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Excavation‐induced rock failure and deformation near an underground opening boundary is closely associated with the intermediate principal stress, strain softening and rock mass dilation. By combining theoretical analysis and numerical simulation to explore the mechanical evolution of the roadway surrounding rock during excavation. The elastic–plastic criterion solutions for surrounding rock stress, displacement, and the plastic zone of a circular roadway were deduced by including the intermediate principal stress, strain softening and rock mass dilation, based on the Drucker–Prager criterion and the nonassociated flow rule. Furthermore, ABAQUS finite element software was utilized for numerical simulations to scrutinize the influence of mechanical parameters on stress redistribution, surface displacement, and plastic range. The results of the numerical simulations verify the reliability of the theoretical analysis and affirm the high consistency of the results with the theoretical solution. The research findings indicate that the strength of surrounding rock is significantly influenced by the intermediate principal stress, and the deformation and failure of rock mass are primarily impacted by rock mass dilation, while strain softening mainly affects the thickness of the fractured zone. Moreover, the study reveals that enhancing the residual strength of the surrounding rock can improve its resistance to deformation and failure. Furthermore, the excavation of the roadway is observed to increase the original rock stress in the surrounding rock, but increasing the ground support strength effectively controls the deformation and failure of surrounding rock. Ultimately, the research outcomes offer valuable references for engineering calculations and ground support design of surrounding rock in deep roadways. [ABSTRACT FROM AUTHOR]

To improve the extraction of coal resources, gob‐side entry driving is gradually being promoted and applied. However, as the thickness of the coal seam increases, the deformation control of the roadway becomes more difficult. Aiming at this problem, a combination of theoretical calculation, numerical simulation, and field test was used to analyze the aspects of the stress environment, surrounding rock properties, and support forms. The phenomenon and mechanization of intensified deformation and failure of roadway with increasing coal seam thickness were revealed. The specific results include: (1) The ratio of principal stress at the excavation position controls the maximum failure depth of roadway, and the direction of principal stress determines the location of the maximum failure depth; (2) As the thickness of the coal seam increases, the properties of the surrounding rock at the excavation position decrease, the principal stress ratio increases, and the deflection angle of the principal stress increases, which lead to an intensification of the deformation and failure of the roadway. Based on the deformation and failure characteristics of the roadway and the shortcomings of the original support form, a control strategy and support scheme based on a new support structure called "Anchor Cable with C‐shaped Tube" is proposed, which has achieved better deformation control effect in on‐site application. [ABSTRACT FROM AUTHOR]

Non‐uniformly distributed in‐situ stress around the tunnel is a significant factor inducing various geohazards during tunnel excavation in the rock mass, and the anisotropy of the rock mass would further differentiate the in‐situ stress state around the tunnel. To ensure the safety of tunnel construction and operation, it is necessary to deeply analyze the stress distribution law and mechanical mechanism of the orthogonally anisotropic elastic media the around tunnel. This paper presents a complex variable function method for the elliptical tunnel in an orthogonally anisotropic elastic full‐space under non‐uniform in‐situ stress. To obtain the analytical solution, the affine transform and conformal mapping are applied to consider the orthogonal anisotropy of material and the ellipticity of the tunnel. A numerical series fitting method is introduced to describe the non‐uniformly distributed load, and then the stress solution around tunnel is further obtained. The comparisons with the existing literature, numerical solutions and model tests are provided to verify the correctness of the proposed method. Finally, the convergence study and the numerical analysis on the stress distribution are given graphically. [ABSTRACT FROM AUTHOR]

Strainburst often occurs in the loading process of tangential stress concentration from surrounding rocks after excavation and unloading of deep rock mass. The concentrated tangential stress is relatively larger on the tunnel walls, which decreases towards the interior of surrounding rocks with a certain gradient. To explore the fracture evolution characteristics of surrounding rocks under different tangential gradient stresses and understand various phenomena in the strainburst process, a large‐scale true‐triaxial gradient and hydraulic‐pneumatic composite loading rockburst test device was adopted to carry out the strainburst tests under four different gradient stresses. Based on the macroscopic failure phenomena, distribution of rockburst debris, macro‐micro morphology of failure cross section, and monitored data of acoustic emission (AE), the fracture evolution of rockburst specimens was analyzed under different stress gradient loadings. The results indicate that the stress gradient has an obvious influence on the fracture characteristics, resulting in different rockburst phenomena. With the increase of stress gradient, the failure stress of rockburst decreases, while the dynamic failure characteristics of rockburst trends to be significant. The increase of stress gradient contributes to higher fragmentation degree of debris, more uniform distribution and better continuity. The total number of cracks in the model decreases with the rise of the stress gradient, and the proportion of shear failure increases, which is the main reason for the enhancement of the rockburst intensity. [ABSTRACT FROM AUTHOR]

This paper presents an ordinary state‐based peridynamic model to simulate failure in porous rocks and its application in the rock excavation processes. Rock indentation is a fundamental process for mechanical rock fracturing, which is frequently encountered in rock excavation. To model crushing occurring under high triaxial loads observed in the rock indentation experiments, peridynamic model has been extended to consider the pore‐collapse phenomenon. Rock heterogeneity is considered in the simulations by sampling the strength parameters from a probability distribution function. The model is qualitatively validated using the acoustic emission data from the indentation experiments. The developed model is able to form a crushed zone, which serves as the point of initiation for tensile cracks, which split the specimen. Quantitative validation relies on the comparison of the force‐penetration data as well as the indentation pressure‐penetration data obtained from the simulations and experiments performed on Bentheim Sandstone specimens. [ABSTRACT FROM AUTHOR]

One of the main hazards during tunnel boring machine (TBM) excavation in hard rock is related to the occurrence of unforeseen adverse conditions, leading to unfavourable rock mass behaviour during tunnel boring. In this respect, the continuous analyses of TBM excavation parameters may represent an interesting tool for a continuous monitoring of geotechnical conditions at the tunnel face and for early detection of changing ground conditions in the rock mass. This work provides a back‐analysis of TBM data recorded during the excavation of the Frejus Safety Tunnel, bored across the French‐Italian border in the Western Alps. It is a 13 km‐long tunnel excavated by a 9.4 m diameter, single‐shield TBM through strongly anisotropic calcareous schist, with cover up to 1800 m. Main problems faced during TBM excavation were related to the local occurrence of buckling‐related convergence and consequent asymmetrical loading on the precast segment rings. Correlating TBM performance parameters to the encountered geological and geomechanical conditions provides the possibility to identify which parameters are most affected by geomechanical properties of the rock mass at the tunnel face and by rock mass behaviour. Conversely, the analysis indicates which parameters can be adopted as monitoring tool of ground conditions during TBM advance. In addition, this work highlights how buckling phenomena can be distinguished, in terms of TBM operation and performance, from other adverse conditions as, e.g., blocky ground or squeezing. [ABSTRACT FROM AUTHOR]

Boulder‐sized clasts are common on the surface of Mars, and many are sufficiently large to be resolved by the high resolution imaging science experiment (HiRISE) camera aboard the Mars reconnaissance orbiter. The size, number, and location of boulders on the surface and their spatial distribution can reveal the processes that have operated on the surface, including boulder erosion, burial, impact excavation, and other mechanisms of boulder transport and generation. However, quantitative analysis of statistically significant boulder populations, which could inform these processes, entails prohibitively laborious manual segmentation, granulometry, and morphometry measurements over large areas. Here, we develop, describe, and validate an automated tool to locate and measure boulders on the Martian surface: the Martian Boulder Automatic Recognition System (MBARS). Our open‐source Python‐based toolkit automatically measures boulder diameter and height in HiRISE images enabling rapid and accurate assessments of boulder populations. We compare our algorithm with existing boulder‐counting methods, manual analyses, and objects of known size to verify accuracy and precision. Additionally, we test how MBARS quantitatively characterizes boulders around an impact crater in the Martian northern lowlands. We compare this to previous work on rock excavation during impact cratering using manually counted boulders around lunar craters. Plain Language Summary: Large boulders (>1 m diameter) are widely distributed on the Martian surface. They are easily observed from orbit, making them visible with high‐resolution imaging. Mapping the location, number, and size of boulders is helpful for understanding which geological processes bring boulders to the surface, move them around, and fragment them into smaller rocks and soil. Here, we describe and validate the Martian Boulder Automatic Recognition System (MBARS), a set of tools that automatically locates and measures boulders in high‐resolution images of the Martian surface. We compare results generated by MBARS with results from other automated boulder‐measuring tools as well as with results from manual boulder measurements to ensure accuracy. We also use MBARS to map boulders around an impact crater on Mars and compare the boulder distribution to a similar‐sized crater on the Moon. Key Points: The Martian Boulder Automatic Recognition System (MBARS) is a new tool to detect and measure boulders on the Martian surfaceMBARS is comparably or more accurate than prior published algorithms that measure bouldersMBARS readily reproduces manually measured results [ABSTRACT FROM AUTHOR]

To analyze the plastic failure process and mechanism of gob floor in the process of close‐distance coal seams mining, a simplified mechanical model of the lateral abutment pressure of the gob was proposed to derive the stress of surrounding rock. The distribution characteristics of gob floor stress deviator were obtained, and the effect of geological parameters (coal depth H and horizontal lateral pressure coefficient λ) were studied. By combining Mohr–Coulomb theory, the influence of surrounding rock cohesion c, internal friction angle φ, different coal seam depths H and different horizontal lateral pressure coefficients λ on the distribution of plastic zone of gob floor was obtained. The results showed that the distribution of the plastic zone under different geological factors is roughly the same as that of the stress deviator. This also proves that the excavation of the rock layer causes the redistribution of stress, which leads to the plastic failure of the surrounding rock. To verify the rationality of the proposed model, industrial experiments and simulation experiments were carried out. The results of on‐site investigation showed that the stability and integrity of surrounding rock in the concentration area of stress deviator is far less than that in the low concentration area. In addition, the acoustic wave test and the displacement field monitoring result of surrounding rock in the simulation experiments of a similar model are basically consistent with the distribution of the stress deviator field. These results agree well with the distribution of stress deviator obtained by theoretical calculation. [ABSTRACT FROM AUTHOR]

It is essential to better understand the large deformation behavior of deep tunnels in weak rock mass to improve the long‐term stability of tunnel surrounding rock mass and design effective supports for squeezing tunnels. This paper introduces two representative large deformation engineering examples to study squeezing behavior. First, new algorithms of contact search, determination of actual contact, and calculation law of contact pairs are proposed for general‐purpose computing on graphics processing units (GPGPUs), by improving the original serial algorithms and developing a compute unified device architecture (CUDA) parallel program, to satisfy the large‐scale rock fracture process simulation. Then, tunnels excavation and rock reinforcement effect including the combination of U‐shaped steel and steel fabric, spray concrete (SMC), and grouting were modeled. The verification, done by comparing the field observation data and the FDEM simulation results of progressive fracture and the tunnel wall convergence displacement, shows that stress remarkable rebalancing after excavation because of high in situ stress, low rock mass strength, and rock mass long‐term strength reduction properties, thus, the rock mass fracture progressively and the rock blocks move continuously, leading to the rock mass volume increase significantly. The result demonstrates one of the root causes of squeezing. To effectively reduce the tunnel wall displacement and maintain tunnel stability, support with higher stiffness or multifactorial combined support methods and grouting with a better bonding effect should be used together. The findings provide insights into the progress of tunnel squeezing and the basis for support design in the squeezing tunnel. [ABSTRACT FROM AUTHOR]

In this study, the peridynamic Drucker‐Prager plastic model with fractional order derivative is proposed to investigate the plastic behavior of surrounding rocks around tunnels, in which the Caputo fractional derivative is employed due to its mathematical simplicity. Instead of utilizing just one parameter for the typical nonassociated flow rule, such as dilation angle, multiple parameters, such as fractional order and interval of fractional derivative, are used to specify the direction of plastic deformation, and the fractional derivative based‐typical flow rule is proposed. As a result, compared with the traditional peridynamic Drucker‐Prager plastic model, the proposed method is a more generalized model including the typical nonassociated flow rule. Besides, based on the PD force density, the strategy of exertion of initial stress is proposed to simulate in‐situ stress in rocks. Taking a block subjected to compression as an example, the impacts of various factors, such as fractional order and interval of fractional derivative, are investigated. A numerical simulation of tunnel excavation in rocks is carried out and the numerical results obtained by the proposed method are verified by comparing with FEM results. [ABSTRACT FROM AUTHOR]

The equivalent quartz content – historic review and its future application in abrasivity prediction The assessment of the abrasion resistance of minerals and their influence is an important aspect in engineering geology and rock mechanics. Questions with regard to rock excavation and the expected wear parameters play a decisive role. Various test methods have been developed over the decades to assess the hardness properties and abrasiveness of minerals and rocks. These include direct tests on rock samples, hardness tests but also parameters derived from mineralogical and petrographic data, such as the equivalent quartz content FEQ. The values used today for determining the FEQu exist since more than 100 years, and are named after August Rosiwal (1860–1923), the pioneer in the field of grinding tests, referred to as Rosiwal factors. The present work deals with this approach, compiles the factors of various authors, and establishes correlations with other hardness parameters. Using laboratory data, the FEQu are calculated and compared amongst the different sources. It is also shown how the FEQu can be directly related to the widely used cerchar test, on the basis of cerchar abrasivity index (CAI) values of selected reference minerals. The FEQu cannot record structural influences, but quartz as a common reference in the cerchar test and FEQu offers the possibility of directly linking the two parameters. [ABSTRACT FROM AUTHOR]

The growth of lunar regolith over time affects surface rock abundance, because larger, less frequent impacts are needed to penetrate thicker regolith developed on older surfaces and excavate rocks. On younger surfaces with thinner regolith, smaller, more frequent impacts are sufficient to excavate rocks. We quantify the correlation between observed rock abundances and age on the lunar surface by comparing Diviner rock abundance data to the surface ages of intercrater parts on the maria. Our observations show the expected negative correlation between age and rock abundance. The commonality of nonzero rock abundance values on ancient surfaces, combined with a simple Monte Carlo model of the rock excavation process, suggest that rocks reexcavated from the regolith volume contribute to the presently observed rock population on the lunar surface. The half‐life of meter‐scale surface rocks most consistent with our observations is 80 ± 20 Myr. Plain Language Summary: The lunar surface is covered by regolith, which includes particles ranging in size from dust to boulders. Past work has suggested that regolith is meters to tens‐of‐meters thick, with average thickness increasing with terrain age. At least in the maria, beneath the regolith is fragmental bedrock. When impacts large enough to penetrate the regolith occur, boulders from this underlying bedrock are excavated onto the surface. Excavating boulders is expected to be more difficult where the regolith is thicker, because thicker regolith limits the ability of craters to eject material from the underlying fragmental bedrock. This implies larger and rarer impacts are needed to excavate rocks on older terrain. We tested this idea by comparing the rock abundance data from the Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter spacecraft with previously obtained crater statistics for part of the maria, excluding the area within and immediately adjacent to D ≥ 1 km craters. We show that older maria have, on average, lower fractional rock abundances, consistent with a thicker regolith on older surfaces influencing rock excavation. Rocks excavated from within the regolith are necessary to be consistent with the continued presence of nonzero rock abundance on old terrains. Key Points: Crater frequency and age of mare units are inversely correlated with rock abundance, consistent with regolith thickening over timeOn old surfaces with thick regolith, the median rock abundance is nonzero, consistent with reexcavation of rocks from within the regolithThe half‐life of meter‐scale surface rocks as derived in the work presented here is 80 ± 20 Myr [ABSTRACT FROM AUTHOR]

On the mix‐shield TBM excavation of the Eppenberg tunnel, unexpected conditions were encountered in both the rock and soil excavations, which resulted in a modified execution of the project. In this case, the openly formulated contract made it possible to take advantage of improvements in the ground and to manage unexpected system behaviour with the right measures in such a way that economical and time‐saving excavation was possible. In all three examples presented in this paper, time is one of the key success factors, because recurring processes result in feedback processes that change the system behaviour more and more rapidly as time goes on. In order to reduce the resulting additional costs and time losses, it is necessary to understand what is happening on site, then evaluate, test and check the possible measures, and finally decide on their implementation in a timely manner. At Eppenberg tunnel, this enabled unexpectedly adverse system behaviour to be overcome in two cases without any major loss of construction time. This was only possible because the responsible persons from all parties involved were able to discuss the situation together and make decisions at short notice. [ABSTRACT FROM AUTHOR]

Large quantities of excavated rocks are generated during tunnel driving. Recycling possibilities and total percentage of recycling are depending on the rock conditions (rock type and rock properties), as well as the applied driving method. If recycling of the excavated rock mass is not possible or reasonable from a technical or economical point of view, the excavated material needs to be deposited in landfills. Thereby, the consumed landfill volume depends on the material volume of non‐recyclable rock and its compactability as a function of the loosening of the rock by excavation and landfill installation. Both, material volume and compactability of the excavated material, are difficult to evaluate in advance. Apart from unpredictable lithological changes and variation of the driving parameters (e.g. depth of advance in conventional driving, contact pressure of tunnel boring machine), external influences – like afflux of water or weather conditions during installation of the material – significantly affect the compactability of the excavated aggregates. In this study, the actual example of phyllitic rock material excavated by conventional drilling and blasting from the main tunnel tubes of the Brenner Base Tunnel has been chosen to take a closer look at the research question concerning the compactability of phyllitic rock material. Since excavation material is increasingly used in construction industry, detailed knowledge on this matter is necessary for a successful application. [ABSTRACT FROM AUTHOR]

The PalaeoEnvironments and ARchaeological Landscapes (PEARL) research project is a joint German–British project with the principal objective of developing a framework of past human occupation and landscape change in south‐eastern Arabia. Fieldwork during 2018 and 2019 involved the systematic survey and excavation of sites in the Rustaq and Ibri regions of Northern Oman, with the aim of establishing the nature and timing of human occupation and landscape change during the Early Holocene period (c. 10,000–7,000 years BP). Further to the findings previously reported, results from recent excavations of the site Hayy al‐Sarh in Rustaq revealed the presence of animal remains, stone and shell beads and stone structures, indicating a large Neolithic settlement with burial areas. In addition, preliminary excavations at a rock shelter site near Ibri have revealed stratified archaeological remains, including a Fasad‐type assemblage. Future fieldwork will further develop archaeological and palaeoenvironmental records to help build a framework for studying cultural and natural developments in Northern Oman. [ABSTRACT FROM AUTHOR]

Summary: The stability of vertical unsupported circular excavations in rock media, obeying generalized Hoek‐Brown yield criterion, has been investigated by using the lower bound finite elements limit analysis. An axisymmetric analysis, composed of a planar domain with a mesh of three‐noded triangular elements, has been carried out. The optimization problem is dealt with by using the semidefinite programming technique avoiding the need of either smoothing the yield surface or making any assumption associated with the circumferential stress (σθ). A detailed parametric study has been executed, and the effects of different input material parameters, namely, geological strength index (GSI), yield parameter (mi), and the disturbance factor (D) on the results have been studied. For different height to radius ratios of the excavation, the computed results are presented in the form of nondimensional stability numbers. Failure mechanisms have also been investigated for a few typical cases. The results from the analysis have been compared with that evaluated separately with the application of the software OptumG2. [ABSTRACT FROM AUTHOR]

Slabbing failure and strain rock burst are the main failure patterns during the excavation and construction phases of deep tunnels in hard and brittle rock, which cause unexpected equipment damage and casualties. This study presents a numerical simulation with an unloading central hole within a hard rock specimen in the laboratory scale. A combined finite element/discrete element method (FEM/DEM) reproduces the crack initiation, propagation, and coalescence around the central hole during the entire failure process. The influence of sectional shapes, unloading rates of holes, and in situ stresses on the failure characteristics and mechanical response of typical hard and brittle rocks were investigated by analysis of the failure pattern, displacement distribution (average velocity) of monitoring elements, and released strain energy value. The numerical results indicate that the sectional shapes, unloading rates, and in situ stresses have a significant impact on the severity of destruction and failure range in hard rock under the excavation unloading conditions. Slabbing failure (stable failure) is always the dominant failure pattern around a circular hole, which shows higher bearing capacities and self‐stabilization. With the increase in unloading rates, more visible cracks are generated around the holes, and the displacement and average velocity of discrete blocks are further raised. This is particularly evident in rock specimens with holes having vertical walls, leading to intense unstable failure (strain rock burst) accompanied by a large amount of strain energy released. In situ stresses affect considerably the stability of the surrounding rock during the excavation unloading process. With constant in situ stress, the order of destruction severity around the central hole according to its sectional shape is cube > trapezoid > U‐shape > ellipse > circle. The destruction intensity is further aggravated with the increase in lateral pressure coefficient, and the failure regions are always observed in the roof and floor of the central hole. This study confirms that strain rock burst tends to be induced in hard and brittle rock tunnels with polygonal roadway section under high unloading rates and lateral pressure coefficients. [ABSTRACT FROM AUTHOR]

Abstract: The extraction of construction material in Addis Ababa has been a source of public conflict for many years, especially in terms of quarry operation, displacement of people, rehabilitation of quarry sites, and land after‐use. One of the main reasons for the conflict has been the extraction sector's inability to adjust to the existing laws. This paper reports the findings of a study undertaken to assess the environmental and socioeconomic impacts of quarry mining in Addis Ababa, Ethiopia, and it prescribes interventions that can assist in mitigating the negative impacts of mining. Marked operational, environmental, and socioeconomic impacts have occurred as a result of cobblestone quarrying in Addis Ababa. Improvements in the mitigation of these impacts can be achieved if quarrying operations are planned prior to commencement; resource‐efficient and sustainable mining techniques are employed; stakeholder participation is enhanced; the government provides institutional, organizational, and technical support to the operators; regulations are improved and regulatory implementations receive strict follow‐up; and the provision of the Ethiopian constitution's regarding “rights to development” is respected. [ABSTRACT FROM AUTHOR]

In the course of constructing the new Vienna - St. Pölten high-speed railway line, three TBM tunnels with an excavated diameter of approx. 13 m were driven between 2005 and 2010. The total length of these three tunnels including portal structures, cut-and-cover and top-down sections was approx. 7.4 km, of which 6.2 km were excavated by TBM-S. The tunnels were constructed with drainage systems and two-pass linings in the tunnel arch. During the feasibility study, the permit application design and the tender design phase, detailed risk analyses were performed for excavation method (TBM or NATM), machine type (TBM-S or SM-EPB) and lining type (single- or two-pass). The expectations of the client during the design phase and those of the contractor during the bidding phase are compared and discussed, taking into account construction time considerations, geotechnical risk assessments, lining design, machine type and construction sequence as well as the allocation of risks between client and contractor. The reality of the project, i.e. the construction time actually needed, the challenges encountered, the problems solved and the joint approach adopted to implement the project as well as the lessons learned (experiences and findings) are all described. Im Zuge der Errichtung der Neubaustrecke Wien - St. Pölten wurden in den Jahren 2005 bis 2010 drei Tunnel mittels einer Tunnelbohrmaschine mit einem Ausbruchsdurchmesser von rund 13 m aufgefahren. Die Gesamtlänge der drei Tunnelbauwerke, inklusive der Portalbauwerke, offenen Bauweisen und Deckelbauweisen, betrug rund 7,4 km, wobei rund 6,2 km mit einer TBM-S aufgefahren wurden. Die Tunnel wurden druckwasserentlastet mit einem zweischaligen Ausbau im Gewölbe hergestellt. Für die Tunnel wurden in den Phasen der Grundsatzprüfung, der Behördenverfahren und der Ausschreibungsplanung vertiefte Risikoanalysen zur Vortriebsmethode (TVM oder NÖT), zur Wahl des Maschinentyps (TBM-S oder SM-EPB) und des Ausbaus (einschalig oder zweischalig) erstellt. Die Erwartungen des Auftraggebers (AG) in der Planungsphase und des Auftragnehmers (AN) in der Angebotsphase werden anhand von Bauzeitüberlegungen, Risikobetrachtungen zu Geotechnik, Ausbau, Maschine und Bauablauf sowie der Sphärenzuordnung AG und AN gegenübergestellt und erläutert. Die Wirklichkeit, also die reale Bauzeit, die aufgetretenen Schwierigkeiten, die gelösten Probleme und die partnerschaftliche Projektabwicklung sowie die gewonnenen Erfahrungen und Erkenntnisse werden dargelegt. [ABSTRACT FROM AUTHOR]

The multi-function station (MFS) Faido, with track crossovers located symmetrically around the transverse cavern, is accessed through a 2.7 km long access tunnel. The geology encountered in the transverse cavern and the first metres of boring the running tunnels was very different from the forecast. Technical, economic and scheduling considerations demanded the moving of the four crossovers by 600 m to the south. In the drill and blast excavation of the single-track tunnel to the north, deformations of up to 1.3 m occurred in the radius. In addition to the dangers of 'squeezing rock' and 'rock fall', unforecast and serious rock burst also occurred in the east and west running tunnels, which could not have been foreseen. Yielding temporary support measures had to be carried out along a length of 500 m and sometimes massively strengthened. Intensive probing in the form of hammer and core drilling and seismic methods (TSP - Tunnel Seismic Prediction) was carried out during the tunnel drives. The drives were also monitored with intensive rock mechanical measurements. The results of probing, the rock mechanical measurements and the interpretations of the encountered geology all confirmed that the decision was correct to move the MFS. Die Multifunktionsstelle (MFS) Faido mit symmetrisch um die Querkaverne angeordneten Spurwechseln ist mit einem 2,7 km langen Zugangsstollen erschlossen. Die angetroffene Geologie in der Querkaverne und den ersten Metern Vortrieb in den Einspurstrecken wichen massiv von der Prognose ab. Technische, wirtschaftliche und programmliche Gründe erforderten eine Verschiebung der vier Spurwechsel um 600 m nach Süden. Im Sprengvortrieb der Einspurtunnel Richtung Norden stellten sich Deformationen von bis zu 1,3 m im Radius ein. Zu den Gefährdungen 'Druckhaftigkeit' und 'Nachbrüchigkeit' kamen nicht prognostizierte starke Bergschlagphänomene in der Ost- und Weströhre hinzu, die nicht vorhergesagt werden können. Die Ausbruchsicherungsmaßnahmen mussten aufgrund der Bergschlagphänomene auf ca. 500 m Länge nachgiebig ausgeführt und zum Teil massiv verstärkt werden. Die Vortriebe wurden von einer intensiven Vorauserkundung in Form von Schlag- oder Kernbohrungen und mit Seismik (TSP - Tunnel Seismik Prediction) begleitet. Zudem wurden die Vortriebe mit intensiven felsmechanischen Messungen überwacht. Die Erkenntnisse aus den Vorauserkundungen, den felsmechanischen Messungen und den Interpretationen der vorgefundenen Geologie bestätigte die Richtigkeit der Entscheidung, die MFS zu verschieben. [ABSTRACT FROM AUTHOR]

The article describes how the great challenge of managing the material excavated during the construction of the Gotthard Base Tunnel was overcome. The recycling of material from mechanized tunnelling as high-grade aggregates and the development of high-quality concrete mixes demanded new methods and set new standards. At the same time, the environmental impact could be considerably reduced and considerable cost savings were achieved. Der Artikel beschreibt wie die großen Herausforderungen gemeistert wurden, die sich beim Bau des Gotthard-Basistunnels bezüglich der Bewirtschaftung des Tunnelausbruchmals stellten. Bezüglich der Herstellung von Ausbruchmaterial aus dem mechanischen Tunnelvortrieb zu hochwertigen Gesteinskörnungen und der Entwicklung von qualitativ hochstehenden Betonmischungen wurden neue Wege beschritten und neue Maßstäbe gesetzt. Gleichzeitig konnten die Umweltbelastungen deutlich reduziert und erhebliche Kosten eingespart werden. [ABSTRACT FROM AUTHOR]

As a potential host rock for deep geological disposal of radioactive waste, the Callovo-Oxfordian and Opalinus clay rocks have been extensively investigated in the laboratory with respect to deformation under various thermo-hydro-mechanical conditions: (1) stresses covering the range from the initial lithostatic state to redistributed levels after excavation, (2) humidity variations representing ventilation during operation of tunnels as well as water migration from the far-field and (3) heating from ambient temperature up to 100 °C and a subsequent cooling phase. For these highly consolidated clay rocks, a new concept is theoretically derived to explain the effective stress in the particle matrix and experimentally confirmed. The mechanical deformation of the clay rocks is determined by means of short- and long-term compression experiments on quasi water-saturated samples at ambient temperature. Reponses of the clay rocks to humidity changes are examined by drying and wetting the samples under different loading conditions. Thermal effects are studied by heating and cooling the stressed samples under drained and undrained conditions. The main findings are presented and discussed in this paper. [ABSTRACT FROM AUTHOR]

Indurated clay formations are under consideration as potential host rock formations for the disposal of radioactive waste in several countries. The favourable features of such formations for deep geological repositories include an excellent hydraulic barrier function, high capacity for dissolved radionuclide retention and considerable self-sealing potential. The development of a brittle fracture network (excavation-induced damage zone, EDZ) around underground structures during construction and operation cannot however be avoided. To assess the impact of the EDZ on long-term safety of the repository, a detailed structural inventory of the fracture network and the relevant hydro-mechanical phenomena and processes during excavation and the subsequent operation phase is required. This then forms the geomechanical basis for the development of conceptual and numerical models of the EDZ. Here we present some empirical and experimental evidence from the Mont Terri Underground Research Laboratory (URL), summarizing the key phenomena and processes associated with the creation and evolution of an EDZ in the Opalinus Clay. In particular, the significance of rock mass anisotropy is highlighted, both as a likely origin for far-reaching pore fluid pressure changes and as a controlling factor in EDZ development during the excavation process. [ABSTRACT FROM AUTHOR]

NFM Technologies has designed and delivered four 6.99 m-diameter Double Shield TBMs that are excavating the North West Rail Link project, an extension to the Sydney rapid transit network. The project is led by a consortium comprising Thiess, John Holland and Dragados, acting on behalf of the Government of New South Wales Transport Authority. Altogether, the TBMs will build 15 km of twin tunnels in rock that is mainly formed of abrasive sandstone. TBMs 1 and 2 bore the 9 km section between the Bella Vista and Cherrybrook stations, while the remaining 6 km from Cherrybrook to the Epping interchange are bored by TBMs 3 and 4. In this paper, we focus on the achieved performance of the 4 TBMs after approximately 50% completion. We analyse their variations in terms of excavation speed and consumption of disc cutters against the geology and geotechnical characteristics along the tunnel route. We discuss the overall production data and specific aspects of this hard rock urban tunnel project. [ABSTRACT FROM AUTHOR]

While image-based face documentation is well established in conventional tunnelling, even photogrammetric 3D reconstruction, this technical aid is not available in mechanized tunnelling. In a research project of the Chair of Subsurface Engineering with Geodata GmbH, work is underway to develop an imaging device, which is mounted in the cutterhead of a TBM and takes pictures during the maintenance shift that can be used for a photogrammetric reconstruction of the face. In the present article, the results of the first test images are presented. These were undertaken on a tunnel boring machine on the ÖBB project Koralm Tunnel KAT2 in agreement with the research initiative of the ÖBB-Infrastruktur AG. Beside the optical imaging of the face, the determination of the load acting on disc cutters is another focus of research at the Chair. The Disc Cutter Load Monitoring (DCLM) system can be used to provide detailed information about the face and its properties affecting excavation with discs, and further forecasts about penetration and tool wear can also be made. The development of the disc cutter load monitoring system is part of the DRAGON project, which is supported by the European Commission under the FP7 Programme. Finally, the small scaled cutting test of the Chair of Subsurface Engineering is presented. This test rig is designed as an addition to conventional hydraulic testing presses and offers the capability of setting penetration and cutting track spacing. The samples used are half cylinders made from drill cores. The first comparison of the test results with those from large-scale cutting tests have shown that the model cutting test delivers results that are well suitable for the forecasting of TBM performance. Während die bildbasierte Ortsbrustdokumentation bis zur photogrammetrischen 3D-Rekonstruktion in konventionellen Vortrieben gut etabliert ist, fehlt es im maschinellen Tunnelbau an diesen Hilfsmitteln. In einem Forschungsprojekt des Lehrstuhls für Subsurface Engineering mit der Geodata GmbH wird an der Entwicklung einer Aufnahmeeinheit gearbeitet, die im Bohrkopf einer TBM montiert wird und in der Wartungsschicht Bilder von der Ortsbrust aufnimmt, die Grundlage einer photogrammetrischen 3D-Rekonstruktion der Ortsbrust bilden. Im vorliegenden Beitrag werden Ergebnisse erster Testaufnahmen präsentiert, die auf einer Tunnelvortriebsmaschine des ÖBB-Projekts Koralmtunnel KAT2 in Übereinstimmung mit der Forschungsinitiative der ÖBB-Infrastruktur AG vorgenommen wurden. Neben der optischen Aufnahme der Ortsbrust ist die Schneidkraftermittlung von Diskenmeißeln ein weiterer Forschungsschwerpunkt des Lehrstuhls. Durch den Einsatz eines Disc Cutter Load Monitoring (DCLM) Systems können detaillierte Aussagen über die Ortsbrust und deren Abbaueigenschaften mit Disken als auch weiterführend Prognosen über die Penetration und den Werkzeugverschleiß getätigt werden. Die Entwicklung des Diskenkraftmesssystems erfolgt im Rahmen des DRAGON-Projekts, das von der Europäischen Kommission im Rahmen des FP7 Programms unterstützt wird. Abschließend wird der Modellschneidversuch des Lehrstuhls für Subsurface Engineering präsentiert. Die Versuchseinrichtung ist als Ergänzung für herkömmliche hydraulische Prüfpressen konzipiert und verfügt über die Möglichkeit zur Einstellung von Penetration und Schneidspurabstand. Als Probekörper dienen Halbzylinder, die aus Bohrkernen hergestellt werden. Erste Vergleiche der Versuchsergebnisse mit jenen von großmaßstäblichen Schneidversuchen haben gezeigt, dass der Modellschneidversuch Ergebnisse liefert, die gut für die TBM Leistungsprognose geeignet sind. [ABSTRACT FROM AUTHOR]

The abrasiveness of crushed rock is determined in the design phase of a tunnelling project to estimate the wear on excavation and boring tools, using for example the LCPC abrasiveness test. Considered from the point of view of material science, there are problems with the validity of such an index value since important tribological factors, like for example the internal structure of the sample impeller (size, phase composition) are not considered in the current testing standard (AFNOR P18-579). In this investigation, LCPC tests were performed with impellers of various steels of the same and different hardnesses against two abrasives (Mohs hardness 7, 9) in order to determine the influence of the internal structure and the associated tribo-mechanical properties on the LCPC index value (ABR). In addition to the material hardness required by the standard (60 to 75 HRB ≈ 105 to 140 HV 10 according to DIN EN ISO 18265-2013), sample materials with higher hardness values were also used in order to extend the basis of the LCPC abrasiveness index to these practically applicable material groups. The results make clear that awareness has to be raised regarding the materials used for the LCPC test. An abrasive can be classified differently just by using various materials of the same hardness. In order to obtain reliable and reproducible index values for the abrasiveness of crushed rock, it is necessary to consider the influence of materials in future recommendations for the LCPC. Die Abrasivität von Lockergestein wird im Rahmen der Planungsphase eines Tunnelbauprojekts zur Abschätzung des Verschleißes an Abbau- und Bohrwerkzeugen bestimmt, beispielsweise durch den LCPC-Abrasivitätstest. Aus werkstofftechnischer Sicht ergeben sich Schwierigkeiten in Bezug auf die Aussagekraft eines solchen Indexwertes, da wichtige tribologische Einflussfaktoren wie z. B. das Gefüge des Prüfflügels (Größe, Phasenzusammensetzung) in der aktuellen Prüfnorm (AFNOR P18-579) nicht berücksichtigt werden. Im Rahmen dieser Untersuchung wurden LCPC-Versuche mit Drehflügeln aus verschiedenen Stählen gleicher und unterschiedlicher Härte gegen zwei Abrasive (Mohshärte 7, 9) durchgeführt, um den Einfluss des Gefüges und den damit verbundenen tribo-mechanischen Eigenschaften der Prüfflügelwerkstoffe auf den LCPC-Indexwert (ABR) zu ermitteln. Neben Werkstoffhärten, die nach Norm gefordert werden (60 bis 75 HRB ≈ 105 bis 140 HV 10 nach DIN EN ISO 18265-2013), fanden auch Prüfwerkstoffe mit höheren Härtewerten Anwendung, um die Datenbasis des LCPC-Abrasivitätsindex auf diese anwendungsnahen Werkstoffgruppen auszuweiten. Die Ergebnisse verdeutlichen, dass eine Sensibilisierung im Umgang mit dem LCPC-Versuch in Bezug auf die verwendeten Werkstoffe erforderlich ist. Ein Abrasiv lässt sich unterschiedlich klassifizieren, nur durch die Nutzung von verschiedenen Werkstoffen derselben Härte. Um aussagekräftige und reproduzierbare Indexwerte für die Abrasivität von Lockergestein bestimmen zu können, ist es notwendig, werkstofftechnische Einflüsse in zukünftigen Empfehlungen für den LCPC-Versuch zu berücksichtigen. [ABSTRACT FROM AUTHOR]

This paper summarizes the main observations related to geotechnical properties and tool changes that characterize the different tunnel drives in a database of 33 km of EPB tunnel records from the Barcelona area. The data have been examined in detail with regard to cutting tool replacement and performance of the mechanized excavation. The database includes tunnels in soft soils, in hard and medium rocks and in mixed soil-rock conditions; tool changing records and geotechnical properties. Transverse and longitudinal geotechnical heterogeneity are accounted for systematically. Longitudinal heterogeneity is used to subdivide the drives in the database into homogeneous units. Transverse (within section) heterogeneity is described by a set of newly developed impact factors FI. [ABSTRACT FROM AUTHOR]

The instantaneous response of saturated low permeability grounds to tunnel excavation is important for deformations and stability close to the tunnel face. It is characterized by zero volume change in combination with the development of excess pore pressures. In tunnelling through poor quality ground under great depth of cover and high in situ pore pressure, heavily squeezing conditions (characterized by very large convergences) may occur soon after excavation. This paper presents exact finite strain analytical solutions for the undrained ground response around cylindrical and spherical openings that are unloaded from uniform and isotropic initial stress states, on the basis of the Modified Cam Clay (MCC) model and the Mohr-Coulomb (MC) model. The solution for a Drucker-Prager material is also given as it requires only a very small modification to the MC solution. The so-called ground response curve, that is, the relationship between the support pressure and the cavity wall displacement, is derived in closed form for the MC model. The solution for the MCC problem is semi-analytical in that it uses the trapezium rule for the computation of a definite integral. The influence of the significant parameters of the problem on the predicted deformation behaviour is shown by means of dimensionless charts. Finally, the practical usefulness of the solutions presented is illustrated by applying them to the breccia zones of the planned Gibraltar Strait tunnel - an extreme case of weak, low permeability ground under high pore pressure. The solutions can serve as a trustworthy benchmark for numerical procedures that incorporate material and geometric nonlinearities. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Failure in geotechnical engineering is often related to tension-induced cracking in geomaterials. In this paper, a coupled meshless method and FEM is developed to analyze the problem of three-dimensional cracking. The radial point interpolation method (RPIM) is used to model cracks in the smeared crack framework with an isotropic damage model. The identification of the meshless region is based on the stress state computed by FEM, and the adaptive coupling of RPIM and FEM is achieved by a direct algorithm. Mesh-bias dependency, which poses difficulties in FEM-based cracking simulations, is circumvented by a crack tracking algorithm. The performance of our scheme is demonstrated by two numerical examples, that is, the four-point bending test on concrete beam and the surface cracks caused by tunnel excavation. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Both the technical boundary conditions and the usual advance rates achieved during hard rock TBM shield drives severely limit the ability of the on-site-personnel to document the geological conditions and the system behaviour at appropriate intervals. A systematic and continuous short-term investigation of the rock mass conditions is performed on the construction lot KAT2 of the Koralm Tunnel (obtained by impact drillings and geophysical methods). The difference in scales and the fact that no continuous inspection of the ground conditions can be performed lead to a gap between the prognosis and the observed behaviour and a direct comparison is seldom possible. Based on the daily comparison between the observed behaviour and the analysed machine data, a state-of-the-art interpretation method has been developed. This method allows reliable conclusions regarding the primary aspects of the system behaviour and thus enables deductions on the geological/geotechnical conditions which have been encountered. The identification of the relevant parameters and suitable analysis methods has been performed in a 'trial and error' manner: machine parameters deemed relevant in theory have been continuously compared with the observations on site and depending on the results, found usable or discarded. Reliable knowledge about the face stability, qualitative degree of fracturing of the rock mass, occurrence of over excavation in the cutter head area, the state of the annular gap and the blockiness of the rock mass can be deduced by applying this method. The results are used on daily basis by the on-site geologist and geotechnical engineer in order to verify the prognosis and recommend additional/auxiliary construction measures. Sowohl die technischen Rahmenbedingungen als auch die üblichen Vortriebsgeschwindigkeiten einer Tunnelvortriebsmaschine mit Schild (TVM-S oder TVM-DS) im Hartgestein beschränken die Fähigkeit des verantwortlichen Personals, die geologisch-geotechnischen Verhältnisse bzw. das Systemverhalten anhand der augenscheinlichen Inspektion und der geotechnischen Messdaten zu erfassen. Da am Baulos KAT2 des Koralmtunnels eine systematische und lückenlose Vorauserkundung betrieben wird, entsteht dadurch eine 'Lücke' zwischen der Prognose (anhand der Bohrungen und/oder der geophysikalischen Methoden) und den beobachteten Verhältnissen. Auf Grundlage bestehender Veröffentlichungen konnten für die täglichen Vergleiche zwischen dem beobachteten Systemverhalten und den analysierten Maschinendaten im Zuge des kontinuierlichen Vortriebs KAT2 ein Verfahren entwickelt werden, das zuverlässige Aussagen über die wesentlichen Aspekte des Systemverhaltens beim kontinuierlichen Vortrieb erlaubt und somit Rückschlüsse hinsichtlich der aufgefahrenen geologisch-geotechnischen Verhältnisse ermöglicht. Die Identifikation der relevanten Parameter und der Auswerteverfahren erfolgte im 'Trial-and-error'-Verfahren: Alle theoretisch relevant erscheinenden Maschinenparameter wurden mit den Beobachtungen vor Ort verglichen und in den endgültigen Satz von aussagekräftigen Parametern aufgenommen bzw. als unbrauchbar verworfen. Zuverlässige Aussagen über die Ortsbruststabilität, den qualitativen Zerlegungsgrad, die Profilmaßhaltigkeit im Bohrkopfbereich, den Zustand des Ringspalts und die Blockigkeit des Gebirges können mit diesem Verfahren getroffen werden. Die Ergebnisse werden täglich von den verantwortlichen Geologen und Geotechnikern verwendet, um die Prognosen zu verifizieren, das Prognosemodell stetig fortzuschreiben und zu verfeinern und nach Erfordernis Zusatz- bzw. Sondermaßnahmen zu empfehlen. [ABSTRACT FROM AUTHOR]

In the planning of tunnels to be excavated according to NATM principles, the decision between full face or partial face excavation is of fundamental and decisive importance for the entire tunnel project. The current paper compares tunnel drives with full face and partial face excavation from various angles. In addition, the influential factors that have to be considered in the decision are explained. Also, an explanation as to how decisions are made in the course of the design, tendering and construction phases is presented. The paper is only concerned with NATM tunnelling; other methods like ADECCO or mechanised tunnelling methods are not considered. Bei Vortrieben, die nach der NÖT aufgefahren werden, ist die Entscheidung zwischen Vollausbruch oder Teilausbruch von grundlegender und entscheidender Bedeutung für das gesamte Tunnelbauprojekt. Der vorliegende Beitrag vergleicht Vortriebe im Vollausbruch und im Teilausbruch aus unterschiedlichen Gesichtspunkten. Zudem wird erörtert, welche Einflussfaktoren bei der Entscheidung berücksichtigt werden sollten und wie die Entscheidungen im Verlauf von Planung, Ausschreibung und Ausführung gefällt werden. Der Beitrag behandelt ausschließlich NÖT-Vortriebe. Andere Bauverfahren wie ADECCO oder maschinelle Vortriebsmethode werden nicht betrachtet. [ABSTRACT FROM AUTHOR]

Am 18. Mai 2013 kam es ca. 600 m vor dem östlichen Tunnelportal zu einem LKW‐Brand in der Südröhre des Tunnels Königshainer Berge. Nach dem Brand waren im Bereich der Unglücksstelle Betonabplatzungen festzustellen. Zur Bewertung des Schädigungsgrads an Tunnelschale, Dichtung, Dränage, Kabelleerrohren, Kappen, Entwässerung, Schlitzrinne, Markierung und Fahrbahn wurden mit dem Ziel der Ableitung von Instandsetzungsmaßnahmen experimentelle Untersuchungen und numerische Berechnungen durchgeführt. Unter Zugrundelegung der ermittelten Brandlast wurde die Temperaturbeanspruchung der Tunnelschale orts‐ und zeitabhängig bestimmt, um mit diesen Informationen das Durchwärmungsverhalten zu berechnen und die statisch‐konstruktiven Auswirkungen auch im Vergleich zu den experimentellen Untersuchungen und Werkstoffprüfungen zu verifizieren. Im Ergebnis der Untersuchungen konnte ein Instandsetzungskonzept für den Konstruktionsbeton abgeleitet und umgesetzt werden. Tunnel Königshainer Berge from fire incident to repair concept On May 18, 2013, a truck fire happened in the southern tube of the Tunnel Königshainer Berge – 600 m before the eastern tunnel portal. After the fire, concrete spalling was observed in the crash area. For the evaluation of the damage degree of tunnel lining, sealing, drainage, cable ducts, sidewalks etc. experimental investigations and numerical calculations have been conducted in order to derive repair measures. On the basis of the evaluated fire load, the temperature loading on the tunnel lining was determined – both site‐ and time‐orientated. These information were used to calculate the temperature ingress and distribution and to verify the static and structural effects in comparison to the experimental investigations and material tests. As a conclusion, a repair concept for the structural concrete was derived and executed. [ABSTRACT FROM AUTHOR]

Im Februar 2009 kam es zu einem Teileinsturz der historischen Stadtmauer Hildburghausen auf einer Länge von ca. 10 m. Als Konsequenz aus dem Einsturz wurde die Sanierung eines erweiterten Areals beschlossen. Diese umfasste die statische Sicherung sowie die Steinrestaurierung der Mauerfassade eines ca. 100 m langen Abschnittes. Der vorliegende Beitrag stellt die Mauerwerksrekonstruktionen im Bereich der Einsturzstellen sowie in weiteren akut einsturzgefährdeten Abschnitten vor. Nahezu das gesamte 5 m hohe Wandmauerwerk wurde mittels Erdverankerungen gegen Umkippen gesichert. Eine Besonderheit bildeten die abschließenden Arbeiten zur Wiederherstellung des eingestürzten Gewölbestollens. Rehabilitation of the lower historic town wall of Hildburghausen - Structural safeguarding and stone restoration. In February 2009 there was a partial collapse of 10 m length of the historic town wall Hildburghausen. As a consequence of the collapse the rehabilitation of an extended area was decided. This included the structural safeguarding and stone restoration of a 100 m long section of the wall façade. The paper describes the masonry reconstructions done in the collapsed area as well as in further sections that were in danger of collapsing. Almost the whole 5 m high wall was secured against tilting by means of soil anchoring. A special feature were the final works of recovering the collapsed tunnel vault. [ABSTRACT FROM AUTHOR]

Motorway tunnelling only started in the Czech Republic after the political changes in Europe in 1989 with the objective of rapidly integrating the then small national motorway network into the European network. In reality, this meant the construction of Motorway D5 to the West (Prague-Pilsen-Nuremberg), Motorway D8 to the North (Prague-Dresden), Motorway D3 to the South (Prague-Budweis-Linz), Motorway D1 to the North-East (Brno/Brün-Ostrava-Katowice), Motorway R52 to the South (Brno/Brün-Vienna) and Motorway R48 (Brno/Brün-Olomouc/Olmütz-Krakow). In order to improving conditions for the rapidly growing traffic around the Czech capital Prague, and to eliminate transit traffic through Prague, an outer motorway was proposed, the Prague City Ring Road R1. In the mean time some of these ambitious plans have been realized and several motorway tunnels constructed in the last decade. The paper starts with a general overview of the motorway tunnels, their parameters and features. The rest is focused on details of the design and construction of the Lochkov Tunnel on the Prague City Ring Road. Der Bau von Autobahntunneln hat in der tschechischen Republik erst nach den politischen Veränderungen in Europa im Jahr 1989 mit dem Ziel begonnen, das damals noch kleine nationale Autobahnnetz in das europäische Netz zu integrieren. In der Praxis bedeutete dies den Bau der Autobahn D5 in Richtung Westen (Prag - Pilsen - Nürnberg), der Autobahn D8 in Richtung Norden (Prag - Dresden), der Autobahn D3 in Richtung Süden (Prag - Budweis - Linz), der Autobahn D1 in Richtung Nordosten (Brno/ Brünn - Ostrava/Ostrau - Katovice/Katowitz), der Autobahn R52 in Richtung Süden (Brno/Brünn - Wien) und der Autobahn R48 (Brno/ Brünn - Olomouc/Olmütz - Krakow/Krakau). Um die Bedingungen für den schnell wachsenden Verkehr rund um die tschechische Hauptstadt Prag zu verbessern und um den Transitverkehr durch Prag zu reduzieren, wurde ein äußerer Autobahnring vorgeschlagen, die Prager Stadtautobahn R1. In der Zwischenzeit sind einige dieser ehrgeizigen Pläne realisiert und mehrere Autobahntunnel gebaut worden. Dieser Artikel beginnt mit einem allgemeinen Überblick über die Autobahntunnel und ihre Kenngrößen und Besonderheiten. Im Weiteren liegt der Fokus auf Details des Entwurfs und Baus des Lochkov Tunnel auf der Prager Stadtautobahn. [ABSTRACT FROM AUTHOR]

Urban road tunnels have only been built in four towns in the Czech Republic. Their purpose is mostly environmental, with construction being enforced by ever growing requirements for environmental protection. Currently there are twelve urban road tunnels operating in the Czech Republic: six in Prague, four in Brno and single tunnels in Liberec and Jihlava. The Blanka complex of tunnels in Prague is currently under construction and will become the longest tunnel in the Czech Republic in 2014. Innerstädtische Straßentunnel wurden bisher nur in vier tschechischen Städten gebaut, und dabei sind meist umwelttechnische Überlegungen ausschlaggebend gewesen. Ihr Bau wurde durchgesetzt aufgrund der immer stärkeren Anforderungen an den Umweltschutz. Zurzeit gibt es in der Tschechischen Republik zwölf städtische Straßentunnel in Betrieb: sechs in Prag, vier in Brünn und jeweils ein Tunnel in Reichenberg und Jihlava. Zusätzlich wird der Blanka Tunnelkomplex in Prag gerade gebaut. Bei Fertigstellung 2014 wird er der längste Tunnel der Tschechischen Republik sein. [ABSTRACT FROM AUTHOR]

We conducted a first-principles examination to determine the most stable position of an icosahedral B12 cluster near a Si(001) surface. We discovered that such a cluster is most stable when its center is located at the fourth layer position from the Si top surface where a Si dimer sits directly overhead. Scanning tunneling microscopy (STM) simulation revealed that Si dimers above the B12 cluster are distinguishable from other dimers in STM images at low sample bias voltages. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(2): 50-56, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10405 [ABSTRACT FROM AUTHOR]

A high degree of cooperation is necessary on every tunnel project. Scarcely any other branch of construction is faced with similar rapidly changing problems. The constantly changing properties of the ground demand the greatest attention and flexibility from all parties. Despite the differing initial positions of the interest groups involved, they have to overcome the complex tasks together. Increasing technical requirements of the project parties are in contrast with the increasing expectations of external stakeholders outside the project. Ever more complicated and extensive contract documents hinder rapid solutions on site for the benefit of the project and lead to a certain loss of ability by the site staff in making appropriate decisions. This unsatisfactory situation can only be countered with mutual understanding and cooperation based on trust. Bei jedem Tunnelprojekt ist ein hohes Maß an Kooperation erforderlich. Kaum eine andere Bausparte wird mit ähnlichen rasch wechselnden Problemen konfrontiert. Die ständig wechselnde Beschaffenheit des Baugrunds fordert von allen Beteiligten höchste Aufmerksamkeit und hohe Flexibilität. Trotz unterschiedlicher Ausgangspositionen der beteiligten Interessensgruppen ist die gemeinsame Bewältigung der komplexen Aufgabe vorgegeben. Steigende fachliche Anforderungen an die Projektbeteiligten stehen den steigenden Erwartungshaltungen projektferner Stakeholder gegenüber. Immer komplizierter und umfangreicher werdende Vertragswerke erschweren rasche und projektgerechte Lösungen von Problemen vor Ort und führen zu einer gewissen Entmündigung des Baustellenpersonals. Diesem unbefriedigenden Zustand kann nur durch eine von gegenseitigem Verständnis und Vertrauen getragene Kooperation begegnet werden. [ABSTRACT FROM AUTHOR]

Characterizing performance of tunnel boring machines (TBM) is important for numerous contractual and technical reasons. A common tool to determine machine performance in the field is the penetration test. The purpose of the penetration test is to operate the TBM for a defined period of time under normalized conditions that allow for interpretation and comparison between tests. The result of a penetration test is a thrust-penetration curve that reflects the excavatability of the rock mass. Prediction models use thrust-penetration curves to calculate the expected performance of a TBM in specific ground conditions. This paper provides a review of recent practice including testing at the Norwegian University of Science and Technology (NTNU) along with research by Villeneuve and Käsling. Each of these methods includes excavation at certain thrust levels and rotational speeds for a certain distance. These existing methods have a number of disadvantages that lead to fairly slow tests, which the proposed methodology aims to eliminate. Für eine Reihe von technischen und vertraglichen Fragestellungen ist die Charakterisierung der Leistung von Tunnelbohrmaschinen (TBM) von Bedeutung. Ein häufig genutztes Werkzeug, um die Bohrleistung einer TBM zu bestimmen, ist der Penetrationstest. Der Zweck eines solchen Tests ist, die TBM für eine gewisse Zeitdauer unter definierten Bedingungen zu betreiben, um so die Vergleichbarkeit zwischen verschiedenen Ergebnissen zu ermöglichen. Das Ergebnis eines Penetrationstests ist eine Penetrations-Kraft-Kurve, die es erlaubt, die Vortriebsleistung einer TBM unter bestimmten Gebirgseigenschaften zu prognostizieren. In diesem Beitrag werden die bisherigen Ansätze der Norwegischen Technischen Universität in Trondheim und Forschungsarbeiten von Villeneuve und Käsling beschrieben. Diesen Ansätzen ist gemein, dass die TBM über eine kleine Vortriebsstrecke bei verschiedenen Vortriebskräften und Bohrkopfdrehzahlen betrieben wird. Die beschriebenen Methoden haben aber auch eine Reihe von Nachteilen, die zu einer relativ langen Testdauer führen. Die hier vorgeschlagene Methode verkürzt die Testdauer bei gleichzeitiger Erzielung höherer Genauigkeit der Ergebnisse. [ABSTRACT FROM AUTHOR]

Full scale linear cutting tests with variable cutter spacing and penetration were conducted on different Alpine lithologies. The analysis focusses on different aspects: First, the investigation of excavated material regarding grain-size distribution curves and aspect ratios. Second, the investigation of cutting forces to better understand rock breakage and the directional dependence of cutting forces in an anisotropic rock mass. A critical view of TBM performance prediction models is also presented. Results show that the percentage of coarse grain is positively correlated with increased cutter spacing, and changing penetration did not result in significant changes of grain-size distribution. Analysis of cutting forces shows that knowledge of cutting forces enables a deeper understanding of rock breakage. Furthermore, it is shown that common performance prediction models are not able to cover certain types of rock satisfactorily. Im Rahmen dieser Arbeit werden Linearschneidversuche mit variablem Schneidspurabstand und Penetration an repräsentativen alpinen Lithologien präsentiert. Das Schwergewicht der Auswertung liegt in der Analyse des Ausbruchmaterials hinsichtlich Sieblinien und Kornform sowie in der Betrachtung der gemessenen Schneidkräfte zum besseren Verständnis des Gesteinsbruchvorgangs, der richtungsabhängigen Kräfte bei anisotropen Gesteinen sowie der kritischen Betrachtung von TBM-Leistungsprognosemodellen. Die Ergebnisse zeigen, dass der Grobkornanteil bei steigendem Schneidspurabstand zunimmt. Die Änderung der Penetration zeigt keinen gravierenden Einfluss auf die Kornsummenkurve. Die Analyse der Schneidkräfte zeigt, dass die Kenntnis von Schneidkräften wertvolle Einblicke in den Gesteinsbruchmechanismus bietet. Als weiteres Ergebnis wird deutlich, dass gängige TBM-Leistungsprognosemodelle die Schneidbarkeit bestimmter Gesteinsarten nicht adäquat vorhersagen können. [ABSTRACT FROM AUTHOR]

ABSTRACT Due to various decay processes associated with weathering, the stability of artificial slopes in weak rocks may be affected well within their envisaged engineering lifetime. Conceptually, the decay following the initial stress release after excavation can be described as a process seeking equilibrium between weathering and erosion. The extent to which such an equilibrium is actually reached influences the outcome of the weathering-erosion decay process as well as the effects that the decay has on the geotechnical properties of the exposed rock mass, and thus ultimately the stability of slopes affected by erosion and weathering. This paper combines two conceptual models for erosion and weathering, and derives a numerical model which predicts the resulting slope development. This can help to predict the development of a slope profile excavated in a weak rock in time, and can be extended with the addition of strength parameters to the weathering profile to enable prediction of slope stability as a function of time. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A whole range of problems are generally associated with the construction of tunnels in weak ground and under high overburden. Among those are large displacements, wide variation of stresses and strains, and sudden water ingress, to name just a few. A wide variety of behaviours can be experienced, depending on the ground conditions and the influencing factors. The contribution deals with experience from the construction of several Alpine tunnels in faulted rock masses. Specific characteristics of each project are highlighted, and the lessons learned described. Eine ganze Reihe von Problemen ist mit Planung und Bau eines Tunnels in Baugrund mit schlechten Eigenschaften und hoher Überlagerung verbunden. Unter anderem sind dies große und stark anisotrope Verformungen oder plötzliche Wassereinbrüche, um nur einige wenige zu nennen. In Abhängigkeit von den Baugrundverhältnissen und den äußeren Einflüssen kann eine ganze Reihe unterschiedlicher Verhalten beobachtet werden. Der Beitrag fasst Erfahrungen zusammen, die beim Bau alpiner Tunnel im gestörten Gebirge gemacht wurden. Spezielle Charakteristika jedes Projekts werden aufgezeigt und die Lehren aus den Erfahrungen mitgeteilt. [ABSTRACT FROM AUTHOR]

The design of a ductile lining has to incorporate a number of influences. Both the influences of the ground conditions and the construction have to be considered in order to develop a safe and economical solution. Special focus has to be set on a plausible prediction of the time- and excavation-dependent displacement development and its interaction with the transient shotcrete properties, load-displacement behaviour of the yielding elements and the entire excavation sequence. The rather underdeveloped state of the state-of-the-art methods for ductile support pre-design is somewhat contrasting the frequent practical usage of this support concept. Especially the development of semi-empirical or analytical methods, allowing a quick initial assessment of the system behaviour and incorporating the influences mentioned above, has been neglected in favour of the numerical analysis methods. A novel calculation method, analogous to the convergence confinement method, applicable to non-circular excavation geometries and unsymmetrical displacement fields is presented in the course of this paper. Castigliano's second law and the associated balance of the outer work enable determining the equilibrium point between the ground and the installed support measures and the determination of the support capacity. Additional semi-empirical relationships, derived from a series of systematic 3D numerical simulations, allow prediction of the pre-relaxation and of the longitudinal displacement profiles for a top heading advance. The combination of these relationships with the proposed energy-based equilibrium criterion allows the establishment of a coherent calculation method, addressing and incorporating all relevant geomechanical and constructional influences. A practical application example and the verification of the method are shown and discussed, with the calculation results compared to the measurement data from the exploratory tunnel Paierdorf (Lavanttal fault system). The same ideas regarding the balance of outer work between the support measures and the rock mass can be used for finding clear boundaries of ground conditions where a flexible support becomes imperative. Die Planung eines duktilen Ausbaus muss eine Vielzahl an Einflüssen berücksichtigen. Sowohl die Gebirgsverhältnisse als auch die bautechnischen Einflüsse sind in dieser Phase zu berücksichtigen, um einen wirtschaftlichen und sicheren Vortrieb zu gewährleisten. Besonderes Augenmerk muss dabei auf eine schlüssige Prognose der zeit- und vortriebsbedingten Verschiebungsentwicklung und deren Wechselwirkungen mit den zeitabhängigen Spritzbetoneigenschaften, Last-Verformungsverhalten der Stauchelemente und der gesamten Vortriebssequenz gelegt werden. Trotz einer Vielzahl an praktischen Erfahrungen mit Vortrieben in verformungsfreudigem Gebirge sind die Berechnungsmethoden zur Vorhersage des Systemverhaltens bei solchen geotechnischen Verhältnissen immer noch teilweise rudimentär. Vor allem die Weiterentwicklung von analytischen Methoden, die eine Vorabschätzung des Systemverhaltens unter Berücksichtigung der oben genannten Einflüsse erlauben, wurde in den letzten Jahren zugunsten numerischer Berechnungsmethoden stark vernachlässigt. In dieser Publikation wird ein neues Rechenverfahren präsentiert, das eine Analogie zum Kennlinienverfahren bei nicht kreisrunden Ausbruchsgeometrien und unsymmetrischen Verschiebungsbildern darstellt. Der zweite Satz von Castigliano und die damit verbundene Bilanz von äußeren Arbeiten des Gebirges und des Ausbaus werden verwendet, um ein Gleichgewicht und die maximale Ausbaukapazität zu bestimmen. Weitere semi-empirische Beziehungen, die aus einer Reihe von numerischen 3DRechnungen hergeleitet wurden, erlauben die Vorhersage der Vorentlastung und der Verschiebungsentwicklung bei einem Kalottenvortrieb. Gemeinsam mit dem neuen Gleichgewichtskriterium ergibt sich ein in sich geschlossenes Rechenverfahren, das alle wesentlichen geotechnischen und bautechnischen Einflüsse erfassen kann. Ein praktisches Anwendungsbeispiel sowie die Verifikation des Verfahrens werden anhand der Verschiebungsmessdaten aus dem Erkundungstunnel (EKT) Paierdorf des Koralmtunnels (Lavanttaler Störungssystem) gezeigt. Die gleichen Überlegungen zur Energiebilanz werden auch zur Bestimmung einer klaren 'Grenze' hinsichtlich Gebirgsverhältnisse, bei denen ein nachgiebiger Ausbau zum Einsatz kommen muss, verwendet. [ABSTRACT FROM AUTHOR]

During the design work for the permit application for the approximately 27.3 km long new Semmering Base Tunnel between Gloggnitz and Mürzzuschlag, it has become apparent that due to its extent, the section through the Graßberg-Schlagl fault system will be more problematic than had been assumed during the route selection process. The article discusses the technical possibilities for the construction of the running tunnels through the fault zone. Support concepts with a second layer of shotcrete and short ring closure are investigated using numerical, timedependent calculations. The time dependence is influenced by the advance-rate and the consolidation of the fault material. The determination of the rock characteristics for the core fault zone is based on triaxial compression tests. Im Zuge der Einreichplanung für den rund 27, 3 km langen Semmering- Basistunnel neu zwischen Gloggnitz und Mürzzuschlag hat sich gezeigt, dass die Durchörterung des Graßberg-Schlagl- Störungssystems aufgrund dessen Ausdehnung schwieriger wird, als im Trassenauswahlverfahren angenommen. Der Beitrag behandelt die technischen Möglichkeiten zur Herstellung der Streckenröhren im Störungsbereich. Dabei werden Ausbaukonzepte mit einer zweiten Spritzbetonschale und kurzem Ringschluss mittels numerischer zeitabhängiger Berechnungen untersucht. Die Zeitabhängigkeit wird durch die Vortriebsgeschwindigkeit und die Konsolidierung des Störungsmaterials beeinflusst. Die Ermittlung der Kennwerte für den Kern-Störungsbereich erfolgt auf Basis von triaxialen Druckversuchen. [ABSTRACT FROM AUTHOR]

This paper deals with the time dependent behaviour and the excavation of deep tunnels in weak rocks. Recent contributions to the formulation of a constitutive model for representing such a behaviour, advanced laboratory testing for parameters identification, and design analysis methods for use in engineering practice are discussed. The Stress Hardening ELasto VIscous Plastic constitutive model (SHELVIP), developed with the intent to analyse the rock mass behaviour of tunnels excavated in severely squeezing conditions in a relatively simple, but complete manner, is presented. Then, an innovative servo controlled triaxial apparatus (HPTA), designed and developed for testing weak rocks, with unconventional features such as accurate measurement systems, advanced mechanical set up, and a relatively high stress working range, both in terms of confining pressure, back pressure and axial load, is presented. Finally, consideration is given to numerical modelling of a tunnel excavated in a severely squeezing rock mass (the Carboniferous Formation along the Lyon-Turin Base Tunnel), where the excavation process has been closely simulated in axisymmetric conditions, and the SHELVIP constitutive model has been introduced. Numerical results are discussed and compared with in situ measurements, in terms of tunnel convergence and stresses in the lining. Dieser Beitrag befasst sich mit dem zeitabhängigen Verhalten und dem Bau von tiefen Tunneln im schwachen Gebirge. Ein kürzlich formuliertes Stoffgesetz, das dieses Verhalten abbildet, fortschrittliche Laborversuchsprozeduren zur Parameteridentifikation und Methoden zur Vorhersage des Systemverhaltens werden diskutiert. Zuerst wird das Stress Hardening ELasto VIscous Plastic (SHELVIP) Stoffgesetz vorgestellt, das mit der Absicht entwickelt wurde, das Gebirgsverhalten von Tunneln in extrem druckhaften Verhältnissen auf eine relativ einfache, aber vollständige Weise zu analysieren. Anschließend wird ein innovativer servo-kontrollierter Triaxialversuchsaufbau, der für Versuche an schwachen Gesteinen entworfen und entwickelt wurde, dargestellt. Der Versuchsaufbau hat unkonventionelle Eigenschaften: Eine relativ breite Variation des Seitendrucks, des Porenwasserdrucks und der Axialspannung ist möglich. Abschließend wird ein praktisches Anwendungsbeispiel der numerischen Analyse bei extrem druckhaften Verhältnissen (Karbonformation im Saint Martin La Porte Zugangsstollen zum Basistunnel Lyon-Turin) gezeigt. Darin wurde der Ausbruchsprozess in einem axialsymmetrischen Modell genau simuliert, unter gleichzeitigem Einsatz des SHELLVIP-Stoffgesetzes. Die Resultate der numerischen Simulation werden diskutiert und mit den Verschiebungsmessdaten hinsichtlich auftretender Tunnelkonvergenzen und Spannungen im Ausbau verglichen. [ABSTRACT FROM AUTHOR]

The article explains the interaction of the overall system of ground, TBM and segment lining based on recent experience of projects using TBMs with active face support in Austria and abroad. The alternating dependencies and their consequences for tunnel construction are discussed in more detail. Of particular interest is the influence of the support medium and how it functions at the face and the tunnel side walls. The interaction of support pressure, thrust force and the centre of gravity of the TBM and its effect on steering behaviour are also considered. The effects of the compression of the segment tube by the TBM (prestress) are considered in relation to the improvement of the bedding and the problem of floating. Der Beitrag beleuchtet die Interaktion des Gesamtsystems 'Untergrund - Tunnelvortriebsmaschine - Tübbingausbau' basierend auf aktuellen Erfahrungen zuletzt realisierter Projekte im In- und Ausland bei TVM-Einsätzen mit aktiver Ortsbruststützung. Dabei wird insbesondere auf die wechselweisen Abhängigkeiten und deren Auswirkungen auf die Tunnelherstellung eingegangen. Ein Schwerpunkt liegt beim Einfluss des Stützmediums und der zugehörigen Wirkungsweise an der Ortsbrust und der Tunnellaibung. Berücksichtigung findet die Wechselwirkung von Stützdruck, Vortriebskraft und der Schwerpunktlage der TVM auf deren Steuerverhalten. Die Auswirkung des Zusammendrückens der Tübbingröhre durch die TVM (Vorspannung) wird in Bezug auf die Bettungsverbesserung und die Problematik des Aufschwimmens betrachtet. [ABSTRACT FROM AUTHOR]

A new method is presented in this paper to pinpoint the origin of white marbles using the chemical analysis of fluids occurring as micro-inclusions in calcitic or dolomitic marbles. Beside the conventional methods usually applied for this purpose, the analyses of significant anions and cations in fluids extracted from white marbles were used to characterize different types of marbles. Using this new approach it is possible to distinguish different groups of marbles which cannot be separated isotopically. A case study was performed on the mausoleum of Belevi, close to Ephesus in Turkey, and the quarries in the area of the mausoleum. The marbles used for the architecture of the mausoleum cannot be distinguished isotopically but were split into two groups when using fluid inclusion analysis. The corresponding quarry for the high-quality marble (cella walls, columns etc.) turned out to be the Kentli Çiftliği quarry, which also supplied the marbles for the classical Artemision. According to the chemical and fluid data it can be shown, however, that neither the adjacent famous antique quarry of Belevi nor the underground mine of Kusini, some 5 km away from the mausoleum, are the sources for the marbles used for the construction or decoration of the mausoleum. [ABSTRACT FROM AUTHOR]

The subsequent clinical course of patients examined in the EMG laboratory has not been adequately studied before. It is not known how EMG findings in practice affect patients’ final diagnosis, treatment and outcome. The aim of the present study was to test the hypothesis that EMG results have an important impact on the choice of patients’ treatment and on outcome. Three years after EMG examination, a short questionnaire asking about initial symptoms, the final diagnosis, treatment and current symptoms was sent to 300 consecutive EMG patients. Responses concerning 186 of them (39% men) were received either from patients and/or from their referring physicians. Information obtained during EMG examination was also added. Data was analyzed using methods of bivariate and multivariate statistics. We found that patients with a pathologic EMG had a better clinical outcome 3 years later. Pathologic EMG has an independent effect, pointing to more favorable disease courses, which was further improved by more active treatment approaches received by these patients. The study demonstrated the important impact of EMG findings on the treatment choice and clinical outcome in population consisting mainly of patients with carpal tunnel syndrome and radiculopathy. Studies in other patient populations are needed. [ABSTRACT FROM AUTHOR]

Nanostructured precursors prepared by ultrasonic aerosol spray pyrolisys at 750–950°C in air were applied for the first time to obtain Ca(Cu,Mn)7O12 colossal magnetoresistance ceramics with a unique submicron necked-grain microstructure. It was observed that a high contribution of intergrain tunneling magnetoresistance results in a 10–20% difference in functional properties as dependent on morphological features of hollow precursor microspheres ASP processed at a given temperature. [ABSTRACT FROM AUTHOR]

A field measurement of fracture compliance is described. The aim was to determine how compliance scales with fracture size and, specifically, how laboratory measurements of fracture compliance compared with field estimates from sonic and seismic data. A test site was constructed, consisting of three 40 m vertical boreholes drilled in the floor of a Carboniferous Limestone quarry. Detailed knowledge of the rocks in the test area was obtained from core analysis, wireline logging and local area fracture mapping. Seismic cross-hole surveys were performed using a sparker source with a dominant frequency of 2000 Hz and hydrophone receivers. The rocks had a compressional-wave velocity anisotropy of 10%, which was attributed to the presence of predominantly horizontal, partially open fractures. Estimates of normal fracture compliance within a range from 2.5 × 10−13 m/Pa to 3.5 × 10−12 m/Pa were obtained from both the cross-hole data and the sonic-log data. This is an order of magnitude greater than values obtained from laboratory experiments which are reported elsewhere. [ABSTRACT FROM AUTHOR]

This contribution presents the preliminary results of the Madain Salih archaeological project, which started in 2001 and which, in December 2004, completed its fourth field season. The aims of this five-year project are a systematic recording of the archaeological remains at the site as well as an analysis of its agricultural potential. The former include not only the tombs, sanctuaries, wells, quarries, walls, buildings, etc., but also the inscriptions written in various scripts and languages. Parallel to this exploration of what is visible on the surface, an extensive geophysical survey was undertaken in the so-called residential area, in the central part of the site, in order to obtain an image of the sub-surface remains. This contribution begins with a presentation of the sources, followed by a brief history of the exploration of Madain Salih. The focus is on the conditions which allowed this project to be established as well as the problematics which guided it. J.-B. Rigot then presents his analysis of the agricultural potential of the site, demonstrating the existence, in antiquity, of a large oasis. Finally, a preliminary description of the main components of the sites: the necropoleis, the sanctuaries and the residential area, is given. [ABSTRACT FROM AUTHOR]