bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of collapse mechanism of a High Speed Railway Tunnel (T341 Tunnel, Turkey)
Authors: Aygar E B , Gokceoglu C 
Published: September 2021

Abstract
Excavation and implementation of tunnel support system of T341 tunnel of Ankara-Sivas High Speed Train Project were completed recently. Throughout the tunnel excavation, serious stability problems occurred both in the entrance portal section and tunnel. The purposes of this study are to explain the failure mechanism and to propose a suitable support system for the section between Km: 341 + 040 - 341 + 114. Tunnel works were interrupted after the collapse, which occurred in a section of approximately 74 m between Km: 341 + 040 - 341 + 114. As a result of the collapse in the tunnel, local settlements emerged on the surface and it was observed that the effects of the collapse on the surface, as well. To surpass the collapsed section, extra reinforcements were performed by grouting taking place both at the surface and inside the tunnel. Afterwards, tunnel excavation was completed in relatively short stages by applying double umbrella system and rigid support system. Consequently, the causes of the failure, excavation and support system design and results of the numerical analyses are discussed.
Evaluation of collapse mechanism and portal interaction of a High-Speed Railway Tunnel (T29 Tunnel, Turkey)
Authors: Aygar E B , Gokceoglu C 
Published: September 2021

Abstract
Within the scope of the Ankara-Istanbul High Speed Train Project, the T29 tunnel was opened to traffic after completing excavation and support implementation. The tunnel was excavated in weak to very weak graphitic schists causing severe face stability problems and deformations on the tunnel supports during excavation stage. In the progress of the excavation stage, a serious face failure occurred at Km: 225 + 784, and the effects of this face failure were observed on the surface. Since the cover thickness is approximately 35 m in this section of the tunnel, it was decided to pass this zone with a cut and cover structure. The portal excavation was carried out from the failure zone, and it was planned to provide stability with the closure of the surface by constructing a cut-and-cover structure immediately afterwards. However, slope failures occurred during the portal excavations. This section was reworked, and it was decided to support this area with a pile system. Consequently, in this study, the reasons for the face failure and slope failures are investigated, and the construction stages are explained and discussed.
Sensitivity analysis of a new model to predict the survival probability of artificial rock blocks upon dynamic impact
Authors: Guccione D E , Buzzi O , Thoeni K , Fityus S , Butcher C , Giacomini A 
Published: September 2021

Abstract
Rockfall fragmentation is a very complex phenomenon that is still poorly understood and modelled. Being able to adequately model fragmentation of impacting blocks, including change of shape, size, and energy after breakage, is essential to be able to predict realistic trajectories and design effective mitigation measures. In order to develop an accurate predictive model for rockfall fragmentation, it is necessary to better understand the fragmentation process and its likely outcomes. A novel model was recently proposed by the authors which can predict the survival probability (SP) of brittle spheres upon impact from the statistical distribution of material parameters, obtained by standard quasi-static tests (Brazilian tests and unconfined compression tests). The survival probability is described as a Weibull function whose two parameters (shape parameter-m-and scale parameter - critical kinetic energy) are predicted by the model. The model is based on theoretically-derived (from Hertzian contact theory) conversion factors used to transform the critical work required to fail disc samples in quasi-static indirect tension into the critical kinetic energy to cause failure of spheres at impact in vertical drop tests. This paper presents a sensitivity analysis on the parameters which influence the prediction of the critical kinetic energy.
Rock joint scale effects in numerical modelling - Hinkley Point C, a case study
Authors: Ogunmakin B A , Koe A , Jean-Philippe M 
Published: September 2021

Abstract
This paper presents the details of the approach to numerical modelling of the subvertical rock slopes resulting from the deep excavations associated with the foundations and basements for Hinkley Point C, Nuclear Power Station, in Somerset, UK. The ground model, which was based on an extensive ground investigation, indicated that the rock mass comprised thinly bedded mudstones and occasional limestones of the Blue Lias Formation. The structural geology of the site consisted of two major faults with five minor faults. These faulting resulted in highly fractured rocks with closely spaced discontinuities with unfavourable orientations and dip angles relative to the slope face. The design methodology for the project included Discrete Element Method (DEM) of numerical modelling using UDEC, a commercial software suitable for modelling fractured rock behaviour. As part of the development of the analytical model, a number of simplifications in terms of modelling, needed to be undertaken to enable development of a series of models that adequately reflected the likely ground conditions during excavation, but that could be run effectively under the usual constraints of a commercial project. One of such key simplifications relates to rock joint spacings. Modelling the rock joints spacings as measured on site in UDEC would result in extremely long computation time. It was necessary to scale up joint spacing in the model without compromising on the accuracy of the results. Series of sensitivity analyses were carried out to assess the effects of joint spacing on the slope stability analysis. From these analyses, an appropriate joint spacing scale up factor was derived. The output from the modelling included assessments of likely displacement of the rock slopes during excavation and as part of the construction works for the basements a programme of extensive monitoring was undertaken to verify the results of the modelling. The paper presents the ground model as interpreted from the ground investigation, the sensitivity analysis undertaken to help develop the approach for the analytical model and the results of the numerical modelling. It then goes on to compare these with the actual ground conditions revealed as excavation was undertaken, and the deformation recorded on the rock slopes during excavation. The paper goes on to present conclusions with respect to the modelling similar rock masses effectively using numerical modelling techniques.
Finite element for Richards’ equation in porous rocks
Authors: Scussiato T , Ferrer A M , Ito W H , de Queiroz P I B 
Published: September 2021

Abstract
The interaction processes of water movement and environment have several aspects important to engineering and geology, which motivate a large amount of research all over the world. As computers with larger capacity become available and affordable, several simplifications used in the past have become meaningless, and nonlinear complex phenomena like unsaturated flow can be processed in affordable machines. The reduction of water flow capacity of filters and drains in embankments due to unsaturated zones, and the environmental problems of remediation of contaminated zones in porous rock masses at the vadose zone are examples of special problems in which advanced modeling should be applied to avoid misleading conclusions or dreadful consequences. The unsaturated flux can also be important in understanding the influence of humidity in the bowing phenomenon in calcitic marbles, since laboratory tests have shown different evolutions of this pathology in partially saturated samples and in completely wet or dry samples. Moreover, this formulation also has important application in building envelope modeling, like in evaporative roofs which enhance thermal comfort in hot weather. To increase the understanding of unsaturated problems, this paper presents a finite element formulation for applications in unsaturated flow in stiff porous media, like sedimentary rocks or concrete. The formulation is based on Richards’ equation for one-dimensional flows and it includes a linear interpolation of suction, as well as an arbitrary implicit parameter.
High stress gradient, critical factor affecting rock burst in the United States mines
Authors: Maleki H 
Published: September 2021

Abstract
To enhance the understanding of seismicity and violent failure mechanics for development of control measures, significant research has been dedicated in South Africa, Europe, USA, China and Australia within the last century. Considering complexity of coal pillar mechanics, the author has used two approaches for enhancing understanding of violent failure in US mines (1) carefully reviewing field measurements from US mines and (2) applying a hybrid statistical-analytical method for identifying critical factors contributing to violent failure of coal measure rocks. These studies reinforce the significance of higher risks where mining in areas of high stress gradients, increasing the potential for sudden failure of near seam strata, depending on geologic and stress conditions. High stress gradient condition is commonly found while mining adjacent to some geologic structures (faults/grabens), multiple seam solid-gob crossings and even occasionally on development where failure of highly stressed roof/floor units triggers seismicity and the failure of marginally stable pillar ribs. The latter mechanism has also been experienced in hard rock mines and shown to be associated with buckling failure. Example of stress conditions from case studies are analyzed in this paper.
Research and assessment of the rock burst hazardous of the Kola Peninsula mineral deposits by seismic-acoustic monitoring data
Authors: Rasskazov M , Rasskazov I , Gladyr A , Tereshkin A , Tsoi D , Rasskazova A 
Published: September 2021

Abstract
The results of geomechanical studies to assess the rock burst hazard at the deposits (Kukisvumchorr and Apatite Circus) of the Kola Peninsula are presented in the article. These results are obtained by special set of technical means, including an automated seismic acoustic rock pressure monitoring system “Prognoz-ADS” and a portable geoacoustic device “Prognoz L” developed at the Mining Institute of the Far Eastern Branch of the Russian Academy of Sciences. Based on the measurement and analysis of the parameters of seismoacoustic events, reflecting the geomechanical processes in the mined rock mass, maps of seismoacoustic activity combined with 3D mining and geological models of mines were developed. Based on the analysis of the spectral parameters of the signals, it was concluded that the use of the developed software and hardware complex is promising for predicting dynamic phenomena in the rock massif. The rock burst hazard can be assessed by the measuring complexes at these deposits; necessary safety measures can be taken for decrease of geodynamic risk.
Experimental investigation of double scroll cutting pattern by using button cutting tool of raise boring machines
Authors: Copur H , Shaterpour-Mamaghani A , Gumus A , Tumac D , Balci C , Kocbay A , Erdogan T , Avunduk E 
Published: September 2021

Abstract
Full-scale linear cutting test is one the most preferred and reliable methods for performance prediction of mechanical miners. Raise Boring Machines (RBMs) are one of these mechanical miners which are commonly used for drilling / excavation of shafts for different purposes in mining and tunneling projects. This study aims at investigating experimentally double spiral (scroll) cutting pattern in raise boring machine. Full-scale linear cutting tests are performed by using button (kerf) cutting tool. The tests are performed at line spacing of 25 mm and varying depths of cut per revolution by using two hard rocks (diabase and granodiorite) that were obtained from the Yusufeli Dam and HEPP project site. The average and maximum normal, rolling and side forces; specific energy; yield; and coarseness index are measured in each cut. The study indicates that optimum ratio of line spacing to depth of cut per revolution are obtained as 8.3 and 4.2 for diabase and granodiorite samples, respectively.
Failure Analysis of an Intersection under Squeezing Rock Conditions
Authors: Ozturk H , Foo B 
Published: September 2021

Abstract
The development of Turkey’s deepest coal mine is currently underway to the proposed depth of 1200 meters (m) below surface at the Soma Coal Basin. An 11 m intersection forming an access way from one of the main declines was excavated at approximately 900 m below surface collapse within hours of completion even after being heavily supported by TH34 and cable bolts. It was discovered during the excavation failure investigation and rehabilitation work that the intersection was excavated below a water bearing stratification and faulted zone of the coal seam. The failure analyses concluded that the failure was contributed by a number of factors, mainly the overburden pressure of the overlying material along with the inrush of high-pressured groundwater with the very poor rock mass surrounding the excavation. This study investigates the possible reasons of the failure, numerical modelling of the intersection and alternative support suggestions for such squeezing rock conditions.
Experimental study of ore lifting efficiency with mixture of bentonite suspension and sand as a carrier material for deep sea mining
Authors: Orita K , Tani K , Suzuki A , Kosho T 
Published: September 2021

Abstract
Carrier material (mixture of viscous fluid and fine particles, CM) circulation system was proposed to lift up deep sea mineral resources. This study focuses on appropriate mixing proportions of CM for lifting up heavier and coarser ores. The results of model tests of ore lifting demonstrated that CMs of mixture of water, bentonite and sand particles could lift up heavier and coarser ores than those lifted in the conventional system by far lower vertical flow velocities. Moreover, ore lifting efficiencies were found to be improved by restricting movements of CMs around ores via the wall of the vertical pipe.
An approach to estimate coal pillar strength
Authors: Sharipov A S , Adoko A C 
Published: September 2021

Abstract
In this paper, a probabilistic design chart for coal pillar based on South African coal mine experience is proposed as a tool capable of estimating the pillar strength. A methodology based on the logistic regression is employed to identify failed and intact pillars with their corresponding probabilities of occurrence. The input parameters used for pillar design include the mine depth, pillar width, bord width, height of mining excavation and panel width. The results showed that 84.6% of the pillars, including stable and failed categories, were correctly classified. In addition, the probability associated with the pillar conditions was determined and plotted in form of a pillar strength graph. The results were in good agreement with the field data and existing studies. One of the merits of the current study is that the probability of having a coal pillar intact or failed can be easily determined. This is particularly useful for design purposes since a series of uncertainties are usually involved in collecting the rock mass parameters. It is concluded that the results of this study could improve the empirical design of coal pillars.
Implications of in-situ stress measurement in mining engineering
Authors: Li Peng , Wu Yunquan , Cai Meifeng 
Published: September 2021

Abstract
Knowledge of the in-situ stress conditions in mining areas is very necessary for scientific mining design and effective disaster control measures. The object of this article is to systematically introduce the in-situ stress measurement method and its implications in mining engineering, including mining design optimization, rockburst mechanism and prediction, stability control of surrounding rock, fault stability assessment, exploration and development of coalbed methane, coal and gas outburst prediction, evaluation of water inrush from coal floor, and high-stress rock breaking. The research results are of great significance to realize the safe, economic, and efficient recovery of mineral resources.
Monitoring of rock stress change using instrumented rebar rock bolts
Authors: Mai W , Janiszewski M , Uotinen L , Mishra R , Rinne M 
Published: September 2021

Abstract
Rock stress is causing unwanted deformations of deep underground spaces. Large deformations increase the risk of failure. The underground excavation causes rock stress changes in the surrounding rock mass, and the resulting deformations can be measured. In this paper, we present a method to monitor stress changes in the rock mass using rebar rock bolts instrumented with strain gauges to track the stress within the bolt. Next to that, we describe in-situ testing of this method using heating-induced stress in a natural underground environment. The heating experiment aims to create stress changes using rope heaters inserted into the rock mass and located symmetrically around a single instrumented rock bolt. The heat flux induced to the rock mass leads to volume expansion. The restricted thermal expansion causes an increase in the internal rock stress conditions. These conditions create a strain that can be measured and back-calculated as the rock stress change. The instrumented rock bolt and testing setup were installed in the Underground Research Laboratory located in a granitic rock below the Aalto University campus. The single bolt experiment demonstrates how instrumented rock bolts could monitor the changes in the rock mass stress state. The system can be used as a part of a real-time rock stress monitoring system in mining and rock engineering projects. The final part of the paper describes how this monitoring system can positively affect geotechnical risk management and increase the overall safety of underground construction.
High alpine geotechnical real time monitoring and early warning at a large imminent rock slope failure (Hochvogel, GER/AUT)
Authors: Leinauer J , Jacobs B , Krautblatter M 
Published: September 2021

Abstract
Monitoring and early warning systems based on process dynamics gain importance to cope with an increasing number of alpine hazards. The imminent Hochvogel rock slope failure (up to ca. 260,000 m3) is paradigmatic of natural carbonate slope failure dynamics and a benchmark site for developing an effective monitoring and early warning system. The analysis of process dynamics shows constant movement rates (12 mm/a) over the last 3 years but also a response of specific cracks to heavy precipitation events resulting in factor 5 higher movement rates during wet periods. Here, we show valuable lessons learnt during the development of a reliable monitoring system under challenging environmental conditions. The insights into pre-failure slope dynamics acquired at the Hochvogel will help to detect precursors of a final failure and to warn early.
Rock mechanics and engineering for the Klein Matterhorn glacier paradise (Zermatt, Switzerland)
Authors: Dalban P , Haas R , Lauber M , Naterop D 
Published: September 2021

Abstract
The Alpin X project is carried out by the Zermatt Bergbahnen AG and aims at establishing a touristic link between Zermatt in Switzerland and Cervinia in Italy while facilitating access to the top of the Klein Matterhorn. This very challenging project is based on the construction of two new modern cableways joining each other at adjacent arrival stations founded in the 50-70° steep west face of the Klein Matterhorn, at 3’820.5 m a.s.l. Due to the steepness of the slope, construction works require extensive excavation and stabilization of the serpentinite bedrock and consequently to address various problematics related to superficial and shallow rock instabilities inside and outside the construction area. Moreover, the predominance of permafrost conditions required to adapt the techniques for the execution. While the first cableway from the north-side has been operational since winter 2018/2019, the second from the south is still under construction and will open in winter 2021/2022.
Looking inside TBM parameters: feedback from the Tunnel 4 case study, Angat Water Transmission Improvement Project (Philippines)
Authors: Bianchi G W 
Published: September 2021

Abstract
The use of TBMs in the tunnel industry has undergone a continuous growth over the last years, with application in ever expanding ranges of geotechnical conditions. Nevertheless, the feedback from completed projects with respect to the use of machine data for assessing geotechnical conditions are not common: there are only a few attempts to correlate machine data with geotechnical conditions during excavation and in most cases the use of machine data is related to assessment of TBM performance for prediction of advance rate. The analysis of TBM parameters may represent an interesting tool for monitoring of geotechnical conditions at the tunnel face and early detection of adverse face conditions. This work presents the feedback from the Tunnel 4, a 6.4 km long water transfer tunnel excavated by double shield TBM in the Philippines. The machine data have been analysed for identification of most sensitive parameters to geomechanical properties of the rock mass. In this respect, the use of specific-excavation parameters provides best results for assessing geotechnical conditions during excavation. Specific energy and Field Penetration Index displayed a good correlation with RMR values. The combined use of Net Advance Rate and Drillability Index allows to highlight how unstable face conditions and / or tough rock can influence the TBM advance.
A Novel Approach for Design and Simulation of Equivalent Continuum Model of Lattice Structures Used in Tunnels and Caverns
Authors: Rishabh Tiwari 
Published: September 2021

AbstractDeveloping a continuum model of a lattice structure means expressing a complicated structure into a simpler one, and this is done by determining equivalent stiffness of the original structure, which can further be used to transform into desired simpler geometry for multiple benefits. Objective of this paper is to find a reliable method for determination of equivalent stiffness of lattice girder, comparing all the techniques suggested by various researchers. In present work the actual lattice girder structures and their equivalents were analysed using Finite Element Method tool Strand7. The primary focus is on lattice girder, which is a primary rock support system employed in tunnels and caverns. The equivalent stiffness so obtained is used as input parameter in numerical analysis tool STRAND7 for analysis of equivalent lattice beam. The maximum deflection and bending stress at centre of equivalent lattice beam were calculated and compared. In an attempt to develop a more accurate equivalent beam modela novel approachwhich is modification of the Method-B has been developed by authors. This Noval approach is the most convenient approach to develop an equivalent section with an extremely uncompromised representation of stress development and deformation characteristic. In this approach, the focus was made on the physical resemblance of a proposed equivalent beam with the actual lattice girder, leading us to adopt a beam of I-cross-section. This approach yielded similar stress and deflections in the equivalent beam as that of the actual lattice girder.