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At the request of the authors, the article titled “The Mechanical Performance of Shear Key of Immersed Tube Tunnel with Differential Foundation Settlement” [1] has been retracted. The authors found that there was an error in the method used for the data processing as temperature change was not considered, and the results were inconsistent with those in the thesis of Shengli [2], who was acknowledged in the article. Thus, the accuracy of the reported data and the conclusions of this article are not reliable.

For long deep tunnels as currently under construction through the Alps, mechanized excavation using tunnel boring machines (TBMs) contributes significantly to savings in construction time and costs. Questions are, however, posed due to the severe ground conditions which are in cases anticipated or encountered along the main tunnel alignment. A major geological hazard is the squeezing of weak rocks, but also brittle failure can represent a significant problem. For the design of mechanized tunnelling in such conditions, the complex interaction between the rock mass, the tunnel machine, its system components, and the tunnel support need to be analysed in detail and this can be carried out by three-dimensional (3D) models including all these components. However, the state-of-the-art shows that very few fully 3D models for mechanical deep tunnel excavation in rock have been developed so far. A completely three-dimensional simulator of mechanised tunnel excavation is presented in this paper. The TBM of reference is a technologically advanced double shield TBM designed to cope with both conditions. Design analyses with reference to spalling hazard along the Brenner and squeezing along the Lyon–Turin Base Tunnel are discussed.

Recent experience has shown that test results of standard wind tunnel models under off-design conditions could be a useful aid in preparations of some nonstandard wind tunnel tests. However, reference data for such conditions do not exist, or they are scarce. Therefore, off-design transonic wind tunnel tests of the HB-2 standard models were executed in the VTI T-38 wind tunnel as a supplement to the supersonic tests of the same models under design-intent conditions, for which reference results were available. New tests were conducted so that test envelopes partially overlapped with those from available supersonic reference data. Good agreements of results with references were confirmed in the overlapped ranges, so it was assumed that, by implication, the obtained results were also valid in the transonic range of conditions, with an observation that the effects of sting diameter were much more pronounced in the transonic range than in the supersonic one. HB-2 models were tested in two sizes, using two different wind tunnel balances for each model, so that the results can be used with more confidence.

Carpal tunnel syndrome is the most common peripheral nerve entrapment syndrome worldwide. The clinical symptoms and physical examination findings in patients with this syndrome are recognised widely and various treatments exist, including non-surgical and surgical options. Despite these advantages, there is a paucity of evidence about the best approaches for assessment of carpal tunnel syndrome and to guide treatment decisions. More objective methods for assessment, including electrodiagnostic testing and nerve imaging, provide additional information about the extent of axonal involvement and structural change, but their exact benefit to patients is unknown. Although the best means of integrating clinical, functional, and anatomical information for selecting treatment choices has not yet been identified, patients can be diagnosed quickly and respond well to treatment. The high prevalence of carpal tunnel syndrome, its effects on quality of life, and the cost that disease burden generates to health systems make it important to identify the research priorities that will be resolved in clinical trials.

Cross diaphragm (CRD) method divides the tunnel into multiple pilot tunnels to reduce the span of a single excavation, which is beneficial to reduce the disturbance of excavation construction to surrounding rocks. In this method, the excavation sequence of pilot tunnels is a key factor affecting the excavation disturbance. In this study, two schemes of excavation sequence of pilot tunnels were simulated by numerical method, based on a newly built shallow buried rectangular tunnel using CRD method. By comparing and analyzing the vertical displacements of tunnel surrounding rocks, ground surface settlements, crown settlements and bending moment of the primary support structure, the surrounding rock deformation characteristics and trends of the tunnel were revealed, which determined the more reasonable excavation sequence scheme for the construction of the rectangular tunnel. By comparing with the field monitoring data, the numerical simulation results were verified to a certain extent. In addition, the comparison of calculation results obtained from the Mohr–Coulomb (MC) and the hardening soil small (HSS) constitutive models were discussed. The investigation results show that: (1) the displacement of surrounding rock and bending moment of the primary support structure are closely related to the excavation sequence of the pilot tunnels; (2) the deformation trends revealed by the numerical results are similar to those from the field data; (3) according to the field construction process, the asymmetric excavation sequence of \"left upper pilot tunnel—left lower pilot tunnel—right-upper pilot tunnel—right lower pilot tunnel\" is safe and reliable for the rectangular tunnel construction.HighlightsTwo different excavation sequences of a rectangular tunnel with CRD method were systematically compared and analyzed, and the recommended excavation sequence was proposed.The displacement of surrounding rock and bending moment of primary support structure were closely related to the excavation sequences of pilot tunnels.The details of the excavation and construction process of a rectangular tunnel using CRD method were shown by pictures.Compared with the HSS model, the Mohr Coulomb (MC) model may lead to larger deformation in significant unloading / reloading problems.

In order to study the influence of shield tunneling on existing high-speed railway lines. Combined with centrifuge test and three-dimensional numerical simulation, the dynamic response of shield tunnel undercrossing existing high-speed railway tunnel was studied, and the influence of settlement joint and steel pipe pile reinforcement on existing tunnel was analyzed. The results show that: (1) the construction joints of existing tunnels significantly reduce the shielding effect of existing high-speed railway tunnels on the ground; (2) The settlement value of the existing tunnel caused by double-line shield tunnel construction needs to be controlled by steel pipe pile reinforcement to meet the requirements of the specification; (3) The double-line shield tunnel construction has little effect on the internal force of the existing high-speed railway tunnel, and the reinforcement of the high-speed railway tunnel lining meets the stress requirements.

Throughout construction process of a tunnel in an active tectonic region, it may be impossible to avoid active faults. Active faults create two adverse effects on the tunnels which are sudden fault displacement and weak ground conditions in fault zone. If a tunnel crossed by an active fault, the tunnel might be damaged by sudden movement of the fault. However, the main goal is to localize this damage without complete loss of tunnel. In this study, a special design developed for a wide span tunnel cut by an active fault is presented and the performance of the design is verified by numerical analyses. T9 tunnel was constructed within the scope of Ankara–Sivas High-Speed Train Project, Turkey, and the special design at the intersection of T9 tunnel with the Akdagmadeni active fault is the main subject of this study. T9 tunnel predominantly passes through agglomerate, basalt, marble and gneiss units and the tunnel route crosses the Akdagmadeni fault at around Km: 327 + 915. At this location, major deformations occurred in the tunnel and the tunnel excavation had to stop for a certain period. After the re-design phase, a special tunnel support system for this location were developed and proposed design was analyzed with numerical analyses. In addition, the possible displacement of the Akdagmadeni fault was estimated and the inner lining was re-designed considering the seismic parameters (i.e. peak ground acceleration and maximum displacement during a large earthquake). Consequently, in the present study, the effects of active fault crossing on the tunnel were explained and a special inner lining design was proposed to localize the possible damages, which are originated from the sudden displacement of the active fault.

Earthquakes such as Kobe, Chi-Chi, Wenchuan, and many more damaged the rock tunnels to various extents. To understand the vulnerability of rock tunnels caused by earthquakes, the damage degree and damage classification are major components. The damage degree and descriptions in the post-seismic damage classifications of rock tunnels are modified by researchers for every seismic event based on the amount of damage. This implies that existing post-seismic damage classifications are not uniform or consistent. The existing classifications are based on data from one or a maximum of three seismic events and also are site-specific, and lack a generalized view of the problem. To overcome such limitations, this study proposes a new post-seismic damage classification of rock tunnels. This classification is obtained from the largest global seismic damage database which contains information on 285 rock tunnels damaged by 26 earthquakes. This study introduces seven tunnel damage classes for different damage degrees namely None, Very Slight, Slight, Moderate, Severe, Extremely Severe, and Collapse with their detailed damage descriptions. Further, the influence of seismic, geological, and structural parameters are summarized from the database. The efficacy of this classification and conclusions from the influence parameters are validated by applying it to the five-rock tunnels damaged by Luding (2022), and Menyuan (2022) earthquakes in China and Kahramanmaraş earthquake sequences (2023) in Türkiye. The proposed classification shows a good agreement with the damage degree and its description for these five rock tunnels. Thus, the proposed damage classification and outcomes of influence parameters using such a large database can be utilized to understand the damage levels caused in the tunnel after an earthquake and for performing post-seismic damage assessment of rock tunnels.

Tunnel excavation in squeezing ground exhibits large time-dependent and often anisotropic deformation. Within the context of the Fréjus road tunnel and its safety gallery excavated under the Alps between France and Italy, an interesting configuration of two parallel tunnels under squeezing ground conditions is observed. The special feature of this case study lies in the fact that both tunnels have been excavated in similar geotechnical conditions but with different excavation techniques. The road tunnel was excavated with conventional drill and blast methods in the 70s, whereas the safety gallery was excavated between 2009 and 2016 with a single-shield tunnel boring machine (TBM). This paper presents monitoring data processing and numerical simulations of both tunnels with the aim of studying the influence of the excavation method on the time-dependent tunnel response. A calibration of a visco-elasto-plastic anisotropic constitutive model based on the back-analysis of convergence measurements retrieved during the excavation of the Fréjus road tunnel is carried out. The identified ground behavior can be extrapolated to the parallel zones of the safety gallery. In particular, we are interested in the prediction of the stress state in the segmental lining of the gallery during its excavation and the comparison with in situ measurements. It is shown that the time-dependent behavior of the ground is affected by the excavation technique. Finally, an attempt to predict the long-term response of both tunnels is proposed.