Numerical investigation of the performance of engineered barriers in controlling stormwater runoff

In this paper, 2-dimensional, hydro-mechanically coupled finite element analyses are conducted to assess the performance of an engineered barrier, constructed from natural geomaterials, aimed at reducing flood risk in urban environments. The barrier consists of an unsaturated compacted soil layer with water holding properties and a drainage layer of a coarse granular material, that acts as a capillary break, and is constructed on top of the natural soil, in this case London clay. The barrier is vegetated so that its water storage capacity is renewed after each rainfall event. Sophisticated boundary conditions are used to simulate the effect of precipitation and evapotranspiration. The evolution of the rainfall infiltration and runoff rate is simulated both for a treated soil column with an engineered barrier and an untreated one consisting solely of in-situ London Clay. The percolation rate of rainfall water from the bottom of the barrier is also estimated. This comparison highlights the effectiveness of the engineered barrier in reducing the risk of fast flooding, in preventing excessive deformations and in protecting underground infrastructure during wetting and drying cycles. The effect of the hydraulic properties and geometry of the barrier is investigated by means of an extensive parametric analysis. Finally, recommendations for the design of barrier systems are made

Steady-state and transient dynamic visco-elastic response of concrete and earth dams due to dam-reservoir interaction

The aim of this study is to investigate the effects of dam–reservoir interaction on the dynamic response of dams. Both thin rectangular concrete cantilever and large trapezoidal earth dams are considered with empty and full reservoir. It has recently been shown by Pelecanos et al. [32] that the amplification of accelerations at the crest of the dam depends on the combinations of the frequency of the harmonic acceleration load and the fundamental frequencies of the dam and the reservoir. This study considers transient dynamic loading and selected scenarios of different combinations of the above-mentioned frequencies are examined under random seismic acceleration load. It is shown that for certain cases the amplification of accelerations of the dam can be affected by the presence of the upstream reservoir. In general, thin rectangular concrete cantilever dams are found to be considerably more sensitive to dam–reservoir interaction than large trapezoidal earth dams. Therefore, this investigation examines the significance of dam–reservoir interaction and when this interaction should be taken into consideration or it could be neglected

Use of a Bearing Plate to Enhance the Lateral Capacity of Monopiles in Sand

Offshore foundation systems are constantly evolving to meet the needs of developments in the energy sector. These developments may be induced by the requirements of moving into ever deeper water for hydrocarbon recovery, or creating foundation systems from renewable energy sources such as offshore wind farms. One such approach is that foundation systems are developed which combine several foundation elements to create a ‘hybrid’ system. In this way it may be possible to develop a foundation system which is more efficient for the combination of vertical and lateral loads associated with the offshore environment, and in particular wind powered generators. This paper will present the results from a physical and numerical modelling programme undertaken to investigate the performance of hybrid monopiled-footing foundations under combined monotonic loading conditions in sand

Decomposition mechanism and kinetics of zinc–isophthalate complex with 2,2’-dipyridylamine as a precursor for obtaining nanosized zinc oxide

Studies related to the synthesis of nanosized ZnO as the antibacterial agent have become an interdisciplinary area gathering chemists, physicists, biologists, and medics. The broad scope of materials based on ZnO resulted in the development of various techniques for its preparation. Considering the dependence of particle shape and size onto physical and chemical properties of ZnO, the synthesis procedure is of major importance. In this work, an unconventional methodology of synthesis is proposed for obtaining nanosized ZnO. Polymeric zinc complex containing 2,2’-dipyridylamine (dipya) and dianion of 1,3-benzenedicarboxylic acid (ipht), [Zn(dipya)(ipht)]n, was used as precursor. Besides the crystal structure of [Zn(dipya)(ipht)]n which was already published [1], the luminescent properties are presented in this work. Also, the amazing antibacterial activity of this precursor prompted us to investigate the relationship between the crystal structure and thermal properties, especially if we bear in mind the lack of similar studies in the literature. Therefore, the mechanism and kinetics of its degradation was investigated under non isothermal conditions in nitrogen and air atmospheres. Degradation enthalpies, thermodynamic activation parameters, pre-exponential factor, A, and the apparent activation energy, Ea, were determined for each step using Kissinger’s and Ozawa’s equations. The complexity of degradation steps has been analyzed using isoconversional methods. TG/DCS data were collected at four different heating rates: 10, 15, 20 and 25 ºC min –1 , while the formation of nanosized ZnO was confirmed using XRPD and FESEM techniques. The influence of precursor on the crystallite size and morphology of the resulting ZnO along with its antibacterial activity was examined. The obtained results will be discussed and compared. [1] L. Radovanović, J. Rogan, D. Poleti, M. Milutinović, M.V. Rodić, Polyhedron 112 (2016) 18