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This paper summarizes the results of probe drilling carried out ahead of TBMs in two difficult tunneling projects in Turkey. The tunnels have completely different geological characteristics which necessitated two different methods of data analysis. Melen Water Tunnel was excavated under Istanbul Bosphorus within sedimentary rocks which are cut freq...
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In underground mining operations, excavation of underground openings are generaly performed for many different purposes such as waste storage, subway, highway, railway, irrigation, hydroelectric, sewerage and wastewater tunnels. In Turkey, these openings can be formed by various mechanical excavation equipments such as drilling-blasting method whic...
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... It should be noted that the potential damage caused by groundwater inflows mainly depends on geological, hydrogeological and tunnelling conditions of rocks surrounding the tunnels. For instance, geological features such as fractures and faults are among the factors related to unexpected groundwater inflows into tunnels (Bilgin & Ates 2016). The time taken for these inflows to change from temporary to persistent inflows depends not only on the aforementioned conditions, but also on the extent of the damage generated. ...
Predicting groundwater inflow into tunnels is essential to ensure the safe accessibility and stability of underground excavations and to attenuate any associated risks. Such predictions have attracted much attention due to their tremendous importance and the challenge of determining them accurately. Over recent decades, based on diverse methods, researchers have developed many relevant analytical solutions. Considering these research efforts, this article identifies and describes the most critical key factors that strongly influence the accuracy of groundwater inflow predictions in rock tunnels. In addition, it presents a synthesis of the latest advances in analytical solutions developed for this purpose. These key factors are mainly time dependency of groundwater inflows, water-bearing structures, aquifer thickness,
hydraulic head and groundwater drawdown, rock permeability and hydraulic conductivity, fracture aperture, and rainfall data. For
instance, groundwater inflows into tunnels comprise two stages. However, the transition between the stages is not always rapid and, for tunnels located in faulted karst terrains and water-rich areas, groundwater inflows can exceed 1,000 L/min/m. Under high stress, rock permeability can increase up to three times near the inevitable excavation-damaged zones, and groundwater inflows into tunnels can be significantly affected. Despite the enormous amount of research already conducted, improvements in the accuracy of predicting groundwater inflows into rock tunnels are still needed and strongly suggested.
... 12 Several studies have been conducted to investigate the geological conditions ahead of the tunnel face by pressure monitoring using a hydraulic drilling machine. [13][14][15][16][17][18][19][20][21] Furthermore, many researchers have carried out studies using artificial intelligence technologies, such as machine learning, to analyze the relationships among drilling datasets, and predict geological conditions, [22][23][24] concluding that MWD techniques are an objective and reliable method for assessing geological conditions ahead of the tunnel excavation face. ...
Pre-investigation of geological conditions beyond the excavation face is crucial for assessment of safety and design in underground construction. This study developed a boring data monitoring system equipped for a multi-setting smart-investigation of the ground and pre-large hole boring (MSP) machine that typically drills a horizontal distance of 50 m to reduce blast-induced vibration. The monitoring system was applied to the tunnel construction site, which drills 40 m with the MSP method to investigate the geological conditions ahead of the excavation face. In addition, the analysis results of the boring data were compared with the observed images taken inside the holes, using a borehole alignment tracking and ground exploration system. The analysis of the boring data indicated rapid changes in pressure and boring speed with changes in geological conditions. Furthermore, the ground conditions ahead of the excavation face can be classified into three stages based on the boring pressure and speed variations. Therefore, these boring data can be the basis for predicting the geological conditions beyond the excavation face without additional effort and processes, and can help in ensuring the safety and efficiency of tunnel construction projects.
... Bilgin (2016) emphasized these difficulties as follows: "The geology of Türkiye is very complex and major Northern and Eastern Faults including minor faults associated with these faults create tremendous problems." Therefore, in recent years, many railway and highway tunnels in Turkey have been constructed under difficult geological conditions (Dalgic, 2002 andDalgic 2003;Aydin et al., 2004;, 2012and Aksoy et al. 2014Bilgin and Algan, 2012;Ozcelik, 2016;Bilgin and Ates, 2016;Kaya and Bulut, 2019;Komu et al., 2020;Aygar and Gokceoglu, 2020, 2021a, b, and Aygar and Gokceoglu 2021cApaydin, 2021;Satici and Topal, 2021;Bilgin and Acun, 2021). ...
The Dogancay T1 tunnel, projected within the scope of the Ankara-Istanbul high-speed train project, is being excavated entirely through clay and cohesionless units and is located in the North Anatolian Fault Zone (NAFZ). To determine the support system in the tunnel, innovative approaches require investigation through analytical and numerical methods to evaluate their suitability. The present study investigates rigid support systems, including the intermediate lining and pre-support excavation techniques in the new Austrian tunneling method (NATM), with 3D numerical analyses. The tunnel is in a seismically active zone, and the study also addresses the seismic sustainability of the proposed support system. The results of analyses showed that the proposed excavation and support system can be successfully implemented in the Dogancay T1 tunnel. The case study provides guidelines for investigating tunnel excavation and support systems in poor ground conditions in tectonically active zones.
... Advanced horizontal drilling has been extensively used as the intuitive technique for geological exploration (Fransson and Gustafson, 2000). According to the drilling rate, driving pressure, core samples, torque and effluent, geological features ahead of the tunnel face can be directly identified (Kahraman et al., 2003;Bilgin and Ates, 2016). Advanced horizontal drilling can also be used for a supplement to geophysical ahead prospecting (Loew et al., 2015;Linde-Arias et al., 2019). ...
Water and mud inrush is one of the most important geohazards in underground engineering. The paper presents a state-of-the-art review of the current understanding of this type of geohazard. Emphasis is placed on recorded the geneses and evolution processes of water and mud inrush, as well as relevant prevention methods. In particular, the geneses of this inrush hazard are initially discussed, by providing hazard cases during the past several decades. This is followed by a review of the various forming processes and corresponding research methods (including theoretical, numerical, experimental methods) for water and mud inrush, which can be used to pave the ways for hazard prevention and future research. Subsequently, the paper provides a summary of relevant hazard prevention methods employed by academics and practitioners, followed by a short discussion on the achievements and limitations of each method. Throughout the presentation, the current overall gaps in understanding water and mud inrush hazards are identified in an attempt to stimulate further research in these promising directions by the research community.
... The author in [7] said that the torque thrust during drilling was directly affected by the feed thrust, and there was a definite relation between feed thrust and torque. Similarly, other studies [8,9,10,11,12,13] reported successful results in predicting the in-situ properties of rocks with the help of uniaxial compressive strength, point load strength, RQD (Rock Quality Designation), etc. The penetration rate obtained from horizontal probe drills must be analyzed with a correct approach and must be freed from errors from the machine and operator to fully reflect the relevant characteristics. ...
Research methods are needed during excavations with TBM (Tunnel Boring Machine) to ensure safe excavation conditions because it is not possible to see and continuously monitor the excavation face completely. One of the most dangerous conditions expected in the tunnels that will be opened underwater is sudden and high water ingress. To detect possible water ingress, one of the most reliable methods that can be used is to perform horizontal probe drills. With water flow, the dimension of the danger increases more if weak ground conditions and fault and/or crush zones are monitored intensively. Such conditions may cause serious damage to TBM, and sudden washing can cause collapse and deviations in the vertical and horizontal axes. In this sense, considering the negativities of the geological and hydrogeological conditions of the Bosphorus Tunnel passing beneath the Bosphorus Strait, it was set as a contract condition that TBM excavation would be performed according to the results of the horizontal probe drills. During the excavation along the tunnel route, horizontal probe drills were performed at an average of 36 m. The Instantaneous Advance Speed (IAS) with 1-cm intervals, Thrust Pressure (TP), Torque (TQ), and washing water thrusts of the horizontal probe drills were recorded in this respect.-In this article, the Instantaneous Advance Speed (IAS) values recorded during drilling were normalized with torque and thrust values, respectively. In this way, the changes in advance speeds were determined, and it was determined whether these changes were caused by increased thrusts, and/or torque or lithological changes. The relations between normalized Instantaneous Advance Speed (IAS) values and the RQD values at the tunnel excavation level of 14 vertical drillings built on the tunnel route were revealed. These relationships showed that the speed of Instantaneous Advance Speeds decreased as RQD values increased. This study must be proceeded by analyzing statistical data with a database containing more vertical drilling data to develop the TBM performance prediction model in such a way that the relations between formation characteristics and horizontal probe drill performance are revealed based on horizontal probe drill data.
... • Instability of the excavation face/roof • Excessive overbreak of the tunnel contour • Cutterhead jamming/damage • Large water inflow Bilgin and Ates (2016) Bayati and Hamidi (2017) Clay soil Either full face or mixed face • Cutterhead clogging • Adhesion problems Thewes (2004), Thewes and Hollmann (2015) Squeezing ground Time dependent large deformation which occurs around the tunnel associated with creep caused by exceeding a limiting shear stress ...
... • Shield blockage/jamming problems Barla (2001), Bilgin and Algan (2012), Bilgin et al., (2016) Swelling ground Advances into the tunnel chiefly on account of expansion. The capacity to swell seems to be limited to those rocks that contain minerals with a high swelling capacity ...
... • Cutter jamming • Affects the production cycle due to sticky property of muck Bilgin et al., (2016) High in-situ stress In areas of high in situ stress, rock bursts, spalling and collapse are common. (Hunt and Del Nero, 2011, Zhao and Gong, 2015, Shirlaw, 2015 (Bieniawski, 1976, Barton et al., 1974, Hoek and Brown, 1998, 토사와는 달리 TBM의 굴진성능과 암반을 특성화하 는 인자들 간의 상관관계를 바탕으로 TBM 성능예측 기법들이 지속적으로 연구되고 있다 (Gong and Zhao, 2007, Hamidi et al., 2010, Hassanpour et al., 2009, 2010, Delisio et al., 2013, Delisio and Zhao, 2014, Yagiz, 2006, 2008 (Boone et al., 1998, Poot et al., 2000, Hunt, 2002 Fig. 9. Interaction between disc cutter and ground in different levels of granular ground compaction (Barzegari et al., 2014) Goss (2002) (Fig. 14). ...
... Probe holes, on the other hand, are cheap, fast and easy to perform [3]. The problem is that interpretation of data is very subjective, generally leaving the responsibility in the hands of the operator. ...
The aim of this chapter is to introduce one of the most comprehensive and successful umbrella arch (UA) operations used ahead of a TBM in the Kargi tunnel in blocky ground and complex geology in Turkey. The increase of TBM torque and the change in penetration rate of the probe drill were used as criteria for the application of UA. The umbrella arch is a very useful technique to prevent the jamming of the TBM cutterhead in blocky ground, as proved on the Kargi project, but it is important to note that some basic criteria should be established for using this technique. A map showing the contours of changing probe drilling rates and change of torque values were used as the two basic criteria in the Kargi project. The increase of TBM torque up to a certain limit can be used as a critical torque value for using UA. This was established as 42,000 kNm in the Kargi project. The umbrella arch was applied nine times in the Kargi project. As the crew gained experience, time for drilling and injection was reduced from five days to two. However, it should be said that the UA is a good alternative to excavating bypass tunnels for releasing a blocked cutterhead.
This chapter summarizes the results of probe drilling carried out ahead of TBMs in Melen and Kargi projects in a very complex geology. In summary it may be concluded that normalized penetration rate of a probe drill is a good indicator for detecting weak zones ahead of a tunnel. Probe drilling rate changed with changing geological formations and showed sharp increases and decreases in transition zones. Probe drilling rate is also very much affected in fault zones. In some cases, probe drilling rate increased within fault zones due to swelling and squeezing characteristics of the gauge materials. The method of analysis of probe drilling rate data in the Melen project permitted the defining of a critical normalized probe drilling value. Values higher than the predetermined critical value point out critical geological zones susceptible to pressurized water ingress. TBM thrust and torque values increased with decreasing probe drill penetration rates in competent hard rock formations in the Kargi energy tunnel. However, this study introduced a new concept of TBM thrust/probe drilling penetration rate and TBM torque/probe drilling penetration rate ratios explaining the variation of penetration rates in a statistically more reliable manner. This concept showed that by observing closely the variation of TBM thrust and torque values it is possible to predict the transient and fault zones, dictating the carrying out of umbrella arching, which will strengthen the weak zone in front of the tunnel.
