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  • MDPI AG  (4)
  • Gerke, Horst  (4)
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  • MDPI AG  (4)
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  • 1
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Geosciences Vol. 8, No. 10 ( 2018-09-20), p. 356-
    In: Geosciences, MDPI AG, Vol. 8, No. 10 ( 2018-09-20), p. 356-
    Abstract: The effects of compaction on soil shrinkage behavior need to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a new three-dimensional laser scanning device was coupled with a mathematical-empirical model to simultaneously determine the shrinkage behavior of a boulder marl (bm) and a marsh clay (mc). Therefore, both materials were precompacted in 200 soil cores (100 cm3) on the basis of the Proctor test results with five different degrees of compaction (bm1-bm5; mc1-mc5). Thus, the shrinkage behavior, intensity, and tendency were determined during a standardized drying experiment. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and was classified as high to very high (11.3–17.7%) for the marsh clay and medium (5.3–9.2%) for the boulder marl. Additionally, only the boulder marl (bm2), compacted up to 88% of Proctor density, could be installed as landfill bottom liner in drier locations if the local matric potentials did not exceed the previously highest observed drying range (i.e. values below −300 hPa), to avoid crack formation and generation.
    Type of Medium: Online Resource
    ISSN: 2076-3263
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655946-8
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  • 2
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Geosciences Vol. 8, No. 10 ( 2018-10-10), p. 372-
    In: Geosciences, MDPI AG, Vol. 8, No. 10 ( 2018-10-10), p. 372-
    Abstract: Mineral temporary capping systems of landfills are required to accomplish the long-term coverage prerequisites or to use them as a basis layer prior to later permanent sealing. Such a capping system for a municipal waste landfill in Rastorf (Northern Germany) was developed and tested for its sealing capability on the basis of observed and simulated water balance components for the period between 2008 and 2015, considering observed local weather data and complemented by the Hydraulic Evaluation of Landfill Performance (HELP 3.95 D) model. The modeling results of this case study could be improved by the correction of previously used global solar radiation data due to the consideration of exposure and inclination angle of landfill surface areas. The model could positively be validated by comparing observed and simulated outflow (surface runoff and lateral drainage) data with R2 values ranging between 0.95 and 0.99, as well as for the leachate rates with R2 values of 0.78–0.87. The statistical-empirical HELP model was found useful in predicting the leachate generation of a temporary landfill capping system for specific soil and site conditions, even if only a restricted set of observed data was available.
    Type of Medium: Online Resource
    ISSN: 2076-3263
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655946-8
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  • 3
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Sustainability Vol. 10, No. 11 ( 2018-11-02), p. 4025-
    In: Sustainability, MDPI AG, Vol. 10, No. 11 ( 2018-11-02), p. 4025-
    Abstract: The soil shrinkage behavior of mineral substrates needs to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a novel three-dimensional laser scanning device was coupled with (a) a mathematical-empirical model and (b) in-situ tensiometer measurements as a combined approach to simultaneously determine the shrinkage behavior of a boulder marl, installed as top and bottom liner material at the Rastorf landfill (Northern Germany). The shrinkage behavior, intensity, and geometry were determined during a drying experiment with undisturbed soil cores (100 cm3) from two soil pits; the actual in-situ shrinkage was also determined in 0.2, 0.5, 0.8, and 1.0 m depth by pressure transducer tensiometer measurements during a four-year period. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and it was classified as low (4.9%) for the bottom liner. The in-situ matric potentials in the bottom liner ranged between −100 and −150 hPa, even during drier periods, thus, the previously highest observed drying range (pre-shrinkage stress) with values below −500 hPa and −1000 hPa was not exceeded. Therefore, the hydraulic stability of the bottom liner was given.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2518383-7
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  • 4
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Geosciences Vol. 9, No. 1 ( 2018-12-20), p. 1-
    In: Geosciences, MDPI AG, Vol. 9, No. 1 ( 2018-12-20), p. 1-
    Abstract: Mineral landfill liners require legally-fixed standards including a sufficiently-high available water capacity (AWC) and relatively low saturated hydraulic conductivity values (Ks). For testing locally available and potentially suitable materials with respect to these requirements, the soil hydraulic properties of boulder marl (bm) and marsh clay (mc) were investigated considering a defined compaction according to Proctor densities. Both materials were pre-compacted in 20 soil cores (100 cm3) each on the basis of the Proctor test results at five degrees of compaction (bm1–bm5; mc1–mc5) ranging between 1.67–2.07 g/cm3 for bm and 1.09–1.34 g/cm3 for mc. Additionally, unimodal and bimodal models were used to fit the soil water retention curve near saturation and changes in the pore size distribution (PSD). The structural peak of the PSD in the fraction of pore volume between −30 and −60 hPa was more pronounced on the dry side (bm1–2, mc1–2) than on the wet side of the Proctor curve (bm4–5, mc4–5). Therefore, the loss in structural pores can be attributed to an increasing dry bulk density for bm and an increasing gravimetric moisture content during Proctor test for mc. While the mc fulfils the legal standards with AWC values between 0.244–0.271 cm3/cm3, the Ks values for bm between 1.6 × 10−6 m/s and 3.8 × 10−7 m/s and for mc between 7.4 × 10−7 m/s and 1.2 × 10−7 m/s were up to two orders of magnitude higher than required. These results suggest that the suitability of both materials as landfill liner is restricted.
    Type of Medium: Online Resource
    ISSN: 2076-3263
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655946-8
    Location Call Number Limitation Availability
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