ISRM 2023 - PUBLICATIONS

T01: Challenging rock engineering projectsJoachim MICHAEL (1), Lisa WILFING (2)1: Prof. Quick und Kollegen - Ingenieure und Geologen GmbH, Germany; 2: Boley Geotechnik GmbH, GermanyComplex tasks to evaluate the feasibility of two railway tunnel variants in terms of tunnel constructionThe expansion/new construction of the railway line "Hanau-Würzburg/Fulda-Erfurt" is one of 13 infrastructural projects of the Deutsche Bahn AG that are to be implemented with high political priority. The new DB-Line Gelnhausen-Fulda is a sub-project of this infrastructure project with a section of approximately 42 km (variant IV) respectively 48 km (variant VII) and hence, the planned construction of up to 80 percent of each variant in a tunnel. From a geotechnical point of view, two route variants are examined in detail regarding feasibility of the tunnel construction and taking hydrogeological and natural aspects into account. Both variants have a very high impact and require very different requirements on the planning and selection of suitable tunneling methods. In this article the relevant geotechnical, geophysical and rock-mechanical investigations and findings are presented in detail as the basis of the decision-making process in finding the most economical and operational suitable route variant. | Tunnel, Geotechnical Investigation, complex ground conditions, Building information modeling
T01: Challenging rock engineering projectsAfshin ARABZADEH, Xavier DONTIGNY, Marianne DEBELNouvLR, CanadaThe effect of TBM tunneling on the surface and underground deformations under Montreal-Trudeau international airport (YUL) runwayThe Réseau Express Métropolitan (REM) is a light rail system that spans 67 km and will link the Pierre-Elliot-Trudeau International Airport to the greater Montreal area. As part of the system, a 3 km tunnel starting at the Marie-Curie station is being built by a TBM machine with a diameter of 7.37 m to join the airport station. The tunnel alignment passes under airport runway 06L/24R. To estimate the effects of TBM tunneling on surface subsidence under runway 06L/24R, a 2-D numerical analysis was conducted using the FLAC-2D code. Moreover, to monitor the surface and ground movements by TBM tunneling, geotechnical instruments as well as radar imagery InSAR system were installed along the tunnel alignment. The numerical modelling results show that the induced ground surface settlements for runway 06L/24R caused by TBM tunneling is negligible and the results obtained from geotechnical instruments were validated against the numerical analysis findings. | TBM tunneling, numerical analysis, geotechnical instruments, surface subsidence, underground movement
T01: Challenging rock engineering projectsTanja SATTLER (1,2), Kurosch THURO (2)1: Baugeologisches Büro Bauer GmbH, Germany; 2: Technical University of Munich (TUM), GermanyAdvancements in drillability prediction for conventional hard rock drill and blast tunnelling – implementing automation into the equationWith tunnelling projects being part of critical infrastructural development, it is of uppermost importance to schedule the construction for an on-time delivery. Specifically, a reliable drillability prediction is indispensable to forecast advancement rates adequately. With the drillability being a very complex entity, predicting advancement rates is challenging, potentially leading to extensive additional cost and operational delays. Based on a case study from an Austrian tunnelling project, various influencing factors were examined. Comparing predicted with actual drilling velocities, it was shown that the actual drilling rates remained behind the expectations by about 20 %. The analysis clearly shows that the geological conditions are not responsible for these shortcomings, but the working process and the machine parameters including the degree of automation being significant factors of influence. | drillability, penetration prediction, drilling automation, collaring, drill and blast tunnelling
T01: Challenging rock engineering projectsRajanish RANJAN, Girish KALITANEEPCO, IndiaChallenges faced and mitigation measures adopted in construction of head race tunnel of Kameng hydro electric project (600 MW), Arunachal Pradesh, IndiaKameng Hydro Electric project (4x150MW), a ROR scheme was constructed by North Eastern Electric Power Corporation Ltd in the West Kameng District of Arunachal Pradesh, India. This project lies in the Lesser Himalaya consisting of Precambrian and Gondwana rock formations. A 14.5 km long tunnel was constructed to convey water from Bichom to Kimi for 600 MW of power generation. This paper deals with the challenges faced during tunnel boring in tectonically disturbed Himalayan terrain and the mitigation measures adopted in overcoming these geological challenges. The challenges comprised cavity formation, blow out, Squeezing, high seepage and very weak rockmass with high rock cover. The mitigation measures adopted to overcome these challenges included fore-poling, umbrella/canopy with channel/joist and chemical/cement grouting etc. After overcoming all these tunnelling challenges, the boring of HRT was successfully completed in March’2015. | Mitigation, DRESS, Himalaya, Grouting, Squeezing, Weak rockmass
T01: Challenging rock engineering projectsGuangming YU (1), Penghui ZHANG (1), Qimeng SHI (1), Guanwen LIANG (1), Jun LEI (2), Xinwang YANG (1), Lijun KUANG (2), Daning WANG (3), Mikhail D. KOVALENKO (4), Irina V. MENSHOVA (5), Alexander P. KERZHAEV (6)1: Civil engineering College, School of Civil Eengineering Qingdao University of Technology; 2: China Construction Fifth Engineering Division Corp.,ltd; 3: regio iT gesellschaft für informationstechnologie mbh; 4: Institute of Applied Mechanics, Russian Academy of Sciences; 5: Institute of Earthquake Prediction Theory and Mathematical Geophysics; 6: Bauman Moscow State Technical UniversityThe Synergetic Evaluation Model of Machine-Rock in TBM-EPB Shield Construction and its computer realizationThis paper explores the influencing factors, mechanical mechanism and evaluation model of "machine-rock" cooperative mapping in dual-mode shield (TBM-EPB) tunnel construction, and scientifically determines the order parameters of artificial and natural interaction system evolution in dual-mode shield (TBM-EPB) tunnel construction by means of mechanics and Synergetics, and establishes a "machine-rock" cooperative mapping evaluation model for dual-mode shield (TBM-EPB) tunnel construction. The "machine-rock" cooperative mapping of dual-mode shield (TBM-EPB) tunnel construction is evaluated by computer, and verified by a typical case of efficient and safe construction of dual-mode shield (TBM-EPB) tunnel between Liuxiandong Station and Baimang Station of Shenzhen Metro Line 13. Finally, the future development trend and key technologies of dual-mode shield (TBM-EPB) tunnel construction are predicted, and the future research trends. The results of this paper have important guiding significance for the toughening construction of underground tunnel and its cooperative coexistence with the environment. | dual mode shield (TBM-EPB), tunnel construction, "machine-rock" interaction, collaborative mapping, evaluation
T01: Challenging rock engineering projectsVerya NASRIAECOM, New York, United States of AmericaDesign and Construction of the Montreal Largest Transit SystemOnce completed, the Montreal Réseau Express Métropolitain (REM) will be the fourth largest automated transportation system in the world. The REM represents the largest transportation infrastructure in the region since the Montreal metro inaugurated in 1966. The proposed solution fosters environmentally sustainable transportation and represents a construction cost of approximately 7.0 billion Canadian dollars. The project consists of 67 km over four branches of twin track and includes 26 stations with 3 underground stations in downtown Montreal. One of the underground stations was built using the NATM method with thin permanent shotcrete initial and final liners separated by a sprayed on waterproofing membrane. The project also includes the rehabilitation and enlargement of the 100-year-old double track Mont Royal Tunnel which is about 5 km long. The REM also consists of 3.6 km new TBM tunnel connecting downtown to the Montreal International Airport through saturated soft ground and karstic rock. | TBM Tunnel, NATM Station, Deep Shaft, Tunnel Rehabilitation, Shotcrete Permanent Liner
T01: Challenging rock engineering projectsManuel BODE (1), Magdalena SALLINGER (1), Paolo ZANANDREA (2), Thomas MARCHER (1)1: SKAVA Consulting ZT GmbH, Austria; 2: Ingenieurgemeinschaft GMK, ItalyHard Rock Caverns with low overburden in urban environment – a case studyThe design and the construction of underground caverns with low overburden in an urban environment is a sophisticated task. The project of an urban parking garage, which is built within a large span cavern construction is presented. Due to its low overburden, combined with the dominating behaviour of the jointed rock mass, there was a need of complex modelling techniques and considerations in design. The contribution gives an overview over the project, including the morphology, the ground investigation and classification and special risk scenarios. It also provides an insight in the design of the excavation process, the support measures and the accompanying monitoring process. | Cavern, urban environment, low overburden, analysis and design, jointed rock
T01: Challenging rock engineering projectsAnton KALTENBÖCK, Martin PURUCKER, Bernhard STACHERLGeoconsult ZT GmbH, Puch bei Hallein, AustriaThe Blue Line Jerusalem LRT Underground Section – Public Transport in a challenging Project environmentThe 2 km long Blue Line Underground Section is part of a 20 km long LRT line currently being developed as part of the Jerusalem Mass Transit Master Plan. The Underground Section of the Blue Line is characterized by narrow streets, limited right of way, steep gradients, small alignment radii turns and crossings with other LRT lines. The geological conditions feature different formations of limestone and dolomite. Karst is a known frequent phenomenon in the Jerusalem region which must be considered in the design and construction process. This publication describes the key criteria to be addressed in the design, such as the overall design approach for the large span station tunnels, geological risks especially in relation to karst, the impact on existing buildings and the insertion of the underground stations in a highly sensitive urban environment with very limited available space. | Tunneling, Underground, Karst, NATM, Monitoring
T01: Challenging rock engineering projectsGerhard GOBIET, Gernot NIPITSCH, Oliver Kai WAGNERÖBB Infrastruktur AG, AustriaSemmering Base Tunnel (SBT) - current state of the projectThe Semmering Base Tunnel (SBT) is about 27.3 km long and driven from the portal at Gloggnitz and three intermediate construction accesses in Göstritz, Fröschnitzgraben and Grautschenhof. The main components of the tunnel system are two single-track tunnels, cross passages at a maximum distance of 500 m and an emergency station in the middle tunnel section, with two ventilation shafts with a depth of approx. 400 m in case of an incident. For reasons concerning organization, timetable and topography, the tunnel is divided into four construction contracts. Construction work of the tunnels started in 2014. By autumn 2023 98% of the tunnel excavation is completed. In the landfill site in Longsgraben, where most of the excavated material is deposited, recultivation started. The presentation highlights the current state of the project, present achievements, and an outlook to further works. | Semmering Base Tunnel, general scope, state of project, tunnelling
T01: Challenging rock engineering projectsHarald EGGER (1), Marco Giuseppe FODERÀ (1), Gianluca LIUZZI (1), Antonio SPAZIANI (1), Antonio VOZA (1), Daniela BOLDINI (2)1: Galleria di Base del Brennero – Brenner Basistunnel BBT-SE; 2: Sapienza University of Rome, ItalyPerformance of different diameter Double Shield TBMs: experiences from the excavation of exploratory tunnel and main tubes of the Italian lot Mules 2-3 – Brenner Base TunnelThe Brenner Base Tunnel is a 64 km long underground railway connection under construction between Italy and Austria. The project mainly consists of two main one-track tunnels and a central exploratory tunnel 12 m below them. Considering that the three tunnels intersected the same rock masses and fault zones, the paper analyses the scale factor displayed by selected machine parameters in relation to the tunnel diameter, TBM characteristics and rock mass conditions. Final considerations about the performance of the three TBMs, also in the context of comparable case-histories, are addressed. | Brenner Base Tunnel (BBT), Double Shield TBM (DS-TBM), Exploratory Tunnel (ET), Main Tunnels (MT), Key Performance Indicators (KPI), scale factor
T01: Challenging rock engineering projectsVojkan JOVIČIĆ (1), Boštjan VOLK (2), Gregor VESEL (2), Jože RATEJ (2), Markus SCHMIDT (3)1: Faculty of Civil and Geodetic Engineering, University of Ljubljana, Slovenia; 2: IRGO, Slovenia; 3: Boratec, GermanyTunnelling in Slovenian Dinaric karst: challenges and solutionsSlovenian Dinaric Karst is an extensive karst area, 800 km long and up to 150 km wide, which is distinguished by large, closed planes, and variety of relief forms, deep caves, underground rivers, and karst springs. The main challenge for the construction of new Divača-Koper railway line that runs through Slovenian Dinaric Karst is the construction of two seven kilometers long tunnels T1 and T2. Due to scarcity of water resources in the area adequate measures for tunnel construction had to be developed to ensure the sustainability of water resources in the long term. The paper presents experience that was assembled in detection, evaluation and categorization of karstic phenomena that was encountered during the construction of tunnel T1. The temporary and final remedial measures of typical karstic features are presented in the paper highlighting the stability, functionality, and sustainability issues, which were subject to design evaluations and solutions. | tunneling, karst features, remedial measures, sustainability of water resources
T01: Challenging rock engineering projectsKarsten THERMANN (1), Raja Bhai SHILPAKAR (2), Bibash PARAJULI (3), Eirinaios CHRISTAKIS (1)1: Tractebel Engineering GmbH, Germany; 2: Tanahu Hydropower Ltd, NEA, Nepal; 3: PowerChina Chengdu Engineering Co. Ltd, ChinaDifficult Ground Conditions demand for an Observational Approach for a Powerhouse Cavern in the HimalayasThe powerhouse cavern excavation for Tanahu Hydropower Project (140MW), in Nepal, was successfully completed in July 2022. The site is geologically located in the Lesser Himalayan Zone. During cavern excavation, moderately to highly foliated Slate with phyllitic Slate intercalations and localised sheared zones were encountered. To cope with difficult ground conditions, the design of rock support was not only based on 3D-modelling but rather adopted an observational approach. Thus, during excavation a thorough monitoring system was implemented consisting of multi-point borehole extensometers, load cells, convergence stations and piezometers. Data collection and evaluation of results were conducted on a daily basis during the whole excavation process. Aiming to mitigate occurring deformations during the excavation stage, the rock support measures were modified accordingly. Furthermore, to control overstressing, loads from pre-stressed double-corrosion protected anchors required stress release. The timely response to monitoring results was of paramount importance for the successful excavation of the powerhouse cavern. | observational method, powerhouse cavern, pre-stressed anchors, instrumentation, phyllitic Slates
T01: Challenging rock engineering projectsJohannes JESSEN (1), Jochen FILLIBECK (1), Florian ZAHLER (2), Raphael ZUBER (2)1: Technical University of Munich, Munich, Germany; 2: Weilheim State Building Authority, Weilheim, GermanyPU grouting and sealing measures on the Kramer TunnelThe Kramer Tunnel in the north of Garmisch-Partenkirchen is designed as a single-tube road tunnel with two-way traffic. The tunnel was excavated using NATM. The 3,600 m long tunnel is divided into a pressure-relieved (drained) section and a waterproof (sealed) section, which can withstand pressures of up to 5 bar. Four shotcrete bulkheads were installed to separate the sealed section (rock-slide area) from the drained section. Additionally, PU grouting was employed around the bulkheads to reduce the longitudinal water flow along the main and exploratory tunnels. This article reveals how the radial grout curtains were executed within limestone-marl alternations. Taking the geological conditions into consideration, the success and quality of the grouting work was monitored by water pressure tests and by quantitatively evaluating the grouting records. Construction details concerning the chemical injection material, the grouting equipment and the break-off criteria are discussed. | chemical grouting, grout curtain, bulkhead, break-off criteria
T01: Challenging rock engineering projectsAndrew SHIELS (1), Marc MPOYO (2), David BECK (3), Sevda DEHKHODA (4)1: Glencore Copper, Brisbane, Australia; 2: Kamoto Copper Company, Kolwezi, DRC; 3: Beck Engineering Pty Ltd, Sydney, Australia; 4: Beck Engineering Pty Ltd, Brisbane, AustraliaSimulating global deformation and assuring ongoing stability in a complex multi lode room and pillar mineA widespread series of pillar failures occurred at the Kamoto Copper Mine in the early 1990’s. Access to the affected areas was lost and an extended period of mine closure followed. To constrain interaction between the past failure and future work areas, the current mine required careful considerations and interactions with the failed zones, and a barrier pillar has been retained to protect the future work areas from effects of the past failure. A system of access pillars and stabilization pillars and staging of extraction works to shape deformation, manage stress, and allow a sufficient degree of control over stability has been implemented. Mine stability is maintained through an ongoing process of engineering design, simulation, observation, and analysis for a mine with a complex system of pillars, which is described in this paper. | Room and pillar, global stability, pillar failure, observational programme
T01: Challenging rock engineering projectsSailesh ADHIKARI (1,2), Krishna Kanta PANTHI (1), Chhatra Bahadur BASNET (2)1: Norwegian University of Science and Technology, Norway; 2: Pashchimanchal Campus, Tribhuvan University, NepalStability issues associated with the construction of underground caverns of Super Dordi Hydropower Project, NepalThe rock mass is heterogeneous and makes underground space construction a challenge to engineers. The rock formation, mineralogical composition, degree of schistosity, and weathering, are the major factors that determine the stability condition and rock support requirements. This manuscript deals with the stability situation of the underground settling basin caverns of Super Dordi Hydropower Project (SDHP) in Lamjung district of Nepal which is located at the lower boundary of the Higher Himalayan rock formation. The two parallel underground settling basins are 120m long and have an approximate cross-sectional area of 113 sq. m. The manuscript further discusses geological and rock mass quality conditions and evaluates the stability of the underground settling basins using 2D numerical modeling. The outcomes of the analysis presented in the manuscript have been helpful for the optimization of applied rock support. | Underground Space, Rock Support, Settling Basin Caverns, Super Dordi Hydropower
T01: Challenging rock engineering projectsMario HEIN (1), Zafer EKICI (2), Christine PEINTNER (2), Robert HOLZER (1), Thomas HOFMANN (3)1: Geoconsult Wien ZT GmbH, Austria; 2: IGT Geotechnik und Tunnelbau, Austria; 3: ÖBB Infrastruktur AG, PL Semmering Basistunnel, AustriaSemmering Base Tunnel – Geotechnical challenges at crossing a fault system in combination with high water pressureThe Semmering Base Tunnel (SBT), one of the major infrastructure projects in Europe is part of the Baltic-Adriatic railway corridor and connects the two federal states of Lower Austria and Styria. Due to its total length of 27.3 km and complex rock mass conditions, the project is divided into 3 construction lots. The eastern construction lot SBT 1.1 Gloggnitz Tunnel crosses major fault zones adjacent to water-bearing carbonatic rocks (Grassberg), with a potentially high water inflow in combination with high water pressure. Crossing the fault system north of the Grassberg is one of the biggest challenges of lot SBT 1.1, due to the poor rockmass quality within the fault system and 10 bar water pressure within the Grassberg. Systematic probe drillings indicated a complex sequencing of geological units at the transition from the fault zone into the water-bearing Grassberg unit and required a modification of the original design approach. | Semmering Base Tunnel, grouting, monitoring, high water pressure, high permeability
T01: Challenging rock engineering projectsWalter WITTKE, Martin WITTKE, Patricia WITTKE-GATTERMANN, Bettina WITTKE-SCHMITTWBI GmbH, Germany50 km of Tunnels in Inner-City Areas – Rock Mechanics and Tunneling Issues in Connection with the large-scale Railway Project Stuttgart 21 – A Success StoryFor the large scale railway project Stuttgart 21 more than 50 km of tunnels were constructed in the city of Stuttgart. Currently, the tunneling works at the new airport station are carried out, while the other tunnels have already been finalized. In connection with the project, numerous challenges of rock mechanics and tunneling have been solved from the design point of view as well as from the construction point of view. These are – amongst others – 17 km of tunnels in anhydrite, full face excavation of large cross sections with A > 200 m², compensation grouting, TBM tunneling in sedimentary rock, various underpinning measures and the excavation of complicated large shafts and tunnel structures in geologically pre-stressed clay stones of the Jurassic. The paper gives an overview on the project and presents some of the highlights of rock mechanics. | Tunneling, Rock Mechanics, Swelling Rock, Large Cross Sections, Underpinning, AJRM
T01: Challenging rock engineering projectsLineu Azuaga AYRES DA SILVA (1), Guilherme Gianotti de ANDRADE (1), Anna Luiza Marques AYRES DA SILVA (1), Fábio ZATZ (2)1: University of São Paulo, Brazil; 2: Ayres da Silva e AssociadosTheory and practice in the boulders and rock blocks blasting in urban areas applied to civil engineering activitiesBlocks of rock are large fragments of the bedrock that have not suffered a strong erosive process and have remained in the soil horizons. They can be oval shaped, or nearly spherical. The calculation for blasting is different, as the volume between these blocks varies, and so does the number of holes required. Thus, a calculation method (Ayres da Silva, A. & Gianotti de Andrade, G. Method) was developed for the oval-shaped rock blocks. Finally, in the blasting of blocks using explosives, it is necessary to find what is the block’s volume to be blasted, because this value is fundamental to obtaining a safe amount of explosives needed for a given specific charge. | Boulders, Boulder blast, Rock block blast, Boulder blast design
T01: Challenging rock engineering projectsLineu Azuaga AYRES DA SILVA (1), Anna Luiza Marques AYRES DA SILVA (1), Guilherme Gianotti de ANDRADE (1), Geronimo Lima RODRIGUES (2)1: University of São Paulo, Brazil; 2: Telar Engenharia e Comércio S.A.Design of controlled rock blasting for tunneling and tunnel portalsToday there is a high demand for transport tunnels in Brazil, where the lack of logistical infrastructure is highlighted by the crowding of vehicles on highways and the congestion of trains on existing networks. The solution is overcoming the topographical relief complexities in urban centers and railway networks. This article deals with one of the tools for solving these problems: the fire plan for controlled rock blasting when opening tunnels and their portals, especially when the work of art is built under restricted conditions; geographic location, rock mass structural and mechanical characteristics, stress states arising from depth or induction from previously existing structures, interference with other transport routes, etc. in addition to all aspects inherent to blasting, such as vibration propagation, explosive force, and other parameters to be considered in its application. It should be noted, in this dimensioning, the use, among others, of the Line Drilling technique. | Tunnel, Rock blasting, Line Drilling, Tunnel portal
T01: Challenging rock engineering projectsStefan SKUK, Harald EGGER, Emanuele BARNABEI, Umberto Marco CONTI, Giuseppe FODERÀ, Gianluca LIUZZI, Gianluca MAGGIO, Davide RENGHI, Antonio SPAZIANI, Antonio VOZABBT Brenner Base Tunnel, ItalyBrenner Base Tunnel: three DS-TBMs excavating in parallel under the Alps in Italy – Findings, difficulties and achievements from a geological-geotechnical point of viewThe Brenner Base Tunnel is a railway connection running beneath the Italian and Austrian Alps for 64 km under high overburdens. In the Italian lot Mules 2-3 a 14 km long stretch of the Exploratory Tunnel has been completed by a DS-TBM with a diameter of 6.85 m and two twin DS-TBMs are currently excavating the Main Tunnels, which are of equal length but have a diameter of 10.71 m. The geological context consists of metamorphic geological units ranging from gneiss, micaschists, phyllites to marbles and intercalations of evaporitic units. About 21 significant fault zones were crossed. Due to different geological factors four standstills occurred in the Exploratory Tunnel, six in the western and two in the eastern Main Tunnels. In order to early detect and manage these critical zones, an accurate geological forecast, advance explorations, geological documentation and a continuous analysis of the machine and monitoring data are required. | Brenner Base Tunnel, Double Shield Tunnel Boring Machine (DS-TBM), Exploratory Tunnel (ET), Main tunnels (MT-W, MT-E), High Overburden, Geological documentation
T01: Challenging rock engineering projectsOskar Leonard VAN DER WEIJ (1), Daniele MARTINELLI (2)1: Kalliosuunnittelu Oy Rockplan Ltd, Finland; 2: Politecnico di Torino, Torino, ItalyExtensive sensitivity analysis of the Kivenlahti metro center using DEMThe Kivenlahti metro center is a combined residential and commercial building complex designed on top of a metro station in Espoo, Finland. Rock mechanical modelling was carried out using 3DEC to ensure the integrity of the metro station. A detailed sensitivity analysis was conducted consisting of simulating the effects of reduced horizontal in-situ stress, increased loading and weaker rock mass. Whilst the base case scenario confirmed that the proposed design should not lead to critical deformations within the metro station, the results of the sensitivity analysis indicated vulnerable locations if the loading is increased from the current design. An in-situ stress significantly lower than expected could lead to critical deformations within the metro station. Whilst the sensitivity analysis was conducted using extreme values, it successfully demonstrated areas for concern and thus aided in designing measures for mitigating the risks for the metro station. | DEM, 3DEC, sensitivity analysis, metro station
T01: Challenging rock engineering projectsLorenzo BATOCCHIONI, Valeria GONZALEZ RODRIGUEZ, Salvatore MILIZIANOSapienza University of Rome, ItalySoil-structure interaction of preliminary deformable lining for conventional tunnel in squeezing conditions using HiDSte elementsThe construction of deep tunnels is continuously increasing due to both economic and environmental reasons. High cover and poor geotechnical ground make the construction of tunnels difficult (squeezing conditions). Due to the high loads transmitted by the ground, the preliminary lining can be rarely designed following the so-called resistance principle. The state of the art suggests approaching the lining design by allowing the development of the necessary convergences to adequately reduce the rock load (yielding principle). In this paper, a new steel element (HiDSte), yet to be employed in real tunnel works, is described. The behaviour of the lining made of steel ribs along the HiDSte is illustrated through 2D numerical analyses. The numerical results allowed the evaluation of the peculiar way soil and lining interact and, more in general, the ability of the yielding lining to reduce the in-situ stress level undergone by the lining. | Conventional tunnelling, squeezing conditions, yielding principle, preliminary lining with elastoplastic elements, soil-structure interaction
T01: Challenging rock engineering projectsPrabhat Kumar MANDAL, Arka Jyoti DAS, Ranjan KUMAR, Subhashish TEWARI, Rana BHATTACHARJEE, Awanindra Pratap SINGHCSIR-Central Institute of Mining and Fuel Research, Dhanbad, IndiaDesign of mechanized underground extraction of deep-seated coal seam by continuous miner technology under massive strata and high in-situ stressA mechanised extraction methodology by continuous miner technology is designed for a deep-seated coal seam under massive strata and high in-situ stress conditions by analyzing the stability of rock mass and the rock burst potential through numerical simulation and field investigation. The coal seam having a horizontal-to-vertical in-situ stress ratio of 2.31, is overlaid by the massive sandstone strata and dolerite sill. 3-D numerical simulation is performed to evaluate the stability of rock mass and accumulation of elastic and plastic energy vis-à-vis strain burst index during different stages of the extraction. The energy-based safety factor approach is applied to identify the failed rock mass in the working places to design the support systems to minimise the failure of surrounding rock mass and the rock burst phenomenon. This paper would help the researchers to extract the highly stressed coal seam under massive strata safely and efficiently. | Rock burst, strain energy, massive strata, support design, in-situ stress, side spalling
T01: Challenging rock engineering projectsShikang QIN (1), Chen XU (2,3), Xichen LI (4), Yabin HUANG (5), Qing YAO (2)1: College of Civil Engineering, Tongji University, Shanghai, China; 2: Institute of Rock Mechanics, Ningbo University, People's Republic of China; 3: Ningbo Key Laboratory of Energy Geostructure, Ningbo, China; 4: Shanghai Giant Energy Technology Co., Ltd., Shanghai, China; 5: The 4th Construction Co. Ltd. of China 15th Corporation, People's Republic of ChinaCollapse mechanism and treatment technology of large-span soft rock highway tunnelTunnel collapse seriously affects the security of the constructers and delays the engineering schedule. Based on the Liangwangshan Tunnel project located in western China, the collapse mechanism of large-span soft rock tunnel under loose load was revealed by theoretical calculation, field measurement and numerical simulation. The low strength-stress ratio of the unconsolidated fragment rock mass leads to a very high loose pressure. The measured stresses of the arch have exceeded its strength, which indicates that the arch is less secure. The FEM results show that I18 steel arch is incapable of resisting ground pressure in this project. Besides, a segmented and graded treatment technique was proposed to deal with tunnel collapse, and the tunnel deformation was successfully controlled. The monitoring data showed that the tunnel was stable after treatment, which shows that the segmented and graded treatment technique was successful and effective. | large-span tunnel, soft rock tunnel, in-situ monitoring, collapse mechanism
T01: Challenging rock engineering projectsLianjin TAO, Haixiang ZHANG, Zhibo JIA, Ming SHI, Zhigang WANG, Cheng SHIKey Laboratory of Urban Security and Disaster Engineering of China Ministry of Education, Beijing University of Technology, People's Republic of ChinaStudy on anti-dislocation measures for railway tunnels crossing active faults in complex and dangerous mountainous areasThe geological environment of the Tibetan plateau region is complex, with extensive development of active faults. Tunnels built in this area would be greatly affected by active faults. To study the anti-fault measures for the tunnel, active faults were counted along the railway. We then analyze measures to reduce dislocations and review existing fundamental conclusions on fault prevention. Preliminary results on the staggered classification of active faults have been obtained through a literature analysis. Anti-fracture measures that might be applied to the railway were identified. It includes the use of segmental composite lining structure (such as steel-mixed composite structure), improving the stiffness of flexible articulated joints (such as corrugated steel), increasing the width of articulated joints, fault fracture zone core expansion design and other measures. The results can be used as a basis for a quantitative study of anti-fracture measures. | Mountain railway tunnel, active faults, anti-dislocation measures
T01: Challenging rock engineering projectsHanlim KIM (1), Gyeongjo MIN (1), Gyeonggyu KIM (1), Youngjun KIM (1), Jusuk YANG (2), Kyungjae YUN (2), Sangho CHO (1)1: Jeonbuk National University, Korea, Jeonju, South Korea; 2: Agency for Defense Development, Daejeon, South KoreaA method for investigating dynamic direct shear behavior of artificial jointed rocks using CNS direct shear box and Long Bar Drop Impact (LBDI) SystemUnderstanding the shear behavior of a discontinuity in rock masses is vital for the proper design and construction of underground structures, considering their structural stability and cost efficiency. A static-based shear behavior is generally considered for designing these structures; however, rocks often undergo dynamic loading, such as seismic, blast, and percussive loading. Various studies have reported that rocks exhibit significantly different mechanical behaviors under dynamic loading, and frictional behavior may also exhibit different behaviors. In this study, a direct shear box and Long Bar Drop Impact (LBDI) apparatus were utilized to examine the dynamic joint shear behavior of artificially jointed rocks. Various dynamic loadings and initial normal stresses under constant normal stiffness (CNS) were considered in the experiment. The experimental results revealed that the dynamic joint shear strength depended on the initial normal stress and joint roughness. | Long bar drop impact (LBDI) apparatus, Direct shear box, Constant Normal Stiffness (CNS) condition, Dynamic joint shear behavior, Artificial jointed specimen
T01: Challenging rock engineering projectsAlfio DI GIOVANNI, Carmine TODARO, Simone SALTARIN, Marilena CARDUPolitecnico di Torino, Turin, ItalyThe phenomenon of tools' wear in a marble quarry: laboratory tests to evaluate the performance of conditioning as a wear preventerExploitation with a chain saw cutting machine has been the ordinary industrial practice in marble excavation for over thirty years, due to its ability to adapt to difficult environments and to guarantee a high level of safety during the cutting phase. Nevertheless, the presence of impurities in the calcite matrix, e.g. quartz, leads to the problem of rapid and unusual wear on cutting tools. In this study, two laboratory tests were selected and carried out to estimate the rock's wear potential: the CERCHAR Abrasivity test and the Soil Abrasion Test Apparatus (SATA). The results highlight a high degree of abrasivity in dry conditions, which was satisfactorily reduced by using water and additives. This mixture, typically used in tunnelling applications, is intended to decrease the wear from rock excavation and a significant reduction of this phenomenon has been noticed. | dimension stone exploitation, tool wear, Soil Abrasion Test Apparatus, CERCHAR Abrasivity test, wear reduction
T01: Challenging rock engineering projectsAndreas GORICKI (1), Vipin PARIHAR (2)1: 3G Gruppe Geotechnik Graz ZT GmbH, Austria; 2: Afcons Infrastructure Limited, IndiaPandoh Highway Tunnels in Indian Himalaya - a rock mechanical challenge in design and constructionThe National Highway NH-21 in the Indian State of Himachal Pradesh is developed into a 4-lane divided dual carriageway. The road section between Chandigarh and Manali with a length of approximately 21 km is located in topographically very difficult terrain where the Beas River formed a deep and narrow canyon with high and steep rock slopes. The paper describes the challenges in the design and the construction of the EPC Contract for six tunnels with a total single bore length of approximately 20 km. This includes geological design, NATM excavation design and detailed structural design for the rock tunnels in different tectonic formations. The variable rock mass conditions in combination with the short lateral distance to the very steep canyon slopes resulted in demanding rock mass behaviour and various difficulties to be solved during excavations. | NATM, tunnel, design, construction
T01: Challenging rock engineering projectsJose Allan MAIA (1), Teofilo COSTA (1), Anderson FONINI (2), Felipe GOBBI (2), Ricardo MENEZES (2), Gonçalo SONAGLIO (2), Fabiano MADRID (2)1: Vale S.A., Brazil; 2: FGS Geotecnia, BrazilDesign Review of the Remediation Project of a Highly Weathered Open Pit Wall from a Closed Iron Ore Mine in BrazilIn the late 90s, the excavation of an open pit mine was initiated in the Iron Quadrangle, a rich iron ore region situated in southeast Brazil. During years of excavation and mining duties, but especially after reaching its maximum depth, many instabilities occurred in the north wall, which presents about 500 m height and overall slope inclination that fluctuates between 30° to 35°. In the 2010s, a Real Aperture Radar and a series of prisms distributed across this wall indicated a total displacement of about 65 cm in 120 days during severe rainstorms. More recently, in the 2020s, InSAR data have shown that the displacements are still occurring after many slope failures, especially during the rainy season. As a result, the extensive erosion process accelerated the wall unloading generating a net of several unstable surfaces (comprising millions of cubic meters) controlled by the regional structural setting. Thus, during the design review of the remediation project, according to the reduced data available, several analyses were conducted to confirm the geotechnical parameters obtained from field and lab tests and assess the failure depth from back analyses. Finally, the design review service shows that the remediation proposed by the basic design could no longer address effective treatments for the decommissioning design of the north wall, but the remediation actions are still valid. | Decommissioning, Surface mining, Design review, Complex geology, Tropical environment, Weak rocks
T01: Challenging rock engineering projectsRaphael Perpetuo SOARES, Joao Pedro AMARAL, Gerson Rincon RIBEIROAngloGold Ashanti, BrazilGeotechnical Stope IndexThe Geotechnical Stope Index aims to highlight the ore's dilution potential. The profile uses calculations to consider historical observations and geotechnical data analysis to identify potential geotechnical hazards about overbreaks in sublevel stoping. After each step, a column called "Estimated Dilution" is added to compare previous estimations with actual results, using a reconciliation method to calibrate the system's predictability feature. The Stope Index input limits have been calibrated based on stope performance data to provide realistic dilution estimations. This suggests that the system is being used in a mining or excavation context to estimate the amount of material that is lost or mixed in with the extracted ore during the mining process. By comparing the estimated dilution with the actual dilution, the system can improve its accuracy over time and provide more reliable estimates. This system is the geotechnical risk inserted in the mining plan before the mining production sequencing. | Stope Index, dilution, mine planning, geotechnical classification
T01: Challenging rock engineering projectsThomas PILGERSTORFER (1), Katharina HOFER (2), Yvonne MONSBERGER (3), Jürgen VORINGER (4)1: Geoconsult ZT GmbH, Puch/Hallein, Austria; 2: ASFiNAG Bau Management GmbH, Ansfelden, Austria; 3: ASFiNAG Bau Management GmbH, Großwilfersdorf, Austria; 4: Swietelsky Tunnelbau GmbH & CO KG, Salzburg, AustriaBurgenland’s first tunnel takes its tribute – geotechnical retrospective of a tunnel collapseThe tunnel Rudersdorf, which is part of the S7 Fürstenfelder motorway is a two-lane twin tube road tunnel with seven cross passages, and has a length of approx. 1.785 m. The overburden of Burgenland’s first tunnel ranges between 2 and 72 m. Especially the excavation works in the northern tube were accompanied by several geotechnical challenges, which required an adaption of the excavation concept and the support measures. In the subsequently excavated southern tube, situated in similar geological and geotechnical conditions, a collapse of the tunnel occurred after about 100 m of tunnel advance with a material ingress of approx. 1.600 m³. The paper discusses the rock mechanical processes which led to the collapse on the basis of the evaluation of monitoring data, the observed system behavior before the collapse, the observations during the re-excavation works of the collapsed tunnel section, and the encountered geological and geotechnical conditions. | NATM, shallow tunnel, system behaviour, geotechnical monitoring, tunnel collapse