATING TWO-SHAFT CENTRIFUGAL MODULE ON THE MODE AND DESIGN PARAMETERS

2019 ◽  
pp. 5-10
Author(s):  
Vladimir Naduty ◽  
Anastasia Loginova ◽  
Vitaliy Sukharev
Keyword(s):  
Rock Mass ◽  
Vibration Amplitude ◽  
Experimental Studies ◽  
Design Parameters ◽  
Crushed Rock ◽  
Experimental Sample ◽  
Elastic Supports ◽  
Loaded Rock ◽  
The Given

The article presents a new design of a vibrating twin-shaft centrifugal module designed for grinding and classification of rock mass. In this design, in addition to grinding, the operation of classification or screening of the crushed mass was added, which does not allow its regrinding and increases the productivity of the device. This is achieved by installing in the bottom of the chamber grinding mesh with cells in accordance with the required class size. At the same time, the classification process is intensified by the presence of vibration from vibration exciters fixed on the camera body and the installation of the camera on elastic supports. The reciprocating horizontal vibrations of the chamber with a given amplitude and frequency contribute to the segregation of the crushed rock mass in the bed by size, which positively affects the efficiency of classification and grinding. The presence of vibration helps to unload the oversize product from the grinding chamber. Also, the article considers experimental studies performed on a vibrational two-shaft centrifugal module to determine the dependence of the performance of a given design on five variable factors: rotor shaft revolutions (n, rpm), size of the loaded rock mass (Δ, mm), rock mass strength (σ, kg/mm2), camera vibration frequency (ω, rpm) and its vibration amplitude (A, mm). Studies have shown the efficiency and increased productivity of the new design in relation to a centrifugal disintegrator without a classification grid and vibration. The results of the work allow us to recommend the design under study for the manufacture of an experimental sample according to the given initial requirements, and the established dependences (Q = f (n, Δ, σ, ω, A) make it possible to develop a mathematical model of the grinding process in this setup to calculate the required parameters.

A Constitutive Model for Rock Joints under Cyclic Loading

2011 ◽  
Vol 243-249 ◽  
pp. 2211-2215
Author(s):  
Dong Mei Yang ◽  
Xiang Bo Qiu
Keyword(s):  
Constitutive Model ◽  
Mechanical Behaviour ◽  
Rock Joint ◽  
Joint Stiffness ◽  
Constitutive Models ◽  
Jointed Rock ◽  
Rock Joints ◽  
Cyclic Loads ◽  
Loaded Rock ◽  
Good Agreement

Cyclic loads are commonly encountered in geotechnical engineering; however most constitutive models do not account for the effect that such loads can have on the mechanical behaviour of soils and rocks. This work is concerned with the behaviour of jointed rock and, as the overall mechanical behaviour of jointed rock is usually dominated by the mechanical behaviour of the joints, it is focused on the behaviour of rock joints under cyclic loads. In particular, an extension of the existed constitutive model for cyclically loaded rock joints is presented. Variations of rock joint stiffness in both the normal and the shear directions of loading due to surface degradation are taken into account. The degradation of asperities of first and second order is considered, while a new relation is proposed for the joint stiffness in the normal direction during unloading. Numerical simulation results show good agreement of model predictions with existing experimental results.

Une nouvelle technique d'inclusion pour la mesure à long terme des déformations dans des barrages en béton

1990 ◽  
Vol 17 (6) ◽  
pp. 919-930 ◽  
Author(s):  
Gérard Ballivy ◽  
Brahim Benmokrane ◽  
Roch Poulin ◽  
Kaveh Saleh
Keyword(s):  
Strain Gauges ◽  
Drilling Process ◽  
Rock Slopes ◽  
Concrete Dams ◽  
Vibrating Wire ◽  
Diameter Hole ◽  
Concrete Blocks ◽  
Loaded Rock ◽  
Rock Pillars

This paper presents the results of an experimental study on the development of a simple yet efficient technique allowing for the long-term measurements of strains and stresses in working concrete dams. The proposed technique consists of installing a cylindrical concrete inclusion instrumented with vibrating wire gauges embedded into the concrete. The 140-mm cylinder is slipped into a 152 mm diameter hole, which is drilled into the dam and then filled with cement grout. This technique, which was tested in the laboratory on instrumented concrete blocks, has shown that it is now possible to measure the deformation variations in a working dam. The inclusion can be instrumented for both bidimensional and tridimensional cases. The volume of the cylinder makes room for a sufficient number (4–8) of vibrating wire gauges. Moreover, during the drilling process, the technique of overcoring makes it possible to determine the initial total stresses. This technique can also be used to instrument heavily loaded rock structures such as mine pillars or underground gallery walls. Current observations show that this technique, contrary to plastic inclusions, can be considered appropriate for permanent structures. Key words: vibrating wire gauges, strain gauges, instrumentation, strain measurements, long term, concrete dams, rock slopes, rock pillars, mines, underground excavations.

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