Numerical simulation of seepage maps under dams with sheet piles on their ends

Seepage maps formed by both stream and equipotential lines, emerging under dams with sheet piles on their ends, can be determined by simulating the Laplace conjugate equations using a numerical technique such as the network method. Based on these maps, engineers can immediately deduce the amount of water circulating under the structure and design the sheet piles depth to safe values that allow to limit risks such as siphoning or erosion of the base of the dam. For a fix depth of the upstream sheet pile, seepage maps are shown for different configurations of the downstream sheet pile, in a 2D scenario with finite depth and with large extensions both upstream and downstream of the dam.We would like to thank the Séneca Foundation for the support given to this research, thanks to the scholarship awarded to María Encarnación Martínez Moreno to carry out her doctoral thesis

Verification against failure by piping on retaining structures applying the network method

When designing retaining structures, different phenomena must be studied in order to classify them as safe from a geotechnical point of view. Among them is pipping, a physical process related to seepage under the structure which leads to an unstable situation and might finally cause failure. In order to quantify this risk, a comparison between the critical gradient and the estimated hydraulic gradient is usually accepted. The calculation depends on geometric parameters, geotechnical data and flow boundary conditions, as well as the designed structure. Nevertheless, most of the universal solutions, such as graphics, have not been developed considering an anisotropic medium as foundation soil, so no realistic results are obtained. The aim of this work is to provide a methodology to obtain an estimation of the average gradient using a computational model based on the network method. This consists on the analogy between electrical magnitudes, such as voltage and intensity, and geotechnical variables, which are groundwater head and flow. The safety factor is calculated whether the soil is anisotropic or not, and so, the structure can be classified from a safety point of view.We would like to thank the Séneca Foundation for the support given to this research and for the scholarship awarded to María Encarnación Martínez Moreno to carry out her doctoral thesis

Network model for the numerical solution of groundwater flow. Application to partially penetrating retaining structures in geotechnical engineering

Based on the network simulation method, a precise numerical model is designed for the 2‐D groundwater flow in porous and isotropic aquifers. If a partially penetrating impervious barrier exists, groundwater will flow downstream circumventing the underground structure. The network model is solved free code. Thanks to the powerful mathematical calculation algorithms implemented in is this type of codes, the provided solutions are quite precise for a relatively small grid size, with practically negligible computing times. The proposed model is applied to illustrative problems, providing hydraulic isopotentials and stream lines, showing that as the dam penetration depth increases the hydraulic gradient downstream decreases, thus reducing the risk of hydraulic failure.We would like to thank the Séneca Foundation for the support given to this research and for the scholarships awarded to María Encarnación Martínez Moreno to carry out her doctoral thesis

Calculation of seepage surface and water flow on pumping wells for unconfined aquifers employing the network method

Water scarcity has led to its extraction from underground reserves or aquifers, for which pumping wells are built. For this reason, the phenomenon has been mathematically (and then, computationally) modelled for either confined or unconfined aquifers. As former theoretical approaches to the problem, solution for groundwater flow in unconfined aquifers did not consider vertical flow and variables such as seepage surface were not studied. The aim of this work is to provide a methodology to estimate both parameters using a computational model based on the network method. This methodology consists on the analogy between electrical quantities (voltage and intensity) and geotechnical variables (water potential and flow). The results obtained with this tool are compared to those from scale models.We would like to thank the SéNeCa Foundation for the support given to this research and for the scholarship awarded to María Encarnación Martínez Moreno to carry out her doctoral thesis

The dimensional character of permeability. Dimensionless groups that govern Darcy’s flow in anisotropic porous media.

The dimensional character of permeability in anisotropic porous media, that is,its dimension or dimensional equation, is an information that allows setting thedimensionless groups that govern the solution of the flow equation in terms ofhydraulic potential patterns. However, employing the dimensional basis {L, M,T} (length, mass, time), the dimensionless groups containing the anisotropic per-meability do not behave as independent monomials that rule the solutions. Inthis work, the contributions appearing in the literature on the dimensional char-acter of permeability are discussed and a new approach based on discriminatedand general dimensional analysis is presented. This approach leads to the emer-gence of a new and accurate dimensionless group,kxkyl∗2yl∗2x, a ratio of permeabilitiescorrected by the squared value of an aspect factor, beingl∗xandl∗ytwo arbitrarylengths of the domain in the directions that are indicated in their subscripts. Spe-cific values of this lengths, which we name ‘hidden characteristic lengths’, arealso discussed in this article. To check the validity of this dimensionless group,numericalsimulationsoftwoillustrative2-Dseepagescenarioshavebeensolved.The authors would like to thank SéNeCa Foundation for the support given to this research and for the scholarships awarded to Martínez-Moreno E. to carry out her doctoral thesis

The Menger number of the strong product of graphs

The xy-Menger number with respect to a given integer ℓ, for every two vertices x, y in a connected graph G, denoted by ζℓ(x, y), is the maximum number of internally disjoint xy-paths whose lengths are at most ℓ in G. The Menger number of G with respect to ℓ is defined as ζℓ(G) = min{ζℓ(x, y) : x, y ∈ V(G)}. In this paper we focus on the Menger number of the strong product G1 G2 of two connected graphs G1 and G2 with at least three vertices. We show that ζℓ(G1 G2) ≥ ζℓ(G1)ζℓ(G2) and furthermore, that ζℓ+2(G1 G2) ≥ ζℓ(G1)ζℓ(G2) + ζℓ(G1) + ζℓ(G2) if both G1 and G2 have girth at least 5. These bounds are best possible, and in particular, we prove that the last inequality is reached when G1 and G2 are maximally connected graphs.Ministerio de Educación y Ciencia MTM2011-28800-C02-02Generalitat de Cataluña 1298 SGR200

Resolution of Geotechnical Engineering problems with Plaxis 2D

The book consists of seven exercises, each of them easy to identify and relate to the different thematic units that students study throughout their training in soil engineering: safety factors in cuttings and embankments, soil consolidation, seepage flow under retaining structures, shallow foundations, diaphragm walls, and deep foundations. The book is designed to gradually learn the use of the software PLAXIS 2D, so a user with no previous experience with the software should follow the order in which the exercises appear in the text. This book and its contents are only for educational purposes. Its elaboration has been authorized by the PLAXIS brand, owned by the company Bentley Systems

On average connectivity of the strong product of graphs

The average connectivity κ(G) of a graph G is the average, over all pairs of vertices, of the maximum number of internally disjoint paths connecting these vertices. The connectivity κ(G) can be seen as the minimum, over all pairs of vertices, of the maximum number of internally disjoint paths connecting these vertices. The connectivity and the average connectivity are upper bounded by the minimum degree δ(G) and the average degree d(G) of G, respectively. In this paper the average connectivity of the strong product G1 G2 of two connected graphs G1 and G2 is studied. A sharp lower bound for this parameter is obtained. As a consequence, we prove that κ(G1 G2) = d(G1 G2) if κ(Gi) = d(Gi), i = 1, 2. Also we deduce that κ(G1 G2) = δ(G1 G2) if κ(Gi) = δ(Gi), i = 1, 2.Ministerio de Educación y Ciencia MTM2011-28800-C02-02Generalitat de Cataluña 1298 SGR200

A new microbial gluten-degrading prolyl endopeptidase: Potential application in celiac disease to reduce gluten immunogenic peptides

Gluten is a complex of proteins present in barley, wheat, rye and several varieties of oats that triggers celiac disease in genetically predisposed subjects. Gluten is notoriously difficult to digest by mammalian proteolytic enzymes and therefore, proline-rich digestion-resistant peptides contain multiple immunogenic epitopes. Prolyl endopeptidases (PEP) hydrolyse internal proline residues on the carboxyl side of peptides and have been proposed for food gluten detoxification and as oral enzyme supplementation for celiacs. The aim of this study was to identify new gluten-degrading microbial enzymes with the potential to reduce gluten immunogenicity by neutralizing its antigenic epitopes. Using a gluten-degrading colony screening approach, a bacterial isolate (2RA3) displaying the highest glutenase activity was selected, characterized and its genome completely sequenced. The identification through 16S rDNA gene sequencing showed a 99,1% similarity to Chryseobacterium taeanense. Hydrolysis of gluten immunogenic peptides (GIP) was further monitored, over a 48-hour period, by colony encapsulation in gliadin-containing microspheres, followed by detection with the G12 anti-GIP monoclonal antibody. Glutenase activity was detected in the extracellular medium of 2RA3 cultures, where gel electrophoresis and gliadin zymography revealed the presence of a ~50 kDa gluten-degrading enzyme. Nano-ESI-Q-TOF of the excised active band identified 7 peptides contained in the protein product predicted for an open reading frame (ORF) in the 2RA3 genome. Based on sequence similarity to the PEP family, the new enzyme was named PEP 2RA3. The PEP 2RA3 coding sequence was PCR-amplified from C. taeanense 2RA3, cloned and expressed in Escherichia coli as a C-terminally His-tagged recombinant protein and purified by Ni-NTA affinity chromatography. The recombinant protein, with predicted molecular mass and isoelectric point of 78.95 kDa and 6.8, respectively, shows PEP activity with standard chromogenic substrates, works optimally at pH 8.0 and 30°C and remains stable at pH 6.0 and 50°C, indicating a potential use in gluten-containing food process applications. The ability of the recombinant enzyme to degrade GIP in beer into smaller peptides was confirmed.Ministry of Science and Innovation AGL2009-0906

Resolución de problemas de ingeniería geotécnica mediante plaxis 2D

El libro consta de siete ejercicios, cada uno de ellos fácil de identificar y relacionar con las diferentes unidades temáticas que los alumnos estudian a lo largo de su formación en ingeniería del terreno: factores de seguridad en desmontes y terraplenes, consolidación de suelos, redes de flujo bajo estructuras de retención, cimentaciones superficiales, muros pantalla y cimentaciones profundas. El libro está concebido para aprender el manejo del programa PLAXIS 2D de manera gradual, con lo cual un usuario sin experiencia previa con el programa debería seguir el orden en el que aparecen los ejercicios en el texto. Este libro y su contenido tienen únicamente un fin educativo. La elaboración de este ha sido autorizada por la marca PLAXIS, propiedad de la compañía Bentley Systems.La elaboración de este ha sido autorizada por la marca PLAXIS, propiedad de la compañía Bentley Systems