Long-term behaviour of complex underground structures in evaporitic rock mass – Experiences gained from calculations and geotechnical observations

2018 ◽  
Vol 78 ◽  
pp. 159-167 ◽  
Author(s):  
Gunter G. Gschwandtner ◽  
Robert Galler
Keyword(s):  
Rock Mass ◽  
Underground Structures

scholarly journals Design of underground structures and analysis of self-support capacity

2018 ◽  
Vol 65 (2) ◽  
pp. 59-70
Author(s):  
Matej Nagy
Keyword(s):  
Rock Mass ◽  
Hard Rock ◽  
In Situ Stress ◽  
Stability Control ◽  
Underground Structures ◽  
Underground Powerhouse ◽  
The Stability ◽  
Methods Numerical

Abstract The complicated rock structures and the stability of surrounding rocks of the underground powerhouse are key ground mechanical challenges for hydropower projects. In this paper, an example of contributing self-support capacity of rock mass to evaluate optimised support for long-term usage of structure is given. It describes importance of investigations in the initial in situ stress distribution, rock mechanical and geological properties, engineering rock mass classifications by different methods, numerical modelling, comparison of tools for stability and support analysis and proper stability control for rock excavation and support. The results show that after underground excavations in hard rock, detailed analysis of measures to investigate deformation and self-supporting capacity creation is useful and a cost-saving procedure.

In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

2004 ◽  
Vol 261-263 ◽  
pp. 1097-1102 ◽  
Author(s):  
Jian Liu ◽  
Xia Ting Feng ◽  
Xiu Li Ding ◽  
Huo Ming Zhou
Keyword(s):  
Rock Mass ◽  
Creep Behavior ◽  
Large Scale ◽  
Time Dependent ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

scholarly journals Observation of the rock slope thermal regime, coupled with crack meter stability monitoring

2021 ◽  
Author(s):  
Ondřej Racek ◽  
Jan Blahůt ◽  
Filip Hartvich
Keyword(s):  
Rock Mass ◽  
Monitoring System ◽  
Rock Slope ◽  
Global Radiation ◽  
Environmental Parameters ◽  
Radiation Balance ◽  
Rock Types ◽  
Novel Approach ◽  
First Results

Abstract. This article describes an innovative, complex and affordable monitoring system designed for joint observation of environmental parameters, rock block dilatations and temperature distribution inside the rock mass with a newly designed 3-meter borehole temperature sensor. Global radiation balance data are provided by pyranometers. The system introduces a novel approach for internal rock mass temperature measurement, which is crucial for the assessment of the changes in the stress field inside the rock slope influencing its stability. The innovative approach uses an almost identical monitoring system at different sites allowing easy setup, modularity and comparison of results. The components of the monitoring system are cheap, off-the-shelf and easy to replace. Using this newly designed system, we are currently monitoring three different sites, where the potential rock fall may endanger society assets below. The first results show differences between instrumented sites, although data time-series are relatively short. Temperature run inside the rock mass differs for each site significantly. This is very likely caused by different aspects of the rock slopes and different rock types. By further monitoring and data processing, using advanced modelling approaches, we expect to explain the differences among the sites, the influence of rock type, aspect and environmental variables on the long-term slope stability.

scholarly journals Determination and quality classification of rock mass of the Diatomite mine, Algeria

2021 ◽  
Vol 1 ◽  
pp. 17-24
Author(s):  
Abdessattar LAMAMRA ◽  
◽  
Dmitriy Leonidovich NEGURITSA ◽  
Samir BEDR ◽  
Ariant A. REKA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Underground Mining ◽  
Physical And Mechanical Properties ◽  
Friction Angle ◽  
Classification Systems ◽  
Natural Phenomenon ◽  
Underground Structures ◽  
Dilatancy Angle ◽  
Mining Work

Reserch relaevance. Most ground movements are generally due to rock instability, this natural phenomenon poses a risk to humanity. The properties of the rock mass directly influence the type of movement especially in underground structures. Research aim. Our goal is to characterize and classify the rock mass of diatomite from the sig mine using geomechanical classification systems such as the RQD and RMR in order to determine the quality of the rocks in the sig mine Western Algeria from the determination of the physical and mechanical properties. Methodology. In this article, the characterization analysis of the diatomite rock mass of the sig mine was carried out. First, determinations of the physical properties and carried out the triaxial test to determine the mechanical properties (young’s modulus, the friction angle, the dilatancy angle, the cohesion, the poisson’s ratio). Secondly to classify the deposit and give a recommendation to avoid stability problems. Research results. The results from physical and mechanical analyzes, it can be said that the nature of the rock present in the diatomite (underground mine) does not have enough resistance. Conclusion. Our study definitively proves that the rock mass of sig diatomite is of very low quality and it will be very dangerous for the underground mining work of the mine especially in places where the mineralized layer is very deep. And we suggest to replace the mining technique room and pillar currently used in the diatomite mine and put another mining method which includes roof support system to ensure the safety both of the miners and the equipment.

Application of Numerical and Block Geomechanical Modelling to Determine Parameters of Large-Section Chambers

2021 ◽  
pp. 127-131
Author(s):  
M.A. Sonnov ◽  
A.V. Trofimov ◽  
A.E. Rumyantsev ◽  
S.V. Shpilev
Keyword(s):  
Rock Mass ◽  
Strain State ◽  
Stress And Strain ◽  
Underground Structures ◽  
Geomechanical Model ◽  
Principal Stresses ◽  
Mine Support ◽  
History Of ◽  
Crushing Plant ◽  
Ore Pass

The study is exemplified by complex workings of a main ore pass that include a variety of underground structures, usually with unique dimensions which depend on the function and size of the equipment placed. The technical solutions for the underground crushing plant and associated structures envisage construction of chambers with the height of up to 35 m and the width of up to 20 m at the depths exceeding 800-1000 m. Such conditions call for a closer attention to be paid to the mine support parameters, especially the bolting depth. A block geomechanical model was designed in the Micromine Mining Software for the rock mass of the new main ore pass. Geotechnical boreholes logs and results of physical and mechanical rock tests were used as the input data for the model. Four domains were identified in the block geomechanical model for subsequent numerical modelling. A 3D model of the stress-and-strain state of the rock mass was made using the CAE Fidesys software based on the Micromine wire-frame model of the main ore pass. The history of the rock mass incremental loading was reconstructed for correct simulation of its stress-and-strain state. Prior to the excavation, the rock mass is pre-stressed by the weight of the rock strata. The excavation phase was then simulated in the stepwise manner. An array of points with the values of maximum principal stresses was downloaded from the numerical model post-processing program and interpolated into the block geomechanical model to refine the SRF parameter of the Barton's Q rating. Based on the obtained Q values, the mine support parameters for chambers were determined using the Barton, Hutchinson and Potvin empirical methods.

Of forming loads on the mounting of shaft shafts in the hierarchic block environment under the influence of modern geodynamic movements

2020 ◽  
pp. 161-169
Author(s):  
I. L. Ozornin ◽  
A. E. Balek ◽  
A. N. Kaiumova
Keyword(s):  
Rock Mass ◽  
High Stress ◽  
Surrounding Rock ◽  
Strain Behavior ◽  
Underground Openings ◽  
Hierarchical Block Structure ◽  
The Subject ◽  
Nonuniform Stress Field ◽  
Strength Rock

The subject of the research is the lining of mine shafts and surrounding rock mass. The subject matter is the features of the stress-strain behavior of lining and adjacent rock mass in shafts and near-shaft underground openings in the Tenth Anniversary of Independence of Kazakhstan mine located in the tectonically high-stress and low-strength rock mass. The loading of the lining in the shafts and near-shaft openings in the Tenth Anniversary of Independence of Kazakhstan mine during construction is investigated, and the damages of the lining in the course of drivage in the nonuniform stress field are analyzed. The long-term periodic in-situ instrumental monitoring of stress variation in the lining of the mine shafts and near-shaft openings revealed the main influences on the process of load formation on the lining in the conditions of post-limiting deformation of surrounding rock mass. It is validated that the surrounding rock mass of the mine has a complex hierarchical block structure and is subjected to modern geodynamic movements. As the depth of mining is increased, surrounding rock mass of the mine shafts transfers to the condition of postlimiting stresses and strains. As a consequence, the lining of the shafts and near-shaft openings at different stages of construction experiences nonuniform concentrated loads, which violates integrity of the lining.

Integrated geophysical and geotechnical monitoring for multiscale rock mass damaging investigation at the Acuto Field-Lab (Italy)

2021 ◽  
Author(s):  
Guglielmo Grechi ◽  
Danilo D'Angiò ◽  
Matteo Fiorucci ◽  
Roberto Iannucci ◽  
Luca Lenti ◽  
...  
Keyword(s):  
Rock Mass ◽  
Monitoring System ◽  
Thermal Stresses ◽  
Central Italy ◽  
Jointed Rock ◽  
Failure Behavior ◽  
Rock Masses ◽  
Geotechnical Monitoring ◽  
Strain Monitoring

<p>Rock mass damaging has become a topic of great interest in the engineering-geology research community during the last decades as it can significantly influence slopes stability. In this sense, the study of mechanics and dynamics of jointed rock masses represents a challenge because it will allow to better understand how external continuous and transient stressors can influence the short- to long-term stability controlling their pre-failure behavior. Consequently, the detection of permanent changes in physical and mechanical parameters, due to periodic or transient stressors, is an important target to mitigate the related geological risk as it can potentially lead rock masses to failure, especially when infrastructures and natural or cultural heritages are exposed elements. In this framework, the Acuto field laboratory (Central Italy) has been designed and implemented in 2016 within an abandoned quarry by employing an integrated geotechnical and geophysical monitoring system, with the aim of investigating how natural and anthropic conditioning factors could lead fractured rock masses to failure. The integrated monitoring system, which is installed on a potentially unstable 20-m<sup>3</sup> jointed rock block, is composed of several strain devices (i.e., strain gauges -SG- and jointmeters -JM-), one fully equipped weather station, one rock thermometer, eight high-sensitivity microseismic uniaxial accelerometers and optical and InfraRed Thermal cameras. The acquisition of long-term monitoring time-series, coupling multimethodological approaches, allowed to establish cause-to-effect relationships among different environmental stressors and induced strain effects, highlighting the continuous action of thermal stresses on rock mass deformations both at the daily and seasonal timescales. In fact, while the analysis of thermal and strain monitoring data allowed to characterize the cyclic contraction and relaxation response of major rock fractures and microcracks to temperature fluctuations, the microseismic monitoring array was able to detect during thermal transient (i.e., freezing conditions) the occurrence of microseismic emissions potentially related to the genesis or progressive growth of pre-existing cracks.</p><p>Starting from 2018, experimental activities at the Acuto field lab are supported by the “Dipartimento di Eccellenza” project of the Italian Ministry of Education Universities and Research funds attributed to the Department of Earth Sciences of the University of Rome “Sapienza”.  In this framework, the Acuto filed laboratory will undergo a structural upgrade that will be aimed at the investigation of two new sectors of the abandoned quarry. These new sectors will be instrumented with innovative thermal profiles probe, fiber Brag grating sensors and traditional SG and JM for detailed stress-strain monitoring, acoustic emission sensors and high-frequency and low-frequency geophones for ambient seismic noise monitoring and microseismic events detection as well as accelerometers for evaluating the rock mass response in the case of seismic shaking. The main goal of such an improvement will be both technical and methodological, and will shed light on the application of integrated geophysical and geotechnical monitoring approaches in investigating the multiscale rock mass damaging process as well as the detection of rock mass failure precursors by using non-conventional combinations and configurations of geotechnical and broad-band geophysical devices.</p>

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