Grouting below Subterranean Water: Erosional Stability Test

The article is focused on the medium-term negative effect of groundwater on the underground grout elements. This is the physical–mechanical effect of groundwater, which is known as erosion. We conduct a laboratory verification of the erosional resistance of grout mixtures. A new test apparatus was designed and developed, since there is no standardized method for testing at present. An erosion stability test of grout mixtures and the technical solutions of the apparatus for the test’s implementation are described. This apparatus was subsequently used for the experimental evaluation of the erosional stability of silicate grout mixtures. Grout mixtures with activated and non-activated bentonite are tested. The stabilizing effect of cellulose relative to erosion stability has been also investigated. The specimens of grout mixtures are exposed to flowing water stress for a certain period of time. The erosional stabilities of the grout mixtures are assessed on the basis of weight loss (WL) as a percentage of initial specimen weight. The lower the grout mixture weight loss, the higher its erosional stability and vice versa.

Ecological and economic basis of anti-erosion stability of forest-agrarian landscapes

The ecological and economic foundations of rational nature management in restoring various kinds of protective forest stands under conditions of severe damage and destruction of wood-shrubby species in the natural-climatic and economic zones of the country were developed. It was determined that using traditional methods of restoration of protective forest plantations in many cases is no longer acceptable due to different levels of damage and substantial changes to economic entities on Earth. However, the main methodological approaches remain. A new methodological approach to restoring forests on the basis of constant adaptation of the existing methodologies for the design and calculation of economic efficiency of new plantings and new ecological-economic conditions and peculiarities has been developed. Certainly ,numerousincorrectly planned forest stands have been created that do not sufficiently fulfill their ecological and economic functions and do not even have a general system of protection of the soil from negative factors. For effective regeneration of plants we have developed a formula for calculating the erosion stability of forest-agrarian landscapes for their optimal recovery through forest shelterbelts. We have developed new features of design and calculation of ecological and economic efficiency of newly created forest ameliorative spaces with new natural-economic conditions for their sustainable regeneration under modern conditions. The transition to environmentally sustainable agriculture of European standards requires fundamentally new solutions to the problem of using forest stands as an organizational component of ameliorative complexes in the context of soil erosion control measures. Soil erosion is one of the main factors of anthropogenic impact on land resources. Intensification of erosion processes leads to substantial degradation of soils, causing great losses to agriculture and generally endangers the safe development of mankind. As long as the process of degradation of the soil continues , the agroecological condition deteriorates and the increased application of mineral and organic fertilizers fails to improve the crop volume , insofar as the crop yield is formed mainly due to the natural soil fertility. In the process of research, we discovered that the expansion of the front intake surface runoff in forestry plantings allows one to increase their effective water-regulative functions. Such an event has a certain practical value, because a large proportion of forest shelterbelts even in satisfactory condition only perform their functionsat 20-30%. Taking into account the indicators of ameliorative-hydrological stress and counter-erosion stability of landscapes in locations of planted forest stands proved to be the most effective method of strengthening the initial contact with runoff ("active") plots .This provides is a unique chance to optimize the ecological economic system of protective forest plantations , especially in newly formed agricultural enterprises under new economic conditions.

Importance of the biofilm matrix for the erosion stability of Bacillus subtilis NCIB 3610 biofilms

Erosion of bacterial biofilms is dependent on the composition of the biofilm matrix and the surrounding chemical environment.

Experimental investigation of reservoir sediments

This study presents an experimental approach to investigate cohesive reservoir sediments. It is shown, how adjacent sediment cores can be extracted from reservoir beds with a Frahm Sediment Sampler. The cores are subsequently used for detailed investigations in a hydraulic laboratory. In a first step, related cores are identified based on their bulk density profiles. One part of the related cores is used to analyze the sediment properties over depth by means of potential stability parameters. The other part is used to determine the depth-dependent erosion stability in an erosion flume (SETEG-system). In the SETEG-system, a photogrammetric method is applied to measure the erosion rates of pre-defined sediment layers at different exposed shear stresses. Subsequently, the critical shear stress can be derived, which leads to an objective evaluation and allows a systematic approach. Finally, both results are combined to investigate possible correlations between the evaluated depth-dependent stability parameters and the measured erosion stability. The approach is presented on sediment cores from the case study “Kleiner Brombachsee”, a reservoir that is located in Middle Franconia, Germany.

Investigation the stability of reservoir sediments in the lab and field

To investigate the erosion stability of reservoir sediments, two measuring strategies were applied. Next to in situ measurements, sediment cores were extracted and analysed in the laboratory. At several sampling points at a reservoir in Germany, the in situ device was used to determine the critical bed shear stresses at the sediment surface. At the same time, sediment cores were withdrawn at each site to perform depth-orientated investigations in the hydraulic laboratory. The objective of this study is to investigate the remobilisation potential of the deposited fine sediments and to compare different methods to determine the erosion threshold. Next to critical shear stresses and erosion rates, additional sedimentary and biological parameters were examined such as bulk densities, particle size distributions, TOC-contents and chlorophylla concentrations. The results show generally a very low erosion stability, especially at the sediment surface and in the upper sediment layers. Deeper sediment layers are characterised by consolidation effects and show a higher erosion resistance. High clay contents result in increased stability while high sand contents show a high remobilisation potential. No significant relation to the parameters TOC-content or chlorophylla concentration are identified. A comparison between the different applied techniques to determine the critical bed shear stresses reveals values in the same order of magnitude; however, some significant variations occur because of different hydromorphological conditions and the different limitations for each device.

Fuzzy Comprehensive Assessment Stability of Vegetated Slope with 3D Geomat Protection Using Cloud Model

Based on the analysis of the classification criteria from various factors,a comprehensive evaluation system of the erosion stability of the vegetated eco-slope protected by 3D geomat is established. To solve the problem of uncertainty in the slope erosion stability analysis and consider the feature of both of random and fuzziness, the theory of Cloud Model has been applied into comprehensive evaluation to realize the uncertainty conversion between the qualitative concept and the quantitative data. By constructing the qualitative rule generator, the specific score of the evaluation index is determined according to the uncertain reasoning. The weights of the evaluation indexes are determined with the help of the Analytic Hierarchy Process developed by Cloud Model (CM-AHP), and then the overall score of the comprehensive evaluation system is obtained. The results of engineering examples demonstrate the practicability and effectiveness of the assessment model, which provides a new way for the evaluation of the erosion stability of the vegetated eco-slope protected by the 3D geomat.