scholarly journals Estimation of Regional Stress for Heterogeneous Rock Mass

2003 ◽  
Vol 119 (10,11) ◽  
pp. 655-662 ◽  
Author(s):  
Naoki KIMURA ◽  
Koji MATSUKI ◽  
Shigeo NAKAMA ◽  
Toshinori SATO
Keyword(s):  
Rock Mass ◽  
Regional Stress ◽  
Heterogeneous Rock

scholarly journals Determination of Mechanical Properties of Altered Dacite by Laboratory Methods

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 813
Author(s):  
Veljko Rupar ◽  
Vladimir Čebašek ◽  
Vladimir Milisavljević ◽  
Dejan Stevanović ◽  
Nikola Živanović
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rock Mass ◽  
Uniaxial Compressive Strength ◽  
Rock Material ◽  
Strength Parameter ◽  
Gradual Transition ◽  
Strength Parameters ◽  
Triaxial Compressive Strength ◽  
Heterogeneous Rock

This paper presents a methodology for determining the uniaxial and triaxial compressive strength of heterogeneous material composed of dacite (D) and altered dacite (AD). A zone of gradual transition from altered dacite to dacite was observed in the rock mass. The mechanical properties of the rock material in that zone were determined by laboratory tests of composite samples that consisted of rock material discs. However, the functional dependence on the strength parameter alteration of the rock material (UCS, intact UCS of the rock material, and mi) with an increase in the participation of “weaker” rock material was determined based on the test results of uniaxial and triaxial compressive strength. The participation of altered dacite directly affects the mode and mechanism of failure during testing. Uniaxial compressive strength (σciUCS) and intact uniaxial compressive strength (σciTX) decrease exponentially with increased AD volumetric participation. The critical ratio at which the uniaxial compressive strength of the composite sample equals the strength of the uniform AD sample was at a percentage of 30% AD. Comparison of the obtained exponential equation with practical suggestions shows a good correspondence. The suggested methodology for determining heterogeneous rock mass strength parameters allows us to determine the influence of rock material heterogeneity on the values σciUCS, σciTX, and constant mi. Obtained σciTX and constant mi dependences define more reliable rock material strength parameter values, which can be used, along with rock mass classification systems, as a basis for assessing rock mass parameters. Therefore, it is possible to predict the strength parameters of the heterogeneous rock mass at the transition of hard (D) and weak rock (AD) based on all calculated strength parameters for different participation of AD.

scholarly journals An analysis on the slaking and disintegration extent of weak rock mass of the water tunnels for hydropower project using modified slake durability test

2019 ◽  
Vol 79 (4) ◽  
pp. 1919-1937 ◽  
Author(s):  
Lena Selen ◽  
Krishna Kanta Panthi ◽  
Gunnar Vistnes
Keyword(s):  
Rock Mass ◽  
Test Method ◽  
Weak Rock ◽  
Hydropower Project ◽  
Durability Test ◽  
Slake Durability ◽  
Operational Life ◽  
Heterogeneous Rock ◽  
Weak Rock Mass ◽  
Slake Durability Test

AbstractWater tunnels built for hydropower passing through weak and heterogeneous rock mass pose challenges associated to slaking and disintegration, as they are first exposed to dry condition during excavation and are then filled with water to produce hydropower energy. Over the period of operational life, these tunnels are drained periodically for inspections and repair leading to drainage and filling cycles. The weakening of rock mass caused by cycles of drying, saturation and drainage may lead to the propagation of instabilities in the tunnels. Therefore, it is important to study the slaking and disintegration behavior of the weak rock mass consisting of clay and clay-like minerals. This paper assesses the mineralogical composition of flysch and serpentinite from the headrace tunnel of Moglicë Hydropower Project in Albania. Further, to determine the slaking and disintegration behavior of these rocks, extensive testing using both the ISRM, Int J Rock Mech Min Sci Geomech Abstr 16(2):143-151, (1979) suggested test method and a modified variant of this test are performed. Finally, comprehensive assessments, discussions and comparisons are made. It is found that the modified slake durability test better suits for the tunnels built as water conveying systems such as hydropower tunnels.

GAS EMISSION FROM THE SURFACE OF THE ROCK DUMPS

2021 ◽  
Vol 1 (1) ◽  
pp. 45-52
Author(s):  
STAS G.V. ◽  
◽  
ROZHKOV V.F. ◽  
SOKOLOVA S.S. ◽  
BORODKINA N.N. ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Rock Mass ◽  
Organic Compounds ◽  
Mathematical Description ◽  
Physical Models ◽  
Gas Emission ◽  
Environmental Models ◽  
Physicochemical Processes ◽  
Heterogeneous Rock ◽  
Pollutant Migration

Rock dumps are formed from a heterogeneous rock mass, in which, due to its crushing and mixing in the presence of air oxygen, physicochemical processes are activated. The dumps are characterized by significant emission of gases and dust into the atmosphere. Environmental models of dumps and geo-technological periods of mine operation have been developed, which are the basis for physical models of pollutant migration processes and their mathematical description. Sources of emission of gas hazards from the surfaces of dumps of coal mines are the centers of combustion of the dump mass, which contains large quantities of organic compounds. The developed model of the mass transfer of gases emitted from the combustion center makes it possible to estimate the gross and maximum one-time emissions of pollutants into the atmosphere from the surface of burning dumps.

scholarly journals Assessing TBM performance in heterogeneous rock masses

2021 ◽  
Author(s):  
Sarah Sissins ◽  
Chrysothemis Paraskevopoulou
Keyword(s):  
Rock Mass ◽  
Heterogeneous Environments ◽  
Rock Masses ◽  
Tbm Performance ◽  
Machine Performance ◽  
Heterogeneous Rock ◽  
Layered Rock Mass ◽  
Heterogeneous Rock Masses ◽  
Mineral Transport ◽  
The Uk

AbstractA major challenge that TBM performance is requested to deal with for a successful and effective progress is tunnelling through lithologically and geomechanically heterogeneous rock masses. Such heterogeneous environments are common and recent tunnel examples in the UK include the Hinckley Point C offshore cooling tunnels being driven through interbedded carbonaceous mudstone/shales and argillaceous limestone and the Anglo American’s Woodsmith Mine Mineral Transport System tunnel in Redcar Mudstone with beds of ironstone. This inherent geological heterogeneity leads to difficult tunnelling conditions that initially stem from predicting a sound and representative ground model that can be used to preliminary assess the TBM performance. In this work, an exhaustive review of existing TBM Penetration Rate (PR) methods identified that no models address the issue of parameter selection for heterogeneous rock masses comprising layers with different rock strengths. Consequently, new approaches are required for estimating rock mass behaviour and machine performance in such environments. In the presented work the Blue Lias Formation (BLI), which is characterised by its layered rock mass, comprising very strong limestone, interbedded with weak mudstone and shales, is investigated. BLI formation is considered herein being a representative example of lithological heterogeneity. Based on the fieldwork carried out in three localities in the Bristol Channel Basin (S. Wales and Somerset), geological models are produced based on which a geotechnical model is developed, and four ground types are determined. Implications of the current findings for TBM performance are assessed, including faulting, groundwater inflow and excavation stability with a particular focus on both PR and advance rate. A modified approach using the existing empirical models is proposed, developed and presented in this paper that can be used as a guide to determine TBM performance in heterogeneous rock masses reducing the risk of cost and time overruns.

Discussions on Zonal Disintegration around Tunnel in Deep Rock Mass

2012 ◽  
Vol 594-597 ◽  
pp. 2285-2289 ◽  
Author(s):  
Peng Jia ◽  
Tian Hong Yang ◽  
Chun Ming Zhang
Keyword(s):  
Rock Mass ◽  
Laboratory Test ◽  
Stress Level ◽  
Hydrostatic Stress ◽  
Axial Stress ◽  
Numerical Code ◽  
Zonal Disintegration ◽  
Heterogeneous Rock ◽  
Deep Rock ◽  
Adjacent Fractures

Questions related to zonal disintegration such as difference between results from laboratory test and field monitoring test, as well as the effect of multi-axial stress level on zonal disintegration were discussed through numerical modeling by using a 3D numerical code called RFPA3D. Results show that the much smaller fracture spacing captured by laboratory test on zonal disintegration is due to the heterogeneity extent of the tested material. Zonal disintegration is an inherent character of heterogeneous rock mass, the more the heterogeneous the rock is, the larger the spacing between the adjacent fractures will be. The configuration of zonal disintegration is influenced by combination of stress level in three directions. Intact fracture rings can not be formed unless a nearly hydrostatic stress state exists in directions perpendicular to tunnel axis.

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