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Strength, deformability and permeability of kakiritic rocks from the Gotthard base tunnel

Journal of Rock Mechanics and Geotechnical Engineering 2023年第9期15卷 2224-2237页

作者： Martin Vogelhuber erich pimentel Georgios Anagnostou ETH Zurich ZurichSwitzerland

The 57-km long,new Gotthard Base Tunnel(GBT)crosses over a 1.1-km long stretch containing kakirites,*** rocks which,depending on the degree of tectonisation,may exhibit severe squeezing behaviour upon tunnel *** tunnel stretch was already identified as a key problem in the early planning phase,necessitating intensive geological exploration and laboratory investigations over a 14-year period,including research and development in experimental *** laboratory investigations for the GBT provided not only a considerable amount of data about the geotechnical parameters of the kakirites,but also valuable information about their basic behaviour and the adequacy of various testing techniques for this type of ***,by using specially designed testing equipment and procedures,it was shown that,(1)conventional rock mechanics triaxial tests cannot provide reliable results for kakirites;(2)the kakirites obey the principle of effective stress in Terzaghi’s classical form and consequently it is indispensable to measure the pore pressure during triaxial testing,analogously to the consolidated drained(CD)and consolidated undrained(CU)tests in soil mechanics;(3)the effects of a possible loss of water and desaturation during sampling,transport,storage and preparation of specimens can be successfully mitigated by subjecting the specimens to flow-through before the actual triaxial testing;and,(4)CD tests on partially saturated specimens that are obtained by means of flow-through can provide reliable and reproducible *** saves a significant amount of time,allows a greater number of tests to be performed,and allows results to be obtained more quickly,which is particularly important for decision-making during tunnel advance.

关键词： Squeezing Pore pressure Triaxial testing

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Using coalgebras and the Giry monad for interpreting game logics a tutorial

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Frontiers of Computer Science 2017年第6期11卷 948-970页

作者： Ernst-erich DOBERKAT Math++ Software Bochum 44879 Germany

The stochastic interpretation of Parikh＇s game logic should not follow the usual pattern of Kripke models, which in turn are based on the Kleisli morphisms for the Giry monad, rather, a specific and more general approach to proba- bilistic nondeterminism is required. We outline this approach together with its probabilistic and measure theoretic basis, in- troducing in a leisurely pace the Giry monad and its Kleisli morphisms together with important techniques for manipu- lating them. Proof establishing specific techniques are given, and pointers to the extant literature are provided. After working through this tutorial, the reader should find it easier to follow the original literature in this and related areas, and it should be possible for her or him to appreciate measure theoretic arguments for original work in the areas of Markov transition systems, and stochastic effectivity func- tions.

关键词： coalgebras modal logics monads Giry monad,upper closed monad composition of monads game logics

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Plasma Spray Forming of Nanostructured Composite Coatings

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Journal of Materials Science & Technology 2002年第3期18卷 287-288页

作者： XianliangJIANG erich.Jordan 等 InstituteofSurfaceandCoatingsTechnology CentralSouthUniversityChangsha410083China InstituteofMatrialsScience UniversityofConnecticutStorrsCT06269USA

The nanostructure composite coating is obtained via plasma spraying of Al2O3-13 wt pct TiO2 powder. Brittle and hard lamella results from melted nanostructured powder. Ductile nanostructured matrix forms from unmelted nanostructured particles. Through the adjustment of constituent and nanostructure, hardness/strength and toughness/ductility are balanced and overall properties of the structure composite are achieved.

关键词： Plasma spray forming Nanostructured coating Mechanical Property

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A NOTE ON PRESSURE APPROXIMATION OF FIRST AND HIGHER ORDER PROJECTION SCHEMES FOR THE NONSTATIONARY INCOMPRESSIBLE NAVIER-STOKES EQUATIONS

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Journal of Computational Mathematics 2009年第2期27卷 338-347页

作者： erich Carelli Andrcas Prohl Mathematisches Institut Universitt TübingenAuf der Morgenstelle 10D-72076 Tübingen

Projection methods are efficient operator-splitting schemes to approximate solutions of the incompressible Navier-Stokes equations. As a major drawback, they introduce spurious layers, both in space and time. In this work, we survey convergence results for higher order projection methods, in the presence of only strong solutions of the limiting problem; in particular, we highlight concomitant difficulties in the construction process of accurate higher order schemes, such as limited regularities of the limiting solution, and a lack of accurate initial data for the pressure. Computational experiments are included to compare the presented schemes, and illustrate the difficulties mentioned.

关键词： Incompressible Navier-Stokes equation Time discretization Projection method

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A combined method to model grain crushing with DEM

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Geoscience Frontiers 2020年第2期11卷 451-459页

作者： Jia Lin erich Bauer WeiWu Institute of Geotechnical Engineering University of Natural Resources and Life SciencesViennaAustria Institute of Applied Mechanics Graz University of TechnologyGrazAustria

This paper presents a combined method to model grain crushing effects with discrete element *** method combines the two most commonly used concepts to model grain crushing in DEM,*** replacement method and the agglomerate method,so that it is both accurate and *** method can be easily *** performance is shown by several DEM simulations of biaxial *** with different crush-abilities are *** simulation results with and without grain crushing are compared and *** change of grain size distribution due to grain crushing is also investigated.

关键词： Grain crushing Discrete element method Granular material

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Prospects and challenges of silicon/germanium on-chip optoelectronics

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Frontiers of Optoelectronics 2010年第2期3卷 143-152页

作者： erich KASPER Institute of Semiconductor Engineering University of Stuttgart

On-chip optoelectronics allows the integration of optoelectronic functions with microelectronics. Recent advances in silicon substrate fabrication(silicon-oninsulator（SOI）) and in heterostructure engineering（SiGe/Si） push this field to compact（chipsize） waveguide systems with high-speed response（50-GHz subsystems realized, potential with above 100 GHz）. In this paper, the application and requirements, the future solutions, the components and the physical effects are discussed.A very high refractive index contrast of the waveguide Si-core/SiO2-cladding is responsible for the submicron line widths and strong bendings realized in chipsize waveguide lines and passive devices. The SiGe/Si heterostructure shifts the accessible wavelength into infrared up to telecommunication wavelengths 1.30–1.55 μm. Germanium, although also an indirect semiconductor as silicon,offers direct optical transitions which are only 140 meV above the dominant indirect one. This is the basic property for realizing high-speed devices for future above 10 GHz on-chip clocks and, eventually, a laser source monolithically integrated on the Si substrate.

关键词： optoelectronics semiconductor circuit silicon germanium silicon-on-insulator (SOI) photodetector modulator waveguide quantum confined Stark effect (QCSE)

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Performance and safety in elite skiing sports:A big challenge on specificity,individuality,and complexity

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Journal of Sport and Health Science 2018年第4期7卷 379-380页

作者： erich Muller Yu Liu Department of Sport Science and Kinesiology University of SalzburgSalzburg A-5020Austria Key Laboratory of Exercise and Health Sciences of Ministry of Education Shanghai University of SportShanghai 200438China

Winter sports, including those with a focus on gliding with skis on snow, have become extremely complex in the last few decades. During the Olympic Games held in Pyeongchang, Republic of Korea, in 2018, a greater number of different skiing competitions took place： alpine skiing with giant slalom, downhill, slalom, and super-G and alpine combined; biathlon with 10-km sprint, 12.5-km pursuit, 15-km mass start, 20-km individual, and a 4×7.5-km relay; cross-country skiing with 6 different kinds of races including short, medium and long distances, classical and skating techniques, and individual and mass start; free-style skiing with aerials, moguls, ski cross, ski halfpipe, and ski slopestyle; Nordic skiing combined with ski jumping on large and normal hills, followed by cross-country skiing over 10 km; and snowboard with big air, half pipe, parallel giant slalom, slope style, and snowboard cross.

关键词：滑雪运动复杂性特性安全性能个性冬季运动滑雪板

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Damage due to rolling in total knee replacement-The influence of tractive force

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Friction 2013年第2期1卷 178-185页

作者： Markus AWIMMER Lars BIRKEN Kay SELLENSCHLOH erich SCHNEIDER Section of Tribology Rush University Medical CenterChicagoIL 60612USA Section of Biomechanics Hamburg University of TechnologyHamburg21071Germany

The femoral condyles of a knee prosthesis articulate with a combination of rolling and sliding on the tibial polyethylene *** is known about potential polyethylene damage due to rolling *** rolling does not exclude the presence of tangential surface loads,this study sought to investigate the influence of tractive rolling on the wear of polyethylene.A“wheel-on-flat”apparatus,consisting of a metal wheel and a polyethylene flat,mimicked contact conditions present in total knee *** increasingly tractive force under conditions of pure rolling was *** was found that under rolling kinematics a tangential surface load of up to 17%of the normal load could be transferred through the *** damage was dependent on the amount of tractive force and appeared more severe with higher *** the region of highest tractive force,wear features were identified that resembled perpendicular ridges on surfaces of retrieved tibial polyethylene *** suggests that tractive rolling may be a relevant wear mode in total knee replacement.

关键词： polyethylene wear knee prosthesis tractive rolling

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Numerical stress-deformation analysis of cut-off wall in clay-core rockfill dam on thick overburden

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Water Science and Engineering 2016年第3期9卷 219-226页

作者： Si-hong Liu Liu-jiang Wang Zi-jian Wang erich Bauer College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Zhejiang Design Institute of Conservancy and Hydroelectric Power Hangzhou 310002China Institute of Applied Mechanics Graz University of TechnologyGraz 8010Austria

The cut-off wall in a clay-core rockfill dam built on a thick overburden layer is subjected to a large compressive pressure under the action of the loads such as the dead weight of both the dam and the overburden layer, the frictional force induced by the differential settlement between the cut-off wall and surrounding soils, and the water pressure. Thus, reduction of the stress of the cut-off wall has become one of the main problems for consideration in engineering design. In this paper, numerical analysis of a core rockfill dam built on a thick overburden layer was conducted and some factors influencing the stress-strain behaviors of the cut-off wall were investigated. The factors include the improvement of the overburden layer, the modeling approach for interfacial contact between the cut-off wall and surrounding soils, the modulus of the cut-off wall concrete, and the connected pattern between the cut-off wall and the clay core. The result shows that improving the overburden layer,selecting plastic concrete with a low modulus and high strength, and optimizing the connection between the cut-off wall and the clay core of the dam are effective measures of reducing the deformations and compressive stresses of the cut-off wall. In addition, both the Goodman element and the mud-layer element are suitable for simulating the interfacial contact between the cut-off wall and surrounding soils.

关键词： Overburden layer Core rockfill dam Cut-off wall Numerical analysis Stress and deformation analysis

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Calibration and performance of two different constitutive models for rockfill materials

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Water Science and Engineering 2016年第3期9卷 227-239页

作者： Lin-ke Li Zhan-jun Wang Si-hong Liu erich Bauer Institute of Applied Mechanics Graz University of Technology Changjiang Institute of Survey PlanningDesign and Research College of Water Conservancy and Hydropower Engineering Hohai University

In this paper, two different concepts for the constitutive modeling of the mechanical behavior of creep-sensitive rockfill materials are presented. Specifically, the performance of an extended generalized plasticity model proposed by Wang is compared with a simplified version of the hypoplastic constitutive model for weathered rockfill materials proposed by Bauer. Both models can reflect the influence of the mean stress on the incremental stiffness, the peak friction angle, and the dilatancy angle. The so-called solid hardness defined for a continuum description and originally introduced by Bauer is embedded in both models. Hydrochemical, thermal, and mechanical weathering are usually caused by environmental changes and are taken into account in a phenomenological description with an irreversible and time-dependent degradation of the solid hardness. A degradation of the solid hardness is usually accompanied by creep deformation of the stressed rockfill material. It is shown that appropriate modeling of creep deformation requires at least a unified description of the interaction between the time-dependent process of degradation of the solid hardness and the stress state. In this context, the solid hardness can be understood as a key parameter for describing the evolution of the state of weathering of the rockfill material. Particular attention is also paid to the necessary procedure for determining the constitutive constants of the two different constitutive models. Finally, the performance of the two different constitutive models is demonstrated by comparing the results obtained from numerical simulations with experimental data from the creep-sensitive rockfill material.

关键词： Rockfill material Creep Generalized plasticity Hypoplasticity Constitutive model

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