Tunnelling in urban areas: the use of lateral walls to protect ancient buildings

Famous buildings of historical significance tend to occur in large, old cities such as London, Athens, Rome, Paris and Moscow, which also happen to be cities with some of the oldest and largest metro systems in the world. Metro stations tend to be placed near these monuments in order to attract scores of tourists. Various additional factors, such as traditional construction techniques and shallow foundations, conspire to make ancient buildings much more sensitive to ground subsidence than their modern counterparts. Furthermore, it is essential to make sure ancient buildings remain undamaged, as they are very much in the public eye and any damage sustained will have huge effects on the public opinion of the project. This project investigates the various aspects of constructing lateral walls to protect ancient buildings, the various types of lateral walls, their construction methodology and their design methodology. As background to the lateral wall discussion, this project gives a brief overview of the various tunnelling techniques that exist, the various damage classifications and the considerations specific to boring tunnels near ancient buildings. Finally, this project will focus on the AVE high-speed train line tunnel that is currently being constructed near the foundations of The Sagrada Familia, Barcelona’s iconic cathedral built by the famous Catalan architect, Antoni Gaudí. The scope of this project will primarily concentrate on the piled wall screen that has been built in order to protect the priceless Cathedral. The 2D finite element package Plaxis was used to perform a finite element analysis of the Sagrada Familia, the piled wall and the surrounding area. A comparison was made between five different cases: A piled wall with a concrete block at the head and an area of consolidated soil (the adopted solution); a wall with no concrete block but with consolidated soil; a wall with a concrete block but no consolidated soil; a wall with no concrete block or consolidated soil; and finally, no wall at all. The results show that the wall reduces surface deformations of the Sagrada Familia. The presence of the wall reduces the maximum vertical deformation by 41%. However, the maximum horizontal deformation was unchanged, although its location moved 10m away from the tunnel. With the wall, all points were shifted to the bottom left on the Boscardin and Cording graph, well within the negligible damage range, whereas without it, one point lay within the very slight damage range. However, the concrete block and/or consolidated soil offer little to no reduction in maximum vertical or horizontal deformation. Additionally, their incorporation does not affect the points on the Boscardin and Cording graph. A comparison between the measurements of the FEM analysis and measurements taken in practice conclude that the tunnel, together with the protective measures taken, poses minimal risk to the structural integrity of the Sagrada Familia.Algunos edificios famosos, de importancia histórica, tienden a existir en las ciudades grandes y viejas como Londres, Atenas, Roma, París y Moscú. Estas también resultan ser las ciudades con algunos de los sistemas de metro más grandes y antiguos del mundo. Las estaciones de metro tienden a ser colocadas cerca de los monumentos con el fin de atraer a decenas de turistas. Varios factores adicionales, tales como las técnicas de construcción tradicionales y cimentaciones superficiales, conspiran para hacer que los edificios antiguos sean mucho más sensibles a hundimientos de tierra que sus contrapartes modernas. Además, es esencial para asegurarse de que los antiguos edificios no sufran daños, ya que resultan un hito en las ciudades y cualquier perjuicio causado tendrá efectos enormes en la opinión pública del proyecto. Este proyecto investiga los diferentes aspectos de la construcción de muros laterales para proteger los edificios antiguos, los diversos tipos de paredes laterales, su metodología de construcción y su metodología de diseño. Como base para la discusión de las paredes laterales, este proyecto ofrece una breve descripción de las diferentes técnicas de túneles que existen, las clasificaciones diversas de daños y las peculiaridades de horadar túneles cerca de los edificios antiguos. Por último, este proyecto se centrará en el túnel del AVE línea de alta velocidad que está siendo construido cerca de los cimientos de la Sagrada Familia, la Catedral de Barcelona, construida por el famoso arquitecto catalán Antoni Gaudí. El alcance de este proyecto se centrará principalmente en la pantalla de las paredes apiladas, que ha sido construida con el fin de proteger el precio Catedral. El 2D programa de elementos finitos Plaxis se utilizó para realizar un análisis de elementos finitos de la Sagrada Familia, el muro apilado y sus alrededores. Se hizo una comparación entre los cinco casos diferentes: Una pared con un bloque de hormigón en la cabeza y una área de suelo consolidado (la solución adoptada); un muro sin un bloque de concreto, pero si con el suelo consolidado; una pared con un bloque de hormigón, pero no consolidado el suelo; una pared sin bloques de concreto o suelo consolidado; y, finalmente, ninguna pared. Los resultados muestran que la pared reduce las deformaciones de la superficie de la Sagrada Familia. La presencia de la pared reduce la deformación vertical máxima en un 41%. Sin embargo, la deformación horizontal máxima se mantuvo sin cambios, aunque su ubicación se trasladó 10 metros de distancia del túnel. Con la pared, todos los puntos fueron trasladados a la parte inferior izquierda de la gráfica Boscardin y Cording, bien dentro del rango de daño insignificante, mientras que sin ella, un punto está dentro del rango de daño muy leve. Sin embargo, el bloque de hormigón y/o el suelo consolidado ofrecen poca o ninguna reducción de la deformación máxima vertical u horizontal. Además, su incorporación no afecta a los puntos en la gráfica de Boscardin y Cording. Una comparación entre las mediciones del análisis de elementos finitos y las medidas tomadas en la práctica da la conclusión de que el túnel, junto con las medidas de protección adoptadas, representa un riesgo mínimo para la integridad estructural de la Sagrada Famili

Book Review: Brookfield, S. (2017). Becoming a Critically Reflective Teacher, Second Edition. Jossey-Bass. ISBN 978-1-119-04970-8, hardcover, 286 pages.

A review of Brookfield, S. (2017). Becoming a critically reflective teacher (2nd ed.). Jossey-Bass. ISBN 978-1-119-04970-8, hardcover, 286 pages

Enzyme-induced Formation of ß-Lactoglobulin Fibrils by AspN Endoproteinase

This paper describes a low temperature, enzymatic route to induce fibrillar structures in a protein solution. The route comprises two steps. First, ß-lactoglobulin was hydrolyzed into peptides at pH 8 and 37°C with the enzyme AspN endoproteinase, which resulted in the formation of random aggregates. After hydrolysis, the pH was lowered to 2. As a result, long fibrillar aggregates were formed which was observed using transmission electron microscopy and Thioflavin T fluorescence measurements

Analysis of mixed motion in deterministic ratchets via experiment and particle simulation

Deterministic lateral displacement (DLD) ratchets are microfluidic devices, which are used for size-based sorting of cells or DNA. Based on their size, particles are showing different kinds of motion, leading to their fractionation. In earlier studies, so-called zigzag and displacement motions are observed, and in recent study by our group (Kulrattanarak et al., Meas Sci Technol, 2010a; J Colloid Interface Sci, 2010b), we have shown that also mixed motion occurs, which is an irregular alternation of zigzag and displacement motion. We have shown that the mixed motion is due to asymmetry of the flow lane distribution, induced by the symmetry breaking of the oblique primitive lattice cell (Kulrattanarak et al. 2010b). In this study, we investigate mixed motion in depth by numerical and experimental analysis. Via 3D simulations, we have computed explicit particle trajectories in DLD, and are able to show that there are two critical length scales determining the type of motion. The first length scale d f,1 is the first flow lane width, which determines the transition between zigzag motion and mixed motion. The other length scale, d f,c , determines the transition between mixed motion and displacement motion. Based on our experimental and numerical results we have been able to correlate the migration angle of particles showing mixed motion to the particle size, relative to the two critical length scales d f,1 and d f,