scholarly journals Methods Applied in the Prediction of Brittle Failure in Tunnels and Underground Caverns

2018 ◽  
Vol 22 ◽  
pp. 5-9
Author(s):  
Krishna Kanta Panthi
Keyword(s):  
Rock Mass ◽  
Rock Burst ◽  
Brittle Failure ◽  
In Situ Stress ◽  
Rock Cover ◽  
Underground Caverns ◽  
Rock Burst Prediction ◽  
Stress Environment

Tunnels and underground caverns located at greater depth (high rock cover or overburden) are subjected to high in-situ stress environment. Those rock mass that are relatively unjointed and massive are exposed to the brittle failure, which is famously known as rock spalling/ rock bursting phenomenon. Establishing state of the stress and evaluating stress-induced instability in tunnels passing through such rock mass at relatively greater depth is therefore a challenge. The aim of this manuscript is to describes existing brittle failure (rock burst) prediction methods that are being practiced worldwide and propose necessary editions so that quality of assessment is enhanced. The methods described are very practical and the author is confident that professional engineers will use them to evaluate and predict potential rock burst/ rock spalling scenario in the tunnels during planning, design and construction phases. Each method of prediction is explained, applicability extent is highlighted and comparisons between the methods are made.  HYDRO Nepal JournalJournal of Water Energy and EnvironmentIssue No: 22Page: 5-9Uploaded date: January 14, 2018

Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

2013 ◽  
Vol 838-841 ◽  
pp. 705-709
Author(s):  
Yun Hao Yang ◽  
Ren Kun Wang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Damage Model ◽  
Back Analysis ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
High In Situ Stress ◽  
Underground Caverns ◽  
The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

scholarly journals Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
XinPing Li ◽  
JunHong Huang ◽  
Yi Luo ◽  
Qian Dong ◽  
YouHua Li ◽  
...  
Keyword(s):  
Rock Mass ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Finite Element Software ◽  
Underground Cavern ◽  
Underground Caverns ◽  
Blasting Excavation

Aiming at surrounding rock damage induced by dynamic disturbance from blasting excavation of rock-anchored beam in rock mass at moderate or far distance in underground cavern, numerical model of different linear charging density and crustal stress in underground cavern is established by adopting dynamic finite element software based on borehole layout, charging, and rock parameter of the actual situation of a certain hydropower station. Through comparison in vibration velocity, contour surface of rock mass excavation, and the crushing extent of excavated rock mass between calculation result and field monitoring, optimum linear charging density of blast hole is determined. Studies are also conducted on rock mass vibration in moderate or far distance to blasting source, the damage of surrounding rock in near-field to blasting source, and crushing degree of excavated rock mass under various in situ stress conditions. Results indicate that, within certain range of in situ stress, the blasting vibration is independent of in situ stress, while when in situ stress is increasing above certain value, the blasting vibration velocity will be increasing and the damage of surrounding rock and the crushing degree of excavated rock mass will be decreasing.

Analysis of TBM Tunnel Behavior in Jointed Rock Mass

2011 ◽  
Vol 90-93 ◽  
pp. 2033-2036 ◽  
Author(s):  
Jin Shan Sun ◽  
Hong Jun Guo ◽  
Wen Bo Lu ◽  
Qing Hui Jiang
Keyword(s):  
Rock Mass ◽  
Numerical Models ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Joint Orientation ◽  
Joint Spacing ◽  
Factors Affecting ◽  
Dip Angle

The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

scholarly journals Stability Assessment of Mining Excavations: the Impact of Large Depths

2018 ◽  
Vol 40 (3) ◽  
pp. 180-187
Author(s):  
Tadeusz Majcherczyk ◽  
Zbigniew Niedbalski ◽  
Łukasz Bednarek
Keyword(s):  
Rock Mass ◽  
In Situ Monitoring ◽  
Stability Assessment ◽  
Underground Excavations ◽  
Deformation Prediction ◽  
Large Depth ◽  
Coal Deposits ◽  
The Impact

AbstractBack in the early 1980s, coal deposits occurring at depths of ~700 m below surface were already regarded as large-depth deposits. Meanwhile, today the borderline depth of large-depth mining has extended to >1,000 m. Design, excavation and maintenance of mining roadways at the depth of >1,000 m have, therefore, become crucial issues in a practical perspective in recent years. Hence, it is now extremely important to intensify research studies on the influence of large depths on the behaviour of rock mass and deformation of support in underground excavations. The paper presents the results of the study carried out in five mining excavations at depths ranging from 950 to 1,290 m, where monitoring stations with measurement equipment were built. The analysis of data from laboratory and coal mine tests, as well as in situ monitoring, helped to formulate a set of criteria for stability assessment of underground excavations situated at large depths. The proposed methodology of load and deformation prediction in support systems of the excavations unaffected by exploitation is based on the criteria referring to the depth of excavation and the quality of rock mass. The depth parameter is determined by checking whether the analysed excavation lies below the critical depth, whereas the rock mass quality is determined on the basis of the roof lithology index (WL) and the crack intensity factor (n)

The Application of Hydraulic Fracturing in Storage Projects of Liquefied Petroleum Gas

2006 ◽  
Vol 306-308 ◽  
pp. 1509-1514 ◽  
Author(s):  
Jing Feng ◽  
Qian Sheng ◽  
Chao Wen Luo ◽  
Jing Zeng
Keyword(s):  
Rock Mass ◽  
Hydraulic Fracturing ◽  
Stress Measurement ◽  
Test Procedure ◽  
In Situ Stress ◽  
Test System ◽  
Petroleum Engineering ◽  
Liquefied Petroleum Gas

It is very important to study the pristine stress field in Civil, Mining, Petroleum engineering as well as in Geology, Geophysics, and Seismology. There are various methods of determination of in-situ stress in rock mass. However, hydraulic fracturing techniques is the most convenient method to determine and interpret the test results. Based on an hydraulic fracturing stress measurement campaign at an underground liquefied petroleum gas storage project which locates in ZhuHai, China, this paper briefly describes the various uses of stress measurement, details of hydraulic fracturing test system, test procedure adopted and the concept of hydraulic fracturing in arriving at the in-situ stresses of the rock mass.

scholarly journals Rock Mass Behavior under Tunnel Widening in Asymmetric and Symmetric Modes Considering Different Shapes and Parametric Conditions

Geosciences ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 518
Author(s):  
Babar Khan ◽  
Syed Muhammad Jamil ◽  
Jung Joo Kim ◽  
Turab H. Jafri ◽  
Jonguk Kim
Keyword(s):  
Rock Mass ◽  
In Situ Stress ◽  
Design Parameters ◽  
Tunnel Widening ◽  
Tunnel Support ◽  
Mass Behavior ◽  
Rock Types ◽  
The Difference ◽  
Support Conditions

To accommodate traffic volume on roads due to ever-increasing population growth, the widening of highways and motorways is in high demand. Nevertheless, the widening of tunnels on these road networks is quite complex due to the presence of numerous rock types, in situ stress, and different widening modes. To overcome these complexities, eight different tunnel shapes were simulated under varying support conditions for asymmetric and symmetric widening. It was found that the tunnels with a round shape, such as horseshoe and semicircular with flatbed, are more effective for asymmetric widening, whereas the provision of a rounded invert in these shapes can reverse the widening option to symmetric. Furthermore, an insignificant effect of the difference in asymmetric and symmetric widening of regular tunnel shapes, such as box, rectangular, and semi-elliptical, was found. A full factorial design statistical analysis confirmed the decrease in tunnel deformation by using various tunnel support systems and showed a significant deformation difference according to monitoring locations at the tunnel periphery. The deformation difference in the case of both tunnel widening modes was also analyzed according to different design parameters. This study provides a comprehensive understanding of rock mass behavior when the widening of any underground opening is carried out.

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