@article{ChenSchwingKarlovšeketal.,
  author    = {Chen, Zhen and Schwing, Moritz and Karlovšek, Jurij and Wagner, Norman and Scheuermann, Alexander},
  title     = {Broadband Dielectric Measurement Methods for Soft Geomaterials: Coaxial Transmission Line Cell and Open-Ended Coaxial Probe},
  series = {International Journal of Engineering and Technology},
  volume    = {2014},
  journal   = {International Journal of Engineering and Technology},
  number    = {volume 6, number 5},
  doi       = {10.7763/IJET.2014.V6.728},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210408-43984},
  pages     = {373 -- 380},
  abstract  = {Broadband dielectric measurement methods based on vector network analyzer coupled with coaxial transmission line cell (CC) and open-ended coaxial probe (OC) are simply reviewed, by which the dielectric behaviors in the frequency range of 1 MHz to 3 GHz of two practical geomaterials are investigated. Kaolin after modified compaction with different water contents is measured by using CC. The results are consistent with previous study on standardized compacted kaolin and suggest that the dielectric properties at frequencies below 100 MHz are not only a function of water content but also functions of other soil state parameters including dry density. The hydration process of a commercial grout is monitored in real time by using OC. It is found that the time dependent dielectric properties can accurately reveal the different stages of the hydration process. These measurement results demonstrate the practicability of the introduced methods in determining dielectric properties of soft geomaterials.},
  subject      = {Impedanzspektroskopie},
  language  = {en}
}
@misc{NawazKhan,
  author    = {Nawaz Khan, Shah},
  title     = {Numerical analysis of deformation and stability in the formation for railway tracks},
  doi       = {10.25643/bauhaus-universitaet.3786},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180907-37867},
  abstract  = {Over the past few decades, the increasing demands of railways operations in the form of heavy loading and high speed have been noticed. Railway formation and ballast deform progressive under heavy axle cyclic loading, therefore the rail track needs proper design of ballast and formation bed to achieve the desire stiffness and stability for the safe and sound serviceability of the track. For the overall stability of the track on soft formation, the ground is improved by different techniques prior to the construction on that, in order to avoid the failure and differential settlement during the designed trains operation. The numerical analyses illustrate that the total deformation and bearing capacity of the railway tracks mostly depend on the changes in the friction angle and cohesion of the selected soils of the subgrade. To avoid failure in the formation of track under the design loads, the proper selection of types of soils, its layer thickness, well compaction during construction and provision of proper track drainage system are extremely important. For the construction of new railway tracks the soils having greater values of friction angle, cohesion and elastic stiffness with the well graded ballast cushion under the sleepers of designed side slopes can be used to reduce the maintenance cost, considerably increase the life time of the components of the tracks and ultimately give better performance of the tracks.},
  subject      = {Eisenbahnstrecke},
  language  = {en}
}
@phdthesis{Seiffarth,
  author    = {Seiffarth, Torsten},
  title     = {Sorptionsverhalten von Cu2+ und NH4+ an Bentoniten unter Ber{\"u}cksichtigung von Nebengemengteilen sowie Struktur{\"a}nderungen nach moderater W{\"a}rmebehandlung},
  doi       = {10.25643/bauhaus-universitaet.1979},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130718-19791},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {133},
  abstract  = {Bentonite sind quellf{\"a}hige Tone, die h{\"a}ufig in der Umwelttechnik (in Abdichtungsbauwerken oder in der Bodensanierung) eingesetzt werden. Ziel der Arbeit war die Kl{\"a}rung, wie eine unterschiedliche Kationenbelegung mit Cu2+ und NH4+ die Eigenschaften der Bentonite bei Raumtemperatur und nach moderater W{\"a}rmebehandlung (300 - 450°C) beeinflusst. Im Blickpunkt stand insbesondere die gleichzeitige Pr{\"a}senz von Kupfer- und Ammoniumionen, die als Vertreter f{\"u}r h{\"a}ufig auftretende Inhaltsstoffe von W{\"a}ssern in der Umgebung von technischen Bentoniten ausgew{\"a}hlt wurden. Die Untersuchungen zur Cu2+-Sorption bei Raumtemperatur und nach moderater W{\"a}rmebehandlung (300 - 450°C) erfolgten an Pulverproben von zwei technischen Bentoniten, die sich in der urspr{\"u}nglichen Kationenbelegung, Art und Anteil an Nebengemengteilen, sowie der Schichtladungsverteilung in den Montmorilloniten unterscheiden. Vor der W{\"a}rmebehandlung wurden die Bentonite durch Kontakt mit verschieden konzentrierten Kupfer- und Ammoniuml{\"o}sungen mit unterschiedlichen Gehalten der Kationen Cu2+, NH4+, Na+, Ca2+, Mg2+ belegt. Der Eintrag von Kupferionen in die Bentonite durch Kationenaustausch bei Raumtemperatur wurde erwartungsgem{\"a}ß durch pr{\"a}sente Nebengemengteile (wie Carbonat) beeinflusst, so dass die Kupferionen zus{\"a}tzlich spezifisch adsorbiert und in festen Phasen angereichert wurden. Die Cu2+-Fixierung infolge der W{\"a}rmebehandlung wurde vom Cu2+-Totalgehalt in den Bentoniten, der Pr{\"a}senz von Nebengemengteilen und die Schichtladungsverteilung in den Montmorilloniten beeinflusst. Es waren generell Behandlungstemperaturen von > 400°C erforderlich, um Cu2+-Fixierungsraten von > 95\% zu erzielen. Waren w{\"a}hrend der W{\"a}rmebehandlung neben Cu2+-Ionen gleichzeitig NH4+-Ionen in den Bentoniten pr{\"a}sent, konnte die Cu2+-Fixierungstemperatur herabgesetzt werden. Die Deammonisierung (NH4+ --> NH3 + H+) der NH4+-belegten Bentonite fand gr{\"o}ßtenteils unterhalb der Dehydroxylierungstemperatur der Bentonite statt. Durch Untersuchungen (XRD, FTIR, NMR, ESR) zum Mechanismus der Cu2+-Einbindung in die Bentonite an speziell aufbereiteten Proben (carbonatfrei, < 2 µm) konnte nachgewiesen werden, dass in den Cu2+-belegten Montmorilloniten die Cu2+-Ionen infolge der W{\"a}rmebehandlung nicht bis in die Oktaederschicht der Tonminerale vordringen, sondern nur bis in die Tetraederschicht wandern. In den NH4+-belegten Montmorilloniten treten im Zusammenhang mit der Deammonisierung keine zus{\"a}tzlichen Struktur{\"a}nderungen (wie Aufl{\"o}sung der Oktaederschicht) infolge der W{\"a}rmebehandlung auf.},
  subject      = {Bentonit},
  language  = {de}
}
@article{LorekWagner,
  author    = {Lorek, Andreas and Wagner, Norman},
  title     = {Supercooled interfacial water in fine grained soils probed by dielectric spectroscopy},
  series = {Cryosphere},
  journal   = {Cryosphere},
  doi       = {10.5194/tc-7-1839-2013},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170516-31840},
  pages     = {1839 -- 1855},
  abstract  = {Water substantially affects nearly all physical, chemical and biological processes on the Earth. Recent Mars observations as well as laboratory investigations suggest that water is a key factor of current physical and chemical processes on the Martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid-like state of water on Martian analogue soils for temperatures below 0 °C. To this end, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine-grained soils in the frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to -70 °C. Two Martian analogue soils have been investigated: a Ca-bentonite (specific surface of 237 m2 g-1, up to 9.4\% w / w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g-1, up to 7.4\% w / w). Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak high-frequency processes (bound or hydrated water as well as ice) and a strong low-frequency process due to counter-ion relaxation and the Maxwell-Wagner effect. To characterize the dielectric relaxation behaviour, a generalized fractional dielectric relaxation model was applied assuming three active relaxation processes with relaxation time of the ith process modelled with an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid-like water content by means of the Birchak or CRIM equation. There are evidence that bentonite down to -70 °C has a liquid-like water content of 1.17 monolayers and JSC Mars 1 a liquid-like water content of 1.96 monolayers.},
  subject      = {Grundwasser},
  language  = {en}
}
@phdthesis{Zhu,
  author    = {Zhu, Pengtao},
  title     = {The Variability of the Void Ratio of Sand and its Effect on Settlement and Infinite Slope Stability},
  doi       = {10.25643/bauhaus-universitaet.3741},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180403-37411},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {164},
  abstract  = {The uncertainty of a soil property can significantly affect the physical behavior of soil, so as to influence geotechnical practice. The uncertainty can be expressed by its stochastic parameters, including the mean, the standard deviation, and the spatial correlation length. These stochastic parameters are regarded as constant value in most of the former studies. The main aim of this thesis is to prove whether they are depth-dependent, and to evaluate the effect of this depth-dependent character on both the settlement and the infinite slope stability during rainwater infiltration. A stochastic one-dimensional settlement simulation is carried out using random finite element method with the von Wolffersdorff hypoplastic model, so as to evaluate the effect of stress level on the stochastic parameters of void ratio related parameters of sand. It is found that these stochastic parameters are both stress-dependent and depth-dependent. The non-stationary random field, considering the depth-dependent character of these stochastic parameters, can be generated through the distortion of the stationary random field. The one-dimensional settlement analysis is carried out to evaluation the effect of the depth-dependent character of the stochastic parameters of void ratio on the strain. It is found that the depth-dependent character has low effect on the strain. The deterministic analysis of infinite slope stability during rainwater infiltration is simulated. The transient seepage is carried out using finite difference method, while the steady state seepage is simulated using the analytical solution. The saturated hydraulic conductivity (ks) is taken as the only variable. The results show that the depth-dependent ks has a significant influence on the stability of the slope when the negative flux is high. Without considering the depth-dependent character, can overestimate the factor of safety of the slope. A slope can fail if the depth-dependent character is considered, while it is stable if the depth-dependent character is neglected. The failure time of the slope with a greater depth-dependent ks is earlier during transient infiltration. Meanwhile, the stochastic infinite slope stability analysis during infiltration, is also carried out to highlight the effect of the depth-dependent character of the stochastic parameters of ks. The results show that: the probability of failure is significantly increased if the depth-dependent character of mean is considered, while, it is moderately reduced if the depth-dependent character of the standard deviation is accounted. If the depth-dependent character of both the mean and standard deviation of ks is considered, the depth-dependent mean value plays a dominant influence on the results. Furthermore, the depth-dependent character of the spatial correlation length can slightly reduce the probability of failure.},
  subject      = {Bodenunruhe},
  language  = {en}
}