Advanced Nonlinear Dynamic Analysis of Arch Dams considering Joints Effects

Influence of joints behavior on arch dams operation during the earthquakes is investigated. The case study is the Karun-1 double curvature arch dam with the height of 200 meters. The arch dam-foundation-reservoir systems are modeled with and without joints and estimate the effects of contraction and lift joints on stresses and displacements response histories for assessing the earthquake performance. According to nolinear dynamical analysis results, inclusion of the contraction and lift joints considerably influenced the dam response

In-situ Lead Removal by Iron Nano Particles Coated with Nickel

This study investigates the potential of nano-zero-valent iron particles coated with nickel in the removal of lead (Pb2+) from porous media. For this purpose, the nano-particles were initially synthesized and later stablilized using the strach biopolymer prior to conducting batch and continuous experiments. The results of the batch experiments revealed that the reaction kinetics fitted well with the pseudo-first-order adsorption model and that the reaction rate ranged from 0.001 to 0.035 g/mg/min depending on solution pH and the molar ratio of Fe/Pb. Continuous experiments showed that lead remediation was mostly influenced not only by seepage velocity but also by the quantity and freshness of nZVI as well as the grain type of the porous media. Maximum Pb2+ removal rates obtained in the batch and lab models were 95% and 80%, respectively. Based on the present study, S-nZVI may be suggested as an efficient agent for in-situ remediation of groundwater contaminated with lead

Modified MODFLOW-based model for simulating the agglomeration and transport of polymer-modified Fe⁰ nanoparticles in saturated porous media

The solute transport model MODFLOW has become a standard tool in risk assessment and remediation design. However, particle transport models that take into account both particle agglomeration and deposition phenomena are far less developed. The main objective of the present study was to evaluate the feasibility of adapting the standard code MODFLOW/MT3D to simulate the agglomeration and transport of three different types of polymer-modified nanoscale zerovalent iron (NZVI) in one-dimensional (1-D) and two-dimensional (2-D) saturated porous media. A first-order decay of the particle population was used to account for the agglomeration of particles. An iterative technique was used to optimize the model parameters. The model provided good matches to 1-D NZVI-breakthrough data sets, with R 2 values ranging from 0.96 to 0.99, and mass recovery differences between the experimental results and simulations ranged from 0.1 to 1.8 %. Similarly, simulations of NZVI transport in the heterogeneous 2-D model demonstrated that the model can be applied to more complicated heterogeneous domains. However, the fits were less good, with the R 2 values in the 2-D modeling cases ranging from 0.75 to 0.95, while the mass recovery differences ranged from 0.7 to 6.5 %. Nevertheless, the predicted NZVI concentration contours during transport were in good agreement with the 2-D experimental observations. The model provides insights into NZVI transport in porous media by mathematically decoupling agglomeration, attachment, and detachment, and it illustrates the importance of each phenomenon in various situations